JPH11340118A - Exposure apparatus and pattern transfer method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To easily perform a correction for suppressing a transfer position shift of a transfer pattern. SOLUTION: A substrate mounting table 11 on which a substrate to be exposed 12 is mounted and moves in a predetermined direction, and a mask 14 on which a pattern 15 to be transferred to the substrate to be exposed 12 is formed, and scans the substrate mounting table 11. A mask mounting table 13 moving in a direction opposite to the moving direction, and a mask 14 mounted on the mask mounting table 13
A light source 16 for exposing the substrate to be exposed 12 through
Optical systems 17 and 18 for guiding the light from
In a step-and-scan type exposure apparatus having a slit 19 for limiting a projection range of light guided to the substrate 12 through the optical system, a mechanism 20 for changing a slit width of the slit is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-and-scan type exposure apparatus and a pattern transfer method using the same.

[0002]

2. Description of the Related Art In a lithography process of a semiconductor device of a 256 Mbit level DRAM or later, a step-and-scan type reduced projection exposure apparatus is required to meet a demand for an increase in chip area and a necessity of a high NA optical system by miniaturization of a circuit pattern. Has begun to be introduced.

In this step & scan type reduction projection exposure apparatus, a light irradiation range is limited by a slit, and
The substrate mounting table on which the substrate to be processed is mounted and the mask mounting table on which the mask is mounted are scanned in opposite directions. In this step & scan type exposure apparatus, in order to avoid transfer of a pattern from a desired position, a scan moving direction of the mask mounting table and an array of scan guide marks on the mask for guiding the mask in the scan moving direction. It is necessary to make the directions coincide with each other, and make the scan movement direction of the mask mounting table coincide with the slit width direction of the slit (the direction orthogonal to the longitudinal central axis of the slit).

[0004]

However, it is difficult to accurately match the directions. Conventionally, when a direction shift occurs, correction of a mask or correction of a scan moving direction is performed each time. Therefore, there is a problem that much time and labor must be spent for making the correction.

An object of the present invention is to provide an exposure apparatus and a pattern transfer method capable of easily performing a correction for suppressing a transfer position shift of a transfer pattern. The purpose is.

[0006]

An exposure apparatus according to the present invention comprises a substrate mounting table for mounting a substrate to be exposed and moving in a predetermined direction, a substrate mounting table disposed above the substrate mounting table, and transferred to the substrate to be exposed. A mask on which a mask having a pattern formed thereon is mounted and which moves in a direction opposite to the moving direction of the substrate mounting table; and a mask mounted on the substrate mounting table via a mask mounted on the mask mounting table. A light source for exposing the exposed substrate,
An optical system for guiding light from the light source to the substrate to be exposed mounted on the substrate mounting table, and limiting a projection range of light guided to the substrate to be exposed mounted on the substrate mounting table through the optical system. In a step-and-scan type exposure apparatus having a slit, a means for changing a slit width of the slit is provided (claim 1).

In the pattern transfer method using the exposure apparatus, it is preferable that the slit width W (μm) of the slit is set as follows. The shift amount (θ _m (radian) between the moving direction of the mask mounting table and the arrangement direction of the scan guide marks (marks for guiding the mask in the scan moving direction) provided on the mask mounted on the mask mounting table. )), The slit width W (μm) is set (claim 2).

The slit width W (μm) is determined according to the shift amount (θ _s (radian)) between the moving direction of the mask mounting table and the slit width direction of the slit (a direction orthogonal to the longitudinal central axis of the slit). Set (Claim 3).

A slit width W (μm) is set according to an allowable amount (V _cd (μm)) for a transfer position shift of a transfer pattern transferred to the substrate to be exposed. The total deviation between θ _m (radian) and θ _s (radian) (the absolute value of the sum of the deviations when added considering the sign) is |
When θ _m + θ _s | (radian), | θ _m + θ _s
The slit width W is set so as to satisfy the relationship | · W <V _cd (claim 5).

Usually, θ _m (radian) has a finite value depending on the performance of the mask drawing apparatus, and θ _s (radian) has a finite value depending on the performance of the exposure apparatus. When pattern transfer is performed in such a situation, in a pattern near the limit resolution of the exposure apparatus, the transfer position is shifted by | θ _m + θ _s | · W (μm) with respect to the slit width W (μm). Exposure is performed, and the resolution is reduced particularly in a pattern in the scanning movement direction. It takes a lot of time and effort to correct θ _m (radian) and θ _s (radian) each time, and the slit width W (μm)
When the distance is reduced, the output of the light source must be increased accordingly.

In the present invention, by providing the means for varying the slit width, the slit width W (μm) can be optimized according to the pattern size to be resolved, so that the transfer position deviation can be easily corrected. In particular, it is possible to prevent the resolution of the pattern from decreasing in the scanning movement direction.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a schematic configuration of a step & scan type reduction projection exposure apparatus according to the present embodiment, and FIG. 1 (a) is a diagram viewed from a direction perpendicular to a scanning movement direction. FIG. 6B is a diagram viewed from a direction parallel to the scanning movement direction.

In FIG. 1, reference numeral 11 denotes a substrate mounting table on which a substrate 12 to be exposed such as a semiconductor wafer is mounted, and is configured to move in a direction indicated by an arrow. Reference numeral 13 denotes a mask mounting table for mounting a mask 14 on which a circuit pattern 15 or the like to be transferred to the substrate 12 is drawn.
Is configured to move in a direction parallel to and in a direction opposite to the moving direction of the moving object. Note that the mask 14 is also formed with a scan guide mark (not shown) for guiding the mask in the scanning movement direction.

Reference numeral 16 denotes a light source for exposure, which exposes a photosensitive film (resist) formed on the substrate 12 to be exposed with light from the light source through a mask 14 and draws the photosensitive film on the mask 14. A latent image corresponding to the shifted pattern is formed. Reference numeral 17 denotes a reduction lens, and reference numeral 18 denotes a projection lens, which is configured to guide light from the light source 16 to the surface of the substrate 12 to be exposed. Reference numeral 19 denotes a slit for limiting the irradiation range of the light from the light source 16 and has a rectangular opening having a slit width W and a slit length L. The slit 19 has a slit width variable mechanism 20 so that a desired slit width can be obtained.

Here, as shown in FIG. 2, a shift amount (shift) between the moving direction 31 of the mask mounting table and the arrangement direction 32 of the scan guide marks 21 formed on the mask mounted on the mask mounting table. Angle) θ _m (radian). The theta _m are those with a finite value in the performance of the mask writer. Further, as shown in FIG. 3, a shift amount (shift angle) θ _s (shift angle) between the movement direction 31 of the mask mounting table and the slit width direction 33 of the slit 19 (direction orthogonal to the longitudinal central axis 19 a of the slit) 33. Radians). θ _s has a certain finite value depending on the performance of the exposure apparatus. For example, when the shift in the clockwise direction of θ _m and θ _s is the plus direction and the shift in the counterclockwise direction is the minus direction, the total shift amount (relative shift amount) is | θ _m + θ _s |.

In such a case, a pattern near the limit resolution of the exposure apparatus is exposed by shifting the transfer position by | θ _m + θ _s | · W with respect to the slit width W during scan exposure. The resolution is reduced in the pattern in the scanning movement direction. Such a problem is alleviated as the slit width is reduced, and hardly affects a pattern much larger than the limit resolution of the exposure apparatus. However, if the slit width is reduced, the output of the exposure light source must be increased accordingly, and KrF, ArF, F
It greatly depends on the limit of the output of the excimer light source such as ₂ .

Therefore, the slit width W is set to the minimum necessary in accordance with the pattern size for which the slit width is to be resolved (the pattern to be resolved depends on the exposure wavelength to be used, illumination conditions, and the exposure process (including the resist process)). To be optimized. If the capacity of the transfer position deviation that depends on the pattern size to be resolved in a transfer pattern transferred to the exposed substrate was _{V cd, | θ m + θ} s | such that · W <V _cd, slit width variable By adjusting and optimizing the slit width W by the mechanism 20, it is possible to prevent a decrease in the resolution of the pattern particularly in the scanning movement direction.

Hereinafter, description will be made with reference to some specific examples. The light source is KrF light having a wavelength λ = 248 nm, and NA =
R = 106.3 nm using a step & scan type reduction projection exposure apparatus of 0.7, | θ _m + θ _s | = 5 μradian, and an exposure process of k ₁ factor = 0.3.
(Result of calculation using R = k ₁ · λ / NA), if the allowable amount V _cd of the pattern transfer position shift is ± 10% of the pattern size, a total of 21.26 nm
In order to satisfy the above relational expression, the slit width W may be corrected to 4.25 mm or less.

The light source is ArF light having a wavelength λ = 193 nm,
Using a step-and-scan type reduction projection exposure apparatus with NA = 0.7, | θ _m + θ _s | = 5 μradian, and R = 82.7 using an exposure process with a k ₁ factor = 0.3.
In the case of resolving a pattern of nm (calculation result by R = k ₁ λ / NA), when the allowable amount V _cd of the pattern transfer position shift is ± 10% of the pattern size, a total of 16.6 n
m, the slit width W may be corrected to 3.32 mm or less to satisfy the above relational expression.

The light source is F ₂ light having a wavelength λ = 157 nm, and N ₂
Using a step & scan type reduction projection exposure apparatus with A = 0.7, | θ _m + θ _s | = 5 μradian, R = 67.3n using an exposure process with a k ₁ factor = 0.3
When resolving the pattern of m (calculation result by R = k ₁ λ / NA), the allowable amount V _cd of the pattern transfer position shift is ± 10% of the pattern size and 13.46 n in total.
m, the slit width W may be modified to 2.69 mm or less in order to satisfy the above relational expression.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
Various modifications can be made without departing from the spirit of the invention.

[0022]

According to the present invention, the exposure apparatus is provided with means for varying the slit width, and the slit width is optimized according to the pattern size to be resolved, thereby suppressing the transfer position shift of the transfer pattern. Correction can be easily performed, and in particular, it is possible to prevent a decrease in the resolution of the pattern in the scanning movement direction.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a schematic configuration of a step-and-scan type reduction projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a shift between a moving direction of a mask mounting table and an arrangement direction of scan guide marks.

FIG. 3 is a diagram showing a shift between a moving direction of a mask mounting table and a slit width direction of a slit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Substrate mounting table 12 ... Substrate to be exposed 13 ... Mask mounting table 14 ... Mask 15 ... Circuit pattern 16 ... Light source 17 ... Reduction lens 18 ... Projection lens 19 ... Slit 20 ... Slit width variable mechanism 21 ... Scan guide mark 31 ... Mask Moving direction of the mounting table 32: Arrangement direction of scan guide marks 33: Slit width direction

Claims (5)

[Claims] A substrate mounting table for mounting a substrate to be exposed and moving in a predetermined direction; and a mask disposed above the substrate mounting table and having a pattern formed thereon to be transferred to the substrate to be exposed. A mask mounting table that moves in a direction opposite to the moving direction of the substrate mounting table, a light source that exposes a substrate to be exposed mounted on the substrate mounting table via a mask mounted on the mask mounting table, An optical system that guides light from the target to the substrate to be exposed mounted on the substrate mounting table, and a slit that limits a projection range of light guided to the substrate to be exposed mounted on the substrate mounting table through the optical system. A step-and-scan type exposure apparatus comprising: means for varying the slit width of the slit. 2. A pattern transfer method for transferring a pattern formed on a mask mounted on the mask mounting table to a substrate to be exposed mounted on the substrate mounting table using the exposure apparatus according to claim 1. Wherein the slit width of the slit is set in accordance with a shift amount between a moving direction of the mask mounting table and an arrangement direction of scan guide marks provided on the mask mounted on the mask mounting table. Pattern transfer method. 3. A pattern transfer method for transferring a pattern formed on a mask mounted on the mask mounting table to a substrate to be exposed mounted on the substrate mounting table, using the exposure apparatus according to claim 1. Wherein the slit width of the slit is set in accordance with a shift amount between a moving direction of the mask mounting table and a slit width direction of the slit. 4. A pattern transfer method for transferring a pattern formed on a mask mounted on the mask mounting table to a substrate to be exposed mounted on the substrate mounting table, using the exposure apparatus according to claim 1. 3. The pattern transfer method according to claim 1, wherein a slit width of the slit is set in accordance with an allowable amount of a transfer position of a transfer pattern transferred to the substrate to be exposed. 5. A pattern transfer method for transferring a pattern formed on a mask mounted on the mask mounting table to an exposed substrate mounted on the substrate mounting table using the exposure apparatus according to claim 1. In the above, the shift amount between the moving direction of the mask mounting table and the arrangement direction of the scan guide marks provided on the mask mounted on the mask mounting table is defined as θ _m (radian). When the amount of deviation from the slit width direction of the slit is θ _s (radian), and the allowable amount for the transfer position deviation of the transfer pattern transferred to the substrate to be exposed is V _cd (μm), the slit width W of the slit is W ([mu] m) and _{| θ m + θ s | ·} W < pattern transfer method, characterized in that set to be V _cd.