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Virtual Image Structure for Defining SubMicron Dimensions

IP.com Disclosure Number: IPCOM000051087D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Barbee, SG: AUTHOR [+2]

Abstract

Minimum images, in the 0.5-2.0 Mum range, which are formed using current lithographic technology for semiconductor fabrication, typically exhibit poor tolerance (approx. +/- 40%). A proposal for the improved forming of micron or sub-micron images derived from one edge of a printed image is illustrated in Figs. 1-7. There the significantly reduced virtual image tolerance is principally determined by control of a thermal oxidation (approx. +/-5 percent).

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Virtual Image Structure for Defining SubMicron Dimensions

Minimum images, in the 0.5-2.0 Mum range, which are formed using current lithographic technology for semiconductor fabrication, typically exhibit poor tolerance (approx. +/- 40%). A proposal for the improved forming of micron or sub-micron images derived from one edge of a printed image is illustrated in Figs. 1-7. There the significantly reduced virtual image tolerance is principally determined by control of a thermal oxidation (approx. +/-5 percent).

The essential steps for virtual image definition are vertical sidewall, definition (Figs. 1,2), thermal oxidation of the polysilicon sidewall (Fig. 3), and removal of the polysilicon layer to form an SiO(2) stud (Fig. 4). The stud is subsequently coated with a photoresist layer (Fig. 5), baked at >/-180 degrees C, and reactive ion etched (RIE) to expose the top of the SiO(2) stud (Fig. 6). Removal of the stud is then completed using a wet etch process, resulting in the virtual image structure of Fig. 7.

Significant features of the image shown in Fig. 7 include minimum image capability of 0.5-1.5 Mum, image tolerance of approx. +/- 10 percent, and vertical resist sidewalls which are stable during subsequent reactive ion etch or Ion implant operations. Formation of the sidewall oxidation using a high pressure oxidation tool permits a low temperature oxidation process. Typical applications of the virtual Image include resistor width, contacts, and lateral trans...