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US 5,227,313 AGranted
Process for making backside illuminated image sensors
AssigneeEastman Kodak Company
InventorsRonald M. Gluck, Edmund K. Banghart, Madhav Mehra
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Abstract
A process for making a backside illuminated image sensor fabricated upon a thinned silicon layer bonded to a quartz wafer is described. A borosilicate glass (BSG) layer interposed between the thinned silicon device layer and quartz support serves as a doping source for the back-surface accumulating electrostatic potential and serves to minimize stress associated with the thermal expansion differences associated with quartz and silicon.
Claims7
A process for making backside illuminated image sensors comprising the steps of:
- (a) forming a doped etch stop layer on a silicon wafer;
- (b) forming a device layer on the etch stop layer;
- (c) forming an oxide layer having a controlled thickness on the device layer;
- (d) forming a borosilicate glass layer on one side of a quartz support wafer;
- (e) forming a silicon nitride layer on the other side of the quartz support wafer;
- (f) bonding the borosilicate glass surface of the support wafer to the oxide layer on the device layer of the silicon wafer, forming a composite wafer;
- (g) etching the bonded composite wafer up to the device layer;
- (h) forming devices including bond pads in the device layer;
- (i) etching the silicon nitride layer from the quartz support wafer to eliminate optical absorption of ultraviolet radiation by the silicon nitride layer;
- and
- (j) etching the devices to uncover the bond pads.
8 more elements
Dependencies are inferred from the claim text.