JPS61200407A - Fourier transformation type infrared film thickness measuring apparatus - Google Patents
Fourier transformation type infrared film thickness measuring apparatusInfo
- Publication number
- JPS61200407A JPS61200407A JP3870785A JP3870785A JPS61200407A JP S61200407 A JPS61200407 A JP S61200407A JP 3870785 A JP3870785 A JP 3870785A JP 3870785 A JP3870785 A JP 3870785A JP S61200407 A JPS61200407 A JP S61200407A
- Authority
- JP
- Japan
- Prior art keywords
- infrared
- film thickness
- film
- spectrum
- interference
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明は、赤外線の反射干渉を利用して非接触Ｏ非破襄
で膜厚を測定する膜厚計に係り、特に赤外線の吸収が大
きい試料に好適な７一リエ変換方式赤外線膜厚計に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a film thickness meter that measures film thickness in a non-contact, non-destructive manner using reflection interference of infrared rays. The present invention relates to a 7-Lie transform type infrared film thickness meter suitable for.
従来、この種の装置は１９８２年発行の計測技術１０月
号Ｐ、１０５〜１０７における°半導体ウェハー膜Ｏ不
純物濃度測定装置“と題する論文において論じられてい
る。第３図はこの論文に記載されたフーリエ変換方式赤
外線膜厚計の概略を示した図である。図において、１は
光源、２は固定平面鏡、３は可動平面鏡、４は半透睨５
．７は平面鏡、６は試料、８は検出器、９はアパチ為ア
ーである。この様な光学系において薄膜を付けた試料を
測定した場合第４図の（ｔＬ）の様な信号が得られる。Conventionally, this type of device has been discussed in a paper entitled "Semiconductor wafer film O impurity concentration measuring device" in the October 1982 issue of Metrology Technology, P, 105-107. 1 is a diagram schematically showing a Fourier transform type infrared film thickness meter. In the diagram, 1 is a light source, 2 is a fixed plane mirror, 3 is a movable plane mirror, and 4 is a semi-transparent mirror 5.
．． 7 is a plane mirror, 6 is a sample, 8 is a detector, and 9 is an aperture. When a sample with a thin film is measured using such an optical system, a signal like (tL) in FIG. 4 is obtained.
中央の大きな信号（センターバースト）は可動平面鏡３
と固定平面鏡２の光路差がゼロの位置を示し、薄膜表面
で反射した光と薄膜を透過した後反射した光の干渉によ
うてセンタバーストを中心として対象な位置にナイドバ
ーストが現われる。このセンタバーストとサイドバース
トとの距離りは膜厚に比例し、次式で表わされる。The large signal in the center (center burst) is the movable plane mirror 3.
indicates the position where the optical path difference of the fixed plane mirror 2 is zero, and nid bursts appear at symmetrical positions around the center burst due to interference between the light reflected on the thin film surface and the light reflected after passing through the thin film. The distance between the center burst and the side burst is proportional to the film thickness, and is expressed by the following equation.
Ａｌ。Al.
４は定数１％は薄膜層の突気に対する赤外光の屈接率、
φは赤外光線の入射角度、＋ｔは膜厚である。この式に
よりＬを測定すれば膜厚ｄが求まる。膜厚が薄いほどＬ
は小さく、膜厚が２〜３μ囃下となるとサイドバースト
はセンターバーストの信号に埋もれて、測定が不可能と
なる。従りて、従来法では膜厚を付けてない試料（リフ
ァレンス）を予じめ測定して置き、次に薄膜を付は試料
を測定する。この両者のスペクトルの７−リエ変換スペ
クトルの差スペクトルにノイズ処理を行った後、さらに
７−リエ変換を行う。こうして得られたスペクトルは第
４図ｂ）の様に示される。このスペクトルはケプストラ
ムと呼ばれサイドバーストのみが強調される。従りて第
４図ｂ）の２Ｌ を測定する事により膜厚を求める事が
できる。4 is a constant, 1% is the refractive index of infrared light to the sudden air of the thin film layer,
φ is the incident angle of the infrared ray, and +t is the film thickness. By measuring L using this formula, the film thickness d can be determined. The thinner the film thickness, the L
is small, and when the film thickness falls below 2 to 3 μm, the side burst is buried in the signal of the center burst, making measurement impossible. Therefore, in the conventional method, a sample without a film thickness (reference) is measured in advance, and then the sample with a thin film is measured. After noise processing is performed on the difference spectrum between the 7-lier transformed spectra of both spectra, 7-lier transform is further performed. The spectrum thus obtained is shown in Figure 4b). This spectrum is called the cepstrum, and only the side bursts are emphasized. Therefore, the film thickness can be determined by measuring 2L in FIG. 4b).
しかし上記方法では試料の薄膜に吸収がある場合はサイ
ドバースト付近にも信号が現われ、％に膜厚が厚い場合
や、大きな吸収がある試料の場合サイドバーストが明瞭
に現われない欠点を有する。また上記方法は試料の測定
に合せて、薄膜のついてないリファレンス試料の測定が
必要な欠点を有する。試料によりてはリファレンス試料
の入手が困難な場合も有り問題である。However, the above method has the disadvantage that if the thin film of the sample has absorption, a signal will also appear near the sideburst, and if the film is relatively thick or the sample has large absorption, the sideburst will not appear clearly. Furthermore, the above method has the disadvantage that it is necessary to measure a reference sample without a thin film in addition to measuring the sample. Depending on the sample, it may be difficult to obtain a reference sample, which is a problem.
この発明は上述の問題点を解決するためになされたもの
で、薄ＭＫ大きな吸収がある試料でも高精度に膜厚を測
定できろ７一リエ変換方式赤外飯膜厚計を提供すること
を目的とする。This invention was made to solve the above-mentioned problems, and aims to provide an infrared film thickness meter using a 7-layer conversion method that can measure film thickness with high accuracy even in thin MK samples with large absorption. purpose.
赤外線の試料表面における入射角度と反射率の関係は第
５図の様に示される。入射角度１５度以上では垂直偏光
赤外光と水平偏光赤外光の反射率はほとんど同じである
が、入射角度１５度以上では前者の反射率の方が著しく
大きくなり、６０度附近では水偏光赤外光の反射率は０
となるこの反射率０の角度をブリウスター角という。The relationship between the angle of incidence of infrared rays on the sample surface and the reflectance is shown in FIG. At an incident angle of 15 degrees or more, the reflectance of vertically polarized infrared light and horizontally polarized infrared light is almost the same, but at an incident angle of 15 degrees or more, the reflectance of the former becomes significantly larger, and at around 60 degrees, the reflectance of the horizontally polarized infrared light is almost the same. The reflectance of infrared light is 0
The angle at which the reflectance is 0 is called the Brioster angle.
この角度で試料の反射赤外スペクトルを測定すれば第６
図の様になる。即ち垂直偏光測定では薄膜の膜厚による
干渉スペクトルが大きく重畳したものになり、水平偏光
測定では全くこれを含まないものである。従って両者の
差スペクトルを求めれば得られたスペクトルは膜厚によ
る干渉スペクトルだけになる。この差スペクトルをフー
リエ変換することにより膜厚に起因するサイドバースト
だけのノイズを含まないケプストラムが得られる。If the reflected infrared spectrum of the sample is measured at this angle, the 6th
It will look like the figure. That is, in vertical polarization measurement, interference spectra due to the thickness of the thin film are largely superimposed, whereas in horizontal polarization measurement, this is not included at all. Therefore, if the difference spectrum between the two is obtained, the obtained spectrum will be only the interference spectrum due to the film thickness. By Fourier transforming this difference spectrum, a cepstrum that does not include noise only due to side bursts due to film thickness can be obtained.
即ち一つの試料で垂直偏光測定と水平偏光測定を行５１
により測定が可能であり、従来方法の様にリファレンス
試料が必要ない。また上記方法で試料の吸収はキニンセ
ルされるので、得られたケプストラムにはノイズを含ま
ない。フーリエ変換の計算精度は赤外光の波長領域が狭
」
いほど高い、また一般に薄膜は２７００〜１８００ｃｍ
Ｋは吸収をもたない試料が多く、この領域の光だけ適過
する干渉フィルターを用いる事により、７−リエ変換の
計算精度だけでなく、Ｗｌ膜による吸収を考瞭する必要
がなくなる。In other words, vertical polarization measurement and horizontal polarization measurement are performed on one sample51.
It is possible to measure by using this method, and there is no need for a reference sample as in conventional methods. Furthermore, since the absorption of the sample is kinincelled in the above method, the obtained cepstrum does not contain noise. The calculation accuracy of Fourier transform is higher as the wavelength range of infrared light is narrower, and generally thin films are 2700 to 1800 cm.
Many samples of K do not have absorption, and by using an interference filter that allows only light in this region to pass through, it is not necessary to consider not only the calculation accuracy of the 7-Lier transform but also the absorption by the Wl film.
試料以外の光学系の補正は前記方法は優れており後記方
法と合せて行５事により前記目的が達成される。The above-mentioned method is excellent in correcting optical systems other than the sample, and the above-mentioned objective can be achieved by performing the following steps in combination with the method described below.
以下、本発明の一実施例１を第１図、及び第２図により
説明する。第１図において、９は赤外光光源クローバ、
１１は平面鏡、１２は可動鏡、１３は半透鏡、１４は干
渉フィルタ、１５は平面鏡、１６は赤外光偏光子、１７
は有機薄膜を付けた試料、１８は検出器（水銀、カドミ
ニクム、テルル検出器）、１９はアパチェア（絞り）で
ある。ここで用いた干渉フィルタは１８００〜２７００
ｃｍの赤外光を透過するフィルターである。第２図は
上記方法で赤外光の試料への入射角度６０度で測定した
結果を示す図である。Embodiment 1 of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, 9 is an infrared light source crowbar;
11 is a plane mirror, 12 is a movable mirror, 13 is a semi-transparent mirror, 14 is an interference filter, 15 is a plane mirror, 16 is an infrared light polarizer, 17
18 is a detector (mercury, cadminicum, tellurium detector), and 19 is an aperture (aperture). The interference filter used here is 1800-2700.
This is a filter that transmits infrared light of cm. FIG. 2 is a diagram showing the results of measurement using the above method at an incident angle of 60 degrees of infrared light on the sample.
ａ）は垂直偏光測定の結実現われた検出器の信号で、
ｂ）は平行偏光測定時の信号である。Ｃ）は両方のフー
リエ変換後の差スペクトルに若干の処理を行りた後７−
リエ変換した結果を示す図ケグスト２ムである。ノイズ
の少ないケプストラムで、これら膜厚を測定した結果５
．０１ ａｍでありだ。繰返し１０（ロ）測定したが、
全で５．Ｏｊ ａｍであまた。a) is the detector signal realized as a result of vertical polarization measurement,
b) is a signal during parallel polarization measurement. C) is 7- after performing some processing on the difference spectra after both Fourier transforms.
FIG. The results of measuring these film thicknesses using the cepstrum with less noise5
．． It's 01 am. I measured 10 times (b) repeatedly, but
5 in total. See you at Oj am.
次に本発明の実施例２について説明する。Next, a second embodiment of the present invention will be described.
２５％のカポ／粒子を含む約１０ｔｔｍＱ有機薄膜を付
つけた鉄板試料を実施例１の試料１８の代りに用い、１
４の干渉フィルタは４００〜１０００ｃｍ の赤外光
が透過するものを用いて、実施例１と同様の測定を５０
０回行い平均値を求めた。測定に掛った時間は約５分間
であった。このもののケプストラムから計算した結果塗
膜の厚さは１０．５μｍであワた。A steel plate sample with about 10 ttmQ organic thin film containing 25% capo/particle was used in place of sample 18 of Example 1;
The same measurement as in Example 1 was carried out at 50 cm using the interference filter 4 that transmits infrared light of 400 to 1000 cm.
The test was performed 0 times and the average value was determined. The time required for the measurement was approximately 5 minutes. As a result of calculation from the cepstrum of this product, the thickness of the coating film was 10.5 μm.
次に本発明の実施例３について説明する。Next, Example 3 of the present invention will be described.
実施例２と全（同じ試料を１４の干渉フィルタなして測
定を実施例１と同様の測定を１０００ 回行い平均値
を求めた。このもののケプストラムから計算した結果塗
膜の厚さは１０．４βｍであった。The same sample as in Example 2 was measured using 14 interference filters, and the same measurements as in Example 1 were performed 1,000 times to obtain the average value.As a result of calculation from the cepstrum of this sample, the thickness of the coating film was 10.4βm. Met.
以上説明したように、この発明に係るフーリエ変換方式
赤外線膜厚計は赤外線の吸収が大きい、例えば黒い色の
薄膜でも、高精度でその膜厚が測定可能である。As explained above, the Fourier transform type infrared film thickness meter according to the present invention can measure the film thickness with high precision even for a thin film that absorbs a large amount of infrared rays, for example, a black film.
第１図はこの発明の一実施例の７一リエ変換方式赤外線
膜厚計を示す構成図、第２図は同じく測定結果例を示す
線図、第３図は従来の７一リエ変換方式赤外線膜厚計を
示す図、第４図は従来法による測定結果例を示す図、第
５図は赤外光の試料表面における反射率と入射角度の関
係図、第６図ａ）は赤外光の入射角６０度の場合の垂直
偏光測定における赤外スペクトル図、ｈ）は平行偏光測
定における赤外スペクトル図である。
９・・・赤外光々源
１１・・・平面鏡
１２・・・可動鏡
１３・・・半透鏡
１４・・・干渉フィルター
１５・・・平面鏡
１６・・・赤外光偏光子
１７・・・試料
１８・・・検出器
１９・・・アバチエア−
代雇人弁理士小川 勝馬
第２図
第３図
第４図
（’ｌ） （ｂ）セーター
ハトストFig. 1 is a configuration diagram showing a 71-Lie transform type infrared film thickness meter according to an embodiment of the present invention, Fig. 2 is a diagram showing an example of measurement results, and Fig. 3 is a conventional 71-Lie conversion type infrared film thickness meter. Figure 4 shows an example of measurement results using a conventional method. Figure 5 shows the relationship between the reflectance of infrared light on the sample surface and the angle of incidence. Figure 6 a) shows the relationship between infrared light and the incident angle. h) is an infrared spectrum diagram in vertical polarization measurement when the incident angle is 60 degrees, and h) is an infrared spectrum diagram in parallel polarization measurement. 9... Infrared light source 11... Plane mirror 12... Movable mirror 13... Semi-transparent mirror 14... Interference filter 15... Plane mirror 16... Infrared light polarizer 17... Sample 18...Detector 19...Abachi Air - Patent Attorney Katsuma Ogawa Figure 2 Figure 3 Figure 4 ('l) (b) Sweater Hatst
Claims (1)
外光偏光子を具備することを特徴とするフーリエ変換方
式赤外線膜厚計1. A Fourier transform type infrared film thickness meter, which is equipped with an infrared light interference filter and an infrared light polarizer between the object to be measured and the light source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60038707A JPH0721405B2 (en) | 1985-03-01 | 1985-03-01 | Fourier transform method Infrared film thickness measurement method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60038707A JPH0721405B2 (en) | 1985-03-01 | 1985-03-01 | Fourier transform method Infrared film thickness measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61200407A true JPS61200407A (en) | 1986-09-05 |
| JPH0721405B2 JPH0721405B2 (en) | 1995-03-08 |
Family
ID=12532785
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60038707A Expired - Lifetime JPH0721405B2 (en) | 1985-03-01 | 1985-03-01 | Fourier transform method Infrared film thickness measurement method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0721405B2 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02152250A (en) * | 1988-12-02 | 1990-06-12 | Nec Corp | Evaluation of epitaxial growth layer |
| EP0420113A2 (en) * | 1989-09-25 | 1991-04-03 | Mitsubishi Denki Kabushiki Kaisha | Apparatus for and method of evaluating multilayer thin films |
| US5654394A (en) * | 1994-04-08 | 1997-08-05 | Toray Industries, Inc. | Thermoplastic resin film |
| DE102007062052A1 (en) * | 2007-12-21 | 2009-06-25 | Siemens Ag | Layer thickness measurement on transparent layers |
| US7753167B2 (en) | 2005-01-13 | 2010-07-13 | Smc Kabushiki Kaisha | Silencer |
| CN107860722A (en) * | 2017-10-30 | 2018-03-30 | 内蒙古农业大学 | A kind of honeydew melon inside quality online test method and system |
| CN114935313A (en) * | 2022-04-26 | 2022-08-23 | 香港中文大学（深圳） | Film thickness measuring method, device, equipment and computer program product |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS564842A (en) * | 1979-06-26 | 1981-01-19 | Nec Corp | Microprogram control unit |
| JPS59105508A (en) * | 1982-12-08 | 1984-06-18 | Canon Inc | Measurement of whith interference film thickness |
-
1985
- 1985-03-01 JP JP60038707A patent/JPH0721405B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS564842A (en) * | 1979-06-26 | 1981-01-19 | Nec Corp | Microprogram control unit |
| JPS59105508A (en) * | 1982-12-08 | 1984-06-18 | Canon Inc | Measurement of whith interference film thickness |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02152250A (en) * | 1988-12-02 | 1990-06-12 | Nec Corp | Evaluation of epitaxial growth layer |
| EP0420113A2 (en) * | 1989-09-25 | 1991-04-03 | Mitsubishi Denki Kabushiki Kaisha | Apparatus for and method of evaluating multilayer thin films |
| US5227861A (en) * | 1989-09-25 | 1993-07-13 | Mitsubishi Denki Kabushiki Kaisha | Apparatus for and method of evaluating multilayer thin film |
| US5654394A (en) * | 1994-04-08 | 1997-08-05 | Toray Industries, Inc. | Thermoplastic resin film |
| US7753167B2 (en) | 2005-01-13 | 2010-07-13 | Smc Kabushiki Kaisha | Silencer |
| DE102007062052A1 (en) * | 2007-12-21 | 2009-06-25 | Siemens Ag | Layer thickness measurement on transparent layers |
| CN107860722A (en) * | 2017-10-30 | 2018-03-30 | 内蒙古农业大学 | A kind of honeydew melon inside quality online test method and system |
| CN107860722B (en) * | 2017-10-30 | 2020-04-21 | 内蒙古农业大学 | Method and system for online detection of internal quality of honeydew melons |
| CN114935313A (en) * | 2022-04-26 | 2022-08-23 | 香港中文大学（深圳） | Film thickness measuring method, device, equipment and computer program product |
| CN114935313B (en) * | 2022-04-26 | 2023-09-15 | 香港中文大学（深圳） | Film thickness measurement method, apparatus, device, and computer-readable storage medium |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0721405B2 (en) | 1995-03-08 |
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