JPS6287829A - Specimen for infrared absorption analysis - Google Patents

Abstract

PURPOSE:To obtain certain information relation to the molecular orientation of a membrane, by performing infrared spectrophotometric measurement using a specimen which is obtained by forming a solid membrane having a thickness permitting the transmission of a part of infrared rays on a monocrystalline silicon substrate and further forming a membrane for obtaining an infrared absorption spectrum on said solid membrane. CONSTITUTION:A specimen is formed by forming a platinum membrane 6 on the main surface of a monocrystalline silicon substrate 5, to which mirror surface finish has been applied, by sputtering or vapor deposition and depositing a membrane 2 composed of a substance desired to obtain an infrared absorption spectrum to the surface of the membrane 6. Thereafter, the transmitted spectrum is measured and, further, the specimen is used as it is to measure a reflected spectrum. Therefore, both of transmitted and reflected spectra can be measured using the same specimen as it is and, as a result, the accuracy of information obtained by the comparison of both spectra can be increased without considering the difference of the specimen. Further, a specimen that is a combination of a large number of substances can be formed and information useful for molecular orientation is obtained.

Description

【発明の詳細な説明】 〔発明の属する技術分野〕 本発明は薄膜の分子構造や分子配向などを調べるための
赤外吸収分析試料に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an infrared absorption analysis sample for investigating the molecular structure, molecular orientation, etc. of a thin film.

〔従来技術とその問題点〕[Prior art and its problems]

赤外吸収分析法は単分子膜や累積膜など薄膜の分子構造
９分子配向などの研究に広く用いられ、その赤外吸収ス
ペクトルを得るために透過法と反射法が知られている。Infrared absorption spectroscopy is widely used to study the molecular structure and orientation of thin films such as monomolecular films and cumulative films, and transmission methods and reflection methods are known for obtaining infrared absorption spectra.

第６図、第７図はこれらの方法を説明するための模式図
である。第６図は透過法を示したものであり、赤外光を
透過する臭化カリウム（ＫＢｒ）などの結晶板１の表面
に形成した薄膜２の側から矢印で表わした垂直な方向に
赤外光３を照射し、透過赤外光から赤外吸収スペクトル
を得るものである。第７図は反射法を示しており、金属
板４の表面に形成した薄膜２に対して赤外光３を斜めに
入射し、矢印方向に金属板４の表面で反射する赤外光か
ら赤外吸収スペクトルを得るものである。この反射法は
大きな入射角と入射面に平行な偏光を用いる高感度反射
法が金属板上の例えば数十Ａ〜数百Ａのようなとくに薄
い膜の赤外吸収スペクトルを得るのに有効であることが
雑誌分光研究第３１巻第３号（１９８２）末高治により
報告されている。FIGS. 6 and 7 are schematic diagrams for explaining these methods. Figure 6 shows the transmission method, in which infrared light is transmitted from the side of a thin film 2 formed on the surface of a crystal plate 1 such as potassium bromide (KBr) that transmits infrared light in the perpendicular direction indicated by the arrow. Light 3 is irradiated to obtain an infrared absorption spectrum from the transmitted infrared light. FIG. 7 shows the reflection method, in which infrared light 3 is obliquely incident on the thin film 2 formed on the surface of the metal plate 4, and the infrared light reflected from the surface of the metal plate 4 changes in the direction of the arrow. This is to obtain an external absorption spectrum. This high-sensitivity reflection method, which uses large incident angles and polarized light parallel to the plane of incidence, is effective for obtaining infrared absorption spectra of particularly thin films, such as tens of amperes to hundreds of amperes, on metal plates. Something has been reported by Osamu Suetaka in the magazine Spectroscopy Research Vol. 31, No. 3 (1982).

以上二つの方法において赤外光の入射した薄膜部分に赤
外光によって形成される電場の向きは、透過法では基板
表面に対して平行であり、反射法では基板表面に対して
垂直となるので透過法で得られるスペクトルと反射法で
得られるスペクトルを比較することにより薄膜の分子配
向などを知ることができることも上記文献などから知ら
れている。In the above two methods, the direction of the electric field formed by the infrared light on the thin film part where the infrared light is incident is parallel to the substrate surface in the transmission method, and perpendicular to the substrate surface in the reflection method. It is also known from the above-mentioned literature that the molecular orientation of a thin film can be determined by comparing the spectrum obtained by the transmission method and the spectrum obtained by the reflection method.

しかしながら、透過法と反射法により得られたスペクト
ルを比較する方法は前述のように透過法はＫＢｒ結晶を
基板とし、反射法では基板に金属板を用いており、それ
ぞれ異なる基板上に薄膜を形成するので比較すべき試料
は別々のものとなり、とくに分子配向については基板の
相違によって薄膜の分子配向も異なり、透過法測定試料
と反射性測定試料とで分子配向が等しいという保証が得
られないために、基板の影響を無視することができなく
なる０ したがって従来試料では、薄膜の分子配向があるとき、
透過法と反射法とでスペクトルが異なることや、赤外光
の屈折率の異常分散に基づくスペクトルの差異が起り得
ることに、さらに基板の影響が重畳されるので、透過ス
ペクトルト反射スペクトルの両者からｉｖ膜の分子配向
を正確ｌこ把握することが困難な場合があり、分子配向
に関する判断を簡単に行なうことができないという欠点
をもっている。However, as mentioned above, the method of comparing spectra obtained by the transmission method and the reflection method uses a KBr crystal as a substrate in the transmission method, and a metal plate as the substrate in the reflection method, and thin films are formed on different substrates. Therefore, the samples to be compared are different, and in particular, the molecular orientation of the thin film differs depending on the substrate, and it cannot be guaranteed that the molecular orientation is the same between the transmission measurement sample and the reflection measurement sample. Therefore, in conventional samples, when there is molecular orientation in the thin film, the influence of the substrate cannot be ignored.
In addition to the fact that the spectra differ between the transmission method and the reflection method, and the possibility of spectral differences based on the anomalous dispersion of the refractive index of infrared light, the influence of the substrate is also superimposed, so that both the transmission and reflection spectra are different. In some cases, it is difficult to accurately determine the molecular orientation of the IV film, and it has the disadvantage that it is not possible to easily judge the molecular orientation.

〔発明の目的〕[Purpose of the invention]

本発明の目的は上述の欠点を除去し、薄膜の分子配向に
関してより確かな情報が得られる赤外吸収分析試料を提
惧することにある。The object of the present invention is to eliminate the above-mentioned drawbacks and to provide an infrared absorption analysis sample that provides more reliable information regarding the molecular orientation of a thin film.

〔発明の要点〕[Key points of the invention]

本発明は単結晶シリコン板上に赤外光の一部を透過する
厚さの金属などの第一の固体薄膜を設け、この上に赤外
吸収スペクトルを得るための第二の薄膜を形成したもの
を試料として、この一つの試料を用いて透過法と反射法
の両方法による赤外分光測定を行ない、得られた薄膜の
分子配向などに関する確かな情報が得られるようにした
ものである０ 〔発明の実施例〕 以下本発明を実施例１こ基づき説明する。In the present invention, a first solid thin film made of metal or the like having a thickness that transmits a part of infrared light is provided on a single crystal silicon plate, and a second thin film for obtaining an infrared absorption spectrum is formed on this. This method uses a single sample as a sample and performs infrared spectroscopic measurements using both transmission and reflection methods to obtain reliable information regarding the molecular orientation of the resulting thin film. [Example of the Invention] The present invention will be explained below based on Example 1.

第１図、第２図は本発明により得られる試料と赤外光の
挙動をそれぞれ第６図、第７図に做って模式図で示した
ものであり共通部分は同一符号で表わしである。また赤
外光３の進行方向を第６図。Figures 1 and 2 are schematic diagrams showing the behavior of a sample obtained by the present invention and infrared light, similar to Figures 6 and 7, respectively, and common parts are represented by the same symbols. . Further, FIG. 6 shows the traveling direction of the infrared light 3.

第７図と同様に矢印により示した〇 第１図は透過法の場合である。第１図においてまず厚さ
０．２〜１　ｍｍ程度の鏡面仕上げを施した単結晶シリ
コン基板５の主面上に厚さ５０〜２００Ａ程度の白金薄
膜６をスパッターもしくは蒸着などにより形成し、この
白金薄膜面上に赤外吸収スペクトルを得たい物質の薄膜
２を被着したものを試料として作製した後透過スペクト
ル測定を行なう。Figure 1, which is indicated by arrows in the same way as Figure 7, is the case of the transmission method. In FIG. 1, first, a platinum thin film 6 with a thickness of about 50 to 200 A is formed by sputtering or vapor deposition on the main surface of a mirror-finished single crystal silicon substrate 5 with a thickness of about 0.2 to 1 mm. A thin film 2 of a substance whose infrared absorption spectrum is to be obtained is coated on the surface of a platinum thin film, and then a transmission spectrum is measured.

第２図は高感度反射法の場合であり、第１図に示した透
過スペクトルを測定した試料をそのまま用いて同一試料
で反射スペクトル測定を行なう。すなわち本発明では透
過法と反射法とで試料を変えることなく、基板を単結晶
シリコン板５とし被測定薄膜２との間に白金薄膜６が介
在するようにした共通の試料を用いて透過法と反射法に
よるスペクトル測定に供している。FIG. 2 shows the case of the high-sensitivity reflection method, in which the reflection spectrum is measured using the same sample as shown in FIG. 1, the transmission spectrum of which was measured. That is, in the present invention, without changing the sample between the transmission method and the reflection method, a common sample in which the substrate is a single crystal silicon plate 5 and the thin film to be measured 2 and the platinum thin film 6 is interposed is used for the transmission method. and spectrum measurements using the reflection method.

第１図、第２図において単結晶シリコン板５は赤外光を
約５０チ透過し、この単結晶シリコン板５の上に白金薄
膜６を５０〜２００Ａの厚さにスパッターもしくは蒸着
により被着しても赤外光の一部を透過する。例えば厚さ
約１０ＯＡの白金薄膜６が被着された単結晶シリコン板
５の赤外光に対する透過率は約２５％である。この程度
の透過率があれば第１図のような透過法によるスペクト
ル測定は十分可能である。また単結晶シリコン板５は屈
折率が約３．４と大きいので、この上に被着した白金薄
膜６が非常に薄い場合でも比較的大きな反射率が得られ
、さらにこの白金薄膜６の上に形成された薄膜２は第２
図のような高感度反射法による吸収スペクトルを得るこ
とが可能である。In FIGS. 1 and 2, a single crystal silicon plate 5 transmits about 50 infrared rays, and a platinum thin film 6 is deposited on the single crystal silicon plate 5 to a thickness of 50 to 200 Å by sputtering or vapor deposition. However, some infrared light is transmitted through it. For example, the transmittance of the single crystal silicon plate 5 coated with the platinum thin film 6 having a thickness of about 10 OA for infrared light is about 25%. With this level of transmittance, spectrum measurement by the transmission method as shown in FIG. 1 is fully possible. Furthermore, since the single crystal silicon plate 5 has a large refractive index of about 3.4, a relatively large reflectance can be obtained even if the platinum thin film 6 deposited thereon is very thin. The formed thin film 2 is the second
It is possible to obtain an absorption spectrum using the high-sensitivity reflection method as shown in the figure.

第３図は単結晶シリコン板上に白金を１０ＯＡの厚さ（
こ被着した後、この白金膜の上にさらに２５０Ｘの厚さ
の酸化シリコン（Ｓｉｆｔ）膜を形成した試料を透過法
と反射法で測定した赤外スペクトルの透過率と反射率を
示した線図である０赤外分光計はフーリエ変換量赤外分
光計を用い反射法では赤外光の入射角７５°　とし平行
偏光により行なった。スペクトル測定は透過法９反射法
共にダブルビーム方式でぴ昭光側に白金を１００Ａｉ着
した単結晶板を用いた０３ｉＯｚの膜厚はエリプソメー
タで測定した。第３図の測定結果から透過スペクトルは
ＫＢｒ結晶板上に８１０．膜を形成した従来の試料の場
合のスペクトルとほぼ同じであり、反射スペクトルは金
属板上に５ｉｎｔ膜を形成した従来の試料を用いたとき
とほぼ同じであることがわかった。第３図の両スペクト
ル線図は同一試料から得られたものであるから両線図の
相違は少くとも試料基板に基づくものではない。Figure 3 shows platinum deposited on a single crystal silicon plate to a thickness of 10OA (
After this deposition, a silicon oxide (Sift) film with a thickness of 250X was further formed on this platinum film.The line shows the transmittance and reflectance of the infrared spectrum measured by transmission method and reflection method. The 0 infrared spectrometer shown in the figure is a Fourier transform infrared spectrometer, and the reflection method was conducted using parallel polarized light at an incident angle of 75°. The spectra were measured using a double beam method for both the transmission method and the reflection method.The film thickness of 03iOz was measured using an ellipsometer using a single crystal plate with 100Ai of platinum deposited on the optical side. From the measurement results shown in Figure 3, the transmission spectrum is 810. It was found that the spectrum was almost the same as that of a conventional sample in which a film was formed, and the reflection spectrum was found to be almost the same as that in the case of a conventional sample in which a 5-inch film was formed on a metal plate. Since both spectral diagrams in FIG. 3 were obtained from the same sample, the difference between the two diagrams is not at least based on the sample substrate.

第４図は第３図に用いた試料と同様に単結晶シリコン板
上に被着した１００Ａの白金膜上に３００＾の厚さに弗
化カーボンオイルを塗布した試料について透過スペクト
ルと反射スペクトルを示したものである０反射測定は第
３図のときと同じく入射角７５°の平行偏光で行なった
Ｑ第４図の結果も両スペクトル線図の相違は試料基板に
よるものでなく被測定Ｗ！膜が分子配向をもつためと解
釈される０ 第５図も第３図、第４図と同じく単結晶シリコン板上に
１０ＯＡの白金膜を設け、その上に３５ＯＡの厚さのエ
ポキシワニスを塗布した試料の透過スペクトルと反射ス
ペクトルの線図である。反射測定は同じく入射角７５°
の平行偏光で行なった。Figure 4 shows the transmission spectrum and reflection spectrum of a sample in which fluorinated carbon oil was applied to a thickness of 300^ on a 100A platinum film deposited on a single crystal silicon plate, similar to the sample used in Figure 3. The 0 reflection measurement shown in Figure 3 was carried out using parallel polarized light with an incident angle of 75°.The difference between the two spectral diagrams in Figure 4 is not due to the sample substrate, but to the W! This is interpreted to be because the film has molecular orientation. 0 In Figure 5, as in Figures 3 and 4, a 10OA platinum film is provided on a single crystal silicon plate, and a 35OA thick epoxy varnish is applied on top of it. FIG. 2 is a diagram of the transmission spectrum and reflection spectrum of the sample. Reflection measurements are also made at an incident angle of 75°.
It was performed using parallel polarized light.

第５図の結果から両スペクトル線図はほぼ同じであって
この場合分子配量がないと判断される。From the results shown in FIG. 5, both spectral diagrams are almost the same, and it is determined that there is no molecular distribution in this case.

以上のように単結晶シリコン板上に白金を１０ＯＡスパ
ツターもしくは蒸着により被着し、さらにその上に薄膜
を仮着または塗布して形成したものを試料として透過法
と反射法による薄膜の吸収スペクトル測定を同一試料で
行なうことが可能となり、得られたスペクトル線図の解
釈に対して試料基板の相違に関する因子を取り除くこと
ができる。As described above, platinum was deposited on a single crystal silicon plate by sputtering or vapor deposition at a rate of 10 OA, and then a thin film was temporarily deposited or coated on top of the plate, and the absorption spectrum of the thin film was measured using a transmission method and a reflection method. can be performed on the same sample, and factors related to differences in sample substrates can be removed from the interpretation of the obtained spectral diagram.

また本発明の試料を用いる場合反射スペクトルは金属板
上に形成した薄膜の高感度反射スペクトルに匹敵する吸
収強度を示し、２５０〜３５０Ａのような薄い膜の吸収
スペクトルを得ることが可能である。Further, when using the sample of the present invention, the reflection spectrum shows an absorption intensity comparable to the high-sensitivity reflection spectrum of a thin film formed on a metal plate, and it is possible to obtain an absorption spectrum of a thin film such as 250 to 350 A.

さらに本発明による試料は単結晶シリコン板上に設ける
第１の薄膜として白金膜のほかに各穐の金属膜や金属酸
化物の薄膜を用いてもよい。したがって本発明の試料は
単結晶シリコン板上に形成する第１の薄膜とその上に形
成させて赤外吸収スペクトルを測定する第２の薄膜との
両薄膜にそれぞれ異なる多くの組み合わせをもたせるこ
とも可能であり、目的に応じて第１の薄膜と第２の薄膜
の物質を適宜選択して組み合わせることにより、第１の
薄膜と第２の薄膜との相互作用を分子配向などの観点か
ら調べることができる。Furthermore, in the sample according to the present invention, a metal film or a metal oxide thin film may be used in addition to the platinum film as the first thin film provided on the single crystal silicon plate. Therefore, the sample of the present invention may have many different combinations of the first thin film formed on the single crystal silicon plate and the second thin film formed thereon to measure the infrared absorption spectrum. It is possible to investigate the interaction between the first thin film and the second thin film from the viewpoint of molecular orientation, etc. by appropriately selecting and combining the materials of the first thin film and the second thin film depending on the purpose. I can do it.

なお本発明の試料は赤外吸収スペクトルを得たい物質を
第２の薄膜として形成する場合について説明してきたが
、吸着物質に対しても同様の効果を有することは明らか
であるから、試料作製時に薄膜に限ることなく、吸着物
質を第１の薄膜に付着させるようにしてもよいことは勿
論である。Although the sample of the present invention has been described with respect to the case in which the substance from which the infrared absorption spectrum is to be obtained is formed as a second thin film, it is clear that it has a similar effect on adsorbed substances as well, so when preparing the sample, Of course, the adsorbent substance is not limited to the thin film, and the adsorbed substance may be attached to the first thin film.

一方単結晶シリコン板はＫＢｒ結晶板などに比べて化学
的に安定であり、吸湿などの影響も少なくないので取り
扱いやすく、しかも入手容易で安価であるなどの長所を
もっているので本発明による試料は利用範囲も拡大する
ことができる。On the other hand, single-crystal silicon plates are chemically stable compared to KBr crystal plates, etc., and are easy to handle as they are not affected by moisture absorption, and they are easy to obtain and inexpensive. The range can also be expanded.

〔発明の効果〕〔Effect of the invention〕

薄膜の分子構造や分子配向を調べる；こ当り、薄膜の赤
外吸収スペクトルを得るために、透過法と反射法が用い
られるが従来は透過法と反射法とでそれぞれ異なる材料
からなる基板をもった別々の試料が用いられていたのに
対し、本発明によれば実施例で説明したように基板材料
は単結晶シリコン板のみを使用し、この基板上に赤外光
を一部透過する程度の厚さをもつ第１の薄膜を形成した
後、この薄膜上ｆこさらに赤外吸収スペクトルを得たい
第２の薄膜を被着した試料としたために、透過法と反射
法とで試料を変えることなく、同一試料のまま透過スペ
クトルと反射スペクトルを測定することが可能になった
。この結果、両スペクトルを比較し′４膜の分子配向な
どの解釈を行なうとき少くとも試料の相違に基づくスペ
クトルの相違は考慮する必要がなくなり、得られる情報
の正確度を増すことができる。また本発明による試料の
他の利点は第１の薄膜に各種の金属や金属酸化物を用い
、第２の薄膜に有機または無機物質を用いるなと多くの
物質を組合わせた試料を作ｙ！メすることが可能である
から機能性薄膜や触媒などに関する分野で分子配向など
の有用な情報が得られることである。Investigating the molecular structure and molecular orientation of thin films; transmission and reflection methods are used to obtain infrared absorption spectra of thin films, but conventionally, transmission and reflection methods each require a substrate made of different materials. In contrast, according to the present invention, as explained in the examples, only a single-crystal silicon plate is used as the substrate material. After forming a first thin film with a thickness of It is now possible to measure the transmission spectrum and reflection spectrum of the same sample without having to do so. As a result, when comparing the two spectra and interpreting the molecular orientation of the '4 film, there is no need to take into account at least the difference in the spectra due to the difference in the sample, and the accuracy of the information obtained can be increased. Another advantage of the sample according to the present invention is that the first thin film is made of various metals or metal oxides, and the second thin film is made of an organic or inorganic substance. Because it is possible to measure molecular orientation, useful information such as molecular orientation can be obtained in fields related to functional thin films and catalysts.

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

第１図は梨発明による試料の透過法を示す模式図、第２
図は同じく反射法を示す模式図、第３図〜第５図は本発
明の試料を用いて得られた赤タ１吸収スペクトル線図、
第６凶は従来試料の透過法を示す模式図、第７図は同じ
く反射法を示す模式図である。 ２　・薄膜、３・・・赤外光、５・・・単結晶シリコン
基第１図　　　　　第２図 波数（Ｃｍ’−’） 第３図 波数（Ｃｍ−り 第５図 第６図　　　　　１７図Figure 1 is a schematic diagram showing the sample transmission method according to Nashi's invention, Figure 2
The figure is also a schematic diagram showing the reflection method, and Figures 3 to 5 are Akata 1 absorption spectrum diagrams obtained using the sample of the present invention.
No. 6 is a schematic diagram showing a transmission method for a conventional sample, and FIG. 7 is a schematic diagram also showing a reflection method. 2 - Thin film, 3... Infrared light, 5... Single crystal silicon base Fig. 1 Fig. 2 Wave number (Cm'-') Fig. 3 Wave number (Cm-ri Fig. 5 Fig. 6 Fig. 17

Claims (1)

【特許請求の範囲】 １）単結晶シリコン板の一主面上に被着した赤外光を一
部透過する厚さの第１の薄膜と、該第１の薄膜上に被着
した赤外吸収スペクトルを測定する前記第１の薄膜とは
異なる第２の薄膜を備えたことを特徴とする赤外吸収分
析試料。 ２）特許請求の範囲第１項記載の試料において、第１の
薄膜に金属または金属酸化物を用いることを特徴とする
赤外吸収分析試料。 ３）特許請求の範囲第１項または第２項記載の試料にお
いて、同一試料を用いて透過法と反射法による赤外吸収
スペクトルが測定可能なことを特徴とする赤外吸収分析
試料。[Scope of Claims] 1) A first thin film deposited on one principal surface of a single crystal silicon plate and having a thickness that partially transmits infrared light, and a first thin film deposited on the first thin film. An infrared absorption analysis sample comprising a second thin film different from the first thin film whose absorption spectrum is to be measured. 2) An infrared absorption analysis sample according to claim 1, characterized in that a metal or a metal oxide is used for the first thin film. 3) An infrared absorption analysis sample according to claim 1 or 2, characterized in that infrared absorption spectra can be measured by a transmission method and a reflection method using the same sample.