JP2009038264A - Exposure apparatus and device manufacturing method - Google Patents

Abstract

【Task】
An exposure apparatus for improving shot alignment accuracy is provided.
[Solution]
An exposure apparatus that exposes a substrate 2 through a mask 1, each of which has a plurality of shot areas having overlapping areas through the mask 1 having measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7, and mp8. The exposure is performed, the amount of positional deviation between the measurement mark pairs formed in each overlapping area by this exposure is measured, and the plurality of shots are calculated from the positional deviation data obtained for each overlapping area using the least square method. (i, j), (i, j + 1), (i + 1, j), the respective arrangement errors are obtained.
[Selection] Figure 3

Description

  The present invention relates to an exposure apparatus and a device manufacturing method for exposing a substrate through a mask.

When manufacturing a liquid crystal panel, the color filter substrate and the TFT substrate are bonded together. However, if the shots are not aligned on the substrate, the light from the light guide plate does not stick correctly. Cannot pass through.
Therefore, at the time of adjustment work, a part of an adjacent shot adjacent to a predetermined shot is superimposed and exposed to measure measurement marks that have been exposed, and the operator has empirically adjusted the arrangement from the measurement values of the measurement marks. .
Further, when measuring the position error (linearity / rotation) of the substrate stage, an operator can empirically determine the substrate from the measurement value of the measurement mark by measuring a plurality of measurement marks using a super dimension measuring instrument. The stage position error has been adjusted.
Further, for example, Japanese Patent Publication No. Sho 63-38697 (Patent Document 1) proposes a distortion measuring method using superimposing a main scale mark and a sub-scale mark.
Japanese Examined Patent Publication No. 63-38697

In the above-described conventional example, since the relative alignment adjustment is performed with an adjacent shot adjacent to a predetermined shot, the lattice depends on the adjacent shot.
For this reason, as shown in FIG. 7, it is difficult to adjust the arrangement of the first shot 50 and the final shot 51, and the arrangement cannot be an ideal lattice.
Furthermore, since the relative alignment with the adjacent shots is adjusted, if an orientation error or expansion / contraction error occurs in the first shot due to distortion of the mirror optical system, the entire shot is first displayed as shown in FIG. Depending on the error of the shot 50, the arrangement cannot be an ideal lattice.
Furthermore, when using an ultra dimension measuring instrument, if an irregular position error occurs in the substrate stage of the ultra dimension measuring instrument, it is difficult to adjust the position error of the substrate stage of the exposure apparatus. is there.
Accordingly, an object of the present invention is to improve shot arrangement accuracy.

  An exposure apparatus of the present invention for solving the above problems is an exposure apparatus that exposes a substrate through a mask, and exposes each of a plurality of shot areas having overlapping areas through a mask having measurement marks, The amount of misalignment between the measurement mark pairs formed in each overlapping region by exposure is measured, and the alignment error of each of the plurality of shots is calculated from the misalignment data obtained for each overlapping region using the least square method. It is characterized by seeking.

  Furthermore, the exposure apparatus of the present invention is an exposure apparatus that has a substrate stage that moves while holding a substrate, and that exposes the substrate through a mask, and has a plurality of overlapping regions through a mask having measurement marks. Each shot area is exposed, the amount of positional deviation between the measurement mark pairs formed in each superimposed area by the exposure is measured, and the least square method is used from the positional deviation data obtained for each superimposed area. And determining a positioning error of the substrate stage.

  According to the present invention, for example, shot arrangement accuracy can be improved.

First, a scanning exposure apparatus according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a schematic view of an exposure apparatus according to an embodiment of the present invention.
An exposure apparatus according to an embodiment of the present invention includes a mask 1, a substrate 2, an illumination optical system and condenser lens 21, an observation optical system 22, a mask stage 23, a body structure 24 body, a mirror optical system 25, and an X direction magnification control system 26. And a substrate stage 28.
Further, a mask Y-axis control laser interferometer 29, a plate Y-axis control laser interferometer 30, a mask Y-axis drive motor 31, a plate Y-axis drive motor 32, a control circuit 34, an arithmetic device 35, a storage device, an image processing device, and a substrate A transfer robot 40 is included.
The exposure light emitted from the illumination optical system 21 is condensed on the upper surface of the mask 1 via the condenser lens 21, and the condensed exposure light is condensed on the upper surface of the substrate 2 via the projection mirror optical system 25. The
The mask 1 is sucked and held on a mask stage 23, and the substrate 2 is sucked and held on a substrate stage 28 that can move in the X and Y directions.
The circuit pattern drawn on the mask 1 is exposed to the substrate 2 by synchronously scanning the mask stage 23 and the substrate stage 28 in the scanning direction.
The circuit pattern is exposed on the entire surface of the substrate 2 by repeatedly performing the exposure process by the synchronous scan control while moving the substrate stage 28 stepwise.
The observation optical system 22 images the marks on the mask 1 and the substrate 2, and the captured image is subjected to measurement processing by the image processing device 35.
The control circuit 34 drives and controls the mask stage 23 and the substrate stage 28 by controlling the motor 31 and the motor 32 in accordance with the correction amount calculated by the arithmetic unit 35.

Next, Embodiment 1 of the present invention will be described with reference to FIG.
The exposure apparatus according to the first embodiment exposes a plurality of shot areas having overlapping areas through a mask 1 having measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7, and mp8.
By this exposure, the amount of positional deviation between the measurement mark pairs formed in each overlapping region is measured.
Further, the arrangement error of each of the plurality of shots (i, j), (i, j + 1), (i + 1, j) is obtained from the positional deviation data obtained with respect to each overlapping region using the least square method. .
FIG. 2 is a layout diagram of the mask 1 according to the first embodiment, and a mask through portion for measuring the measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7, mp8 and the measurement marks on the substrate 2. A.
Using the measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7, mp8 and the mask threading portion A, the substrate stage 28 is placed at an exposure position set so that a predetermined shot and an adjacent shot adjacent to each other overlap each other. Move and expose on the substrate 2.

FIG. 3 is a diagram when the substrate 2 is exposed.
Assume that an adjacent shot (i, j + 1) adjacent to the predetermined shot (i, j) in the X direction and an adjacent shot (i + 1, j) adjacent to the Y direction.
A shot that is adjacent to the adjacent shot (i, j + 1) in the Y direction is defined as (i + 1, j + 1).
Next, the observation optical system 22 is moved to a preset mask insertion portion A, and the substrate stage 28 is moved to a preset measurement position, so that measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7 and mp8 are measured with high accuracy.
Here, as shown in FIG. 3, the measurement marks that overlap between the shot (i, j) and the shot (i, j + 1) are p1 and p2.
The measurement marks that overlap between the shot (i, j) and the shot (i + 1, j) are p3 and p4.
Furthermore, the measurement values p1, p2, p3, and p4 measured using the observation optical system 22 are measured values in the X and Y directions, respectively (x1, y1), (x2, y2), (x3, y3). , (X4, y4).
At this time, posture errors at ideal positions of the shots (i, j), (i + 1, j), and (i, j + 1) are dθ1, dθ2, and dθ3, respectively.
The expansion / contraction errors in the X direction and the Y direction are (dx1, dy1), (dx2, dy2), and (dx3, dy3), respectively.
The constant errors of each shot caused by the attitude error of the mirror optical system 25 and the measurement error of the observation optical system 22 are respectively expressed as Δx (i, j), Δy (i, j), Δx (i, j + 1), Δ
Let y (i, j + 1), Δx (i + 1, j), Δy (i + 1, j).
Under the above conditions, the relationships of equations (1) to (8) are established between the shots.

Formulas (1), (3), (5), and (7) are superimposed in the X direction, and formulas (2), (4), (6), and (8) are superimposed in the Y direction. It is established every time.
For this reason, if M is the number of measurement points superimposed in the X direction and N is the number of measurement points superimposed in the Y direction, 2M (N−1) + 2N (M−1) simultaneous equations are established.
Since the solution cannot be obtained unless the average value of the posture error and the expansion / contraction error of all shots is set to be constant, the sum of each shot is set to zero.

ここで、Ｎ_ｘはショット数を表す。
Ｘ方向、Ｙ方向の伸縮誤差を、それぞれ(ｄｘ１，ｄｙ１)， (ｄｘ２，ｄｙ２)， (ｄｘ３，ｄｙ３)とする。
ショット(ｉ，ｊ)，(ｉ＋１，ｊ)，(ｉ，ｊ＋１)の理想位置における姿勢誤差を、それぞれｄθ１，ｄθ２，ｄθ３とする。

Here, N _x represents the number of shots.
The expansion / contraction errors in the X direction and the Y direction are (dx1, dy1), (dx2, dy2), and (dx3, dy3), respectively.
Posture errors at ideal positions of shots (i, j), (i + 1, j), and (i, j + 1) are dθ1, dθ2, and dθ3, respectively.

By using mathematical means based on the least square method for the simultaneous equations configured as described above, an optimum correction amount that minimizes the error for all shots is obtained.
The calculated correction amount is stored in a magnetic disk of the storage device 35, and thereafter, the alignment between shots can be corrected by reflecting the correction amount at the time of exposure.
Further, the first embodiment is characterized in that the N-th array correction amount does not depend on the (N-1) th array correction amount.
If an irregular measurement error that occurs due to factors such as the attitude error of the mirror optical system 25 occurs, the arrangement adjustment is performed again according to the procedure of the first embodiment.
As a result of the arrangement adjustment, the calculated arrangement correction amount of each shot does not depend on the arrangement correction amount corrected as described above. Therefore, the arrangement can be corrected by adding to the arrangement correction amount corrected as described above.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
The exposure apparatus according to the second embodiment exposes each of a plurality of shot areas having an overlapping area through a mask having measurement marks mp1, mp2, mp3, mp4, mp5, mp6, mp7, and mp8.
By this exposure, the amount of positional deviation between the measurement mark pairs formed in each overlapping region is measured.
A positioning error of the substrate stage 28 shown in FIG. 1 is obtained from the positional deviation data obtained with respect to each overlapping region using a least square method.
FIG. 4 is a diagram of a mask layout used in the second embodiment. Masking is performed using a member that limits an exposure region (not shown) so that only the inside of the masking line 41 is transferred, and is shown in FIG. The entire surface of the substrate 2 to be exposed is exposed.
Using the data obtained using the exposure apparatus of the second embodiment, the optimum correction that minimizes the error for all shots using the exposure apparatus of the first embodiment from the attitude error at each measurement point. Find the amount.
By doing so, the position error of the substrate stage 28 can be corrected as in the first embodiment.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS.
FIG. 5 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. 6 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.

It is the schematic of the exposure apparatus of the Example of this invention. It is a mask layout figure used with the exposure apparatus of Example 1 of this invention. It is an enlarged view of the exposure state of the glass substrate in the exposure apparatus of Example 1 of this invention. It is a layout diagram of a mask used in the exposure apparatus of Example 2 of the present invention. It is a flowchart for demonstrating manufacture of the device using the exposure apparatus of a present Example. 6 is a detailed flowchart of the wafer process in Step 4 of the flowchart shown in FIG. 5. It is explanatory drawing of a prior art example. It is explanatory drawing of another prior art example.

Explanation of symbols

1: mask, 2: substrate, 21: illumination optical system,
22: Observation optical system, 23: Mask stage, 24: Main body structure,
25: mirror projection optical system, 26: X direction magnification control system, 28: substrate stage,
29: Mask Y-axis control laser interference, 30; Plate Y-axis control laser interferometer,
31: Mask Y-axis drive motor, 32: Plate Y-axis drive motor,
34: control circuit, 35: arithmetic device, storage device, and image processing device,
40: substrate transfer robot,
P1, P2, P3, P4: marks overlapped by superimposing exposure, A: mask through portion

Claims (3)

An exposure apparatus that exposes a substrate through a mask,
Exposing each of a plurality of shot areas having an overlapping area through a mask having a measurement mark,
Measure the amount of misalignment between the measurement mark pair formed in each overlapping region by the exposure,
From the positional deviation data obtained for each superimposed region, find the alignment error of each of the plurality of shots using a least square method,
An exposure apparatus characterized by that. An exposure apparatus having a substrate stage that holds and moves a substrate, and exposes the substrate through a mask,
Exposing each of a plurality of shot areas having an overlapping area through a mask having a measurement mark,
Measure the amount of misalignment between the measurement mark pair formed in each overlapping region by the exposure,
From the positional deviation data obtained for each overlapping region, find the positioning error of the substrate stage using a least square method,
An exposure apparatus characterized by that. 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 characterized by comprising:

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