VACANCY ENHANCED DIFFUSION IN SILICON. EFFECTS OF IRRADIATION AND OF CHEMICAL IMPURITIES
In silicon, the diffusion of most electrically active impurities is caused by a vacancy mechanism and by the introduction of excess vacancies created by irradiation. To observe this effect, wafers of n-type silscon containing a p-- -n junction at 6 mu from the surface are bombarded with 275 kev protons. This junction was obtained through gallium diffusion.The bombardment temperature was between 900 and 1100 deg C. It is observed that, in the irradiated region, the junction depth increases. Thus, the gallium has diffused inwards the crystal at a larger rate than in the non-irradiated region. However, since the penetration of 275 kev protons in silicon is only 3 mu , one must suppose that vacancies diffuse, after being created over a few microns, to enhance gallium diffusion at the junction location. Other explanations are possible, such as the effect of hydrogen injected by the proton beam, or the effect of thermal stresses. The observed advance of the diffusion frontm in these experiments is similar to the advance of the collector junction below the emitter in the fabrication of double- diffused silicon transistors by the oxide masking-technique. A possible explanation would follow the same lines; the introduction of donors, to form the emitter, increases the local vacancy concentration, by ionization interaction. These vacancies would enhance the acceptor diffusion rate. These effects can be used to obtain information relative to the concentration of thermal vacancies and to the diffusion length, lifetime, and annihilation mechanism of excess vacancies. (auth)
- Research Organization:
- Ecole Normale Superieure, Paris
- NSA Number:
- NSA-16-013652
- OSTI ID:
- 4802440
- Journal Information:
- Discussions Faraday Soc., Journal Name: Discussions Faraday Soc. Vol. Vol: No. 31
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Proton-enhanced diffusion and vacancy migration in silicon
EFFECTS OF PROTON IRRADIATION ON THE PROPERTIES OF SILICON
Related Subjects
ANNIHILATION
CARRIERS
DEFECTS
DIFFUSION
DIFFUSION LENGTH
ELECTRIC CHARGES
EMISSION
FRANCE
GALLIUM
HIGH TEMPERATURE
HYDROGEN
IMPURITIES
INJECTION
INTERACTIONS
IONIZATION
IRRADIATION
JUNCTIONS
LATTICES
LIFETIME
METALS, CERAMICS, AND OTHER MATERIALS
PROTON BEAMS
RADIATION EFFECTS
SEMICONDUCTORS
SILICON
THERMAL STRESSES
TRACER TECHNIQUES
TRANSISTORS