JPH116714A - Method for detecting height of sample surface and apparatus therefor - Google Patents
Method for detecting height of sample surface and apparatus thereforInfo
- Publication number
- JPH116714A JPH116714A JP10150922A JP15092298A JPH116714A JP H116714 A JPH116714 A JP H116714A JP 10150922 A JP10150922 A JP 10150922A JP 15092298 A JP15092298 A JP 15092298A JP H116714 A JPH116714 A JP H116714A
- Authority
- JP
- Japan
- Prior art keywords
- light
- sample
- height
- detecting
- image
- 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
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
- G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
- G03F9/7023—Aligning or positioning in direction perpendicular to substrate surface
- G03F9/7026—Focusing
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、試料表面の高さを
光学的に検出する方法及びその装置に関する。The present invention relates to a method and an apparatus for optically detecting the height of a sample surface.
【0002】[0002]
【従来の技術】従来の半導体ウエハ等の表面の傾き検出
装置は第1の公知例である特開昭61−170605号
公報に記載のよう図8のレーザダイオード2を出射した
光をレンズ14により指向性のビームとしウエハ4に上
方より照射し、反射光を2次元位置検出器20で位置検
出するものである。2. Description of the Related Art A conventional device for detecting the inclination of a surface of a semiconductor wafer or the like is disclosed in Japanese Patent Application Laid-Open No. 61-170605, which is a first known example, in which light emitted from a laser diode 2 shown in FIG. The directional beam is applied to the wafer 4 from above, and the reflected light is detected by the two-dimensional position detector 20.
【0003】また計測対象を光学的多層構造物体に限ら
ず一般的対象の距離(高さ)及び傾き計測装置は第2の
公知例である図9の特開昭62−218802号公報に
示されている。この公知例では傾きについては垂直に入
射し、第1の公知例と同様第2の受光器で求められ、距
離(被測定物6の面に垂直方向)は第1の光路9により
入射角60°程度で照射されたスポットを第1の検出器
上に結像し、その結像位置から求めている。A measuring device for measuring the distance (height) and inclination of a general object is not limited to an optical multi-layer structure object, but is shown in a second known example of Japanese Patent Application Laid-Open No. 62-218802 in FIG. ing. In this known example, the inclination is perpendicularly incident, and the inclination is obtained by the second light receiving device as in the first known example. The distance (in the direction perpendicular to the surface of the DUT 6) is 60 ° by the first optical path 9. The spot illuminated at about ° is imaged on the first detector and obtained from the imaged position.
【0004】[0004]
【発明が解決しようとする課題】上記従来技術は半導体
ウエハ等ウエハ表面上に薄膜構造で形成されたパターン
や、その上にフォトレジストを1〜数μmの厚さで塗布
されたものに適用すると照射光は被測定物の表面で反射
するだけでなく、屈折して層構造の内部にも入射し、下
地層で反射した光が、再び表面を通り、上記の最上面で
反射した光に重畳される。この際最上面と下地面で反射
した光は互に干渉しあい、膜の厚さと照射光の入射角度
の微小な変化に対し干渉強度が大きく変化する。図8や
図9の距離を検出する系のように斜めより照射すると図
4に示すように被測定物体からの反射光の分布は入射時
の分布(例えばガウス分布)とは異なったものとなり、
しかも、被測定物体の層構造や、それを構成する物質の
光学定数により分布は異って来る。この結果、被測定物
が異なるたびに測定データにオフセットが発生し、正確
な絶対値測定が困難になる。また図9の傾き検出では垂
直に照射しているが、傾きや高さ検出を半導体露光装置
や、半導体パターン検査装置に適用しようとすると、露
光光学系や検出光学系と照射光学系が重なり、光学系の
構成が難しくなる。The above prior art is applied to a pattern formed in a thin film structure on a wafer surface such as a semiconductor wafer, or a pattern in which a photoresist is applied thereon with a thickness of 1 to several μm. Irradiation light is not only reflected on the surface of the object to be measured, but also refracted and enters the inside of the layer structure, and the light reflected on the underlayer passes through the surface again and is superimposed on the light reflected on the top surface described above. Is done. At this time, the light reflected by the uppermost surface and the light reflected by the base surface interfere with each other, and the interference intensity greatly changes with a minute change in the film thickness and the incident angle of the irradiation light. When the light is obliquely irradiated as in the systems for detecting the distance in FIGS. 8 and 9, the distribution of the reflected light from the object to be measured is different from the distribution at the time of incidence (for example, Gaussian distribution) as shown in FIG.
In addition, the distribution varies depending on the layer structure of the object to be measured and the optical constants of the materials constituting the layer structure. As a result, an offset is generated in the measurement data every time the object to be measured is different, and it is difficult to accurately measure an absolute value. In addition, in the inclination detection of FIG. 9, the irradiation is performed vertically, but if the inclination and height detection are applied to a semiconductor exposure apparatus or a semiconductor pattern inspection apparatus, the exposure optical system and the detection optical system overlap with the irradiation optical system, The configuration of the optical system becomes difficult.
【0005】上述の光学的多層物体の干渉による測定誤
差の発生は特に干渉方式により被測定物の表面の傾きや
高さを測定する場合に顕著に問題となる。干渉方式の場
合被測定物の表面で反射した光と参照光とで発生する干
渉縞から反射光の波面の傾きや位相を求め、これが被測
定物の傾きや高さを表わすことになる。しかし多層構造
物の場合、図4に示すように被測定物に0〜85°程度
の通常の入射角度で入射すると多層構造物体の表面や内
部の各層間で反射した光が干渉し、被測定物反射直後の
光の振幅や位相は各層の厚さや、その場所による変化に
より大きく変化を受ける。この結果参照光を重畳して得
る干渉縞は正確な正弦波形とならず、大きな誤差を発生
してしまう。[0005] The occurrence of measurement errors due to the interference of the optical multilayer object described above becomes a serious problem particularly when measuring the inclination or height of the surface of the object to be measured by the interference method. In the case of the interference method, the slope and phase of the wavefront of the reflected light are obtained from the interference fringes generated by the light reflected on the surface of the object and the reference light, and this represents the inclination and height of the object. However, in the case of a multi-layered structure, as shown in FIG. 4, when the light is incident on the measured object at a normal incident angle of about 0 to 85 °, the light reflected between the surfaces of the multi-layered structure and between the layers inside the multi-layered structure interferes. The amplitude and phase of light immediately after the reflection of an object greatly changes depending on the thickness of each layer and the change depending on the location. As a result, an interference fringe obtained by superimposing the reference light does not have an accurate sine waveform, and a large error occurs.
【0006】本発明の目的は上記従来の課題を解決し、
半導体ウエハ等の物体の高さを被測定物体の構造や光特
性に関係なく、正確に測定することができるようにした
試料表面の高さ検出方法及びその装置を提供することに
ある。An object of the present invention is to solve the above-mentioned conventional problems,
It is an object of the present invention to provide a method and apparatus for detecting the height of a sample surface, which can accurately measure the height of an object such as a semiconductor wafer regardless of the structure and optical characteristics of the object to be measured.
【0007】また、本発明の目的は露光装置や、検査装
置に実装容易にすることにある。Another object of the present invention is to make it easy to mount the apparatus on an exposure apparatus or an inspection apparatus.
【0008】[0008]
【課題を解決するための手段】上記目的を達成するため
に、本発明においては被測定物体の表面に、比較的指向
性の高い光を、その主光線の入射角が85°以上になる
ように斜めより照射する。入射角度が85°以上になる
と図5,図6に示すように入射光の振幅に対する反射光
の振幅の比は小さくなり、ほとんどの光が表面で反射
し、内部への入射は僅かになる。更に照射する光の振幅
をS偏光にすると表面での反射は益々大きくなり、主光
線の入射角は82°以上であればよい。In order to achieve the above object, in the present invention, light having a relatively high directivity is applied to the surface of an object to be measured so that an incident angle of a principal ray of the light is 85 ° or more. Irradiate diagonally. When the incident angle is 85 ° or more, the ratio of the amplitude of the reflected light to the amplitude of the incident light becomes smaller as shown in FIGS. 5 and 6, most of the light is reflected on the surface, and the light entering the interior becomes slightly. Further, when the amplitude of the irradiated light is S-polarized, the reflection on the surface is further increased, and the incident angle of the principal ray may be 82 ° or more.
【0009】被測定物体に入射する照射光の正反射の方
向は被測定物体の傾きαに対し2αとなる。この正反射
光をほぼ垂直に反射させ元の光路に戻し、再び被測定物
に入射させると、図12に示すように正反射光は4αと
なる。即ち被測定物の傾きの4倍の傾きが正反射光に生
じることになる。The direction of the regular reflection of the irradiation light incident on the object to be measured is 2α with respect to the inclination α of the object to be measured. When the specularly reflected light is reflected almost vertically, returned to the original optical path, and made incident again on the device under test, the specularly reflected light becomes 4α as shown in FIG. That is, an inclination four times the inclination of the object to be measured occurs in the specularly reflected light.
【0010】更に本発明では傾きや高さを検出する方法
として干渉を用いる場合、前述した干渉法を用いる従来
の課題に対し、表面での反射を大きくすることにより正
反射光の振幅や位相はほとんど表面の情報を表わすこと
になり、内部の層の厚さやパターン段差の影響を受けな
くなる。Further, in the present invention, when interference is used as a method for detecting the inclination or height, the amplitude and phase of the specularly reflected light are increased by increasing the reflection on the surface, as opposed to the conventional problem using the above-described interference method. It almost represents the surface information, and is not affected by the thickness of the inner layer or the pattern step.
【0011】被測定物体に入射する光の振幅をS偏光、
P偏光に対しAS,APとすると、屈折率nの物体の表面
で反射及び屈折する光の振幅RS,RPおよびDS,DPは
入射角θ、屈折角ψ(sinψ=sinθ/n)に対
し、以下の式で与えられる。The amplitude of light incident on the object to be measured is S-polarized light,
Assuming that AS and AP are P-polarized light, the amplitudes RS and RP and DS and DP of the light reflected and refracted on the surface of the object having the refractive index n are: incident angle θ and refraction angle ψ (sinψ = sin θ / n) It is given by the following equation.
【0012】[0012]
【数1】 (Equation 1)
【0013】[0013]
【数2】 (Equation 2)
【0014】[0014]
【数3】 (Equation 3)
【0015】[0015]
【数4】 (Equation 4)
【0016】S偏光では入射角が0°から60°、P偏
光では0°から75°程度までは表面反射光より透過光
の方が大きく、下地の多層構造の境界からの反射光より
表面反射光との間で振幅の大きな干渉が発生する。入射
角が上記値から85°程度までは表面反射光の振幅の方
が大きくなるが、正確な測定を実施するには不十分な条
件である。以下にその理由を示す。For S-polarized light, the transmitted light is larger than the surface reflected light from 0 ° to 60 ° for the incident angle of 0 ° to 75 ° for P-polarized light, and the surface reflected light is larger than the reflected light from the boundary of the underlying multilayer structure. Interference with light having large amplitude occurs. When the incident angle is from the above value to about 85 °, the amplitude of the surface reflected light becomes larger, but this is an insufficient condition for performing accurate measurement. The reasons are as follows.
【0017】図3に示すように入射角θで入射した振幅
Aの光は屈折角ψ、振幅Dで屈折し、下地で振幅反射率
Rbで反射すると、この反射光の振幅はD・Rbとなる。
ここで入射光Aの振幅を1とするとDは振幅透過率にな
る。従って下地で反射した光が表面を通過するとその振
幅はRb・D2となる。他方振幅A(=1)で入射した光
は表面で反射しその振幅はRとなる。ここでRやDは入
射光の偏光がSかPかでRS,DS及びRP,DPで表わせ
ば上記(数1)〜(数4)が成立する。表面で反射した
光R0と下地で反射した光R1は層の厚さdが薄いと重な
り、その結果次式で示す複素振幅ARの光となる。As shown in FIG. 3, light having an amplitude A incident at an incident angle θ is refracted at a refraction angle ψ and an amplitude D, and is reflected at a base with an amplitude reflectance Rb, the amplitude of the reflected light becomes D · Rb. Become.
Here, assuming that the amplitude of the incident light A is 1, D becomes the amplitude transmittance. Therefore, when the light reflected by the base passes through the surface, its amplitude becomes Rb · D 2 . On the other hand, the light incident with the amplitude A (= 1) is reflected by the surface and the amplitude becomes R. Here, R and D are expressed by RS, DS and RP, DP depending on whether the polarization of the incident light is S or P, and the above (Equation 1) to (Equation 4) hold. The light R0 reflected by the surface and the light R1 reflected by the base overlap when the thickness d of the layer is small, resulting in light having a complex amplitude AR represented by the following equation.
【0018】[0018]
【数5】 (Equation 5)
【0019】但しここでλは測定に用いる光の波長であ
る。Here, λ is the wavelength of light used for measurement.
【0020】図3に示す膜の厚さdは僅かな変化(波長
の1桁下の長さの変化)に対しても(数5)からARの
位相が変化することが分る。そこで入射角θとR,Dの
関係はS及びP偏光に対しそれぞれ図5及び図6に示す
通りであり、このグラフから更に分り易くするためノイ
ズ成分となる(数5)の第1項に対する第2項の振幅比
Rb・D2/Rを求めれば、測定に及ぼす誤差の程度を評
価することができる。そこで最悪のケースとしてRb=
1の場合を考え、D2/Rを入射角度θに対し、また2
つの偏光に対して求めたものが図7である。D2/Rは
各種検出方法において雑音(誤差)成分となるため、こ
の値を5%以下に保つには85°以上の入射角にする必
要があることが分る。またS偏光状態で入射すれば更に
雑音が小さくなり、上記値を5%以下に保つには、図7
からも分るように、82°以上であればよいことが(数
1)と(数2)とから求められる。It can be seen from FIG. 3 that even if the thickness d of the film shown in FIG. 3 changes slightly (change in the length one order of magnitude below the wavelength), the phase of AR changes from (Equation 5). Therefore, the relationship between the incident angle θ and R and D is as shown in FIG. 5 and FIG. 6 for S and P polarized light, respectively. By obtaining the amplitude ratio Rb · D 2 / R of the second term, it is possible to evaluate the degree of an error exerted on the measurement. So, in the worst case, Rb =
Considering the case of 1, the ratio D 2 / R to the incident angle θ, and 2
FIG. 7 shows the results obtained for two polarized lights. Since D 2 / R is a noise (error) component in various detection methods, it can be seen that in order to keep this value at 5% or less, the incident angle must be 85 ° or more. If the light is incident in the S-polarized state, the noise is further reduced.
As can be seen from (Equation 1) and (Equation 2), it is sufficient that the angle should be 82 ° or more.
【0021】被測定物体表面で2度反射させる方法は前
述した様に傾きと高さの検出感度を向上させることにな
り、精度の高い測定を可能にする。The method of reflecting twice on the surface of the object to be measured improves the inclination and height detection sensitivity as described above, and enables highly accurate measurement.
【0022】また干渉法による検出では下地面からの反
射光は干渉パターンに重畳し干渉縞のピッチや位相を乱
すが、85°以上の入射によりまた更にS偏光を用いる
ことにより前述した通りほとんどこの影響を除くことが
可能となり、精度の高い検出が可能となる。更にこの干
渉測定に用いる参照光の光路を測定光とほぼ同一の光路
にすることにより空気のゆらぎ等の測定環境の影響をほ
とんど受けない安定で高精度の測定を実現する。In the detection by the interference method, the reflected light from the ground surface is superimposed on the interference pattern and disturbs the pitch and phase of the interference fringes. The influence can be eliminated, and highly accurate detection can be performed. Further, by setting the optical path of the reference light used for the interference measurement to be substantially the same as the optical path of the measurement light, stable and high-precision measurement hardly affected by the measurement environment such as the fluctuation of air is realized.
【0023】上述の傾き及び高さ測定方法を半導体露光
装置に適用すると、露光光学系との空間的干渉がなく、
しかも上記のように高精度にウエハの露光部分の傾きと
高さを検出することが可能なため、この検出値から、ウ
エハの傾きや高さを制御し、露光結像面にウエハの表面
を精密に合せることができ、サブミクロンパターンを露
光領域全面に亘り、正確に焼付けることが可能となる。When the above-described tilt and height measuring method is applied to a semiconductor exposure apparatus, there is no spatial interference with the exposure optical system, and
Moreover, since the tilt and height of the exposed portion of the wafer can be detected with high accuracy as described above, the tilt and height of the wafer are controlled based on the detected values, and the surface of the wafer is formed on the exposure image forming surface. The submicron pattern can be precisely printed over the entire exposure area.
【0024】[0024]
【発明の実施の形態】以下、本発明の一実施例を図1に
示す。図1は半導体露光装置の露光状態にありウエハの
露光領域の傾きを検出するものである。81は露光照明
系、9はレチクルであり、8は縮小露光レンズであり、
レチクル9のパターンがウエハ4上に露光される。この
際ウエハ表面に塗布されたフォトレジストの面は、ウエ
ハのうねり、厚さむら、ウエハチャックの平面性等によ
り必ずしも平面でない。そこで1の半導体レーザから出
射したレーザ光をコリメートレンズ11により細い平行
ビームとし、ミラー13を介しウエハのレジスト表面の
しかも露光領域に85°以上の入射角で入射する。反射
した光はミラー210、集光レンズ20により、光位置
検出器3′上に集光させ、その集光位置を検出する。露
光領域がα傾いていると正反射光は2α傾くため集光レ
ンズの焦点距離をfとすると光位置検出器の集光スポッ
トは2αfずれる。従って、検出された信号は処理回路
5′に送られ、ウエハチャックを搭載したチルト機構を
駆動し、レチクルパターン像面にウエハ上のフォトレジ
スト面が一致する様に制御される。FIG. 1 shows an embodiment of the present invention. FIG. 1 is for detecting the inclination of an exposure area of a wafer in an exposure state of a semiconductor exposure apparatus. 81 is an exposure illumination system, 9 is a reticle, 8 is a reduction exposure lens,
The pattern of the reticle 9 is exposed on the wafer 4. At this time, the surface of the photoresist applied to the wafer surface is not necessarily flat due to the undulation of the wafer, uneven thickness, the flatness of the wafer chuck, and the like. Therefore, the laser light emitted from one semiconductor laser is converted into a narrow parallel beam by the collimating lens 11 and is incident on the resist surface of the wafer and at an exposure angle of 85 ° or more via the mirror 13. The reflected light is condensed on the light position detector 3 'by the mirror 210 and the condensing lens 20, and the condensing position is detected. If the exposure area is inclined by α, the specularly reflected light is inclined by 2α, so that if the focal length of the condenser lens is f, the focal spot of the optical position detector is shifted by 2αf. Therefore, the detected signal is sent to the processing circuit 5 'to drive the tilt mechanism equipped with the wafer chuck, so that the photoresist surface on the wafer is controlled to coincide with the reticle pattern image surface.
【0025】この際半導体レーザ出射光161′がウエ
ハ面にS偏光で入射するように半導体レーザを配置すれ
ば前述したごとくより正確な傾き検出が可能になる。図
1の実施例では光位置検出器3′はx,y両方向を検出
するタイプであり、一つの検出系で2方向の傾きを求め
ることができる。At this time, if the semiconductor laser is arranged so that the semiconductor laser emission light 161 'is incident on the wafer surface as S-polarized light, more accurate tilt detection becomes possible as described above. In the embodiment of FIG. 1, the optical position detector 3 'is of a type that detects both the x and y directions, and one detection system can determine the inclination in two directions.
【0026】図1で紙面と垂直な方向に第2の検出系を
設け、xとyの方向の傾きを別々に検出してもよい。ま
た光源は比較的指向性の高い光をウエハに照射できれば
半導体レーザに限らない。In FIG. 1, a second detection system may be provided in a direction perpendicular to the plane of the drawing to separately detect inclinations in the x and y directions. The light source is not limited to a semiconductor laser as long as it can irradiate the wafer with light having relatively high directivity.
【0027】図2は本発明の一実施例であり、図1と同
一番号は同一物を表す。半導体レーザ1を出射した光は
入射角85°以上でウエハに入射し集光レンズ11′に
より光源像がウエハ上の露光領域内に形成される。反射
した光はミラー210、レンズ21,22により光位置
検出器3′′上に集光される。ウエハ表面が露光光学系
のレジストパターン結像位置にあれば光位置検出器
3′′の中心に、上下にずれれば光位置検出器3′′の
中心から左右にずれるため、光位置検出器3′′の検出
信号を処理回路5′に送り、ウエハ上下テーブルを駆動
制御すれば、常に正しい焦点合せが可能となる。レーザ
光の偏光をウエハ面にS偏光で入射するように構成すれ
ばより正確にフォトレジスト表面の高さを求めることが
可能となる。FIG. 2 shows an embodiment of the present invention. The same reference numerals as those in FIG. 1 denote the same parts. The light emitted from the semiconductor laser 1 is incident on the wafer at an incident angle of 85 ° or more, and a light source image is formed in the exposure area on the wafer by the condenser lens 11 ′. The reflected light is collected on the optical position detector 3 '' by the mirror 210 and the lenses 21 and 22. If the wafer surface is at the resist pattern image forming position of the exposure optical system, it is shifted to the center of the optical position detector 3 ''. By sending the detection signal 3 '' to the processing circuit 5 'and controlling the drive of the wafer upper and lower tables, correct focusing can always be performed. If the polarization of the laser beam is incident on the wafer surface as S-polarized light, the height of the photoresist surface can be determined more accurately.
【0028】図10は本発明の一実施例であり、図1と
同一部品番号は同一物を表わしている。コリメートレン
ズ11により得られた平行光はビームスプリッタ19′
を通り、ウエハのフォトレジスト面に85°以上の入射
角例えば87°で入射する。正反射した光は平面鏡14
にほぼ垂直に入射し、反射光は再びフォトレジスト面で
正反射し、ビームスプリッタ19′で反射され集光レン
ズ20により光位置検出器3′上に集光され、集光スポ
ットの位置が検出される。ウエハへの入射角を87°と
し図11に示すようにS偏光16Sになる様にすると図
7に示すようにDS2/RSは0.0065、即ち0.6
5%となり、ほとんどフォトレジスト内に入る光162
1は無視できるようになり、図11に示すように下地層
が凸凹しているも、その影響は全くほとんど受けず、平
行光のまま正反射する。従って光位置検出器3′には集
光度の高い鋭いスポット光が得られる。更に本実施例で
は図12に示すように平面鏡14で垂直に反射され、再
びウエハに入射するため、ウエハが4から4′にαだけ
傾くと、最終的に光位置検出器に戻って来る光は4α傾
くことになり、図1の実施例に比べ2倍高い感度で光位
置を検出することが可能となる。この結果S/N、感度
とも従来に比べ非常に優れた傾き検出が可能となる。FIG. 10 shows an embodiment of the present invention, and the same reference numerals as those in FIG. 1 denote the same parts. The parallel light obtained by the collimator lens 11 is converted into a beam splitter 19 '.
And incident on the photoresist surface of the wafer at an incident angle of 85 ° or more, for example, 87 °. The specularly reflected light is a plane mirror 14
, And the reflected light is specularly reflected again at the photoresist surface, reflected by the beam splitter 19 ′, and condensed on the optical position detector 3 ′ by the condenser lens 20, and the position of the condensed spot is detected. Is done. When the incident angle on the wafer is 87 ° and the S-polarized light is 16S as shown in FIG. 11, DS2 / RS is 0.0065, that is, 0.6 as shown in FIG.
5%, light 162 almost entering the photoresist
1 becomes negligible, and although the underlying layer is uneven as shown in FIG. 11, the influence is hardly affected at all, and the light is specularly reflected as parallel light. Therefore, a sharp spot light having a high light condensing degree is obtained at the light position detector 3 '. Further, in this embodiment, as shown in FIG. 12, the light is vertically reflected by the plane mirror 14 and re-enters the wafer. Therefore, when the wafer is tilted from 4 to 4 'by .alpha., The light finally returning to the optical position detector Is inclined by 4α, and the light position can be detected with twice the sensitivity as compared with the embodiment of FIG. As a result, it is possible to detect a tilt which is very excellent in both S / N and sensitivity as compared with the related art.
【0029】図13は本発明の一実施例であり、図2と
同一番号は同一物を表す。集光レンズ11′で得られた
集光ビームはウエハ上の照射位置Aでほぼ集光する。入
射角度は85°以上である。正反射光はコリメートレン
ズ141により平行光にされ、平面鏡14にほぼ垂直に
入射する。反射光は往路とほぼ同一光路を通り、ウエハ
上でほぼ集光し、再び反射し、ビームスプリッタ12を
通過し、集光レンズ22により光位置検出器3′′上に
集光される。図14は実線で示したウエハの表面(反射
面Σ)4が点線の4′(反射面Σ)に変化した場合のウ
エハ近傍の集光点の位置を説明している。反射面がΣの
時には往路、復路ともA点に集光する場合について考え
る。反射面がΣ′の時にはΣ′面が鏡面となり、往路の
A点はA′点に鏡像を作る。このA′点から出た光はレ
ンズ141平面鏡14により、復路ではA′′に集光す
る。この集光点はΣ′が鏡面となりA′′′にA′′点
の鏡像を作る。従って復路からはあたかもA′′′から
光が出射するごとく集光レンズ22入射し、光位置検出
器3′′にはA′′′の像位置に光が集光する。Σと
Σ′の距離、即ちウエハの上下移動量をΔhとするとFIG. 13 shows an embodiment of the present invention. The same reference numerals as those in FIG. 2 denote the same parts. The condensed beam obtained by the condensing lens 11 'is almost condensed at the irradiation position A on the wafer. The incident angle is 85 ° or more. The specularly reflected light is collimated by the collimating lens 141 and is incident on the plane mirror 14 almost perpendicularly. The reflected light passes through substantially the same optical path as the outward path, is substantially condensed on the wafer, is reflected again, passes through the beam splitter 12, and is condensed on the optical position detector 3 '' by the condensing lens 22. FIG. 14 illustrates the position of the condensing point near the wafer when the surface (reflection surface Σ) 4 of the wafer indicated by the solid line changes to the dotted line 4 ′ (reflection surface Σ). Consider the case where light is condensed at point A when the reflection surface is Σ for both the forward path and the return path. When the reflection surface is Σ ', the Σ' surface becomes a mirror surface, and point A on the outward path forms a mirror image at point A '. The light emitted from the point A 'is condensed on the return path A''by the lens 141 plane mirror 14. This condensing point becomes a mirror surface of Σ ′ and forms a mirror image of the A ″ point at A ′ ″. Accordingly, from the return path, the light enters the condenser lens 22 as if the light exits from A '''', and the light is focused on the image position of A '''' on the light position detector 3 ''. If the distance between Σ and Σ ', that is, the amount of vertical movement of the wafer is Δh,
【0030】[0030]
【数6】 (Equation 6)
【0031】となり、復路の発光点位置はウエハの変位
量の4倍(4Δh)シフトする(図14参照)。この結
果図2の実施例に比べ2倍の変位量が光位置検出器
3′′で検出される。この結果高感度でS/Nの高い高
さ検出が可能となる。Then, the light emitting point position on the return path is shifted by four times (4Δh) the displacement amount of the wafer (see FIG. 14). As a result, a displacement amount twice as large as that in the embodiment of FIG. 2 is detected by the optical position detector 3 ''. As a result, height detection with high sensitivity and high S / N becomes possible.
【0032】図15は本発明の一実施例図である。図1
と同一番号は同一物を表わしている。レーザ等可干渉性
光源1を出射した光はコリメータレンズ11により平行
光15となりプリズム10に入射する。プリズム10は
入射光15を2つの平行ビーム16と17に分離する。
この2つの平行ビームは0点で重なる様に互に一定の角
度θ0−θ1が付いている。一方の平行ビーム16はウエ
ハに入射角θ1で入射し、他方は参照光でありウエハに
立てた垂線に対しθ0(>90°)の角度でウエハには
照射せずに進む。FIG. 15 is a diagram showing an embodiment of the present invention. FIG.
The same numbers indicate the same items. Light emitted from the coherent light source 1 such as a laser is converted into parallel light 15 by the collimator lens 11 and enters the prism 10. Prism 10 separates incident light 15 into two parallel beams 16 and 17.
The two parallel beams have a fixed angle θ0−θ1 so as to overlap at zero point. One of the parallel beams 16 is incident on the wafer at an incident angle θ1, and the other is reference light, which travels without irradiating the wafer at an angle of θ0 (> 90 °) with respect to a perpendicular to the wafer.
【0033】ウエハで反射した平行ビーム16は平面鏡
14にほぼ垂直に入射し、再びウエハに入射し、往路を
逆に辿り、ビームスプリッタ12で反射し、レンズ21
と22を通過後平行ビームとなり、一次元センサ3に入
射する。他方参照光は0点から直接平面鏡14にほぼ垂
直に入射し、反射後往路を逆に辿り、同じく一次元セン
サ3に入射し、ウエハで反射させた一方のビームとの間
で干渉縞を発生する。The parallel beam 16 reflected by the wafer is incident on the plane mirror 14 almost perpendicularly, re-enters the wafer, traces the outward path in reverse, is reflected by the beam splitter 12,
After passing through and, it becomes a parallel beam and enters the one-dimensional sensor 3. On the other hand, the reference light directly enters the plane mirror 14 almost perpendicularly from the point 0, follows the reverse path after reflection, and also enters the one-dimensional sensor 3 to generate an interference fringe with one of the beams reflected by the wafer. I do.
【0034】ウエハで反射させた光の復路にはピンホー
ル23と、楔ガラス26が配置されている。ピンホール
23は、参照光路にもあり、光学部品の裏面で反射した
ノイズ光を除去する役割を担っている。他方楔ガラス2
6はウエハで反射した光を屈折させることにより、一次
元センサ上でウエハ照射位置を結像させるとともに、参
照光と重なるようにしている。一次元センサ上にはセン
サのアレイ方向Xに対し図16図の実線で示されるよう
な強度の干渉縞が検出されている。ウエハ照射位置(X
=0)を中心にウエハが点線で示されるようにΔθ傾く
と、検出される干渉縞は図16の点線のようになる。即
ちX=0での強度はほとんど変化しないが、縞のピッチ
PからP′に変化する。即ちピッチPと傾きΔθの関係
は干渉縞の強度I(X)が(数7)で与えられるため、
この式から(数8)で求められる。A pinhole 23 and a wedge glass 26 are arranged on the return path of the light reflected by the wafer. The pinhole 23 is also in the reference optical path and plays a role of removing noise light reflected on the back surface of the optical component. Wedge glass 2
Numeral 6 refracts the light reflected from the wafer to form an image of the wafer irradiation position on the one-dimensional sensor and overlaps with the reference light. On the one-dimensional sensor, an interference fringe having an intensity as shown by a solid line in FIG. 16 in the sensor array direction X is detected. Wafer irradiation position (X
= 0), and the wafer is inclined by Δθ as shown by the dotted line, the detected interference fringes become as shown by the dotted line in FIG. That is, although the intensity at X = 0 hardly changes, it changes from the stripe pitch P to P ′. That is, the relationship between the pitch P and the slope Δθ is given by the following equation (7), where the intensity I (X) of the interference fringes is given by:
From this equation, it is obtained by (Equation 8).
【0035】[0035]
【数7】 (Equation 7)
【0036】[0036]
【数8】 (Equation 8)
【0037】上記(数7)でMはウエハ上の照射位置を
一次元センサに結像する倍率であるが、話を簡単にする
ため楔ガラスの楔角は0度と仮定している(楔ガラスが
ない場合)。In the above (Equation 7), M is the magnification at which the irradiation position on the wafer is imaged on the one-dimensional sensor. For the sake of simplicity, it is assumed that the wedge angle of the wedge glass is 0 ° (wedge). Without glass).
【0038】また(数7)のcosineの中の第2項はウエ
ハ面がΔZ変化した時の干渉縞の変化を表わしており、
図17に示すごとくウエハ面がΔZ変化すると干渉縞の
ピッチは変化せず位相がシフトする。従って本実施例で
は一次元センサ3で得られた干渉縞を処理回路5に送
り、ここで干渉縞ピッチと位相を求め得ることにより、
ウエハ面の高さと傾きが同時に求められることになる。
また本実施例では入射角度θ1を87〜89度に取るこ
とも可能であり、S偏光を照射光に用いれば図7からも
明らかなように下地多層構造の影響はほとんど受けず
に、傾きと高さを正確に求めることが可能となる。また
本実施例では参照光はウエハ照射光とほとんど同一の光
路を通っており、また使用光学部品もまたウエハ面での
反射を除き総て共通のため、空気のゆらぎ等の影響をほ
とんど受けずに安定な測定を実現することができる。The second term in cosine of (Equation 7) represents a change in interference fringes when the wafer surface changes by ΔZ.
As shown in FIG. 17, when the wafer surface changes by .DELTA.Z, the pitch of the interference fringes does not change and the phase shifts. Therefore, in the present embodiment, the interference fringes obtained by the one-dimensional sensor 3 are sent to the processing circuit 5, where the interference fringe pitch and phase can be obtained.
The height and inclination of the wafer surface are determined simultaneously.
Further, in this embodiment, the incident angle θ1 can be set to 87 to 89 degrees, and if S-polarized light is used for the irradiation light, as is apparent from FIG. The height can be determined accurately. Further, in this embodiment, the reference light passes through almost the same optical path as the wafer irradiation light, and the optical components used are also common except for the reflection on the wafer surface, so that they are hardly affected by air fluctuations and the like. A stable measurement can be realized.
【0039】[0039]
【発明の効果】以上説明したように本発明によれば、半
導体回路製作過程での様々の多層構造からなるウエハ等
光学的多層物体の傾きもしくは高さを多層構造に影響さ
れずに正確に測定することが可能となり、半導体露光装
置に於る焦点合せ及びウエハ面の結像面への合せ込みの
ための傾き制御を正確に実行することが可能となり、
0.8μm以下、特に0.5μm近傍以下の線幅回路パ
ターンの露光に用いられる高NAi線縮小露光装置や、
エキシマレーザ縮小露光装置で発生すると予想される浅
い焦点深度に伴なう、露光焦点マージンの減少に対し、
極めて顕著な効果を発揮する。As described above, according to the present invention, the inclination or height of an optical multilayer object such as a wafer having various multilayer structures in a semiconductor circuit manufacturing process can be accurately measured without being affected by the multilayer structure. It is possible to accurately execute the focus control in the semiconductor exposure apparatus and the tilt control for adjusting the wafer surface to the image forming surface,
A high NAi line reduction exposure apparatus used for exposure of a line width circuit pattern of 0.8 μm or less, especially around 0.5 μm or less,
In response to the decrease in exposure focus margin due to the shallow depth of focus expected to occur in excimer laser reduction exposure equipment,
It has a very remarkable effect.
【図1】各々本発明の一実施例を示す装置構成図。FIG. 1 is an apparatus configuration diagram showing one embodiment of the present invention.
【図2】各々本発明の一実施例を示す装置構成図。FIGS. 2A and 2B are device configuration diagrams each showing an embodiment of the present invention.
【図3】本発明の原理説明のための図。FIG. 3 is a diagram for explaining the principle of the present invention.
【図4】従来の課題を説明する図。FIG. 4 is a diagram illustrating a conventional problem.
【図5】本発明の原理と効果を説明する特性図。FIG. 5 is a characteristic diagram illustrating the principle and effect of the present invention.
【図6】本発明の原理と効果を説明する特性図。FIG. 6 is a characteristic diagram illustrating the principle and effect of the present invention.
【図7】本発明の原理と効果を説明する特性図。FIG. 7 is a characteristic diagram illustrating the principle and effect of the present invention.
【図8】従来技術を説明するための図。FIG. 8 is a diagram for explaining a conventional technique.
【図9】従来技術を説明するための図。FIG. 9 is a diagram for explaining a conventional technique.
【図10】本発明の他の一実施例を示す構成図。FIG. 10 is a configuration diagram showing another embodiment of the present invention.
【図11】図10の実施例を説明するための図。FIG. 11 is a view for explaining the embodiment in FIG. 10;
【図12】図10の実施例を説明するための図。FIG. 12 is a view for explaining the embodiment in FIG. 10;
【図13】更に本発明の他の一実施例図を示す構成図。FIG. 13 is a configuration diagram showing still another embodiment of the present invention.
【図14】図13に示す実施例を説明するための図。FIG. 14 is a view for explaining the embodiment shown in FIG. 13;
【図15】更に本発明の他の一実施例を示す構成図。FIG. 15 is a configuration diagram showing still another embodiment of the present invention.
【図16】図14に示す実施例を説明するための図。FIG. 16 is a view for explaining the embodiment shown in FIG. 14;
【図17】図14に示す実施例を説明するための図であ
る。FIG. 17 is a view for explaining the embodiment shown in FIG. 14;
1…光源、 11…コリメートレンズ、 1
1′…集光レンズ、20…集光レンズ、 21,22
…レンズ、13,14,210…ミラー、 16,
19…ハーフミラー、3…一次元センサ、 3′,
3′′…光位置検出器、 4…ウエハ、5,5′…
処理回路、 7…ステージ、 8…縮小露光レ
ンズ、81…照明、 9…リチクル。1: light source, 11: collimating lens, 1
1 ': condenser lens, 20: condenser lens, 21, 22
... Lens, 13, 14, 210 ... Mirror, 16,
19: half mirror, 3: one-dimensional sensor, 3 ',
3 "... Optical position detector, 4 ... Wafer, 5, 5 '...
Processing circuit, 7: stage, 8: reduction exposure lens, 81: illumination, 9: reticle.
フロントページの続き (51)Int.Cl.6 識別記号 FI G03F 9/02 G03F 9/02 H01L 21/66 H01L 21/66 P Continued on the front page (51) Int.Cl. 6 Identification code FI G03F 9/02 G03F 9/02 H01L 21/66 H01L 21/66 P
Claims (13)
5度以上の入射角度で光を照射し、該光が照射された個
所の前記試料表面の像を検出器上に結像させ、該結像さ
せた前記試料表面の像を前記検出器で検出し、該検出し
た前記試料表面の像に基づいて前記試料表面の高さを検
出することを特徴とする試料表面の高さ検出方法。1. The method according to claim 1, wherein the surface of the sample is 8
Light is irradiated at an incident angle of 5 degrees or more, an image of the sample surface at the position where the light is irradiated is formed on a detector, and the formed image of the sample surface is detected by the detector. Detecting the height of the sample surface based on the detected image of the sample surface.
5度以上の入射角度で光を照射し、該照射による前記表
面からの反射光を検出器上に集光させ、該集光させた反
射光を前記検出器で検出し、該検出した反射光に基づい
て前記試料表面の高さを検出することを特徴とする試料
表面の高さ検出方法。2. The surface of the sample has a height of 8
Irradiating light at an incident angle of 5 degrees or more, collecting reflected light from the surface due to the irradiation on a detector, detecting the collected reflected light with the detector, and detecting the detected reflected light Detecting the height of the sample surface based on the following formula:
あることを特徴とする請求項1または2に記載の試料表
面の高さ検出方法。3. The method according to claim 1, wherein the light applied to the surface of the sample is a laser beam.
線方向に対して82度以上の入射角度で照射し、該光が
照射された個所の前記試料表面の像を検出器上に結像さ
せ、該結像させた前記試料表面の像を前記検出器で検出
し、該検出した前記試料表面の像に基づいて前記試料表
面の高さを検出することを特徴とする試料表面の高さ検
出方法。4. A sample surface is irradiated with S-polarized light at an incident angle of not less than 82 degrees with respect to a normal direction of the surface, and an image of the sample surface at a position where the light is irradiated is detected by a detector. A sample, wherein the image of the sample surface formed on the sample is detected by the detector, and the height of the sample surface is detected based on the detected image of the sample surface. Surface height detection method.
2度以上の入射角度でS偏光させた光を照射し、該照射
による前記表面からの反射光を検出器上に集光させ、該
集光させた反射光を前記検出器で検出し、該検出した反
射光に基づいて前記試料表面の高さを検出することを特
徴とする試料表面の高さ検出方法。5. The surface of the sample has a height of 8 with respect to the normal direction of the surface.
Irradiating S-polarized light at an incident angle of 2 degrees or more, collecting reflected light from the surface due to the irradiation on a detector, detecting the collected reflected light with the detector, A method for detecting the height of the sample surface, comprising detecting the height of the sample surface based on the detected reflected light.
前記光に対して透明な材料で構成されていることを特徴
とする請求項1、2、4または5の何れかに記載の試料
表面の高さ検出方法。6. A place on the sample surface where the light is irradiated,
The method for detecting the height of a sample surface according to any one of claims 1, 2, 4, and 5, wherein the method is made of a material transparent to the light.
載置した試料の表面に該表面の法線方向に対して85度
以上の入射角度で光を照射する照射手段と、該照射手段
により光が照射された個所の前記試料表面の像を検出す
る検出手段と、該検出手段で検出した前記像の信号に基
づいて前記試料表面の高さを算出する表面高さ算出手段
とを備えたことを特徴とする試料表面の高さ検出装置。7. A mounting means for mounting a sample, and an irradiating means for irradiating a surface of the sample mounted on the mounting means with light at an incident angle of 85 degrees or more with respect to a normal direction of the surface. Detecting means for detecting an image of the sample surface at a position irradiated with light by the irradiating means; and calculating a surface height based on a signal of the image detected by the detecting means. Means for detecting the height of the sample surface.
載置した試料の表面に該表面の法線方向に対して85度
以上の入射角度で光を照射する照射手段と、該照射手段
により前記試料の表面に照射された光の反射光を集光す
る集光手段と、該集光手段で集光された前記反射光を検
出する検出手段と、該検出手段で検出した前記反射光の
信号に基づいて前記試料表面の高さを算出する表面高さ
算出手段とを備えたことを特徴とする試料表面の高さ検
出装置。8. A mounting means for mounting a sample, and irradiating means for irradiating a surface of the sample mounted on the mounting means with light at an incident angle of 85 degrees or more with respect to a normal direction of the surface. A light collecting means for collecting reflected light of light illuminated on the surface of the sample by the irradiation means; a detecting means for detecting the reflected light collected by the light collecting means; and a detecting means for detecting the reflected light. Surface height calculating means for calculating the height of the sample surface based on the signal of the reflected light.
試料表面に前記レーザ光源部から発射したレーザ光を照
射することを特徴とする請求項7または8に記載の試料
表面の高さ検出装置。9. The height of the sample surface according to claim 7, wherein the irradiating means has a laser light source unit, and irradiates the sample surface with laser light emitted from the laser light source unit. Detection device.
に載置した試料の表面に該表面の法線方向に対して82
度以上の入射角度でS偏光させた光を照射する照射手段
と、該照射手段により光が照射された個所の前記試料表
面の像を検出する検出手段と、該検出手段で検出した前
記像の信号に基づいて前記試料表面の高さを算出する表
面高さ算出手段とを備えたことを特徴とする試料表面の
高さ検出装置。10. A mounting means for mounting a sample, and a surface of the sample mounted on the mounting means, the surface of which is 82 mm normal to the surface.
Irradiating means for irradiating S-polarized light at an incident angle of not less than degrees, a detecting means for detecting an image of the sample surface at a position irradiated with light by the irradiating means, and an image of the image detected by the detecting means. And a surface height calculating means for calculating the height of the sample surface based on the signal.
に載置した試料の表面に該表面の法線方向に対して82
度以上の入射角度でS偏向させた光を照射する照射手段
と、該照射手段により前記試料の表面に照射された光の
反射光を集光する集光手段と、該集光手段で集光された
前記反射光を検出する検出手段と、該検出手段で検出し
た前記反射光の信号に基づいて前記試料表面の高さを算
出する表面高さ算出手段とを備えたことを特徴とする試
料表面の高さ検出装置。11. A mounting means for mounting a sample, and a surface of the sample mounted on the mounting means, the surface of which is 82 mm normal to the surface.
Irradiating means for irradiating S-deflected light at an incident angle of not less than degree, condensing means for condensing reflected light of the light irradiated on the surface of the sample by the irradiating means, and condensing light by the condensing means A detecting means for detecting the detected reflected light, and a surface height calculating means for calculating a height of the sample surface based on a signal of the reflected light detected by the detecting means. Surface height detector.
を有することを特徴とする請求項7、8、10または1
1の何れかに記載の試料表面の高さ検出装置。12. The apparatus according to claim 7, wherein said detecting means has an image detector for detecting an image.
2. The apparatus for detecting the height of a sample surface according to any one of 1 to 1 above.
とを特徴とする請求項12に記載の試料表面の高さ検出
装置。13. The apparatus according to claim 12, wherein said image detector is a one-dimensional sensor.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10150922A JP3003671B2 (en) | 1998-06-01 | 1998-06-01 | Method and apparatus for detecting height of sample surface |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10150922A JP3003671B2 (en) | 1998-06-01 | 1998-06-01 | Method and apparatus for detecting height of sample surface |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8097987A Division JP2861927B2 (en) | 1996-04-19 | 1996-04-19 | Method and apparatus for detecting inclination or height of optical multilayer object |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH116714A true JPH116714A (en) | 1999-01-12 |
JP3003671B2 JP3003671B2 (en) | 2000-01-31 |
Family
ID=15507348
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JP10150922A Expired - Fee Related JP3003671B2 (en) | 1998-06-01 | 1998-06-01 | Method and apparatus for detecting height of sample surface |
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JP (1) | JP3003671B2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2010271603A (en) * | 2009-05-25 | 2010-12-02 | Nikon Corp | Apparatus for detecting surface position, apparatus for forming pattern, method for detecting surface position, method for forming pattern, and device manufacturing method |
JP2017021382A (en) * | 2005-07-08 | 2017-01-26 | 株式会社ニコン | Position detection apparatus, exposure apparatus, and exposure method |
-
1998
- 1998-06-01 JP JP10150922A patent/JP3003671B2/en not_active Expired - Fee Related
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017021382A (en) * | 2005-07-08 | 2017-01-26 | 株式会社ニコン | Position detection apparatus, exposure apparatus, and exposure method |
JP2018081314A (en) * | 2005-07-08 | 2018-05-24 | 株式会社ニコン | Position detection apparatus, exposure apparatus, and exposure method |
JP2010271603A (en) * | 2009-05-25 | 2010-12-02 | Nikon Corp | Apparatus for detecting surface position, apparatus for forming pattern, method for detecting surface position, method for forming pattern, and device manufacturing method |
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JP3003671B2 (en) | 2000-01-31 |
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