Browse Prior Art Database

Narrow Line Width Masking Method

IP.com Disclosure Number: IPCOM000086875D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Pogge, HB: AUTHOR

Abstract

Narrow line widths, in the range of 1.0 micron or less, are produced by extending standard photolithography techniques and avoiding the need to use special techniques such as E-beam or X-ray lithography.

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Narrow Line Width Masking Method

Narrow line widths, in the range of 1.0 micron or less, are produced by extending standard photolithography techniques and avoiding the need to use special techniques such as E-beam or X-ray lithography.

Silicon wafer 1 of Fig. 1 is covered with a layer of porous silicon 2 having a relatively low porosity in the range of about 30 to 40%. The porous silicon layer is covered by pyrolytic silicon dioxide layer 3 and a top layer of photoresist 4 into which a 2.0 micron window is placed using conventional photolithography. The apertured photoresist layer 4 then is used as a mask to etch corresponding windows through the underlying pyrolytic oxide and porous silicon layers 3 and 2, respectively, as shown in Fig. 2.

The effective line width of the apertured masking structure of Fig. 2 is reduced below the value (approximately 2.0 microns) achievable using standard photolithographic techniques by removing the photoresist and thermally oxidizing the structure of Fig. 2 to yield the structure of Fig. 3. Oxidation of the porous silicon layer 2 proceeds at a much more rapid rate than the oxidation of the underlying substrate 1. By controlling the oxidation parameters, the window is controllably reduced to a desired line width, for example, 1.0 micron or less, as indicated in Fig. 3. The resulting structure of Fig. 3 may be used, for example, for the etching of narrow grooves into the surface of substrate 1 for device isolation purposes, as su...