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Title: Method for making circular tubular channels with two silicon wafers

A two-wafer microcapillary structure is fabricated by depositing boron nitride (BN) or silicon nitride (Si.sub.3 N.sub.4) 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/HNO.sub.3 /CH.sub.3 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.
 [1];  [2]
  1. (Antioch, CA)
  2. (Campbell, CA)
Issue Date:
OSTI Identifier:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5575929
Contract Number:
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Country of Publication:
United States
method; circular; tubular; channels; silicon; wafers; two-wafer; microcapillary; structure; fabricated; depositing; boron; nitride; bn; separate; crystal-plane; 100; 110; crystal; orientation; photolithography; photoresist; create; exposed; deposition; plasma; etching; slit; entry; created; path; desired; ultimate; acetone; remove; isotropic; etch; hf; hno; cooh; erodes; trench; layer; channel; half-circular; section; formed; line; wet; aligned; bonded; face-to-face; complete; plasma etching; silicon nitride; boron nitride; silicon wafer; wet etching; silicon wafers; tubular channel; plasma etch; crystal orientation; /216/