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Self-Alignment Technique for Semiconductor Processing

IP.com Disclosure Number: IPCOM000061427D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Leach, MA: AUTHOR

Abstract

By means of grazing angle vacuum deposition of material upon the edges of image openings in masking materials used in defining a first element (e.g., a base region of a transistor), a second smaller element region (e.g., an emitter region) is defined inside of and in alignment with the first element. This technique, which can eliminate many photo process steps and provide very close tolerance alignment, may be used whenever (a) image openings for defining the first element are uniformly small relative to the thickness of the masking material, and (b) the process used for creating the second element is a line-of-sight process, e.g., an ion implantation or a vacuum deposition process.

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Self-Alignment Technique for Semiconductor Processing

By means of grazing angle vacuum deposition of material upon the edges of image openings in masking materials used in defining a first element (e.g., a base region of a transistor), a second smaller element region (e.g., an emitter region) is defined inside of and in alignment with the first element. This technique, which can eliminate many photo process steps and provide very close tolerance alignment, may be used whenever (a) image openings for defining the first element are uniformly small relative to the thickness of the masking material, and (b) the process used for creating the second element is a line-of-sight process, e.g., an ion implantation or a vacuum deposition process. The figure shows the final step of ion implantation of an n-type dopant (represented by arrows II) to form emitter regions N inside of previously ion-implanted base regions P in the n-type substrate 2. During the implantation of the p-type material, the image openings in the masking materials 4 and 6 (e.g., photoresist and silicon nitride, respectively) define the regions to be implanted. Layer 8, e.g., aluminum, is subsequently vacuum deposited by utilization of a suitable large diameter ring source or by rotation of the substrate relative to a small source so as to provide evaporant arrival direction, as represented by arrows E, at all grazing angles to the substrate. The resultant deposited film 8 reduces the width of the origin...