Optical alignment methods for forming LEDs having a rough surface
First Claim
1. A method of aligning a wafer when lithographically fabricating a light-emitting diode (LED), comprising:
- forming on the wafer at least one roughened alignment mark having a root-mean-square (RMS) surface roughness σ
S;
imaging the at least one roughened wafer alignment mark with alignment light having a wavelength λ
A that is in the range from about 2σ
S to about 8σ
S; and
comparing the detected image to an alignment reference to establish wafer alignment, wherein the alignment reference includes a reticle alignment mark.
2 Assignments
0 Petitions
Accused Products
Abstract
A method of aligning a wafer when lithographically fabricating a light-emitting diode (LED). The method includes forming on the wafer at least one roughened alignment mark having a root-mean-square (RMS) surface roughness σS. The roughened alignment mark is formed as a consequence of forming a plasma etch to roughen a LED surface on which the wafer alignment mark resides. The method also includes imaging the at least one roughened wafer alignment mark with alignment light having a wavelength λA that is in the range from about 2σS to about 8σS. The method also includes comparing the detected image to an alignment reference to establish wafer alignment. Once wafer alignment is established, p-contacts and n-contacts can be formed on the LED upper surface in their proper locations.
-
Citations
19 Claims
-
1. A method of aligning a wafer when lithographically fabricating a light-emitting diode (LED), comprising:
-
forming on the wafer at least one roughened alignment mark having a root-mean-square (RMS) surface roughness σ
S;imaging the at least one roughened wafer alignment mark with alignment light having a wavelength λ
A that is in the range from about 2σ
S to about 8σ
S; andcomparing the detected image to an alignment reference to establish wafer alignment, wherein the alignment reference includes a reticle alignment mark. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of performing wafer alignment when lithographically fabricating a light-emitting diode (LED), comprising:
-
forming at least one wafer alignment mark on the wafer; forming a rough wafer surface on or above the wafer alignment mark, the rough surface having a root-mean-square (RMS) surface roughness σ
S, wherein σ
S is within one of the following ranges, where n is a refractive index of a layer on which the rough surface is formed;i) from about 2λ
LED to about 8λ
LED;ii) from about (0.5)λ
ED/n to λ
ED/n;
oriii) from about λ
LED/n to λ
LED;illuminating the at least one wafer alignment mark with alignment light having a wavelength λ
A that is in the range from about 2σ
S to about 8σ
S;forming and detecting an image of the at least one wafer alignment mark with alignment light reflected from the at least one wafer alignment mark; and comparing the detected image to an alignment reference to establish wafer alignment. - View Dependent Claims (9, 10, 11, 12, 13, 14)
-
-
15. A method of forming at least one electrical contact on a light-emitting diode (LED) having an associated LED wavelength λ
-
LED and a LED structure, comprising;
forming wafer alignment marks on an upper surface of the LED structure; roughening the LED structure upper surface including the wafer alignment marks, thereby forming roughened wafer alignment marks, with the upper surface and roughened wafer alignment marks having a surface roughness σ
S;imaging the at least one roughened wafer alignment mark with alignment light having a wavelength λ
A that is in one of a) in the range from about 2σ
S to about 8σ
S, b) in the range from about 1 μ
m to about 2 μ
m, and or c) in the range from about 2λ
LED to about 8λ
LED;comparing the detected image to an alignment reference to establish wafer alignment, wherein the alignment reference includes a reticle alignment mark; and forming the at least one electrical contact on the LED structure upper surface. - View Dependent Claims (16, 17, 18, 19)
-
LED and a LED structure, comprising;
Specification