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A Method of Making Wafer Carriers from Silicon Wafers for Dry Etching

IP.com Disclosure Number: IPCOM000033732D
Publication Date: 2004-Dec-23
Document File: 3 page(s) / 56K

Publishing Venue

The IP.com Prior Art Database

Abstract

Many semiconductor dry etching tools can etch silicon wafers in various sizes from 4 inches up to 12 inches. However, it requires changing some fixtures in the tool to fit different sizes of wafers. This is especially true for MEMS fabricators that are trying to apply their equipment for as many customers as possible. The changeover is very time consuming and increases the down time of the machine.

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A Method of Making Wafer Carriers from Silicon Wafers for Dry Etching

Many semiconductor dry etching tools can etch silicon wafers in various sizes from 4 inches up to 12 inches.  However, it requires changing some fixtures in the tool to fit different sizes of wafers. This is especially true for MEMS fabricators that are trying to apply their equipment for as many customers as possible. The changeover is very time consuming and increases the down time of the machine.  In addition, the extra fixtures are often very expensive and need storage places. This proposal would allow the tool to accommodate different sizes of wafers without changing any parts.

This concept describes a method of making wafer carriers from larger silicon wafers for dry etching.  For example, a 4-inch wafer can fit into a carrier that is made of a 6-inch wafer.  The advantages of using this type of carriers are several folds.  Firstly, there is no need for changeover.  It increases the productivity.  Secondly, there is change to the machine setup and the etching characteristics are still the same.  Thirdly, silicon wafer has no contamination issues when used as wafer carriers.  Fourthly, silicon is a strong structure material and the carriers can be used over and over again.  Metal plates tend to warp after long time etching under the ICP plasma.  It would be cost saving for customers.

Introduction:

Dry etching is a very powerful technique for micro systems fabrication.  It is the better alternative to wet etching especially for deep anisotropic etching of silicon or silicon oxide because it provides better etch rate and profiles control.  In many cases, one specific tool needs to accommodate different size of wafers for different customers and applications.  Typically the machine is required to shut down for hours or days to change the parts so that a difference size wafer can fit into the machine.  This procedure is time consuming, reduces productivity, and may even change the machine’s optimum operating conditions.  The easiest way to avoid the changeover is to attach a smaller wafer (e. g.  4 inches) on to a larger carrier (e. g.  6 inches) that will fit the machine.  Since the larger carrier fits the machine, the etching can be done without changeover.  One way to do this is to spin coat a photoresist layer on a 6-in wafer as an adhesive layer and adhere the 4-in wafer on top of the 6-in wafer.  However, there are some drawbacks for this approach.  Firstly, the photoresist creates a thermal barrier that prevents effective cooling from the backside of the wafer.  Secondly, the etching...