Three dimensional etching process

• US 6,682,657 B2
• Filed: 07/07/1998
• Issued: 01/27/2004
• Est. Priority Date: 01/10/1996
• Status: Expired due to Fees

• Current Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Dean, Anthony B, Dutton, David T
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US09/101,306
• Publication Number:
  US 20030057177A1
• Time in Patent Office: 2,030 Days
• Field of Search: 216/2, 216/11, 216/24, 216/26, 216/41, 216/49, 216/64, 216/67, 216/72, 216/74, 257/55, 257/95, 257/98, 257/189, 257/425, 257/432, 257/441, 257/615, 257/629, 257/631, 257/636, 257/638, 257/642, 257/646, 65/37, 65/39
• US Class Current: 216/2
• CPC Class Codes: G02B 3/0012 characterised by the manufacturing method
• CPC Class Codes: G02B 3/0018 Reflow, i.e. characterized by the step of melting microstructures to form curved surfaces, e.g. manufacturing of moulds and surfaces for transfer etching
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

Abstract

A method of forming three-dimensional structures on a substrate by a single reactive ion each run whereby a mask is formed on said substrate before a series of iterations are carried out, each iteration including a mask etch and a substrate etch, so that successive iterations give life to reduction in the mask area and exposure of further areas of substrate.

Claims

1. A method of forming an optical confining structure, said method comprising producing or modifying a three dimensional surface profile on a substrate comprising the steps of:

(i) forming a mask of resist on the substrate such that some area of the substrate is protected by the mask and some area is exposed;

(ii) forming the resist into a dome;

(iii) subjecting the substrate and the mask to a plurality of iterations;

wherein each iteration comprises at least one resist etch and at least one substrate etch, the resist etch being carried out using a suitable resist etchant, which modifies the shape of the mask and hence the area of substrate exposed, and the substrate etch being carried out using a suitable substrate etchant from which the mask affords protection of the substrate, and which removes material from the areas of substrate which are exposed, the resist etch and the substrate etch being substantially asynchronous, so that substantially perpendicular straight edges are formed in the substrate.

2. The method of claim 1 an optical concentrator is formed in the substrate.

3. The method of claim 1 or 2 wherein the substrate comprises a semiconductor material.

4. The method of claim 3 where the substrate comprises InSb.

5. The method of claim 4 wherein the substrate etchant comprises a CH₄/H₂ plasma.

6. The method of claim 5 where the resist etchant comprises an oxygen plasma.

7. The method of claim 6 where a Winston cone emitter is formed in InSb heterostructure material.