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This process eliminates a masking step in the formation of an ion-implanted emitter in semiconductor bipolar transistors.
English (United States)
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Ion Implanting an Emitter
This process eliminates a masking step in the formation of an ion-implanted
emitter in semiconductor bipolar transistors.
In Fig. 1, base region 5 has been formed in N- substrate 2. Isolation regions
4 are provided in standard fashion for isolating base contact 20 from collector
contact 21 and Schottky barrier diode contact 22. Protective layers of silicon
dioxide 6 and 8 and silicon nitride are formed atop thy substrate during the
processing steps. Oxide layer 8 is substantially thicker than oxide layer 6.
Openings 20, 21 and 22 are formed by simultaneously etching these areas, with
photoresist layer 10 being used to protect the emitter region to be formed.
In the next step, illustrated in Fig. 2, a blocking mask photoresist layer 14 is
deposited in the contact regions, and an aperture 23 is made in layer 6 to open
the emitter region. The emitter is then formed by ion implantation in standard
This process prevents ion-beam penetration in all but the emitter area while
not causing contamination in the protected areas.
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