Method for producing optoelectronic semiconductor chips

Patent metadata

Field	Value
Publication number	US-2016079468-A1
Application number	US-201514857698-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Sep 17, 2014
Publication date	Mar 17, 2016
Grant date	—

Abstract

The method is designed for producing optoelectronic semiconductor chips and comprises the steps:
A) providing a carrier substrate ( 1 ), B) applying a semiconductor layer sequence ( 2 ) onto the carrier substrate ( 1 ), and C) detaching the finished semiconductor layer sequence ( 2 ) from the carrier substrate ( 1 ) by means of laser radiation (R) with a wavelength (L) through the carrier substrate ( 1 ), wherein
the semiconductor layer sequence ( 2 ) has a buffer layer stack ( 20 ) and a functional stack with an active layer ( 21 ) for generating light ( 22 ), the absorber layer ( 23 ) is grown within the buffer layer stack ( 20 ) from a material for absorbing the laser radiation (R) and all the remaining layers ( 24 and 25 ) of the buffer layer stack ( 20 ) are transmissive to the laser radiation (R), a material of the functional stack ( 22 ) preferably has an absorbent action for the laser radiation (R), and in step C) the semiconductor layer sequence ( 2 ) is detached in the region of the absorber layer ( 23 ).

First claim

1 . Method for producing optoelectronic semiconductor chips having the steps:
A) providing a carrier substrate, B) applying a semiconductor layer sequence onto the carrier substrate, and C) detaching the finished semiconductor layer sequence
(2) from the carrier substrate by means of laser radiation (R) with a wavelength through the carrier substrate), wherein
the semiconductor layer sequence, in the direction away from the carrier substrate, has a buffer layer stack and a functional stack,
the functional stack comprises at least one active layer for generating light,
at least one absorber layer is located within the buffer layer stack,
the absorber layer is formed from a material for absorbing the laser radiation and all the remaining layers of the buffer layer stack are transmissive to the laser radiation, and
in step C) the semiconductor layer sequence is detached from the carrier substrate in the region of the absorber layer,

wherein the absorber layer in step C) is located at a maximum of a radiant intensity of the laser radiation in the semiconductor layer sequence.

2 . Method according to claim 1 ,
in which a distance between the absorber layer and edges of buffer layer stack amounts, along a growth direction of the semiconductor layer sequence, to at least L/(4 n), wherein L is the wavelength of the laser radiation and n the average refractive index of the buffer layer stack, wherein a thickness of the buffer layer stack is between 80 nm and 5 μm inclusive, wherein the semiconductor layer sequence is grown epitaxially or by means of sputtering on the carrier substrate such that the carrier substrate is a growth substrate, and wherein a material of the functional stack has an absorbent action for the laser radiation.

3 . Method according to claim 1 ,
in which the absorber layer is located, counting from the carrier substrate, at the first maximum of the radiant intensity in the buffer layer stack.

4 . Method according to claim 1 ,
in which the absorber layer is located, counting from the carrier substrate, at the second maximum of the radiant intensity in the buffer layer stack.

5 . Method according to claim 1 ,
in which the buffer layer stack has a thickness of [(1+2 N) L]/(4 n), wherein L is the wavelength of the laser radiation, n is the average refractive index of the buffer layer stack and N is a natural number greater than or equal to one.

6 . Method according to claim 1 ,
in which the buffer layer stack in the region between the carrier substrate and the absorber layer is an antireflection layer for the laser radiation.

7 . Method according to claim 6 ,
in which the buffer layer stack in the region between the absorber layer and the functional stack is a Bragg reflector for the laser radiation.

8 . Method according to claim 7 ,
wherein the exactly one absorber layer has a thickness of L/(2 n A ), wherein L is the wavelength of the laser radiation and n A is the refractive index of the absorber layer.

9 . Method according to claim 1 ,
in which a thickness of the exactly one absorber layer, along the growth direction, amounts to between 1.5 nm and L/(12 n A ) inclusive, wherein L is the wavelength of the laser radiation and n A is the refractive index of the absorber layer.

10 . Method according to claim 1 ,
in which the buffer layer stack has a superlattice with a plurality of alternating layers with a high and with a low refractive index, wherein a layer thickness of the alternating layers is in each case between 1.5 nm and 15 nm inclusive.

11 . Method according to claim 10 ,
in which the superlattice comprises between 5 and 50 pairs inclusive of the alternating layers, wherein a refractive index difference between the alternating layers is between 0.1 and 0.35 inclusive.

12 . Method according to claim 1 ,
in which the carrier substrate is a sapphire substrate and the semiconductor layer sequence is based on AlInGaN, wherein the absorber layer is grown from GaN or InGaN and the remaining layers of the buffer layer stack are grown from AlN and/or AlGaN and the layer of the functional stack which is closest to the carrier substrate is a GaN layer, and wherein the GaN layer of the functional stack exceeds the thickness of the buffer layer stack by at least a factor of 2.

13 . Method according to claim 12 ,
in which the wavelength of the laser radiation is between 240 nm and 380 nm inclusive, an energy density of the pulsed laser radiation at the absorber layer is between 100 mJ/cm 2 and 850 mJ/cm 2 inclusive per pulse and a pulse duration of the laser radiation amounts to between 2 ns and 40 ns inclusive.

14 . Method according to claim 13 ,
with which light-emitting diode chips are produced which comprise the functional stack and at least part of the buffer layer stack.

Assignees

• Osram Opto Semiconductors Gmbh

Inventors

• Gomez-Iglesias Alvaro
• Hirmer Marika
• Frey Alexander
• Zini Lorenzo
• Laux Harald

Classifications

• H10H20/825

  containing nitrogen, e.g. GaN · CPC title

• H10H20/821

  of the light-emitting regions, e.g. non-planar junctions · CPC title

• H10H20/815

  having stress relaxation structures, e.g. buffer layers · CPC title

• H10H20/814

  having reflecting means, e.g. semiconductor Bragg reflectors · CPC title

• H10H20/82

  Roughened surfaces, e.g. at the interface between epitaxial layers · CPC title