JPH08264530A - Semiconductor device manufacturing method and semiconductor device manufacturing apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for manufacturing a semiconductor device and a dry etching apparatus in which a tungsten film is formed on an insulating layer via an adhesion layer, and then the tungsten film and the adhesion layer are etched, without reducing throughput. Forming the adhesion layer and the main conductive film, ensuring the stability and reproducibility of the process, reducing the installation area of the device as much as possible, the substrate surface after low temperature etching without reducing the processing capacity of the device In order to prevent dew condensation, the resist film is removed without leaving reaction products. A gas containing tungsten is reduced mainly by diborane to form a first tungsten film 14 on the insulating layer 11.
And a step of forming a second tungsten film 15 on the first tungsten film 14 by reducing a gas containing tungsten with hydrogen or silane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device and a device for manufacturing a semiconductor device, and more specifically, a tungsten film is formed on an insulating layer via an adhesion layer, and then the tungsten film and the adhesion layer are formed. The present invention relates to a method for manufacturing a semiconductor device to be etched and a dry etching device.

In recent years, as semiconductor devices have become finer and more highly integrated, the aspect ratio of contact holes and via holes has tended to become even higher. Therefore, there is a need for a technique for filling contact holes and the like with blanket tungsten to improve the coverage of the upper wiring layer and to obtain good contact with the upper and lower wiring layers. Further, with the progress of miniaturization and high integration of semiconductor devices, it is becoming difficult to maintain and improve the reliability of the metal wiring layer. In particular, when an aluminum or aluminum alloy single layer is used as a submicron level metal wiring layer, it is becoming difficult to apply it to products requiring high reliability in terms of stress migration and electromigration. As a countermeasure against this, a laminated wiring structure of an aluminum film and another metal film, for example, a multilayer wiring layer such as an Al film / TiN film is used. However, in order to obtain higher reliability, tungsten is being used as a new wiring material.

When a tungsten film is used, a conductive film such as a titanium nitride film called an adhesion layer is often interposed in order to improve the adhesion between the underlying insulating layer and the tungsten film. At present, a method for etching these films suitable for mass production has not been established, and various studies have been made. Further, the development of an etching apparatus used in this etching method is also in progress.

[0004]

2. Description of the Related Art Generally, the blanket tungsten 2 has poor adhesion to the oxide film 1 and may be peeled off as shown in FIG. 9 (a). Therefore, as shown in FIG. 9B, the adhesion layer 3 is interposed between the tungsten film 2 and the oxide film 1 to enhance the adhesion and prevent the tungsten film 2 from peeling off.

A TiN film is often used as the adhesion layer 3 and is formed by a sputtering method, but since it is different from the CVD method for forming an interlayer insulating film or a tungsten film, an apparatus is used between two film forming steps. As it goes in and out, the throughput is lowered. Moreover, in recent years, T
Although the technique for forming the iN film is being established, continuous deposition in the same chamber is difficult because the process conditions such as the reaction gas are significantly different from the blanket tungsten deposition method. Not suitable for.

By the way, as shown in FIG. 10A, the tungsten film 2a formed by the reduction of diborane (B ₂ H ₆ ) does not require an adhesion layer and is directly formed on the insulating film such as the silicon oxide film 1a. Since it can be formed, it is suitable for improving throughput. Further, since it is the same CVD method as blanket tungsten, it has a feature that process development can be easily performed. Therefore, as shown in FIGS. 10A and 10B, it has been tried to use the tungsten film 2a formed by using diborane on the insulating film 1a as a wiring layer. Note that FIG.
(B) shows the wiring layer 2b connected to the semiconductor substrate 5 at the bottom through the contact hole 6 formed in the insulating film 1b on the semiconductor substrate 5.

Further, since the wiring layer is formed from the formed alloy film containing titanium and tungsten film, a step of etching these is required. A gas containing fluorine is often used for etching the tungsten film, and it is known that the substrate temperature at the time of etching is an important parameter for controlling the processed shape. According to known examples, for example, the substrate temperature is a low temperature of −20 ° C. or lower (practically,
-35 to -50 ° C is preferable. ) Is required. On the other hand, under these conditions, the etching of the alloy containing titanium is difficult to proceed, and it is difficult to increase the etching selection ratio between the base insulating film (silicon oxide film) and the tungsten film. When the alloy film and the alloy film are etched in the same chamber, the condition has a very narrow margin.

In order to avoid this problem, it is necessary to etch each film under different process conditions.
Therefore, conventionally, a method has been adopted in which the tungsten film and the alloy film containing titanium are etched by different devices.

[0009]

However, when a tungsten film is formed by using diborane, if the film is thickened to reduce the resistance, as shown in FIG. 10A, the surface of the tungsten film 2a becomes uneven. 4 (deterioration of surface morphology), as shown in FIG. 10B, the invasion into the underlying semiconductor substrate 5 becomes remarkable, and the semiconductor substrate 5
When a shallow PN junction is formed, the penetration layer 7 penetrates the PN junction and causes an electrical short circuit.

Further, when the tungsten film and the TiN film are etched, the process margin is narrow, as described above, so that stability and reproducibility during mass production of the product are ensured.
Etching in the same chamber is difficult and there is a problem that throughput cannot be improved. If the two devices are separately etched to increase the process margin, there is a problem in that the device cost and the installation area increase.

In addition to the above, there are the following problems that must be solved. In the case of low temperature etching, if the wafer after etching is exposed to the atmosphere as it is, the water in the atmosphere is condensed on the surface of the wafer because it is cold, and it reacts with the reaction products remaining on the wafer. There is a problem that foreign matter is generated or a melted reaction product is generated and acts on the wiring layer to cause a defect in the formed wiring layer. To avoid this, a heater etc. is required to evaporate the water,
This not only increases the equipment cost but also requires heating time, resulting in a decrease in wafer processing capacity.

When etching is performed at a low temperature using the resist film as a mask, reaction products that are difficult to remove adhere to the sidewalls of the resist film after etching, and it is often impossible to remove them by ashing using oxygen plasma. If there is such a residue, abnormal growth or the like will occur when an insulating film is deposited on it, leading to a decrease in the yield of non-defective products. Further, adding a process for removing this reaction product causes an increase in equipment cost and a decrease in wafer processing capacity.

The present invention was created in view of the problems of the above-mentioned conventional example, and it is possible to form a wiring layer composed of an adhesion layer and a main conductive film without lowering throughput, and to improve process stability and process stability. Ensuring reproducibility, reducing the installation area of the device as much as possible, preventing dew condensation on the substrate surface after low temperature etching without lowering the processing capacity of the device, resist film without leaving reaction products It is an object of the present invention to provide a method for manufacturing a semiconductor device and a device for manufacturing a semiconductor device capable of removing the above.

[0014]

To solve the above problems, firstly, a step of reducing a gas containing tungsten mainly by diborane to form a first tungsten film on an insulating layer, and a gas containing tungsten containing hydrogen or hydrogen are used. And a step of forming a second tungsten film on the first tungsten film by reducing with silane, and secondly, an insulating layer is formed on the semiconductor substrate. After the formation, a step of forming an opening in the insulating layer, a step of reducing a gas containing tungsten mainly with diborane to cover the opening to form a first tungsten film on the insulating layer, and a step of forming tungsten Reducing the containing gas with hydrogen or silane to form a second tungsten film on the first tungsten film. Thirdly, the first tungsten film is an adhesion layer that strengthens the adhesion between the insulating layer and the second tungsten film, and the second tungsten film is achieved. Is a main conductive layer, and is achieved by the method for manufacturing a semiconductor device according to the first or second invention. Fourth, the first tungsten film and the second tungsten film are blanket tungsten. First characterized in that
A fifth aspect of the present invention is achieved by the method for manufacturing a semiconductor device according to any one of the third to fifth aspects, and fifthly, after forming the second tungsten film, etching the first tungsten film and the second tungsten film. It is achieved by the method for manufacturing a semiconductor device according to the fourth aspect of the present invention, which is characterized in that the first tungsten film and the second tungsten film are formed after the formation of the second tungsten film. This is achieved by the method for manufacturing a semiconductor device according to the fourth invention, characterized in that the film is selectively etched to form a wiring layer. Seventh, a titanium nitride film and a tungsten film are sequentially formed on a substrate. A step of forming, a step of holding the substrate at a temperature of −20 ° C. or lower in a reduced pressure atmosphere to etch the tungsten film with a gas containing fluorine, and the tungsten. After the etching of the silicon film, the substrate is moved to the etching place of the titanium nitride film without being exposed to the atmosphere, and the substrate is kept at a temperature of 15 ° C. or higher in a reduced pressure atmosphere by chlorine or a gas containing chlorine. And a step of etching the titanium nitride film.
The gas containing fluorine is nitrogen trifluoride, which is achieved by the method for manufacturing a semiconductor device according to the seventh invention. Ninthly, the tungsten film and the titanium nitride film are used with a resist film as a mask. After etching
A method of manufacturing a semiconductor device according to a seventh or eighth aspect of the present invention, wherein the resist film is removed by exposing the resist film to a mixed gas of an activated gas containing fluorine and a gas containing oxygen. And a means for cooling the substrate, the first gas on the substrate being depressurized by the activated first gas.
A first chamber for etching the object to be etched,
A second chamber for heating the substrate, cooling the substrate, and etching the second object to be etched on the substrate in a reduced pressure by the activated second gas;
And the second chamber, and a transfer path that holds the depressurized state and can move the substrate between the chamber and the second chamber.

[0015]

In the film forming method according to the present invention, the gas containing tungsten is reduced mainly by diborane to form the first tungsten film, and the gas containing tungsten is reduced by hydrogen or silane to form the second tungsten film. Of tungsten film is formed. Therefore, the first and second tungsten films can be continuously formed only by switching the reaction gas. By this, both by the CVD method,
Film formation can be performed in the same chamber, and throughput can be improved.

In the wiring layer having the first tungsten film formed by the reduction of diborane as the adhesion layer and the second tungsten film formed thereon by the reduction of hydrogen or silane as the main conductive layer, the insulating layer is formed. Improves adhesion with layers,
In addition, it is possible to increase the film thickness without deteriorating the surface morphology. Furthermore, when the above-mentioned two-layer tungsten film is embedded in the opening formed in the insulating layer on the semiconductor substrate, the second tungsten film as the main conductive layer is formed on the first tungsten film as the adhesion layer. Therefore, the first tungsten film formed by the reduction of diborane and in contact with the semiconductor substrate at the bottom of the opening may be thinned, so that the entry of tungsten into the semiconductor substrate can be suppressed.

Further, according to the etching method of the present invention, the tungsten film is etched at a low temperature of −20 ° C. or lower, and the TiN film is etched at a temperature of 15 ° C. or higher. Therefore, when etching the tungsten film, TiN
The selectivity with respect to the film can be ensured, and the etching rate of the TiN film and the selectivity with the underlying insulating layer can be sufficiently ensured when the TiN film is etched. This ensures process stability and reproducibility.

Further, in the method of removing a resist film according to the present invention, the resist film used as the etching mask is removed by dry ashing using a gas containing oxygen gas and fluorine. By the way, since the reaction product generated by etching contains tungsten and TiN, it is very difficult to remove them by dry ashing using only oxygen gas. By adding them, they can be effectively removed.

According to the etching apparatus of the present invention, the first and second films capable of etching different films respectively.
By connecting the chambers of with a transport path that can reduce pressure,
The substrate can be moved from the first chamber to the second chamber without exposure to the atmosphere. For this reason, dew condensation due to moisture in the atmosphere does not occur on the surface of the substrate transferred to the second chamber.

Further, since the temperature of the substrate transferred from the first chamber capable of etching at a low temperature to the second chamber capable of etching at a higher temperature is increased, the temperature of the substrate for heating the substrate is increased. Since no special equipment or processing is required, equipment cost can be reduced and throughput can be improved. Further, by using the etching apparatus in which the two chambers are connected, it is possible to suppress an increase in the apparatus cost and to reduce the installation area of the apparatus as compared with the case where two separate etching apparatuses are used. You can

[0021]

【Example】

 (1) Adhesion layer and main conductive layer according to Example 1 of the present invention
Description of Film Forming Method of Adhesive Layer and Main Conductor according to First Embodiment of the Present Invention
It is a side view of the CVD apparatus used for the method of forming a layer.
Hold wafer 97 in chamber 91, as shown in FIG.
The substrate holder 92 having the heater 93 built therein is installed.
Have been. In addition, tungsten hexafluoride (WF ₆)gas
The first gas inlet 94 through which the gas is introduced into the chamber 91
And diborane (B ₂H₆) And hydrogen (H₂) Or silane
(SiH_Four) Mixed gas is introduced into the chamber 91.
The second gas inlet 95 and the unnecessary reaction gas are discharged, or
Or an exhaust pump is connected to reduce the pressure inside the chamber 91.
The exhaust port 96 is formed. The heater is
It may be provided outside the chamber.

FIGS. 1A to 1E are sectional views showing a method of forming a buried layer (plug) of a contact hole according to the first embodiment of the present invention using the CVD apparatus of FIG. . A tungsten film formed by reducing WF ₆ gas mainly with diborane serves as an adhesion layer 14, and a tungsten film formed by reducing WF ₆ gas with hydrogen serves as a main conductive layer 15. Both tungsten films are formed as blanket tungsten having no growth selectivity.

First, as shown in FIG. 1A, an insulating layer 12 made of a silicon oxide film is formed on a silicon substrate (semiconductor substrate) 11, and then a contact hole 13 is formed in the insulating layer 12. At this time, the silicon substrate 11 is exposed at the bottom of the contact hole 13. Then, FIG.
As shown in (b), a WF ₆ gas with a flow rate of 100 cc / min, a B ₂ H ₆ gas with a flow rate of 100 cc / min, and a flow rate of 1000 c
A mixed gas of H ₂ gas of c / min is supplied into the chamber 91, and a film thickness of 100 to 1000 is formed on the insulating layer 12 by the CVD method under the conditions of a gas pressure of 100 Torr and a substrate temperature of 450 ° C.
A Å first tungsten film (W film) 14 is formed. In this case, the WF ₆ gas is reduced mainly by the B ₂ H ₆ gas to form the adhesion layer 14 made of the first tungsten film.

Then, as shown in FIG. 1C, B ₂ H
The supply of ₆ gas is stopped, a mixed gas of WF ₆ gas having a flow rate of 100 cc / min and H ₂ gas having a flow rate of 1000 cc / min is supplied into the chamber 91, and the gas pressure is 100 Torr and the substrate temperature is 450 ° C. A main conductive layer 15 made of a second tungsten film having a film thickness of 100 to 1000 Å is formed on the adhesion layer 14 by the CVD method. In this case, the WF ₆ gas is reduced by the H ₂ gas to form the second tungsten film. As a result, the first and second tungsten films 14 and 15 are buried in the contact hole 13 and further stacked on the insulating layer 12. At this time, the surface of the silicon substrate 11 becomes substantially flat.

Then, as shown in FIG. 1 (d), NF ₃
The first and second tungsten films 14 on the insulating layer 12 are etched back by dry etching using gas,
15 is removed, and the first and second tungsten films 14a and 15a are left only in the contact hole 13. As a result, the plug 16 is formed. SF ₆ may be used as the etching gas. Alternatively, wet etching using a mixed solution of HF + HNO _{3 or} a mixed solution of H ₂ O ₂ + NH ₃ may be performed.

Next, as shown in FIG. 1E, the contact hole 13 is covered to cover the insulating layer 12 with aluminum /
After forming the copper alloy film, patterning is performed to form a wiring layer 17 connected to the plug 16. As a result, the silicon substrate 11 and the wiring layer 17 are connected via the plug 16. After that, as shown in FIG. 2B, if necessary, an interlayer insulating film 18 covering the wiring layer 17 is formed,
Further, another wiring layer 2 in which a plug 22 is embedded in the via hole 19 formed in the interlayer insulating film 18 through the same steps as described above and further connected to the wiring layer 17 via the plug 22
3 may be formed.

As described above, according to the film forming method of the first embodiment of the present invention, after the adhesion layer 14 is formed, diborane in the reaction gas introduced into the chamber 91 is simply stopped. Since a desired reaction gas for forming the conductive layer 15 can be supplied into the chamber 91, the adhesion layer 1
4 and the main conductive layer 15 can be continuously formed.
As a result, the same chamber 91 is formed by the CVD method.
It is possible to form a film in the inside, and the throughput can be improved.

Further, when the above-mentioned two layers of tungsten film are buried in the contact hole 13 formed in the insulating layer 12 on the silicon substrate 11, the second tungsten film as the main conductive layer 15 is formed, so that diborane is not formed. Since the first tungsten film 14, which is formed by reduction and is in contact with the silicon substrate 11 at the bottom of the contact hole 13, as the adhesion layer 14, may be thinned, it is possible to suppress the penetration of tungsten into the silicon substrate 11. is there.

Although the tungsten films of the adhesion layer 14 and the main conductive layer 15 are formed as blanket tungsten in the above embodiment, they may be formed by selective growth. Although the present invention is applied to the case where the plug 16 is formed, as shown in FIG. 2A, the wiring layer 24 including the first and second tungsten films 14 and 15 is formed on the insulating layer 12. The present invention can also be applied to the case of forming. In this case, the first tungsten film formed by reduction of diborane is used as the adhesion layer 14, and the second tungsten film formed thereon by reduction of hydrogen is used as the main conductive layer 15, so that these tungsten films are formed. The wiring layer formed by the method can improve the adhesion with the insulating layer 12 and can be thickened without deteriorating the surface morphology.

Further, although a silicon oxide film is used as the underlying insulating layer 12, phosphorus glass (PSG film), phosphorus boron glass (BPSG film), silicon oxynitride film (SiO 2).
It may be an N film) or a silicon nitride film (SiN film). Although the substrate temperature is 450 ° C, it is 300 ° C.
It may be more than a certain degree. Furthermore, although a mixed gas of B ₂ H ₆ + WF ₆ + H ₂ is used as a reaction gas for forming the adhesion layer 14, a mixed gas of B ₂ H ₆ + WF ₆ + SiH ₄ may be used. Although a mixed gas of WF ₆ + H ₂ is used as a reaction gas for forming the main conductive layer 15, a mixed gas of WF ₆ + SiH ₄ may be used.
In this case, the substrate temperature is suitably 350 ° C. (2) Description of Etching Device According to Second Embodiment of the Present Invention FIGS. 4A, 5 and 6 are side views showing an etching device according to a second embodiment of the present invention.

FIG. 4A shows the overall structure of an etching apparatus in which a first chamber and a second chamber capable of etching different kinds of conductive films are connected in series. In FIG. 4A, reference numeral 101 denotes a cooling means for the wafer 100 on which an object to be etched is formed, and a main conductive layer (first object to be etched) formed of a tungsten film under reduced pressure by activated gas. A first chamber 102 for etching is provided with a heating means and a cooling means for the wafer 100, and an adhesion layer (second etching object) made of a tungsten film under a reduced pressure by an activated gas.
The second chamber 103 for etching the wafer is connected to the first chamber 101 and the second chamber 102, and is a transfer chamber (transfer path) capable of holding the depressurized state and moving the wafer 100 between them. .

Between the first chamber 101 and the transfer chamber 103 and between the second chamber 102 and the transfer chamber 103, valves (not shown) for opening and closing the passage of the wafer 100 are provided. Reference numeral 104 is an inlet side load lock chamber connected to the first chamber 101. Valves for opening and closing the passage of the wafer 100 are provided at the connecting portion between the first chamber 101 and the inlet side load lock chamber 104 and the inlet of the wafer 100 on the opposite side of the connecting portion. Inlet side load lock chamber 1 at atmospheric pressure
After the wafer 100 is loaded into the chamber 04 from the outside, the inside of the inlet side load lock chamber 104 is depressurized so as to match the already depressurized room pressure of the first chamber 101.
After that, the wafer 100 is loaded into the first chamber 101.

Reference numeral 105 is an outlet-side load lock chamber connected to the second chamber 102. Second chamber 1
01 and the connection part of the outlet side load lock chamber 105,
Valves for opening and closing the passage of the wafer 100 are provided at the connection portion and the outlet of the wafer 100 on the opposite side. Before the wafer 100 is unloaded from the second chamber 102 to the exit side load lock chamber 105, the inside of the exit side load lock chamber 105 is decompressed to match the already decompressed pressure inside the second chamber 102. Then, after the wafer is loaded, the inside of the exit side load lock chamber 105 is returned to the atmospheric pressure, and then the exit side load lock chamber 1
The wafer 100 is unloaded from 05.

Each of the above chambers is connected to an exhaust pump (exhaust device) for reducing the pressure in each chamber, and exhaust ports 106 to 110 are connected to each chamber.
Have. Instead of the etching apparatus having the configuration shown in FIG. 4A, an etching apparatus having the configuration shown in FIG. 4B may be used. FIG. 4B is a plan view showing the overall configuration of the etching apparatus.

In FIG. 4 (b), the difference from FIG. 4 (a) is that the first part is centered on the transfer chamber (transfer path) 103a.
The second chambers 101a and 102a and the inlet-side and outlet-side load-lock chambers 104a and 105a are connected to the transfer chamber 103a. Therefore, when the silicon substrate 100 is taken in and out of the first chamber 101a and the second chamber 102a, both of the silicon substrate 1 and
00 passes through the same transfer chamber 103a. Each room 101a / 103a, 102a / 103a, 104a /
A valve (not shown) that opens and closes the passage of the silicon substrate 100 is provided at the connection portion between 103a and 105a / 103a. Further, valves for opening and closing the passage of the wafer 100 are provided at the inlet of the inlet side load lock chamber 104a and the outlet of the outlet side load lock chamber 105a.

FIG. 5 is a side view showing the detailed structure of the first etching chamber partitioned from the outside by the first chamber 101. In FIG. 5, reference numeral 111 denotes a substrate holder for holding the wafer 100, which is installed in the first chamber 101, and is a flow path (cooling means) through which a temperature-controlled refrigerant, for example, water containing an antifreeze solution is passed. 112 is formed. The substrate holder 111 also serves as a first electrode for applying high frequency power for converting the etching gas into plasma. Reference numeral 113 is a second electrode that applies high-frequency power for converting the etching gas into plasma, and is arranged so as to face the substrate holder 111 that is the first electrode. A high frequency power supply 114 for supplying high frequency power is connected to the second electrode 113. Also, the first electrode 1
11 is grounded.

Reference numeral 115 is a gas inlet for introducing an etching gas into the first chamber 101. FIG. 6 is a side view showing the detailed configuration of the second etching chamber that is partitioned from the outside by the second chamber 102. Figure 6
The second etching chamber has a structure similar to that of the first etching chamber. The difference from the first etching chamber is that the substrate holder 1 is installed in the second chamber 102.
In order to keep the temperature of the mounted substrate at 15 ° C. or higher, the temperature control means 1 has a heater (heating means) 122 for heating the substrate and a cooling means 123 for cooling it.
24 is built in.

The substrate holder 121 also serves as the first electrode and applies high-frequency power between the substrate holder 121 and the second electrode 125.
The reaction gas between the electrodes 121 and 125 is turned into plasma. A high frequency power source 126 is connected to the second electrode 125, and the first electrode 121 is grounded. Further, the second chamber 102 has a gas inlet 127 and an exhaust port 109.
Is connected.

In the above etching apparatus, the first and second chambers 10 capable of etching different films, respectively.
The first chamber 101 and the second chamber 102 are connected to each other by connecting the first and second chambers 1 and 102 with each other by the transport path 103 capable of reducing the pressure.
Moreover, the wafer 100 can be moved without being exposed to the atmosphere. For this reason, dew condensation due to moisture in the atmosphere does not occur on the surface of the wafer 100 transferred to the second chamber 102.

Further, the wafer 100 transferred from the first chamber 101, which is etched at a low temperature, to the second chamber 102, which is etched at a higher temperature than that.
Since the temperature rises, the need for special equipment or processing for heating the wafer 100 is eliminated, and the equipment cost can be reduced and the throughput can be improved. Next, a plasma asher for removing the resist film will be described with reference to FIG. FIG. 7 is a side view showing the configuration of the downflow asher.

As shown in FIG. 7, the chamber 131 is divided into an etching chamber 132, a plasma generation chamber 133, and a microwave introduction chamber 134. The etching chamber 132 and the plasma generation chamber 133 are partitioned by a partition plate having holes through which plasma passes, and the plasma generation chamber 133 and the microwave introduction chamber 134 are partitioned by a partition plate 136 such as quartz through which microwaves are transmitted. It is partitioned.

A gas inlet 138 for introducing a reaction gas into the plasma generating chamber 133 is provided in the plasma generating chamber 133.
Are formed. The etching chamber 132 has an exhaust port 139 connected to an exhaust pump (not shown) for exhausting unnecessary reaction gas or reducing the pressure in the etching chamber 132 and the plasma generation chamber 133. Further, in the etching chamber 132, a substrate holder 137 on which the wafer 100 to be processed is placed is installed. (3) Description of Etching Method for Adhesion Layer and Main Conductive Layer According to Third Embodiment of Present Invention FIGS. 8A to 8D are cross-sectional views showing an etching method according to a third embodiment of the present invention. It is a figure. Description will be made using the etching apparatus of FIGS. 4 to 6 and the downflow plasma asher of FIG. 7. In the following description, each chamber 101a / 103a, 102a / 103a, 104a
/ 103a, 105a / 103a, the opening and closing of the valves provided at the inlet of the inlet side load lock chamber 104 and the outlet of the outlet side load lock chamber 105 are omitted, but they are appropriately performed. I shall.

As shown in FIG. 8A, the wafer 100 to be processed has an insulating layer 32 made of a silicon oxide film formed on a silicon substrate 31 having a diameter of 6 inches.
Covering the contact hole 33 formed in the insulating layer 3
2 and a TiN film (adhesion layer) 34 with a film thickness of 50 nm and a film thickness 3
A tungsten film (main conductive layer) 35 having a thickness of 50 nm is formed. Further, a resist mask 36 having a film thickness of 1700 nm is formed on the tungsten film 35 in order to form a wiring layer having a predetermined shape at a desired position.

First, the inlet side load lock chamber 104
After the wafer 100 is loaded into the wafer, the inlet-side load lock chamber 104, the first chamber 101, the transfer chamber 103, and the second chamber 102 are evacuated and decompressed. When the predetermined pressure is reached, the wafer 1 is placed in the first chamber 101.
00 is loaded and placed on the substrate holder 111.

Subsequently, the wafer 10 is cooled by the cooling means 112.
0 is cooled and the substrate temperature is kept at -50 ° C. Then
A nitrogen trifluoride (NF ₃ ) gas having a flow rate of 150 cc / min is introduced from the gas introduction port 115 to maintain the gas pressure in the first chamber 101 at 100 mTorr.

Next, the first electrode 111 and the second electrode 1
A high frequency power of 200 W is applied between 13. This allows
The NF ₃ gas between the electrodes 111 and 113 is turned into plasma, the tungsten film 35 is exposed to this, and etching is started. At this time, the etching rate of the tungsten film 35 is 300 nm / min, and the etching selection ratio of the tungsten film 35 to the TiN film 34 is 100 or more.

After a predetermined time has elapsed, the tungsten film 35 is etched as shown in FIG. 8 (b). Next, after the wafer 100 is unloaded into the transfer chamber 103, it is further loaded into the second chamber 102 to load the substrate holder 121.
Place on top. At this time, since the wafer 100 is not exposed to the atmosphere until it is loaded into the second chamber 102,
Condensation on the surface can be suppressed.

Next, the wafer 100 on the substrate holder 121.
Is heated and maintained at a temperature of 25 ° C. Then, chlorine (Cl ₂ ) gas having a flow rate of 100 cc / min is introduced from the gas introduction port 127, and the gas pressure in the second chamber 102 is set to 50 mT.
Hold at orr. Next, high frequency power 400 W is applied between the first electrode 121 and the second electrode 125. As a result, Cl ₂ gas between the electrodes 121 and 125 is turned into plasma, the TiN film 34 is exposed to this, and etching is started. At this time, the etching rate of the TiN film 34 is 20.
0 nm / min, and the TiN film 3 with respect to the tungsten film
The etching selection ratio of No. 4 is 100 or more, and the etching selection ratio of the TiN film 34 to the silicon oxide film is 7 or more. Therefore, even if the resist mask 36 is etched, the tungsten film 35a that covers the TiN film 34 serves as a mask, so that the etching shape is not abnormal.

After the lapse of a predetermined time, the TiN film 34 is etched as shown in FIG. 8 (c). This completes the etching of the tungsten film 35 and the TiN film 34. Next, the exit side load lock chamber 105
After depressurizing, the wafer 100 is unloaded from the second chamber 102 to the exit side load lock chamber 105. Then, after returning the exit side load lock chamber 105 to atmospheric pressure, the wafer 100 is taken out.

Next, the wafer 100 is loaded into the chamber 131 of the plasma asher and placed on the substrate holder 133. Next, the wafer 100 on the substrate holder 133 is heated and kept at a temperature of 30 ° C. Then, the gas inlet 138
From which a mixed gas of carbon tetrafluoride (CF ₄ ) gas and a flow rate of 900 cc / min of oxygen (O ₂ ) gas was introduced, and the gas pressure in the chamber 131 was set to 900 mTorr.
Hold at r.

Next, 900 W of electric power is applied to the microwave introduction chamber 1
Lead to 34. As a result, C in the plasma generation chamber 133
The F ₄ + O ₂ gas absorbs microwave power and is turned into plasma, and the resist mask 36 is exposed to this, and etching starts. At this time, since the reaction product generated by etching contains tungsten and TiN,
Although it is very difficult to remove them by dry ashing using only O ₂ gas, they can be effectively removed by adding CF ₄ gas.

After a predetermined time has elapsed, the resist mask 36 is etched and removed as shown in FIG. In this way, the wiring layer 37 composed of the two-layer film of the TiN film 34 and the tungsten film 35 is formed on the insulating layer 32. As described above, according to the etching method of the embodiment of the present invention, the tungsten film 3 is formed at a low temperature of −50 ° C.
By etching 5 and then the TiN film 34 at 25 ° C., it is possible to secure a selectivity with the TiN film 34 when the tungsten film 35 is etched.
Etching rate of TiN film 34,
Since a sufficient selection ratio with respect to the underlying insulating layer 32 can be ensured, process stability and reproducibility can be ensured.

Although chlorine is used as the etching gas for the TiN film 34 in the third embodiment, Cl
A gas containing chlorine such as + Ar, Cl + He, Cl + N ₂ may be used.

[0054]

As described above, in the film forming method according to the present invention, the gas containing tungsten is reduced mainly by diborane to form the first tungsten film, and the gas containing tungsten is added with hydrogen or hydrogen. The second tungsten film is formed by reduction with silane. Therefore, it is possible to continuously form films in the same chamber by simply changing the reaction gas by the CVD method, and it is possible to improve the throughput. Further, the first tungsten film formed by the reduction of diborane is used as the adhesion layer, and the second tungsten film formed thereon is used as the main conductive layer, so that the wiring layer formed has good adhesion with the insulating layer. It is possible to improve and thicken the film without deteriorating the surface morphology.

Furthermore, when the above-mentioned two-layer tungsten film is embedded in the opening formed in the insulating layer on the semiconductor substrate, the first tungsten film formed by reduction of diborane and in contact with the semiconductor substrate at the bottom of the opening is thinned. Because you may
It is possible to suppress the entry of tungsten into the semiconductor substrate. Further, according to the etching method of the present invention, the tungsten film is etched at a low temperature of −20 ° C. or lower and the TiN film is etched at a temperature of 15 ° C. or higher. The selection ratio can be secured, and when etching the TiN film, T
The etching rate of the iN film and the selection ratio to the underlying insulating layer can be sufficiently secured, and the stability and reproducibility of the process can be secured.

Furthermore, in the method of removing the resist film according to the present invention, since the gas containing fluorine is added to the oxygen gas, the reaction product containing tungsten and TiN is effectively removed together with the resist film. can do. Further, according to the etching apparatus of the present invention, the first chamber and the second chamber capable of etching different films are connected by the transfer path capable of reducing the pressure, so that the substrate is transferred from the first chamber to the second chamber. It is possible to prevent condensation due to moisture in the atmosphere on the surface of the substrate by moving the substrate without exposing it to the atmosphere.

Further, since the temperature of the substrate transferred from the first chamber capable of etching at a low temperature to the second chamber capable of etching at a higher temperature is increased, the temperature of the substrate for heating the substrate is increased. Since no special equipment or processing is required, equipment cost can be reduced and throughput can be improved. Further, by using the etching apparatus in which the two chambers are connected, it is possible to suppress an increase in the apparatus cost and to reduce the installation area of the apparatus as compared with the case where two separate etching apparatuses are used. You can

[Brief description of drawings]

1A to 1E are cross-sectional views showing a method of forming a plug using a film forming method of an adhesion layer and a main conductive layer according to a first embodiment of the present invention.

2 (a) and 2 (b) are cross-sectional views showing another example using the film forming method of the adhesion layer and the main conductive layer according to the first embodiment of the present invention.

FIG. 3 is a side view showing a CVD apparatus used in the method for forming the adhesion layer and the main conductive layer according to the first embodiment of the present invention.

4 (a) and 4 (b) are a side view and a plan view showing a configuration of an etching apparatus according to a second embodiment of the present invention.

FIG. 5 is a side view showing a detailed configuration of a first etching chamber in the etching apparatus according to the second embodiment of the present invention.

FIG. 6 is a side view showing a detailed configuration of a second etching chamber in the etching apparatus according to the second embodiment of the present invention.

FIG. 7 is a side view showing a plasma asher used in a method of removing a resist mask according to a third embodiment of the present invention.

8A to 8D are sectional views showing a method of etching a wiring layer and a method of removing a resist mask according to a third embodiment of the present invention.

9A and 9B are cross-sectional views showing a wiring layer using a tungsten film according to a conventional example.

10A and 10B are cross-sectional views showing problems of a wiring layer using a blanket tungsten film according to a conventional example.

[Explanation of symbols]

11,31 Silicon substrate (semiconductor substrate), 12,32 Insulating layer, 13,33 Contact hole (opening), 14,14a, 20 Adhesion layer (first tungsten film), 15,15a, 21 Main conductive layer (first 2 tungsten film), 16,22 plug (embedded layer), 17,23,24,37 wiring layer, 18 interlayer insulating film, 19 via hole (opening), 21 chamber, 22 substrate holder, 34,34a adhesion layer ( TiN film), 35, 35a main conductive layer (tungsten film), 36 resist mask (resist film), 91, 131 chamber, 92, 137 substrate holder, 93, 122 heater (heating means), 94 first gas introduction Port, 95 second gas inlet port, 96, 106 to 110, 126, 139 exhaust port, 97, 100 wafer, 101, 101a first chamber, 102, 102a 2nd chamber, 103, 103a transfer chamber (transfer path), 104, 104a inlet side load lock chamber, 105, 105a outlet side load lock chamber, 111, 121 substrate holder (first electrode), 112 , 123 Refrigerant flow path (cooling means), 113, 125 Second electrode, 114, 126 High frequency power source, 115, 127, 138 Gas introduction port, 124 Substrate temperature adjusting means, 132 Etching chamber, 133 Plasma generating chamber, 134 Micro Wave introduction chamber, 135,136 Partition plate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H01L 21/285 H01L 21/285 C 21/3065 21/302 B 21/88 Q

Claims (10)

[Claims] 1. A step of reducing a gas containing tungsten mainly by diborane to form a first tungsten film on an insulating layer, and a gas containing tungsten being reduced by hydrogen or silane on the first tungsten film. And a step of forming a second tungsten film on the substrate. 2. A step of forming an opening in the insulating layer after forming an insulating layer on a semiconductor substrate, and a gas containing tungsten is reduced mainly by diborane to cover the opening to form a first layer on the insulating layer. 1. A semiconductor device comprising: a step of forming a tungsten film of No. 1; and a step of reducing a gas containing tungsten with hydrogen or silane to form a second tungsten film on the first tungsten film. Production method. 3. The first tungsten film is an adhesion layer that enhances adhesion between the insulating layer and the second tungsten film, and the second tungsten film is a main conductive layer. The method of manufacturing a semiconductor device according to claim 1, wherein the method is the same as that of claim 1. 4. The first tungsten film and the second tungsten film
4. The method for manufacturing a semiconductor device according to claim 1, wherein the tungsten film is blanket tungsten. 5. The manufacturing of the semiconductor device according to claim 4, wherein after the formation of the second tungsten film, the first tungsten film and the second tungsten film are etched and embedded in the opening. Method. 6. The wiring layer is formed according to claim 4, wherein after the formation of the second tungsten film, the first tungsten film and the second tungsten film are selectively etched to form a wiring layer. Manufacturing method of semiconductor device. 7. A step of sequentially forming a titanium nitride film and a tungsten film on a substrate, and etching the tungsten film with a gas containing fluorine while maintaining the substrate at a temperature of −20 ° C. or lower in a reduced pressure atmosphere. And a step of moving the substrate to an etching place of the titanium nitride film without exposing it to the atmosphere after etching the tungsten film, and maintaining the substrate at a temperature of 15 ° C. or higher in a reduced pressure atmosphere with chlorine or chlorine. And a step of etching the titanium nitride film with a gas containing the gas. 8. The method of manufacturing a semiconductor device according to claim 7, wherein the gas containing fluorine is nitrogen trifluoride. 9. The resist film is used as a mask to etch the tungsten film and the titanium nitride film, and then the resist film is removed by exposing it to a mixed gas of a gas containing activated fluorine and a gas containing oxygen. 9. The method for manufacturing a semiconductor device according to claim 7, wherein: 10. A first chamber, comprising a substrate cooling means, for etching a first object to be etched on the substrate under reduced pressure by an activated first gas; heating means and cooling for the substrate. A second chamber for etching the second object to be etched on the substrate under a reduced pressure by the activated second gas, the first chamber and the second chamber, An apparatus for manufacturing a semiconductor device, comprising: a carrier path that holds the state and can move the substrate between them.