KR960003752B1 - Etching method of mesa-structure for laser diode - Google Patents
Etching method of mesa-structure for laser diode Download PDFInfo
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- KR960003752B1 KR960003752B1 KR1019920026881A KR920026881A KR960003752B1 KR 960003752 B1 KR960003752 B1 KR 960003752B1 KR 1019920026881 A KR1019920026881 A KR 1019920026881A KR 920026881 A KR920026881 A KR 920026881A KR 960003752 B1 KR960003752 B1 KR 960003752B1
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- 238000005530 etching Methods 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 18
- 239000000758 substrate Substances 0.000 claims abstract description 10
- MODGUXHMLLXODK-UHFFFAOYSA-N [Br].CO Chemical compound [Br].CO MODGUXHMLLXODK-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 11
- 125000000896 monocarboxylic acid group Chemical group 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 3
- 238000002513 implantation Methods 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 abstract description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 abstract 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 abstract 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract 2
- 235000011007 phosphoric acid Nutrition 0.000 abstract 2
- 229910052581 Si3N4 Inorganic materials 0.000 abstract 1
- 229910052681 coesite Inorganic materials 0.000 abstract 1
- 229910052906 cristobalite Inorganic materials 0.000 abstract 1
- 238000000151 deposition Methods 0.000 abstract 1
- 239000000377 silicon dioxide Substances 0.000 abstract 1
- 235000012239 silicon dioxide Nutrition 0.000 abstract 1
- 229910052682 stishovite Inorganic materials 0.000 abstract 1
- 229910052905 tridymite Inorganic materials 0.000 abstract 1
- 238000001039 wet etching Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N methanol Substances OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
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Abstract
Description
제 1 도는 종래의 InP 계열 PBH-LD 구조의 단면도.1 is a cross-sectional view of a conventional InP series PBH-LD structure.
제 2 도는 본 발명에 따른 PBH-LD 식각 공정도.2 is a PBH-LD etching process diagram according to the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
1 : n+-InP 기판 2 : InP 에피텍셜층1: n + -InP substrate 2: InP epitaxial layer
3 : InGaAsP 활성층 4 : p-InP 에피텍셜층3: InGaAsP active layer 4: p-InP epitaxial layer
5 : p-InP 에피텍셜층 6 : n-InP 에피텍셜층5: p-InP epitaxial layer 6: n-InP epitaxial layer
7 : p-InP 에피텍셜층 8 : n-InGaAsP 에피텍셜층7: p-InP epitaxial layer 8: n-InGaAsP epitaxial layer
8' : Zn-확산 영역 9 : n+-InP 기판8 ': Zn-diffusion region 9: n + -InP substrate
10 : n-InP 에피텍셜층 11 : InGaAsP 활성층10: n-InP epitaxial layer 11: InGaAsP active layer
12 : p-InP 에피텍셜층 13 : SiO2또는 Si3N4마스크층12 p-InP epitaxial layer 13 SiO 2 or Si 3 N 4 mask layer
21 : n-InGaASp 도파관층21: n-InGaASp waveguide layer
본 발명은 화합물 반도체의 레이저 다이오드(Laser Diode ; LD)의 습식식각에 관한 것으로, 특히 레이저 다이오드의 메사(Mesa) 형성 식각 방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wet etching of laser diodes (LDs) in compound semiconductors, and more particularly, to a method for forming mesa formation of laser diodes.
레이저 다이오드(LD)는 문턱 전류 이상으로 인가하면 단일 파장의 레이저 비임이 나오는 소자이다. InP 계열 레이저 다이오드는 설계 구조에 따라 여러층으로 구성되고 적당한 에너지 갭을 갖는 층을 사용하여 1.3㎛ 혹은 1.55㎛의 레이저를 만들어 주로 장거리 광통신 시스템의 핵심 부품인 신호원으로 사용되며, 그 외에 측정 장비 등에도 사용된다.The laser diode LD is a device that emits a laser beam of a single wavelength when applied above the threshold current. InP series laser diode is composed of several layers according to the design structure and uses 1.3mm or 1.55㎛ laser using layers with suitable energy gap, and is mainly used as a signal source, which is a key part of long-distance optical communication system. It is also used.
일반적으로 LD의 특성 향상을 목적으로 설계되는 메사 구조의 레이저 다이오드 제작과정은 습식식각을 통해 이루어지게 되는데, 광통신용 LD는 대부분 매립된 헤테로 구조(Buried Heterostructure)(BH)로 되어 있고, 빛을 발생하는 활성층을 매립시켜서 빛을 활성층으로 모아 단일 모드의 레이징(Lasing)이 되도록 하는 구조로서, 그 구조는 식각된-메사 매립 헤테로 구조(Etched-Mesa Buried Heterostructure), 이중-채널 플래너 매립 헤테로 구조(Double-Channel Planar Buried Heterostructrue), 스트립 매립 헤테로 구조(Strip-Buried Heterostructure), 채널-기판 매립 헤테로 구조(Channel-Substrate Buried Heterostructure), 메사-기판 매립 헤테로 구조(Mesa-Substrate Buried Heterostructure), 질량-이송 매립 헤테로 구조(Mass-Transported Buried Heterostructure), 플래너 매립 헤테로 구조(Planar Buried Heterostructure) 등이 있는데, 일반적으로 LD의 특성 향상을 목적으로 설계되는 메사 구조의 레이저 다이오드 제작과정은 습식식각을 통해 이루어지게 된다.In general, the mesa structure laser diode manufacturing process designed to improve the characteristics of LD is performed by wet etching. The LD for optical communication is mostly a buried heterostructure (BH), and generates light. A structure in which an active layer is embedded to collect light into an active layer to be a single mode lasing, and the structure is an etched-mesa buried heterostructure, a dual-channel planar buried heterostructure ( Double-Channel Planar Buried Heterostructrue, Strip-Buried Heterostructure, Channel-Substrate Buried Heterostructure, Mesa-Substrate Buried Heterostructure, Mass-Transfer Mass-Transported Buried Heterostructure, Planar Buried Heterostructure, etc. Typically a laser diode manufacturing process of the mesa structure is designed for the purpose of improving characteristics of the LD becomes done by wet etching.
종래 레이저 다이오드의 PBH 구조를 제 1 도를 통하여 살펴보면, 도면에서 1은 n+-InP 기판, 2는 n-InP 에피텍셜층, 3은 InGaAsP 활성층, 4는 p-InP 에피텍셜층, 5는 p-InP 에피텍셜층, 6은 n-InP 에피텍셜층, 7은 p-InP 에피텍셜층, 8은 n-InGaAsP 에피텍셜층, 8'는 Zn-확산 영역, 21은 n-InGaAsP 도파관층을 각각 나타낸다.Referring to the PBH structure of a conventional laser diode through FIG. 1, 1 is an n + -InP substrate, 2 is an n-InP epitaxial layer, 3 is an InGaAsP active layer, 4 is a p-InP epitaxial layer, and 5 is p. InP epitaxial layer, 6 n-InP epitaxial layer, 7 p-InP epitaxial layer, 8 n-InGaAsP epitaxial layer, 8 'Zn-diffusion region, 21 n-InGaAsP waveguide layer, respectively Indicates.
상기와 같은 종래의 레이저 다이오드(LD)형성을 위한 메사 형성 습식식각 기술은 LD 구조에 따라 층별 식각제를 선택하여 식각하는데, 즉, PBH(Planer Buried Heterostructure) 구조의 LD 제조 과정중 기존의 습식식각 방법은 2단계 식각 방법으로 되어 있다. 즉, 제 1 단계 식각은 0.2% 브롬(Br)-메탄올 혹은, HCl : H2O2: CH3COOH(3 : 1 : 36) 식각제로 식각한 다음 연속적으로 제 2 단계를 HCl : H3PO4(1 : 2) 식각제로 식각을 실시한다.The conventional mesa-forming wet etching technology for forming a laser diode (LD) is selected and etched by layered etchant according to LD structure, that is, conventional wet etching during LD manufacturing process of PBH (Planer Buried Heterostructure) structure. The method is a two-step etching method. That is, the first stage etching is performed by etching 0.2% bromine (Br) -methanol or HCl: H 2 O 2 : CH 3 COOH (3: 1: 36) etchant, and the second stage is successively prepared by HCl: H 3 PO 4 (1: 2) Etch with an etchant.
그러나 상기 종래의 PBH 구조 LD의 습식식각은, 첫째 제 1 식각제의 식각률의 불안정으로 인한 식각 재현성이 불량하고, 둘째 제 1 식각제의 언더컷트(Undercut )가 크므로 패턴 폭 및 활성층 폭이 불균일하며, 셋째 제 2 식각제의 수직 식각에 의한 에피텍셜층의 재현성에 매우 민감한 문제점이 있었다.However, the wet etching of the conventional PBH structure LD has a poor etching reproducibility due to the instability of the etching rate of the first etching agent, and the pattern width and the active layer width are uneven because the undercut of the first etching agent is large. Third, there is a problem that is very sensitive to the reproducibility of the epitaxial layer by the vertical etching of the second etchant.
상기 문제점을 해결하기 위하여 안출된 본 발명은 레이저 다이오드 제작 공정중 메사 구조를 형성하는 습식식각을 층별로 식각률(Etch Rate) 및 식각 특성이 양호한 식각제를 선택함으로써 식각된 표면, 식각 재현성, 식각 제어성 등을 향상시켜 소자의 성능향상을 도모하여 양호한 레이징(Lasing) 특성을 얻을 수 있는 레이저 다이오드의 메사 형성 식각 방법을 제공하는데 그 목적이 있다.In order to solve the above problems, the present invention selects an etchant having good etching rate and etching characteristics for each layer of wet etching forming a mesa structure during the laser diode fabrication process. It is an object of the present invention to provide a method for etching mesa formation of a laser diode, which can improve the performance of the device and improve the performance of the device to obtain good lasing characteristics.
상기 목적을 달성하기 위하여 본 발명은, n+-InP 기판, n-InP 에피텍셜층, 불순물이 주입되지 않은 InGaAsP 활성층, p-InP 에피텍셜층, SiO2층이 차례로 성장되어 있는 레이저 다이오드의 메사 형성 식각방법에 있어서, 상기 SiO2층을 마스크로 사용하여 InP층 선택 식각제인 HCI : H3PO4식각제로 상기 p-InP 에피텍셜층을 식각하는 제 1 단계 및 상기 제 1 단계 후에 InP 선택 식각제인 HCI : H3PO4식각제로 상기 n-InP 에피텍셜층을 식각하는 제 2 단계를 포함하여 이루어지는 것을 특징으로 한다.In order to achieve the above object, the present invention provides a mesa of a laser diode in which an n + -InP substrate, an n-InP epitaxial layer, an InGaAsP active layer in which impurities are not implanted, a p-InP epitaxial layer, and a SiO 2 layer are sequentially grown. In the forming etching method, the first step of etching the p-InP epitaxial layer with the HCI: H 3 PO 4 etchant which is an InP layer selective etchant using the SiO 2 layer as a mask and the InP selective etching after the first step Jane HCI: H 3 PO 4 It characterized by comprising a second step of etching the n-InP epitaxial layer with an etchant.
이하, 첨부된 도면 제 2 도를 참조하여 본 발명을 상세히 설명하면, 도면에서 9는 n+-InP 기판, 10은 n-InP 에피텍셜층, 11은 InGaAsP 활성층, 12는 p-InP 에피텍셜층, 13은 SiO2또는 Si3N4마스크층, 21는 n-InGaAsP 도파관층을 각각 나타낸다.Hereinafter, the present invention will be described in detail with reference to FIG. 2, where n is an n + -InP substrate, 10 is an n-InP epitaxial layer, 11 is an InGaAsP active layer, and 12 is a p-InP epitaxial layer. And 13 are SiO 2 or Si 3 N 4 mask layers, and 21 are n-InGaAsP waveguide layers, respectively.
먼저, 제 2 도(a)에서와 같이 n+-InP 기판(9)에 n-InP 에피텍셜층(10)을 성장하고, n-InGaAsP 도파관층(21)(도파관이 없는 LD 구조에 있어서는 성장하지 않음)을 성장한 다음, 불순물이 주입되지 않은 InGaAsP 활성층(11) 및 p-InP 에피텍셜층(12)을 차례로 성장한다. 여기서, 식각 마스크를 위하여 SiO2또는 Si3N4층(13)을 증착한다.First, as shown in FIG. 2A, an n-InP epitaxial layer 10 is grown on an n + -InP substrate 9, and an n-InGaAsP waveguide layer 21 (in an LD structure without a waveguide) is grown. And the InGaAsP active layer 11 and the p-InP epitaxial layer 12 which are not implanted with impurities are sequentially grown. Here, a SiO 2 or Si 3 N 4 layer 13 is deposited for the etch mask.
이어서, 제 2 도(b)에서는 상기 제 2 도(a)의 SiO2또는 Si3N4(13)을 마스크로 사용하여 식각 표면이 깨끗하고 언더컷(under cut) 식각이 적은 InP층 선택 식각제인 HCl : H3PO4(1 : 2) 식각제로 p-InP 에피텍셜층(12)을 식각한다.Next, FIG. 2 (b) In the second diagram (a) of SiO 2 or Si 3 N 4 (13) for use as a mask, etching the surface is clean, the undercut (under cut) etching is less InP layer selected etching agent The p-InP epitaxial layer 12 is etched with HCl: H 3 PO 4 (1: 2) etchant.
그리고 제 2 도(c)에서는 InGaAsp/InP 비선택 식각제인 HCl : H2O2: CH3COOH(3 : 1 : 36) 또는 0.2% 브롬-메탄올 식각제로 InGaAsP 활성층(11)과 InGaAsP 도파관층(21)을 식각한다.In FIG. 2 (c), the InGaAsP active layer 11 and the InGaAsP waveguide layer (HCl: H 2 O 2 : CH 3 COOH (3: 1: 36) or 0.2% bromine-methanol etchant as an InGaAsp / InP non-selective etchant) 21).
끝으로 제 2 도(d)에서는 InP 선택 식각제인 HCl : H3PO4(1 : 2) 식각제로 상기 n-InP 에피텍셜층(10)을 상기 본 발명의 식각제의 작용상태를 살펴보면 다음과 같다.Finally, in FIG. 2 (d), the n-InP epitaxial layer 10 is used as an InP selective etchant, HCl: H 3 PO 4 (1: 2) etchant. same.
상기 InP층 선택 식각제인 HCl : H3PO4(1 : 2)의 식각제는 식각 마스크로 SiO2또는 Si3N4층을 사용할 경우 언더컷이 적고, 식각 표면이 깨끗하며, 식각률이 안정되어 신뢰성 및 재현 우수성을 가져온다. 그리고 상기 InGaAsP층 선택 식각제인 H2SO4: H2O2: H2O(3 : 1: 1 또는 1 : 1: 4)의 식각제는 식각 마스크로 SiO2또는 Si3N4를 사용할 경우 언더컷이 적고 식각 특성이 양호하여 식각 제어성 및 신뢰성을 가져오며, 또한 상기 InGaAsP/InP층 비선택 식각제인 HCl : H2O2: CH3COOH 또는 0.2% 브롬-메탄올 식각제도 양호한 식각 특성을 얻을 수 있게 한다.The etchant of HCl: H 3 PO 4 (1: 2), which is an InP layer selective etchant, has less undercut when the SiO 2 or Si 3 N 4 layer is used as an etching mask, the etching surface is clean, and the etching rate is stable. And reproduction excellence. In addition, the etchant of H 2 SO 4 : H 2 O 2 : H 2 O (3: 1: 1 or 1: 1: 4), which is the InGaAsP layer selective etchant, uses SiO 2 or Si 3 N 4 as an etching mask. Less undercut and good etching characteristics result in etching controllability and reliability, and also the HCl: H 2 O 2 : CH 3 COOH or 0.2% bromine-methanol etchant, the InGaAsP / InP layer non-selective etchant, To be able.
상기와 같이 이루어지는 본 발명은 식각 특성이 양호한 식각제를 선택적으로 사용함으로써 식각 마스크의 언더컷 현상을 최소화할 수 있으며, 활성층 폭의 조절이 우수하여 레이징의 특성을 향상시킬 수 있고, 식각 재현성, 식각 제어성, 식각 표면 특성을 향상시킬 수 있는 효과가 있다.The present invention made as described above can minimize the undercut phenomenon of the etching mask by selectively using an etching agent having good etching characteristics, and can improve the characteristics of the rasing by excellent control of the active layer width, etching reproducibility, etching There is an effect that can improve the controllability, etching surface properties.
Claims (7)
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| KR1019920026881A KR960003752B1 (en) | 1992-12-30 | 1992-12-30 | Etching method of mesa-structure for laser diode |
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| Country | Link |
|---|---|
| KR (1) | KR960003752B1 (en) |
-
1992
- 1992-12-30 KR KR1019920026881A patent/KR960003752B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR940015679A (en) | 1994-07-21 |
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