Lithium tantalate substrate and method of manufacturing same

• US 20040255842A1
• Filed: 04/06/2004
• Published: 12/23/2004
• Est. Priority Date: 04/08/2003
• Status: Abandoned Application

• Current Assignee: Sumimoto Metal Mining Company Limited
• Original Assignee: Sumimoto Metal Mining Company Limited
• Inventors: Kajigaya, Tomio, Kakuta, Takashi
• Application Number:
  US10/819,472
• Publication Number:
  US 20040255842A1
• Time in Patent Office: Days
• US Class Current: 117/2
• CPC Class Codes: C30B 15/00 Single-crystal growth by pulling from a melt, e.g. Czochralski method under a protective fluid C30B27/00
• CPC Class Codes: C30B 29/30 Niobates; Vanadates; Tantalates
• CPC Class Codes: C30B 33/00 After-treatment of single crystals or homogeneous polycrystalline material with defined structure C30B31/00 takes precedence
• CPC Class Codes: C30B 33/02 Heat treatment C30B33/04, C30B33/06 take precedence
• CPC Class Codes: G02F 1/3551 Crystals
• CPC Class Codes: G02F 2202/20 LiNbO3, LiTaO3

Abstract

In a process for manufacturing a LT substrate from a LT crystal, after growing the crystal, a LT substrate in ingot form is imbedded in carbon power, or is place in a carbon vessel, and heat treated is conducted at a maintained temperature of between 650° C. and 1650° C. for at least 4 hours, whereby in a lithium tantalate (LT) substrate, sparks are prevented from being generated by the charge up of an electric charge on the substrate surface, and thereby destruction of a comb pattern formed on the substrate surface and breaks or the like in the LT substrate are prevented.

Claims

1. A lithium tantalate substrate having a thermal history of heat treatment wherein lithium tantalate in ingot form is maintained at a temperature of between 650°

C. and 1650°

C., while embedded in a carbon powder, or in a carbon vessel.

5. A lithium tantalate substrate according to any one of claim 1 through claim 4, wherein the heat treatment lasts 4 hours or longer.

6. A lithium tantalate substrate which is blackened by the heat treatment according to any one of claim 1 through claim 5.

2. A lithium tantalate substrate having a thermal history of heat treatment wherein lithium tantalate in ingot form is maintained at a temperature of between 650°

C. and 1400°

C., while embedded in a Si powder, or in a Si vessel.

3. A lithium tantalate substrate having a thermal history of heat treatment wherein lithium tantalite in wafer form is maintained at a temperature of between 350°

C. and 600°

C., while embedded in a metal powder selected from a group consisting of Ca, Al, Ti, and Si.

4. A lithium tantalate substrate having a thermal history of heat treatment wherein lithium tantalite in wafer form is maintained at a temperature of 350°

C. or higher and below the melting point of Zn, while embedded in a Zn powder.

7. A method of manufacturing a lithium tantalate substrate using a lithium tantalate crystal grown using the Czochralski method, comprising the step of heat treating the lithium tantalate crystal in ingot form, which is embedded in carbon powder or in a carbon vessel, at a maintained temperature of between 650°

C. and 1650°

C.

8. A method of manufacturing a lithium tantalate substrate using a lithium tantalate crystal grown using the Czochralski method, comprising the step of heat treating the lithium tantalate crystal in ingot form, which is embedded in Si powder or in a Si vessel, at a maintained temperature of between 650°

C. and 1400°

C.

9. A method of manufacturing a lithium tantalate substrate using a lithium tantalate crystal grown using the Czochralski method, comprising the step of heat treating the lithium tantalate crystal in wafer form, which is embedded in a metal powder selected from a group consisting of Ca, Al, Ti, and Si, at a maintained temperature of between 350°

C. and 600°

C.

10. A method of manufacturing a lithium tantalate substrate using a lithium tantalate crystal grown using the Czochralski method, comprising the step of heat treating the lithium tantalate crystal in wafer form, which is embedded in a Zn powder, at a maintained temperature of 350°

C. or higher and below the melting point of Zn.

11. A method of manufacturing a lithium tantalate substrate according to any one of claim 7 through claim 10, wherein the heat treatment lasts 4 hours or longer.