Optical alignment systems for forming LEDs having a rough surface
First Claim
1. An alignment system for aligning a wafer when lithographically fabricating on the wafer a light-emitting diode (LED) having a wavelength λ
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LED, comprising;
the wafer, with the wafer having at least one wafer alignment mark;
a rough surface formed on or above the wafer alignment mark and on a layer having a refractive index n, the rough surface having a root-mean-square (RMS) surface roughness σ
S that is within one of the following ranges;
i) from about 2λ
LED to about 8λ
LED;
ii) from about (0.5)λ
LED/n to λ
LED/n;
oriii) from about λ
LED/n to λ
LED;
a light source that illuminates 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;
a lens configured to form an image of the at least one wafer alignment mark at the alignment light wavelength λ
A;
an image sensor configured to detect the image and form therefrom a digital alignment mark image; and
an image processing unit electrically connected to the image sensor and configured to receive and compare the digital alignment mark image to an alignment reference to establish a wafer alignment with respect to the alignment reference.
1 Assignment
0 Petitions
Accused Products
Abstract
An alignment system for aligning a wafer when lithographically fabricating LEDs having an LED wavelength λLED is disclosed. The system includes the wafer. The wafer has a roughened alignment mark with a root-mean-square (RMS) surface roughness σS. The system has a lens configured to superimpose an image of the reticle alignment mark with an image of the roughened alignment mark. The roughened alignment marked image is formed with alignment light having a wavelength λA that is in the range from about 2σS to about 8σS. An image sensor detects the superimposed image. An image processing unit processes the detected superimposed image to measure an alignment offset between the wafer and the reticle.
23 Citations
20 Claims
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1. An alignment system for aligning a wafer when lithographically fabricating on the wafer a light-emitting diode (LED) having a wavelength λ
-
LED, comprising;
the wafer, with the wafer having at least one wafer alignment mark; a rough surface formed on or above the wafer alignment mark and on a layer having a refractive index n, the rough surface having a root-mean-square (RMS) surface roughness σ
S that is within one of the following ranges;i) from about 2λ
LED to about 8λ
LED;ii) from about (0.5)λ
LED/n to λ
LED/n;
oriii) from about λ
LED/n to λ
LED;a light source that illuminates 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;a lens configured to form an image of the at least one wafer alignment mark at the alignment light wavelength λ
A;an image sensor configured to detect the image and form therefrom a digital alignment mark image; and an image processing unit electrically connected to the image sensor and configured to receive and compare the digital alignment mark image to an alignment reference to establish a wafer alignment with respect to the alignment reference. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9, 10)
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LED, comprising;
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6. The alignment system of 1, further comprising the image processing unit configured to perform enhanced global alignment using multiple wafer alignment marks.
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11. An alignment system for aligning a wafer to a reticle having a reticle alignment mark when lithographically fabricating, with a lithography system having a projection lens, a light-emitting diode (LED) having an LED wavelength λ
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LED, the system comprising;
the wafer, wherein the wafer includes a roughened alignment mark having a root-mean-square (RMS) surface roughness σ
S;a lens configured to superimpose an image of the reticle alignment mark with an image of the roughened alignment mark as formed with alignment light having a wavelength λ
A that is in the range from about 2σ
S to about 8σ
S;an image sensor configured to detect the superimposed image and form therefrom digital superimposed image representative of the superimposed image; and an image processing unit electrically connected to the image sensor and adapted to receive the digital superimposed image and perform pattern recognition of the digital superimposed image to measure an alignment offset between the wafer and reticle. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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LED, the system comprising;
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18. An alignment system for aligning a wafer to a reticle having a reticle alignment mark when lithographically fabricating, with a lithography system with a projection lens, a light-emitting diode (LED) having an LED wavelength λ
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LED, the system comprising;
the wafer, wherein the wafer includes a roughened alignment mark having a root-mean-square (RMS) surface roughness σ
S;the projection lens, with projection lens configured to work in conjunction with a lens to form a superimposed image that includes;
i) an image of the roughened alignment mark formed with alignment light having a wavelength λ
A that is in the range from about 2σ
S to about 8σ
S, and ii) an image of the reticle alignment mark;an image sensor configured to detect the superimposed image and form therefrom digital superimposed image representative of the superimposed image; and an image processing unit electrically connected to the image sensor and adapted to receive the digital superimposed image and perform pattern recognition of the digital superimposed image to measure an alignment offset between the wafer and reticle. - View Dependent Claims (19, 20)
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LED, the system comprising;
Specification