JPH10199794A - Aligner and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of dislocation by equipping an exposer with a quantity-of-inclination computing means which computes the quantity of inclination of a board placed on an exposure stage, and a quantity-of-expansion-and-contraction compensating means which compensates the quantity-of-expansion-and-contraction computed by the computed quantity-of-inclination. SOLUTION: The coordinates of position detecting marks 16 made at optional ten shots out of sixty four shots allotted to a board 6 are measured. Subsequently, the quantity of inclination of the shot where the coordinate of the position detecting mark 16 is measured is measured. The measurement point a1 and the measurement point a2 distances G1 separated from the center O of the shot are set at the corners of the shot, and the height of the measurement point a1 and the height of the measurement point a2 being set are measured. Next, light is applied toward the measurement points a1 and a2, and an exposure stage 5 is moved up and down so that the reflected light may focus at an autofocus sensor 1, and the heights of the measurement points a1 and a2 are measured. The quantity of inclination of one shot is computed from the measured heights of the measurement points a1 and a2. Successively, the coordinate of the position detecting mark is compensated by the quantity of inclination of the shot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an exposure apparatus and method.

[0002]

2. Description of the Related Art Conventionally, as an exposure apparatus, for example, a lens reduction projection exposure apparatus moves a substrate (silicon wafer) mounted on an exposure stage step by step by one shot to form a pattern on a shot assigned to the substrate. Expose. Here, a shot is an area irradiated by one exposure, and for example, 64 (= 8 × 8) shots are assigned to one substrate (see FIG. 2).

[0003] The substrate mounted on the exposure stage is usually expanded and contracted by the influence of a process such as a high-temperature process. Therefore, the step amount of the substrate to be step-moved is set in accordance with the amount of expansion and contraction. At this time, the amount of expansion and contraction is calculated from the difference from the theoretical value by statistically processing, for example, 10 shots of the coordinates of the position detection mark formed on the shot, and the coordinates of all shots are calculated based on the calculated amount of expansion and contraction. Is done.

[0004]

However, the substrate may not only expand and contract due to the effects of a process such as a high-temperature process, but may also undulate or tilt when viewed in an enlarged manner (see FIG. 5). Conventionally, even when the substrate is tilted, the coordinates of the position detection marks are measured as they are, so that an error occurs in the amount of expansion and contraction. That is, since an error (x / cos θ−x) is generated in the coordinates of the position detection mark measured as shown in FIG. 6, if the pattern is exposed as it is, a misalignment will occur due to the error.

Accordingly, an object of the present invention is to provide an exposure apparatus and method capable of exposing a pattern without causing misalignment when calculating the amount of expansion and contraction of a substrate and performing step movement.

[0006]

To achieve the above object, an exposure apparatus according to a first aspect of the present invention includes an expansion / contraction amount calculating means for calculating an expansion / contraction amount of a substrate placed on an exposure stage. An exposure apparatus for moving and exposing the substrate by a step amount according to the calculated expansion and contraction amount, and an inclination amount calculating means for calculating an inclination amount of the substrate mounted on the exposure stage; An expansion / contraction amount correction unit that corrects the calculated expansion / contraction amount with the amount of inclination.

A plurality of shots indicating an area irradiated in one exposure are assigned to the substrate, and the expansion / contraction amount calculating means measures a coordinate of a position detection mark formed on the shot. It is preferable that a means for correcting the amount of expansion and contraction is provided, and the means for correcting the amount of expansion and contraction corrects the coordinates of the measured position detection mark with the amount of inclination. Further, the tilt amount calculating means sets a measurement area where at least two points of the shot are irradiated with light from a light source, and sets the substrate such that the light reflected by the set measurement area is focused. Preferably, the mounted exposure stage is moved, and the tilt amount is calculated from the movement amount. Further, it is preferable that the present invention is applied to a lens reduction projection exposure apparatus.

An exposure method according to claim 5, wherein the amount of expansion and contraction of the substrate placed on the exposure stage is calculated, and the substrate is exposed by moving the substrate by a step amount corresponding to the calculated amount of expansion and contraction. Wherein the amount of inclination of the substrate placed on the exposure stage is calculated, and the calculated amount of expansion / contraction is corrected using the calculated amount of inclination.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure apparatus and method according to the present invention will be described. The exposure apparatus according to the present embodiment is applied to a lens reduction projection exposure apparatus. FIG. 1 is a diagram schematically showing a configuration of a main part of an exposure apparatus according to an embodiment. The exposure apparatus includes an apparatus body 1, a reduction projection lens 4, an exposure stage 5, and the like. Further, the apparatus main body 1 is provided with a control unit (not shown) for controlling the whole, and the control unit executes a control program such as an expansion / contraction amount calculation processing procedure to be described later to move the exposure stage 5 step by step. A pattern is exposed on a substrate 6 such as a silicon wafer mounted on an exposure stage 5 via a reduction projection lens 4.

FIG. 2 is a plan view of the substrate 6. Shots indicating regions irradiated by one exposure are assigned to 8 × 8 (= 64) locations on one substrate 6. Further, in this exposure apparatus, a tilt amount measuring mechanism configured to measure the tilt amount of the substrate placed on the exposure stage 5 from the light source 7, the vibrator 3, the light receiving slit 2, the autofocus sensor 9, the relay substrate 8, and the like is configured. The exposure stage 5 is moved up and down so that the light emitted from the light source 7 toward the substrate 6 is focused by the autofocus sensor 9, and the amount of tilt θ of the shot is measured from the amount of movement as described later. Substrate 6 such as a silicon wafer mounted on exposure stage 5
As described above, the length of the exposure stage 5 is expanded or contracted or inclined by the influence of the process such as the high-temperature process. Therefore, the step amount for moving the exposure stage 5 must be set in consideration of these factors.

FIG. 3 is a flowchart showing the procedure for calculating the amount of expansion and contraction. First, the coordinates x of the position detection marks 16 formed in arbitrary 10 shots among the 64 shots allocated to the substrate 6 are measured (step S1). FIG. 5 is a view showing a shot in which the position detection mark 16 is formed. FIG. 1A shows a plane of a shot, and FIG. 1B shows its inclination.

Subsequently, the inclination θ of the shot at which the coordinates of the position detection mark 16 are measured is measured (step S).
2). FIG. 4 is a flowchart showing a procedure for measuring the shot tilt amount θ. The measurement point a1 and the measurement point a2 which are away from the center O of the shot by the distance G are set at the corners of the shot (step S11), and the height F1 of the set measurement point a1 and the height F2 of the measurement point a2 are measured (step S11). Step S12).
Light is emitted from the light source 7 toward the set measurement points a1 and a2, and the exposure stage 5 is moved up and down so that the reflected light is focused by the autofocus sensor 9. Height F1 and height F2 of measurement point a2
Is measured. The inclination amount θ of one shot is calculated from the measured heights F1 and F2 according to [Equation 1] (step S13).

[0013]

## EQU1 ## θ = tan-1 ((F1-F2) / 2G)

Then, the coordinate x of the position detection mark measured in step S1 is corrected by [Equation 2] using the inclination θ of the shot measured in step 2 (step S2).
3).

[0015]

Xa = x / θ-x

Here, x is the coordinates of the position detection mark 16 before correcting the shot tilt amount θ, and xa is the coordinates of the position detection mark 16 after correcting the shot tilt amount θ. FIG. 6 is a diagram showing the relationship between the shot inclination and x and θ.

Statistical processing is performed on the coordinates xa of the position detection mark 16 in which the shot tilt amount θ has been corrected, and the distance from the center of the substrate 6 to the position detection mark 16 is calculated by the theoretical value A and the measured value A ′.
Is calculated according to [Equation 3] (step S4).

[0018]

## EQU3 ## The amount of expansion and contraction B = (A'-A) / A

Thus, the amount of expansion and contraction of the substrate 6 expanded and contracted by a process such as a high-temperature process is accurately calculated.
Thereafter, with the step pitch between shots as C, the exposure apparatus sequentially moves the exposure stage 5 by a step amount shown in [Equation 4] to expose a pattern to each shot.

[0020]

## EQU00004 ## Step amount = (1 + extension / contraction amount B) .times.step pitch C

As described above, according to the exposure apparatus of the present embodiment, the substrate 6 can be accurately step-moved by calculating the amount of expansion and contraction in consideration of the amount of inclination θ of each shot, and misalignment occurs. The pattern can be exposed on the substrate without any need. In the above-described embodiment, only the X coordinate is shown. However, the Y coordinate may be calculated in consideration of the inclination θ of the shot. Further, in the present embodiment, the tilt amount θ is measured only for the shot in which the position detection mark 16 is measured. However, the statistical processing may be performed by measuring the tilt amount θ for all shots allocated to the substrate 6. Good. Furthermore, it is also possible to select and measure only shots for which the amount of inclination of each shot is known by performing statistical processing.

[0022]

According to the exposure apparatus of the first aspect of the present invention, the amount of expansion and contraction of the substrate placed on the exposure stage is calculated by the amount of expansion and contraction calculation means, and the step corresponding to the calculated amount of expansion and contraction is performed. When exposing the substrate by moving the substrate by an amount, the amount of inclination of the substrate mounted on the exposure stage is calculated by the amount of inclination calculating means, and the calculated expansion and contraction is performed by the calculated amount of inclination by the expansion and contraction amount correcting means. Since the amount is corrected, the pattern can be exposed without causing misalignment when calculating the amount of expansion and contraction of the substrate and moving the substrate in steps.

According to the exposure apparatus of the present invention, a plurality of shots indicating an area irradiated by one exposure are assigned to the substrate, and the expansion / contraction amount calculating means is provided for the shot. It is provided with coordinate measuring means for measuring the coordinates of the position detection mark, and the expansion and contraction amount correction means corrects the measured coordinates of the position detection mark with the inclination amount,
The accuracy of the statistical processing can be improved by performing a plurality of measurements for each shot. Further, the measurement of the coordinates of the position detection mark and the calculation of the amount of tilt can be performed within the same shot, and the efficiency can be improved.

According to the third aspect of the present invention, the tilt amount calculating means sets a measurement area where at least two points of the shot are irradiated with light from a light source, and sets the measurement area in the set measurement area. The exposure stage on which the substrate is mounted is moved so that the reflected light is focused, and the inclination amount is calculated from the movement amount, so that an inclination amount measurement mechanism can be easily attached, and the exposure stage By utilizing the function of, the amount of tilt can be easily measured.

According to the exposure apparatus of the fourth aspect, since the present invention is applied to a lens reduction projection exposure apparatus, pattern misalignment can be eliminated in the lens reduction projection exposure apparatus.

According to the exposure method of the present invention, the amount of expansion and contraction of the substrate mounted on the exposure stage is calculated, and the substrate is exposed by moving the substrate by a step amount according to the calculated amount of expansion and contraction. In the exposure method, the amount of inclination of the substrate placed on the exposure stage is calculated, and the calculated amount of expansion and contraction is corrected with the calculated amount of inclination. The pattern can be exposed without causing misalignment.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a main part of an exposure apparatus according to an embodiment.

FIG. 2 is a diagram showing a plane of a substrate 6;

FIG. 3 is a flowchart illustrating an expansion / contraction amount calculation processing procedure;

FIG. 4 is a flowchart showing a procedure for measuring a shot tilt amount θ.

FIG. 5 is a view showing a shot on which a position detection mark is formed.

FIG. 6 is a diagram illustrating a relationship between a shot inclination and x and θ.

[Explanation of symbols]

1 ... device main body, 2 ... light receiving slit, 3 ... vibrator,
4 ... reduction projection lens, 5 ... exposure stage, 6 ... substrate, 7 ... light source, 16 ... position detection mark

Claims (5)

[Claims] An exposure apparatus, comprising: an expansion / contraction amount calculating unit configured to calculate an expansion / contraction amount of a substrate placed on an exposure stage, wherein the exposure apparatus moves and exposes the substrate by a step amount corresponding to the calculated expansion / contraction amount. A tilt amount calculating unit that calculates a tilt amount of the substrate placed on the exposure stage; and a stretching amount correcting unit that corrects the calculated stretching amount with the calculated tilt amount. Exposure equipment. 2. A plurality of shots indicating an area irradiated by one exposure are assigned to the substrate, and the expansion / contraction amount calculating means measures a coordinate of a position detection mark formed on the shot. 2. The apparatus according to claim 1, wherein the expansion / contraction amount correction unit corrects the coordinates of the measured position detection mark with the inclination amount.
Exposure apparatus according to the above. 3. The tilt amount calculating means sets a measurement area where at least two positions of the shot are irradiated with light from a light source, and focuses the light reflected by the set measurement area. 3. The exposure apparatus according to claim 2, wherein the exposure stage on which the substrate is mounted is moved, and the amount of tilt is calculated from the amount of movement. 4. The exposure apparatus according to claim 1, wherein the exposure apparatus is applied to a lens reduction projection exposure apparatus. 5. An exposure method for calculating an amount of expansion and contraction of a substrate mounted on an exposure stage, and moving and exposing the substrate by a step amount according to the calculated amount of expansion and contraction, wherein the substrate is mounted on the exposure stage. An exposure method comprising: calculating a calculated tilt amount of the substrate; and correcting the calculated expansion / contraction amount by the calculated tilt amount.