JPS6228606A - Film thickness measuring instrument - Google Patents

Abstract

PURPOSE:To easily and accurately measure the thickness of a film, by providing at least two pairs of a light source which irradiates rays of light at different incident angles and a detector for detecting reflecting light and irradiating rays of light of the same wavelength from each light source. CONSTITUTION:Two sets of light sources 1a and 1b and two sets of reflecting light detectors 2a and 2b are provided. Rays of light having the same wavelength are used as those irradiated from the light sources 1a and 1b. The reflecting lights from the two light sources 1a and 1b are respectively detected with the detectors 2a and 2b and arithmetic units 5a and 5b perform prescribed operation processes on the detected data. The periodicity values thus obtained are compared with each other at a relational arithmetic unit 6 and the one when the two values coincide with each other is used as the true thickness of a film. The value of the true film thickness thus obtained is displayed through a display device 7. Therefore, the thickness of a film can be measured easily and accurately.

Description

【発明の詳細な説明】 〔発明の技術分野〕 本発明は半導体ウェー八等の上に形成された酸化膜、窒
化膜、多結晶シリコン膜等の薄膜や、エリプソメトリ周
期が短かい膜種の膜厚を測定する膜厚測定装置に関する
。Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to thin films such as oxide films, nitride films, and polycrystalline silicon films formed on semiconductor wafers, etc., and film types with short ellipsometry periods. The present invention relates to a film thickness measuring device that measures film thickness.

〔発明の技術的前■とその問題点〕[Technical background of invention■ and its problems]

エリブソメ１−りを利用した膜厚測定装置の従来例を第
３図に示す。一定波長の光線を照射する光源１と、反射
された光線を検知する検知器２とが１対配設されている
。試料３は試料台４の上に載置されており、試料３の表
面には薄膜が形成されている。しかしながらこの装置で
は、測定に当っては第３図に点線で示すように光線の入
射角を変化させるため光源の角度を測定者が変え、各角
度で測定して得られたエリプソメトリ周期毎の膜厚値か
ら、数値が同一の測定値を膜厚として求めなければなら
ない。このため、操作が煩雑である。FIG. 3 shows a conventional example of a film thickness measuring device using an ellipsometry. A pair of light sources 1 that emit light of a constant wavelength and detectors 2 that detect reflected light are provided. The sample 3 is placed on a sample stage 4, and a thin film is formed on the surface of the sample 3. However, with this device, during measurement, the operator changes the angle of the light source to change the incident angle of the light ray, as shown by the dotted line in Figure 3, and the ellipsometry period obtained by measuring at each angle is From the film thickness value, a measured value with the same numerical value must be determined as the film thickness. Therefore, the operation is complicated.

このような装置の他に、異なる波長の光線を照射する光
源と、各光源からの光線が反射された光線を検知する検
知器とが２対配設されたものが。In addition to such devices, there are two pairs of light sources that emit light of different wavelengths and detectors that detect the reflected light from each light source.

従来から使用されている。しかしながらこの装置では、
照射される光線のうちの一方の波長の光は安定であるが
、他方の波長光は不安定で寿命が短かく、信頼性に欠け
ている。Traditionally used. However, with this device,
The light of one wavelength among the irradiated light beams is stable, but the light of the other wavelength is unstable, has a short lifetime, and lacks reliability.

〔発明の目的〕[Purpose of the invention]

本発明は上記事情を考慮してなされたもので、試料表面
に形成された膜の厚さの測定を簡単に、しかも正確に行
なうことができる膜厚測定装置を提供Ｊ“ることを目的
としている。The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a film thickness measuring device that can easily and accurately measure the thickness of a film formed on a sample surface. There is.

〔発明の概要〕[Summary of the invention]

上記の目的を達成するため本発明は、照射する光線の入
射角が異なるように配設された光源と、各反射光を検知
する検出器とが少なくとも２対配設されており、各光源
から同一波長の光線を照射し、それぞれの光照射で得ら
れた数値から膜厚を測定する膜厚測定装置を提供するも
のである。In order to achieve the above object, the present invention includes at least two pairs of light sources arranged so that the incident angles of the irradiated light rays are different, and at least two pairs of detectors for detecting each reflected light. The present invention provides a film thickness measuring device that irradiates light beams of the same wavelength and measures the film thickness from the numerical values obtained with each light irradiation.

〔発明の実施例〕 以下、本発明の一実施例を第１図および第２図を参照し
て説明する。[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

第１図に示す実施例では、光源ｉａ、１ｂが２基設けら
れ、反射光の検出器２ａ、２ｂが２基設けられている。In the embodiment shown in FIG. 1, two light sources ia and 1b are provided, and two reflected light detectors 2a and 2b are provided.

すなわち、光１１ａ、ｌｂと検出Ｗ２ａ、２ｂの組が２
対配設されている。これらはいずれも試料台４上に載置
される半導体ウェー八等の試料３の上方に固定され、一
方の光源１ａは試料３の法線に対して７０度の入射角で
光線を照射するようにセットされ、他方の光源１ｂは法
線に対して３０度の入射角で光線を照射するようにセラ
１〜されている。従って、８光Ｆｔ１ａ、ｉｂに対応し
て反射光を検知する検出器２ａ、　２ｂも、法線に対し
てそれぞれ同様の角度でセットされる。That is, there are two sets of light 11a, lb and detection W2a, 2b.
It is arranged against. All of these are fixed above a sample 3 such as a semiconductor wafer 8 placed on a sample stage 4, and one light source 1a is configured to irradiate a light beam at an incident angle of 70 degrees with respect to the normal line of the sample 3. The other light source 1b is set to emit light at an incident angle of 30 degrees with respect to the normal line. Therefore, the detectors 2a and 2b that detect the reflected lights corresponding to the eight lights Ft1a and ib are also set at similar angles to the normal.

光源１ａ、ｌｂから照射された光線は、試料３の上面に
形成されたｉ９膜および試料面で反射されて検出器２ａ
、２ｂに検知され、これにより膜厚が測定される。ここ
で、８光１１ａ、１ｂから照射される光線としては同一
波長のものが使用される。この波長光としては安定性が
よく、しかも反射性のよいものが使用され、例えばヘリ
ウム−ネオンレーザ光が選択される。安定した波長光を
使用することで正確な測定が可能となり、しかも光源の
寿命が長くなる。The light rays emitted from the light sources 1a and lb are reflected by the i9 film formed on the upper surface of the sample 3 and the sample surface, and are directed to the detector 2a.
, 2b, and the film thickness is thereby measured. Here, the light beams emitted from the eight lights 11a and 1b are of the same wavelength. As this wavelength light, one having good stability and good reflectivity is used; for example, helium-neon laser light is selected. Using stable wavelength light enables accurate measurements and extends the life of the light source.

膜厚の測定はエリプソメトリ法で行なわれる。The film thickness is measured by ellipsometry.

すなわち第２図に示すように、２つの光源１ａ。That is, as shown in FIG. 2, two light sources 1a.

１ｂの反射光を検出器２ａ、２ｂで検出し、この検出デ
ータに対して演算装置５ａ、５ｂで所定の演τ）処理を
施す。このようにして得られた周期数値を比較演算装置
６で比較し、それぞれの数値が一致したものを真の膜厚
とすることができる。この真の膜厚値は表示装置７で表
示される。この場合、測定方法は従来と同様であるので
、測定の制御およびデータ処理は演算装置５ａ、５ｂお
よび比較演算装置６を構成するパーソナルコンビューク
等のプログラムを変更するだけで簡単に行なうことがで
きる。1b is detected by detectors 2a and 2b, and arithmetic units 5a and 5b perform a predetermined operation τ) on the detected data. The periodic values obtained in this manner are compared by the comparison calculation device 6, and the one where the respective numerical values match can be determined as the true film thickness. This true film thickness value is displayed on the display device 7. In this case, since the measurement method is the same as the conventional method, measurement control and data processing can be easily performed by simply changing the program of the personal computer etc. that constitutes the arithmetic units 5a, 5b and the comparison arithmetic unit 6. can.

次に、波長６３２８人のへリウムーネＡンレーザを、試
料３に対して入射角３０度、７０度となるように光ｇｉ
ａ、ｉｂをセラｌ−ｔ、た装置を使用して、シリコンウ
ェーハ３上に形成された屈折率１．４５、膜厚６０００
人の酸化膜の膜厚を測定する場合を説明する。光源１ｂ
から入射角３０度で照射され、試料で反射された光を検
出器２ｂで検知した数値は、 １３５１人、３６７５人。Next, a heliumone A laser with a wavelength of 6,328 people was applied to the sample 3 at an incident angle of 30 degrees and 70 degrees.
A film with a refractive index of 1.45 and a film thickness of 6000 was formed on a silicon wafer 3 using an apparatus in which
A case will be explained in which the thickness of an oxide film on a person is measured. light source 1b
The numbers detected by detector 2b of the light irradiated from the sample at an incident angle of 30 degrees and reflected by the sample were 1,351 and 3,675, respectively.

６０００人、８３２５人・・・ であり、２３２５人の周期となる。光源１ａから入射角
７０度で照射され、反射した光を検出器２ａで検知した
数値は、 ２７０人、３１３５人。6000 people, 8325 people, etc., resulting in a cycle of 2325 people. The numbers detected by the detector 2a of the reflected light emitted from the light source 1a at an incident angle of 70 degrees were 270 and 3135 people.

６０００人、８８６５人・・・ であり、２８６５への周期となる。従って、測定によっ
て１ｎられる膜厚は上記２種の数値が一致した６０００
人となり、正確な膜厚データが１″＃られる。6,000 people, 8,865 people, etc., resulting in a cycle to 2,865. Therefore, the film thickness determined by measurement is 6000, which is the same as the above two values.
Accurate film thickness data will be obtained.

なお、本発明においては光源と検出器を３対以上設けて
もよく、これにより精度の向上と測定時間の短縮が可能
となる。又、光線の入射角度も図示の実施例に限らす、
種々変更が可能である。In addition, in the present invention, three or more pairs of light sources and detectors may be provided, thereby making it possible to improve accuracy and shorten measurement time. Also, the incident angle of the light beam is limited to the illustrated embodiment.
Various changes are possible.

〔発明の効果〕〔Effect of the invention〕

以上の通り本発明によれば、異なる入射角で光線を照Ｃ
Ｊする光源と反射光を検知する検出器を少なくとし２基
対以上配設し、各光源から同一波長の光線を照射するよ
うにしたので、ｒＩＱ厚の測定が簡易に、しかも正確に
行なうことができ、連続測定を迅速に行なうことができ
る膜厚ａｌｌｌ定装冒が得られる。As described above, according to the present invention, light beams are emitted at different angles of incidence.
By reducing the number of light sources and detectors for detecting reflected light and arranging two or more pairs, each light source emits light of the same wavelength, making it possible to easily and accurately measure rIQ thickness. It is possible to obtain a fixed setup for all film thicknesses that allows rapid continuous measurement.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例の要部の正面図、第２図は同
実施例の構成を示すブロック図、第３図は従来装置の一
例の要部の正面図である。 １ａ、１ｂ・・・光源、２ａ、２ｂ・・・検出器、３・
・・試料。 出願人代理人　　佐　　藤　　−雄 Ｐ）１　　図 も２　図 ５３　図FIG. 1 is a front view of a main part of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of the same embodiment, and FIG. 3 is a front view of a main part of an example of a conventional device. 1a, 1b...light source, 2a, 2b...detector, 3.
··sample. Applicant's agent: Sato-O P) 1 Figure also 2 Figure 53 Figure

Claims (1)

【特許請求の範囲】[Claims] 　表面に薄膜が形成された試料を置く試料台と、この試
料台上の試料に対して第１の入射角度で光を照射する第
１の光照射手段と、前記試料面で反射された前記第１の
光照射手段からの光を検出する第１の検出手段と、前記
試料台上の試料に対して第２の入射角度で前記第１の光
照射手段と同一波長の光を照射する第２の光照射手段と
、前記試料面で反射された前記第２の光照射手段からの
光を検出する第２の検出手段と、前記第１および第２の
検出手段の出力信号にもとづいてエリプソメトリ周期毎
の膜厚値を演算する演算手段と、この演算手段の演算結
果をそれぞれ比較して真の膜厚値を求める比較手段とを
備える膜厚測定装置。a sample stage on which a sample having a thin film formed on its surface is placed; a first light irradiation means for irradiating the sample on the sample stage with light at a first incident angle; a first detection means for detecting light from the first light irradiation means; and a second detection means for irradiating the sample on the sample stage with light having the same wavelength as that of the first light irradiation means at a second incident angle. ellipsometry based on the output signals of the first and second detection means; A film thickness measuring device comprising a calculation means for calculating a film thickness value for each period, and a comparison means for comparing the calculation results of the calculation means to obtain a true film thickness value.