JP6771997B2 - Exposure equipment, exposure method, and article manufacturing method - Google Patents

Description

The present invention relates to an exposure apparatus, an exposure method, and an article manufacturing method.

In a lithography process, which is one of the processes for manufacturing articles such as semiconductor devices and liquid crystal display devices, an exposure device that transfers an original pattern to an exposure region on a substrate via a projection optical system is used. With the recent miniaturization of the above-mentioned articles, it is required to adjust the imaging performance of the projection optical system and accurately transfer the pattern of the original plate to the substrate at a predetermined magnification. For example, the exposure apparatus described in Patent Document 1 includes an optical member that adjusts imaging performance such as distortion and imaging magnification of a projection optical system.

Japanese Unexamined Patent Publication No. 2011-39172

However, in the exposure apparatus of the above patent document, in order to cope with the increase in the exposure area due to the increase in the size of the substrate, for example, it is necessary to increase the size of the member of the optical element for adjusting the imaging performance, and the projection optics The system becomes larger.

An object of the present invention is, for example, to provide an exposure apparatus which is advantageous in terms of securing the size of the apparatus and a wide exposure area.

In order to solve the above problems, the present invention is an illumination optical system for illuminating a mask, and an illumination optical system including a slit having an opening for shaping light.
It has a projection optical system that projects an image of the mask illuminated by light from the illumination optical system onto a substrate.
An exposure apparatus that exposes a substrate while changing the relative position between the mask and the substrate in a predetermined direction.
It is characterized in that the curvature of the curve defining the aperture is changed according to the NA of the projection optical system.

According to the present invention, for example, it is possible to provide an exposure apparatus that is advantageous in terms of securing the size of the apparatus and a wide exposure area.

It is the schematic of the exposure apparatus which concerns on 1st Embodiment. It is a figure which shows the shape of the slit included in the illumination optical system which concerns on 1st Embodiment. It is a longitudinal aberration diagram about astigmatism which shows the focus characteristic of a projection optical system. It is a figure which shows the effective part of a refracting member. It is a figure which shows the slit shape when the slit width is enlarged. It is a figure which shows the shape of the effective part of the required refracting member corresponding to the slit width of FIG. It is a figure which shows the shape of the slit which made the curvature smaller than the curvature of FIG. It is a figure which shows the shape of the effective part of the required refraction member corresponding to the slit width of FIG. It is a figure which shows the shape of the slit which concerns on 2nd Embodiment. It is a figure which shows the structure of the slit shape variable mechanism. It is a figure which shows an example of the structure of an aperture.

Hereinafter, embodiments for carrying out the present invention will be described with reference to drawings and the like.

(First Embodiment)
FIG. 1 is a schematic view of an exposure apparatus according to a first embodiment of the present invention. The exposure apparatus of this embodiment can be used, for example, in a lithography process in a manufacturing process of a flat panel such as a liquid crystal display device or an organic EL device. In particular, in the present embodiment, the exposure apparatus scans the relative positions of the mask (reticle, original plate) and the substrate in synchronization with the scanning direction by a step-and-scan method, and scans the pattern image formed on the mask. A scanning projection exposure apparatus that transfers (exposes) onto a substrate.

The exposure apparatus of the present embodiment has a mask stage (first holding portion) 2 that holds and moves a mask (object) 1 on which a circuit pattern of a device to be manufactured is drawn, and a substrate (board) 3. A substrate stage (second holding portion) 4 for holding is provided. Further, it includes an illumination optical system IL that illuminates the mask 1, a projection optical system PO that projects the pattern of the mask 1 on the substrate 3, and a control unit C. A mask stage 2 holding the mask 1 is arranged between the illumination optical system IL and the projection optical system PO. The illumination optical system IL includes a light source, and for example, a high-pressure mercury lamp can be used. However, the light source can be arbitrarily selected to be suitable for the device to be manufactured. The illumination optical system IL is provided with a slit 5, light from a light source passes through the slit 5 to illuminate the mask 1, and the projection optical system PO holds an image of the mask 1 pattern on the substrate stage 4. It is projected onto the substrate 3. The slit 5 has a shape that matches the shape of the good image region of the projection optical system PO. The light that has passed through the slit 5 is shaped into a shape that matches the good image region of the projection optical system PO. The control unit C includes a CPU and a memory (ROM, RAM, etc.), and controls each part of the exposure apparatus to control the exposure process of the substrate 3. The memory has a table in which the NA of the projection optical system (information on the imaging performance of the projection optical system) and the width of the transmission portion 52 (shown in FIG. 2) suitable for the NA in the Y direction (predetermined direction) are associated with each other. It is remembered. Further, a table in which the slit width Wb of the transmission portion 52 in the Y direction (shown in FIG. 2) and the curvature of the arc of the transmission portion 52 changed according to the width are associated with each other is stored. The NA of the projection optical system is input to the exposure apparatus by the user according to the pattern of the mask 1 and the desired resolving power.

The projection optical system PO includes a first refracting member 6, a trapezoidal mirror 7 having a reflecting surface composed of two plane mirrors, a first concave mirror 8, and an aperture 12 in order along the traveling direction of light from the mask 1. It includes a convex mirror 9, a second concave mirror 10, and a second refracting member 11. The first concave mirror 8 and the second concave mirror 10 may be integrally configured. In FIG. 1, the direction from the substrate 3 to the mask 1 (the optical axis direction of the projection optical system PO) is orthogonal to the + z direction and the z direction, and the direction from the convex mirror 9 to the first concave mirror 8 is the + y direction, the z direction and y. The direction forming the right-handed system with respect to the direction is defined as the + x direction.

A photoresist sensitive to exposure light is applied to the substrate 3, and by developing the exposure pattern, a circuit pattern drawn on the mask 1 is formed on the substrate 3. At the time of exposure, the relative positions of the mask stage 2 and the substrate stage 4 are synchronized and scanned in the y direction, so that a wider area can be exposed than when no scanning is performed. The convex mirror 9 is the pupil of the projection optical system PO. The numerical aperture (NA) of the projection optical system PO can be changed by changing the diameter of the diaphragm 12 provided on the convex mirror 9.

FIG. 2 is a diagram showing the shape of the slit 5 provided in the illumination optical system IL according to the present embodiment. In the projection optical system PO of the present embodiment including the convex mirror 9, the first concave mirror 8 and the second concave mirror 10, an off-axis arc-shaped good image region can be used. Therefore, the slit 5 has an arc shape having a width (length in the y direction) W shown in FIG. The slit 5 has a light-shielding portion 51 and a transmission portion 52, and can be made of a metal such as iron. Good imaging performance can be obtained by forming the transmission portion 52 into a shape that matches the good image region of the projection optical system PO.

The first refraction member 6, the second refraction member 11, and the third refraction member 12 are correction optical systems for correcting the imaging performance of the projection optical system PO, such as magnification and aberration. Each refracting member is composed of an aspherical lens or plate, a wedge-shaped optical member, or the like.

FIG. 3 is a longitudinal aberration diagram relating to astigmatism showing the focus characteristics of the projection optical system PO. The vertical axis is the y direction and the horizontal axis is the defocus amount. The curve S indicates the amount of defocus on the sagittal image plane, and the curve M indicates the amount of defocus on the meridional image plane. It can be seen that the region where the defocus amount of each image plane becomes zero is the good image region of the projection optical system PO, and the good image region is off-axis. Since the sizes of the first refracting member 6 and the third refracting member 12 are limited due to the arrangement relationship, not all the good image areas can be used. As shown in FIG. 3, the usable area covers only a part of the good image area.

FIG. 4 is a diagram showing an effective portion P of the refracting member 6. Here, of the three refraction members, the refraction member 6 will be described as an example. The dimension L of the refracting member 6 in the y direction is limited by the arrangement space in the projection optical system PO and the like. The dimensional difference d at the position where the difference between the dimension of the effective portion P in the y direction and the dimension L of the refracting member 6 in the y direction is the smallest is required to be a certain value or more due to processing restrictions and holding restrictions of the refracting member 6. Become. However, since the dimension L of the refracting member 6 in the y direction is limited, it may not be possible to obtain an effective portion P having a size sufficiently covering the good image region of the projection optical system PO. Therefore, the usable area is limited as shown in FIG. Similarly, the good image region can be limited by the restrictions on the outer shape of the first concave mirror 8 and the second concave mirror 10. The maximum height of the limited good image area is set to the curvature R of the arc of the transmission portion 52, and the slit shape that uses only the usable good image area is determined by moving the arc in the y direction by the width of the usable area. It is possible to do.

ＮＡを小さくした場合、各光学部材での光束径が小さくなる。そのため各光学部材の有効径を変更することなく、スリット５の幅Ｗを広くすることが可能となる。スリットの幅Ｗを広くすることにより走査露光の際の積算光量が増え露光時間の短縮につながる。結果として露光装置のスループット向上につながり装置の生産性が向上する。 The resolution CD of the projection optical system PO is given by Equation 1. Λ of the equation 1 is the wavelength of the light emitted from the light source of the illumination optical system IL, and k1 is a proportionality constant according to the process and the like. On the other hand, the depth of focus DOF is expressed as in Equation 2 using the wavelength λ, the NA of the projection optical system, and the proportionality constant k2. Increasing the NA increases the resolution while decreasing the depth of focus DOF. On the other hand, for patterns that do not require a high resolution CD, the depth of focus DOF can be increased by reducing the NA. By selecting the required NA according to the pattern in this way, the pattern can be exposed more faithfully.

When the NA is reduced, the luminous flux diameter of each optical member is reduced. Therefore, the width W of the slit 5 can be widened without changing the effective diameter of each optical member. By widening the width W of the slit, the integrated light amount during scanning exposure increases, which leads to a reduction in exposure time. As a result, the throughput of the exposure apparatus is improved and the productivity of the apparatus is improved.

FIG. 5 shows the slit shape when the width W of the transmission portion 52 is widened to the width W _b by reducing the NA. The length of the transparent portion 52 at this time in the x direction is defined as X _b . FIG. 6 shows the shape of the effective portion P _b required for the refracting member 6 corresponding to the slit of FIG. As shown in FIG. 6, the size (width) Pw _{b of} the effective portion P _{b in} the y direction becomes larger than the size of the refracting member 6. Therefore, it is necessary to increase the size of the refracting member 6 itself, which may cause a problem that the exposure apparatus becomes large.

In the present embodiment, a slit exchange device (changed portion) for adjusting the slit shape of the luminous flux by exchanging the slit 5 used by the exposure apparatus may be provided. The slit exchange device is controlled by the control unit C, and an optimum slit corresponding to the NA of the projection optical system PO and the required slit width corresponding to the NA is selected from a plurality of prepared slits and arranged in the illumination optical system IL. To do. When the slit width is set to the width W _b by reducing the NA as described above, the slit exchange device has a curvature (first curvature) smaller than the curvature (first curvature) of the slit of FIG. 5 at the width W _b shown in FIG. A slit 5 having a radius of 2) is arranged in the illumination optical system IL. The dotted line in FIG. 7 shows the shape of the slit 5 shown in FIG.

FIG. 8 shows the shape of the effective portion _Pc required for the refracting member 6 when the slit 5 of FIG. 7 is used. The dotted line shows the shape of the effective portion P _b shown in FIG. As shown in FIG. 8, the refracting member 6 covers the entire required effective portion P _c . Therefore, by changing the curvature of the transmitting portion 52 according to the NA of the projection optical system, it is possible to secure the same slit width as the slit width W _b shown in FIG. 7 without changing the size of the refracting member 6. It is possible.

As described above, in the exposure apparatus of the present embodiment, it is necessary to increase the optical member (refractive member 6, etc.) included in the projection optical system PO even if the NA of the projection optical system PO is reduced and the slit width is increased. Absent. Therefore, according to the present embodiment, it is possible to provide an exposure apparatus that is advantageous in terms of the size of the apparatus and the size of the exposure area.

(Second Embodiment)
In the first embodiment, the slit width is widened in the y direction, but in the present embodiment, a case where the slit width is widened in the x direction is considered. FIG. 9 is a diagram showing a slit shape when Xb, which is the slit width of the slit 5 shown in FIG. 5, is expanded to Xc. The dotted line shows the slit shape when the slit width is widened to Xc while keeping the curvature R of the arc of the transmission portion 52 in FIG. The solid line shows the slit shape when the curvature is smaller than the curvature R. As shown in FIG. 9, in the case of the curvature R, the shape of the transmission portion 52 protrudes from the slit 5, and there is an increased need to increase the size of the refraction member 6 and the effective portion. On the other hand, when the curvature is made smaller than R, the transmission portion 52 fits in the slit 5, and it is not necessary to increase the refraction member 6. The same effect as that of the first embodiment can be obtained by this embodiment as well.

In the above embodiment, the slit shape of the light beam of the exposure light that exposes the substrate 3 is adjusted by the slit exchange device, but it may be adjusted by manually exchanging the slits. Alternatively, adjustment may be made by changing the shape of the slit already arranged by the slit shape variable mechanism (adjustment unit) as shown in FIG. Alternatively, the slit shape may be changed and adjusted by using these in combination.

The slit shape variable mechanism includes, for example, a drive control unit 13, a drive unit 14, and a blade 15. The drive control unit 13 includes, for example, a motor, and moves the drive unit 14 forward and backward in the y direction. The blade 15 is made of a sheet metal or the like that can be deformed by applying a force by the drive unit 14. The slit shape variable mechanism is controlled by the control unit C. The control unit C determines the target shape (width and curvature) of the slit corresponding to the NA of the projection optical system, drives the drive unit 14 based on the determined shape, and deforms the blade 15. The deformed shape is measured by a measurement unit (not shown), and the control unit C determines whether or not the measurement result is the target shape. If the target shape is reached, the drive is terminated, and if the target shape is not reached, the drive is continued. The slit shape variable mechanism may further include a drive unit 14 capable of advancing and retreating in the x direction.

11A and 11B are views showing an example of the configuration of the diaphragm 12. The diaphragm 12 shown in FIGS. 11A and 11B is composed of two members 16 and 17 that are movable so as to be separated from each other in the z direction (FIG. 11B), and the two members 16 and 17 are formed. When they are in contact with each other (FIG. 11 (A)), the member has a circular opening. The movement of the two members 16 and 17 is controlled by the control unit C, and the NA is adjusted by the size of the opening.

(Embodiment relating to article manufacturing method)
The method for manufacturing an article according to the present embodiment is suitable for producing an article such as a microdevice such as a semiconductor device or an element having a fine structure. In the method for manufacturing an article of the present embodiment, a step of forming a latent image pattern on a photosensitive agent applied to a substrate by using the above-mentioned exposure apparatus (a step of exposing the substrate) and a step of forming a latent image pattern in such a step are formed. Includes the process of developing the substrate. In addition, such manufacturing methods include other well-known steps such as oxidation, film formation, vapor deposition, doping, flattening, etching, resist stripping, dicing, bonding, packaging and the like. The method for producing an article of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

(Other embodiments)
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

1 Mask 2 Mask Stage 3 Board 4 Board Stage 5 Slit IL Illumination Optical System PO Projection Optical System PO
C control unit

Claims (14)

Illumination optics that illuminate the mask and include slits with openings that shape the light.
It has a projection optical system that projects an image of the mask illuminated by light from the illumination optical system onto a substrate.
An exposure apparatus that exposes a substrate while changing the relative position between the mask and the substrate in a predetermined direction.
An exposure apparatus characterized in that the curvature of a curve defining the aperture is changed according to the NA of the projection optical system. The exposure apparatus according to claim 1, further comprising a changing portion for changing the curvature of the curve defining the opening. The exposure apparatus according to claim 2, wherein the changing portion changes the curvature of the curve defining the opening by applying a force to the slit. The modified portion is characterized in that the slit is exchanged from a first slit having a first curvature to a second slit having a second curvature different from the first curvature. The exposure apparatus according to claim 2. The exposure apparatus according to claim 4, wherein the width of the opening of the second slit in the predetermined direction is different from the width of the opening of the first slit in the predetermined direction. The exposure apparatus according to claim 5, wherein the changing unit changes the width in the predetermined direction. The exposure apparatus according to any one of claims 1 to 6, wherein the predetermined direction is a direction orthogonal to the optical axis of the projection optical system. The exposure apparatus according to any one of claims 1 to 7, wherein the curve is an arc. A claim that the curvature of the curve when the NA of the projection optical system is the first NA is larger than the curvature of the curve when the NA of the projection optical system is the second NA smaller than the first NA. The exposure apparatus according to any one of 1 to 8. The exposure apparatus according to any one of claims 1 to 9, wherein the aperture has an arcuate shape for avoiding the influence of defocus due to aberration of the projection optical system. The projection optical system includes a first reflecting portion that reflects arc-shaped light incident through the opening, a first concave mirror that reflects the reflected light of the first reflecting portion, and the first concave mirror. It is characterized by having a convex mirror that reflects the reflected light, a second concave mirror that reflects the light reflected by the convex mirror, and a second reflector that reflects the light reflected by the second concave mirror. The exposure apparatus according to any one of claims 1 to 10. An illumination optical system that illuminates a mask and includes a slit having an opening for shaping light, and a projection optical system that projects an image of the mask illuminated by light from the illumination optical system onto a substrate. It is an exposure method for exposing the substrate by using.
A step of changing the curvature of the curve defining the aperture so that the curvature is determined based on the NA of the projection optical system.
An exposure method comprising the step of exposing the substrate with light that has passed through the aperture. A claim, wherein the curvature of the curve when the NA of the projection optical system is the first NA is larger than the curvature of the curve when the NA of the projection optical system is the second NA smaller than the first NA. The exposure method according to 12. A step of forming a pattern on a substrate by using the exposure apparatus according to any one of claims 1 to 11 .
A method for producing an article, which comprises a step of processing the substrate on which the pattern is formed in the step.

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