JP3912816B2 - Scanning exposure apparatus and device manufacturing method using the same - Google Patents

Description

ここで、
Ｘｎ ： Ｘｉが計測されてからｎ番目のクロックがカウントされた時のステージ位置座標
Ｘｉ ： ステージ位置計測手段によるｉ番目のステージ位置計測値
Ｖ（ｔ）： ウエハステージの駆動速度、
ａ ： Ｘi が出力された時刻
ｂ ： ｎ回目のクロックが発せられる時刻
である。
【００２０】
式（１）の演算を行うことで、図３（ｂ）に示すようにステージ位置座標を補間して求めることができ、測定間隔間においても自由に発光タイミングを設定できる。
【００２１】
また、ここで示した補間ではステージの加減速プロファイルの補正を行っていないが、駆動中のステージ座標の計測値から加減速プロファイルの補正を行うことにより、更に高精度な制御が可能となる。
【００２２】
ところで、簡易的に加減速プロファイルを意識せず、刻々と更新されるステージ座標の計測値間を線形近似して、以下に示す式（２）のような速度変化情報を用い、次の外部クロック入力時の座標を推測してもよい。
【００２３】
【外２】

ここで、
Ｗ ： クロックの周期
である。
【００２４】
また、本実施形態ではステージの座標を補間する機能をレーザ制御系１０３に持たせているが、ステージ駆動制御系１０１に持たせてもよい。
【００２５】
式（１）により、ウエハステージ１３が加速・定速・減速・停止するまでの間の補間計算を行った例の概念図を図４に示す。
【００２６】
図４において白丸で示されているステージ駆動制御系１０１の測定位置は、実際の間隔よりもまばらに表現している。太い点線は実際のウエハステージの動きであり、細い実線は式（１）によって求められたステージ位置を表している。区間Ａ、区間Ｃは、それぞれステージの加速、減速を行っている時間であり、多項式による曲線補間を行っている。区間Ｂはステージが一定速度で駆動されている区間であり、直線補間が行われている。ステージが一定速度で駆動されている区間Ｂにおいて多項式近似による補間を行うと、駆動プロファイル生成時の量子化誤差が存在する場合や、振動等による影響でステージ駆動制御系１０１の計測値に誤差が生じた場合に、補間しようとする区間においてこれらの誤差が拡大されるので好ましくない。
【００２７】
ところで、エキシマレーザ等のパルスレーザ光源には、発光毎の強度ばらつきが存在するため、いかに正確な露光位置で露光を行ったとしても、パルス光の強度ばらつきにより露光むらが生ずるといった問題がある。そこで、以下にパルスレーザ光源の発光強度ばらつきによる露光むらの補正方法についての説明をする。
【００２８】
図５は、レチクル９に照射されるパルス光（露光光）の強度プロファイルを表した図である。マスキングブレード６をレチクル９との共役位置からわずかにはずすことにより、露光光は台形状の強度プロファイルとなる。ここで、最高強度をｉ０、半影になった部分（斜辺）の幅をｒ、最高強度の部分（上底）までの幅をｗとする。また、任意のＸ座標においてＹ軸に関して積分した値を強度値と定義するならば、図６の説明での直感的な理解を助けるため、ｗ＜Ｘ＜ｒ＋ｗの区間は、図５の網掛け部分のようにプロファイルを変形しても等価として扱える。
【００２９】
図６は、走査露光を行った場合のウエハ１２上の積算露光量を見積もるための概念図である。図６における任意のＸ座標においてＹ軸に関して積分した値を積算露光量と定義する。Ｉｎ−３〜Ｉｎ＋２は、パルスレーザ光源１の各発光時に露光された露光量であり、図５における強度プロファイルそのものに対応する。
【００３０】
ここで、ｎ番目の発光位置をδずらし、座標Ｘｎで露光を行った場合、積算露光量は図７のようになる。すなわち、積算露光量はｉ０δ／ｒだけ、図７に示したようなプロファイルで減少する。図９は、図８に示すように（ｎ−１）番目の露光光における発光強度がΔＩｎ−１だけ大きかった場合に、
【００３１】
【外３】

となるように、発光位置をδだけＸ軸の正方向にずらして発光させた場合のウエハ上の積算露光量を表す図である。予期した値よりも大きな強度で発光がなされた時（図９における区間ａ）、次回の発光位置を後ろにずらす（発光タイミングを遅らせる）ことにより、Ｉｎが積算される位置までは積算露光量は減少し（区間ｂ）、区間ｃにおいて目標積算露光量となる。その後、Ｉｎ−１のプロファイルの右方の裾野部分（半影部分）にさしかかると、積算露光量はさらに減少し（区間ｄ）、Ｉｎを後ろにずらした分の最高強度の部分にさしかかると、再び目標積算露光量に向かって回復する（区間ｅ）。なお、予期した値よりも小さな強度で発光がなされた場合は、式（３）にしたがって、次回の発光位置を前にずらせば（発光タイミングを早めれば）よい。この式（３）に相当する演算を目標位置演算装置２０２は行っており、次回発光位置を決定する。
【００３２】
ここで示した例は、便宜上、１ショットに必要とされる目標積算露光量が２パルス前後で達成できるような説明になっているが、実際には２０〜５０パルス程度の露光光の積算が必要であると考えられるので、ｉ０は目標積算露光量に対して相対的に小さくなり、したがって、積算露光量むらは図９に示した形状よりも更に平坦になる。
【００３３】
次に図２に示した実施形態とは異なり、放電電圧演算装置２０４において次回の目標露光量に基づいて指定放電電圧を演算する方法について説明する。
【００３４】
次回発光用の指定放電電圧は、式（４）に示すように前回の発光履歴の、もしくは式（５）に示すように以前の複数の発光履歴のパルス光強度、指定放電電圧の関係から決定される。
【００３５】
【外４】

ここで、Ｖｉはｉ番目に供給されるパルス光の指定放電電圧、Ｖ０は基準指定放電電圧、Ｅｉ−１は露光量検出器により計測されたｉ−１番目の露光量、Ｔｉ−１はｉ−１番目の目標露光量、Ｐｉはｉ番目までの目標積算露光量である。
【００３６】
本実施形態では、発光強度ばらつきによる露光むらの補正方法として、次回発光位置を変動させる（発光タイミングを制御する）方法を行っているが、式（４）または式（５）で演算されるような指定放電電圧を制御する方法を行ってもよい。また、一方の方法のみで露光むらを十分に補正できない場合等は、両方の方法を併用することも可能である。
【００３７】
また、本実施形態では光源をパルスレーザ光源として説明したが、パルス光を供給する光源であればレーザでなくとも本発明は実現できる。
【００３８】
ステージ駆動制御系１０１では、演算されたステージ現在位置をもとにレチクルステージ１０とウエハステージ１３の逐次目標位置も演算しているが、このステージ位置の逐次目標位置を補間演算した値と、次回発光位置が一致した時に発光をさせるよう構成しても同様の効果が期待できる。
【００３９】
このように、離散的にレチクルステージやウエハステージの所定位置座標、すなわちレチクルやウエハの所定位置座標を測定する走査型露光装置においても、測定値間を補間する手段を有することによって、正確な位置で均一に露光を行うことができる。
【００４０】
（実施形態２）
次に、本発明の走査型露光装置を使用した半導体デバイスの製造方法の実施形態を説明する。
【００４１】
図１０は半導体デバイス（ＩＣやＬＳＩ等の半導体チップ、液晶パネルやＣＣＤ）の製造フローを示す。ステップ１１（回路設計）では半導体デバイスの回路設計を行う。ステップ１２（マスク制作）では設計した回路パターンを形成したマスク（レチクル９）を制作する。一方、ステップ１３（ウエハ製造）ではシリコン等の材料を用いてウエハ（ウエハ１２）を製造する。ステップ１４（ウエハプロセス）は前工程と呼ばれ、上記用意したマスクとウエハとを用いて、リソグラフィー技術によってウエハ上に実際の回路を形成する。次のステップ１５（組み立て）は後工程と呼ばれ、ステップ１４によって作成されたウエハを用いてチップ化する工程であり、アッセンブリ工程（ダイシング、ボンディング）、パッケージング工程（チップ封入）等の工程を含む。ステップ１６（検査）ではステップ１５で作成された半導体デバイスの動作確認テスト、耐久性テスト等の検査を行う。こうした工程を経て半導体デバイスが完成し、これが出荷（ステップ１７）される。
【００４２】
図１１は上記ウエハプロセスの詳細なフローを示す。ステップ２１（酸化）ではウエハ（ウエハ１２）の表面を酸化させる。ステップ２２（ＣＶＤ）ではウエハの表面に絶縁膜を形成する。ステップ２３（電極形成）ではウエハ上に電極を蒸着によって形成する。ステップ２４（イオン打込み）ではウエハにイオンを打ち込む。ステップ２５（レジスト処理）ではウエハにレジスト（感材）を塗布する。ステップ２６（露光）では上記走査型露光装置によってマスク（レチクル１０９）の回路パターンの像でウエハを露光する。ステップ２７（現像）では露光したウエハを現像する。ステップ２８（エッチング）では現像したレジスト以外の部分を削り取る。ステップ２９（レジスト剥離）ではエッチングが済んで不要となったレジストを取り除く。これらステップを繰り返し行うことによりウエハ上に回路パターンが形成される。
【００４３】
本実施形態の製造方法を用いれば、従来は難しかった高集積度の半導体デバイスを製造することが可能になる。
【００４４】
【発明の効果】
以上説明したように、本発明によれば、均一に露光を行うことができる露光装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す走査型露光装置の概略図である。
【図２】レーザ制御系１０３内部の構成を示す図である。
【図３】ステージの加減速プロファイルを示す図である。
【図４】ウエハステージが加速・定速・減速・停止するまでの間のステージ位置の補間計算を行った例の概念図である。
【図５】レチクルに照射される露光光の強度プロファイルを表す図である。
【図６】走査露光を行った場合のウエハ上の積算露光量を見積もるための概念図である。
【図７】発光強度ばらつきがない場合に、ｎ番目の露光光の発光位置をδだけずらした場合の積算露光量を表す図である。
【図８】光源強度ばらつきが起こった場合に、発光位置をδだけＸ軸の正方向にずらして積算露光量の補正を行うことを説明するための図である。
【図９】光源強度ばらつきが起こった場合に、発光位置をδだけＸ軸の正方向にずらして積算露光量の補正を行った後の積算露光量を表す図である。
【図１０】半導体デバイスの製造フローを示す図である。
【図１１】図１０のウエハプロセスを示す図である。
【符号の説明】
１ パルスレーザ光源
２ ビーム整形光学系
３ オプティカルインテグレータ
６ マスキングブレード
７ 結像レンズ
９ レチクル
１０ レチクルステージ
１１ 投影レンズ
１２ ウエハ
１３ ウエハステージ
１０１ ステージ駆動制御系
１０２ 露光量演算器
１０３ レーザ制御系
１０４ 主制御系
２０２ 目標位置演算装置
２０３ 放電電圧演算装置
２０９ 比較器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus used for manufacturing various devices such as an IC, LSI, CCD, liquid crystal panel, and magnetic head.
[0002]
[Prior art]
In recent years, scanning exposure using a so-called slit scanning method that exposes a wide area by scanning a mask and a wafer synchronously with respect to a slit-shaped illumination region in order to respond to the increase in scale and miniaturization of devices. Devices have been used.
[0003]
In order to perform uniform exposure in a scanning exposure apparatus, it is necessary to scan the reticle and wafer at a stable scanning speed. However, since the reticle and wafer scanning speeds can vary due to some disturbance factor, it is important to control the exposure so that even if the scanning speed varies, it is possible to perform uniform exposure.
[0004]
In a conventional scanning exposure apparatus using a pulse light source such as an excimer laser, an apparatus is known that emits a pulse when a reticle and wafer move to a predetermined position to be exposed next time obtained by calculation. At this time, the actual positions of the reticle and wafer are measured by a position measuring instrument such as a highly accurate laser interferometer.
[0005]
[Problems to be solved by the invention]
However, since the output value from the laser interferometer has an error due to a change in the position of the mirror that is fixed to the reticle or wafer to be measured, or a change in the environment such as temperature or pressure, the wafer stage A time for calculating and correcting this error by the control unit of the control system is required. In addition, it takes time to calculate the sequential target value of the drive stage position using the position measurement value corrected for error for wafer stage control. In other words, the exact position of the reticle or wafer requires a sampling time for the position servo of the drive stage, and can only be measured discretely at a measurement interval of about 1 ms to 0.5 ms. Therefore, when light emission is performed by comparing the actual position (measurement value) of the reticle and wafer with the planned position to be exposed next time as in the above-described apparatus, the light emission timing is limited by the measurement interval of the actual position. As a result, the accuracy of the uneven exposure amount is not improved.
[0006]
The present invention has been made in view of the above problems, and an object thereof is to provide an exposure apparatus that can perform exposure accurately.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pulse light source, an illumination optical system for illuminating a reticle with light from the pulse light source, a reticle stage that holds and moves the reticle, and a wafer that holds and moves the wafer. In the scanning exposure apparatus comprising: a wafer stage; a projection optical system for projecting the reticle pattern onto the wafer; and a first control system for controlling the driving of the reticle stage and the wafer stage. Based on a first stage position signal indicating the position of one of the reticle stage and the wafer stage obtained from the control system in the first period, in the second period shorter than the first period. An arithmetic means for generating a second stage position signal indicating the position of any one of the stages, and based on the second stage position signal Te is a scanning exposure apparatus characterized by having a second control system for controlling the emission timing of the pulsed light source.
[0008]
The calculating means may generate the second stage position signal based on the first stage position signal and information on a speed profile of any one of the preset stages.
[0009]
Further, the calculation means may generate the second stage position signal based on a change amount of the first stage position signal.
[0010]
There are various other preferred embodiments of the exposure apparatus of the present invention, which will be described below.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a schematic view showing an embodiment of the present invention, and represents a scanning exposure apparatus used when manufacturing a semiconductor device such as an IC or LSI, a liquid crystal device, an imaging device such as a CCD, or a device such as a magnetic head. ing.
[0012]
In FIG. 1, a light beam from a pulse laser light source 1 that supplies pulsed light such as an excimer laser is shaped into a desired shape by a beam shaping optical system 2 and directed to a light incident surface of an optical integrator 3 such as a fly eye lens. The The fly-eye lens is a group of a plurality of minute lenses, and a plurality of secondary light sources are formed in the vicinity of the light exit surface. The condenser lens 4 Koehler-illuminates the masking blade 6 with a light beam from the secondary light source of the optical integrator 3. A part of the pulsed light divided by the half mirror 5 is directed to the first exposure amount detector 14. The masking blade 6 and the reticle 9 are arranged in a conjugate relationship by the imaging lens 7 and the mirror 8, and the shape and size of the illumination area in the reticle 9 are defined by the shape of the opening of the masking blade 6. A projection lens 11 projects a circuit pattern drawn on the reticle 9 onto the wafer 12 in a reduced scale. The reticle 9 is fixed to the reticle stage 10 and aligned with the wafer 12 fixed on the wafer stage 13 via the projection lens 11. A second exposure amount detector 15 is disposed on the wafer stage 13, and this second exposure amount detector 15 can monitor the exposure amount when passing through the optical system.
[0013]
Reference numeral 101 denotes a stage drive control system for driving and controlling the reticle stage 10 and the wafer stage 13 accurately in synchronism with the same ratio as the magnification of the projection lens 11. The stage drive control system 101 includes a laser interferometer (not shown) that measures the stage position, a calculator (not shown) that corrects and calculates an error in the output value of the laser interferometer, and the like. It outputs discretely to a laser control system 103 described later. This laser interferometer and calculator constitute the position measuring means of the present invention. In the stage drive control system 101, the sequential target positions of the reticle stage 10 and the wafer stage 13 are also calculated based on the calculated stage current position. An exposure amount calculator 102 A / D converts signals from the first exposure amount detector 14 and the second exposure amount detector 15 and sends data to the laser control system 103. The laser control system 103 outputs a trigger signal and a discharge voltage signal to the pulse laser light source 1 according to a desired exposure amount, and controls the laser output and the light emission interval. At this time, in order to obtain a desired exposure amount, if the trigger signal and the discharge voltage signal are corrected based on the detection results of the first exposure amount detector 14 and the second exposure amount detector 15, the desired amount can be more accurately obtained. Can be obtained. The trigger signal and the discharge voltage signal are based on parameters such as an illuminance monitor signal from the exposure amount calculator 102, a stage current position signal from the stage drive control system, and an intensity reference value and history information from the main control system 104. It oscillates. A main control system 104 performs overall control of the stage drive control system 101, the exposure amount calculator 102, and the laser control system 103. An exposure condition such as a desired exposure amount is input to the input device 105 manually or automatically by the apparatus user. The detection results of the first exposure amount detector 14 and the second exposure amount detector 15 can be displayed on the display unit 106.
[0014]
In this embodiment, based on the data of the light emission scheduled position coordinate table, the stage position measurement value, the acceleration / deceleration profile (speed change information) of the stage, etc., the measurement interval of the current stage position output from the stage drive control system 101 The stage position is interpolated to obtain an estimated value. Next, the configuration of the laser control system 103 that should be the most characteristic of the present invention will be described with reference to FIG.
[0015]
The illuminance monitor signal output from the exposure amount calculator 102 is input to the target position calculation device 202 to calculate the next light emission position of the laser light source so that the integrated exposure amount on the wafer is made uniform. In addition, the target intensity value output from the main control system 104 is input to the discharge voltage calculation device 203 to calculate the designated discharge voltage. In the present embodiment, the intensity target value is always constant. The calculation of the next light emission position will be described in detail later.
[0016]
A buffer 204 records the stage position measurement value output from the stage drive control system 101 every time a load signal is input. The load signal is a signal that is output every time the measurement value output from the stage drive control system 101 is updated, and is a logic level signal in the electric circuit. Reference numeral 205 denotes a counter that counts clocks that are input as a reference signal having a constant frequency. The counter 205 is cleared to 0 by a load signal from the stage drive control system 101. The clock cycle is given by a cycle shorter than the stage position measurement interval in the stage drive control system 101. Reference numeral 206 denotes a speed calculator, which is based on the acceleration / deceleration profile as shown in FIG. 3A based on the difference between the previous stage position measurement value received from the stage drive control system 101 and the current stage position measurement value. The scanning speed of the stage at that time is calculated. A multiplier 207 multiplies the output of the counter 205 and the output of the speed calculator 206, and outputs the distance that the stage has traveled since the load signal was output until the present time. Then, the output from the multiplier 207 and the output from the buffer 204 are added by the adder 208 and become actual stage position data during the measurement interval of the stage drive control system 101. The buffer 204, the counter 205, the speed calculator 206, the multiplier 207, and the adder 208 constitute calculation means for obtaining the current position of the substrate using the speed change information of the present invention.
[0017]
The comparator 209 receives the next light emission position output from the target position calculation device 202 and the stage position data output from the adder 209, generates a trigger signal when both values match, and generates a pulse laser. The light source 1 emits light.
[0018]
As described above, in the present embodiment, the stage coordinates in the next clock are estimated based on the output value of the stage drive control system 101 (stage position measurement value for each measurement interval), the clock frequency, and the acceleration / deceleration profile. The stage coordinates to the comparator are updated when an external clock is input. This relationship is shown in Formula (1).
[0019]
[Outside 1]

here,
Xn: stage position coordinate when the nth clock is counted after Xi is measured Xi: i-th stage position measurement value V (t) by the stage position measuring means: wafer stage drive speed,
a: Time when Xi is output b: Time when the n-th clock is generated.
[0020]
By performing the calculation of Expression (1), the stage position coordinates can be interpolated as shown in FIG. 3B, and the light emission timing can be freely set even between measurement intervals.
[0021]
The interpolation shown here does not correct the acceleration / deceleration profile of the stage, but more accurate control is possible by correcting the acceleration / deceleration profile from the measured values of the stage coordinates during driving.
[0022]
By the way, without being conscious of the acceleration / deceleration profile, linear approximation is performed between the measurement values of the stage coordinates that are updated every moment, and using the speed change information as shown in the following equation (2), the next external clock You may guess the coordinates at the time of input.
[0023]
[Outside 2]

here,
W: Clock period.
[0024]
In this embodiment, the laser control system 103 has a function of interpolating the coordinates of the stage, but the stage drive control system 101 may have the function.
[0025]
FIG. 4 shows a conceptual diagram of an example in which interpolation calculation is performed until the wafer stage 13 is accelerated, constant speed, decelerated, and stopped by the equation (1).
[0026]
The measurement positions of the stage drive control system 101 indicated by white circles in FIG. 4 are expressed more sparsely than actual intervals. The thick dotted line is the actual movement of the wafer stage, and the thin solid line represents the stage position obtained by equation (1). Sections A and C are times for accelerating and decelerating the stage, respectively, and performing curve interpolation using a polynomial. A section B is a section where the stage is driven at a constant speed, and linear interpolation is performed. When interpolation by polynomial approximation is performed in the section B where the stage is driven at a constant speed, there is an error in the measurement value of the stage drive control system 101 when there is a quantization error at the time of generating the drive profile or due to the influence of vibration or the like. If this occurs, it is not preferable because these errors are enlarged in the section to be interpolated.
[0027]
By the way, a pulse laser light source such as an excimer laser has a variation in intensity for each light emission. Therefore, even if exposure is performed at an accurate exposure position, there is a problem that uneven exposure occurs due to a variation in the intensity of pulsed light. Therefore, a method for correcting exposure unevenness due to variations in emission intensity of the pulse laser light source will be described below.
[0028]
FIG. 5 is a diagram showing an intensity profile of pulsed light (exposure light) irradiated on the reticle 9. By slightly removing the masking blade 6 from the conjugate position with the reticle 9, the exposure light becomes a trapezoidal intensity profile. Here, it is assumed that the maximum intensity is i0, the width of the half-shadowed portion (the hypotenuse) is r, and the width to the highest intensity portion (upper base) is w. If the value integrated with respect to the Y axis at an arbitrary X coordinate is defined as the intensity value, the section of w <X <r + w is shaded in FIG. 5 in order to help intuitive understanding in the explanation of FIG. Even if the profile is deformed like the part, it can be treated as equivalent.
[0029]
FIG. 6 is a conceptual diagram for estimating the integrated exposure amount on the wafer 12 when scanning exposure is performed. A value integrated with respect to the Y axis at an arbitrary X coordinate in FIG. 6 is defined as an integrated exposure amount. In-3 to In + 2 are exposure amounts exposed at the time of each light emission of the pulse laser light source 1, and correspond to the intensity profile itself in FIG.
[0030]
Here, when the nth light emission position is shifted by δ and exposure is performed at the coordinate Xn, the integrated exposure amount is as shown in FIG. That is, the integrated exposure amount decreases by a profile as shown in FIG. 7 by i0δ / r. FIG. 9 shows a case where the emission intensity of the (n−1) th exposure light is increased by ΔIn−1 as shown in FIG.
[0031]
[Outside 3]

FIG. 6 is a diagram showing the accumulated exposure amount on the wafer when the light emission position is shifted in the positive direction of the X axis by δ. When light is emitted with an intensity greater than the expected value (section a in FIG. 9), the next light emission position is shifted backward (the light emission timing is delayed), so that the accumulated exposure amount becomes the position where In is accumulated. It decreases (section b) and reaches the target integrated exposure amount in section c. After that, when approaching the right skirt part (penumbra part) of the profile of In-1, the integrated exposure amount further decreases (section d), and when approaching the part with the highest intensity by shifting In backward, It recovers again toward the target integrated exposure amount (section e). If light is emitted with an intensity smaller than the expected value, the next light emission position may be shifted forward (according to the light emission timing) according to Equation (3). The target position calculation device 202 performs a calculation corresponding to the equation (3), and determines the next light emission position.
[0032]
In the example shown here, for the sake of convenience, the target integrated exposure amount required for one shot can be achieved in about two pulses, but in reality, the integration of exposure light of about 20 to 50 pulses is performed. Since it is considered necessary, i0 becomes relatively small with respect to the target integrated exposure amount, and therefore, the unevenness of the integrated exposure amount becomes even flatter than the shape shown in FIG.
[0033]
Next, unlike the embodiment shown in FIG. 2, a method for calculating the designated discharge voltage based on the next target exposure amount in the discharge voltage calculation device 204 will be described.
[0034]
The designated discharge voltage for the next light emission is determined from the relationship between the previous light emission history as shown in equation (4) or the relationship between the pulse light intensity of the previous plurality of light emission histories and the designated discharge voltage as shown in equation (5). Is done.
[0035]
[Outside 4]

Here, Vi is the designated discharge voltage of the i-th pulsed light, V0 is the reference designated discharge voltage, Ei-1 is the i-1th exposure amount measured by the exposure amount detector, and Ti-1 is i. The first target exposure amount, Pi is the target integrated exposure amount up to the i-th.
[0036]
In the present embodiment, as a method for correcting exposure unevenness due to variations in light emission intensity, a method of changing the light emission position next time (controlling the light emission timing) is performed, but it is calculated by Expression (4) or Expression (5). A method for controlling the specified discharge voltage may be performed. In addition, when it is not possible to sufficiently correct exposure unevenness by only one method, both methods can be used in combination.
[0037]
In the present embodiment, the light source is described as a pulse laser light source, but the present invention can be realized without using a laser as long as the light source supplies pulse light.
[0038]
In the stage drive control system 101, the sequential target position of the reticle stage 10 and the wafer stage 13 is also calculated based on the calculated stage current position. The value obtained by interpolating the sequential target position of this stage position and the next time The same effect can be expected even if the light is emitted when the light emission positions coincide.
[0039]
As described above, even in the scanning exposure apparatus that discretely measures the predetermined position coordinates of the reticle stage and the wafer stage, that is, the predetermined position coordinates of the reticle and the wafer, it has a means for interpolating between the measured values, thereby providing an accurate position. Can be uniformly exposed.
[0040]
(Embodiment 2)
Next, an embodiment of a semiconductor device manufacturing method using the scanning exposure apparatus of the present invention will be described.
[0041]
FIG. 10 shows a manufacturing flow of a semiconductor device (a semiconductor chip such as an IC or LSI, a liquid crystal panel or a CCD). In step 11 (circuit design), a semiconductor device circuit is designed. In step 12 (mask production), a mask (reticle 9) on which the designed circuit pattern is formed is produced. On the other hand, in step 13 (wafer manufacture), a wafer (wafer 12) is manufactured using a material such as silicon. Step 14 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 15 (assembly) is called a post-process, and is a process for forming a chip using the wafer created in step 14, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). Including. In step 16 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 15 are performed. A semiconductor device is completed through these processes and shipped (step 17).
[0042]
FIG. 11 shows a detailed flow of the wafer process. In step 21 (oxidation), the surface of the wafer (wafer 12) is oxidized. In step 22 (CVD), an insulating film is formed on the surface of the wafer. In step 23 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 24 (ion implantation), ions are implanted into the wafer. In step 25 (resist process), a resist (sensitive material) is applied to the wafer. In step 26 (exposure), the wafer is exposed with the circuit pattern image of the mask (reticle 109) by the scanning exposure apparatus. In step 27 (development), the exposed wafer is developed. In step 28 (etching), portions other than the developed resist are removed. In step 29 (resist stripping), the resist that has become unnecessary after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.
[0043]
By using the manufacturing method of the present embodiment, it becomes possible to manufacture a highly integrated semiconductor device which has been difficult in the past.
[0044]
【The invention's effect】
As described above, according to the present invention, an exposure apparatus capable of performing uniform exposure can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of a scanning exposure apparatus showing an embodiment of the present invention.
FIG. 2 is a diagram showing an internal configuration of a laser control system 103;
FIG. 3 is a diagram showing an acceleration / deceleration profile of a stage.
FIG. 4 is a conceptual diagram of an example in which interpolation calculation of the stage position is performed until the wafer stage is accelerated, constant speed, decelerated, and stopped.
FIG. 5 is a diagram showing an intensity profile of exposure light irradiated on a reticle.
FIG. 6 is a conceptual diagram for estimating an integrated exposure amount on a wafer when scanning exposure is performed.
FIG. 7 is a diagram showing an integrated exposure amount when the emission position of the nth exposure light is shifted by δ when there is no variation in emission intensity.
FIG. 8 is a diagram for explaining correction of an integrated exposure amount by shifting the light emission position by δ in the positive direction of the X axis when light source intensity variation occurs.
FIG. 9 is a diagram showing the integrated exposure amount after correcting the integrated exposure amount by shifting the light emission position by δ in the positive direction of the X axis when the light source intensity variation occurs.
FIG. 10 is a diagram showing a manufacturing flow of a semiconductor device.
FIG. 11 is a diagram showing the wafer process of FIG. 10;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pulse laser light source 2 Beam shaping optical system 3 Optical integrator 6 Masking blade 7 Imaging lens 9 Reticle 10 Reticle stage 11 Projection lens 12 Wafer 13 Wafer stage 101 Stage drive control system 102 Exposure amount calculator 103 Laser control system 104 Main control system 202 Target position calculation device 203 Discharge voltage calculation device 209 Comparator

Claims (11)

A pulse light source; an illumination optical system for illuminating a reticle with light from the pulse light source; a reticle stage for holding and moving the reticle; a wafer stage for holding and moving a wafer; and a pattern of the reticle on the wafer In a scanning exposure apparatus having a projection optical system for projecting on a first control system and a first control system for controlling the driving of the reticle stage and the wafer stage,
A second shorter than the first cycle is obtained based on a first stage position signal obtained from the first control system in a first cycle and indicating the position of either the reticle stage or the wafer stage. Calculating means for generating a second stage position signal indicating the position of any one of the stages at a period of:
A scanning exposure apparatus comprising: a second control system that controls light emission timing of the pulsed light source based on the second stage position signal.   The exposure apparatus according to claim 1, wherein the first control system includes a laser interferometer that measures the position of any one of the stages.   The said calculating means produces | generates a said 2nd stage position signal based on the said 1st stage position signal and the information of the speed profile of one of the said preset stages. The scanning exposure apparatus according to 1 or 2.   The scanning exposure apparatus according to claim 1, wherein the calculation unit generates the second stage position signal based on a change amount of the first stage position signal.   2. The scanning exposure apparatus according to claim 1, wherein exposure is performed even during acceleration / deceleration of any one of the stages.   The second control system obtains a target position of one of the stages corresponding to the light emission timing of the pulsed light source based on an illuminance monitor signal from an exposure amount detector, and the signal of the target position and the second 6. The scanning exposure apparatus according to claim 1, wherein the light emission timing of the pulse light source is controlled based on the stage position signal.   The scanning exposure apparatus according to claim 1, wherein the first stage position signal is a signal of a target position of any one of the stages calculated by the first control system.   The scanning exposure apparatus according to claim 1, wherein the pulsed light source is an excimer laser.   9. The scanning exposure apparatus according to claim 1, further comprising a control unit that controls the intensity of the pulsed light from the pulsed light source based on an exposure amount detected by an exposure amount detector.   The scanning exposure apparatus according to claim 9, wherein the control unit controls a discharge voltage of the pulse light source.   11. A device manufacturing method comprising a step of exposing a wafer using the scanning exposure apparatus according to claim 1.

Images