Planar technology for producing light-emitting devices

• US 5,998,232 A
• Filed: 01/14/1999
• Issued: 12/07/1999
• Est. Priority Date: 01/16/1998
• Status: Expired due to Fees

• Current Assignee: Implant Sciences Corporation
• Original Assignee: Implant Sciences Corporation
• Inventors: Maruska, H. Paul
• Primary Examiner(s): Fahmy, Wael
• Assistant Examiner(s): Pham, Long
• Application Number:
  US09/231,689
• Time in Patent Office: 327 Days
• Field of Search: 438/45, 438/46, 438/29, 257/13, 257/21, 257/615, 257/745, 257/189
• US Class Current: 438/46
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/325 characterised by the doping materials
• CPC Class Codes: H01S 5/02216 Butterfly-type, i.e. with electrode pins extending horizontally from the housings
• CPC Class Codes: H01S 5/0234 Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

The present invention relates to a novel planar technology approach utilizing ion implantation to improve the fabrication procedure for manufacturing nitride light-emitting and laser diodes. The simplified processing significantly reduces the costs of manufacturing these devices and allows flip-chip bonding to be used for efficient heat removal, yielding much brighter LEDs and more powerful lasers.

Claims

1. A method for producing a semiconductor device suitable for use as a light-emitting diode or laser diode comprising

a. providing a transparent substrate capable of supporting single crystal nitride growth having disposed sequentially thereon:

a first layer of an n-type doped first nitride compound,

at least one additional layer which may be doped or undoped comprising a second nitride compound or a nitride alloy, and

a final topmost layer of an undoped third nitride compound;

b. applying an n-type dopant to a peripheral portion of the topmost layer by ion implantation under conditions such that the n-type dopant permeates through the topmost layer and at least a portion of the additional layer or thereby forming an implanted n-type region; and

c. applying a p-type dopant to a central region of the top-most layer by ion implantation under conditions such that the p-type dopant permeates through the topmost layer thereby forming a p-type implanted region.

2. The method of claim 1 wherein the substrate is selected from the group consisting of sapphire, spinel and silicon carbide.

3. The method of claim 2 wherein the substrate is sapphire.

4. The method of claim 1 wherein said first layer is selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these.

5. The method of claim 1 wherein said additional layer is selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these.

6. The method of claim 1 wherein the topmost layer comprises undoped gallium nitride or an alloy of indium nitride and gallium nitride.

7. The method of claim 1 wherein the n-type dopant is selected from the group consisting of silicon, germanium, oxygen, sulfur and combinations thereof.

8. The method of claim 1 wherein the p-type dopant is selected from the group consisting of beryllium, magnesium, calcium, carbon, zinc and combinations thereof.

9. The method of claim 1 further comprising the step of applying metal contacts to the surfaces of the n-type and the p-type implanted regions after step (c) thereby forming reflective surfaces capable of reflecting light through the substrate.

10. The method of claim 9 further comprising the step of disposing the device on a lead frame with the transparent substrate facing upward to allow unobstructed emission of the light.

11. The method of claim 1 wherein the device comprises a square diode.

12. The method of claim 1 wherein the device comprises a rectangular diode having two broad sides and two narrow sides.

13. The method of claim 12 further comprising the step of applying a dielectric mirror at each narrow side of the device, and disposing the device onto a lead frame with the substrate facing upwards.

14. The method of claim 1 further comprising the step of annealing the device in an inert nitrogen gas at a temperature of at least about 1000°

C.

15. The method of claim 10 further comprising the step of bonding the device to a chip carrier.

16. A method for producing a bright, high-yield green or blue LED comprising the steps of

a. providing a sapphire substrate having disposed sequentially thereon:

a first layer of n-type nitride selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these,

at least one additional layer which may be doped or undoped comprising a nitride compound selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these, and

a final topmost layer of undoped gallium nitride or an alloy of indium nitride and gallium nitride;

b. producing a conducting channel which permeates from the topmost layer to the first layer by ion implantation of a donor selected from the group consisting of silicon, germanium, sulfur and oxygen to a peripheral region of the LED thereby forming an n-type implanted region in a ring or border pattern around the circumference of the LED;

c. producing a p-type surface layer by ion implantation of an acceptor ion selected from the group consisting of beryllium, magnesium, calcium, carbon, and zinc to a central region of the LED thereby forming a p-type implanted region located within the n-type region;

d. annealing the implanted device in flowing nitrogen gas at a temperature of at least about 1000°

C.;

e. disposing two metal contacts on the surfaces of the n-type and the p-type implanted regions thereby forming a reflective surface capable of reflecting light through the substrate; and

f. bonding the device to a chip carrier.

17. The method of claim 16 further comprising the step of forming on the LED after step (c) a protective capping layer comprising a nitride material.

18. A method for producing a high intensity, high-yield, green, blue or ultraviolet laser diode comprising the steps of:

a. providing a sapphire substrate having disposed thereon;

a first layer of n-type nitride selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these,

at least one additional layer which may be doped or undoped comprising a nitride compound selected from the group consisting of gallium nitride, aluminum nitride, indium nitride, thallium nitride, scandium nitride, yttrium nitride, lanthanum nitride, and any alloys, mixtures and combinations of these, and

final topmost layer of undoped gallium nitride or an alloy of indium nitride and gallium nitride;

b. producing a conducting channel which permeates from the topmost layer to the first layer by ion implantation of a donor selected from the group consisting of silicon, germanium, sulfur and oxygen to a peripheral region of the diode thereby forming an n-type implanted region, wherein the diode has a rectangular shape having long and narrow sides, and wherein the channel forms two parallel continuous bands along the long sides;

c. producing a p-type surface layer by ion implantation of an acceptor ion selected from the group consisting of beryllium, magnesium, calcium, carbon, and zinc to a central region of the device thereby forming a p-type implanted region located centrally between the bands of the n-type regions;

d. annealing the implanted device in flowing inert gas at a temperature of at least about 1000°

C.;

e. disposing two metal contacts on the surfaces of the n-type and p-type implanted regions thereby forming electrical contacts;

f. applying dielectric mirrors at each narrow side of the rectangular diode; and

g. bonding the device to a chip carrier.

19. The method of claim 18 further comprising the step of forming a protective capping layer comprising a nitride material on the diode after step (c).

20. An LD produced according to the method of claim 18.