Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
2000-01-13
2001-02-13
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C216S012000
Reexamination Certificate
active
06187690
ABSTRACT:
TECHNICAL FIELD
The invention pertains to methods of manufacturing semiconductive wafers and to methods of manufacturing semiconductive material stencil masks.
BACKGROUND OF THE INVENTION
Ion and electron beam lithographic systems utilize a stencil mask to pattern a resist coated target. These stencil masks typically comprise a substrate and a pattern of openings formed through the substrate. Commonly, the substrate will be formed of silicon. However, other deposited or grown materials, such as SiC, SiN and BN can also be used to form portions of the substrate.
The formation of a pattern of openings extending through substrates comprising silicon, SiC, SiN and/or BN can be quite challenging as such substrates are frequently thin and brittle. Accordingly, it would be desirable to develop alternative methods of forming a pattern of openings within such substrates.
SUMMARY OF THE INVENTION
The invention pertains to a novel method of forming stencil masks. The invention pertains particularly to methods of forming openings in semiconductive materials and to methods of determining if such openings extend entirely through a semiconductive material.
In one aspect, the invention encompasses a method for manufacturing a semiconductive wafer. A semiconductive material wafer having a front surface and a back surface is provided. The front surface is contacted with a first fluid. The back surface is contacted with a second fluid different than the first fluid. At least one of the first and second fluids is configured to etch the semiconductive material of the wafer. At least one of the first and second fluids has a measurable component at a first concentration which is different than any concentration of said measurable component in the other of the first and second fluids. The semiconductive wafer is etched with at least one of the first and second fluids configured to etch the semiconductive material. The measurable component concentration is monitored in at least one of the first and second fluids to ascertain if the etching has formed an opening extending completely through the substrate.
In another aspect, the invention encompasses a method for manufacturing a semiconductive material stencil mask. A semiconductive material stencil mask substrate having a front surface and a back surface is provided. The front surface is contacted with a substantially inert solution having a first pH. The back surface is contacted with an etchant having a second pH. The second pH is different than the first pH. The pH of at least one of the inert solution or the etchant is monitored to ascertain if the etchant has formed an opening extending completely through the substrate.
In another aspect, the invention encompasses a method for manufacturing a semiconductive material stencil mask. A semiconductive material wafer having a front surface and a back surface is provided. One of the front surface or the back surface is contacted with an inert liquid solution. An other of the front surface or the back surface is contacted with an etchant liquid solution. At least one of the inert liquid solution or the etchant liquid solution has a measurable component at a first concentration which is different than any concentration of said measurable component in an other of the inert liquid solution or the etchant liquid solution. The measurable component concentration in at least one of the inert solution or the etchant liquid solution is monitored to ascertain if the etchant liquid solution has formed an opening extending completely through the substrate.
In another aspect, the invention encompasses a method for manufacturing a semiconductive material stencil mask. A semiconductive material stencil mask substrate having a front surface and a back surface is provided. An n-type conductivity enhancing dopant is provided proximate the front surface of the substrate. Openings are etched into the front surface and through the n-type conductivity enhancing dopant. The front surface is contacted with an inert solution. The back surface is contacted with an etchant. A positive potential is applied to the front surface. A negative potential is applied to the back surface. Etching is conducted through the back surface and to the openings. The etchant solution and inert solution mix after the etchant etches to the openings. A chemical characteristic of the etchant or the inert solution is monitored to determine approximately when the etchant mixes with the inert solution.
In another aspect, the invention encompasses a method for manufacturing a semiconductive material stencil mask. A semiconductive material stencil mask substrate having a front surface and a back surface is provided. An n-type conductivity enhancing dopant is provided proximate the front surface of the substrate. Openings are etched into the front surface and through the n-type conductivity enhancing dopant. The front surface is contacted with an inert solution. The back surface is contacted with an etchant. A positive potential is applied to the front surface. A negative potential is applied to the back surface. An etch is conducted through the back surface and to the openings. The etchant solution and inert solution mix after the etchant etches to the openings. A current between the front surface of the substrate and the back surface of the substrate is monitored. The current changes after the etchant solution mixes with the inert solution.
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Micro)n Technology, Inc.
Umez-Eronini Lynette T.
Utech Benjamin L.
Wells St. John Roberts Gregory & Matkin
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