JP3722330B2 - Exposure apparatus and device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure apparatus and a device manufacturing method used for manufacturing a liquid crystal panel or the like.
[0002]
[Prior art]
Conventionally, when an alignment mark formed on an original plate or substrate is detected by an observation optical system, the original plate or substrate is aligned based on the result, and an image of the original plate is exposed on the substrate via a projection optical system. The observation optical system is moved to the detection position of the alignment mark only by the drive amount based on the command pulse amount to the pulse motor or the like.
[0003]
[Problems to be solved by the invention]
However, in recent years, the size of the reference original plate has gradually increased due to the increase in size of the liquid crystal panel. As a result, the gap between the alignment marks has become wide, and a drive position error due to the accuracy of the mechanism for driving the alignment mark detection camera installed in the observation optical system has become a problem. . That is, the amount of deviation between the designated movement position when the observation optical system detects the alignment mark and the position after the actual movement becomes large, and the alignment mark cannot be detected. Increasingly, alignment is not possible.
[0004]
An object of the present invention is to make it possible to reliably detect an alignment mark on a substrate or an original plate in an exposure apparatus and a device manufacturing method that can use the exposure apparatus, in view of such problems of the prior art.
[0005]
[Means for Solving the Problems]
In order to achieve this object, in the present invention, in order to align the original plate and the substrate, each alignment mark on the original plate and the substrate is detected by moving to each detection position according to the designated movement position. In an exposure apparatus that exposes an image of the original plate on the substrate through the projection optical system by the aligned original plate or substrate having the means, specified by detecting each alignment mark by the detection means The amount of deviation between the movement position and the alignment mark is obtained and stored, and on the basis of this stored data, when the alignment mark is detected next time by the detecting means, the designated movement position is corrected, and this correction value wherein comprising a control means for moving the detecting means, the control means, the detection means actually positioned inverse transform function g (x) that gives the movement for each designated moving position in accordance with Characterized in der Rukoto to obtain the correction value by using a method of obtaining the correction value by substituting the moving position that is the specified function f (x).
[0006]
Further, in the device manufacturing method of the present invention, in order to align the original plate or the substrate, each alignment mark on the original plate is moved by the detection means, and the detection means is moved to the detection position of each alignment mark. In a device manufacturing method for manufacturing a device by detecting by moving according to a position, using an original plate or a substrate aligned based on the detection result, and exposing an image of the original plate on the substrate via a projection optical system, By detecting each alignment mark by the detection means, a deviation amount between the designated movement position and the alignment mark is obtained and stored, and based on the stored data, the alignment mark by the next detection means is stored. In the detection, the designated moving position is corrected, and the detecting means is moved according to the correction value. Furthermore, the correction value is obtained by substituting each designated movement position into a function f (x) obtained by inversely transforming the function g (x) that gives the position where the detection means actually moves for each designated movement position. The correction value is obtained using a method of obtaining.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the present invention , as shown in FIG. 1, an observation optical system 502 is used as the detection means, and the movement position is designated using the position designation means 100 to move the observation optical system. The drive shaft 104 of the system 502 is moved, and the alignment mark 106 drawn on the original plate is imaged via the CCD camera 105 of the observation optical system 502. At the same time, a deviation amount between the designated position and the actually moved position is calculated from the image of the CCD camera 105 using the image processing circuit 101. The displacement amount calculated there is stored in the storage device 102, and a correction amount for moving the drive shaft 104 to an appropriate position is calculated based on the displacement amount stored by the drive shaft correction means 103. Next time, when the drive shaft 104 is moved using the position specifying means 100, the movement position to which the calculated correction amount is added is specified. As a result, the shift amount can be automatically corrected, and the movement position of the observation optical system coincides with the alignment mark drawn on the original plate (hereinafter referred to as a mask).
Hereinafter, embodiments of the present invention will be described in more detail through examples.
[0009]
【Example】
FIG. 5 is a schematic view showing an exposure apparatus according to an embodiment of the present invention. In this figure, 507 is a substrate, 503 is a mask on which a liquid crystal panel pixel pattern to be transferred to the substrate 507 is formed, 504 is equipped with a mask 503, which is movable in the XYθ direction, and performs scanning exposure in the Y direction. This is a mask stage having a moving function. The substrate 507 is a glass substrate on which a pattern such as a transistor for manufacturing a liquid crystal display panel is formed by ordinary photolithography means. Reference numeral 508 denotes a substrate stage that can move in the XYθ direction while holding the substrate 507, and has a moving function for performing scanning exposure in the Y direction. A known mirror projection optical system 506 is configured by combining a convex mirror and a concave mirror, and projects a pattern image of the mask 503 positioned at a predetermined position by the mask stage 504 onto the substrate 507 at the same magnification. Reference numeral 501 denotes an illumination optical system that illuminates the mask 503 at the exposure position with light of a specific wavelength. By exposing the pattern on the mask 503 to the photosensitive layer on the substrate 507, the liquid crystal panel pixel pattern on the mask 503 is changed. This is for enabling transfer to the substrate 507.
[0010]
Reference numeral 505 denotes a main body structure on which a substrate stage 508 and a mask stage 504 are mounted. Reference numerals 511 and 512 denote motors for moving the stages 504 and 508 in the Y direction, respectively. Reference numerals 509 and 510 denote measuring instruments for monitoring the positions of the respective stages 504 and 508, that is, the mask 503 and the substrate 507, for example, a laser interferometer. Reference numeral 513 denotes a control circuit that moves the stages 504 and 508 in synchronization with each other by controlling the drive amounts to the motors 511 and 512 based on the stage position information from the laser interferometers 509 and 510 during scanning exposure. . As a control method, for example, the motor 511 is driven at a constant voltage so that the mask stage 504 travels at a constant speed, and the drive amount corresponding to the position of each stage 504, 508 measured by the laser interferometers 509, 510 is set to the motor. A method is used in which the substrate stage 508 is moved by being supplied to 512. Reference numeral 502 denotes the observation optical system described above with reference to FIG. 1, and reference numeral 514 denotes a processing apparatus for the observation optical system described above with reference to FIG.
[0011]
FIG. 2 is a flowchart showing the operation at the time of mask alignment in this exposure apparatus. At the time of alignment, as shown in this flowchart, the observation optical system for the reference mark 402 on the mask at each position shown in FIG. 4 while repeating detection at the movement interval and detection position designated at step S1, that is, at each designated position. The shift amount of the moving position of the system is calculated (steps S2 to S5), and correction data is automatically created and stored in the storage device 102 of the processing device 514 (step S6). As a result, the amount of deviation in driving of the next observation optical system is corrected.
[0012]
More specifically, as shown in FIG. 3, the observation optical system 502 is moved to each designated position di (d0, d1, d2,...) With respect to each reference mark 402 formed on the reference mask 301 at equal intervals α. ) Sequentially (step S2), but the actual movement position deviates from the designated position. Therefore, the reference mark 402 is imaged by the CCD camera 105 of the observation optical system 502 at each actually moved position (step S3), and the image processing circuit 101 of the processing device 514 is based on this imaging data. The deviation ei (e0, e1, e2,...) In the movement direction between the unique mark 401 and the reference mark 402 is detected as the deviation of the actual movement position with respect to the designated position, and stored together with the designated position di (step) S4). After completing the detection and storage at each moving position in this way, a corrected specified position that can match the actual moving position to the specified position based on the stored specified position di and deviation ei. Is created and stored in the storage device 102 of the processing device 514 (step 102). By driving the observation optical system 502 using the corrected designated position, the driving error of the observation optical system 502 is corrected, and the observation optical system 502 can be actually moved to the designated position.
[0013]
Data for obtaining the corrected designated position is created as follows. FIG. 6 is a diagram for explaining this principle. An ideal straight line 6 in the figure shows a relationship between the designated position and an ideal state where the actual moving position coincides. g (x) represents a position P that is actually moved when an arbitrary designated position X is given. f (x) is an inverse transformation of g (x), and the designated position necessary to move to the target position D is represented as X ′ satisfying g (X ′) = D. This X ′ is calculated as g ⁻¹ (D). From the definition of (x), X ′ = g ⁻¹ (D) = f (D). Therefore, the interval between the reference marks 402 on the mask is α, the designated position of the observation optical system 502 is di {d0 = 0, di = di-1 + α}, the measured deviation amount at each designated position is ei, and g When (x) is an appropriate interpolation function satisfying g (di) = di ei, an appropriate driving amount f (D) for the target position D of the observation optical system 502 is f (D) = g ⁻¹ (D ). However, g ⁻¹ (d) represents the inverse transformation of g (d). Therefore, for example, data representing g (x) or f (x) can be obtained based on the designated position di and the deviation measurement value ei, and this can be used as data for obtaining a corrected designated position.
[0014]
The present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented. For example, although the mirror projection optical system is used in the above-described embodiments, a lens projection optical system may be used instead. In the above-described embodiment, the correction of the movement error with respect to the single drive axis is shown. However, the feed error on the x and y planes is divided into a plurality of x and y axes, and the x and y axes are driven simultaneously. Similar correction processing is possible by performing measurement. In the above-described embodiment, the correction means for the designated position for the detection of the alignment mark on the mask which is the original plate is described. Similar correction processing can be performed for detection of a certain alignment mark.
[0015]
<Example of Device Manufacturing Method>
Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described.
FIG. 7 shows a flow of manufacturing a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). In step 1 (circuit design), a device pattern is designed. In step 2 (mask production), a mask on which the designed pattern is formed is produced. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4 (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 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, such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), and the like. including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).
[0016]
FIG. 8 shows a detailed flow of the wafer process. In step 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), an green film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a resist is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is arranged in a plurality of shot areas on the wafer and printed by exposure using the above-described exposure apparatus or exposure method. 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), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.
[0017]
By using the method of this embodiment, a large-sized device that has been difficult to manufacture can be manufactured at low cost.
[0018]
【The invention's effect】
As described above, according to the present invention, when the detection mark is detected by the detection means, the deviation amount between the designated movement position with respect to the detection means and the actual position after the detection means is corrected is corrected. The alignment mark can be reliably detected. In addition, alignment with higher accuracy is possible.
As a result, the production yield of devices such as liquid crystal panels is improved, and the production cost of devices is reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a flowchart showing the operation of the exposure apparatus of FIG.
FIG. 3 is a view showing a correction reference mask in the exposure apparatus of FIG. 5;
4 is a diagram showing an example of measurement at each measurement point in the exposure apparatus of FIG.
FIG. 5 is a schematic view of an exposure apparatus according to an embodiment of the present invention.
6 is an explanatory diagram showing the principle of driving error correction at each measurement point in the exposure apparatus of FIG. 5. FIG.
FIG. 7 is a flowchart showing a device manufacturing example using the exposure apparatus according to the present invention.
FIG. 8 is a flowchart showing a detailed flow of the wafer process in FIG. 7;
[Explanation of symbols]
100: Position specifying means, 101: Image processing circuit, 102: Storage device, 103: Drive axis correcting means, 104: Drive axis, 105: CCD camera, 106: Alignment mark, 301: Reference mask, α: On mask Reference mark interval, d0 to d i: target position of observation optical system, e0 to e i: measured value of deviation at each target position, 401: observation optical system specific mark, 402: reference on mask at each position Mark, 501: Illumination optical system, 502: Observation optical system, 503: Mask, 504: Mask stage, 505: Main body structure, 506: Mirror projection optical system, 507: Substrate, 508: Substrate stage, 509: Laser interference system 510: Laser interference system, 511: Motor, 512: Motor, 513: Control circuit, 514: Image processing device.

Claims (4)

In order to align the original plate, each of the alignment marks on the original plate has detection means for detecting the alignment marks by moving them to the respective detection positions in accordance with the designated movement positions, and an image of the original plate that has been aligned is obtained. In the exposure apparatus that performs exposure through the projection optical system, each alignment mark is detected by the detecting means, thereby obtaining and storing a shift amount between the designated movement position and the alignment mark, and storing the stored data in the stored data. based on, upon the detection of the alignment mark by the next of said detecting means corrects the movement position specified, comprising a control means for movement of said detecting means in accordance with the correction value, the control means, each designated The correction value is obtained by substituting each designated movement position into a function f (x) obtained by inversely transforming the function g (x) that gives the position at which the detection means actually moves with respect to the moved position. Exposure apparatus according to claim der Rukoto to obtain the correction value by using the method of that. In order to perform alignment of the substrate, each alignment mark on the substrate is moved to a detection position according to a designated movement position and detected, and is detected with respect to the aligned substrate. In an exposure apparatus that exposes a predetermined image via a projection optical system, each alignment mark is detected by the detection means, thereby obtaining and storing a shift amount between a designated movement position and the alignment mark. based on the stored data, upon detection of the alignment mark by the next of said detecting means, to correct the moving position specified, comprising a control means for movement of said detecting means in accordance with the correction value, said control means Is obtained by substituting each designated movement position into a function f (x) obtained by inversely transforming a function g (x) that gives a position at which the detection means actually moves for each designated movement position. An exposure apparatus utilizing the method of obtaining the correction value, characterized in der Rukoto to obtain the correction value. In order to align the original plate, each alignment mark on the original plate is detected by the detection means by moving the detection means to the detection position of each alignment mark according to the designated movement position. When the device is manufactured by exposing the image of the original plate aligned based on the projection optical system through the projection optical system, each alignment mark is detected by the detection means, thereby aligning with the designated moving position. The amount of deviation from the mark is obtained and stored, and on the basis of the stored data, when the alignment mark is detected by the detection means next time, the designated movement position is corrected, and the detection means is corrected according to the correction value. A device manufacturing method for moving ,
The correction value is obtained by substituting each designated movement position into a function f (x) obtained by inversely transforming a function g (x) that gives a position where the detection means actually moves with respect to each designated movement position. A device manufacturing method obtained by using a method of obtaining a correction value . In order to perform the alignment of the substrate, each alignment mark on the substrate is detected by the detection means by moving the detection means to the detection position of each alignment mark according to the designated movement position. When a device is manufactured by exposing a predetermined image to the substrate aligned based on the projection optical system, a specified movement is detected by detecting each alignment mark by the detection means. The amount of misalignment between the position and the alignment mark is obtained and stored, and on the basis of the stored data, in the next detection of the alignment mark by the detecting means, the designated moving position is corrected, and according to this correction value A device manufacturing method for moving the detection means ,
The correction value is obtained by substituting each designated movement position into a function f (x) obtained by inversely transforming a function g (x) that gives a position where the detection means actually moves with respect to each designated movement position. A device manufacturing method obtained by using a method of obtaining a correction value .

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