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US 6,724,967 B2Granted
Method of making a functional device with deposited layers subject to high temperature anneal
AssigneeDALSA Semiconductor Inc.
InventorsLuc Ouellet, Annie Dallaire
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Abstract
A method is disclosed for making a device having one or more deposited layers and subject to a post deposition high temperature anneal. Opposing films having similar mechanical properties are deposited on the front and back faces of a wafer, which is subsequently subjected a high temperature anneal. The opposing films tend to cancel out stress-induced warping of the wafer during the subsequent anneal.
Claims11
A method of making an optical multiplexer/demultiplexer comprising the steps of:
- providing a silicon wafer having a front and back face;
- depositing a first silica film having a first thickness on said front face td protect said front face during handling of said wafer;
- depositing a second silica film having a second thickness greater than said first thickness on said back face;
- exposing said wafer to an etchant to remove said first silica film from said front face, said etchant reducing the thickness of said second silica film to a third thickness substantially equal to said second thickness less said first thickness;
- depositing a third silica film forming an optical waveguide on said front face and having said third thickness;
- and
- subsequently subjecting said wafer to said high temperature anneal whereby said second and third silica films act in opposition to prevent stress-induced warping of said wafer from occurring during said high temperature anneal.
4 more elements
Dependencies are inferred from the claim text.