Joined wafer, fabrication method thereof, and fabrication method of semiconductor devices

• US 8,048,768 B2
• Filed: 07/01/2009
• Issued: 11/01/2011
• Est. Priority Date: 07/09/2008
• Status: Expired due to Fees

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Inventors: Yamada, Shigeru
• Primary Examiner(s): SARKAR, ASOK K
• Application Number:
  US12/458,149
• Publication Number:
  US 20100009491A1
• Time in Patent Office: 853 Days
• Field of Search: 156/273.3, 257/E21.122, 257/E21.567, 438/68, 438/455, 438/456, 438/460, 438/462
• US Class Current: 438/455
• CPC Class Codes: B32B 2038/0064 Smoothing, polishing, making a glossy surface
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2309/105 Thickness
• CPC Class Codes: B32B 2310/0806 using electromagnetic radiation
• CPC Class Codes: B32B 2315/08 Glass
• CPC Class Codes: B32B 2457/14 Semiconductor wafers
• CPC Class Codes: B32B 37/1292 selectively, e.g. in stripes, in patterns B32B37/0076 takes precedence

Abstract

A method of fabricating a joined wafer has an exposure process which comprises a device formed-area exposure process of exposing by a stepper such that parts of the photosensitive adhesive layer formed over a surface of the transparent wafer or the device formed wafer are removed, the parts corresponding to the device formed areas when the transparent wafer and the device formed wafer are stuck together; and a wafer periphery exposure process of exposing such that a portion of the photosensitive adhesive layer over the periphery of the transparent wafer is left.

Claims

1. A method of fabricating a joined wafer, which comprises at least:

a wafer preparing step of preparing a transparent wafer and a device formed wafer having device formed areas in its surface;

an adhesive layer forming step of forming a negative-type photosensitive adhesive layer over a surface of said transparent wafer or said device formed wafer;

an adhesive layer exposure step of exposing at least a portion of the photosensitive adhesive layer formed over said transparent wafer or said device formed wafer;

an adhesive layer developing step of developing the photosensitive adhesive layer formed over said transparent wafer or said device formed wafer to remove part thereof; and

a wafer sticking step of sticking said transparent wafer and said device formed wafer together with the photosensitive adhesive layer left on said transparent wafer or said device formed wafer so as to be a joined wafer,

wherein said adhesive layer exposure step comprises;

a device formed-area exposure step of exposing by a stepper such that parts of the photosensitive adhesive layer formed over said transparent wafer or said device formed wafer are removed, said parts corresponding to said device formed areas when said transparent wafer and said device formed wafer are stuck together; and

a wafer periphery exposure step of exposing such that a portion of the photosensitive adhesive layer over the periphery of said transparent wafer or said device formed wafer is left.

2. A method of fabricating a joined wafer according to claim 1, wherein in said adhesive layer exposure step, exposure is performed such that a remaining width of a portion of the photosensitive adhesive layer over the periphery of said transparent wafer is greater than a remaining width of a portion of the photosensitive adhesive layer corresponding to areas between adjacent ones of said device formed areas.

3. A method of fabricating a joined wafer according to claim 2, wherein said remaining width of a portion of the photosensitive adhesive layer over the periphery of said transparent wafer is twice, or greater than twice, said remaining width of a portion of the photosensitive adhesive layer corresponding to areas between adjacent ones of said device formed areas.

4. A method of fabricating a joined wafer according to claim 3, wherein said remaining width of a portion of the photosensitive adhesive layer corresponding to areas between adjacent ones of said device formed areas is 0.5 mm or greater, and said remaining width of a portion of the photosensitive adhesive layer over the periphery of said transparent wafer is 1.0 mm or greater.

5. A method of fabricating a joined wafer according to claim 1, wherein in said adhesive layer forming step, said photosensitive adhesive layer is formed over a surface of said transparent wafer.