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Gettering Diffusion with Etch Back

IP.com Disclosure Number: IPCOM000086055D
Original Publication Date: 1976-Jul-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Strudwick, TH: AUTHOR

Abstract

Described is a process combining the formation of a PN junction and gettering for obtaining improved bulk and surface recombination velocities.

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Gettering Diffusion with Etch Back

Described is a process combining the formation of a PN junction and gettering for obtaining improved bulk and surface recombination velocities.

This process can be illustrated by assuming a desired device which has:

1) Requirements of reliability, yield or performance which are adversely affected by high bulk and/or surface recombination velocities; and,

2) Design requirements dictating a phosphorous diffusion characterize by a C(s)~ 5 x 10/19/ atoms/cc, an X(j) - 0.5-1 micron, an R(s2) ~ 20 ohm/sq, and a 10/16/ atoms/cc boron doped starting wafer of <100> orientation.

The conventional approach to the solution of this problem would be the utilization of a two-step open tube, or evacuated quartz capsule, diffusion to obtain the required C(s) followed by back surface application of a metal (e.g., tin) and subsequent refiring at 900 degrees C to getter undesirable fast diffusing bulk impurities.

In contrast, this process utilizes a single POC1(3) diffusion at about 900 degrees C with a C(s) >/- 10/21/ atoms/cc for the time required to obtain an initial X(j)1, followed by partial removal ( >/- 0.4 mu m) of the diffused layer with a controlled nonpreferential etch (e.g., a 250/1-HNO(3)/HF mixture) to obtain the final X(j)2. A subsequent gettering step is unnecessary inasmuch as the dislocation network formed during the high C(o) phosphorous diffusion performs this function, and is then subsequently removed by the etchant, thereby ful...