JP2874284B2 - Interval measuring device - Google Patents
Interval measuring deviceInfo
- Publication number
- JP2874284B2 JP2874284B2 JP2136827A JP13682790A JP2874284B2 JP 2874284 B2 JP2874284 B2 JP 2874284B2 JP 2136827 A JP2136827 A JP 2136827A JP 13682790 A JP13682790 A JP 13682790A JP 2874284 B2 JP2874284 B2 JP 2874284B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- conversion element
- wafer
- mask
- interval
- 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
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7073—Alignment marks and their environment
- G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices 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2つの物体間の間隔を高精度に測定する間隔
測定装置に関し、例えば半導体製造装置において、マス
クとウエハとの間隔を測定し、所定の値に制御するとき
に好適なものである。Description: TECHNICAL FIELD The present invention relates to an interval measuring apparatus for measuring an interval between two objects with high accuracy, for example, in a semiconductor manufacturing apparatus, measuring an interval between a mask and a wafer, This is suitable for controlling to a predetermined value.
(従来の技術) 従来より半導体製造装置においては、マスクとウエハ
との間隔を間隔測定装置等で測定し、所定の間隔となる
ように制御した後、マスク面上のパターンをウエハ面上
に露光転写している。これにより高精度な露光転写を行
っている。2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, the distance between a mask and a wafer is measured by an interval measuring device or the like, and controlled so as to be a predetermined distance, and then the pattern on the mask surface is exposed on the wafer surface. Transcribed. As a result, highly accurate exposure transfer is performed.
第8図は特開昭61−111402号公報で提案されている間
隔測定装置の概略図である。同図においては第1物体と
してのマスクMと第2物体としてのウエハWとを対向配
置し、レンズL1によって光束をマスクMとウエハWとの
間の点PSに集光させている。FIG. 8 is a schematic view of an interval measuring device proposed in Japanese Patent Application Laid-Open No. 61-111402. And is focused on a point P S between the mask M and the wafer W and arranged opposite, the mask M and the wafer W to the light beam by the lens L1 of the second object as the first object in the drawing.
このとき光束はマスクM面上をウエハW面上で各々反
射し、レンズL2を介してスクリーン(センサー)S面上
の点PW,PMに集束投影されている。マスクMとウエハW
との間隔はスクリーンS面上の光束の集光点PW,PMとの
間隔を検出することにより測定している。Light beam at this time is respectively reflected the mask M Menjo on the wafer W surface, a screen through a lens L2 (sensor) point on the S-plane P W, and is focused projected to P M. Mask M and wafer W
Interval converging point P W of the light beam on the screen S surface with, is measured by detecting the distance between the P M.
(発明が解決しようとする問題点) しかしながら、第8図に示す装置はウエハWに傾き誤
差があると光束のスクリーン(センサー)S面への入射
位置に誤差が生じマスクMとウエハWとの間隔検出精度
が低下してくるという問題点があった。本発明はマスク
とウエハに相当する第1物体と第2物体とを対向配置し
て両者の間隔を測定する際、例えば第1物体と第2物体
の間隔を精度良く検出できる間隔測定装置の提供を目的
とする。(Problems to be Solved by the Invention) However, in the apparatus shown in FIG. 8, if there is a tilt error in the wafer W, an error occurs in the incident position of the light beam on the screen (sensor) S surface, and the mask M and the wafer W There is a problem that the interval detection accuracy is reduced. The present invention provides an interval measuring apparatus capable of accurately detecting, for example, an interval between a first object and a second object when a first object and a second object corresponding to a mask and a wafer are arranged to face each other and an interval between the first object and the second object is measured. With the goal.
(問題点を解決するための手段) 本発明の間隔測定装置は、波面変換素子を設けた第1
物体と第2物体とを対向配置し、該第1物体上の波面変
換素子に光源手段から複数の波長の光束を同時又は順次
照射し、該波面変換素子によって所定方向に偏向した光
を該第2物体面で反射させた後、受光手段面上に導光
し、該受光手段面上における少なくとも2つの波長の光
の入射位置を個別に検出することにより、該第1物体と
第2物体との間隔を求めたことを特徴としている。(Means for Solving the Problems) The distance measuring apparatus according to the present invention has a first wavefront converting element.
An object and a second object are arranged to face each other, and light beams of a plurality of wavelengths are simultaneously or sequentially irradiated from the light source means to the wavefront conversion element on the first object, and the light deflected in a predetermined direction by the wavefront conversion element is emitted to the second object. After the light is reflected by the two object surfaces, the light is guided onto the light receiving means surface, and the incident positions of at least two wavelengths of light on the light receiving means surface are individually detected, whereby the first object and the second object are The feature is that the interval of is determined.
この他本発明では、一部に第1波面変換素子と第2波
面変換素子とを設けた第1物体と第2物体とを対向配置
し、該第1物体面上の第1波面変換素子に光源手段から
複数の波長の光束を同時又は順次照射し、該第1波面変
換素子からの所定次数の回折光を該第2物体面で反射さ
せた後、該第1物体面上の第2波面変換素子に入射さ
せ、該第2波面変換素子からの所定次数の回折光を受光
手段面上に導光し、該受光手段面上における少なくとも
2つの波長の回折光の入射位置を個別に検出することに
より、該第1物体と第2物体との間隔を求めたことを特
徴としている。又、本発明の露光装置は前述の間隔測定
装置を用いて、第1物体と第2物体との間隔を所定値に
して該第1物体面上のパターンを第2物体面上に露光転
写していることを特徴としている。In addition, in the present invention, the first object and the second object, which are partially provided with the first wavefront conversion element and the second wavefront conversion element, are arranged to face each other, and the first wavefront conversion element on the first object plane is provided. After irradiating light beams of a plurality of wavelengths simultaneously or sequentially from the light source means and reflecting the diffracted light of a predetermined order from the first wavefront conversion element on the second object surface, the second wavefront on the first object surface The light is incident on the conversion element, and diffracted light of a predetermined order from the second wavefront conversion element is guided on the light receiving means surface, and the incident positions of the diffracted lights of at least two wavelengths on the light receiving means surface are individually detected. Thus, the distance between the first object and the second object is obtained. Further, the exposure apparatus of the present invention uses the above-described distance measuring apparatus to set the distance between the first object and the second object to a predetermined value, and to transfer the pattern on the first object surface onto the second object surface by exposure. It is characterized by having.
(実施例) 第1図は本発明を半導体製造装置のマスクとウエハと
の間隔を測定する装置に適用した場合の一実施例の光学
系の概略図である。第2図は第1図の第1物体と第2物
体近傍の拡大模式図である。第1,第2図において1は例
えばHe−Neレーザーや半導体レーザー等の光源からの光
束、2は板状の第1物体で例えばマスク、3は板状の第
2物体で例えばウエハであり、マスク2とウエハ3は第
2図に示すように間隔dOを隔てて対向配置されている。
4,5は各々マスク2面上の一部に設けた第1,第2波面変
換素子である。波面変換素子としては例えば回折格子、
グレーティングレンズ、フレネルゾーンプレート等の物
理光学素子が適用可能である。以上、波面変換素子を物
理光学素子と称することにする。7は集光レンズであ
り、その焦点距離はfSである。(Embodiment) FIG. 1 is a schematic diagram of an optical system according to an embodiment in which the present invention is applied to an apparatus for measuring a distance between a mask and a wafer in a semiconductor manufacturing apparatus. FIG. 2 is an enlarged schematic view of the vicinity of the first object and the second object in FIG. First, the light beam from the light source 1 such as for example H e -N e laser or a semiconductor laser in FIG. 2, 2 a plate-shaped first object, for example a mask, 3 in a plate-like second object, for example a wafer The mask 2 and the wafer 3 are opposed to each other with an interval d O as shown in FIG.
Reference numerals 4 and 5 denote first and second wavefront conversion elements respectively provided on a part of the mask 2 surface. As a wavefront conversion element, for example, a diffraction grating,
Physical optical elements such as a grating lens and a Fresnel zone plate can be applied. As described above, the wavefront conversion element will be referred to as a physical optical element. 7 is a condensing lens, its focal length is f S.
8は受光手段で集光レンズ7の焦点位置に配置されて
おり、ラインセンサーやPSD等から成り、入射光束の重
心位置を検出している。9は信号処理回路であり、受光
手段8からの信号を用いて受光手段8面上に入射した光
束の重心位置を求め、後述するようにマスク2とウエハ
3との間隔dOを演算し求めている。Numeral 8 denotes a light receiving means, which is arranged at the focal position of the condenser lens 7 and comprises a line sensor, a PSD or the like, and detects the position of the center of gravity of the incident light beam. Reference numeral 9 denotes a signal processing circuit which calculates the center of gravity of the light beam incident on the surface of the light receiving means 8 by using the signal from the light receiving means 8 and calculates and calculates the distance d O between the mask 2 and the wafer 3 as described later. ing.
10は光プローブであり、集光レンズ7や受光手段8、
そして必要に応じて信号処理回路9を有しており、マス
ク2やウエハ3とは相対的に移動可能となっている。10
1は波長モニターであり、光源LDからの発振波長を検出
している。Reference numeral 10 denotes an optical probe, which includes a condenser lens 7, a light receiving unit 8,
A signal processing circuit 9 is provided as necessary, and is relatively movable with respect to the mask 2 and the wafer 3. Ten
Reference numeral 1 denotes a wavelength monitor which detects an oscillation wavelength from the light source LD.
本実施例においては半導体レーザーLDを光源として用
い、その注入電流を注入電流制御手段17で制御すること
により、波長モニター101で発振波長を監視しつつ、発
振波長の異なる複数の波長の光束を同時又は順次放射し
ている。光源LDと注入電流制御手段17は光源手段102の
一要素を構成している。In the present embodiment, the semiconductor laser LD is used as a light source, and the injection current is controlled by the injection current control means 17 so that the wavelength monitor 101 monitors the oscillation wavelength and simultaneously emits a plurality of light beams having different oscillation wavelengths. Or radiate sequentially. The light source LD and the injection current control means 17 constitute one element of the light source means 102.
光源LDからの光束1(中心波長λ=830nm)をマスク
2面上の第1フレネルゾーンプレート(以下FZPと略記
する)4面上の点Aに紙面と平行な平面内で垂直に入射
させている。そして第1のFZP4からの角度θ1で回折す
る所定次数の回折光をウエハ3面上の点B(C)(ウエ
ハ3とマスク2との間隔がdOのときは点Bで、(dO+
dG)のときは点Cで反射)で反射させている。このうち
反射光31はウエハ3がマスク2に近い位置P1(間隔dO)
に位置しているときの反射光、反射光32はウエハ3が位
置P1から距離dGだけ変位したときの反射光である。A light beam 1 (center wavelength λ = 830 nm) from a light source LD is perpendicularly incident on a point A on a first Fresnel zone plate (hereinafter abbreviated as FZP) 4 on a mask 2 in a plane parallel to the paper. I have. Then, the diffracted light of a predetermined order diffracted at an angle θ1 from the first FZP4 is converted to a point B (C) on the surface of the wafer 3 (point B when the distance between the wafer 3 and the mask 2 is d O , and (d O +
When the d G) which is reflected by reflection) at point C. The reflected light 31 is at a position P1 (interval d O ) where the wafer 3 is close to the mask 2
Reflected light when located, the reflected light 32 is reflected light when the wafer 3 is displaced from the position P1 by a distance d G.
次いでウエハ3からの反射光を第1物体2面上の第2
のFZP5面上の点D(E)に入射させている。尚、第2の
FZP5は入射光束の入射位置に応じて出射回折光の射出角
を変化させる光学作用を有している。Next, the reflected light from the wafer 3 is converted to the second light on the first object 2 surface.
At the point D (E) on the FZP5 plane. In addition, the second
The FZP 5 has an optical function of changing the exit angle of the output diffracted light according to the incident position of the incident light beam.
そして第2のFZP5から角度θ2で回折した所定次数の
回折光(61,62)を集光レンズ7を介して受光手段8面
上に導光している。Then, the diffracted light (61, 62) of a predetermined order diffracted at an angle θ2 from the second FZP 5 is guided through the condenser lens 7 onto the light receiving means 8 surface.
そして、このときの受光手段8面上における入射光束
(61,62)の重心位置を用いてマスク2とウエハ3との
間隔を演算し求めている。Then, the distance between the mask 2 and the wafer 3 is calculated using the position of the center of gravity of the incident light beam (61, 62) on the surface of the light receiving means 8 at this time.
本実施例ではマスク2面上に設けた第1,第2のFZP4,5
は予め設定された既知のピッチで構成されており、それ
らに入射した光束の所定次数(例えば±1次)の回折光
の回折角度θ1,θ2は中心波長λに対応して予め求めら
れている。In this embodiment, the first and second FZPs 4, 5 provided on the mask 2 surface are provided.
Are configured with a known pitch set in advance, and the diffraction angles θ 1 and θ 2 of the diffracted light of a predetermined order (for example, ± 1 order) of the light flux incident thereon are obtained in advance corresponding to the center wavelength λ. ing.
第3図はマスク2面上の第1,第2のFZP4,5の機能及び
マスク2とウエハ3との間隔との関係を示す説明図であ
る。FIG. 3 is an explanatory view showing the functions of the first and second FZPs 4 and 5 on the surface of the mask 2 and the relationship between the distance between the mask 2 and the wafer 3.
同図(A)は第1,第2FZP4,5の上面図、同図(B)は
第1,第2FZP4,5を通過する光束のB方向から見た図、同
図(C)は同じくA方向から見た図である。FIG. 2A is a top view of the first and second FZPs 4 and 5, FIG. 2B is a view of the light beam passing through the first and second FZPs 4 and 5 from the B direction, and FIG. It is the figure seen from the direction.
本実施例においては、第1のFZP4に入射光を折り曲げ
る作用をしているが、この他収束、又は発散作用を持た
せるようにしても良い。In the present embodiment, the first FZP 4 has a function of bending incident light, but may have a convergence or divergence function.
同図(A),(B),(C)に示すように第2のFZP5
は場所によって回折方向が少しずつ変えられる構成にな
っており、例えば点11はマスク2とウエハ3との間隔が
100μmのときの出射光束の重心透過点でマスク2とウ
エハ3との間隔が増すにつれて出射光束の透過点は同図
(A)において右方に移動し、間隔が200μmになった
ときは点12を透過するように設定している。As shown in FIGS. 7A, 7B and 7C, the second FZP5
Has a configuration in which the diffraction direction can be changed little by little depending on the location. For example, at point 11, the distance between the mask 2 and the wafer 3 is
As the distance between the mask 2 and the wafer 3 increases at the transmission point of the center of gravity of the emitted light beam at 100 μm, the transmission point of the emitted light beam moves rightward in FIG. Is set to pass through.
FZPのパターンは同図(A)においてA方向には収
束、発散のパワーを持たせていないが光束の拡がりを調
整する為に持たせても良い。The FZP pattern does not have the power of convergence and divergence in the direction A in FIG. 3A, but may have it in order to adjust the spread of the light beam.
本実施例ではB方向に対しては第1図に示すように出
射角度5°方向に距離fM=1000μmの位置に集光するよ
うに収束のパワーを持たせている。In this embodiment, as shown in FIG. 1, the power of convergence is provided in the direction B at a distance f M = 1000 μm in the direction of the output angle of 5 ° in the direction B.
尚、第3図においてマスク2とウエハ3との間隔測定
範囲を例えば100μm〜200μmとした場合には、これに
対応させて第1,第2のFZP4,5の領域を設定すれば良い。When the distance measurement range between the mask 2 and the wafer 3 is set to, for example, 100 μm to 200 μm in FIG. 3, the first and second FZPs 4 and 5 may be set correspondingly.
次に第1図を用いてマスク2とウエハ3との間隔を求
める方法について説明する。Next, a method for determining the distance between the mask 2 and the wafer 3 will be described with reference to FIG.
第1図に示すように回折光61と回折光62との交点Fか
らマスク2までの距離をfMとすると AD=2dOtan θ1, AE=2(dO+dG)tanθ1, ∴dM=DE=AE−AD=2dGtanθ1 ……(1) dM=2・fM・tanθ2 ……(2) である。受光手段8面上における入射光の動き量Sは S=2・fS・tanθ2 ……(3) 従って(1),(2),(3)式より となる。As shown in FIG. 1 , assuming that the distance from the intersection F between the diffracted light 61 and the diffracted light 62 to the mask 2 is f M , AD = 2d O tan θ 1 , AE = 2 (d O + d G ) tan θ 1 , ∴ d M = DE = AE−AD = 2d G tan θ 1 (1) d M = 2 · f M tan θ 2 (2) The movement amount S of the incident light on the surface of the light receiving means 8 is S = 2 · f S · tan θ 2 (3) Therefore, from the equations (1), (2) and (3), Becomes
本実施例ではマスクMとウエハWとの間隔(ギャッ
プ)検出用の光束として光源手段102より波長の異なる
複数の光束、例えばλ1,λ2(λ1≠λ2)の2つの光束
を同時に又は順次放射している。In this embodiment, a plurality of light beams having different wavelengths, for example, two light beams of λ 1 and λ 2 (λ 1 ≠ λ 2 ) are simultaneously emitted from the light source means 102 as light beams for detecting the gap (gap) between the mask M and the wafer W. Or radiate sequentially.
これによりマスクM面上の第2のFZP5に対して実効的
な焦点距離fMが異なる2つの状態を作り出している。そ
して各々の波長λ1,λ2に対応する受光手段8面上への
間隔信号光束の入射位置S1,S2を検出し、それらの入射
位置の差S(S=S1−S2)からマスクMとウエハWとの
間隔を検出している。Thus, two states in which the effective focal length f M is different from the second FZP 5 on the mask M surface are created. Then, the incident positions S 1 and S 2 of the interval signal light beam on the light receiving means 8 corresponding to the wavelengths λ 1 and λ 2 are detected, and the difference S (S = S 1 −S 2 ) between the incident positions is detected. , The distance between the mask M and the wafer W is detected.
ここで波長λにおけるマスクM面上の第2のFZP5の焦
点距離をf、マスクMとウエハWとの間隔をdO、ウエハ
Wから交点Fまでの距離をaとすると a=f+dO となる。従って波長λにおける光束重心ずれ量の間隔変
動量dGに対する倍率Aは である。Here, assuming that the focal length of the second FZP5 on the mask M surface at the wavelength λ is f, the distance between the mask M and the wafer W is d O , and the distance from the wafer W to the intersection F is a, a = f + d O. . Therefore, the magnification A with respect to the interval variation d G of the luminous flux center-of-gravity deviation at the wavelength λ is It is.
次に光源の波長をλ、グレーティングレンズの輪帯の
半径をrm(mは輪帯番号)とすると、焦点距離fとのあ
いだに、 の関係が成り立ち、これよりfは となる。Next, assuming that the wavelength of the light source is λ and the radius of the annular zone of the grating lens is r m (m is the annular zone number), the focal length f is Holds, from which f is Becomes
アライメント光束の波長がΔλ変化したとすると焦点
距離f′は となる。If the wavelength of the alignment light beam changes by Δλ, the focal length f ′ becomes Becomes
即ち波長λ1に対応する第2のFZP5の焦点距離をfM1と
し、同様に波長λ2に対応する第2のFZP5の焦点距離をf
M2とすると (但しfM1≠fM2) となる。That is, the focal length of the second FZP5 corresponding to the wavelength λ 1 is f M1, and the focal length of the second FZP 5 corresponding to the wavelength λ 2 is f
M2 (However, f M1 ≠ f M2 ).
但し、厳密には (fS1,fS2は波長λ1,λ2に対応する集光レンズ7の実
効焦点距離) となる。However, strictly speaking (F S1 and f S2 are the effective focal lengths of the condenser lens 7 corresponding to the wavelengths λ 1 and λ 2 ).
即ち2つの波長λ1とλ2との波長差が大きいとき、例
えばS≧2.0a以上あるときは同時に又波長差が小さく、
例えばS<2.0a以下のときは順次放射するようにしてい
る。ここにaは各波長でのセンサー上スポット径のいず
れか大きい方を示す。That is, when the wavelength difference between the two wavelengths λ 1 and λ 2 is large, for example, when S ≧ 2.0a or more, the wavelength difference is also small at the same time,
For example, when S <2.0a or less, emission is performed sequentially. Here, a indicates the larger of the spot diameter on the sensor at each wavelength.
本実施例では半導体レーザを注入電流制御手段17によ
り波長モニター101で監視しつつ発振波長を10%変調し
て用いた。即ちλ2=1.1λ1(λ1=0.830μm)。In this embodiment, the semiconductor laser is monitored by the injection current control means 17 with the wavelength monitor 101 and the oscillation wavelength is modulated by 10%. That is, λ 2 = 1.1λ 1 (λ 1 = 0.830 μm).
ここでfM1=214.723(μm)とするとfM2=195.124
(μm)となる。If f M1 = 214.723 (μm), f M2 = 195.124
(Μm).
又、第3図(A)に示す入射側の第1のFZP4のA方向
の格子ピッチPAをtanθ1(λ1)=0.577(θ1(λ1)=
30°)となるようにするとPA=1.66μm、このときtan
θ1(λ2)=0.659(θ1(λ2)=33.37°)、fs1≒fS2
=30.0(mm)とすると波長λ1,λ2の光束を間隔(ギャ
ップ)検出用のマークに照射したときの受光手段8面上
で光束の入射位置の変化Sは S=20.704dG となり、マスク2とウエハ3との間隔1μm当たりの変
化に対して、受光手段8面上の光束は15μm移動するこ
とになる。受光手段8として位置分解能が0.3μmのPSD
を用いると、原理的に0.02μmの分解能でマスク2とウ
エハ3の間隔を測定することが可能となる。The third view tanθ the grating pitch P A of the first FZP4 the A direction of the incident side as shown in (A) 1 (λ 1) = 0.577 (θ 1 (λ 1) =
30 °), P A = 1.66 μm, then tan
θ 1 (λ 2 ) = 0.659 (θ 1 (λ 2 ) = 33.37 °), f s1 ≒ f S2
= 30.0 wavelength lambda 1 (mm), the change S of the incident position of the light beam on the light receiving means 8 surface when irradiated with light flux of lambda 2 to the mark interval (gap) for detecting the S = 20.704D G becomes, The light beam on the surface of the light receiving means 8 moves by 15 μm with respect to a change per 1 μm interval between the mask 2 and the wafer 3. PSD with a position resolution of 0.3 μm as the light receiving means 8
In principle, the distance between the mask 2 and the wafer 3 can be measured with a resolution of 0.02 μm.
従ってマスク2とウエハ3とがy方向にギャップ変動
のない状態、即ちdG=0の時に、波長が変化しても受光
手段8面上での光束の重心位置が変動しない(即ちS=
0となる)ようにマスク及びウエハのグレーティングレ
ンズを設計しておけば、入射位置の差Sはマスクとウエ
ハとのギャップ量に比例することになる。よって予め
λ,Δλ,マスクとウエハの間隔dOの値を設定し、FSP5
の焦点距離f,入射位置の差Sの値を求めて差分Sの値を
算出しておくことにより、Sの値を受光手段8の検出結
果より求め(a)又は(b)式に代入して簡単にマス
ク、ウエハ間隔の変動量dGを検出できる。又、この時波
長はΔλだけ変動させた時の光束重心位置移動方向はマ
スク、ウエハのギャップ変動方向、即ちSの正負に対応
しており、予めこの対応関係を求めておけば、波長変動
時の光束重心位置移動方向からギャップ変動方向も検出
することができる。Accordingly, when the gap between the mask 2 and the wafer 3 does not change in the y direction, that is, when d G = 0, the center of gravity of the light beam on the light receiving means 8 surface does not change even if the wavelength changes (ie, S =
If the grating lens of the mask and the wafer is designed to be 0), the difference S between the incident positions is proportional to the gap amount between the mask and the wafer. Therefore, the values of λ, Δλ, the distance d O between the mask and the wafer are set in advance, and FSP5
By calculating the value of the difference S by calculating the value of the difference S between the focal length f and the incident position, the value of S is obtained from the detection result of the light receiving means 8 and substituted into the equation (a) or (b). simple mask, can detect variation d G of wafer interval Te. At this time, when the wavelength is changed by Δλ, the direction of movement of the center of gravity of the light beam corresponds to the direction of change in the gap between the mask and the wafer, that is, the sign of S. The gap variation direction can also be detected from the light flux barycenter position movement direction.
ここで変動量dG=0の時の入射光束の差分Sは必ずし
も0でなくてもよく、dG=0の時のSの絶対値及び波長
変動時の光束重心位置移動方向を予め求めておけば、間
隔検出時の差分Sの値とdG=0の時のSの値の差分を
(a)又は(b)式に代入してマスク、ウエハ間のギャ
ップ量dOを求めることができる。ギャップ設定は第1の
方法としてはマスク、ウエハ間のギャップ量dGに対する
前述波長変更時の光束重心位置移動量Sの関係式、即ち
(a)又は(b)式を予め求めておき、ギャップ検出時
に光源から所定の2波長の光束を順次出射させてそれぞ
れの波長における光束重心位置を受光手段8で検出して
光束重心位置移動量Sを求め、このSの値から(a)又
は(b)式を用いて双方の物体間のギャップ量dGを求
め、そのときのギャップ量dGに相当する量だけ第1物体
若しくは第2物体をZ方向に移動させる。Here, the difference S of the incident light beam when the variation d G = 0 may not always be 0, and the absolute value of S when d G = 0 and the direction of movement of the center of gravity of the light beam when the wavelength varies are obtained in advance. In other words, it is possible to determine the gap amount d O between the mask and the wafer by substituting the difference between the value of the difference S when detecting the interval and the value of S when d G = 0 into the equation (a) or (b). it can. Gap setting obtained beforehand relationship of the light beam centroid position movement amount S of the time change aforementioned wavelength with respect to the gap amount d G between the first mask as a method, a wafer, i.e., the (a) or (b) wherein the gap At the time of detection, light beams of predetermined two wavelengths are sequentially emitted from the light source, and the light beam centroid position at each wavelength is detected by the light receiving means 8 to obtain the light beam centroid position shift amount S. From the value of S, (a) or (b) ) determine the gap size d G between both the object using the equation, to move the quantity by the first object or the second object corresponding to the gap amount d G at that time in the Z direction.
第2の方法としてはギャップ検出時に光源から所定の
2波長の光束を順次出射させて受光手段8で得られた光
束重心位置からSとギャップ量dGを打ち消す方向を検出
し、その方向にSに見合った所定量だけ第1物体若しく
は第2物体をZ方向に移動させ、移動が終わればその時
点で再び所定の2波長の光束を順次出射させてdGが許容
範囲になるまで上述の検出、移動を繰り返して行う。以
上のCPUの位置合わせ手順を、それぞれ第5図(1),
(2)に示す。A second method detects the direction of canceling the S and the gap amount d G from the light centroid position obtained by the light receiving means 8 sequentially emitting light beams of two wavelengths from the light source of a predetermined upon detection gap, S in that direction The first object or the second object is moved in the Z direction by a predetermined amount corresponding to the above, and when the movement is completed, the light beams of the predetermined two wavelengths are sequentially emitted again at that time, and the above-described detection is performed until d G is within the allowable range. And the movement is repeated. FIG. 5 (1) and FIG.
This is shown in (2).
上述実施例のようにすることで検出面上にアライメン
ト光束の重心位置検出のための基準点、即ちdG=0のと
きの受光面上の光束重心位置を求めておく必要がなく、
光源の波長を変調又は選択的にシフトすることにより、
被測定物体間の相対ギャップ量を簡単に検出することが
できる。By using the above-described embodiment, it is not necessary to determine the reference point for detecting the center of gravity of the alignment light beam on the detection surface, that is, the position of the center of the light beam on the light receiving surface when d G = 0.
By modulating or selectively shifting the wavelength of the light source,
The relative gap amount between the measured objects can be easily detected.
又、ウエハ2か傾いた場合、この傾きによる検出面上
での光束重心位置移動量分は光源の波長を変化させても
変化しないのでSに変化はない。これは光束照射手段や
検出手段に位置の変化があっても同様でる。従ってSを
検出することによりウエハの傾き、光束照射手段や検出
器の位置変化の影響を受けない検出ができる。When the wafer 2 is tilted, S does not change because the amount of movement of the center of gravity of the light beam on the detection surface due to the tilt does not change even if the wavelength of the light source is changed. This is the same even if the position of the light beam irradiation means or the detection means changes. Therefore, by detecting S, it is possible to perform detection without being affected by the inclination of the wafer, the change in the position of the light beam irradiation means or the position of the detector.
図9はこのときウエハ3が傾いたときの間隔測定にお
ける光路の説明図である。同図において、マスク2とウ
エハ3が互いに平行のときに、ウエハ3が傾いて点線の
如くウエハ3′となったときのスポット(光束)の受光
手段8面上への入射位置は次のようになる。FIG. 9 is an explanatory diagram of an optical path in the interval measurement when the wafer 3 is tilted at this time. In the same figure, when the mask 2 and the wafer 3 are parallel to each other, the incident position of the spot (light beam) on the surface of the light receiving means 8 when the wafer 3 is inclined and becomes the wafer 3 'as shown by a dotted line is as follows. become.
ウエハ3の傾きによるスポットの移動量は波長によらず
一定であるから ΔP1=ΔP2 となる。従って P1′−P1=P2′−P2 P2−P1=P2′−P1′ となり、ウハエ3が傾いたときでも受光手段8面上のス
ポットの間隔(P2′−P1′)は傾かないときのスポット
の間隔(P2−P1)と同じになる。 Since the movement amount of the spot due to the inclination of the wafer 3 is constant regardless of the wavelength, ΔP1 = ΔP2. Therefore, P1'-P1 = P2'-P2 P2-P1 = P2'-P1 ', and even when the fly 3 is tilted, the spot interval (P2'-P1') on the surface of the light receiving means 8 is not tilted. (P2-P1).
本実施例では光源として半導体レーザを用い、注入電
流を制御することにより、発振波長を変調した。この結
果、1つの光束の重心位置の変動を検出するだけで、相
対間隔変動量の絶対値を検出することができ、波長の異
なる2光束を別光源から発生させる場合の2光束間の相
対位置ずれ等を問題にせずにすむ。In this example, a semiconductor laser was used as a light source, and the injection current was controlled to modulate the oscillation wavelength. As a result, it is possible to detect the absolute value of the amount of change in the relative spacing only by detecting the change in the center of gravity of one light beam, and to determine the relative position between two light beams when two light beams having different wavelengths are generated from different light sources. It is not necessary to make the shift or the like a problem.
本実施例ではウエハ3の1つの位置に対する第2のFZ
P5からの回折光は光軸63に対して特定の角度をもって集
光レンズ7に入射し、受光手段8が集光レンズ7の焦点
位置に設置されているので光ブローブ10を光軸63上の、
どの位置に設置しても、又光軸と垂直方向に多少ズレて
いても受光手段8への入射光位置は不変である。これに
より光ブローブの変動に伴う測定誤差を軽減させてい
る。In this embodiment, the second FZ for one position of the wafer 3
The diffracted light from P5 enters the condenser lens 7 at a specific angle with respect to the optical axis 63. Since the light receiving means 8 is located at the focal position of the condenser lens 7, the optical probe 10 ,
Regardless of the position, the position of the light incident on the light receiving means 8 remains unchanged even if it is slightly displaced in the direction perpendicular to the optical axis. This reduces the measurement error due to the fluctuation of the optical probe.
但し、光ブローブ10の位置誤差がある程度許容されて
いる場合には、受光手段8は集光レンズ7の焦点位置に
厳密に設置される必要はない。However, when the position error of the optical probe 10 is allowed to some extent, the light receiving means 8 does not need to be strictly installed at the focal position of the condenser lens 7.
尚、第1図の実施例において集光レンズ7を用いずに
第4図(A),(B)に示すように構成しても第1図の
実施例に比べて受光手段8に入射する光束が多少大きく
なるが本発明の目的を略達成することができる。Note that, even if the configuration shown in FIGS. 4A and 4B is used without using the condenser lens 7 in the embodiment of FIG. 1, the light is incident on the light receiving means 8 as compared with the embodiment of FIG. Although the luminous flux is somewhat large, the object of the present invention can be substantially achieved.
第4図(A)は第1図の実施例において集光レンズ7
を省略したときの実施例の概略図である。FIG. 4 (A) shows a condenser lens 7 in the embodiment of FIG.
It is the schematic of an Example when it abbreviates.
第4図(B)は第4図(A)の実施例におけるマスク
2面上のFZP(物理光学素子)5を入射光束に対して一
定方向に出射させる光学作用を有し、集光作用を有さな
いような作用をもつものに置き換えた実施例を示してい
る。具体的にはFZP(物理光学素子)5、そして平行等
間隔な線状格子よりなる回折格子等が用いられる。この
場合も第4図(A)の実施例と同様、本発明の目的を略
達成することができる。FIG. 4B has an optical function of causing the FZP (physical optical element) 5 on the surface of the mask 2 in the embodiment of FIG. An embodiment is shown in which the device is replaced with one having an action not having. Specifically, an FZP (physical optical element) 5 and a diffraction grating composed of linear gratings at equal intervals are used. In this case as well, the object of the present invention can be substantially achieved as in the embodiment of FIG. 4 (A).
尚、第4図(B)に示す実施例においてFZP(回折格
子)5を省略し、ウエハ3から反射した光束がマスク2
を透過するようにし、この透過光を受光する位置に受光
手段を配置するようにしても良い。The FZP (diffraction grating) 5 is omitted in the embodiment shown in FIG.
May be transmitted, and a light receiving unit may be arranged at a position where the transmitted light is received.
又、第4図(A),(B)の入射側のFZP(回折格
子)4を省略し、光源LDからの入射光束がマスク2に入
射する前からマスク面法線に対して傾斜しているように
構成しても良い。Also, the incident side FZP (diffraction grating) 4 in FIGS. 4A and 4B is omitted, and the incident light beam from the light source LD is inclined with respect to the mask surface normal before entering the mask 2. May be configured.
更に第4図(A),(B)においてウエハ3上に回折
格子を形成し、FZP(回折格子)4からの回折光を該FZP
(回折格子)で回折させてFZP(回折格子)5の方向に
導光するように構成しても良い。4 (A) and 4 (B), a diffraction grating is formed on the wafer 3, and the diffracted light from the FZP (diffraction grating) 4 is
(Diffraction grating) and the light may be guided in the direction of FZP (diffraction grating) 5.
本発明による第2の実施例を適用した半導体露光装置
の要部斜視図を第6図に示す。第1図と同一部材は同一
符号で示してある。主な構成要素は第1実施例と同じで
あるが、本実施例ではアライメントヘッド内に光源とし
て発振中心波長の異なる2つの半導体レーザ10−1,10−
2を設けた。半導体レーザ10−1,10−2からの光束はハ
ーフミラー12aにより出射した時に主光線が重なるよう
に光路調整されている。600はステージでステージドラ
イバー601でX,Y,Z方向に駆動している。602はウエハチ
ャックである。FIG. 6 is a perspective view of a main part of a semiconductor exposure apparatus to which the second embodiment according to the present invention is applied. The same members as those in FIG. 1 are denoted by the same reference numerals. The main components are the same as those in the first embodiment. In this embodiment, two semiconductor lasers 10-1 and 10- having different oscillation center wavelengths are used as light sources in the alignment head.
2 were provided. The optical paths of the light beams from the semiconductor lasers 10-1 and 10-2 are adjusted so that the chief rays overlap when emitted by the half mirror 12a. Reference numeral 600 denotes a stage, which is driven by a stage driver 601 in the X, Y, and Z directions. 602 is a wafer chuck.
CPU9は前述の実施例で説明した波長変更の際に点灯す
る半導体レーザを切り換える。即ち交互に点灯させる
(同時でも良い)ことにより照射用光束の波長変更を実
行している。これはそれぞれの半導体レーザの前にシャ
ッタを設け、交互にシャッタを開閉するように制御して
も良い。The CPU 9 switches the semiconductor laser that is turned on when the wavelength is changed as described in the above-described embodiment. That is, the wavelength of the irradiating light beam is changed by alternately turning on (or simultaneously). In this case, a shutter may be provided before each semiconductor laser, and the shutter may be opened and closed alternately.
半導体レーザ10−1の中心波長830nm、半導体レーザ1
0−2の中心波長は780nmで、グレーティングレンズの設
計方程式は波長が805nmのアライメント光に適用すると
仮定して、パラメータの設定を行った。このとき波長変
調率はΔλ/λ=6.2×10-2。830 nm center wavelength of semiconductor laser 10-1, semiconductor laser 1
The parameters were set on the assumption that the center wavelength of 0-2 is 780 nm and the design equation of the grating lens is applied to alignment light having a wavelength of 805 nm. At this time, the wavelength modulation rate is Δλ / λ = 6.2 × 10 −2 .
マスク2のグレーティングレンズ5の焦点距離f、マ
スク、ウエハ間隔gは第1実施例と同じとし、波長805n
mの光束に対し、グレーティングレンズ系のギャップ検
出倍率Aが80.6になるとすると、倍率変動幅ΔAは5.33
となる。The focal length f of the grating lens 5 of the mask 2 and the distance g between the mask and the wafer are the same as in the first embodiment.
Assuming that the gap detection magnification A of the grating lens system is 80.6 for the light flux of m, the magnification fluctuation width ΔA is 5.33.
Becomes
本発明に係る第3の実施例を適用した半導体露光装置
の要部斜視図を第7図に示す。本実施例では光源とし
て、白色光源703を用い、波長選択手段として回折格子1
3及びスリット板14をアライメントヘッド706内に設定し
ている。回折格子13は入射光束に対し、その入射角を変
化させることにより各波長毎に回折光の出射角が変動す
る。回折光を受光可能な所定位置にスリット・ピンホー
ル等を設けたスリット板14を配置し、回折格子13を入射
角が変化するように回転させることによってスリット板
14を通過する光束の波長を変化させることができる。従
ってCPU9は前述の実施例で説明した波長変更の際に、回
折格子13を所定の角度回転させることによって照射用光
束の波長変更を実行している。FIG. 7 is a perspective view of a main part of a semiconductor exposure apparatus to which the third embodiment according to the present invention is applied. In this embodiment, a white light source 703 is used as a light source, and a diffraction grating 1 is used as a wavelength selection unit.
3 and the slit plate 14 are set in the alignment head 706. The diffraction grating 13 changes the incident angle with respect to the incident light beam, so that the emission angle of the diffracted light changes for each wavelength. A slit plate 14 provided with slits, pinholes, and the like is arranged at a predetermined position capable of receiving diffracted light, and the slit plate is rotated by rotating the diffraction grating 13 so that the incident angle changes.
The wavelength of the light beam passing through 14 can be changed. Therefore, the CPU 9 changes the wavelength of the irradiation light beam by rotating the diffraction grating 13 by a predetermined angle when changing the wavelength described in the above-described embodiment.
本実施例のようにコピーレンシーの低い光源を用いる
ことにより、ウエハ3面上のレジスト表面粗をマスク、
ウエハ上のアライメントマークのエッジからの散乱光等
の要因により発生する受光面8a上のスペクトルなどの不
要光を抑えることができる。By using a light source having a low copy reliability as in the present embodiment, the resist surface roughness on the surface of the wafer 3 is masked,
Unnecessary light such as a spectrum on the light receiving surface 8a generated by factors such as scattered light from the edge of the alignment mark on the wafer can be suppressed.
尚、波長選択手段としては回折格子を用いることに限
定されることなく、例えばプリズム、色フィルターなど
を用いてもよい。又波長選択手段は光源703のすぐ後で
はなく、受光手段8の検出面8aの直前に配置し、白色光
をグレーティングに照射し、グレーティングレンズ5で
回折された光束を波長選択手段によって検出したい波長
のみ検出面上に入射させるように制御してもよい。この
場合スリット板14はマスク、ウエハいずれによって光束
の出射角が変動しても、マスクとウエハとが所定の位置
ずれ範囲内にあれば、検出用の波長の光が遮光されない
ようにスリットの大きさを設定しておく。Note that the wavelength selection means is not limited to using a diffraction grating, and for example, a prism, a color filter, or the like may be used. The wavelength selecting means is arranged not immediately after the light source 703 but immediately before the detection surface 8a of the light receiving means 8, irradiates the grating with white light, and detects a light beam diffracted by the grating lens 5 by the wavelength selecting means. Control may be performed so that only the light enters the detection surface. In this case, even if the exit angle of the light beam is changed by the mask or the wafer, if the mask and the wafer are within a predetermined positional deviation range, the slit plate 14 has a size of the slit so that the light of the wavelength for detection is not blocked. Set the value.
(発明の効果) 本発明によれば第1物体面上に前述のような波面変換
素子を設け、これに異なる波長成分有する複数の光束を
照射し、該波面変換素子によって偏向された光束を利用
することにより、第2物体が第1物体に対して傾いて
も、又光源手段からの光束照射や受光手段等に位置変化
が生じても検出誤差の発生を少なくした高精度な間隔測
定が可能な特に半導体製造装置に好適な間隔測定装置を
達成することができる。(Effects of the Invention) According to the present invention, the above-described wavefront conversion element is provided on the first object surface, and a plurality of light beams having different wavelength components are irradiated on the wavefront conversion element, and the light beam deflected by the wavefront conversion element is used. By doing so, even if the second object is tilted with respect to the first object, or even if the position of the light beam irradiation from the light source means or the position of the light receiving means changes, high-accuracy interval measurement with less occurrence of detection errors is possible. In particular, an interval measuring device suitable for a semiconductor manufacturing apparatus can be achieved.
第1図は本発明の一実施例の光学系の概略図、第2図は
第1図のマスクとウエハに入射する光束の説明図、第3
図(A),(B),(C)のマスク面上の物理光学素子
の機能を示す説明図、第4図(A),(B)は本発明の
他の一実施例の一部分を概略図、第5図は本発明に係る
間隔設定の手順を示すフローチャート図、第6,第7図は
各々本発明の一実施例の概略図、第8図は従来の間隔測
定装置の概略図である。第9図は本発明においてウエハ
が傾いたときの間隔測定における光路の説明図である。 図中、1は光束、2はマスク、3はウエハ、4,104は第
1物理光学素子、5は第2物理光学素子、61,62は回折
光、7,105は集光レンズ、8,106は受光手段、9は信号処
理回路、10は光ブローブ、15はコリメーターレンズ、16
はハーフミラー、17は注入電流制御手段、LDは光源であ
る。FIG. 1 is a schematic view of an optical system according to an embodiment of the present invention, FIG. 2 is an explanatory view of a light beam incident on the mask and the wafer of FIG.
4A, 4B, and 4C are explanatory views showing the function of the physical optical element on the mask surface, and FIGS. 4A and 4B schematically show a part of another embodiment of the present invention. FIG. 5, FIG. 5 is a flow chart showing the procedure of the interval setting according to the present invention, FIGS. 6 and 7 are schematic diagrams of one embodiment of the present invention, and FIG. 8 is a schematic diagram of a conventional interval measuring device. is there. FIG. 9 is an explanatory view of an optical path in the interval measurement when the wafer is tilted in the present invention. In the figure, 1 is a light beam, 2 is a mask, 3 is a wafer, 4,104 is a first physical optical element, 5 is a second physical optical element, 61 and 62 are diffracted lights, 7,105 is a condenser lens, 8,106 is a light receiving means, and 9 is a light receiving means. Is a signal processing circuit, 10 is an optical probe, 15 is a collimator lens, 16
Is a half mirror, 17 is an injection current control means, and LD is a light source.
Claims (5)
とを対向配置し、該第1物体上の波面変換素子に光源手
段から複数の波長の光束を同時又は順次照射し、該波面
変換素子によって所定方向に偏向した光を該第2物体面
で反射させた後、受光手段面上に導光し、該受光手段面
上における少なくとも2つの波長の光の入射位置を個別
に検出することにより、該第1物体と第2物体との間隔
を求めたことを特徴とする間隔測定装置。A first object provided with a wavefront converting element and a second object disposed opposite to each other, and simultaneously irradiating the wavefront converting element on the first object with light beams of a plurality of wavelengths from a light source means; After the light deflected in a predetermined direction by the wavefront conversion element is reflected by the second object surface, the light is guided on the light receiving means surface, and the incident positions of at least two wavelengths of light on the light receiving means surface are individually detected. An interval measurement device for determining an interval between the first object and the second object by performing the operation.
子とを設けた第1物体と第2物体とを対向配置し、該第
1物体面上の第1波面変換素子に光源手段から複数の波
長の光束を同時又は順次照射し、該第1波面変換素子か
らの所定次数の回折光を該第2物体で反射させた後、該
第1物体面上の第2波面変換素子に入射させ、該第2波
面変換素子からの所定次数の回折光を受光手段面上に導
光し、該受光手段面上における少なくとも2つの波長の
回折光の入射位置を個別に検出することにより、該第1
物体と第2物体との間隔を求めたことを特徴とする間隔
測定装置。2. A first object and a second object, which are partially provided with a first wavefront conversion element and a second wavefront conversion element, are arranged opposite to each other, and a light source is provided to the first wavefront conversion element on the first object plane. Means for simultaneously or sequentially irradiating light beams of a plurality of wavelengths, and diffracting light of a predetermined order from the first wavefront conversion element by the second object, and then applying a second wavefront conversion element on the first object plane And diffracted light of a predetermined order from the second wavefront conversion element is guided on the light receiving means surface, and the incident positions of the diffracted lights of at least two wavelengths on the light receiving means surface are individually detected. , The first
An interval measuring device, wherein an interval between an object and a second object is obtained.
変調されたグレーティング素子であることを特徴とする
請求項2記載の間隔測定装置。3. An interval measuring apparatus according to claim 2, wherein said second wavefront conversion element is a grating element whose pitch is spatially modulated.
波長差が大きいときは同時に、波長差が小さいときは順
次照射するようにしたことを特徴とする請求項1又は2
記載の間隔測定装置。4. A light source according to claim 1, wherein said light source means simultaneously emits light when a wavelength difference between a plurality of light beams is large and sequentially emits light when said wavelength difference is small.
The distance measuring device as described.
用いて、第1物体と第2物体との間隔を所定値にして該
第1物体面上のパターンを第2物体面上に露光転写して
いることを特徴とする露光装置。5. The method according to claim 1, wherein the distance between the first object and the second object is set to a predetermined value, and the pattern on the first object surface is converted to a second object. An exposure apparatus, wherein exposure transfer is performed on a surface.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2136827A JP2874284B2 (en) | 1990-05-25 | 1990-05-25 | Interval measuring device |
US07/562,656 US5114236A (en) | 1989-08-04 | 1990-08-03 | Position detection method and apparatus |
DE69013790T DE69013790T2 (en) | 1989-08-04 | 1990-08-03 | Method and device for determining position. |
EP90308601A EP0411966B1 (en) | 1989-08-04 | 1990-08-03 | Position detection method and apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2136827A JP2874284B2 (en) | 1990-05-25 | 1990-05-25 | Interval measuring device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0431703A JPH0431703A (en) | 1992-02-03 |
JP2874284B2 true JP2874284B2 (en) | 1999-03-24 |
Family
ID=15184433
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2136827A Expired - Fee Related JP2874284B2 (en) | 1989-08-04 | 1990-05-25 | Interval measuring device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2874284B2 (en) |
-
1990
- 1990-05-25 JP JP2136827A patent/JP2874284B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JPH0431703A (en) | 1992-02-03 |
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