WO1998054757A1

WO1998054757A1 - Method for etching iii-v semiconductor material

Info

Publication number: WO1998054757A1
Application number: PCT/DE1998/001434
Authority: WO
Inventors: Gerhard Franz
Original assignee: Siemens Aktiengesellschaft
Priority date: 1997-05-26
Filing date: 1998-05-26
Publication date: 1998-12-03

Abstract

The aim of the invention is to increase the etch rate for dry-etching III-V semiconductor materials. To this end, BCl3 gas and Cl2 gas are excited together in a plasma and the mixture of these excited gases is brought into contact with the semiconductor material. The inventive method provides a quicker means of producing LED's on a GaN base and AlAs, GaAs and GaP LED's, VCSEL's and edge emission lasers.

Description

A. CLASSIFICATION OF THE APPLICATION SUBJECT

IPK 6 H01L21 / 306

According to the International Patent Classification (IPK) or according to the national classification and the IPK

B. RESEARCHED AREAS

Researched minimum test substance (classification system and classification symbols)

IPK 6 H01L

Researched publications but not part of the minimum test substance, insofar as these fall under the researched areas

Electronic database consulted during international research (name of database and possibly used search term)

C. MATERIALS REQUIRED

Category ⁰ Name of the publication, as well as required stating the relevant parts regarding claim no

PATENT ABST ACTS OF JAPAN 1,2,4-6 vol. 97, no. 7, September 30, 1997

- & JP 09 129930 A (NITTA ET AL),

May 16, 1997 is a summary

- & US 5,789,265 A (NITTA ET AL) 1,2,4-6

August 4, 1998 is a summary

EP 0 144 142 A (NAGASAKA ET AL) 1,2,4,5,

June 12, 1985 7 see page 6, line 11 - page 7, line 1 1,3,5-7

Further publications can be found in the continuation of field C in See Appendix Patent Family

° Special categories of specified publications T "Later publication after the international filing date

'A' Publication that defines the general state of the art, or that has been published on the date of the prontent, but with which the application should not be regarded as particularly significant does not conflict, but only to understand the principle on which the invention is based or on which it is based

"E" older document, which was however only published on or after the international theory of filing date "X" publication of particular importance, the claimed invention

"" Publication that is likely to make a claim for priority doubtful only on the basis of this publication, cannot be made new or appear to be apparent, or by which the publication date of an inventive step is considered to be evidence of other publications mentioned in the search report. "Y" publication of particular importance , the claimed invention, or which is for some other particular reason (such as cannot be deemed to be inventive), when the publication is with one or more others

"O" publication which relates to an oral disclosure, publications in this category and is related to use, exhibition or other means which makes this connection obvious to a person skilled in the art

"P" publication published before the international filing date but after the claimed patent date "&" publication belonging to the same family of patents

Date of completion of the international search Date of dispatch of the international search report

October 26, 1998 10/11/1998

Name and postal address of the International Searching Authority Authorized agent European Patent Office, PB 5818 Patentlaan 2 NL - 2280 HV Ri | swιjk Tel (+ 31-70) 3 ₄ 0-20 0, Tx 31 651 epo nl, Fax (+ 31-70) 3 Q-3016 Gori, P

Form PCT / ISA / 210 (Sheet 2) (July 1992) C. (Continued) MATERIALS REQUIRED

Category ⁰ Name of the publication, if necessary stating the relevant parts regarding claim no

K0ZI0R T E ET AL: "THROUGH WAFER VIA HOLE 1,5,7

ETCHING OF NOVEL DEVICE STRUCTURES WITH

ALGAAS CONTAINING BUFFER LAYERS USING A

BCL3 / CL2 PLASMA "

JOURNAL OF THE ELECTROCHEMICAL SOCIETY,

Vol. 137, No. 9, September 1990, page 865C

XP000210071 see summary

Y, P US 5,693,180 A (FURUKAWA ET AL) 1,5,6

December 2, 1997 see summary

- & JP 08 293489 A (FURUKAWA ET AL) 1.5.6

November 5, 1996 see figures

US 5,034,092 A (LEBBY ET AL) July 23, 1991 1,5,7 see summary

PEARTON S J ET AL: "DRY ETCHING 0F THIN-FILM INN, AIN AND GAN" SEMIC0NDUCT0R SCIENCE AND TECHNOLOGY, Vol. 8, No. 2, February 1, 1993, pages 310-312, XP000339499 see summary

Form PCT / ISA / 210 (continuation of sheet 2) (July 1992) Information on publications belonging to the same patent family

PCT / DE 98/01434

In the search report date of the mιtglιed (er) the date of the cited patent document publication patent family publication

EP 144142 12-06-1985 JP 60202941 A 14-10-1985 P 1601731 C 27-02-1991 P 2024016 B 28-05-1990 JP 60117631 A 25-06-1985 DE 3485368 A 30-01-1992 US 4640737 A 03-02-1987

US 5693180 A 02-12-1997 JP 8293489 A 05-11-1996

US 5034092 A 23-07-1991 JP 2715754 B 18-02-1998 JP 4262528 A 17-09-1992

Form PCT / ISA / 210 (Appendix Patθntfamιlιe) (Julι 1992) 1 description

Process for etching III-V semiconductor material

The invention relates to a method for etching a III-V semiconductor material according to the preamble of claim 1.

Methods of the type mentioned are for example from J. Electrochem. Soc. 143, 3394 (1996) and 7th Federal German Conference on Plasma Technology, 1996, pp. 83-84.

In the case of J. Electrochem. Soc. In known processes, nitrogen gas is added to the BCl3 gas as a further reactive gas and, as a result, when etching InGaP and InP in a plasma produced by electron cyclotron resonance, a considerably higher etching rate is obtained than with BCl3 gas alone.

In the process known from the Federal German Conference on Plasma Technology, an SFg gas is added to the BCl3 ~ gas as a further reactive gas and thus when etching

GaAs, but not AlGaAs, obtained a higher etching rate in capacitively coupled plasmas than obtained with BCl3 gas alone.

The inventive method specified in claim 1 has the advantage that AlGaAs with a higher etching rate than with

BCl3 gas alone can be etched. In addition, there is the advantage that all III-V semiconductor materials can be etched individually but also mixed with one another using the method according to the invention, and a particular advantage can be seen in the fact that the materials GaAs, AlGAs, AlAs, GaN, InGaN, GaP and InSb individually but also mixed together with a higher etching rate than can be etched with BCl3 gas alone. With the materials GaN and InGaN, the etching rate is advantageously doubled in comparison with the etching with BCl3 ~ gas alone, with the materials GaAs, AlGaAs, AlAs, GaP and InSb it increases regardless of whether these substances individually or are mixed together, advantageously by a factor of up to 10.

In the method according to the invention, the plasma can advantageously be generated as before, for example as in reactive ion etching (RIE), e.g. in a parallel plate reactor, or with the method of electron cyclotron resonance (ECR).

It is advantageous to use a mixture which has BCI ₃ - and Cl2 "gas in equal parts, for example a 1: 1 mixture of these two gases, since with such a mixture the density of excited chlorine molecules is advantageously maximum, but the density of the single ionized Cl ions do not increase detectably, but - due to the dilution with BCI3 - even decrease, but an increase in the etching rate is also observed with all other mixing ratios Pressure and temperature conditions can be obtained in the plasma.

The method according to the invention is preferred and advantageously - for etching the surface of a substrate having GaN and / or InGaN in order to produce a relief structure for a blue to yellow-emitting LED on the surface of the substrate, the relief structure being based on a substrate made of GaN and / or InGaN existing surface applied etching mask is defined from a material that is not attacked by the excited gas mixture or at least less strongly than the substrate material GaN and / or InGaN, and - for etching the surface of a GaAs and / or AlGaAs and / or AlAs and / or having GaP and / or InSb

Substrate for production e.g. a relief structure for a VCSEL or an LED or an edge emitting laser

Claims

the surface of the substrate, the relief structure being defined by an etching mask applied to the surface consisting of the substrate material GaAs and / or AlGaAs and / or AlAs and / or GaP and / or InSb and made of a material that is not or not excited by the gas mixture excited in the plasma is attacked at least less strongly than the substrate material GaAs and / or AlGaAs and / or AlAs and / or GaP and / or InSb.

The substrate can contain two or more different of the specified substrate materials separately or mixed with one another in any combination. For example, the substrate can have several layers, each of which individually contains one or more of the specified substrate materials, the composition of the substrate materials being able to differ from layer to layer.

LED stands for light emitting diode and VCSEL for vertical cavity surface emitting laser.

The invention is explained in more detail by way of example in the following description with reference to the figure.

The figure shows a detail and in cross section of a substrate made of III-V semiconductor material, on the surface of which a relief structure in the form of a mesa is produced with the aid of an etching mask using the method according to the invention.

The figure is schematic and not to scale.

In the figure, the substrate is denoted by 1, its surface to be etched by 10, an etching mask by 2 and the plasma containing the two reactive gases BCI3 and CI2 by 3.

The substrate 1 is, for example, an afer made of III-V semiconductor material with an originally flat surface 10 to be etched. The etching mask 2, which defines and forms the mesa 11 to be produced, is applied to this surface consists of a material which is not attacked by the mixture of BCI3 and Cl2 ~ gas excited in the plasma 3 or at least less attacked on the surface 10 than the semiconductor material of the substrate 1.

The etching mask 2 can consist, for example, of a dielectric, preferably aluminum oxide and / or silicon dioxide and / or silicon nitride, and / or of photoresist.

The plasma 3 can be generated as in the known RIE or with ECR. Pressures between 1 and 10 Pa, HF powers of approximately 1/3 to 3/4 W / cm ² at 13.56 MHz and DC bias voltages between 300 and 600 V are preferably used in the RIE, pressures below 1 / 3 Pa, MW powers up to 1000 W at 2.45 GHz and HF powers up to

1 W / cm ² at 13.56 MHz.

In the figure, the originally flat surface 10 of the substrate 1 outside the etching mask 2 is already to a depth t below the non-etched surface 10 under the etching mask due to the action of the gas mixture excited in the plasma 3

2 etched and thus produces a raised mesa 11, the height of which is equal to the depth t by which the surface 10 is etched deeper outside the etching mask 2.

Such mesas 11 or other relief structures are required, for example, in the production of blue to yellow-emitting LEDs based on GaN and VCSELs, edge-emitting lasers and yellow to infrared-emitting LEDs based on GaAs and / or AlAs and / or GaP and / or InSb, and the production is the longest lasting step with the required etching depths t of up to 10 μm.

The method according to the invention advantageously enables faster production and thus a higher throughput when processing substrates 1 in the form of wafers for blue to yellow-emitting GaN-based LEDs and