Electrochemical fabrication process for forming multilayer multimaterial microprobe structures

• US 9,244,101 B2
• Filed: 04/28/2009
• Issued: 01/26/2016
• Est. Priority Date: 02/04/2003
• Status: Expired due to Fees

• Current Assignee: University of Southern California
• Original Assignee: University of Southern California
• Inventors: Cohen, Adam L., Kumar, Ananda H., Lockard, Michael S., Smalley, Dennis R.
• Primary Examiner(s): Wong, Edna
• Application Number:
  US12/431,680
• Publication Number:
  US 20090320990A1
• Time in Patent Office: 2,464 Days
• Field of Search: 205/118, 205/122, 205/170, 427/256, 427/258
• US Class Current: 1/1
• CPC Class Codes: C23C 18/1605 by masking
• CPC Class Codes: C23C 18/1651 Two or more layers only obtained by electroless plating
• CPC Class Codes: C25D 1/003 3D structures, e.g. superposed patterned layers
• CPC Class Codes: C25D 5/02 Electroplating of selected surface areas
• CPC Class Codes: C25D 5/10 Electroplating with more than one layer of the same or of different metals for bearings C25D7/10
• CPC Class Codes: G01R 1/06716 Elastic
• CPC Class Codes: G01R 1/06744 Microprobes, i.e. having dimensions as IC details
• CPC Class Codes: G01R 1/06755 Material aspects
• CPC Class Codes: G01R 3/00 Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments , e.g. of probe tips
• CPC Class Codes: H01L 21/4853 Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps

Abstract

Some embodiments of the invention are directed to the electrochemical fabrication of microprobes which are formed from a core material and a material that partially coats the surface of the probe. Other embodiments are directed to the electrochemical fabrication of microprobes which are formed from a core material and a material that completely coats the surface of each layer from which the probe is formed including interlayer regions. These first two groups of embodiments incorporate both the core material and the coating material during the formation of each layer. Still other embodiments are directed to the electrochemical fabrication of microprobe arrays that are partially encapsulated by a dielectric material during a post layer formation coating process. In even further embodiments, the electrochemical fabrication of microprobes from two or more materials may occur by incorporating a coating material around each layer of the structure without locating the coating material in inter-layer regions.

Claims

1. A fabrication process for forming a multi-material, multi-layer three-dimensional structure, comprising:

(a) providing an initial multi-material layer on a sacrificial material on a substrate;

(b) forming and adhering a first successive multi-material layer to the initial multi-material layer and forming any additional successive multi-material layer or layers on and adhered to the first successive multi-material layer or to a subsequently formed successive multi-material layer to build up a three-dimensional structure from a plurality of adhered multi-material layers,

wherein each multi-material layer comprises a first structural material and a sacrificial material,

wherein at least one of the adhered multi-material layers further comprises a second structural material, and wherein the three-dimensional structure is formed from the first structural material and the second structural material;

(c) after formation of the plurality of adhered multi-material layers, separating the sacrificial material forming part of each of the plurality of adhered multi-material layers to reveal the three-dimensional structure comprising the first structural material and the second structural material;

wherein formation of the at least one multi-material layer of the plurality of adhered multi-material layers comprises formation of a first of at least two consecutive multi-material layers and comprises;

1) selectively depositing the sacrificial material into a pattern of photoresist;

2) removing the photoresist to yield at least one void that is surrounded on the side by the deposited sacrifical material;

3) depositing the first structural material into the void to a thickness less than the thickness of the first of the at least two consecutive layers such that a portion of the at least one void remains that is surround on the bottom and sides by the deposited first structural material;

4) depositing the second structural material to occupy the portion of the at least one void that remains after depositing the first structural material;

5) planarizing the first structural material, the second structural material, and the sacrificial material to set a boundary level for the first of the at least two consecutive layers;

wherein the second structural material is different from the first structural material; and

wherein the formation of an additional multi-material layer of the at least two consecutive multi-material layers, which is different from the first of the at least two consecutive multi-material layers, comprises;

1) depositing the sacrificial material and the first structural material for the additional multi-material layer onto a previously formed multi-material layer of the at least two consecutive multi-material layers and then planarizing the sacrificial material and the first structural material to set a boundary level for the additional multi-material layer of the at least two consecutive multi-material layers such that the second structural material deposited to occupy the portion of the at least one void is completely isolated from sacrificial material that is separated in step (c), and

wherein the sacrificial material and first and second structural materials are metals and at least one of the depositing steps comprises an electrochemical deposition step.

2. The process of claim 1 wherein the second structural material is the same material as the sacrificial material.

3. The process of claim 1 wherein the first structural material, the second structural material, and the sacrificial material on the first of the at least two consecutive multi-material layers are all different materials.

4. The process of claim 1 wherein the first structural material forming part of at least two of the plurality of multi-materials layers are different materials.

5. The process of claim 1 wherein the depositing of each of the first and second structural materials forming the plurality of multi-material layers occurs by electroplating.