JPH071781B2 - Photocapacitance measurement method with constant capacitance - Google Patents
Photocapacitance measurement method with constant capacitanceInfo
- Publication number
- JPH071781B2 JPH071781B2 JP58231922A JP23192283A JPH071781B2 JP H071781 B2 JPH071781 B2 JP H071781B2 JP 58231922 A JP58231922 A JP 58231922A JP 23192283 A JP23192283 A JP 23192283A JP H071781 B2 JPH071781 B2 JP H071781B2
- Authority
- JP
- Japan
- Prior art keywords
- constant
- depletion layer
- capacitance
- photocapacitance
- bias voltage
- 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.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/76—Making of isolation regions between components
Description
【発明の詳細な説明】 本願発明は、半導体中の深い準位を測定する方法に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring a deep level in a semiconductor.
従来、半導体中の深い準位に対する測定法として、PC
（Photoconductivity）、TSC（Thermally Stimulated C
urrent）、TSCAP（Thermally Stimulated Capacitanc
e）、高温でのホール効果、光ホール効果、PL（Photolu
minescence）、Junction Capacitance、Junction Curre
nt、Lifetime、IR吸収、ESR（Eletron Spin Resonanc
e）等、種々あるが、次に挙げるフォトキャパシタンス
法（Photocapacitance以下PHCAPという。）、DLTS法（D
eep Level Transient Spectroscopy以下DLTSという。）
は、実際のデバイスに近いｐ−ｎ接合、ショットキ接合
の形で極めて極微量の深い準位の密度が検出できる。Conventionally, PC has been used as a measurement method for deep levels in semiconductors.
(Photoconductivity), TSC (Thermally Stimulated C
urrent), TSCAP (Thermally Stimulated Capacitanc
e), Hall effect at high temperature, optical Hall effect, PL (Photolu
minescence), Junction Capacitance, Junction Curre
nt, Lifetime, IR absorption, ESR (Eletron Spin Resonanc
There are various types such as e), but the following photocapacitance method (Photocapacitance hereafter PHCAP), DLTS method (D
DLTS is referred to as eep Level Transient Spectroscopy. )
Can detect a very small amount of deep level density in the form of a pn junction or a Schottky junction close to an actual device.
更に、DLTSは、深い準位に獲えられた電子を熱励起する
ことにより、そのエミッションレイトの温度依存性から
深い準位の活性化エネルギーを求めるところから、測定
温度を77〜400Kとすると概算で、価電子帯、伝導帯から
約0.8eV程度の深い準位が測定されるのに対し、PHCAP
は、直接、分光された光を照射して励起するところか
ら、被測定物の半導体の禁制帯幅に近いところまで深い
準位の活性化ができ、DLTSでは困難な1.0eV以上の深い
準位の測定も可能である。DLTSで、0.8eV以上の活性化
エネルギーを有する深い準位の測定の為には、約400K以
上もの高温にする必要があり、このような高温では、pn
接合、ショットキーバリアダイオード等の特性の変化さ
らには、破壊を引き起してしまい測定不可能である。Furthermore, DLTS obtains the activation energy of the deep level from the temperature dependence of its emission rate by thermally exciting the electrons captured in the deep level, and it is estimated that the measured temperature is 77 to 400K. At about 0.8 eV deep level from the valence band and conduction band, the PHCAP
Is capable of activating deep levels directly from the point where it is excited by radiating dispersed light to the point near the forbidden band width of the semiconductor under test, and deep levels of 1.0 eV or higher, which are difficult for DLTS. Can also be measured. In DLTS, in order to measure a deep level having an activation energy of 0.8 eV or more, it is necessary to raise the temperature to about 400 K or more. At such a high temperature, pn
Changes in the characteristics of the junction, the Schottky barrier diode, etc., and further, destruction cause unmeasurable.
従来、PHCAPは、一定逆バイアスを印加し、単色光を照
射した時の空乏層容量の変化から深い準位の密度を求め
ていた。これをp+ｎ接合の場合を例にとって述べる。第
１図は、p+ｎ接合の空乏層近くのエネルギー図である。
空乏層中の深い準位を、冷暗所にて、順方向に微かなが
ら電圧を印加し深い準位に電子を捕獲させた後、逆バイ
アス電圧（Ｖ）を印加した時の状態である。この状態の
空乏層に、分光した単色光を照射して、深い準位に捕獲
された電子を励起すると、第２図（ａ）、（ｂ）のよう
に空乏層中の電荷分布状態が変化する。第２図（ａ）
は、逆バイアスの印加電圧を一定にしたままの時であ
り、第２図（ｂ）は、空乏層容量が一定になるように、
逆バイアスの印加電圧を変化させた場合である。第２図
（ａ）の逆バイアスの印加電圧が一定の場合は、空乏層
容量が変化し、空乏層の幅がＷからＷ′に変化する。第
２図（ｂ）の空乏層容量一定の場合は、逆バイアスの印
加電圧はＶからＶ′に変り、空乏層の幅はＷのまま変ら
ない。以上のように、逆バイアスの印加電圧を一定にし
て、光照射による空乏層容量の変化から深い準位の密度
を求める方法は、上述のように、接合容量の変化即ち、
空乏層の幅の変化が起こり、測定された深い準位の密度
が、接合部分からどこまでの距離の領域における値か、
測定前に明確に決定できないという欠点を有している。
従って、所定の空乏層領域内の深い準位の密度を求める
為には、フォトキャパシタンス測定時に空乏層の幅を一
定に保つ必要があり、その為には空乏層容量を一定に保
持つように外部からの印加電圧を制御することによっ
て、深い準位の密度を求める必要がある。これが、本願
発明の一定容量によるフォトキャパシタンス測定方法で
ある。Conventionally, PHCAP has been required to obtain a deep level density from a change in depletion layer capacitance when a constant reverse bias is applied and monochromatic light is irradiated. This will be described by taking the case of the p + n junction as an example. FIG. 1 is an energy diagram near the depletion layer of the p + n junction.
A state in which a reverse bias voltage (V) is applied after a voltage is applied to the deep level in the depletion layer in a cool dark place in the forward direction while slightly applying a voltage to trap electrons in the deep level. When the depletion layer in this state is irradiated with dispersed monochromatic light to excite electrons trapped in deep levels, the charge distribution state in the depletion layer changes as shown in FIGS. 2 (a) and 2 (b). To do. Fig. 2 (a)
Is when the reverse bias applied voltage is kept constant, and FIG. 2B shows that the depletion layer capacitance is constant.
This is a case where the reverse bias applied voltage is changed. When the reverse bias voltage applied in FIG. 2A is constant, the depletion layer capacitance changes and the width of the depletion layer changes from W to W '. When the capacity of the depletion layer in FIG. 2B is constant, the applied voltage of the reverse bias changes from V to V ′, and the width of the depletion layer remains W. As described above, the method of obtaining the density of the deep level from the change of the depletion layer capacitance by the light irradiation while keeping the reverse bias applied voltage constant is, as described above, the change of the junction capacitance, that is,
A change in the width of the depletion layer occurs, and the measured deep level density is the value in the region of the distance from the junction,
It has the drawback that it cannot be clearly determined before measurement.
Therefore, in order to obtain the density of the deep level in the predetermined depletion layer region, it is necessary to keep the width of the depletion layer constant at the time of measuring the photocapacitance. For that purpose, keep the depletion layer capacitance constant. It is necessary to obtain the deep level density by controlling the voltage applied from the outside. This is the method of measuring the photocapacitance by the constant capacitance of the present invention.
空乏層容量一定で、深い準位の密度を求める式を導出す
る。光照射前の空乏層容量（Cdark）は、外部からの印
加バイアス電圧をVdark、拡散電位をVdとすると、p+ｎ
接合又は、金属−ｎ形半導体接合の場合、空乏層内のド
ナー密度を一定とすると次式で与えられる。We derive an equation for obtaining the density of deep levels with a constant depletion layer capacity. The depletion layer capacitance (C dark ) before light irradiation is p + n when the bias voltage applied from the outside is V dark and the diffusion potential is Vd.
In the case of a junction or a metal-n-type semiconductor junction, if the donor density in the depletion layer is constant, it is given by the following equation.
ここで、ｑは電子の電荷量、Ａは接合面積、εSは半導
体結晶の誘電率、NDはｎ形半導体結晶中の浅いエネルギ
ー準位を有するドナーの密度、Vdはは拡散電位、Cdark
は、光照射前の容量、Vdarkは、光照射前に加えた外部
印加バイアス電圧である。 Here, q is the charge amount of electrons, A is the junction area, ε S is the dielectric constant of the semiconductor crystal, N D is the density of the donor having a shallow energy level in the n-type semiconductor crystal, Vd is the diffusion potential, and C dark
Is the capacitance before light irradiation, and V dark is the externally applied bias voltage applied before light irradiation.
次に、光を照射した後の接合容量（Cph）を、光照射前
の接合容量（Cdark）と同じになるように（Cph=Cdark）
外部印加バイアス電圧を調節し、この時の電圧をVphと
すると、接合容量は、次式で与えられる。Next, make the junction capacitance (C ph ) after light irradiation equal to the junction capacitance (C dark ) before light irradiation (C ph = C dark ).
When the externally applied bias voltage is adjusted and the voltage at this time is V ph , the junction capacitance is given by the following equation.
ここでNTは、空乏層中の深い準位の密度で一定であると
した。 Here, N T is assumed to be constant at a deep level density in the depletion layer.
（１）、（２）式より次式が導かれる。The following equation is derived from the equations (1) and (2).
（３）式より、一定容量法により、空乏層中の深い準位
の密度を、空乏層の幅を変えずに測定することが出来
る。この方法によって、例えば、第３図に示したよう
に、深い準位の密度NT（ｘ）が、接合部からの距離ｘに
対して、急峻に変化している場合、従来の逆バイアス印
加電圧を一定にする方法では、光を照射する前の空乏層
の幅がx2であり、光を照射した後の空乏層の幅は、x1に
変化してしまい、測定時に空乏層端の位置を決めること
ができない。従って、例えばイオン打ち込み法などで形
成した極めて薄い層等において、どの位置の深い準位の
測定を行なうかが極めて重要である場合は、本願発明の
ように一定容量法で測定を行なえば、測定時に、予め空
乏層端の位置を正確に決めることができ、その空乏層内
の深い準位の測定を行なうことができる。この方法を用
いて、実際にGaAlAs赤色発光ダイオードに応用した測定
例を第４図に示す。第４図に示した様に、グラフの横軸
の照射した光エネルギーｈν（eV）に対して、縦軸に光
を照射した後の接合容量を一定にする為に変化させたバ
イアス電圧変化ΔVphが測定されている。 From the equation (3), the density of deep levels in the depletion layer can be measured by the constant capacitance method without changing the width of the depletion layer. By this method, for example, as shown in FIG. 3, when the deep level density N T (x) changes abruptly with respect to the distance x from the junction, conventional reverse bias application is performed. In the method of keeping the voltage constant, the width of the depletion layer before irradiation with light is x 2 , and the width of the depletion layer after irradiation with light changes to x 1 and the depletion layer edge at the time of measurement is changed. I can't decide the position. Therefore, for example, in a very thin layer formed by the ion implantation method or the like, if it is extremely important at which position the deep level is to be measured, it is possible to perform the measurement by the constant capacitance method as in the present invention. Sometimes, the position of the edge of the depletion layer can be accurately determined in advance, and the deep level in the depletion layer can be measured. FIG. 4 shows an example of measurement actually applied to a GaAlAs red light emitting diode using this method. As shown in FIG. 4, with respect to the irradiated light energy hν (eV) on the horizontal axis of the graph, the bias voltage change ΔV was changed to keep the junction capacitance constant after the vertical axis was irradiated with light. ph is being measured.
以上が、一定容量によるフォトキャパシタンス測定方法
の詳細な説明であり、従来の一定電圧によフォトキャパ
シタンス測定方法との比較においてはるかに優れている
ことが理解される。本願発明による深い準位の測定法
は、今後ますます微細化の進む各種半導体デバイスの特
性向上等に寄与するところは極めて大であり、工業的価
値は極めて大きい。The above is a detailed description of the photocapacitance measuring method using a constant capacitance, and it is understood that it is far superior to the conventional photocapacitance measuring method using a constant voltage. The deep level measuring method according to the present invention greatly contributes to the improvement of the characteristics of various semiconductor devices which are further miniaturized in the future, and the industrial value is extremely large.
第１図は、p+ｎ接合に対して、冷暗所で、順方向に微か
ながら電圧を印加し深い準位に電子を捕獲させた後、逆
バイアス電圧を印加した時の空乏層のエネルギー図、第
２図（ａ）は、バイアス電圧を一定にして、光を照射し
た後の空乏層のエネルギー図、第２図（ｂ）は、接合容
量を一定にして、光を照射した後の空乏層のエネルギー
図、第３図は、接合部からの距離ｘに対して、深い準位
の密度NT（ｘ）の分布が、急峻に変化している場合の一
例を示すグラフ、第４図はGaAlAs発光ダイオードを用い
た一定容量によるフォトキャパシタンス測定の結果を示
すグラフである。FIG. 1 is an energy diagram of the depletion layer when a reverse bias voltage is applied after a slight voltage is applied to the p + n junction in a cool dark place in the forward direction to capture electrons in a deep level, FIG. 2 (a) is an energy diagram of the depletion layer after light irradiation with a constant bias voltage, and FIG. 2 (b) is a depletion layer after light irradiation with a constant junction capacitance. FIG. 3 is a graph showing an example of the case where the distribution of the deep level density N T (x) changes sharply with respect to the distance x from the junction, and FIG. 4 shows 5 is a graph showing the result of photocapacitance measurement with a constant capacity using a GaAlAs light emitting diode.
Claims (1)
電状態に応じて該試料ダイオードの接合容量を一定に保
つようにバイアス電圧を制御する一定容量によるフォト
キャパシタンス測定方法において、該試料ダイオードに
暗所で順バイアス電圧を加える工程と、暗所で該順バイ
アス電圧を加えた後、暗所で一定の接合容量を与える逆
バイアス電圧の飽和値１を得る工程と、該試料ダイオー
ドの空乏層中に単色光を照射し深い準位に捕獲された荷
電を励起する工程と、該単色光を照射した後の逆バイア
ス電圧の飽和値２を得る工程と、該飽和値２と該飽和値
１の差分を得る工程を有することを特徴とする一定容量
によるフォトキャパシタンス測定方法。1. A method for measuring a photocapacitance by a constant capacitance, wherein a bias voltage is controlled so as to keep a junction capacitance of the sample diode constant according to a charge state of a deep level in a depletion layer of the sample diode. In the dark, applying a forward bias voltage in the dark, applying the forward bias voltage in the dark, and then obtaining a saturation value 1 of the reverse bias voltage that gives a constant junction capacitance in the dark, and depleting the sample diode. Irradiating a layer with monochromatic light to excite charges trapped in deep levels; obtaining a saturation value 2 of the reverse bias voltage after irradiating the monochromatic light; the saturation value 2 and the saturation value A method for measuring a photocapacitance by a constant capacitance, comprising a step of obtaining a difference of 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58231922A JPH071781B2 (en) | 1983-12-07 | 1983-12-07 | Photocapacitance measurement method with constant capacitance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58231922A JPH071781B2 (en) | 1983-12-07 | 1983-12-07 | Photocapacitance measurement method with constant capacitance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60123038A JPS60123038A (en) | 1985-07-01 |
| JPH071781B2 true JPH071781B2 (en) | 1995-01-11 |
Family
ID=16931159
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58231922A Expired - Lifetime JPH071781B2 (en) | 1983-12-07 | 1983-12-07 | Photocapacitance measurement method with constant capacitance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH071781B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0693476B2 (en) * | 1986-11-11 | 1994-11-16 | 財団法人半導体研究振興会 | Crystal defect evaluation apparatus and evaluation method by constant volume method |
| JPS63140544A (en) * | 1986-12-01 | 1988-06-13 | Semiconductor Res Found | Photocapacitance measuring equipment by constant capacity method and measuring method |
| JPH01166533A (en) * | 1987-12-22 | 1989-06-30 | Semiconductor Res Found | Device for measurement of photocapacitance |
| WO1991001543A1 (en) * | 1989-07-19 | 1991-02-07 | Bell Communications Research, Inc. | Light-pen system for projected images |
| JP4774723B2 (en) * | 2004-11-17 | 2011-09-14 | カシオ計算機株式会社 | Projection apparatus, instruction image erasing method, and program |
| CN114216939B (en) * | 2021-12-14 | 2024-01-30 | 浙江大学杭州国际科创中心 | Silicon carbide surface defect state energy distribution measuring method, system and storage medium |
-
1983
- 1983-12-07 JP JP58231922A patent/JPH071781B2/en not_active Expired - Lifetime
Non-Patent Citations (2)
| Title |
|---|
| Ｊ．Ａｐｐｌ．Ｐｈｙｓ．５２（５）Ｍａｙ１９８１Ｐ．３４０５〜３４１２ |
| Ｊ．Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ，ｖｏｌ．２３Ｎｏ．３１Ａｕｇ．１９７３Ｐ．１５０ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60123038A (en) | 1985-07-01 |
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