JPH01173680A - Excimer laser apparatus - Google Patents
Excimer laser apparatusInfo
- Publication number
- JPH01173680A JPH01173680A JP33178787A JP33178787A JPH01173680A JP H01173680 A JPH01173680 A JP H01173680A JP 33178787 A JP33178787 A JP 33178787A JP 33178787 A JP33178787 A JP 33178787A JP H01173680 A JPH01173680 A JP H01173680A
- Authority
- JP
- Japan
- Prior art keywords
- mirror
- front mirror
- excimer laser
- face
- laser chamber
- 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
- 230000010355 oscillation Effects 0.000 claims description 14
- 238000001228 spectrum Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 11
- 239000000463 material Substances 0.000 description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000004075 alteration Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Classifications
-
- 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
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
- H01S3/082—Construction or shape of optical resonators or components thereof comprising three or more reflectors defining a plurality of resonators, e.g. for mode selection or suppression
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (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〕
本発明もよ、縮小投影露光装置の光源として用いるエキ
シマレーザ装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention also relates to an excimer laser device used as a light source of a reduction projection exposure apparatus.
（従来の技術）
エキシマレーザ光は、例えばＫｒＦレーザ光ではその波
長が２４８．４ｎｎ＋と短いこと、同じ解椴度なら水銀
ランプのｇ線やｉ線に比べて焦点深度が深いこと、レン
ズの開口数が小さくてすみ、露光領域を大きくできるこ
と、大きなパワーが得られること、等の利点から半導体
Ｍ２Ｃ用の縮小投影露光装置の光源として多用されるよ
うになってきている。(Prior art) Excimer laser light, for example KrF laser light, has a short wavelength of 248.4 nn+, has a deeper focal depth than the g-line and i-line of a mercury lamp at the same resolution, and has a lens aperture. Due to the advantages of being small in number, allowing a large exposure area, and being able to obtain large power, they are increasingly being used as a light source in reduction projection exposure apparatuses for semiconductor M2C.
ところが、エキシマレーザ光はその波長が短いため、こ
の波長を透過する材料が石英、 ＣａＦ２およびＭｑＦ
２Ｌかなく、均一性および加工稍度の点でレンズ素材と
しては石英しか用いることができない。このため、色収
差補正をした縮小投影レンズの設計が不可能となる。し
たがって、この色収差が無視し得る程度状で狭帯域化す
る必要がある。However, since the wavelength of excimer laser light is short, the materials that transmit this wavelength are quartz, CaF2, and MqF.
2L, and in terms of uniformity and processing precision, only quartz can be used as the lens material. This makes it impossible to design a reduction projection lens with chromatic aberration correction. Therefore, it is necessary to narrow the band so that this chromatic aberration can be ignored.
そこで、レーザチャンバ内で発生させたエキシマレーザ
光をレーザチャンバの両側に配置したリアミラーとフロ
ントミラーにより共振させ、さらにその共振回路中に配
置した波長選択素子により狭帯域化する構造のエキシマ
レーザ装置が縮小投影露光装置の光源として用いられて
いる。Therefore, an excimer laser device has a structure in which the excimer laser light generated in the laser chamber is resonated by a rear mirror and a front mirror placed on both sides of the laser chamber, and the band is narrowed by a wavelength selection element placed in the resonant circuit. It is used as a light source for reduction projection exposure equipment.
この場合、フロントミラーの反射率を高くすると、共振
回路中におけるレーザビームの折り返し数が多くなり、
光強度の高い波長でパワーが集中するため、波長選択素
子の設計値よりも線幅を狭くすることができる。しかし
、レーザパワーが減少してしまうという矛盾が生じる。In this case, increasing the reflectance of the front mirror increases the number of times the laser beam is turned back in the resonant circuit.
Since the power is concentrated at wavelengths with high optical intensity, the linewidth can be made narrower than the designed value of the wavelength selection element. However, a contradiction arises in that the laser power decreases.
従って、適切な線幅とレーザパワーを得るためには、フ
ロントミラーの反則率の適当な範囲が存在する。この反
射率Ｒの範囲は１≦Ｒ≦４９％であることが本発明等の
実験によって判明している。Therefore, in order to obtain an appropriate line width and laser power, there is an appropriate range of front mirror fouling rate. It has been found through experiments in the present invention that the range of reflectance R is 1≦R≦49%.
ここで、エキシマレーザの光学部品として用いられてい
る合成石英、ＣａＦ２ 、ＭｇＦ２等はコーティング無
しのもので片面的４％の表面反射率が１ｑられる。従っ
て、上記材料でフロントミラーを構成し、かつ両面をコ
ーティングしなければ、両面で４％ずつ合計的８％の反
射率がｔｑられ、上記の１≦Ｒ≦４９％の条件に合うフ
ロントミラーとして使用することができる。Here, the synthetic quartz, CaF2, MgF2, etc. used as the optical parts of the excimer laser are uncoated and have a surface reflectance of 1q of 4% on one side. Therefore, if the front mirror is made of the above material and both sides are not coated, the reflectance will be tq of 4% on both sides for a total of 8%, and the front mirror will meet the above condition of 1≦R≦49%. can be used.
（発明が解決しようとする問題点）
ところが、上記のように片面ずつ約４％の反射率を有す
るフロントミラーをそのま法相込んだ場合、このフロン
トミラーの２つの反射面間での干渉が起り、第５図のス
ペクトル図に示すように発振波長のピークが多数説われ
、これを狭帯域化したとしても第６図のスペクトル図に
示すような波形となった。しかも、この場合の発振波長
のピークは極めて近接しているために、通常使用されて
いる分光装置では識別することが困難である。このため
、分光装置の検出結果によって発振波長を制御するよう
に構成したとしても、その結ｒＡ得られる波長は不安定
となり、安定した波長のエキシマレーザ光が１ｑられな
いという問題がある。(Problem to be Solved by the Invention) However, when a front mirror having a reflectance of approximately 4% on each side is directly inserted as described above, interference occurs between the two reflecting surfaces of the front mirror. , as shown in the spectrum diagram of FIG. 5, there were many peaks of oscillation wavelength, and even if the peaks were narrowed, the waveform would be as shown in the spectrum diagram of FIG. 6. Furthermore, since the peaks of the oscillation wavelengths in this case are extremely close to each other, it is difficult to distinguish them using a commonly used spectroscopic device. Therefore, even if the configuration is such that the oscillation wavelength is controlled based on the detection result of the spectrometer, the wavelength obtained by the resultant rA becomes unstable, and there is a problem that 1q of excimer laser light of a stable wavelength cannot be obtained.
本発明の目的は、安定した発振出力が香られるエキシマ
レーザ装置を提供することにある。An object of the present invention is to provide an excimer laser device with stable oscillation output.
本発明では、フロントミラーとして片面が部分反射、他
方の片面が無反射のミラーを用いることにより、上記の
目的を達成している。In the present invention, the above object is achieved by using a mirror with one side partially reflective and the other side non-reflective as a front mirror.
フロントミラーの片面を無反射とすることにより、他方
の片面との間での干渉は生じなくなる。By making one side of the front mirror non-reflective, no interference occurs between the front mirror and the other side.
この結果、発振波長のピークは１つになり、安定した発
振出力をｔｑることができる。As a result, the oscillation wavelength has one peak, and stable oscillation output can be achieved.
（実施例〕
第１図は本発明の一実施例を示す構成図であり、レーザ
チャンバ１内で発生されたエキシマレーザ光は、ウィン
ドウ２，３を介してレーザチャンバ１の両側に配置され
たリアミラー４とフロントミラー５により：ｌ（振し、
この共振回路中のレーザチャンバ１とリアミラー４との
間に挿入された波長選択素子６によって狭帯域化された
後、フロントミラー５から出射される。(Embodiment) FIG. 1 is a configuration diagram showing an embodiment of the present invention, in which excimer laser light generated within a laser chamber 1 is arranged on both sides of the laser chamber 1 via windows 2 and 3. By rear mirror 4 and front mirror 5: l (shaking,
After being narrowed by the wavelength selection element 6 inserted between the laser chamber 1 and the rear mirror 4 in this resonant circuit, the light is emitted from the front mirror 5.
ここで、リアミラー４は反射率Ｒが８５９９％の全面反
射のミラーで構成されている。また、フロントミラー５
はレーザチャンバ側の面Ｂの反射率Ｒが１≦Ｒ≦４９％
の部分反射、その反対の而Ａが無反射面のミラーで構成
され、しかもＡ面はレーザビーム断面に対して所定角度
の傾お１を有している。Here, the rear mirror 4 is composed of a full-surface reflective mirror with a reflectance R of 8599%. Also, front mirror 5
The reflectance R of surface B on the laser chamber side is 1≦R≦49%
, and its opposite, A, is composed of a mirror with a non-reflecting surface, and the A surface has an inclination of a predetermined angle 1 with respect to the laser beam cross section.
従って、フロントミラー５の８面側から入射したレーザ
ビームは透過し、８面側に戻ることはない。すなわち、
フロントミラー５のＡ面と８面との間での干渉は生じな
くなる。しかも、Ａ面がビーム断面に対して傾斜してい
るために、Ａ面で若干の反射が生じたとしてもその反射
光がウィンドウ２を介してレーザチャンバ１内に戻るこ
とはない。これによって、フロンドラ−５のＡ面と８面
での干渉をほぼ完全になくすことができ、第２図のスペ
クトル図に示すような発振波長とすることができ、これ
をさらに狭帯域化することによって第３図に示すように
１つのピークの′３１振波長に絞ることが可能になる。Therefore, the laser beam incident on the 8th surface side of the front mirror 5 is transmitted and does not return to the 8th surface side. That is,
No interference occurs between the A side and the 8th side of the front mirror 5. Moreover, since the A plane is inclined with respect to the beam cross section, even if some reflection occurs at the A plane, the reflected light will not return into the laser chamber 1 through the window 2. As a result, interference between the A and 8 surfaces of Frondra-5 can be almost completely eliminated, and the oscillation wavelength can be set as shown in the spectrum diagram in Figure 2, which can be further narrowed. As a result, it becomes possible to narrow down the wavelength to a single peak '31 wavelength, as shown in FIG.
なお、フロントミラー５のＡ面に設けた傾斜は精度を上
げるために設けたものであり、Ａ面を無反射面とするだ
けでも８面との間の干渉を防止できることは言うまでも
ない。また、ウィンドウ２゜３についてもレーザガスと
接触しない面を無反射面とし、かつ傾斜を付けることに
より、このウィンドウ２．３の両面で生じる不要な干渉
を防止し、さらに良好なスペクトル分布の波長を１！？
ることができる。なお、このウィンドウ２，３はレーザ
ガスを隔離するものであるため、レーザガス中のＦ２に
耐え得るフッ化物（ＣａＦ２ 、Ｍ（？Ｆ２ ）の材料
が用いられる。Note that the slope provided on the A surface of the front mirror 5 is provided to improve accuracy, and it goes without saying that interference with the 8 surfaces can be prevented by simply making the A surface a non-reflective surface. In addition, by making the surface of the window 2.3 that does not come into contact with the laser gas a non-reflective surface and slanting it, unnecessary interference that occurs on both sides of the window 2.3 can be prevented, and wavelengths with a better spectral distribution can be obtained. 1! ?
can be done. Note that since the windows 2 and 3 are for isolating the laser gas, a material such as fluoride (CaF2, M(?F2)) is used that can withstand F2 in the laser gas.
さらに、波長選択素子６はファブリペローエタロンを２
枚重ね合セたもので＠成されるが、この波長選択素子６
においても反射が不要な面は無反射面としたり、傾斜を
付けることにより、さらに効率良く必要とする狭帯域エ
キシマレーザ光を得ることができる。Furthermore, the wavelength selection element 6 has two Fabry-Perot etalons.
This wavelength selection element 6 is formed by stacking two layers.
Also, by making surfaces that do not require reflection non-reflecting or slanting them, the necessary narrow band excimer laser light can be obtained more efficiently.
一方、フロントミラー５は第４図の他の実施例に示すよ
うに第１図のウィンドウ２を兼用させるように構成して
もよい。この場合、反射面は汚れる心配のない外側に配
置するのが望ましり。On the other hand, the front mirror 5 may be configured to double as the window 2 in FIG. 1, as shown in another embodiment shown in FIG. In this case, it is desirable to place the reflective surface on the outside where it will not get dirty.
以上のように本発明においては、フロントミラー片面は
無反射面としたため、フロントミラーの両面間で生じて
いた干渉を防ぐことができる。この結果、発振波長のピ
ークを安定的に絞ることが可能となり、投影露光装置に
おいてはその解像力をさらに向上さゼることかできると
いう効果がある。As described above, in the present invention, since one side of the front mirror is a non-reflecting surface, interference that occurs between both sides of the front mirror can be prevented. As a result, it becomes possible to stably narrow down the peak of the oscillation wavelength, which has the effect of further improving the resolution of the projection exposure apparatus.
第１図は本発明の一実施例を示す構成図、第２図は実施
例における中程度に狭帯域化したときの発振波長スペク
トルを示すスペクトル図、第３図は所望の幅に狭帯域化
した後の発振波長スペクトルを示すスペクトル図、第４
図は本発明の他の実施例を示ず構成図、第５図は従来袋
Ｕにおける中程度に狭帯域化したときの発振波長スペク
トルを承りスペクトル図、第６図は従来装置における所
望の幅に狭帯域化した後の発振波長スペクトルを示すス
ペクトル図である。
１・・・レーザヂャンバ、２，３・・・ウィンドウ、４
・・・リアミラー、５・・・フロントミラー、６・・・
波長選択素子。
第１図
一→−波長
第２図
□ボ５隨
第３図
一一肢長
−−〉皮長Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a spectrum diagram showing the oscillation wavelength spectrum when the band is narrowed to a moderate level in the embodiment, and Fig. 3 is a spectrum diagram showing the oscillation wavelength spectrum when the band is narrowed to a desired width. Spectrum diagram showing the oscillation wavelength spectrum after
The figure shows the configuration of another embodiment of the present invention, FIG. 5 is a spectrum diagram showing the oscillation wavelength spectrum when the band is narrowed to a medium level in the conventional bag U, and FIG. 6 is a spectrum diagram showing the desired width in the conventional device. FIG. 2 is a spectrum diagram showing an oscillation wavelength spectrum after narrowing the band. 1... Laser chamber, 2, 3... Window, 4
...Rear mirror, 5...Front mirror, 6...
Wavelength selection element. Figure 1 1 → - Wavelength Figure 2 □ Bo 5 Figure 3 11 Limb length --> Skin length
Claims (3)
光をレーザチャンバの両側に配置したリアミラーとフロ
ントミラーにより共振させ、さらにその共振回路中に配
置した波長選択素子により狭帯域化して出力するエキシ
マレーザ装置において、前記フロントミラーとして、片
面が部分反射、他方の片面が無反射のミラーを用いたこ
とを特徴とするエキシマレーザ装置。(1) An excimer laser device that causes excimer laser light generated in a laser chamber to resonate with a rear mirror and a front mirror placed on both sides of the laser chamber, and further outputs a narrow band using a wavelength selection element placed in the resonant circuit. An excimer laser device characterized in that, as the front mirror, a mirror is used in which one side is partially reflective and the other side is non-reflective.
ザ光の発振ビーム断面に対して所定角度の傾斜を有して
いることを特徴とする特許請求の範囲第（１）項記載の
エキシマレーザ装置。(2) The excimer laser device according to claim (1), wherein the non-reflection surface of the front mirror has an inclination of a predetermined angle with respect to the oscillation beam cross section of the excimer laser light.
１≦Ｒ≦４９％に設定したことを特徴とする特許請求の
範囲第（１）項記載のエキシマレーザ装置。(3) The excimer laser device according to claim (1), wherein the reflectance R of the partial reflection surface of the front mirror is set to 1≦R≦49%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62331787A JP2662963B2 (en) | 1987-12-26 | 1987-12-26 | Narrow band laser device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62331787A JP2662963B2 (en) | 1987-12-26 | 1987-12-26 | Narrow band laser device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01173680A true JPH01173680A (en) | 1989-07-10 |
| JP2662963B2 JP2662963B2 (en) | 1997-10-15 |
Family
ID=18247633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62331787A Expired - Lifetime JP2662963B2 (en) | 1987-12-26 | 1987-12-26 | Narrow band laser device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2662963B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020098814A (en) * | 2018-12-17 | 2020-06-25 | 住友重機械工業株式会社 | Optical resonator |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62155326U (en) * | 1986-03-25 | 1987-10-02 |
-
1987
- 1987-12-26 JP JP62331787A patent/JP2662963B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62155326U (en) * | 1986-03-25 | 1987-10-02 |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2020098814A (en) * | 2018-12-17 | 2020-06-25 | 住友重機械工業株式会社 | Optical resonator |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2662963B2 (en) | 1997-10-15 |
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