Method and apparatus for maintaining parallelism of layers and/or achieving desired thicknesses of layers during the electrochemical fabrication of structures

Patent metadata

Field	Value
Publication number	US-9714473-B2
Application number	US-201414191061-A
Country	US
Kind code	B2
Filing date	Feb 26, 2014
Priority date	Dec 31, 2003
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

Some embodiments of the present invention provide processes and apparatus for electrochemically fabricating multilayer structures (e.g. mesoscale or microscale structures) with improved endpoint detection and parallelism maintenance for materials (e.g. layers) that are planarized during the electrochemical fabrication process. Some methods involve the use of a fixture during planarization that ensures that planarized planes of material are parallel to other deposited planes within a given tolerance. Some methods involve the use of an endpoint detection fixture that ensures precise heights of deposited materials relative to an initial surface of a substrate, relative to a first deposited layer, or relative to some other layer formed during the fabrication process. In some embodiments planarization may occur via lapping while other embodiments may use a diamond fly cutting machine.

First claim

We claim:

1. In a batch fabrication process for forming a plurality of multi-layer three-dimensional structures including: (a) forming and adhering a first multi-material layer to a substrate; (b) forming and adhering one or more successive multi-material layers to the first multi-material layer or to a previously formed successive multi-material layer, wherein each multi-material layer comprises planarized patterns of at least one deposited structural material and at least one deposited sacrificial material, and (c) after formation of the plurality of multi-material layers separating the deposited sacrificial material from the deposited structural material to reveal the plurality of multi-layer three-dimensional structures formed from the at least one deposited structural material, wherein the improvement comprises:
(i) during formation of a given multi-material layer, and after deposition of the at least one deposited structural material and the at least one deposited sacrificial material for the given layer and with one or more measurement pads existing on a surface of the substrate or on a surface of a previously formed multi-material layer, mounting the substrate to a fixture in a fly cutting machine;
(ii) while the substrate is mounted to the fixture, subjecting the at least one deposited structural material and at least one deposited sacrificial material, but not the one or more measurement pads, to a rotating cutting tool to planarize a surface of the at least one deposited structural material and at least one deposited sacrificial material for the given multi-material layer and to bring the height of the at least one deposited structural material and at least one deposited sacrificial material for the given multi-material layer to a reduced level;
(iii) after the planarization operation, locating a measurement device in contact with the one or more measurement pads and locating the measurement device in contact with one or more points on at least one of the at least one deposited structural material and at least one deposited sacrificial material for the given layer that were subject to the planarization operation;
(iv) extracting data from the measurement device concerning a measured height of at least one point relative to a reference point or plane that is based at least in part on the one or more measurement pads;
(v) comparing the measured height to a target structure height for the given layer; and
(vi) if the measured height and the target structure height are not within a desired tolerance, repeating operations (ii)-(v) until the measured height and target structure height are with the desired tolerance.

2. The process of claim 1 wherein the patterns of the at least one deposited structural material and the at least one deposited sacrificial material for the given multi-material layer are formed using a process comprising a selective deposition of a first material and a blanket deposition of a second material, wherein the first material comprises a selected one of the at least one deposited structural material while the second material comprises another of the at least one deposited structural material and the at least one deposited sacrificial material.

3. The process of claim 1 wherein the patterns of the at least one deposited structural material and the at least one deposited sacrificial material for the given multi-material layer are formed using a process comprising a selective deposition of a first material, a blanket deposition of a second material and wherein at least one of the first or second materials is deposited via an electroplating operation, and wherein the first material comprises a selected one of the at least one deposited structural material while the second material comprises another of the at least one deposited structural material and the at least one deposited sacrificial material.

4. The process of claim 1 wherein a lapping operation is used to remove a portion of the at least one deposited structural material and the at least one deposited sacrificial material of the given layer prior to mounting the substrate in the fly cutting machine.

5. The process of claim 1 , wherein the planarization operation includes a diamond machining operation.

6. The process of claim 1 wherein the substrate includes a sacrificial layer such that the plurality of structures may be released from the substrate.

7. In a batch fabrication process for forming a plurality of multi-layer three-dimensional structures including: (a) forming and adhering a first multi-material layer to a substrate; (b) forming and adhering one or more successive multi-material layers to the first multi-material layer or to a previously formed successive multi-material layer, wherein each multi-material layer comprises planarized patterns of at least one deposited structural material and at least one deposited sacrificial material, and (c) after formation of the plurality of multi-material layers separating the deposited sacrificial material from the deposited structural material to reveal the plurality of multi-layer three-dimensional structures formed from the at least one deposited structural material, wherein the improvement comprises:
(i) during formation of a given multi-material layer, and after deposition of the at least one deposited structural material and the at least one deposited sacrificial material for the given layer and with one or more measurement pads existing on the substrate or a previously formed multi-material layer, subjecting the at least one deposited structural material and the at least one deposited sacrificial material of the given multi-material layer to a planarization operation without subjecting the one or more measurement pads to planarization;
(ii) after the planarization operation, locating at least one measurement probe in contact with the one or more measurement pads and locating the at least one measurement probe in contact with one or more points on at least one of the at least one deposited structural material and the at least one deposited sacrificial material for the given layer that were subject to the planarization operation;
(iii) extracting data from the measurement probe concerning a measured height of the at least one deposited structural material and the at least one deposited sacrificial material for the given layer relative to a reference point or plane based on the at least one or more measurement pads;
(iv) comparing the measured height to a target structure height for the given layer; and
(v) if the measured height and target structure height are not within a desired tolerance, repeating operations (i)-(iv) until the measured height and target height or layer thickness are within the desired tolerance.

8. The process of claim 5 wherein the one or more measurement pads comprise at least three measurements pads.

9. The process of claim 5 wherein the measurement probe comprises at least three fixed length standoffs and at least one moveable probe.

10. The process of claim 9 wherein the at least one moveable probe comprises at least three moveable probes.

11. The process of claim 9 wherein the at least one moveable probe comprises at least four moveable probes.

12. The process of claim 9 wherein the one or more measurement pads comprise at least three measurement pads, and wherein the locating of step (d) comprises locating the at least three fixed length standoffs on the at least three measurement pads and locating the at least one moveable probe in contact with the one or more points on the at least two deposited materials that were subject to the planarization operation.

13. The process of claim 9 wherein th

Assignees

• Microfabrica Inc

Inventors

• Frodis Uri
• Cohen Adam L
• Lockard Michael S

Classifications

• H10P14/47

  Electrolytic deposition, i.e. electroplating; Electroless plating · CPC title

• H10W20/063

  by forming conductive members before forming protective insulating material · CPC title

• H10P52/00 Primary

  Grinding, lapping or polishing of wafers, substrates or parts of devices · CPC title

• C25D5/022

  using masking means · CPC title

• B81C1/00492

  Processes for surface micromachining not provided for in groups B81C1/0046 - B81C1/00484 · CPC title