| US 7,572,708 B1 | ||
| Utilization of doped glass on the sidewall of the emitter window in a bipolar transistor structure | ||
| Jeff A. Babcock, Sunnyvale, Calif. (US); Steve Adler, Cape Elizabeth, Me. (US); Todd Thiebeault, Gorham, Me. (US); and Jamal Ramdani, Scarborough, Me. (US) | ||
| Assigned to National Semiconductor Corporation, Santa Clara, Calif. (US) | ||
| Filed on Mar. 08, 2007, as Appl. No. 11/715,634. | ||
| Int. Cl. H01L 21/331 (2006.01) | ||
| U.S. Cl. 438—369 [257/E21.149] | 18 Claims |
| 9. A method of forming a bipolar transistor structure, the bipolar transistor structure including a collector region having
a first conductivity type and formed in a semiconductor substrate, a base region formed on the collector region and having
a second conductivity type that is opposite the first conductivity type, and a first layer of dielectric material formed on
the base region and having a first emitter window opening formed therein, the first emitter window opening defining sidewalls
of the first layer of dielectric material that extend from an upper surface of the first layer of dielectric material to an
upper surface of the base region to expose an upper surface area of the base region, the method comprising:
forming a second layer of dielectric material over the first layer of dielectric material;
forming a second emitter window opening in the second layer of dielectric material, the second emitter window opening being
aligned with the first emitter window opening and defining sidewalls of the second layer of dielectric material that extend
from an upper surface of the second layer of dielectric material to an upper surface of the first layer of dielectric material
to expose a perimeter surface area of the first layer of dielectric material that extends around the perimeter of the first
emitter window opening;
forming a doped silicate glass layer on the second layer of dielectric material and extending into the first and second emitter
window openings;
removing doped silicate glass from the first and second emitter window openings to define silicate glass spacers on the sidewalls
of the second layer of dielectric material and on the perimeter surface area of the first layer of dielectric material and
extending to a perimeter edge of the first emitter window opening; and
forming a conductive emitter having the first conductivity type and that extends into the first ands second emitter window
openings and into contact with the doped silicate glass spacers, the sidewalls of the first layer of dielectric material and
the exposed upper surface area of the base region.
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