Wafer production method

Patent metadata

Field	Value
Publication number	US-10774445-B2
Application number	US-201715397309-A
Country	US
Kind code	B2
Filing date	Jan 3, 2017
Priority date	Jan 7, 2016
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

A wafer production method for producing a wafer from a lithium tantalate ingot includes a step of irradiating, from an end face of a lithium tantalate ingot which is a 42-degree rotation Y cut ingot having an orientation flat formed in parallel to a Y axis, a laser beam of a wavelength having transparency to lithium tantalate with a focal point of the laser beam positioned in the inside of the ingot to form a modified layer in the inside of the ingot while the ingot is fed for processing, and a step of applying external force to the ingot to peel off a plate-shaped material from the ingot to produce a wafer. At the step of forming a modified layer, the ingot is relatively fed for processing in a direction parallel or perpendicular to the orientation flat.

First claim

What is claimed is:

1. A wafer production method for producing a wafer from a lithium tantalate ingot which is a 42-degree rotation Y cut ingot having an end face extending perpendicularly with respect to a center axis set with a rotational angle of 42 degrees with respect to a Y axis orthogonal to a crystal axis of a lithium tantalate and having an orientation flat formed in parallel to the Y axis, the method comprising:
a modified layer formation step of irradiating a laser beam of a wavelength having transparency to lithium tantalate, with a focal point of the laser beam positioned at a depth corresponding to a thickness of a wafer to be produced, from the end face of the lithium tantalate ingot, to form a modified layer within the lithium tantalate ingot while the lithium tantalate ingot is fed for processing relative to the laser beam in a direction parallel or perpendicular to the orientation flat;
applying ultrasonic vibrations to the lithium tantalate ingot; and
a wafer production step of applying, after the modified layer formation step is carried out, a rotational external force to the lithium tantalate ingot to peel off a layer of material from the lithium tantalate ingot to produce a wafer, wherein said rotational external force rotates the lithium tantalate ingot about the center axis.

2. The wafer production method according to claim 1 , further comprising a grinding step of grinding a peeling face of the produced wafer and a peeling face of the lithium tantalate ingot to flatten the peeling faces.

3. The wafer production method according to claim 1 , further comprising a fixing step of fixing, prior to the modified layer formation step, the lithium tantalate ingot to a holding table.

4. The wafer production method according to claim 3 , wherein said fixing step includes placing a bonding agent between the lithium tantalate ingot and the holding table.

5. The wafer production method according to claim 3 , further comprising an adjusting step of adjusting the focal point of the laser beam to a position within the lithium tantalate ingot that is a predetermined distance from the surface of the lithium tantalate ingot fixed to the holding table.

6. The wafer production method according to claim 1 , further comprising an alignment step of detecting a region of the lithium tantalate ingot to be irradiated by the laser beam and a height of a surface of the lithium tantalate ingot.

7. A wafer production method for producing a wafer from a lithium tantalate ingot which is a 42-degree rotation Y cut ingot having an end face extending perpendicularly with respect to a center axis set with a rotational angle of 42 degrees with respect to a Y axis orthogonal to a crystal axis of a lithium tantalate and having an orientation flat formed in parallel to the Y axis, the method comprising:
a modified layer formation step of irradiating a laser beam of a wavelength having transparency to lithium tantalate, with a focal point of the laser beam positioned at a depth corresponding to a thickness of a wafer to be produced, from the end face of the lithium tantalate ingot, to form a modified layer within the lithium tantalate ingot while the lithium tantalate ingot is fed for processing relative to the laser beam in a direction parallel or perpendicular to the orientation flat; and
a wafer production step of moving, after the modified layer formation step is carried out, a peeling unit arm into contact with the lithium tantalate ingot and applying a rotational external force to the lithium tantalate ingot using the peeling unit arm to peel off a layer of material from the lithium tantalate ingot to produce a wafer, wherein said peeling unit arm rotates the lithium tantalate ingot about the center axis.

8. The wafer production method according to claim 7 , further comprising a grinding step of grinding a peeling face of the produced wafer and a peeling face of the lithium tantalate ingot to flatten the peeling faces.

9. The wafer production method according to claim 7 , further comprising a fixing step of fixing, prior to the modified layer formation step, the lithium tantalate ingot to a holding table.

10. The wafer production method according to claim 9 , wherein said fixing step includes placing a bonding agent between the lithium tantalate ingot and the holding table.

11. The wafer production method according to claim 9 , further comprising an adjusting step of adjusting the focal point of the laser beam to a position within the lithium tantalate ingot that is a predetermined distance from the surface of the lithium tantalate ingot fixed to the holding table.

12. The wafer production method according to claim 7 , further comprising an alignment step of detecting a region of the lithium tantalate ingot to be irradiated by the laser beam and a height of a surface of the lithium tantalate ingot.

13. The wafer production method according to claim 7 , further comprising applying ultrasonic vibrations to the lithium tantalate ingot.

Assignees

• Disco Corp
• Disco Corproation

Inventors

• Hirata Kazuya

Classifications

• H10P34/42

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• H10W10/01

  Manufacture or treatment · CPC title

• H10P32/185

  Lithium-drift diffusion · CPC title

• H10P14/69393

  the material containing tantalum, e.g. Ta2O5 · CPC title

• H10P90/123

  by grinding or lapping · CPC title