JPH0570124B2 - - Google Patents
Info
- Publication number
- JPH0570124B2 JPH0570124B2 JP59050763A JP5076384A JPH0570124B2 JP H0570124 B2 JPH0570124 B2 JP H0570124B2 JP 59050763 A JP59050763 A JP 59050763A JP 5076384 A JP5076384 A JP 5076384A JP H0570124 B2 JPH0570124 B2 JP H0570124B2
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- projection
- air
- magnification
- space
- 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 - Lifetime
Links
- 230000003287 optical effect Effects 0.000 claims description 31
- 238000007789 sealing Methods 0.000 claims description 7
- 238000003384 imaging method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000003068 static effect Effects 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
- G03F7/70216—Mask projection systems
- G03F7/70241—Optical aspects of refractive lens systems, i.e. comprising only refractive elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/021—Mountings, adjusting means, or light-tight connections, for optical elements for lenses for more than one lens
-
- 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
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70808—Construction details, e.g. housing, load-lock, seals or windows for passing light in or out of apparatus
- G03F7/70825—Mounting of individual elements, e.g. mounts, holders or supports
-
- 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
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
-
- 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
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
- G03F7/70883—Environment aspects, e.g. pressure of beam-path gas, temperature of optical system
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Epidemiology (AREA)
- Public Health (AREA)
- Life Sciences & Earth Sciences (AREA)
- Atmospheric Sciences (AREA)
- Toxicology (AREA)
- Optics & Photonics (AREA)
- Lens Barrels (AREA)
Description
（発明の技術分野）
本発明は投影光学系の光学特性を簡便に補正し
得る投影光学装置に関する。
（発明の背景）
縮小投影型露光装置（以下ステツパと呼ぶ）は
近年超LSIの生産現場に多く導入され、大きな成
果をもたらしているが、その重要な性能の一つに
重ね合せマツチング精度があげられる。このマツ
チング精度に影響を与える要素の中で重要なもの
に投影光学系の倍率誤差がある。超LSIに用いら
れるパターンの大きさは年々微細化の傾向を強
め、それに伴つてマツチング精度の向上に対する
ニーズも強くなつてきている。従つて投影倍率を
所定の値に保つ必要性はきわめて高くなつてきて
いる。現在投影光学系の倍率は装置の設置時に調
整することにより倍率誤差が一応無視できる程度
になつている。しかしながら、超LSIの高密度化
に十分対応するためには、装置の稼動時における
クリーンルーム内の僅かな気圧変動等、環境条件
が変化した時の倍率誤差をも補正する必要があ
る。
従来ステツパ以外の投影光学系では投影倍率を
補正するために物体（レチクル）と投影レンズの
間隔を機械的に変化させたり、投影レンズ中のレ
ンズエレメントを光軸方向に動かしたりする方法
がとられていた。しかしステツパのように極めて
高精度な倍率設定が必要な装置に上記のように光
学部材を光軸方向に変化させるという方法を採用
すると機械的な可動部の偏心（シフト、テイル
ト）のため光軸を正しく保つたまゝ変位を与える
ことが難しい。そのため物体を含めた光学系が共
軸でなくなつてしまい、光軸に対して非対称な倍
率分布が像面上に生じてしまう欠点が生ずる。又
ウエハ上で0.05μm以下の誤差しか発生しない様
に精度良く倍率設定するためには光学部材の変化
量を偏心（シフト、テイルト）を含めて数μmな
いし1μm以下に制御する必要がありこれらの実現
には多大の困難がともなう。
（発明の目的）
本発明は、これらの欠点を除き、非対称な倍率
分布を発生することなく簡便に倍率、結像位置等
の光学特性の変動を補正し得る投影光学装置を提
供することを目的とする。
（発明の概要）
本発明にあたつて投影対物レンズの投影倍率の
変動要因の一つが大気圧変動にあることを見い出
し、圧力変動のみによつても投影倍率が無視し得
ない程度に変化する場合があることが判明した。
そこで、本発明は、投影対物レンズ内の各空気間
隔及び投影対物レンズと投影原板（レチクル）と
の間の空間並びに投影対物レンズと感光物体（ウ
エハ）との間の空間のうち、投影対物レンズ内の
レンズ面間に形成される空気室の一部または全部
を外気から遮断（密封）し、この空気室を所定の
一定圧力に制御することによつて投影対物レンズ
の倍率変動を補正実用上十分な倍率精度の維持を
可能としたものである。
このような本発明によれば、露光装置において
交換可能に取付けられる投影原板（レチクル）
や、露光及びアライメントごとに頻繁に移動する
感光物体（ウエハ）については何ら関与すること
なく投影対物レンズにおいてのみ倍率補正がなさ
れるため極めて簡単な構成である。また補正のた
めに投影対物レンズを動かすといつた機械的な動
きを必要とせず、いわば静的補正であるため、偏
心を生ずる恐れが無く結像性能を非対称に劣化さ
せることもない。
また、本発明では、投影対物レンズの製造場所
とこれを組込んだ投影露光装置の使用場所とは異
なるため、標高差等により基本的に大気圧に差が
あり、対物レンズ内部の圧力を使用場所の環境に
応じて最適とする。投影対物レンズの密封空気室
の圧力を使用場所の環境に応じて変えるために
は、圧力制御手段によつて最適圧力となるように
制御する。特に、投影対物レンズの密封空気室の
圧力を使用場所の環境に順応するよう最適圧力に
保つことは、密封空気室の内部と外部との圧力差
を小さくできるため以下の点で優れている。(1)投
影対物レングの密封空気室を構成するレンズ要素
のうち最も外側のレンズ表面が大気圧とレンズ内
部の圧力との圧力差によつて変形したり変位を生
ずる恐れが少なく、(2)また密封空気室中の気体の
リークがあつても圧力制御手段によつて最適圧力
に制御されるため倍率等の光学性能に変動を生ず
ることが少ない。
（実施例）
以下、実施例に基づいて本発明を説明する。第
１図はステツパーに用いられる投影対物レンズの
一例を示すレンズ配置図であり、この対物レンズ
によりレチクルＲ上の所定のパターンがウエハＷ
上に縮小投影される。図中にはウエハとレチクル
との軸上物点の共役関係を表わす光線を示した。
この対物レンズはレチクルＲ側から順にL1，L2，
…L14の合計14個のレンズからなり、各レンズの
間隔及びレチクルＲ、ウエハＷとの間に、レチク
ル側から順にａ，ｂ，ｃ，…，ｏの合計15個の空
気間隔が形成されている。この対物レンズの諸元
を表１に示す。但し、ｒは各レンズ面の曲率半
径、Ｄは各レンズの中心厚及び空気間隔、Ｎは各
レンズのｉ線（λ＝365.0nm）に対する屈折率を
表わし、表中左端の数字はレチクル側から順序を
表わすものとする。また、D0はレチクルＲと最
前レンズ面との間隔、D31は最終レンズ面とウエ
ハＷとの間隔を表わす。
いま、この対物レンズにおいて、空気間隔ａ，
ｂ，…ｏの気圧をそれぞれ＋137.5mmHgだけ変化
させたとすると、各空気間隔の相対屈折率は
1.00005に変化し、この時の倍率変化、及び結像
面すなわちレチクルＲとの共役面の変化は表２に
示すようになる。但し、倍率変化ΔXは、結像面
上において気圧変動がない時に光軸より5.66mm離
れた位置に結像する像点が、各空気間隔の気圧変
化後の移動量をμm単位で表わし、気圧変動が無
い場合の結像面すなわち所定のウエハ面上により
大きく投影される場合（拡大）を正符号として示
した。また、結像面の変化ΔZは軸上の結像点の
変化として示し、対物レンズから遠ざかる場合を
正符号として示した。両者の値は共にμm単位で
ある。
(Technical Field of the Invention) The present invention relates to a projection optical device that can easily correct the optical characteristics of a projection optical system. (Background of the invention) Reduction projection exposure devices (hereinafter referred to as steppers) have been introduced to many VLSI production sites in recent years and have brought great results, but one of their important performances is overlay matching accuracy. It will be done. Among the factors that affect this matching accuracy, an important one is the magnification error of the projection optical system. The size of patterns used in VLSIs is becoming smaller and smaller year by year, and the need for improved matching accuracy is also growing. Therefore, the need to maintain the projection magnification at a predetermined value has become extremely high. Currently, the magnification of the projection optical system is adjusted at the time of installation of the apparatus, so that the magnification error can be ignored. However, in order to adequately cope with the increasing density of VLSIs, it is necessary to correct magnification errors caused by changes in environmental conditions, such as slight pressure fluctuations in the clean room during equipment operation. Conventionally, in projection optical systems other than steppers, methods have been used to correct the projection magnification by mechanically changing the distance between the object (reticle) and the projection lens, or by moving the lens element in the projection lens in the optical axis direction. was. However, if the method of changing the optical member in the optical axis direction as described above is adopted for a device that requires extremely high-precision magnification setting such as a stepper, the optical axis It is difficult to apply displacement while keeping it correct. As a result, the optical system including the object is no longer coaxial, resulting in a disadvantage that a magnification distribution asymmetrical with respect to the optical axis occurs on the image plane. In addition, in order to accurately set the magnification so that an error of 0.05 μm or less occurs on the wafer, it is necessary to control the amount of change in the optical member to within a few μm or 1 μm, including eccentricity (shift, tail). Realization will involve great difficulties. (Objective of the Invention) An object of the present invention is to eliminate these drawbacks and provide a projection optical device that can easily correct variations in optical characteristics such as magnification and imaging position without causing an asymmetric magnification distribution. shall be. (Summary of the Invention) In developing the present invention, it has been discovered that one of the factors that cause variations in the projection magnification of a projection objective lens is atmospheric pressure fluctuations, and the projection magnification changes to a non-negligible extent even by pressure fluctuations alone. It turns out that there are cases.
Therefore, the present invention provides a method for reducing air gaps within the projection objective, the space between the projection objective and the projection original plate (reticle), and the space between the projection objective and the photosensitive object (wafer). For practical purposes, this method corrects magnification fluctuations of the projection objective lens by blocking (sealing) part or all of the air chamber formed between the inner lens surfaces from the outside air and controlling this air chamber to a predetermined constant pressure. This makes it possible to maintain sufficient magnification accuracy. According to the present invention, a projection original plate (reticle) replaceably mounted in an exposure apparatus
The structure is extremely simple because the magnification correction is performed only in the projection objective lens without any involvement of the photosensitive object (wafer) that frequently moves during each exposure and alignment. Further, since the correction does not require mechanical movement such as moving the projection objective lens, and is a so-called static correction, there is no risk of decentering and there is no asymmetric deterioration of imaging performance. In addition, in the present invention, since the manufacturing location of the projection objective lens is different from the usage location of the projection exposure apparatus incorporating it, there is basically a difference in atmospheric pressure due to altitude difference, etc., and the pressure inside the objective lens is used. Optimal depending on the location environment. In order to change the pressure in the sealed air chamber of the projection objective lens depending on the environment at the place of use, the pressure is controlled to an optimum pressure by a pressure control means. In particular, maintaining the pressure in the sealed air chamber of the projection objective lens at an optimal pressure to adapt to the environment of the place of use is advantageous in the following points because the pressure difference between the inside and outside of the sealed air chamber can be reduced. (1) The outermost lens surface of the lens elements constituting the sealed air chamber of the projection objective lens is unlikely to be deformed or displaced due to the pressure difference between atmospheric pressure and the pressure inside the lens; (2) Furthermore, even if there is a leak of gas in the sealed air chamber, the pressure is controlled to an optimum pressure by the pressure control means, so that optical performance such as magnification is less likely to change. (Examples) The present invention will be described below based on Examples. FIG. 1 is a lens arrangement diagram showing an example of a projection objective lens used in a stepper.
It is reduced and projected onto the top. In the figure, light rays representing the conjugate relationship between on-axis object points between the wafer and the reticle are shown.
This objective lens is L 1 , L 2 ,
It consists of a total of 14 lenses (...L 14) , and a total of 15 air gaps (a, b, c, ..., o) are formed between each lens and between the reticle R and wafer W in order from the reticle side. ing. Table 1 shows the specifications of this objective lens. However, r is the radius of curvature of each lens surface, D is the center thickness and air gap of each lens, N is the refractive index of each lens for the i-line (λ = 365.0 nm), and the numbers on the left end of the table are from the reticle side. Let it represent the order. Further, D 0 represents the distance between the reticle R and the foremost lens surface, and D 31 represents the distance between the final lens surface and the wafer W. Now, in this objective lens, the air spacing a,
If the atmospheric pressure of b,...o is changed by +137.5mmHg, the relative refractive index of each air gap is
1.00005, and the change in magnification and the change in the imaging plane, that is, the conjugate plane with the reticle R, are shown in Table 2. However, the magnification change ΔX is the amount of movement in μm of the image point, which is formed at a position 5.66 mm away from the optical axis when there is no atmospheric pressure change on the imaging plane, after the atmospheric pressure changes in each air interval, and the atmospheric pressure The positive sign indicates the case where the image is projected larger onto the image forming plane when there is no variation, that is, the predetermined wafer surface (enlargement). Further, the change in the imaging plane ΔZ is shown as a change in the imaging point on the axis, and the case where it moves away from the objective lens is shown as a positive sign. Both values are in μm.
【表】【table】
【表】
第１実施例：
上記の表２より第１空間ａ即ち、レチクルと投
影対物レンズとの空間、及び第15空間ｏ即ちウエ
ハと投影対物レンズとの空間における倍率変動は
共に正の値であり、その合計は0.043である。従
つて、投影対物レンズ内に形成される全ての空
間、即ち第２空間ｂ〜第14空間ｎを大気圧から遮
断し、一体的に密閉することによつて、これら投
影対物レンズ内の空間に帰因する倍率変化は発生
せず、第１空間ａと第15空間ｏとにより倍率変動
のみとなり、全系によつて生じ得る倍率変動の約
４％に抑えることが可能となる。
又、投影対物レンズ内に形成される全ての空間
を大気圧から遮断することによつて、結像面の変
化も1.02μmになり全系によつて生じ得る変化の
約７％に抑えられる。
第２図は表１に示した投影対物レンズの鏡筒構
造及び圧力制御手段を示す図である。対物レンズ
を構成する14個のレンズL1，L2，…，L14はそれ
ぞれ第１支持筒１、第２支持筒２、…、第14支持
筒１４によつて支持されている。これら14個の支
持筒が積み重ねられることによつて実質的に内部
鏡筒が形成され、これらは外部鏡筒２０によつて
一体的に収納支持され、押え環２１によつて固定
されている。第１レンズL1から第14レンズL14を
それぞれ支持する第１支持筒１〜第14支持筒１４
によつて13個の空気室Ｂ〜Ｎが形成されており、
これらの空気室Ｂ〜Ｎはそれぞれ第１図に示した
空気間隔ｂ〜ｎに対応している。こゝで第２レン
ズL2を支持する第２支持筒２から第13レンズを
支持する第13支持筒１３までにはそれぞれ隣接す
る空気室を連通するための貫通孔２ａ〜１３ａが
形成されている。また、対物レンズの先端に位置
する第14レンズL14を支持する第14支持筒１４は、
第14レンズL14を介して第13空気室Ｎを外気から
遮断するように第14レンズL14を気密支持し、ま
た外部鏡筒２０によつて気密支持されている。そ
して、第１レンズL1を支持する第１支持筒は第
１レンズL1を気密支持する。この気密支持のた
めにはＯ−リング等のパツキンが使用される。第
１支持筒１に形成された貫通孔１ａには管２２が
挿入されている。第１支持筒１と管２２との間に
も気密のためにパツキンが配設されている。
圧力制御装置２３は管２２を介して一体的空気
室Ｂ〜Ｎの圧力を制御する。圧力制御装置２３
は、空気室Ｂ〜Ｎの圧力を上昇させる場合には加
圧空気供給装置２４からの加圧空気を管２２を介
して空気室Ｂ〜Ｎに送り込み、これを下降させる
場合には空気室Ｂ〜Ｎ内の空気を排気装置２６を
介して排出する。圧力制御装置２３と加圧空気供
給装置２４との間には、空気室Ｂ〜Ｎに送り込む
空気を清浄にするためのフイルタ２５が配置され
ている。圧力センサー２７は空気室内の圧力を検
出するためのもので、例えば空気室Ｈの圧力を検
出する。圧力設定回路２８は投影露光装置の使用
場所の標高等に応じた大気圧を設定する。比較回
路２９は圧力センサー２７の出力信号と圧力設定
回路２８の出力信号とを比較し、両出力信号の差
又は大小関係を示す信号を発生する。圧力制御装
置２３は比較回路２９の出力信号を入力として、
圧力センサー２７と圧力設定回路２８の出力が所
定関係となる（一致する）ように空気室Ｂ〜Ｎの
圧力を制御する。
このように、空気室Ｂ〜Ｎの圧力は露光装置使
用場所の標高等に応じた大気圧に常時維持される
から投影対物レンズの倍率を精密に維持すること
が可能になる。
第２実施例：
上記表２に示された倍率変化量ΔXについて各
空間の値をグラフに示したのが第３図である。第
３図のグラフの縦軸は倍率変化量ΔX、横軸は圧
力変化量ΔPであり、図中の各直線に示した記号
は各空間に対応する。また全系における倍率変化
量ΔTxを太い実線にて示した。
上記の表２及び第３図のグラフから、全系によ
る倍率変動量Ｓ＝1.004に対して、第３空気間隔
Ｃ単独によつて生ずる倍率変動量が最も近い値で
あることが判る。従つて、この第３空気間隔Ｃの
みを密封することによつて全系の倍率変動をほぼ
補正することができる。すなわち第３空気間隔Ｃ
による倍率変動量1.164はこの空間を大気から遮
断し密封することにより零とできるから全系によ
る倍率変動との差のみが実質的な倍率変動量とな
る。従つてこの場合、実質的な倍率変動量は−
0.16であり16％に減少することが明らかである。
この補正後における全系の倍率変化ΔTx′の様子
を第３図中点線で示した。
さて、１つの空気間隔のみではなく、複数の空
気間隔を組合せて大気から遮断するよう密閉する
ことによつても大気圧変動による倍率変化を補正
することが可能である。例えば、上記の対物レン
ズにおいて、第７空気間隔ｇから第12空気間隔ｌ
までの連続する６つのレンズ間隔を大気から遮断
し一体的に密閉するならば、これら６つの空気間
隔で生ずる倍率変動の和0.935が零とできるので、
全系で生ずる倍率変動1.004との差0.069のみの小
さい値の変動に補正することができる。すなわ
ち、全系における倍率変動は6.9％にまで補正さ
れることになる。また、これら６つの空気間隔に
加えて第13空気間隔ｍをも大気から遮断し密閉す
る構成とすれば、全系における倍率変動量は−
0.067となりより良好に補正することが可能とな
る。さらに、第14空気間隔ｎをも大気から遮断し
て密閉し合計８つの密閉空間を形成することとす
れば、これら８つの空間による倍率変動の補正量
は1.063となり、全系の倍率変動量を−0.059まで
に小さく補正することが可能である。
この実施例のうち、第３空気間隔Ｃのみを大気
から遮断し密閉する構成が最も簡単であるが、こ
の第３空気間隔Ｃを密閉することによつて、結像
面の全系による変動がより大きくなる。これに対
し、第７空気間隔ｇから第14空気間隔ｎまでの連
続する８個の空気間隔を密閉する場合には、全系
の結像面変動はこれら８個の空気間隔による結像
面変動の合計量3.91だけ同時に補正されるため、
いくぶん有利となる。
このように、空気間隔の一部を密閉する場合に
も第２図の鏡筒構造をそのまゝ使える。即ち、密
閉する空気間隔の両側のレンズを支持する支持筒
と外部鏡筒２０との間にＯ−リング等を挾み込め
ばよい。また第２図の圧力制御手段もそのまま使
える。即ち密閉された空気間隔と圧力制御装置２
３とを接続するとともに、圧力センサー２７を密
閉された空気間隔に配置する。こうすることによ
り、投影対物レンズの一部の空気間隔（空気室）
の圧力を最適圧力に保つことが可能となる。
以上のようにして、ステツパーを使用する場所
の環境に最も適した空気室圧力を維持することが
でき、大気圧の変動によつても倍率変動が少なく
結像面の変動も少ない状態で投影露光を行なうこ
とが可能となる。尚、投影対物レンズ内の空気室
に窒素ガスや炭酸ガス等の特定の気体を充満させ
て、その圧力を所定値に維持することによつても
同様に倍率変動を補正し得ることはいうまでもな
い。尚、空気室の圧力は標高に応じて決めてもよ
いし、その土地の平均大気圧（年間、月間等の）
であつてもよい。また、第２実施例において空気
室の密閉のみでは若干の倍率変動が残る場合があ
るが、これをも除去したい場合には、他の空気室
を密閉して該他の空気室の圧力を積極的に変化さ
せるよう制御（該他の空気室の屈折率を変える）
してもよい。また、ウエハ露光時に投影対物レン
ズを通過する露光々の一部吸収によつて該投影対
物レンズの光学特性が変化する場合にも、この他
の空気室の圧力を制御すれば光学特性の変化を補
正できる。
（発明の効果）
以上のごとく、本発明によれば投影対物レンズ
を光軸方向に動かすといつた機械的な動作を必要
とすることなく静的に倍率変動の補正が可能であ
り、光学性能を非対称に劣化させることもなく常
に安定した高精度の重ね合せマツチングがなさ
れ、超LSI等の高密度半導体素子の製造が大きく
寄与するものである。また、空気室が外部と少し
ではあるが通じていて長時間経過すると空気室の
圧力が無視し得ない程度に変化するような場合に
も、圧力制御手段の動作によつて常に最適圧力に
維持することができる。[Table] First Example: From Table 2 above, the magnification fluctuations in the first space a, that is, the space between the reticle and the projection objective lens, and the fifteenth space o, that is, the space between the wafer and the projection objective lens, both have positive values. and the total is 0.043. Therefore, by shielding all the spaces formed within the projection objective lens, that is, the second space b to the fourteenth space n, from atmospheric pressure and integrally sealing them, the spaces within the projection objective lens can be sealed. No resulting change in magnification occurs, and only the change in magnification occurs due to the first space a and the fifteenth space o, and it is possible to suppress the change in magnification to about 4% of the change in magnification that could occur in the entire system. Furthermore, by shielding the entire space formed within the projection objective lens from atmospheric pressure, the variation in the imaging plane is also reduced to 1.02 μm, which is suppressed to about 7% of the variation that can occur in the entire system. FIG. 2 is a diagram showing the lens barrel structure and pressure control means of the projection objective lens shown in Table 1. Fourteen lenses L 1 , L 2 , . . . , L 14 constituting the objective lens are supported by a first support tube 1, a second support tube 2, . . . , and a fourteenth support tube 14, respectively. By stacking these 14 support barrels, an internal lens barrel is substantially formed, which is integrally accommodated and supported by the outer lens barrel 20 and fixed by a retainer ring 21. First support tube 1 to 14th support tube 14 that support the first lens L1 to the fourteenth lens L14, respectively
Thirteen air chambers B to N are formed by
These air chambers B to N correspond to the air spacings b to n shown in FIG. 1, respectively. Here, through holes 2a to 13a are formed from the second support tube 2 that supports the second lens L2 to the thirteenth support tube 13 that supports the thirteenth lens, respectively, for communicating the adjacent air chambers. There is. Moreover, the 14th support tube 14 that supports the 14th lens L 14 located at the tip of the objective lens is
The fourteenth lens L14 is airtightly supported so as to isolate the thirteenth air chamber N from the outside air via the fourteenth lens L14 , and is also airtightly supported by the external lens barrel 20. The first support tube supporting the first lens L1 airtightly supports the first lens L1 . A gasket such as an O-ring is used for this airtight support. A tube 22 is inserted into the through hole 1a formed in the first support cylinder 1. A gasket is also provided between the first support tube 1 and the tube 22 for airtightness. A pressure control device 23 controls the pressure in the integral air chambers BN via the pipe 22. Pressure control device 23
When the pressure in the air chambers B to N is to be increased, pressurized air from the pressurized air supply device 24 is sent to the air chambers B to N through the pipe 22, and when the pressure in the air chambers B to N is to be lowered, it is sent to the air chamber B. The air in ~N is exhausted via the exhaust device 26. A filter 25 is arranged between the pressure control device 23 and the pressurized air supply device 24 to purify the air sent into the air chambers BN. The pressure sensor 27 is for detecting the pressure in the air chamber, for example, the pressure in the air chamber H. The pressure setting circuit 28 sets the atmospheric pressure depending on the altitude of the location where the projection exposure apparatus is used. Comparison circuit 29 compares the output signal of pressure sensor 27 and the output signal of pressure setting circuit 28, and generates a signal indicating the difference or magnitude relationship between the two output signals. The pressure control device 23 inputs the output signal of the comparison circuit 29, and
The pressures of the air chambers B to N are controlled so that the outputs of the pressure sensor 27 and the pressure setting circuit 28 have a predetermined relationship (match). In this way, the pressure in the air chambers B to N is always maintained at the atmospheric pressure depending on the altitude of the location where the exposure apparatus is used, so that the magnification of the projection objective lens can be precisely maintained. Second Example: FIG. 3 is a graph showing the values of each space for the amount of change in magnification ΔX shown in Table 2 above. The vertical axis of the graph in FIG. 3 is the magnification change amount ΔX, and the horizontal axis is the pressure change amount ΔP, and the symbols shown on each straight line in the figure correspond to each space. In addition, the amount of fold change ΔTx in the entire system is shown by a thick solid line. From the above Table 2 and the graph of FIG. 3, it can be seen that the magnification fluctuation amount caused by the third air gap C alone is the closest value to the magnification fluctuation amount S=1.004 due to the entire system. Therefore, by sealing only this third air gap C, it is possible to substantially correct the magnification fluctuation of the entire system. That is, the third air interval C
The amount of magnification variation due to 1.164 can be reduced to zero by sealing off this space from the atmosphere, so only the difference from the magnification variation due to the entire system becomes the actual amount of magnification variation. Therefore, in this case, the actual amount of change in magnification is −
0.16, which clearly decreases to 16%.
The magnification change ΔTx' of the entire system after this correction is shown by the dotted line in FIG. Now, it is possible to correct the magnification change due to atmospheric pressure fluctuations not only by one air gap but also by sealing a combination of a plurality of air gaps to isolate them from the atmosphere. For example, in the above objective lens, the seventh air interval g to the twelfth air interval l
If the six consecutive lens intervals up to 1 are sealed from the atmosphere and sealed integrally, the sum of the magnification fluctuations occurring in these six air intervals can be reduced to 0.935, so
It is possible to correct for a small variation of only 0.069 from the magnification variation of 1.004 that occurs in the entire system. In other words, the magnification variation in the entire system is corrected to 6.9%. In addition, if the 13th air interval m is also sealed off from the atmosphere in addition to these six air intervals, the amount of magnification variation in the entire system is -
The value becomes 0.067, which allows better correction. Furthermore, if the 14th air interval n is also sealed and sealed from the atmosphere to form a total of 8 sealed spaces, the amount of correction for magnification variation due to these 8 spaces will be 1.063, and the amount of magnification variation for the entire system will be It is possible to correct it as small as -0.059. Of these embodiments, a configuration in which only the third air gap C is sealed off from the atmosphere is the simplest, but by sealing this third air gap C, fluctuations due to the entire system of the imaging plane can be prevented. Become bigger. On the other hand, when eight consecutive air gaps from the 7th air gap g to the 14th air gap n are sealed, the image forming plane fluctuation of the entire system is the image forming plane change due to these eight air gaps. Since the total amount of 3.91 is corrected at the same time,
It's somewhat advantageous. In this way, the lens barrel structure shown in FIG. 2 can be used as is even when part of the air gap is sealed. That is, an O-ring or the like may be inserted between the external lens barrel 20 and the support tube that supports the lenses on both sides of the air gap to be sealed. Further, the pressure control means shown in FIG. 2 can be used as is. i.e. sealed air space and pressure control device 2
3 and the pressure sensor 27 is placed in a sealed air space. By doing this, the air spacing (air chamber) of a part of the projection objective
It becomes possible to maintain the pressure at the optimum pressure. As described above, it is possible to maintain the air chamber pressure most suitable for the environment where the stepper is used, and to perform projection exposure with less variation in magnification and less variation in the imaging plane even when atmospheric pressure changes. It becomes possible to do this. It goes without saying that magnification fluctuations can be similarly corrected by filling the air chamber in the projection objective lens with a specific gas such as nitrogen gas or carbon dioxide gas and maintaining the pressure at a predetermined value. Nor. The pressure in the air chamber may be determined depending on the altitude, or the average atmospheric pressure of the area (yearly, monthly, etc.)
It may be. In addition, in the second embodiment, a slight variation in magnification may remain if only the air chamber is sealed, but if you want to eliminate this as well, you can seal the other air chambers and actively increase the pressure in the other air chambers. (change the refractive index of the other air chamber)
You may. Furthermore, even if the optical characteristics of the projection objective lens change due to partial absorption of the exposed light that passes through the projection objective lens during wafer exposure, the change in optical characteristics can be prevented by controlling the pressure in the other air chamber. It can be corrected. (Effects of the Invention) As described above, according to the present invention, it is possible to statically correct magnification fluctuations without requiring mechanical operations such as moving the projection objective lens in the optical axis direction, and optical performance is improved. Stable and highly accurate overlay matching is always possible without causing asymmetrical deterioration of the components, which will greatly contribute to the production of high-density semiconductor devices such as VLSIs. In addition, even if the air chamber has a small communication with the outside and the pressure in the air chamber changes to a degree that cannot be ignored after a long period of time, the pressure control means will always maintain the optimum pressure. can do.
第１図は投影対物レンズのレンズ構成図、第２
図は本発明の第１実施例における投影対物レンズ
鏡筒の構造と圧力制御手段の説明図、第３図は本
発明の第２実施例を説明するためのグラフであ
る。
主要部分の符号の説明、Ｒ……投影原板（レチ
クル）、Ｗ……感光物体（ウエハ）、L1，L2〜L14
……レンズ、ａ，ｂ〜ｏ…空気間隔、Ｂ，Ｃ〜Ｎ
……空気室、２３……圧力制御装置、２７……圧
力センサー、２８……圧力設定回路、２９……比
較回路。
Figure 1 is a lens configuration diagram of the projection objective lens, Figure 2 is a lens configuration diagram of the projection objective lens.
The figure is an explanatory diagram of the structure of the projection objective lens barrel and the pressure control means in the first embodiment of the present invention, and FIG. 3 is a graph for explaining the second embodiment of the present invention. Explanation of symbols of main parts, R...Projection original plate (reticle), W...Photosensitive object (wafer), L1 , L2 to L14
...Lens, a, b~o...Air spacing, B, C~N
... Air chamber, 23 ... Pressure control device, 27 ... Pressure sensor, 28 ... Pressure setting circuit, 29 ... Comparison circuit.
Claims (1)
光する装置において、 前記投影原板と前記感光物体との間に配置され
て、前記パターンの像を前記感光物体上に結像す
る投影光学系であつて、 該投影光学系は、所定の空間だけ離して光軸方
向に並べた複数の光学素子と、該複数の光学素子
の夫々によつて挟まれた複数の空間の全部、もし
くは一部を外気から遮断して気密にする密封部材
とを有し、 さらに前記投影光学系の光学特性の変動を補正
するために、前記気密にされた空間内の圧力を、
前記投影光学系が設置される場所の大気圧に応じ
て決まる所定の圧力に制御する圧力制御手段を備
えたことを特徴とする投影光学装置。 ２ 前記圧力制御手段は、前記投影光学系内の決
密空間の圧力を検出する圧力センサーと、前記投
影光学系が設置される場所の標高等で決まる平均
大気圧に関する値を設定する設定回路と、前記圧
力センサーによつて検出される圧力と前記設定さ
れた値とを比較する回路とを含み、 前記気密空間の圧力が前記平均大気圧に応じて
決まる一定値に維持されるように制御することを
特徴とする特許請求の範囲第１項記載の装置。 ３ 前記気密空間内に密封する気体を空気以外の
特定気体にしたことを特徴とする特許請求の範囲
第１項、又は第２項記載の装置。[Scope of Claims] 1. An apparatus for projecting and exposing a pattern on a projection original plate onto a photosensitive object, the apparatus being disposed between the projection original plate and the photosensitive object, and forming an image of the pattern on the photosensitive object. A projection optical system that includes a plurality of optical elements arranged in the optical axis direction with a predetermined space apart, and a plurality of spaces sandwiched between each of the plurality of optical elements. or a sealing member that seals a part of the space from the outside air and makes it airtight, and furthermore, in order to compensate for fluctuations in the optical characteristics of the projection optical system, the pressure in the airtight space is adjusted to
A projection optical device characterized by comprising a pressure control means for controlling the pressure to a predetermined pressure determined according to the atmospheric pressure at a place where the projection optical system is installed. 2. The pressure control means includes a pressure sensor that detects the pressure in a dense space within the projection optical system, and a setting circuit that sets a value related to the average atmospheric pressure determined by the altitude of the location where the projection optical system is installed. , a circuit that compares the pressure detected by the pressure sensor with the set value, and controls the pressure in the airtight space to be maintained at a constant value determined according to the average atmospheric pressure. A device according to claim 1, characterized in that: 3. The device according to claim 1 or 2, wherein the gas sealed in the airtight space is a specific gas other than air.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5076384A JPS60195509A (en) | 1984-03-16 | 1984-03-16 | Projection optical device |
| DE19843443856 DE3443856A1 (en) | 1983-12-02 | 1984-11-30 | OPTICAL PROJECTION DEVICE |
| US07/291,324 US4883345A (en) | 1983-12-02 | 1988-12-28 | Projection optical apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5076384A JPS60195509A (en) | 1984-03-16 | 1984-03-16 | Projection optical device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60195509A JPS60195509A (en) | 1985-10-04 |
| JPH0570124B2 true JPH0570124B2 (en) | 1993-10-04 |
Family
ID=12867868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5076384A Granted JPS60195509A (en) | 1983-12-02 | 1984-03-16 | Projection optical device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60195509A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2503451B2 (en) * | 1985-12-26 | 1996-06-05 | 株式会社ニコン | Projection exposure method and apparatus |
| JP3041939B2 (en) * | 1990-10-22 | 2000-05-15 | 株式会社ニコン | Projection lens system |
| TWI402599B (en) * | 2008-06-20 | 2013-07-21 | Hon Hai Prec Ind Co Ltd | Lens module and camera module |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5699308A (en) * | 1979-12-29 | 1981-08-10 | Zeiss Jena Veb Carl | High performance objective lens |
-
1984
- 1984-03-16 JP JP5076384A patent/JPS60195509A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5699308A (en) * | 1979-12-29 | 1981-08-10 | Zeiss Jena Veb Carl | High performance objective lens |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60195509A (en) | 1985-10-04 |
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