IP Library Granted Patent US 7,241,699
Granted Patent B2
US 7,241,699 · App. 10/630,238 · Granted Jul 10, 2007

Wide bandgap semiconductor device construction

Assignee: Microsemi Corp.
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Quick Facts
Patent No.
US 7,241,699
App. No.
10/630,238
Granted
Jul 10, 2007
Kind
B2
Abstract

The invention includes methods for precisely and accurately etching layers of wide bandgap semiconductor material. According to one aspect of the invention, the method includes providing a multi-layer laminate including at least a first and second layer of wide bandgap semiconductor material, measuring a first conductance of the first layer of semiconductor material, partially etching the first layer of semiconductor material a first amount, measuring a second conductance of the first layer of semiconductor material etched the first amount, and utilizing the first and second measured conductance to determine a time required to etch the first layer of semiconductor material a second amount.

Claims (64)

1. A method for precisely etching a wide bandgap semiconductor device, the method comprising the steps of:

(a) providing a multi-layer laminate including at least a first and second layer of wide bandgap semiconductor material;

(b) isolating an area of the first layer of semiconductor material for locating a conductance measurement device;

(c) measuring a first conductance of the isolated area of the first layer of semiconductor material using the conductance measurement device;

(d) first etching a first amount of the first layer of semiconductor material;

(e) measuring a second conductance of the isolated area of the first layer of semiconductor material subsequent to etching the first amount of the first layer of semiconductor material; and

(f) utilizing the first and second measured conductance to determine a time required to etch a second amount of the first layer of semiconductor material.

2. The method of claim 1 the method comprising:

repeating steps (d) through (f) to determine an optimal time to etch the second amount of the first layer of semiconductor material to achieve a desired etch depth.

3. The method of claim 1 wherein the utilizing step includes:

determining a difference between the first measured conductance and the second measured conductance; and

calculating the time required to remove the second amount of the first layer of semiconductor material using the difference between the first measured conductance and the second measured conductance and a time required to complete the first etching step.

4. The method of claim 1 the method comprising:

repeating steps (d) through (f) to identify an optimum etch depth for the first layer of semiconductor material.

5. The method of claim 1 wherein the first layer of semiconductor material includes a first conductivity type and the second layer of semiconductor material includes a second conductivity type different from the first conductivity type.

6. The method of claim 1 wherein the device is a radio frequency power device.

7. The method of claim 1 wherein the device is a p-n junction.

8. The method of claim 1 wherein the device is a transistor.

9. The method of claim 1 wherein the device is a thyristor.

10. The method of claim 1 the method comprising:

subsequent to the utilizing step, second etching the first layer of semiconductor material for the determined amount of time to remove the second amount of the first layer of semiconductor material.

11. The method of claim 10 wherein the second etching step comprises:

etching at least a portion of the first layer of semiconductor material to a junction between the first and second layer of semiconductor material.

12. The method of claim 10 wherein the second etching step comprises:

removing at least a portion of the first layer of semiconductor material to achieve a predetermined thickness of the at least a portion of the first layer of semiconductor material.

13. A method for precisely etching a wide bandgap semiconductor device, the method comprising the steps of:

(a) providing a multi-layer laminate including at least a first and second layer of wide bandgap semiconductor material;

(b) measuring a first conductance of the first layer of semiconductor material;

(c) first etching the first layer of semiconductor material a first amount;

(d) measuring a second conductance of the first layer of semiconductor material etched the first amount; and

(e) repeating steps (c) and (d) to determine an optimal time to etch the first layer of semiconductor material a second amount.

14. The method of claim 13 the method comprising:

determining a difference between the first measured conductance and the second measured conductance; and

calculating the optimal time using the difference between the first measured conductance and the second measured conductance and a time required to complete the first etching step.

15. The method of claim 13 the method comprising:

repeating steps (c) and (d) to identify an optimum etch depth for the first layer of semiconductor material.

16. The method of claim 13 wherein the first layer of semiconductor material includes a first conductivity type and the second layer of semiconductor material includes a second conductivity type different from the first conductivity type.

17. The method of claim 13 wherein the device is a radio frequency power device.

18. The method of claim 13 wherein the device is a p-n junction.

19. The method of claim 13 wherein the device is a transistor.

20. The method of claim 13 wherein the device is a thyristor.

21. The method of claim 13 the method comprising:

subsequent to the providing step, isolating an area of the first layer of semiconductor material for locating a conductance measurement device.

22. The method of claim 21 wherein the step of measuring the first conductance comprises:

measuring the first conductance of the isolated area of the first layer of semiconductor material using the conductance measurement device.

23. The method of claim 13 the method comprising:

subsequent to the repeating step, second etching the first layer of semiconductor material for the determined optimal amount of time to remove the second amount of the first layer of semiconductor material.

24. The method of claim 23 wherein the second etching step comprises:

etching at least a portion of the first layer of semiconductor material to a junction between the first and second layer of semiconductor material.

25. The method of claim 23 wherein the second etching step comprises:

removing at least a portion of the first layer of semiconductor material to achieve a predetermined thickness of the at least a portion of the first layer of semiconductor material.

26. A method for use in semiconductor fabrication comprising:

establishing a mathematical correlation for determining an etch time for etching a material, the mathematical correlation reflecting a relationship between a conductance of a layer of said material and a thickness of said layer, wherein said layer conductance reduces with etching of said layer thickness;

using the mathematical correlation to determine an etch time for etching an amount of the material; and

using said determined etch time to produce a multi-layer laminate including at least a first and second layer of wide bandgap semiconductor material.

27. The method of claim 26 wherein an initial layer thickness remains unknown.

28. A method for use in semiconductor fabrication comprising:

establishing a mathematical correlation for determining an etch time for etching a material, the mathematical correlation reflecting a relationship between a conductance of a layer of said material and a thickness of said layer, wherein said layer conductance reduces with said layer thickness; and

using the mathematical correlation to determine an etch time for etching an amount of the material,

wherein said step of establishing comprises

(a) obtaining a first conductance measurement of a layer and a second conductance measurement of the layer, wherein the first conductance measurement of the layer is obtained before an etch of the layer and the second conductance measurement of the layer is obtained after the etch of the layer; and

(b) using the first conductance measurement of the layer and the second conductance measurement of the layer to determine the etch time for etching an additional amount of the layer of material.

29. The method of claim 28 comprising:

repeating steps (a) and (b) to achieve an optimum etch depth for the layer of material.

Assignments (7)
RELEASE OF SECURITY INTEREST Recorded Jan 19, 2016
From: BANK OF AMERICA, N.A.
To: MICROSEMI CORPORATION; MICROSEMI CORP.-ANALOG MIXED SIGNAL GROUP, A DELAWARE CORPORATION; MICROSEMI SOC CORP., A CALIFORNIA CORPORATION; MICROSEMI SEMICONDUCTOR (U.S.) INC., A DELAWARE CORPORATION; MICROSEMI FREQUENCY AND TIME CORPORATION, A DELAWARE CORPORATION; MICROSEMI COMMUNICATIONS, INC. (F/K/A VITESSE SEMICONDUCTOR CORPORATION), A DELAWARE CORPORATION; MICROSEMI CORP.-MEMORY AND STORAGE SOLUTIONS (F/K/A WHITE ELECTRONIC DESIGNS CORPORATION), AN INDIANA CORPORATION
Reel/Frame 037558/0711 →
NOTICE OF SUCCESSION OF AGENCY Recorded Apr 9, 2015
From: ROYAL BANK OF CANADA (AS SUCCESSOR TO MORGAN STANLEY & CO. LLC)
To: BANK OF AMERICA, N.A., AS SUCCESSOR AGENT
Reel/Frame 035657/0223 →
CONFIRMATORY LICENSE Recorded Oct 16, 2012
From: UNIVERSITY OF COLORADO
To: NAVY, SECRETARY OF THE UNITED STATES OF AMERICA
Reel/Frame 029217/0524 →
PATENT SECURITY AGREEMENT Recorded Feb 11, 2011
From: WHITE ELECTRONIC DESIGNS CORP.; ACTEL CORPORATION; MICROSEMI CORPORATION
To: MORGAN STANLEY & CO. INCORPORATED
Reel/Frame 025783/0613 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jun 14, 2007
From: ADVANCED POWER TECHNOLOGY COLORADO, INC.
To: MICROSEMI CORPORATION
Reel/Frame 019429/0902 →
CHANGE OF NAME Recorded Apr 15, 2005
From: POWERSICEL, INC.
To: ADVANCED POWER TECHNOLOGY COLORADO, INC.
Reel/Frame 016086/0911 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 8, 2003
From: VAN ZEGHBROECK, BART J.; PEREZ, IVAN; TORVIK, JOHN T.
To: POWERSICEL, INC.
Reel/Frame 014793/0812 →
Continuity (2)
Provisional Application 6039995700 · Jul 30, 2002
Related Publication 20040082191A1 · Apr 29, 2004