Substrates for semiconductor devices

Patent metadata

Field	Value
Publication number	US-2016186362-A1
Application number	US-201314648256-A
Country	US
Kind code	A1
Filing date	Dec 4, 2013
Priority date	Dec 18, 2012
Publication date	Jun 30, 2016
Grant date	—

Abstract

A method of fabricating a composite semiconductor component comprising: (i) providing a bowed substrate comprising a wafer of synthetic diamond material having a thickness t d , the bowed substrate being bowed by an amount B and comprising a convex face and a concave face; (ii) growing a layer of compound semiconductor material on the convex face of the bowed substrate via a chemical vapour deposition technique at a growth temperature T to form a bowed composite semiconductor component comprising the layer of compound semiconductor material of thickness t sc on the convex face of the bowed substrate, the compound semiconductor material having a higher average thermal expansion coefficient than the synthetic diamond material between the growth temperature T and room temperature providing a thermal expansion mismatch ΔT ec ; and (iii) cooling the bowed composite semiconductor component, wherein the layer of compound semiconductor material contracts more than the wafer of synthetic diamond material during cooling due to the thermal expansion mismatch ΔT ec , wherein B, t d , t sc , and ΔT ec are selected such that the layer of compound semiconductor material contracts on cooling by an amount which off-sets bowing in the bowed substrate thus pulling the bowed composite semiconductor component into a flat configuration, the layer of compound semiconductor material having a tensile stress after cooling of less than 500 MPa.

First claim

1 - 6 . (canceled)

7 . A composite semiconductor component comprising:
a substrate comprising a wafer of synthetic diamond material; and a layer of compound semiconductor material on the substrate, wherein the layer of compound semiconductor material has a tensile stress of less than 500 MPa at room temperature.

8 . A composite semiconductor component according to claim 7 , wherein the tensile stress of the layer of compound semiconductor material is less than 450 MPa, 400 MPa, 350 MPa, 300 MPa, 250 MPa, or 210 MPa at room temperature.

9 . A composite semiconductor component according to claim 7 , wherein the substrate comprises a layer of single crystal material disposed between the wafer of synthetic diamond material and the layer of compound semiconductor material.

10 . A composite semiconductor component according to claim 7 , wherein a spacing between the layer of compound semiconductor material and the wafer of synthetic diamond material is no more than 5 μm, 3 μm, 2 μm, or 1 μm.

11 . A composite semiconductor component according to claim 7 , wherein the substrate comprises a layer of material disposed on an opposite side of the wafer of synthetic diamond material to the layer of compound semiconductor material, said layer of material having a lower thermal expansion coefficient than the synthetic diamond material at a temperature below 700° C.

12 . A composite semiconductor component according to claim 7 , wherein the synthetic diamond material has a thermal conductivity equal to or greater than 600 Wm −1 K −1 , 800 Wm −1 K −1 , 1000 Wm −1 K −1 , 1200 Wm −1 K −1 , or 1400 Wm −1 K −1 .

13 . A composite semiconductor component according to claim 7 , wherein the synthetic diamond material has a thickness in a range: 25 μm to 450 μm; 25 μm to 400 μm; 25 μm to 350 μm; 25 μm to 300 μm; 25 μm to 250 μm; 25 μm to 200 μm; 25 μm to 150 μm; 40 μm to 130 μm; or 50 μm to 100 μm.

14 . A composite semiconductor component according to claim 7 , wherein the synthetic diamond material is formed of a single crystal diamond material or a polycrystalline CVD diamond material.

15 . A composite semiconductor component according to claim 7 , wherein the wafer of synthetic diamond material comprises a free-standing synthetic diamond wafer or a wafer which comprises a layer of synthetic diamond material on a support substrate.

16 . A method of fabricating a composite semiconductor component according to claim 7 , the method comprising:
(i) providing a bowed substrate comprising a wafer of synthetic diamond material having a thickness t d , the bowed substrate being bowed by an amount B and comprising a convex face and a concave face; (ii) growing a layer of compound semiconductor material on the convex face of the bowed substrate via a chemical vapour deposition technique at a growth temperature T to form a bowed composite semiconductor component comprising the layer of compound semiconductor material of thickness t sc on the convex face of the bowed substrate, the compound semiconductor material having a higher average thermal expansion coefficient than the synthetic diamond material between the growth temperature T and room temperature providing a thermal expansion mismatch ΔT ec and (iii) cooling the bowed composite semiconductor component, wherein the layer of compound semiconductor material contracts more than the wafer of synthetic diamond material during cooling due to the thermal expansion mismatch ΔT ec ,
wherein B, t d , t sc , and ΔT ec are selected such that the layer of compound semiconductor material contracts on cooling by an amount which off-sets bowing in the bowed substrate thus pulling the bowed composite semiconductor component into a flat configuration, the layer of compound semiconductor material having a tensile stress after cooling of less than 500 MPa.

17 . A method according to claim 16 , wherein B, t d , t sc , and ΔT ec are selected such that the tensile stress of the layer of compound semiconductor material after cooling is less than 450 MPa, 400 MPa, 350 MPa, 300 MPa, 250 MPa, or 210 MPa.

18 . A method according to claim 16 , wherein the bowed substrate comprises a layer of single crystal material on the convex face of the bowed substrate, the layer of compound semiconductor material being grown on said layer of single crystal material.

19 . A method according to claim 16 , wherein the bowed substrate comprises a layer of material on the concave face of the bowed substrate which has a lower average thermal expansion coefficient than the synthetic diamond material between the growth temperature T and room temperature, said layer of material having a thermal expansion coefficient and thickness which are selected to contribute in off-setting the bowing in the bowed substrate during cooling.

20 . A method according to claim 16 , wherein the wafer of synthetic diamond material has a thermal conductivity equal to or greater than 600 Wm −1 K −1 , 800 Wm −1 K −1 , 1000 Wm −1 K −1 , 1200 Wm −1 K −1 , or 1400 Wm −1 K −1 .

21 . A method according to claim 16 , wherein the thickness t d of the wafer of synthetic diamond material is in a range: 25 μm to 450 μm; 25 μm to 400 μm; 25 μm to 350 μm; 25 μm to 300 μm; 25 μm to 250 μm; 25 μm to 200 μm; 25 μm to 150 μm; 40 pm to 130 μm; or 50 μm to 100 μm.

Assignees

• Element Six Ltd

Inventors

• Mollart Timothy
• Jiang Quanzhong
• Edwards Michael John
• Allsopp Duncan
• Bowen Christopher Rhys
• Wang Wang Nang

Classifications

• H10P14/3416

  Nitrides · CPC title

• H10P14/3414

  being group IIIA-VIA materials · CPC title

• H10P14/3402

  characterised by the chemical composition · CPC title

• H10P14/3256

  Microstructure · CPC title

• H10P14/3211

  Silicon, silicon germanium or germanium · CPC title