Method for creating asymmetrical wafer

• US 9,390,906 B1
• Filed: 11/06/2013
• Issued: 07/12/2016
• Est. Priority Date: 06/01/2007
• Status: Expired due to Fees

• Current Assignee: Rubicon Technology, Inc.
• Original Assignee: Rubicon Technology, Inc.
• Inventors: Matthews, Michael W., Phatak, Sunil B.
• Primary Examiner(s): O'Hern, Brent
• Application Number:
  US14/073,602
• Time in Patent Office: 979 Days
• Field of Search: 257/49, 356/614
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02013 Grinding, lapping
• CPC Class Codes: H01L 21/02021 Edge treatment, chamfering
• CPC Class Codes: H01L 21/02024 Mirror polishing
• CPC Class Codes: H01L 21/02035 Shaping
• CPC Class Codes: H01L 2223/54426 for alignment
• CPC Class Codes: H01L 2223/54493 Peripheral marks on wafers, e.g. orientation flats, notches, lot number
• CPC Class Codes: H01L 23/544 Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps test patterns for characterising or monitoring manufacturing processes H01L22/00
• CPC Class Codes: H01L 29/0657 characterised by the shape of the body
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: Y10T 428/21 Circular sheet or circular blank
• CPC Class Codes: Y10T 428/219 Edge structure

Abstract

The present invention consists of a method for imparting asymmetry to a truncated annular wafer by either rounding one corner of the orientation flat, or rounding one corner of a notch. This novel method of rounding corners impart a visual and/or tactile asymmetry which can be utilized by a person in order to differentiate between the two different sides of the wafer. This inventive wafer design and method for making an asymmetric wafer is especially useful in the field of semiconductor technology and may be used on sapphire crystal wafers or any other class of wafer.

Claims

1. A method of making a plurality of wafers, comprising the steps of:

determining crystalline orientation of a substantially cylindrical crystal ingot;

shaping at least one orientation flat upon said substantially cylindrical-crystal ingot;

rounding at least one corner of said orientation flat to create a visual asymmetry to identify the determined crystalline orientation; and

slicing said substantially cylindrical crystal ingot into a plurality of wafers, each of the plurality of wafers having at least one rounded corner.

2. The method in claim 1, further comprising:

growing the substantially cylindrical crystal ingot.

3. The method in claim 2, further comprising the steps of:

grinding at least one surface and edge of each of said plurality of wafers; and

polishing and cleaning said plurality of wafers.

4. The method of claim 1, wherein said step of rounding at least one corner of said orientation flat further comprises rounding two corners of said orientation flat to differing radii to be visually asymmetric with respect to one another.

5. The method of claim 1, further comprising:

grinding at least one truncated flat upon said substantially cylindrical crystal ingot; and

grinding a secondary truncated flat upon said substantially cylindrical crystal ingot.

6. The method of claim 5, further comprising rounding at least one corner of the secondary truncated flat that is visually asymmetric to an opposing corner.

7. A method of making at least one substantially circular wafer, comprising the steps of:

determining crystalline orientation of a substantially cylindrical crystal ingot;

shaping at least one notch upon said substantially cylindrical crystal ingot; and

rounding two corners of said at least one notch to differing radii in order to be visually asymmetric to each other.

8. The method of claim 7, further comprising the steps of:

growing the substantially cylindrical crystal ingot; and

slicing said substantially cylindrical crystal ingot into a plurality of substantially circular wafers.

9. The method in claim 8, wherein said method of making a substantially circular wafer further comprises the steps of:

grinding at least one surface and edge of each of said plurality of substantially circular wafers; and

polishing and cleaning each of said plurality of substantially circular wafers.

10. The method of claim 7, wherein said step of shaping at least one notch upon said substantially cylindrical crystal ingot further comprises shaping a secondary notch upon said substantially cylindrical crystal ingot.

11. The method of claim 10, further comprising rounding at least one corner of the secondary notch in order to create visual asymmetry with respect to opposing corner of the secondary notch.