COLOR FILTER ARRAY ALIGNMENT MARK FORMATION IN BACKSIDE ILLUMINATED IMAGE SENSORS
First Claim
1. A method of forming color filter array alignment marks in an image sensor wafer, the image sensor wafer being utilized to form a plurality of image sensors each having a pixel array configured for backside illumination, the image sensor wafer comprising at least a substrate and a sensor layer, the method comprising the steps of:
- forming color filter array alignment mark openings in the sensor layer; and
forming an epitaxial layer on a frontside surface of the sensor layer;
wherein the epitaxial layer comprises polysilicon color filter array alignment marks formed in locations corresponding to respective ones of the color filter array alignment mark openings in the sensor layer.
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Abstract
A backside illuminated image sensor includes a sensor layer comprising photosensitive elements of the pixel array, an epitaxial layer formed on a frontside surface of the sensor layer, and a color filter array formed on a backside surface of the sensor layer. The epitaxial layer comprises polysilicon color filter array alignment marks formed in locations corresponding to respective color filter array alignment mark openings in the frontside surface of the sensor layer. The color filter array is aligned to the color filter array alignment marks of the epitaxial layer. The image sensor may be implemented in a digital camera or other type of digital imaging device.
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Citations
20 Claims
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1. A method of forming color filter array alignment marks in an image sensor wafer, the image sensor wafer being utilized to form a plurality of image sensors each having a pixel array configured for backside illumination, the image sensor wafer comprising at least a substrate and a sensor layer, the method comprising the steps of:
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forming color filter array alignment mark openings in the sensor layer; and forming an epitaxial layer on a frontside surface of the sensor layer; wherein the epitaxial layer comprises polysilicon color filter array alignment marks formed in locations corresponding to respective ones of the color filter array alignment mark openings in the sensor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An image sensor having a pixel array configured for backside illumination, comprising:
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a sensor layer comprising a plurality of photosensitive elements of the pixel array; an epitaxial layer formed on a frontside surface of the sensor layer, the epitaxial layer comprising polysilicon color filter array alignment marks formed in locations corresponding to respective color filter array alignment mark openings in the frontside surface of the sensor layer; and a color filter array formed on a backside surface of the sensor layer; wherein the color filter array is aligned to the color filter array alignment marks of the epitaxial layer. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A digital imaging device comprising:
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an image sensor having a pixel array configured for backside illumination; and one or more processing elements configured to process outputs of the image sensor to generate a digital image; wherein said image sensor comprises; a sensor layer comprising a plurality of photosensitive elements of the pixel array; an epitaxial layer formed on a frontside surface of the sensor layer, the epitaxial layer comprising polysilicon color filter array alignment marks formed in locations corresponding to respective color filter array alignment mark openings in the frontside surface of the sensor layer; and a color filter array formed on a backside surface of the sensor layer; wherein the color filter array is aligned to the color filter array alignment marks of the epitaxial layer. - View Dependent Claims (20)
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Specification