Method for making circular tubular channels with two silicon wafers
First Claim
1. A method for making circular tubular channels with two silicon wafers, comprising:
- coating a first surface of a first silicon wafer with a first protective coating resistant to etching;
coating a second surface of a second silicon wafer with a second protective coating resistant to etching;
patterning a first slit entry in said first protective coating along a narrow path defined for a wider tubular channel in said first surface of said first silicon wafer;
patterning a second slit entry, which is a mirror-image of said first slit entry, in said second protective coating along said narrow path defined for said tubular channel in said second surface of said second silicon wafer;
isotropically etching said first and second surfaces of said first and second silicon wafers through said first and second slit entries such that said first and second silicon wafer are eroded equally in all directions from said slit entries, wherein respective halves of said tubular channel are formed, each having a semicircular cross section; and
joining together said first and second silicon wafers at said first and second surfaces with said respective halves of said tubular channel aligned to produce an overall circular cross section for said tubular channel.
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Accused Products
Abstract
A two-wafer microcapillary structure is fabricated by depositing boron nitride (BN) or silicon nitride (Si3 N4) on two separate silicon wafers (e.g., crystal-plane silicon with [100] or [110] crystal orientation). Photolithography is used with a photoresist to create exposed areas in the deposition for plasma etching. A slit entry through to the silicon is created along the path desired for the ultimate microcapillary. Acetone is used to remove the photoresist. An isotropic etch, e.g., such as HF/HNO3 /CH3 COOH, then erodes away the silicon through the trench opening in the deposition layer. A channel with a half-circular cross section is then formed in the silicon along the line of the trench in the deposition layer. Wet etching is then used to remove the deposition layer. The two silicon wafers are aligned and then bonded together face-to-face to complete the microcapillary.
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Citations
7 Claims
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1. A method for making circular tubular channels with two silicon wafers, comprising:
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coating a first surface of a first silicon wafer with a first protective coating resistant to etching; coating a second surface of a second silicon wafer with a second protective coating resistant to etching; patterning a first slit entry in said first protective coating along a narrow path defined for a wider tubular channel in said first surface of said first silicon wafer; patterning a second slit entry, which is a mirror-image of said first slit entry, in said second protective coating along said narrow path defined for said tubular channel in said second surface of said second silicon wafer; isotropically etching said first and second surfaces of said first and second silicon wafers through said first and second slit entries such that said first and second silicon wafer are eroded equally in all directions from said slit entries, wherein respective halves of said tubular channel are formed, each having a semicircular cross section; and joining together said first and second silicon wafers at said first and second surfaces with said respective halves of said tubular channel aligned to produce an overall circular cross section for said tubular channel. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification