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Phosphorus Oxynitride Masking Material

IP.com Disclosure Number: IPCOM000088633D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Li, PC: AUTHOR [+4]

Abstract

The technique for fabricating holes in silicon (Si), by either etching silicon or converting the desired hole geometry to porous silicon and removing the porous silicon, is strongly dependent on the ability of the masking material to survive the etching step. For example, if Si(3)N(4) is used to define a region being converted to porous Si, special care must be taken to prevent the Si(3)N(4) from being removed in the porous process which uses 10-50% HF. The special care is either short porous conversion times, or very thick Si(3)N(4) films. The very thick film can severely stress the silicon and result in dislocations in the silicon. Other organic masking materials which are insoluble in HF solutions lack adequate adhesion to the wafer and consequently result in oversized holes.

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Phosphorus Oxynitride Masking Material

The technique for fabricating holes in silicon (Si), by either etching silicon or converting the desired hole geometry to porous silicon and removing the porous silicon, is strongly dependent on the ability of the masking material to survive the etching step. For example, if Si(3)N(4) is used to define a region being converted to porous Si, special care must be taken to prevent the Si(3)N(4) from being removed in the porous process which uses 10-50% HF. The special care is either short porous conversion times, or very thick Si(3)N(4) films. The very thick film can severely stress the silicon and result in dislocations in the silicon. Other organic masking materials which are insoluble in HF solutions lack adequate adhesion to the wafer and consequently result in oversized holes.

A material that has excellent adhesion to silicon, silicon dioxide, etc., and is insoluble in 50% HF, HF-HNO(3), and most other acids, alkalis, or etchants used for all silicon based technologies is phosphorus oxynitride. This compound is produced by chemical vapor deposition techniques at temperatures as low as 400 degrees C.

A use of this material is in ink jet nozzles wherein silicon is the nozzle material. A thin film of phosphorus oxynitride is deposited onto the silicon surface. The desired configuration of the nozzle opening is defined by reactive ion etching. The silicon is then anodically etched to open holes using any concentration of HF fo...