Method of making backside illuminated image sensors

• US 5,244,817 A
• Filed: 08/03/1992
• Issued: 09/14/1993
• Est. Priority Date: 08/03/1992
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Hawkins, Gilbert A., Gluck, Ronald M.
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): TRINH, MICHAEL MANH
• Application Number:
  US07/923,674
• Time in Patent Office: 407 Days
• Field of Search: 437/2, 437/4, 437/5, 437/974, 437/225, 437/53, 437/236, 148/DIG. 12, 148/DIG. 135
• US Class Current: 438/64
• CPC Class Codes: H01L 21/2007 Bonding of semiconductor wafers to insulating substrates or to semiconducting substrates using an intermediate insulating layer H01L21/2011 takes precedence; bonding of semiconductor wafers to semiconductor wafers for junction formation H01L21/187
• CPC Class Codes: H01L 27/1203 the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14687 Wafer level processing
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y10S 148/012 Bonding, e.g. electrostatic for strain gauges
• CPC Class Codes: Y10S 148/135 Removal of substrate
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

A method of making a backside illuminated image includes forming a device on the frontside of thin device layer provided on an oxide layer which is mounted on a sacrificial substrate and bonding the front side of the device layer to a permanent silicon support substrate. Thereafter, the oxide layer and sacrificial layer are removed by chemical etching to expose the backside of the thin device layer.

Claims

1. In a method of making an image sensor which will be backside illuminated, comprising the steps of:

(a) forming a first oxide layer on a thin epitaxial device layer grown on a first sacrificial silicon substrate;

(b) forming a boron containing region at the interface of the backside of the device layer and the first oxide layer which acts as a chemical etch stop;

(c) bonding a second oxide layer on a second sacrificial silicon substrate with the first oxide layer;

(d) removing the first sacrificial substrate by chemical etching to expose the front surface of the thin epitaxal device layer;

(e) after step (d) forming devices and bondpads in and on the front surface of the thin epitaxial device layer;

(f) bonding the thin device layer to a permanent silicon support substrate; and

(g) removing by chemical etching the second oxide layer and the second sacrificial silicon substrate.

2. The method of claim 1 wherein the thin device layer is bonded by an epitaxial layer to the support substrate.