Semiconductor device manufacturing: process – Radiation or energy treatment modifying properties of...
Patent
1997-03-03
1998-05-12
Niebling, John
Semiconductor device manufacturing: process
Radiation or energy treatment modifying properties of...
438530, 148DIG3, 148DIG4, 148DIG80, 148DIG90, 148DIG92, H01L 21324
Patent
active
057504431
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND ART
There is known a technique of reducing lifetime of carriers by diffusing a heavy metal species such as gold or platinum or radiating a corpuscular beam such as an electron beam, an X-ray and a proton beam, in order to provide a pn junction semiconductor device having a high-speed switching responsibility.
Studies have being made for a long time on the method of diffusing a heavy metal such as gold or platinum into a semiconductor layer. However, there is a problem that the correlation (h.sub.FE -t.sub.stg) between current amplification factor and carrier build-up time period is not necessarily desirable for transistors, etc., because of difficulty in controlling and making uniform for diffusion variables. Furthermore, cares have to be taken for prevention against contamination of a treatment apparatus for use in post-treatment, thus imposing much labor on the process management.
Meanwhile, the method of radiating a corpuscular beam is to radiate a high-energy corpuscular beam so that deep levels of defects are created in a semiconductor layer crystal to thereby reduce lifetime of carriers. These crystal defects once created are restored by a comparatively low temperature of heat treatment, diminishing the effect. As a consequence, there is restriction that such heat treatment has to be carried out at a later process stage in the manufacture of a semiconductor device.
In also the method of corpuscular-beam radiation to reduce carrier lifetime for reducing carrier build-up time period (shortening switching time period), there is still a problem that the correlation (h.sub.FE -t.sub.stg) between current amplification factor and carrier build-up time period is not satisfactory. That is, where the carrier lifetime is reduced to speeding up the switching time period t.sub.off, the dopant concentration of the collector layer is increased, giving rise to degradation in electrical characteristics such as current amplification factor h.sub.FE.
It is the object of the present invention to solve the abovestated problems and provide a semiconductor device which is improved in the relation of current amplification factor versus switching time period to provide a high speed of switching characteristic as well as excellent electrical characteristic such as current amplification factor.
DISCLOSURE OF THE INVENTION
As a result of ardent consideration for obtaining a semiconductor device which satisfies both the high-switching characteristics and the improvement on electrical characteristics such as current amplification factor, the present inventor has found that a semiconductor device, possessing a high-switching speed characteristic while maintaining electric characteristics such as current amplification factor, is obtained by subjecting a semiconductor substrate to a heat treatment with rapid heating-up prior to radiation of a corpuscular beam such as an electron beam.
A method of manufacturing a semiconductor device of the present invention, wherein a corpuscular beam is radiated to a semiconductor substrate to create crystal defects therein, is characterized in that the semiconductor substrate is subjected to a heat treatment wherein rapid heating-up is done in a process prior to that of carrying out of the radiation with a corpuscular beam.
Here, the heat treatment with rapid heating-up means heating with temperature rising at a rapid rate, e.g., heating-up from a room temperature to approximately 850.degree. C. is done in 10 minutes or shorter, wherein an optical lamp such as an infrared-ray lamp, a discharge lamp, and laser beam, or high-frequency microwave radiation or otherwise a heating furnace with low thermal capacity is used as a heating device. The heating device with an optical lamp or a high-frequency radiation is in particular preferred because of low thermal capacity.
According to the present invention, since a heat treatment with rapid heating-up is performed prior to radiation of a corpuscular beam such as an electron beam, cluster nuclei such as SiO.sub.4 (SiO.sub.n (n>2)) is form
REFERENCES:
patent: 4566913 (1986-01-01), Brodsky et al.
patent: 4794217 (1988-12-01), Quan et al.
patent: 5279973 (1994-01-01), Suizu
patent: 5502010 (1996-03-01), Nadahara et al.
Niebling John
Pham Long
Rohm & Co., Ltd.
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