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Photoresist Reactive Ion Etching at Reduced Etch Rate

IP.com Disclosure Number: IPCOM000062428D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Bayer, T: AUTHOR [+2]

Abstract

A cathode material for dry etching a trilayer structure is proposed, by means of which an an etch rate ratio of photoresist/SiNO or Si3N4 layer of < 1 is obtained. The figure shows a mask for a trilayer process. The mask is positioned on a wafer and was produced from a thick photoresist layer, an SiNO or an Si3N4 layer and a thin photoresist layer as the top layer. A high resolution necessitates a low etch rate for the photoresist mask, so that at a given resist thickness, deep structures can be etched into the underlying material. Normally, however, the etch rate of a photoresist, such as AZ 1350 (Shipley Company), is about 30% higher than that of an SiNO or an Si3N4 layer. There is no known etch gas, by means of which an etch rate ratio of resist/SiNO or Si3N4 layer of < 1 could be obtained.

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Photoresist Reactive Ion Etching at Reduced Etch Rate

A cathode material for dry etching a trilayer structure is proposed, by means of which an an etch rate ratio of photoresist/SiNO or Si3N4 layer of < 1 is obtained. The figure shows a mask for a trilayer process. The mask is positioned on a wafer and was produced from a thick photoresist layer, an SiNO or an Si3N4 layer and a thin photoresist layer as the top layer. A high resolution necessitates a low etch rate for the photoresist mask, so that at a given resist thickness, deep structures can be etched into the underlying material. Normally, however, the etch rate of a photoresist, such as AZ 1350 (Shipley Company), is about 30% higher than that of an SiNO or an Si3N4 layer. There is no known etch gas, by means of which an etch rate ratio of resist/SiNO or Si3N4 layer of < 1 could be obtained. Tests have shown that such an etch rate ratio can be obtained by means of a suitable cathode material. A favorable cathode material is a polycarbonate, such as MAKROLON* or LEXAN**. The plasma parameters for reactive ion etching were etch gas: 20 ml CF4 pressure: 1.2 x 10-2 mbar MAKROLON cathode etch rate (SiNO) = 54 nm/min. etch rate (AZ 1350 resist) =
17.3 nm/min. etch rate ratio SiNO/AZ 1350 resist = 3.12. With a MAKROLON or LEXAN cathode, the photoresist layer is etched by a factor 3 slower than with an SiO2 cathode. * Trademark of Bayer Corporation. ** Trademark of General Electric Corporation.

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