JPH02271689A - Frequency stabilizer for excimer laser - Google Patents
Frequency stabilizer for excimer laserInfo
- Publication number
- JPH02271689A JPH02271689A JP9374889A JP9374889A JPH02271689A JP H02271689 A JPH02271689 A JP H02271689A JP 9374889 A JP9374889 A JP 9374889A JP 9374889 A JP9374889 A JP 9374889A JP H02271689 A JPH02271689 A JP H02271689A
- Authority
- JP
- Japan
- Prior art keywords
- wavelength
- excimer laser
- laser light
- light source
- frequency
- 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.)
- Pending
Links
- 239000003381 stabilizer Substances 0.000 title claims 2
- 238000005259 measurement Methods 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 3
- 230000010355 oscillation Effects 0.000 claims description 2
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 abstract description 12
- 239000013307 optical fiber Substances 0.000 abstract description 6
- 230000003595 spectral effect Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 5
- 230000000087 stabilizing effect Effects 0.000 description 4
- 239000000835 fiber Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000012806 monitoring device Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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
- G03F7/70008—Production of exposure light, i.e. light sources
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/139—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
- H01S3/1394—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length by using an active reference, e.g. second laser, klystron or other standard frequency source
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、露光装置等の光源として利用されるエキシマ
レーザに関するものであり、さらに詳しくは発振したエ
キシマレーザ光の発振周波数を安定化させるための周波
数安定化装置に関するのものである。[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an excimer laser used as a light source for exposure equipment, etc., and more specifically, to stabilize the oscillation frequency of oscillated excimer laser light. The present invention relates to a frequency stabilizing device.
（従来の技術）
例えば、リソグラフィ装置において使用されるエキシマ
レーザは、装置内の縮小投影レンズが色消しではないの
で、結像面の安定性、倍率、重ね合わせ精度などの性能
を保持するためには、波長域が狭くかつ中心波長が安定
している必要がある。(Prior art) For example, in an excimer laser used in a lithography apparatus, since the reduction projection lens in the apparatus is not achromatic, it is necessary to maintain performance such as stability of the image plane, magnification, and overlay accuracy. requires a narrow wavelength range and a stable center wavelength.
このうち、波長の狭帯域化の技術としては、第３図に示
すように、エタロン１、回折格子２、プリズム３などが
利用された各種の発振器構造が提案されている。Among these, as a technique for narrowing the wavelength band, various oscillator structures using an etalon 1, a diffraction grating 2, a prism 3, etc., as shown in FIG. 3, have been proposed.
一方、エキシマレーザの中心波長を安定化させるための
技法としては、共振器において、何らかの分光手段で波
長をモニターして、エタロン、回折格子の入射角度ある
いは圧力を調整する必要がある。このような波長モニタ
ー装置としては、第４図に示すような分光器あるいはエ
タロンと、イメージセンサ４とを組み合わせたものが使
用されており、第５図に示すように、分光器やエタロン
によるピーク波形の中心位置ずれに基づきエキシマレー
ザの中心周波数の位置ずれを補正すべく波長制御を行う
構成のものが知られている。On the other hand, as a technique for stabilizing the center wavelength of an excimer laser, it is necessary to monitor the wavelength using some kind of spectroscopic means in the resonator and adjust the incident angle or pressure of the etalon or diffraction grating. As such a wavelength monitoring device, a combination of a spectroscope or etalon and an image sensor 4 as shown in Fig. 4 is used. A configuration is known in which wavelength control is performed to correct a shift in the center frequency of an excimer laser based on a shift in the center position of the waveform.
（発明が解決しようとする課題）
ここに、このような波長モニター装置におけるモニター
系の誤差要因としては、気圧変化および機械的な不安定
性に起因したピーク位置ずれがある。このうち、気圧変
化による影響は、モニター系を密閉することによって解
消できる。しかし、もう一方の機械的な不安定性に起因
した波長ピーク位置のずれについては、これを解消する
適切な方法が無く、このために、正確な波長測定ができ
ず、しいては正確な波長制御ができないという問題があ
る。(Problems to be Solved by the Invention) Here, as a cause of error in the monitor system in such a wavelength monitor device, there is a peak position shift due to changes in atmospheric pressure and mechanical instability. Of these, the effects of atmospheric pressure changes can be eliminated by sealing the monitor system. However, as for the shift in the wavelength peak position caused by the other mechanical instability, there is no appropriate method to resolve this, and for this reason, accurate wavelength measurement is not possible, and accurate wavelength control is not possible. The problem is that it is not possible.
本考案の課題は、この点に鑑みて、波長モニター系の機
械的な不安定性に起因して波長制御が不確実となること
を防止することの可能となったエキシマレーザの周波数
安定化装置を実現することにある。In view of this point, the problem of the present invention is to develop an excimer laser frequency stabilization device that makes it possible to prevent wavelength control from becoming uncertain due to mechanical instability of the wavelength monitoring system. It is about realization.
（課題を解決するための手段）
上記の課題を解決するために、本発明においては、主光
源であるエキシマレーザ光源の他に、周波数安定型のレ
ーザ光源を参照用光源として用い、これら両者を光ファ
イバー等の光伝送手段を用いて、エタロン等の分光素子
に入射し、これによって得られる参照用光源の分光像に
基づき、エキシマレーザ光の波長測定結果を補正して正
確なエキシマレーザ光の波長データを得て、この波長デ
ータに基づきエキシマレーザの中心周波数が安定するよ
うに制御している。(Means for Solving the Problems) In order to solve the above problems, in the present invention, in addition to the excimer laser light source that is the main light source, a frequency-stable laser light source is used as a reference light source, and both of these are used as a reference light source. Using a light transmission means such as an optical fiber, the light enters a spectroscopic element such as an etalon, and based on the spectral image of the reference light source obtained, the wavelength measurement result of the excimer laser light is corrected to obtain the accurate wavelength of the excimer laser light. Data is obtained, and control is performed to stabilize the center frequency of the excimer laser based on this wavelength data.
（実施例） 以下に図面を参照して本発明の詳細な説明する。(Example) The present invention will be described in detail below with reference to the drawings.
第１図には本実施例の周波数安定化装置の全体ブロック
図を示す。図において、１１はエキシマレーザ発振器で
あり、この発振器の波長制御素子１１ａは、中央処理ユ
ニット１２の制御下にある制御回路１３によって制御さ
れる。エキシマレーザ発振器１１の前面にはビームスプ
リッタ１４が配置され、このビームスプリッタによって
主光源であるエキシマレーザ光の一部が反射される。反
射光は、ソレノイドシャッタ１５および集光レンズ１６
を順次に通って第１の光フアイバースリーブ１７に入射
される。FIG. 1 shows an overall block diagram of the frequency stabilizing device of this embodiment. In the figure, 11 is an excimer laser oscillator, and a wavelength control element 11a of this oscillator is controlled by a control circuit 13 under the control of a central processing unit 12. A beam splitter 14 is arranged in front of the excimer laser oscillator 11, and a part of the excimer laser light, which is the main light source, is reflected by this beam splitter. The reflected light passes through the solenoid shutter 15 and the condensing lens 16.
The light passes through the optical fiber sleeve 17 in sequence and enters the first optical fiber sleeve 17.
一方、２１は参照光源としての周波数安定型のＨｅ−Ｎ
ｅレーザ発振器であり、ここから発射された周波数の安
定した参照レーザ光は、その前面に配置したシャッター
２２を通って第２の光フアイバースリーブ２３に入射さ
れる。第１および第２のスリーブ１７．２３に入射され
たエキシマレーザ反射光および参照光は、光伝送路であ
る二股の石英ファイバー２４を通って、同一の射出側ス
イリーブ２５に伝送される。この射出側スリーブ２５の
出射側は圧力密閉容器２６内に位置しており、このスリ
ーブ２５から出射した光は、広がりながら分光素子であ
るエタロン２７に入射する。On the other hand, 21 is a frequency-stable He-N as a reference light source.
The e-laser oscillator is an e-laser oscillator, and a reference laser beam with a stable frequency emitted from the e-laser oscillator is incident on the second optical fiber sleeve 23 through a shutter 22 disposed in front of the e-laser oscillator. The excimer laser reflected light and the reference light incident on the first and second sleeves 17.23 are transmitted to the same exit-side sleeve 25 through the bifurcated quartz fiber 24, which is an optical transmission path. The exit side of this exit-side sleeve 25 is located within a pressure-tight container 26, and the light emitted from this sleeve 25 enters an etalon 27, which is a spectroscopic element, while spreading.
本例では、エタロン２７として、２４９ ｎｍと６３３
ｎｍにおいて約９０％の反射率を有するものを使用した
。このエタロン２７から得られた干渉波形は、２５μｍ
幅のフォトダイオードからなる１次元イメージセンサ２
８で受光され、受光された情報がセンサ駆動およびデー
タ取込み回路２９に取り込まれる。この回路２９におい
て得られた情報は、中央処理ユニッ）１２に供給される
。中央処理ユニット１２では供給された情報に基づき、
制御回路１３を介してエキシマレーザ発振器の周波数制
御素子１１ａを駆動して、エキシマレーザの中心波長が
安定化する方向に制御する。In this example, the etalon 27 is 249 nm and 633 nm.
A material having a reflectance of about 90% at nm was used. The interference waveform obtained from this etalon 27 is 25 μm
One-dimensional image sensor 2 consisting of a wide photodiode
The light is received at 8, and the received information is taken into the sensor drive and data acquisition circuit 29. The information obtained in this circuit 29 is supplied to the central processing unit (12). Based on the supplied information, the central processing unit 12
The frequency control element 11a of the excimer laser oscillator is driven via the control circuit 13 to control the center wavelength of the excimer laser in a direction that stabilizes it.
すなわち、データ取込み回路２９においては、第２図に
示すような双方のレーザの波形情報が得られる。中央処
理装置１２においては、得られた情報にうち、周波数安
定型レーザのエタロン干渉波形Ｂを基準として、エキシ
マレーザのエタロン干渉波形へのデータを補正して正確
な波長計測を行い、これによって得られる結果に基づき
、波長制御素子１１ａを制御して、エキシマレーザ光の
中心波長を安定化させるようにしている。That is, in the data acquisition circuit 29, waveform information of both lasers as shown in FIG. 2 is obtained. In the central processing unit 12, based on the obtained information, data on the etalon interference waveform of the excimer laser is corrected based on the etalon interference waveform B of the frequency stabilized laser, and accurate wavelength measurement is performed. Based on the results obtained, the wavelength control element 11a is controlled to stabilize the center wavelength of the excimer laser beam.
ここに、本例においては、エキシマレーザ光とＨｅ−Ｎ
ｅレーザ光を同時に取り込むと、見かけ上エタロン２７
のフィネスが低下するので、上記のシャッター１５．２
２を交互に開閉することによって、これらのレーザ光を
交互に取り込むようにしている。また、ファイバースリ
ーブ２５とイメージセンサ２８との距離を３００ないし
４００ｍｍにとり、エタロン２７のギャップを約１ｍｍ
に設定しである。これにより、イメージセンサの１チヤ
ンネル当たり（２５μｍ）の逆分散が０゜３ｐｍ程度に
なるので、ｌｐｍ以内の波長制御が可能となっている。Here, in this example, excimer laser light and He-N
When e-laser light is taken in at the same time, it appears that the etalon 27
Since the finesse of
By alternately opening and closing 2, these laser beams are taken in alternately. Also, the distance between the fiber sleeve 25 and the image sensor 28 is set to 300 to 400 mm, and the gap between the etalon 27 is set to about 1 mm.
It is set to . As a result, the inverse dispersion per channel (25 μm) of the image sensor is approximately 0°3 pm, so wavelength control within 1 pm is possible.
（発明の効果）
以上説明したように、本発明のエキシマレーザの周波数
安定化装置においては、参照光源として周波数安定型の
レーザ発振器から発振したレーザ光の波長に基づき、エ
キシマレーザ光をモニターして得たエキシマレーザ光の
波長測定値を補正するようにしている。したがって、本
発明によれば、エキシマレーザ光のモニター系の機械的
な不安定性に起因してエキシマレーザ光の波長測定値に
誤差が生じたとしても、この誤差が参照光源から得られ
る測定値によって補償されるので、常に正確な波長測定
値を得ることができ、以て正確な波長制御を行うことが
可能になる。(Effects of the Invention) As explained above, in the excimer laser frequency stabilization device of the present invention, the excimer laser light is monitored based on the wavelength of the laser light oscillated from a frequency-stable laser oscillator as a reference light source. The wavelength measurement value of the obtained excimer laser light is corrected. Therefore, according to the present invention, even if an error occurs in the measured wavelength of the excimer laser beam due to mechanical instability of the excimer laser beam monitoring system, this error can be corrected by the measured value obtained from the reference light source. Since the wavelength is compensated, accurate wavelength measurement values can be obtained at all times, making it possible to perform accurate wavelength control.
第１図は本発明のエキシマレーザの周波数安定化装置の
全体構成を示すブロック図、第２図は第１図の装置にお
けるデータ取込み回路で得られるエキシマレーザ光およ
び参照光の波形図、第３図（Ａ）ないしくＤ）はエキシ
マレーザの発振器構造をそれぞれ示す図、第４図（Ａ）
および（Ｂ）はそれぞれエキシマレーザの周波数モニタ
ー装置を示す図、第５図（Ａ）および（Ｂ）は第４図（
Ａ）および（Ｂ）に示すモニター装置で得られた波形を
示す波形図である。
符号の説明
１・−・エキシマレーザ発振器
１ａ・・・波長制御素子
２−中央処理ユニント
３・−制御回路
４−・・ビームスプリッタ
５．２２− シャッタ
６−集光レンズ
７．２３．２５−・ファイバスリーブ
１−Ｈｅ −Ｎ ｅレーザ発振器
４・−光ファイバ
ロー圧力密閉容器
７・・−エタロン
８−イメージセンサ
９−・・データ取込み装置
第１図
図面の浄書（内容に変更なし）FIG. 1 is a block diagram showing the overall configuration of the excimer laser frequency stabilizing device of the present invention, FIG. 2 is a waveform diagram of the excimer laser light and reference light obtained by the data acquisition circuit in the device of FIG. 1, and FIG. Figures (A) to D) are diagrams each showing the oscillator structure of an excimer laser, and Figure 4 (A).
and (B) are diagrams showing the excimer laser frequency monitoring device, respectively, and Figures 5 (A) and (B) are Figure 4 (
FIG. 3 is a waveform chart showing waveforms obtained by the monitoring devices shown in A) and FIG. 3B. Explanation of symbols 1 -- Excimer laser oscillator 1a -- Wavelength control element 2 -- Central processing unit 3 -- Control circuit 4 -- Beam splitter 5.22 -- Shutter 6 -- Condenser lens 7.23.25 -- -- Fiber sleeve 1 - He - N e laser oscillator 4 - Optical fiber low pressure sealed container 7 - Etalon 8 - Image sensor 9 - Data acquisition device Reprint of the drawing in Figure 1 (no changes in content)
Claims (1)
、周波数が安定しているレーザ光を発生する参照光発生
手段と、分光素子と、主光源であるエキシマレーザ光の
一部および前記参照光発生手段から発生した参照レーザ
光を前記分光素子に入射させる光伝送手段と、前記分光
素子で分光された光が入射されるイメージセンサと、こ
のイメージセンサから得られる前記参照レーザ光の周波
数測定値に基づき、同じくこのイメージセンサからえら
える前記エキシマレーザ光の周波数測定値を補正し、こ
の補正値に基づき前記エキシマレーザ光の波長が安定化
するように制御する制御手段とを有することを特徴とす
るエキシマレーザの周波数安定化装置。In an excimer laser whose oscillation frequency is narrow-band, a reference light generating means for generating a laser beam having a stable frequency, a spectroscopic element, a part of the excimer laser light serving as a main light source, and the reference light generating means are provided. A light transmission means for causing the generated reference laser beam to enter the spectroscopic element, an image sensor to which the light separated by the spectroscopic element is incident, and a frequency measurement value of the reference laser beam obtained from the image sensor, An excimer laser further comprising control means for correcting a frequency measurement value of the excimer laser light obtained from the image sensor and controlling the wavelength of the excimer laser light to be stabilized based on this correction value. frequency stabilizer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9374889A JPH02271689A (en) | 1989-04-13 | 1989-04-13 | Frequency stabilizer for excimer laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9374889A JPH02271689A (en) | 1989-04-13 | 1989-04-13 | Frequency stabilizer for excimer laser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02271689A true JPH02271689A (en) | 1990-11-06 |
Family
ID=14091046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9374889A Pending JPH02271689A (en) | 1989-04-13 | 1989-04-13 | Frequency stabilizer for excimer laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02271689A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0567821A (en) * | 1991-09-06 | 1993-03-19 | Mitsubishi Electric Corp | Wavelength monitor for narrow-band laser |
| EP1063503A1 (en) * | 1999-06-23 | 2000-12-27 | Ushio Research Institute of Technology, Inc. | Wavelength monitoring apparatus for laser light for semiconductor exposure |
-
1989
- 1989-04-13 JP JP9374889A patent/JPH02271689A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0567821A (en) * | 1991-09-06 | 1993-03-19 | Mitsubishi Electric Corp | Wavelength monitor for narrow-band laser |
| EP1063503A1 (en) * | 1999-06-23 | 2000-12-27 | Ushio Research Institute of Technology, Inc. | Wavelength monitoring apparatus for laser light for semiconductor exposure |
| US6509970B1 (en) | 1999-06-23 | 2003-01-21 | Ushio Denki Kabushiki Kaisya | Wavelength monitoring apparatus for laser light for semiconductor exposure |
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