Production-scale flux-free bump reflow using electron attachment

Journal of Electronic Materials, 2001

Many of the semiconductor manufacturing steps require thermal processing for the deposition and growth of films, induction of reactions, and annealing of defects by energetic processes such as implantation and plasma processing. Historically, thermal processing steps during silicon (Si) wafer fabrication have been carried out in a furnace. A furnace depends on equilibrium heat-transfer conditions to ensure uniform heating of wafers placed in it. This limits the rate of temperature rise in the furnace due to limitations governing uniform heat transfer across each wafer placed in the furnace. Most of the furnaces normally maintain a constant temperature across the flat zone (less than 0.25°C 1 ). Such temperature accuracy enables molecular level control of the process chemistry that relates directly to precise film thickness, junction depth, and dopant concentrations. Such a level of consistent processing across large wafer batches can be directly linked to yield device parameter consistency and gives a significant advantage over a nonisothermal cold-wall technology. Rapid thermal processing (RTP), on the other hand, operates in an inherently transient mode where the various components of the reactor are not in thermal equilibrium with each other.

ie.utcluj.ro

Abstract: Electron beam have many special properties which make them particularly well suited for use in materials handling through melting, welding, surface treatment, etc., taking into account that this manufacturing is performed in vacuum. The use of electron beam for ...

Journal of Instrumentation, 2010

Conventional bumping processes used in the fabrication of hybrid pixel detectors for High Energy Physics (HEP) experiments use electroplating for Under Bump Metallization (UBM) and solder bump deposition. This process is laborious, involves time consuming photolithography and can only be performed using whole wafers. Electroplating has been found to be expensive when used for the low volumes which are typical

Solid State Technology

Despite intuition, application of an electric field does have a measurable effect on the movement of metallic contaminants in gas in a wafer processing thermal process. Research has shown that the phenomenon of positive surface ionization can give rise to significant electric field effects on the gas-phase transport of ionizable atoms such as alkali metals, even at very low fractional ionizations and modest electric fields. In addition, such application of an electric field can also reduce contamination by transition metals at high temperatures.

1997

An investigation of the plasma nitriding mechanism under intensified conditions (average particle energy up to 1200 eV) was carried out using a triode configuration. The significance of the different physical processes taking place during intensified plasma nitriding, such as sputtering, implantation, defect generation, redeposition and diffusion were investigated experimentally, while theoretical predictions were obtained by using the TRIM (transport of ions in matter) code. A titanium-base alloy was selected as the substrate material. Sputtering yield in an inert atmosphere was found to exhibit three regimes as a function of incoming particle energy. The low energy and high energy regimes were found to be in agreement with the theoretical predictions while the intermediate regime showed a reduced level of sputtering yield independent of energy. This was the first time that such reduced sputtering yield was observed and was attributed to the onset of other physical processes such a...

Journal of Vacuum …, 2006

The substantial reductions in anneal times, such as in flash-assist rapid thermal processing ͑fRTP͒, place considerably more emphasis on the initial condition of the wafer, which may assume a greater role in the dictating diffusion product ͑Dt͒. Investigations have been conducted on the effect of low-temperature preanneals prior to fRTP on the extended defect nucleation and evolution and on boron activation. Czochralski grown n-type silicon wafers are preamorphized with 8 Ge + ions at a constant dose of 1 ϫ 10 15 cm -2 and then implanted with 1 keV, 1 ϫ 10 15 cm -2 B. Low-temperature furnace anneals are performed at 500 °C for 30 min and the wafers subsequently subjected to flash-assist RTP anneals in the range 1000-1300 °C. Four-point probe measurements indicate that the low-temperature anneal results in higher sheet resistance values. Plan-view transmission electron microscopy, secondary-ion-mass spectrometry, and Hall-effect measurements revealed no substantial differences in defect structure, junction depth, or mobility. However, the carrier density was found to be higher for those wafers which were preannealed.

Solar Energy Materials and Solar Cells, 2002

A new process combining inductive plasma torch and electromagnetic stirring of molten silicon in a cold crucible has been developed to refine upgraded metallurgical silicon. The addition of reactive gases to the plasma leads to volatilisation of impurities at the liquid silicon surface. The concentration of boron impurities decreased from 15 ppmw in the raw material to less than 2 ppmw after the plasma treatment. The most volatile form of boron was BOH, which was obtained by simultaneous treatment with oxygen and hydrogen. The limitation in boron volatilisation is due to the formation, at high oxygen flow rate, of a silica layer at the surface of the molten silicon, which results in a dramatic drop of the volatilisation rate. In contrast to boron, the concentration of phosphorus was reduced by only a factor of two, although the remainder seems to be electrically neutral. Thermodynamic studies suggest that phosphorus could be trapped as phosphate in combination with metallic impurities. Cells made of material produced using this technique exhibited a conversion efficiency of 12.4%. r

Applied Physics Letters, 1993

Applied Surface Science, 2002

The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis results are compared with electron dose dependent secondary electron and electron stimulated desorption yield measurements.

Proceedings Particle Accelerator Conference, 1995

An industrial electron beam accelerator has been developed at Samsung Heavy Industries with the collaboration of Seoul National University and Russian Budker Institute of Nuclear Physics. The accelerator is a high voltage accelerator using rectifiers and able to deliver 40 mA of 1 MeV electrons in CW mode. Functionally, the accelerator is an electron irradiation processing device and an electron beam scanning system is employed for the uniform irradiation of the electron beam through the extraction window of the size 980 mm x 75 mm. The industrial applications of the electron irradiation processes include combustion flue gas purification process, treatment of industrial waste water containing refractory pollutant, treatment of semiconductor devices, and radio-chemical processes. The major features of the device and its industrial applications will be described.