Browse Prior Art Database

Double Field Implant

IP.com Disclosure Number: IPCOM000080676D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Antipov, I: AUTHOR [+2]

Abstract

During formation of the field oxide in complementary metal-oxide semiconductor device processing by oxidation, boron in the P-pocket field is depleted, and at the end of the process boron concentration in the field is lower than in the gate region of the N-channel devices. Thus, the field region in the P pocket is prone to surface inversion, especially if any appreciable charge level is allowed to accumulate in these regions in subsequent processing, such as sputtering.

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Double Field Implant

During formation of the field oxide in complementary metal-oxide semiconductor device processing by oxidation, boron in the P-pocket field is depleted, and at the end of the process boron concentration in the field is lower than in the gate region of the N-channel devices. Thus, the field region in the P pocket is prone to surface inversion, especially if any appreciable charge level is allowed to accumulate in these regions in subsequent processing, such as sputtering.

In this process, additional impurity is introduced into the field region, in order to compensate for the impurity depletion resulting in oxidation of the silicon.

In this process, on an N- silicon substrate 8 a first SiO(2) layer 10 is formed, preferably by oxidation, a second layer 12 of Si(3)N(4) deposited on layer 10, and a third SiO(2) layer 14 deposited on 12 by chemical vapor deposition techniques. Layer 14 is sufficiently thick to block off low energy ion implants of the subsequently desired impurity. With the mask defining all device areas, regions of layer 14 are removed to expose layer 12. The photoresist, not shown, is then removed and the exposed areas of Si(3)N(4) layer 12 removed by dip etching. The resultant structure is illustrated in Fig. 1.

A layer of photoresist 16 is deposited and exposed with a mask defining the P-pocket areas. A low-energy boron implant is performed into regions that are not covered by either photoresist 16 or SiO(2) layer 14. The structu...