JP2009170559A - Exposure device, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device measuring a movement error of a substrate stage in a short time. <P>SOLUTION: This exposure device includes a stage holding a substrate and moved, and a scope imaging a mark on the substrate held to the stage, and exposes the substrate held to the state to light. The exposure device is characterized by having a processing part causing the scope to sequentially image a plurality of first marks arranged on a measuring substrate on the substrate stage to be moved, thereby calculating the respective positions and rotating amounts of the plurality of first marks by using the scope as a reference, and calculating a movement error of the substrate stage based on the respective calculated positions and rotating amounts of the plurality of first marks, and the respective pre-measured positions and rotating amounts of the plurality of first marks. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exposure apparatus having a substrate stage.

The geometric error in the position of the substrate stage in the exposure apparatus is caused by, for example, the straightness of the plane mirror attached to the substrate stage or the parallelism of the laser optical axis reflected by the plane mirror. Affects the match.
Therefore, conventionally, for example, the geometric error of the stage position has been measured and corrected by the following three methods.
The method of the first conventional example proposed in Japanese Patent No. 3427113 (Patent Document 1) uses a measurement wafer in which a scope observation mark is formed on the entire surface of a wafer as a substrate by another semiconductor exposure apparatus. The observation marks are sequentially measured with a scope.
By this measurement, the geometric error of the position of the substrate stage is measured and corrected.
In the second conventional method proposed in Japanese Patent Laid-Open No. 2000-299278 (Patent Document 2), a geometric error in the position of the substrate stage is detected from an overlay mark formed in a partial region of an adjacent shot. Correct the measurement.
The method of the third conventional example proposed in Japanese Patent Laid-Open No. 2005-64268 (Patent Document 3) uses the wafer coated with the latent image resist, so that the development process of the second conventional method is performed. This is an omitted method.
Japanese Patent No. 3427113 JP 2000-299278 A JP 2005-64268 A

However, in the method of the first conventional example of Japanese Patent No. 3427113 (Patent Document 1), since the position error of the substrate stage when transferring the measurement mark is unknown, the position error of the mark is large.
The method of the second conventional example of Japanese Patent Laid-Open No. 2000-299278 (Patent Document 2) has an advantage that the influence of the position error of the substrate stage can be removed.
However, since steps such as resist coating, exposure, development, and overlay mark measurement on the entire wafer surface are required, it is difficult to automatically measure the geometric error of the position of the substrate stage.
Therefore, there is a need for a method for measuring the geometric error of the stage position with high accuracy without requiring the steps of resist coating, exposure, development, and overlay mark measurement on the entire wafer surface.
The method of the third conventional example of Japanese Patent Laying-Open No. 2005-64268 (Patent Document 3) does not require a development process, and thus automatic measurement is possible. However, since the exposure process cannot be omitted, the inspection time becomes long. It was.
Accordingly, an object of the present invention is to measure the movement error of the substrate stage in a short time.

  An exposure apparatus according to the present invention for solving the above-described problems includes a substrate stage that is moved while holding a substrate, and a scope that images a mark on the substrate held by the substrate stage, and the substrate stage An exposure apparatus that exposes a substrate held on the substrate stage, wherein the scope sequentially images a plurality of first marks arranged on a measurement substrate on the moved substrate stage, and the scope is used as a reference. The position and rotation amount of each of the plurality of first marks are calculated, the calculated position and rotation amount of each of the plurality of first marks, and the position and rotation amount of each of the plurality of first marks measured in advance, And a processing unit for calculating a movement error of the substrate stage.

  According to the present invention, for example, the movement error of the substrate stage can be measured in a short time.

Hereinafter, an exposure apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.
In the process of manufacturing a device such as a semiconductor element, the wafer 103 which is a substrate is exposed using the exposure apparatus of this embodiment shown in FIG.
That is, a pattern of a circuit or the like drawn on a reticle (mask) 101 that is an original plate illuminated by an illumination optical system (not shown) is projected and transferred onto a wafer 103 that is a substrate via a projection optical system 102.
A wafer stage 104 as a substrate stage is moved while holding a wafer 103 as a substrate.
In the measurement method of the geometric error of the substrate stage in the exposure apparatus of the present embodiment, measurement wafers 201 and 301 which are measurement substrates shown in FIGS.
In the measurement wafers 201 and 301, scope observation marks 203 and 303, which are first marks, are arranged on the entire surface, and the positions of the scope observation marks 203 and 303 are measured in advance, and the wafer stage 104 which is a substrate stage. Placed on.
Wafer stage 104 incorporates an actuator and is positioned with high accuracy based on the output of laser interferometer 105 that measures the position of wafer stage 104 with high accuracy.
The wafer 103 that has been subjected to the exposure process is subjected to various chemical processes and physical processes, and then loaded into the exposure apparatus for re-exposure.
The position of the scope observation mark, which is the first mark provided on the measurement wafers 201, 301, or the inspection mark to be superimposed, which is the second mark, is observed with the scope 106, which is a measuring instrument including a microscope. . The holding unit 109 holds the scope 106.
The scope 106 is means for imaging the marks on the measurement wafers 201 and 301 that are substrates held by the wafer stage 104 that is a substrate stage.

The processing unit includes an arithmetic unit 107 and a controller 108.
The processing unit uses the scope observation marks 203, 205, and 207, which are a plurality of first marks arranged on the measurement wafer 201 that is the measurement substrate on the wafer stage 104 that is the substrate stage to be moved, in the scope 106. Take images sequentially.
Thereby, the processing unit calculates the position and the rotation amount of each of the plurality of first marks 203, 205, and 207 with the scope 106 as a reference.
Further, the processing unit calculates the position and rotation amount of each of the plurality of first marks 203, 205, and 207 calculated and the position and rotation amount of each of the plurality of first marks 203, 205, and 207 measured in advance. Based on this, a movement error of the wafer stage 104 is calculated.
The computing unit 107 calculates a linear relational expression parameter (coefficient) that approximates the amount of positional deviation based on the measurement by the scope 106.
This misregistration amount is a misregistration amount of a shot or mark that is an exposed area on the wafer 103 due to various processes described above and wafer chucking on the wafer stage 104 and the like.
This misregistration amount refers to the linear component of the misregistration amount such as translation, magnification and rotation of the entire exposed region group and translation, magnification and rotation in the exposed region.
The computing unit 107 calculates the target position of the wafer stage 104, and the controller 108 determines the position of the wafer stage 104 based on the parameter calculated by the computing unit 107 or the target position information for exposure of the exposure area. Control.
The controller 108 further controls aberrations such as the projection magnification and distortion of the projection optical system 102 based on the information indicating the amount of positional deviation in the exposure area.
In that case, the projection optical system 102 incorporates an aberration adjusting means including an optical element that can be moved or deformed for aberration adjustment, and an actuator for moving or deforming the optical element. It operates according to information from the device 108.
In the semiconductor exposure apparatus having the above-described configuration, the mounting accuracy of each component is strictly controlled, but the mounting position accuracy is limited to 10 μm and the angle is limited to 10 ppm.
For this reason, an Abbe error occurs in this state of attachment accuracy, and geometric errors such as a stage lattice error, an arrangement error, and a stepping error at the position of the wafer stage 104 occur.

In the measurement method of the geometric error of the first substrate stage in the exposure apparatus of the present embodiment, the measurement wafer 201 which is the measurement substrate shown in FIG. 2 is used.
In this geometric error measurement method of the first substrate stage, the scope observation mark 203 as each first mark is observed with the scope 106 while moving the wafer stage 104 as the substrate stage.
Next, an image of the scope observation mark 203 that is the first observed mark is analyzed.
Next, the position and rotation amount of the scope observation mark 203 which is the first mark on the plane with the scope 106 as a reference are measured.
Next, from the difference between the measured position and rotation amount of the scope observation mark 203 as the first mark and the previously measured position of the scope observation mark 203 as the first mark, the wafer stage 104 A geometric error is calculated by the calculator 107.

FIG. 3 is an enlarged view of a part of the measurement wafer 201, and the position and rotation amount of an arbitrary adjacent overlapping shot 202 are accurately measured.
Therefore, the scope observation mark 203 as the first mark is also transferred equally to each shot 202 whose position and rotation amount are accurately measured.
As shown in FIG. 4, the scope observation mark 205 at the ideal position, which is the first mark, is arranged on the adjacent superposed shot 204 at the ideal position, and is a plane having the shot center as the origin. It is at the position of (x, y) in the coordinate system O.
The scope observation mark 207 at the actual position, which is the first mark, is arranged on the adjacent superposed shot 206 at the actual position.
In the shot 204 and the shot 206, the positional deviation dx, dy and the rotation amount dθ of the shot 206 are accurately measured.
For this reason, the positional deviations бx and бy and the rotation amount бθ of the scope observation mark 205 at the ideal position and the scope observation mark 207 at the actual position are obtained by Expressions (1), (2), and (3). be able to.

次に、この計測用ウェハ２０１をウェハステージ１０４に搭載する。
さらに、各々の第１のマークであるスコープ観察用マーク２０５，２０７が、スコープ１０６が計測できる位置に来るよう、ウェハステージ１０４を移動して、スコープ観察用マーク２０５，２０７の位置を計測する。
このときの計測値がex，ey，eθ，であったとすると、真のウェハステージ１０４の位置誤差ex_o，ey_o，eθ_o，は数式（４）（５）（６）で求めることができる。

Next, the measurement wafer 201 is mounted on the wafer stage 104.
Further, the position of the scope observation marks 205 and 207 is measured by moving the wafer stage 104 so that the scope observation marks 205 and 207, which are the first marks, come to positions where the scope 106 can measure.
If the measured values at this time are ex, ey, eθ, the true position errors ex _o , ey _o , eθ _o of the wafer stage 104 can be obtained by equations (4), (5), and (6). .

計測用基板である計測用ウェハ２０１は、計測用ウェハ２０１の全面に転写された隣接するショット間であるショット２０２，２０２間で重ね合せられる第２のマーク２０３ａ，２０３ｂを形成する。
各々の第２のマーク２０３ａ，２０３ｂの重ね合せ誤差から計測用基板上である計測用ウェハ２０１上の各々のショット２０２の位置と回転量を算出する。
処理部である演算器１０７と制御器１０８は、部分的に重ね合された重ね合せ検査マークとして計測用基板である計測用ウェハ２０１に配列された複数の第２マーク２０３ａ，２０３ｂをスコープ１０６に順次撮像させる。
複数の第２マーク２０３ａ，２０３ｂそれぞれの重ね合せ誤差を計測することにより、予め計測された複数の第１マークであるスコープ観察用マーク２０５，２０７それぞれの位置および回転量を得る。
本実施例の露光装置は、そのマッチング精度を高精度な状態に維持する必要があり、定期的に基板ステージであるウェハ１０４の位置の幾何学的誤差を自動的に短時間で計測する。
これにより、基板ステージであるウェハ１０４の位置の幾何学的誤差を補正する。

A measurement wafer 201 that is a measurement substrate forms second marks 203 a and 203 b that are overlapped between the shots 202 and 202 that are between adjacent shots transferred to the entire surface of the measurement wafer 201.
The position and rotation amount of each shot 202 on the measurement wafer 201 on the measurement substrate are calculated from the overlay error of the second marks 203a and 203b.
The arithmetic unit 107 and the controller 108 which are processing units use a plurality of second marks 203 a and 203 b arranged on the measurement wafer 201 which is a measurement substrate as a partially overlapped inspection mark on the scope 106. Take images sequentially.
By measuring the overlay error of each of the plurality of second marks 203a and 203b, the position and the rotation amount of each of the scope observation marks 205 and 207, which are the plurality of first marks measured in advance, are obtained.
The exposure apparatus of the present embodiment needs to maintain the matching accuracy in a high accuracy state, and automatically measures the geometric error of the position of the wafer 104, which is the substrate stage, in a short time automatically.
Thereby, the geometric error of the position of the wafer 104 as the substrate stage is corrected.

In the measurement method of the geometric error of the second substrate stage in the exposure apparatus of the present embodiment, a measurement wafer 301 which is a measurement substrate shown in FIG. 5 is used.
FIG. 6 is an enlarged view of a part of the measurement wafer 301. The positions and rotation amounts of arbitrary adjacent overlapping shots 302 and 302 are accurately measured.
Therefore, the scope observation mark 303 as the first mark is also transferred equally to each shot 302 whose position and rotation amount are accurately measured.
In this way, the displacement бx and бy of the position of the scope observation mark 303 can also be obtained by Expressions (1), (2), and (3).
Then, the measurement wafer 301 shown in FIG. 5 is mounted on the wafer stage 104 in the same manner as the geometric error measurement method of the first substrate stage in FIG.
Next, the position of the scope observation mark 303 is measured by moving the wafer stage 104 so that the scope observation marks 303, which are the first marks, come to the positions measured by the scope 106.
Measured value of this time ex, ey, When a E.theta,, true position error ex _o of the wafer stage 104, ey _o, eθ _o, may be determined by Equation (4) (5) (6) it can.
A measurement wafer 301 that is a measurement substrate forms second marks 303 a and 303 b that are overlapped between adjacent shots 302 and 302 transferred to the entire surface of the measurement wafer 301.
The position and rotation amount of each shot 302 on the measurement wafer 301 on the measurement substrate are calculated from the overlay error of each of the second marks 303a and 303b.
The arithmetic unit 107 and the controller 108 which are processing units provide the scope 106 with a plurality of second marks 303a and 303b arranged on the measurement wafer 301 which is a measurement substrate as a partially overlapped inspection mark. Take images sequentially.
By measuring the overlay error of each of the plurality of second marks 303a and 303b, the position and the rotation amount of each of the scope observation marks 303, which are the plurality of first marks measured in advance, are obtained.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS.
FIG. 7 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, a semiconductor chip manufacturing method will be described as an example.
The method comprises the steps of exposing a wafer using an exposure apparatus and developing the wafer, and specifically comprises the following steps.
In step 1 (circuit design), a semiconductor device circuit is designed.
In step 2 (mask production), a mask is produced based on the designed circuit pattern.
In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon.
Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer using the mask and the wafer by the above exposure apparatus using the lithography technique.
Step 5 (assembly) is referred to as a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and an assembly process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including.
In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test.
Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 8 is a detailed flowchart of the wafer process in Step 4.
In step 11 (oxidation), the surface of the wafer is oxidized.
In step 12 (CVD), an insulating film is formed on the surface of the wafer.
In step 13 (electrode formation), an electrode is formed on the wafer.
In step 14 (ion implantation), ions are implanted into the wafer.
In step 15 (resist process), a photosensitive agent is applied to the wafer.
Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer.
In step 17 (development), the exposed wafer is developed.
In step 18 (etching), portions other than the developed resist image are removed.
In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed.
By repeatedly performing these steps, multiple circuit patterns are formed on the wafer.

1 is an overall configuration diagram of an exposure apparatus according to an embodiment of the present invention. It is explanatory drawing of the wafer for a measurement of the measuring method of the geometric error of the 1st substrate stage in the exposure apparatus of the Example of this invention. It is explanatory drawing of the adjacent overlapping shot of the measuring method of the geometric error of the 1st substrate stage in the exposure apparatus of the Example of this invention. It is explanatory drawing of the position of the mark for scope observation of the measuring method of the geometric error of the 1st substrate stage in the exposure apparatus of the Example of this invention. It is explanatory drawing of the wafer for a measurement of the measuring method of the geometric error of the 2nd substrate stage in the exposure apparatus of the Example of this invention. It is explanatory drawing of the adjacent overlay shot of the measuring method of the geometric error of the 2nd substrate stage in the exposure apparatus of the Example of this invention. It is a flowchart for demonstrating manufacture of the device using the exposure apparatus of the Example of this invention. It is a detailed flowchart of the wafer process of step 4 of the flowchart shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101: Reticle 102: Projection optical system 103: Wafer 104: Wafer stage 105: Laser interferometer 106: Scope 107: Calculator 108: Controller 201: Measurement wafer 202: Adjacent overlay shot 203: Scope observation mark 204: Adjacent overlay shot 205: Scope observation mark 206: Adjacent overlay shot 207: Scope observation mark 301: Measuring wafer 302: Adjacent overlay shot 303: Scope observation mark

Claims (3)

A substrate stage that is moved while holding the substrate;
A scope for imaging a mark on a substrate held by the substrate stage;
An exposure apparatus for exposing a substrate held on the substrate stage,
By causing the scope to sequentially image a plurality of first marks arranged on the measurement substrate on the substrate stage to be moved, the position and rotation amount of each of the plurality of first marks are calculated with respect to the scope. Processing for calculating a movement error of the substrate stage based on the calculated positions and rotation amounts of the plurality of first marks and the positions and rotation amounts of the plurality of first marks measured in advance. And
An exposure apparatus comprising:   The processing unit causes the scope to sequentially capture a plurality of second marks arranged on the measurement substrate as partially overlapped inspection marks, and to detect a registration error of each of the plurality of second marks. 2. The exposure apparatus according to claim 1, wherein the position and rotation amount of each of the plurality of first marks measured in advance are obtained by measurement. A step of exposing the substrate using the exposure apparatus according to claim 1;
Developing the substrate exposed in the step;
A device manufacturing method comprising:

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