JPS6213619B2 - - Google Patents
Info
- Publication number
- JPS6213619B2 JPS6213619B2 JP13841978A JP13841978A JPS6213619B2 JP S6213619 B2 JPS6213619 B2 JP S6213619B2 JP 13841978 A JP13841978 A JP 13841978A JP 13841978 A JP13841978 A JP 13841978A JP S6213619 B2 JPS6213619 B2 JP S6213619B2
- Authority
- JP
- Japan
- Prior art keywords
- insulator
- oxide film
- charge trapping
- measuring
- current
- 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
Links
- 238000000034 method Methods 0.000 claims description 13
- 238000010894 electron beam technology Methods 0.000 claims description 12
- 230000005484 gravity Effects 0.000 claims description 7
- 239000012212 insulator Substances 0.000 claims description 7
- 239000004065 semiconductor Substances 0.000 claims description 3
- 230000005865 ionizing radiation Effects 0.000 claims description 2
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 239000004020 conductor Substances 0.000 claims 2
- 239000002800 charge carrier Substances 0.000 claims 1
- 239000010408 film Substances 0.000 description 21
- 229910052710 silicon Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000000969 carrier Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000000691 measurement method Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Description
【発明の詳細な説明】
この発明は、金属―酸化膜―シリコン
（MOS）構造におけるシリコン酸化膜に代表され
るごとき導体電極と半導体にはさまれた絶縁体中
の電荷捕獲中心（以下トラツプと称する）の特性
測定方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION This invention focuses on charge trapping centers (hereinafter referred to as traps) in an insulator sandwiched between a conductive electrode and a semiconductor, such as a silicon oxide film in a metal-oxide-silicon (MOS) structure. The present invention relates to a method for measuring the characteristics of
集積回路の高密度化がLSIから超LSIへと進展
するにつれ、それに使用されるMOSトランジス
タのチヤネル長も短縮されつつあるが、それに伴
いソース・ドレイン電界が強くなるためにチヤネ
ル中の電荷担体（以下キヤリヤと称する）が高エ
ネルギーを得て衝突電離の確率が増大する。この
衝突電離により増殖したキヤリヤがチヤネル表面
近傍のシリコン酸化膜中に注入されトラツプに捕
獲されると、固定電荷としてMOSトランジスタ
のしきい値電圧の変動をきたし、MOS・LSIおよ
び超LSIの不安定性の要因となる。このため、シ
リコン酸化膜中における前記トラツプの分布その
他の諸特性を知ることが工業上重要な測定、評価
方法となつている。 As the density of integrated circuits progresses from LSI to VLSI, the channel length of the MOS transistors used in these circuits is also becoming shorter. (hereinafter referred to as carrier) obtains high energy and the probability of impact ionization increases. When carriers multiplied by this impact ionization are injected into the silicon oxide film near the channel surface and captured in a trap, they act as fixed charges and cause fluctuations in the threshold voltage of MOS transistors, causing instability in MOS/LSI and VLSI. becomes a factor. Therefore, knowing the distribution and other characteristics of the traps in the silicon oxide film has become an industrially important measurement and evaluation method.
トラツプの分布測定法として従来用いられてい
る方法は、４〜5eVの光子エネルギーの光を照射
してシリコン側およびゲート電極側からキヤリヤ
を注入しながら電流―電圧特性を測定し、電荷捕
獲を行わせる前後での電流―電圧特性の電圧軸に
沿つての移動量から求める方法（photoI―Ｖ法）
があるが、この場合前記の照射光が透過できるよ
うな半透明ゲート電極を設ける必要がある。 The method conventionally used to measure the trap distribution is to irradiate light with a photon energy of 4 to 5 eV, measure the current-voltage characteristics while injecting carriers from the silicon side and the gate electrode side, and capture the charge. A method of determining the current-voltage characteristics from the amount of movement along the voltage axis before and after the change (photoI-V method)
However, in this case, it is necessary to provide a semi-transparent gate electrode through which the irradiation light can be transmitted.
この発明はこのような従来法の欠点を取除くた
めになされたもので、通常のMOSダイオードを
用いてトラツプの面密度および厚さ方向分布の重
心の測定を可能とするものである。以下第１図、
および第２図に従つてこの発明を説明する。 The present invention has been made to eliminate these drawbacks of the conventional method, and makes it possible to measure the areal density of traps and the center of gravity of the distribution in the thickness direction using ordinary MOS diodes. Figure 1 below,
This invention will be explained with reference to FIG.
第１図はこの発明の一実施例を示すトラツプの
面密度および厚さ方向の重心を測定する場合の回
路例であつて、MOSダイオード１のゲートとな
る金属電極１ｃにこの金属電極１ｃを透過して酸
化膜１ｂの表面からわずかに入つたところまで達
する程度のエネルギーをもつた電子ビーム２を照
射して、酸化膜１ｂの表面近傍のみに電子―正孔
対を発生せしめ、同時に金属電極１ｃに直流電源
３により正および負のゲート電圧Ｖgを加えて、
電圧計４と電流計５により電流―電圧特性を測定
する。測定された電流（）―電圧（Ｖg）特性
は、例えば、第２図の曲線６ａおよび６ｂのごと
くになる。 FIG. 1 shows an example of a circuit for measuring the areal density and center of gravity in the thickness direction of a trap according to an embodiment of the present invention. The electron beam 2 is irradiated with enough energy to reach a point just below the surface of the oxide film 1b, generating electron-hole pairs only near the surface of the oxide film 1b, and at the same time, the metal electrode 1c is By applying positive and negative gate voltages V g from the DC power supply 3 to
Current-voltage characteristics are measured using a voltmeter 4 and an ammeter 5. The measured current ()-voltage (V g ) characteristics are, for example, curves 6a and 6b in FIG.
次に酸化膜１ｂ中に電子または正孔を注入し、
トラツプに捕獲させる。これらのキヤリヤを注入
する方法としては、MOSダイオード１にパルス
電圧を加え、シリコン基板１ａ中の少数キヤリヤ
を酸化膜１ｂ中になだれ注入する方法、あるいは
２〜5eVの光子エネルギーの光を照射し、内部光
電子放出によつて金属電極１ｃもしくはシリコン
基板１ａから酸化膜１ｂ中にキヤリヤを注入する
方法、あるいは10eV以上の光子エネルギーの光
もしくは電離放射線を照射して酸化膜１ｂの表面
に電子および正孔を発生させ、直流電界によつて
これらのうちの一方を酸化膜１ｂ内部に到達させ
てトラツプに捕獲させる方法等がある。トラツプ
に電荷が捕獲された後に再び前述の方法によつて
電子ビーム照射下での電流―電圧特性を測定する
と、グラフは第２図の曲線７ａ，７ｂのごとく６
ａ，６ｂを平行移動させたものになる。このグラ
フからトラツプの面密度と分布の重心を求める方
法は従来のphoto―IV法と同様であつて、例え
ば、デイー・アール・デイマリヤ（D.R.
DiMaria）の「ジヤーナル・オブ・アプライド・
フイジクス」（Journal of Applied Physics）誌
47巻９号（1976年９月）、4073ページから4077ペ
ージに所載の論文に記述されているが、曲線６ａ
から７ａへの移動量をΔV+g、曲線６ｂから７ｂ
への移動量をΔV-gとし、酸化膜の誘電率をε、
厚さをＬ、単位電荷（正値）をｇ、トラツプの面
密度をQt、トラツプの分布の重心の金属電極１
ｃと酸化膜１ｂとの界面から距離をとすると、
ΔV+gは、トラツプに注入された電荷に応じてシ
リコンの表面に誘起された電荷に対応しているか
ら、
ΔV+g＝−ｇｘ／εQt ……(a)
一方、ΔV-gは金属電極１ｃに誘起された電荷
に対応しているから、
ΔV-g＝−ｇ／ε（Ｌ−）Qt ……(b)
となる。したがつて、(a)，(b)両式より、未知の量
Qtおよびは、
Qt＝ε／ｇＬ（ΔV-g−ΔV+g） ……(1)
＝Ｌ〔１−（ΔV-g／ΔV+g）〕-1 ……(2)
によつて求められる。なお、第２図によりΔV+g
とΔV-gは必ず反対符号を持つから、第(2)式の
〔 〕内は常に１より大きく、０または負となる
ことはない。 Next, electrons or holes are injected into the oxide film 1b,
Have the trap capture it. As a method of injecting these carriers, a pulse voltage is applied to the MOS diode 1, and minority carriers in the silicon substrate 1a are injected into the oxide film 1b by avalanche, or by irradiation with light having a photon energy of 2 to 5 eV. A method in which carriers are injected into the oxide film 1b from the metal electrode 1c or the silicon substrate 1a by internal photoelectron emission, or electrons and holes are injected into the surface of the oxide film 1b by irradiating light or ionizing radiation with a photon energy of 10 eV or more. There is a method in which one of them is generated by a DC electric field and is caused to reach the inside of the oxide film 1b and to be captured in a trap. When the current-voltage characteristics under electron beam irradiation are measured again using the method described above after the charge is captured in the trap, the graph becomes 6 as shown by curves 7a and 7b in Figure 2.
This is obtained by moving a and 6b in parallel. The method of determining the areal density and center of gravity of the trap from this graph is the same as the conventional photo-IV method.
DiMaria)'s ``Journal of Applied
Journal of Applied Physics
As described in the paper published in Vol. 47, No. 9 (September 1976), pages 4073 to 4077, curve 6a
The amount of movement from to 7a is ΔV + g, and from curve 6b to 7b
The amount of movement to is ΔV - g, and the dielectric constant of the oxide film is ε,
The thickness is L, the unit charge (positive value) is g, the surface density of the trap is Qt, and the center of gravity of the trap distribution is metal electrode 1.
The distance from the interface between c and oxide film 1b is:
Since ΔV + g corresponds to the charge induced on the silicon surface according to the charge injected into the trap, ΔV + g=-gx/εQt... (a) On the other hand, ΔV - g is the metal electrode. Since it corresponds to the charge induced in 1c, ΔV - g=-g/ε(L-)Qt...(b). Therefore, from both equations (a) and (b), the unknown quantity
Qt and are determined by Qt=ε/gL(ΔV - g−ΔV + g)...(1) =L[1−(ΔV - g/ΔV + g)] -1 ...(2) . Furthermore, according to Figure 2, ΔV + g
Since and ΔV - g always have opposite signs, the value in brackets [ ] in equation (2) is always greater than 1 and is never 0 or negative.
この発明の実施に当つて注意すべき点は、電子
ビーム２の照射によつて酸化膜１ｂ中に新たに照
射損傷によるトラツプを生じないようにすること
である。そのためには電子ビーム２のエネルギー
を小さくすればよい。これは、電子ビーム２の酸
化膜１ｂ中への侵入距離をなるべく小さくしたい
という要請とも一致するものである。一例をあげ
れば、金属電極１ｃとして厚さ2500Åのアルミニ
ウムを用いた場合、電子ビーム２の加速電圧を
5KVとすると、電子ビーム２は酸化膜１ｂの表面
から44Åまでしか侵入せず、酸化膜１ｂの表面で
の電子ビーム２の平均エネルギーは50eVであ
る。このエネルギーは酸化膜１ｂ中に衝突電離に
よつて一組の電子・正孔対を定常的に作り出すの
に必要なエネルギー約27eVよりは大きく、か
つ、酸化膜１ｂ中に照射損傷を生じない程度に小
さい値である。なお、電子ビーム２の電流量は、
第１図の電流計５で測られる試料電流が10-12A
程度となるように設定するのが適当である。ま
た、この発明の測定法を行うための装置は、走査
形電子顕微鏡をわずかに改造するだけで実現可能
であり、照射電子ビームの寸法設定や試料上の測
定個所の選択、操作者による確認などは走査電子
顕微鏡の通常の機能を利用して行うことができ
る。 In carrying out the present invention, care must be taken to avoid creating new traps in the oxide film 1b due to irradiation damage due to the irradiation with the electron beam 2. For this purpose, the energy of the electron beam 2 may be reduced. This is consistent with the request to reduce the penetration distance of the electron beam 2 into the oxide film 1b as much as possible. For example, when aluminum with a thickness of 2500 Å is used as the metal electrode 1c, the acceleration voltage of the electron beam 2 is
When the voltage is 5 KV, the electron beam 2 penetrates only up to 44 Å from the surface of the oxide film 1b, and the average energy of the electron beam 2 at the surface of the oxide film 1b is 50 eV. This energy is larger than the energy of approximately 27 eV required to constantly create a pair of electrons and holes in the oxide film 1b by impact ionization, and is at a level that does not cause irradiation damage in the oxide film 1b. is a small value. Note that the amount of current of the electron beam 2 is
The sample current measured by ammeter 5 in Figure 1 is 10 -12 A.
It is appropriate to set it so that the Furthermore, the apparatus for carrying out the measurement method of this invention can be realized by only slightly modifying a scanning electron microscope, and it is possible to set the dimensions of the irradiated electron beam, select the measurement point on the sample, and confirm it by the operator. can be performed using the normal capabilities of a scanning electron microscope.
なお、この発明の測定方法は、シリコンとその
酸化膜に限らず、一般に半導体と絶縁性薄膜との
組合わせをもつた構造物に適用可能である。 Note that the measurement method of the present invention is applicable not only to silicon and its oxide film, but also to structures that generally have a combination of a semiconductor and an insulating thin film.
以上説明したようにこの発明の測定方法は、シ
リコン酸化膜等の絶縁体中のトラツプの諸特性に
関する従来の測定法の欠点を除くもので実用上有
用な価値を有するものである。 As explained above, the measuring method of the present invention eliminates the drawbacks of conventional measuring methods regarding various characteristics of traps in insulators such as silicon oxide films, and has practical value.
第１図および第２図はこの発明の一実施例を説
明するためのもので、第１図はトラツプの面密度
と分布の重心の測定の例を示す回路図、第２図は
電子ビーム照射下での電流―電圧特性曲線の概念
図である。
図中、１はMOSダイオード、１ａはシリコン
基板、１ｂは酸化膜、１ｃは金属電極、２は電子
ビーム、３は直流電源、４は電圧計、５は電流計
である。
Figures 1 and 2 are for explaining one embodiment of the present invention. Figure 1 is a circuit diagram showing an example of measuring the areal density of traps and the center of gravity of the distribution, and Figure 2 is a circuit diagram showing an example of measuring the center of gravity of trap area density and distribution. It is a conceptual diagram of the current-voltage characteristic curve below. In the figure, 1 is a MOS diode, 1a is a silicon substrate, 1b is an oxide film, 1c is a metal electrode, 2 is an electron beam, 3 is a DC power supply, 4 is a voltmeter, and 5 is an ammeter.
Claims (1)
電荷捕獲中心の面密度および表面垂直方向におけ
る空間的分布の重心位置を測定するに際し、前記
導体電極を通過しかつ前記絶縁体の表面近傍のみ
に侵入しうる程度のエネルギーをもつ電子線もし
くは電離放射線を照射して前記絶縁体中に電子お
よび正孔を発生せしめ、かつ前記照射を行いつつ
前記導体電極に正、負の直流電圧を印加して電流
―電圧特性を測定し、前記電荷捕獲中心に電荷坦
体の捕獲を行わしめる以前と以後との前記電流―
電圧特性の変動量を求め、この値から前記絶縁体
中における前記電荷捕獲中心の面密度および表面
垂直方向における空間的分布の重心位置を求める
ことを特徴とする絶縁体中の電荷捕獲中心の特性
測定方法。1. When measuring the areal density of charge trapping centers in an insulator sandwiched between a conductor electrode and a semiconductor and the centroid position of the spatial distribution in the direction perpendicular to the surface, generating electrons and holes in the insulator by irradiating it with an electron beam or ionizing radiation having enough energy to penetrate into the insulator, and applying positive and negative DC voltages to the conductor electrode while performing the irradiation. The current-voltage characteristics are measured by measuring the current-voltage characteristics before and after the charge carrier is captured at the charge trapping center.
Characteristics of charge trapping centers in an insulator, characterized in that the amount of variation in voltage characteristics is determined, and from this value, the areal density of the charge trapping centers in the insulator and the position of the center of gravity of the spatial distribution in the direction perpendicular to the surface are determined. Measuring method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13841978A JPS5565146A (en) | 1978-11-11 | 1978-11-11 | Characteristic measuring method for charge trap center in insulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13841978A JPS5565146A (en) | 1978-11-11 | 1978-11-11 | Characteristic measuring method for charge trap center in insulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5565146A JPS5565146A (en) | 1980-05-16 |
| JPS6213619B2 true JPS6213619B2 (en) | 1987-03-27 |
Family
ID=15221516
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13841978A Granted JPS5565146A (en) | 1978-11-11 | 1978-11-11 | Characteristic measuring method for charge trap center in insulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5565146A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023228338A1 (en) * | 2022-05-25 | 2023-11-30 | 株式会社日立ハイテク | Charged particle beam device, and measurement method |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102213693B (en) * | 2011-04-08 | 2012-10-10 | 北京大学 | Method for testing trap density of gate dielectric layer of semiconductor device without extending substrate |
| CN104198570B (en) * | 2014-09-10 | 2016-08-17 | 国家电网公司 | The apparatus and method of short circuit current decay calculation trap parameters are measured under reverse biased |
-
1978
- 1978-11-11 JP JP13841978A patent/JPS5565146A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023228338A1 (en) * | 2022-05-25 | 2023-11-30 | 株式会社日立ハイテク | Charged particle beam device, and measurement method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5565146A (en) | 1980-05-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Scarpa et al. | Ionizing radiation induced leakage current on ultra-thin gate oxides | |
| Weinberg et al. | High‐field transport in SiO2 on silicon induced by corona charging of the unmetallized surface | |
| US4812756A (en) | Contactless technique for semicondutor wafer testing | |
| Schwerin et al. | Investigation on the oxide field dependence of hole trapping and interface state generation in SiO2 layers using homogeneous nonavalanche injection of holes | |
| Wang et al. | Threshold voltage variations with temperature in MOS transistors | |
| Larcher et al. | A model of the stress induced leakage current in gate oxides | |
| Apte et al. | Constant current stress breakdown in ultrathin SiO2 films | |
| Egusa et al. | Carrier injection characteristics of the metal/organic junctions of organic thin‐film devices | |
| Aitken | Radiation-induced trapping centers in thin silicon dioxide films | |
| Ng et al. | Conductance-voltage measurements on germanium nanocrystal memory structures and effect of gate electric field coupling | |
| JPH0262948B2 (en) | ||
| Nakamae et al. | Measurements of deep penetration of low‐energy electrons into metal‐oxide‐semiconductor structure | |
| Lauer et al. | Measuring vacuum ultraviolet radiation-induced damage | |
| Munakata et al. | Observation of pn junctions with a flying-spot scanner using a chopped photon beam | |
| JPS6213619B2 (en) | ||
| Perkins et al. | Radiation effects in modified oxide insulators in MOS structures | |
| Hessel et al. | Escape depth of secondary electrons from electron-irradiated polymers | |
| US3688389A (en) | Insulated gate type field effect semiconductor device having narrow channel and method of fabricating same | |
| Candelori et al. | Thin oxide degradation after high-energy ion irradiation | |
| JPS6148656B2 (en) | ||
| Taylor et al. | Electron-beam-induced conduction in SiO2 thin films | |
| Srour et al. | Leakage current phenomena in irradiated SOS devices | |
| Bottoms et al. | Electron beam probe studies of semiconductor-insulator interfaces | |
| JP2609728B2 (en) | MIS interface evaluation method and apparatus | |
| Sixt et al. | Determination of cesium distributions in oxides of MOS structures by photoinjection studies |