JP2810194B2 - Interference optical system and exposure apparatus having the same - Google Patents
Interference optical system and exposure apparatus having the sameInfo
- Publication number
- JP2810194B2 JP2810194B2 JP2053596A JP5359690A JP2810194B2 JP 2810194 B2 JP2810194 B2 JP 2810194B2 JP 2053596 A JP2053596 A JP 2053596A JP 5359690 A JP5359690 A JP 5359690A JP 2810194 B2 JP2810194 B2 JP 2810194B2
- Authority
- JP
- Japan
- Prior art keywords
- measurement
- light
- interference
- optical path
- optical system
- 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 - Fee Related
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70691—Handling of masks or workpieces
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、光の干渉を応用した干渉計測において、大
気の揺らぎの影響を低減した干渉光学系及びそれを用い
た露光装置に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference optical system that reduces the influence of atmospheric fluctuations in interference measurement using light interference, and an exposure apparatus using the same.
光の干渉現象を応用した計測は、高精度非接触測定が
可能なことから多くの分野の精密計測に利用されてい
る。しかし、実際に高精度測定を実現するためには、光
学系の振動，熱変形，大気のゆらぎ等による種々の誤差
要因を低減しなければならない。これらの誤差要因のう
ち、大気のゆらぎの影響に関しては0 plus E No.91（19
87）第99頁から第105頁および0 plus E No.96（1987）
第107頁から第113頁に詳しく論じられており、その対策
の一つとして参照光路および測定光路を風よけカバーで
覆う方法がある。The measurement using the light interference phenomenon is used for precision measurement in many fields because non-contact measurement with high accuracy is possible. However, in order to actually realize high-accuracy measurement, it is necessary to reduce various error factors due to vibrations of the optical system, thermal deformation, fluctuations in the atmosphere, and the like. Among these error factors, regarding the effects of atmospheric turbulence, see 0 plus E No.91 (19
87) Pages 99 to 105 and 0 plus E No. 96 (1987)
This is discussed in detail on pages 107 to 113, and one of the measures is to cover the reference light path and the measurement light path with a windshield cover.
〔発明が解決しようとする課題〕 しかし、上記従来技術はカバー内空気の経時的な温度
安定化の点、および、大気の圧力変動や湿度変動により
屈折率が変化する点について考慮されておらず、参照光
と測定光の光路長が長時間の周期で変動し、測定誤差を
生じるという問題があった。[Problems to be Solved by the Invention] However, the above prior art does not consider the point of temperature stabilization of the air in the cover over time, and the point that the refractive index changes due to atmospheric pressure fluctuation and humidity fluctuation. In addition, there has been a problem that the optical path length of the reference light and the measurement light fluctuates in a long period, causing a measurement error.
本発明の目的は干渉計測において参照光路と測定光路
に温度の異なる空気の塊、即ち、大気のゆらぎが、直接
あたらないようにし、更に大気の圧力変動や湿度変動に
よって光路媒質の屈折率が変動しない干渉光学系及びそ
れを用いた露光装置を提供することにある。An object of the present invention is to prevent air masses having different temperatures in the reference optical path and the measurement optical path in interferometric measurement, that is, fluctuations in the atmosphere from directly hitting, and further, the refractive index of the optical path medium fluctuates due to fluctuations in atmospheric pressure and humidity. And an exposure apparatus using the same.
上記目的を達成するために、本発明は干渉光学系の参
照光路と測定光路中に使用波長に対して透明な固体物質
を挿入したものである。In order to achieve the above object, the present invention is such that a solid substance transparent to a used wavelength is inserted in a reference optical path and a measurement optical path of an interference optical system.
さらに、光路媒質の温度変化による測定誤差をより小
さくするために参照光路と測定光路に挿入する透明な固
体物質として、温度変化に対する光路長の変化がほとん
どないアサーマルガラス（Athermalglass）を用いたも
のである。Furthermore, in order to reduce the measurement error due to the temperature change of the optical path medium, as a transparent solid substance inserted into the reference optical path and the measurement optical path, a thermal glass (Athermalglass) having almost no change in the optical path length with respect to the temperature change is used. is there.
干渉光学系の参照光路と測定光路中に使用波長に対し
て透明な固体物質を挿入し、参照光と測定光を固体物質
の内部を透過させることにより、光路に直接温度の異な
る空気の塊があたるのを防止し、空気のゆらぎが測定精
度に及ぼす影響を除去できる。また、参照光と測定光が
透過する媒質が固体物質であるため、圧力変動や湿度変
動の影響を受けず、固体物質の温度が一定であれば光路
長が変化せず測定誤差は生じない。By inserting a solid material that is transparent to the wavelength used in the reference light path and the measurement light path of the interference optical system, and transmitting the reference light and the measurement light through the inside of the solid substance, air masses having different temperatures directly in the light path. It can be prevented from hitting and the influence of air fluctuation on the measurement accuracy can be eliminated. Further, since the medium through which the reference light and the measurement light pass is a solid substance, the medium is not affected by pressure fluctuations and humidity fluctuations. If the temperature of the solid substance is constant, the optical path length does not change and no measurement error occurs.
また、固体物質の温度を一定に保持できない場合は、
参照光路と測定光路に挿入する透明な固体物質として、
温度変化に対する光路長の変化がほとんどないアサーマ
ルガラス（Athermal glass）を用いることにより、測定
誤差の発生を最小限におさえることができる。If the temperature of the solid substance cannot be kept constant,
As a transparent solid substance inserted in the reference optical path and the measurement optical path,
By using an athermal glass having almost no change in the optical path length with respect to a temperature change, it is possible to minimize the occurrence of a measurement error.
以下、本発明の一実施例を第１図により説明する。第
１図は露光装置において、ウェハのチップ毎の高さと傾
きを干渉計を用いて計測する装置である。レーザ源１、
ハーフミラー２、反射ミラー６、キューブビームスプリ
ッタ７、参照ミラー５、レンズ８、リニアセンサ９、ガ
ラスバー10,11から成り、露光時、ウェハ16のチップ毎
の高さと傾きを検出する。３は参照ビーム、４は測定ビ
ームを示し、13は縮小レンズ、14はチルトステージ、15
はXYZステージである。この構成においてレーザ光の分
割と合成は以下のように行なう。すなわちレーザ源１を
出射した平行ビームはハーフミラー２により参照光３と
測定光４の２本のビームに分割する。参照光３は反射ミ
ラー６で反射した後、キューブハーフミラー７、ガラス
バー10を透過し、参照ミラー５に垂直に入射する。一
方、測定ビーム４は、キューブハーフミラー７、ガラス
バー10を透過した後、ウェハ16の表面で反射し、参照ミ
ラー５に垂直に入射する。参照ミラー５で反射した参照
ビーム３と測定ビーム４は、再び、元の光路を逆戻り
し、キューブハーフミラー７で反射後、レンズ８、ガラ
スバー11を透過し、リニアセンサ９上で重なり合い、干
渉縞を発生する。ここで参照ビーム３にはウェハ16の高
さと傾き情報が含まれている。従って、リニアセンサ９
上の干渉縞のピッチと位相変化を検出することによっ
て、ウェハ16の傾きと高さを知ることが可能となる。即
ち、ウェハ16が上，下に移動した場合は、干渉縞の位相
が変化し、ウェハ16が傾いた時は干渉縞のピッチが変化
する。Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows an exposure apparatus which measures the height and inclination of each wafer chip using an interferometer. Laser source 1,
It comprises a half mirror 2, a reflection mirror 6, a cube beam splitter 7, a reference mirror 5, a lens 8, a linear sensor 9, and glass bars 10 and 11, and detects the height and inclination of each chip of the wafer 16 during exposure. 3 is a reference beam, 4 is a measurement beam, 13 is a reduction lens, 14 is a tilt stage, 15
Is the XYZ stage. In this configuration, division and combination of laser light are performed as follows. That is, the parallel beam emitted from the laser source 1 is split by the half mirror 2 into two beams of the reference beam 3 and the measurement beam 4. After being reflected by the reflection mirror 6, the reference light 3 passes through the cube half mirror 7 and the glass bar 10, and vertically enters the reference mirror 5. On the other hand, the measurement beam 4 is transmitted through the cube half mirror 7 and the glass bar 10, is reflected on the surface of the wafer 16, and is perpendicularly incident on the reference mirror 5. The reference beam 3 and the measurement beam 4 reflected by the reference mirror 5 return to the original optical path again, are reflected by the cube half mirror 7, pass through the lens 8 and the glass bar 11, overlap on the linear sensor 9, and interfere with each other. Generates stripes. Here, the reference beam 3 includes the height and tilt information of the wafer 16. Therefore, the linear sensor 9
By detecting the pitch and phase change of the above interference fringes, the inclination and height of the wafer 16 can be known. That is, when the wafer 16 moves up and down, the phase of the interference fringes changes, and when the wafer 16 is tilted, the pitch of the interference fringes changes.
本実施例のような干渉計測では、干渉光路で空気のゆ
らぎ、即ち、温度，圧力，湿度のむらが生じると空気の
屈折率が変化し、干渉縞のピッチ、および、位相に影響
を及ぼし計測誤差となる。従来、これらを防止する方法
として干渉光路をカバーで覆うという方法があった。し
かし、カバーで覆った場合、干渉ビームの入出射端を開
放とした場合には、圧力や温度変化に対応できず、ま
た、カバーの両端をガラス等でふさいだ場合は内部の空
気の熱交換が十分できず、経時的な温度安定化が図れな
いという問題があった。第１図におけるガラスバー10お
よび11は、従来技術の問題を解決するために干渉光路中
に挿入したものである。ガラスバー10,11の挿入により
空気の温度や圧力、湿度変化が、直接、干渉光路に作用
せず、空気のゆらぎの影響を除去できる。ガラスバー1
0,11の材質としては、温度変化の少ない環境で使用する
場合は一般的な光学ガラス、例えば、BK7等で十分効果
があるが、温度変化が比較的大きい環境で使用する場合
は、温度変化に対する光路長の変化がほとんどないアサ
ーマルガラス（Athermal glass）、例えば、HOYA社のAT
C1,ATF2,ATF4等を使用すればよい。In the interference measurement as in the present embodiment, when the fluctuation of the air in the interference optical path, that is, the unevenness of the temperature, pressure, and humidity occurs, the refractive index of the air changes, which affects the pitch and phase of the interference fringes, and causes a measurement error. Becomes Conventionally, there has been a method of preventing such interference by covering the interference optical path with a cover. However, if it is covered with a cover, if the input / output end of the interference beam is open, it cannot cope with pressure and temperature changes, and if both ends of the cover are covered with glass, etc. However, there has been a problem that the temperature cannot be stabilized over time. Glass bars 10 and 11 in FIG. 1 have been inserted into the interference light path to solve the problems of the prior art. By inserting the glass bars 10 and 11, changes in air temperature, pressure, and humidity do not directly affect the interference optical path, and the effects of air fluctuations can be eliminated. Glass bar 1
As for the materials 0 and 11, a general optical glass, for example, BK7, is sufficiently effective when used in an environment with a small temperature change. Athermal glass with almost no change in the optical path length with respect to light, such as HOYA AT
C1, ATF2, ATF4, etc. may be used.
本発明は、互いに光路が異なる参照光と測定光とのそ
れぞれの光路を含む領域に、参照光及び測定光のそれぞ
れに対して透明な固体物質を挿入したので、空気の温度
や圧力、湿度変化が、直接干渉光路に作用せず、参照光
と測定光との光路長が互いに変動することがなくなり、
高精度な干渉計計測が可能となった。また温度変化が比
較的大きい環境での干渉計測では、温度変化に対して光
路長変化がほとんどないアサーマルガラスを干渉光路中
に挿入したので、温度的に悪い環境でも高精度な干渉計
測が可能となった。According to the present invention, since a solid substance transparent to each of the reference light and the measurement light is inserted into a region including the respective optical paths of the reference light and the measurement light having different optical paths, the temperature, pressure, and humidity of air change. However, it does not act directly on the interference optical path, the optical path lengths of the reference light and the measurement light do not fluctuate with each other,
Highly accurate interferometer measurement is now possible. In addition, in an interferometric measurement in an environment where the temperature change is relatively large, an athermal glass that has almost no change in the optical path length with respect to the temperature change is inserted into the interference light path, enabling high-precision interference measurement even in an environment with poor temperature. became.
第１図は本発明の一実施例で露光装置においてウェハの
チップ毎の高さと傾きを干渉を用いて計測する装置の説
明図である。 １……レーザ源 ３……参照光 ４……測定光 ９……光電変換素子 10、11……ガラスバーFIG. 1 is an explanatory view of an apparatus for measuring the height and inclination of each chip of a wafer using interference in an exposure apparatus according to an embodiment of the present invention. 1 ... Laser source 3 ... Reference light 4 ... Measurement light 9 ... Photoelectric conversion element 10, 11 ... Glass bar
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭57−173704（ＪＰ，Ａ) 特開 昭62−81505（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01B 9/00 - 9/10 G01B 11/00 - 11/30 H01L 21/30────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-173704 (JP, A) JP-A-62-81505 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) G01B 9/00-9/10 G01B 11/00-11/30 H01L 21/30
Claims (2)
の光路を含む領域に、前記参照光及び前記測定光に対し
て透明な固体物質を挿入し、前記参照光と前記測定光と
を共に前記固体物質中を透過させることを特徴とする干
渉光学系。1. A solid substance transparent to the reference light and the measurement light is inserted into a region including the respective optical paths of the reference light and the measurement light having different optical paths, and the reference light and the measurement light are separated from each other. An interference optical system, both transmitting through the solid substance.
及び／又は傾きを計測する干渉光学系を備えた露光装置
であって、前記干渉光学系の光路の異なる参照光と測定
光とのそれぞれの光路を含む領域に、前記参照光及び前
記測定光に対して透明な固体物質を挿入し、前記参照光
と前記測定光とを共に前記固体物質中を透過させること
を特徴とする干渉光学系を備えた露光装置。2. An exposure apparatus comprising an interference optical system for measuring a height and / or a tilt of a sample by causing a reference light and a measurement light to interfere with each other, wherein the reference light having a different optical path from the interference optical system is measured. In a region including respective optical paths of light, a solid material transparent to the reference light and the measurement light is inserted, and both the reference light and the measurement light are transmitted through the solid material. Exposure apparatus with interference optical system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2053596A JP2810194B2 (en) | 1990-03-07 | 1990-03-07 | Interference optical system and exposure apparatus having the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2053596A JP2810194B2 (en) | 1990-03-07 | 1990-03-07 | Interference optical system and exposure apparatus having the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03255902A JPH03255902A (en) | 1991-11-14 |
| JP2810194B2 true JP2810194B2 (en) | 1998-10-15 |
Family
ID=12947263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2053596A Expired - Fee Related JP2810194B2 (en) | 1990-03-07 | 1990-03-07 | Interference optical system and exposure apparatus having the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2810194B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57173704A (en) * | 1981-04-20 | 1982-10-26 | Nippon Telegr & Teleph Corp <Ntt> | Highly stable interferometer |
| JPS6281505A (en) * | 1985-10-07 | 1987-04-15 | Omron Tateisi Electronics Co | Wave-guiding type optical displacement sensor |
-
1990
- 1990-03-07 JP JP2053596A patent/JP2810194B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03255902A (en) | 1991-11-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |