Manufacturing method for nitride semiconductor device and nitride semiconductor light emitting device obtained with the same

• US 7,566,639 B2
• Filed: 09/15/2006
• Issued: 07/28/2009
• Est. Priority Date: 09/16/2005
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Kohda, Shinichi
• Primary Examiner(s): Tran; Minh-Loan T
• Assistant Examiner(s): AHMED, SELIM U
• Application Number:
  US11/521,553
• Publication Number:
  US 20070063215A1
• Time in Patent Office: 1,047 Days
• Field of Search: 438/797, 438/460, 438/463, 257/683, 257/723, 257/E21.599
• US Class Current: 438/463
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01S 5/0201 Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth
• CPC Class Codes: H01S 5/0202 Cleaving
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/2214 based on oxides or nitrides
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

Processed traces are formed on at least a part of intended cutting lines A along which a wafer (10) where a nitride semiconductor lamination portion (6) is formed on a GaN based substrate (1) is divided into chips, by irradiating with a laser beam LB having a wavelength which is longer than the band gap wavelength of the GaN based substrate 1 and an electrical field intensity which causes a multiple photons absorption, while adjusting the focal point to a constant depth d within the GaN based substrate (1) from the back surface of the wafer. After that, the wafer (10) is divided into chips along cutting starting points (12) which are formed in the vicinity of the processed traces by hitting with an impact. As a result, the wafer can be easily divided into chips, and in particular, end faces of a resonator can be formed with cleavage planes when an LD is formed.

Claims

1. A manufacturing method for a nitride semiconductor device, comprising the steps of:

(a) forming a semiconductor lamination portion formed of nitride semiconductor layers which include at least an n-type layer and a p-type layer on a surface of a wafer made of a GaN based substrate,

(b) forming processed traces in at least a portion of intended cutting lines, along which the wafer is divided into chips, and in a certain depth within the GaN based substrate and with intervals of approximately 1.5 μ

m to 3.0 μ

m between adjacent processed traces, by irradiating a laser beam having a wavelength that is longer than a wavelength corresponding to a band gap energy of the GaN based substrate and an electrical field intensity, by which multiple photons absorption is caused, and

(c) dividing the wafer along cutting starting points which are formed in the vicinity of the processed traces.

2. The manufacturing method for a nitride semiconductor device according to claim 1, wherein the processed traces are formed by creating holes.

3. The manufacturing method for a nitride semiconductor device according to claim 1, wherein a wavelength of the laser beam to be irradiated is longer than the wavelength corresponding to the band gap energy of the GaN based substrate and no greater than three times of the wavelength.

4. The manufacturing method for a nitride semiconductor device according to claim 3, wherein the GaN based substrate is made of GaN and the wavelength of the laser beam to be irradiated is 500 nm to 700 nm.

5. The manufacturing method for a nitride semiconductor device according to claim 1, wherein an intensity T of the laser beam to be irradiated is 5×

10⁹ W/cm²<

T<

2×

10¹⁰ W/cm².

6. The manufacturing method for a nitride semiconductor device according to claim 1, wherein the semiconductor lamination portion, formed of the nitride semiconductor layers is formed so as to compose a laser diode having a light emitting region in stripe form, and wherein the wafer is divided into chips so that an end face of the light emitting region in stripe form becomes a plane of cleavage.

7. The manufacturing method for a nitride semiconductor device according to claim 1, wherein the semiconductor lamination portion formed of the nitride semiconductor layers is formed so as to compose a light emitting diode.

8. A manufacturing method for a nitride semiconductor device, comprising the steps of:

(a) forming a semiconductor lamination portion formed of nitride semiconductor layers which include at least an n-type layer and a p-type layer on a surface of a wafer made of a GaN based substrate,

(b) forming processed traces in at least a portion of intended cutting lines, along which the wafer is divided into chips, and in a certain depth within the GaN based substrate, by irradiating a laser beam having a wavelength that is longer than a wavelength corresponding to a band gap energy of the GaN based substrate and an electrical field intensity, by which multiple photons absorption is caused, from a back surface side of the wafer, and

(c) dividing the wafer along cutting starting points which are formed in the vicinity of the processed traces by hitting the wafer with an impact,

wherein a wavelength of the laser beam to be irradiated is set to such a wavelength that an absorption coefficient of the substrate is within a range from 0.1 cm<sup>−

1</sup> to 100 cm<sup>−

1</sup> for the wavelength corresponding to the band gap energy of the substrate in a relation of a material of the substrate and the wavelength of the laser beam.

9. The manufacturing method for a nitride semiconductor device according to claim 8, wherein an absorption coefficient of the substrate is adjusted within a range from 0.1 cm⁻

1 to 100 cm<sup>−

1</sup> for the wavelength corresponding to the band gap energy of the substrate, by doping an impurity into the substrate.

10. A manufacturing method for a nitride semiconductor device, comprising the steps of:

(a) forming a semiconductor lamination portion formed of nitride semiconductor layers which include at least an n-type layer and a p-type layer on a surface of a wafer made of a GaN based substrate,

(b) forming processed traces in at least a portion of intended cutting lines, along which the wafer is divided into chips, and in a certain depth within the GaN based substrate, by irradiating a laser beam having a wavelength that is longer than a wavelength corresponding to a band gap energy of the GaN based substrate and an electrical field intensity, by which multiple photons absorption is caused, from a back surface side of the wafer, and

(c) dividing the wafer along cutting starting points which are formed in the vicinity of the processed traces by hitting the wafer with an impact,

wherein a thickness of the GaN based substrate is 100 μ

m to 400 μ

m and the depth on which the processed traces are formed is in a range between 5 μ

m from the back surface of the substrate, and 15 μ

m from a front surface which is an opposite surface to the back surface of the substrate.

11. The manufacturing method for a nitride semiconductor device according to claim 10, wherein second processed traces are formed at a location of 5 μ

m to 50 μ

m away from the processed traces perpendicularly to the surface of the GaN based substrate.

12. A nitride semiconductor light emitting device, comprises:

a GaN based substrate, and

a semiconductor lamination portion which is formed by laminating nitride semiconductor layers including at least an n-type layer and a p-type layer so as to form a light emitting layer on the GaN based substrate,

wherein a chip is formed by dividing a wafer formed of the GaN based substrate and the semiconductor lamination portion into chips, and

wherein processed traces which are formed by irradiating a laser beam inside the substrate are exposed on at least one side surface of the chip, and the one side surface is formed as a broken surface caused by the processed traces, and processed traces are formed with intervals of approximately 1.5 μ

m to 3 μ

m therebetween.

13. The nitride semiconductor light emitting device according to claim 12, wherein the semiconductor lamination portion is formed so as to compose a laser diode having a light emitting region in stripe form, and wherein the chip is formed from the wafer by dividing, so that an end face of the light emitting region in stripe form is a plane of cleavage formed by cleaving which is caused on the processed traces.

14. A manufacturing method for a nitride semiconductor device, comprising the steps of:

(a) forming a semiconductor lamination portion formed of nitride semiconductor layers which include at least an n-type layer and a p-type layer on a surface of a wafer made of a GaN based substrate,

(b) forming processed traces in at least a portion of intended cutting lines, along which the wafer is divided into chips, and in a certain depth within the GaN based substrate and with intervals of approximately 1.5 μ

m to 3.0 μ

m between adjacent processed traces, by irradiating a laser beam having a wavelength that is 1.1 times to 2 times a wavelength corresponding to a band gap energy of the GaN based substrate and an electrical field intensity, by which multiple photons absorption is caused, and

(c) dividing the wafer along cutting starting points which are formed in the vicinity of the processed traces.

15. The manufacturing method for a nitride semiconductor device according to claim 14, wherein the GaN based substrate is made of GaN and the wavelength of the laser beam to be irradiated is 500 nm to 700 nm.

16. A manufacturing method for a nitride semiconductor device, comprising the steps of:

(a) forming a semiconductor lamination portion formed of nitride semiconductor layers which include at least an n-type layer and a p-type layer on a surface of a wafer made of a GaN based substrate,

(b) forming processed traces in at least a portion of intended cutting lines, along which the wafer is divided into chips, and in a certain depth within the GaN based substrate, by irradiating a laser beam having a wavelength that is longer than a wavelength corresponding to a band gap energy of the GaN based substrate and having an electrical field intensity by which multiple photons absorption is caused, and

(c) dividing the wafer along cuffing starting points which are formed in the vicinity of the processed traces,

wherein the processed traces are formed with intervals of two times or more of a wavelength of the laser beam and less than 10 μ

m between adjacent processed traces.