JP3462389B2 - Pattern transfer method - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a lithography process for a semiconductor device after a 256 Mbit level DRAM, a step & scan type reduction projection exposure apparatus is used in order to meet the need for a high NA optical system due to an increase in chip area and miniaturization of a circuit pattern. Is being introduced.

This step-and-scan type reduction projection exposure apparatus limits the irradiation range of light 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 configured to scan in opposite directions. In this step & scan type exposure apparatus, in order to prevent the pattern from being transferred while being displaced from a desired position, the arrangement of scan guide marks on the mask for guiding the mask in the scan movement direction of the mask mounting table and the scan movement direction. It is necessary to make the directions coincide with each other, and to make the scan movement direction of the mask mounting table coincide with the slit width direction of the slits (direction orthogonal to the central axis in the longitudinal direction of the slits).

[0004]

However, it is difficult to accurately match the directions, and conventionally, when a direction shift occurs, the mask and the scan movement direction are corrected each time. Therefore, there has been a problem that a lot of time and labor must be spent to make the correction.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a pattern transfer method capable of easily performing correction for suppressing transfer position deviation of a transfer pattern. .

[0006]

According to the present invention, a substrate placing table on which an exposed substrate is placed and which moves in a predetermined direction, and a pattern which is arranged above the substrate placing table and transferred to the exposed substrate are formed. A mask mounting table on which the mounted mask is mounted and which moves in a direction opposite to the moving direction of the substrate mounting table, and an exposed substrate mounted on the substrate mounting table via the mask mounted on the mask mounting table. A light source that exposes the substrate, an optical system that guides the light from the light source to the substrate to be exposed mounted on the substrate mounting table, and the light that is guided to the substrate to be exposed mounted on the substrate mounting table through the optical system. Slits that limit the projection range of
If, we have the means for a slit width of the slit in the variable
Using a step-and-scan type exposure apparatus
Pattern formed on the mask placed on the mask placing table
To transfer the substrate onto the substrate to be exposed mounted on the substrate mounting table.
In the turn transfer method, the slit width W of the slit
(Μm) is preferably set as follows.

A deviation amount (θ) 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 scanning moving direction) provided on the mask mounted on the mask mounting table. _The slit width W (μm) is set according to _m (radian) .

The slit width W (μm) is set according to the amount of deviation (θ _s (radian)) between the moving direction of the mask mounting table and the slit width direction of the slit (direction orthogonal to the longitudinal center axis of the slit). Set.

The slit width W (μm) is set according to the permissible amount (V _cd (μm)) with respect to the transfer position deviation of the transfer pattern transferred to the substrate to be exposed . θ _m (radian) and θ
The total deviation amount with _s (radian) (the absolute value of the sum of the deviation amounts when adding considering the sign) is | θ _m + θ _s |
(Radian), | θ _m + θ _s | · W <V _cd
The slit width W is set so as to satisfy the relationship .

Usually, the above θ _m (radian) has a finite value depending on the performance of the mask drawing device, and the above θ _s (radian) has a finite value depending on the performance of the exposure device. When pattern transfer is performed in such a situation, in the 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). Since the pattern is exposed, the resolution is lowered particularly in the pattern in the scan movement direction. It takes a lot of time and effort to correct θ _m (radian) and θ _s (radian) each time, and slit width W (μm)
The narrower is, the more the light source output must be increased.

According to the present invention, since the slit width can be varied, 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. It is possible to prevent the deterioration of the resolution of the pattern particularly in the scan movement direction.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a schematic configuration of a step-and-scan type reduction projection exposure apparatus according to this embodiment. FIG. 1A is a view seen from a direction perpendicular to a scan movement direction. FIG. 3B is a view seen from a direction parallel to the scan 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 the direction indicated by the arrow. Reference numeral 13 denotes a mask mounting table on which a mask 14 on which a circuit pattern 15 or the like to be transferred to the substrate 12 to be exposed is drawn is mounted.
Is configured to move in a direction parallel to and opposite to the moving direction of. A scan guide mark (not shown) for guiding the mask in the scan movement direction is also formed on the mask 14.

Reference numeral 16 denotes a light source for exposure, which exposes a photosensitive film (resist) formed on the substrate 12 to be exposed through the mask 14 with light from the light source, and the photosensitive film is drawn on the mask 14. A latent image corresponding to the formed pattern. Reference numeral 17 is a reduction lens, and 18 is a projection lens, which is configured to guide the light from the light source 16 to the surface of the exposed substrate 12. Reference numeral 19 is a slit that limits 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. A desired slit width can be obtained for this slit 19 by a slit width variable mechanism 20.

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). θ _m has a finite value depending on the performance of the mask drawing device. Further, as shown in FIG. 3, a shift amount (shift angle) θ _s (shift angle) between the moving direction 31 of the mask mounting table 31 and the slit width direction 33 of the slit 19 (direction orthogonal to the central axis 19a in the longitudinal direction of the slit) 33. Radians). θ _s has a 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 in the plus direction and the shift in the counterclockwise direction is in the minus direction, the total shift amount (relative shift amount) is | θ _m + θ _s |.

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

Therefore, the slit width W is set to the minimum necessary depending on the pattern size for which the slit width is desired to be resolved (the pattern to be resolved depends on the exposure wavelength to be used, the illumination conditions, the exposure process (including the resist process)). To optimize. When the allowable amount of transfer position deviation depending on the pattern size of the transferred pattern transferred to the substrate to be exposed is V _cd , the slit width is variable so that | θ _m + θ _s | · W <V _cd 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 in the scan movement direction.

Hereinafter, some specific examples will be described. The light source is KrF light with a wavelength λ = 248 nm, and NA =
Using a 0.7 step-and-scan type reduction projection exposure apparatus, | θ _m + θ _s | = 5 μ radian, and using an exposure process of k ₁ factor = 0.3, R = 106.3 nm
In the case of resolving the pattern _No. (result of calculation by R = k ₁ λ / NA), if the allowable amount V _cd of the pattern transfer position deviation is ± 10% of the pattern size, the total is 21.26 nm.
Therefore, in order to satisfy the above relational expression, the slit width W may be modified 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 μ radian, and using an exposure process with k ₁ factor = 0.3, R = 82.7.
In the case of resolving a pattern of nm (result of calculation by R = k ₁ · λ / NA), if the allowable amount V _cd of pattern transfer position deviation is ± 10% of the pattern size, a total of 16.6 n.
Therefore, the slit width W may be corrected to 3.32 mm or less in order to satisfy the above relational expression.

The light source is F ₂ light having a wavelength λ = 157 nm, and N
Using a step-and-scan type reduction projection exposure apparatus with A = 0.7, | θ _m + θ _s | = 5 μ radian, and using an exposure process with k ₁ factor = 0.3, R = 67.3 n
When resolving the pattern of m (result of calculation by R = k ₁ · λ / NA), if the allowable amount V _cd of the pattern transfer position deviation is ± 10% of the pattern size, a total of 13.46 n
Therefore, the slit width W may be corrected 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 implemented without departing from the spirit of the invention.

[0022]

According to the present invention, the exposure apparatus is provided with a 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. Therefore, it is possible to easily perform the correction, and it is possible to prevent the resolution of the pattern from being lowered particularly in the scan movement direction.

[Brief description of 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 showing a shift between a movement 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]

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 ... Movement direction of mask mounting table 32 ... Arrangement direction of scan guide marks 33 ... Slit width direction

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-130632 (JP, A) JP-A-1-175730 (JP, A) JP-A-10-92727 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (3)

(57) [Claims] 1. A substrate mounting table on which an exposed substrate is mounted and which moves in a predetermined direction, and a mask on which a pattern formed on the substrate mounting table to be transferred onto the exposed substrate is formed is mounted on the substrate mounting table. A mask placing table that moves in a direction opposite to the moving direction of the substrate placing table, a light source that exposes an exposed substrate placed on the substrate placing table through a mask placed on the mask placing table, and this light source An optical system that guides the light from the substrate to the exposed substrate mounted on the substrate mounting table, and a slit that limits the projection range of the light that is guided to the exposed substrate mounted on the substrate mounting table through the optical system. , A step-and-scan type having means for varying the slit width of this slit
In 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 an exposure apparatus, a moving direction of the mask mounting table and A pattern transfer method, characterized in that the slit width of the slit is set according to the amount of deviation from the arrangement direction of the scan guide marks provided on the mask mounted on the mask mounting table. 2. A substrate placing table on which an exposed substrate is placed and which moves in a predetermined direction, and a mask on which a pattern formed on the substrate placing table and transferred to the exposed substrate is formed is placed on the substrate placing table. A mask placing table that moves in a direction opposite to the moving direction of the substrate placing table, a light source that exposes an exposed substrate placed on the substrate placing table through a mask placed on the mask placing table, and this light source An optical system that guides the light from the substrate to the exposed substrate mounted on the substrate mounting table, and a slit that limits the projection range of the light that is guided to the exposed substrate mounted on the substrate mounting table through the optical system. , A step-and-scan type having means for varying the slit width of this slit
In a pattern transfer method of transferring a pattern formed on a mask mounted on the mask mounting table to an exposed substrate mounted on the substrate mounting table using an exposure device, a movement direction of the mask mounting table and the A pattern transfer method, wherein the slit width of the slit is set according to the amount of deviation of the slit from the slit width direction. 3. A substrate placing table on which an exposed substrate is placed and which moves in a predetermined direction, and a mask on which a pattern formed on the substrate placing table and to be transferred to the exposed substrate is formed is placed on the substrate placing table. A mask placing table that moves in a direction opposite to the moving direction of the substrate placing table, a light source that exposes an exposed substrate placed on the substrate placing table through a mask placed on the mask placing table, and this light source An optical system for guiding light from the substrate to be exposed on the substrate mounting table, and a slit for limiting 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 having means for varying the slit width of this slit
In 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 an exposure apparatus, a moving direction of the mask mounting table and the deviation between the arrangement direction of the scanning guide mark provided on the mounting mask to mask table and theta _m (radian), the deviation amount of the slit width direction of the moving direction and the slits of the mask table θ
_s (radian), and _Vcd (μm) is the permissible amount of the transfer pattern of the transfer pattern transferred onto the substrate to be exposed, the slit width W (μm) of the slit is | θ _m + θ _s | A pattern transfer method characterized by setting such that W <V _cd .