JP2001039799A - Observation method of surface defect of nitride compound semiconductor - Google Patents
Observation method of surface defect of nitride compound semiconductorInfo
- Publication number
- JP2001039799A JP2001039799A JP11210146A JP21014699A JP2001039799A JP 2001039799 A JP2001039799 A JP 2001039799A JP 11210146 A JP11210146 A JP 11210146A JP 21014699 A JP21014699 A JP 21014699A JP 2001039799 A JP2001039799 A JP 2001039799A
- Authority
- JP
- Japan
- Prior art keywords
- koh
- compound semiconductor
- etch pits
- sample
- nitride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
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- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する分野】本発明はナイトライド系化合物半
導体の表面欠陥観察法に関するものである。[0001] 1. Field of the Invention [0002] The present invention relates to a method for observing surface defects of a nitride compound semiconductor.
【０００２】[0002]
【従来の技術】ナイトライド系化合物半導体、主にＧａ
Ｎは一般に格子不整合の大きいサファイア基板上に結晶
成長されるため、大きな転位密度（−１０8ｃｍ-3）を
有する。転位の存在はデバイス特性の劣化、寿命の短縮
を引き起こすと認識されている。よって、デバイス作製
前の基板選別過程において、転位の評価は重要である。
従来、簡易的な転位の観察法として、ＩＩＩ−Ｖ化合物
半導体では非等方ケミカルエッチにより、半導体表面に
エッチピットを形成し、表面欠陥を観察する手法が取ら
れてきた。ナイトライド系化合物半導体でも高温でＫＯ
Ｈ、Ｈ3ＰＯ4等の溶液を用いるとエッチピットが形成出
来ることが報告されている。しかし、エッチピットの起
源については、表面欠陥との相関の有無を含めて、明確
にされていない。また、大小様々な（＞０．１μｍ）エ
ッチピットの存在に適応するエッチング後の表面観察法
が提案されていない。小さなエッチピットに対して、金
属顕微鏡では空間分解能が足りず、平面、断面ＴＥＭで
は膜中の転位は良く観察されるが、表面の微少な窪みに
対してはコントラストがでないという問題が生じる。ま
た、ＳＥＭ、ＴＥＭ等の電子顕微鏡を用いた手法では、
真空中観察、及び微細な試料加工工程を必要とする。2. Description of the Related Art A nitride compound semiconductor, mainly Ga
Since N is generally grown on a sapphire substrate having a large lattice mismatch, N has a large dislocation density (−10 8 cm −3 ). It is recognized that the presence of dislocations causes deterioration of device characteristics and shortening of life. Therefore, the evaluation of dislocations is important in the substrate sorting process before device fabrication.
Conventionally, as a simple method of observing dislocations, a method of observing surface defects by forming etch pits on the surface of a III-V compound semiconductor by anisotropic chemical etching has been adopted. KO at high temperature even with nitride compound semiconductor
It is reported that etch pits can be formed by using a solution such as H or H 3 PO 4 . However, the origin of the etch pit, including whether or not there is a correlation with a surface defect, has not been clarified. In addition, a method for observing the surface after etching, which adapts to the presence of etch pits of various sizes (> 0.1 μm) has not been proposed. For a small etch pit, the spatial resolution is not enough with a metallurgical microscope, and dislocations in the film are well observed with a planar or cross-sectional TEM, but there is a problem that contrast is not good with a fine pit on the surface. In the method using an electron microscope such as SEM and TEM,
It requires observation in vacuum and a fine sample processing step.
【０００３】[0003]
【発明が解決しようとする課題】本発明の目的は、簡単
なナイトライド系化合物半導体の表面欠陥観察法を提供
することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a simple method for observing a surface defect of a nitride compound semiconductor.
【０００４】[0004]
【課題を解決するための手段】上記課題を解決するた
め、本発明によるナイトライド系化合物半導体の表面欠
陥観察法は、ナイトライド系化合物半導体表面を高温で
ＫＯＨ融液で処理してエッチピットを形成したのち、酸
で表面に残留したＫＯＨを除去し、前記エッチピットを
原子間力顕微鏡で観察するを特徴とするものである。In order to solve the above-mentioned problems, a method for observing the surface defects of a nitride-based compound semiconductor according to the present invention comprises treating a nitride-based compound semiconductor surface with a KOH melt at a high temperature to remove etch pits. After formation, KOH remaining on the surface is removed with an acid, and the etch pit is observed with an atomic force microscope.
【０００５】本発明によれば、ＫＯＨ系融液でナイトラ
イド系化合物半導体表面を所定条件で処理し、エッチピ
ットを形成した後、前記ＫＯＨを酸で除去するため、前
記エッチピットを原子間顕微鏡で観察することが可能に
なり、容易に表面欠陥を観察できる。According to the present invention, the surface of a nitride-based compound semiconductor is treated with a KOH-based melt under predetermined conditions to form an etch pit, and then the KOH is removed with an acid. And surface defects can be easily observed.
【０００６】本発明をさらに詳しく説明すると、本発明
においてはナイトライド系化合物半導体表面をＫＯＨ融
液に浸してエッチピットを形成する。前記ＫＯＨ融液
は、好ましくは３００℃以上、３６０℃以下であるのが
よい。３００℃未満であると、エッチピットが形成しな
い恐れがあり、一方３６０℃を超えるとナイトライド系
化合物半導体を溶解する恐れがあり、またＫＯＨ融液を
それ以上の温度にすることは困難であるからである。The present invention will be described in more detail. In the present invention, an etch pit is formed by immersing a nitride compound semiconductor surface in a KOH melt. The temperature of the KOH melt is preferably 300 ° C. or more and 360 ° C. or less. If the temperature is lower than 300 ° C., etch pits may not be formed. On the other hand, if the temperature exceeds 360 ° C., the nitride-based compound semiconductor may be dissolved. Because.
【０００７】このＫＯＨ融液に浸漬する時間は１０分未
満であるのがよい。１０分以上であると、ナイトライド
系化合物半導体を溶解する恐れが生じるからである。The immersion time in the KOH melt is preferably less than 10 minutes. If the time is longer than 10 minutes, the nitride-based compound semiconductor may be dissolved.
【０００８】本発明においては、上述の様な条件でエッ
チピットを形成した後、酸でＫＯＨ融液を中和して除去
する。図１は後処理の効果を説明した概念図である。Ｋ
ＯＨ融液でのエッチング後は試料の温度が下がり、試料
１の表面にＫＯＨ層２が残留、付着する。そのため、エ
ッチピット３の観察が行えない。酸による洗浄でＫＯＨ
が中和し除去され、良好にエッチピットの観測が行える
ようになる。In the present invention, after the etch pits are formed under the above conditions, the KOH melt is neutralized and removed with an acid. FIG. 1 is a conceptual diagram illustrating the effect of post-processing. K
After the etching with the OH melt, the temperature of the sample decreases, and the KOH layer 2 remains and adheres to the surface of the sample 1. Therefore, observation of the etch pit 3 cannot be performed. KOH by acid washing
Is neutralized and removed, so that etch pits can be observed well.
【０００９】前記ナイトライド系化合物半導体は、酸に
侵されことはないので、基本的にいかなる酸も使用可能
である。たとえば塩酸、硫酸、フッ酸などの無機酸、あ
るいは有機酸などを有効に使用できる。Since the nitride-based compound semiconductor is not attacked by an acid, basically any acid can be used. For example, inorganic acids such as hydrochloric acid, sulfuric acid and hydrofluoric acid, or organic acids can be effectively used.
【００１０】以下実施例を説明する。An embodiment will be described below.
【００１１】[0011]
【実施例】１）エッチング：ナイトライド系化合物半導
体（ＧａＮ）を熱したＫＯＨ融液に浸し（３３０℃，１
分間）、表面欠陥近傍を選択的にエッチングし、エッチ
ピットを形成する。EXAMPLES 1) Etching: A nitride-based compound semiconductor (GaN) is immersed in a heated KOH melt (at 330 ° C., 1 ° C.).
Minute), the vicinity of the surface defect is selectively etched to form an etch pit.
【００１２】２）後処理：試料をＫＯＨ融液から取り出
し、塩酸に浸し中和により表面に残留したＫＯＨを取り
除いた。2) Post-treatment: The sample was taken out of the KOH melt, immersed in hydrochloric acid and neutralized to remove KOH remaining on the surface.
【００１３】図２は３３０℃、１分間ＫＯＨ融液がＧａ
Ｎ表面の転位近傍を選択的にエッチングすることを確認
した例である。図２において黒点がエッチピットであ
る。図３は２００℃、２０分間のＫＯＨエッチングした
試料であり、エッチピットは形成されていない。また、
３３０℃、１０分間では厚さ２μｍのＧａＮ層がすべて
溶解した。FIG. 2 shows that the KOH melt is changed to Ga at 330 ° C. for one minute.
This is an example in which it has been confirmed that the vicinity of dislocations on the N surface is selectively etched. In FIG. 2, black dots are etch pits. FIG. 3 shows a sample subjected to KOH etching at 200 ° C. for 20 minutes, in which no etch pit is formed. Also,
At 330 ° C. for 10 minutes, the entire 2 μm-thick GaN layer was dissolved.
【００１４】前記図２、図３は１０．１４７×１０．１
４７μｍの範囲の処理を行った試料のＡＦＭ写真であ
る。また、下のスリットは高さを濃淡で示すものであ
り、最も濃い部分を０として、最も薄い部分の高さが１
７．３２１ｎｍ（図２）、４．３００１ｎｍ（図３）で
あることを示している。FIGS. 2 and 3 show 10.147 × 10.1.
It is an AFM photograph of the sample which performed processing of the range of 47 micrometers. The lower slit shows the height in shades, with the darkest part being 0 and the thinnest part being 1 in height.
7.321 nm (FIG. 2) and 4.3001 nm (FIG. 3).
【００１５】前記試料（図２）を用いて表面欠陥の二次
元的観察を原子間顕微鏡で行ったところ良好に表面の欠
陥が観察可能であった。When a two-dimensional observation of surface defects was performed by an atomic force microscope using the sample (FIG. 2), surface defects could be observed well.
【００１６】[0016]
【発明の効果】以上述べたように、本発明を用いれば、
簡単にナイトライド系化合物半導体の表面欠陥の二次元
観察を実現できる。As described above, according to the present invention,
Two-dimensional observation of surface defects of a nitride-based compound semiconductor can be easily realized.
【図面の簡単な説明】[Brief description of the drawings]
【図１】後処理の効果の説明するための説明図。FIG. 1 is an explanatory diagram for explaining an effect of post-processing.
【図２】ナイトライド系化合物半導体をＫＯＨエッチン
グ（３３０℃、１分間）した試料表面のＡＦＭ写真。FIG. 2 is an AFM photograph of a sample surface obtained by etching a nitride-based compound semiconductor by KOH (at 330 ° C. for 1 minute).
【図３】ナイトライド系化合物半導体をＫＯＨエッチン
グ（２００℃、２０分間）した試料表面のＡＦＭ写真。FIG. 3 is an AFM photograph of a sample surface obtained by performing a KOH etching (200 ° C., 20 minutes) on a nitride-based compound semiconductor.
１ 試料 ２ ＫＯＨ層 ３ エッチピット 1 sample 2 KOH layer 3 etch pit
Claims (3)
でＫＯＨ融液で処理してエッチピットを形成したのち、
酸で表面に残留したＫＯＨを除去し、前記エッチピット
を原子間力顕微鏡で観察するを特徴とするナイトライド
系化合物半導体の表面欠陥観察法。1. After the surface of a nitride-based compound semiconductor is treated with a KOH melt at a high temperature to form an etch pit,
A method for observing a surface defect of a nitride compound semiconductor, wherein KOH remaining on the surface is removed with an acid, and the etch pit is observed with an atomic force microscope.
記エッチングの時間は１０分未満であることを特徴とす
る請求項１に記載のナイトライド系化合物半導体の表面
欠陥観察法。2. The method according to claim 1, wherein the KOH melt is at least 300 ° C. and the etching time is less than 10 minutes.
ッチングの時間は１分であることを特徴とする請求項２
に記載のナイトライド系化合物半導体の表面欠陥観察
法。3. The method of claim 2, wherein the KOH melt has a temperature of 330 ° C. and the etching time is 1 minute.
2. The method for observing surface defects of a nitride-based compound semiconductor according to item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11210146A JP2001039799A (en) | 1999-07-26 | 1999-07-26 | Observation method of surface defect of nitride compound semiconductor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11210146A JP2001039799A (en) | 1999-07-26 | 1999-07-26 | Observation method of surface defect of nitride compound semiconductor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001039799A true JP2001039799A (en) | 2001-02-13 |
Family
ID=16584539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11210146A Pending JP2001039799A (en) | 1999-07-26 | 1999-07-26 | Observation method of surface defect of nitride compound semiconductor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001039799A (en) |
-
1999
- 1999-07-26 JP JP11210146A patent/JP2001039799A/en active Pending
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