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Method of Controlling Edge Angles in a Polysilicon Layer

IP.com Disclosure Number: IPCOM000046061D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Goessler, W: AUTHOR [+6]

Abstract

A method is described for controlling the edge angle in a polysilicon layer at 25 + 10Œ, wherein a borosilicate glass layer is used as an auxiliary layer in a photolithographic process.

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Method of Controlling Edge Angles in a Polysilicon Layer

A method is described for controlling the edge angle in a polysilicon layer at 25 + 10OE, wherein a borosilicate glass layer is used as an auxiliary layer in a photolithographic process.

On a silicon substrate, a silicon dioxide layer is grown on which a silicon nitride layer is deposited. A polysilicon field shield is deposited on the nitride layer and boron-doped in an open diffusion. The borosilicate glass layer thus formed on the polysilicon field shield is used as an auxiliary layer in the subsequent photolithographic process. As the etch rate of the borosilicate glass layer is much higher than that of polysilicon, simultaneous etching of both layers through a photoresist mask at a constant ratio of the etch rates inevitably leads to constant edge angles. The relation applicable is tg etch rate/borosilicate glass/ : etch rate/polysilicon/.

This method permits edge angles of 25 + 10OE, whereas when a polysilicon layer is etched without a borosilicate glass layer, steeper angles of the order of 60 to 70OE are obtained.

The method is suitable for all boron-doped polysilicon processes.

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