JPH0751611A - Rotary coating method and rotary applicaor for base plate - Google Patents

Abstract

PURPOSE:To sharply reduce the consumption of a coating material compared with the conventional method in the case where the coating liquid is fed onto a substrate and the substrate is rotated to coat the surface of the substrate with the coating liquid in the form of a thin film. CONSTITUTION:A rotating plate 14 which is arranged in parallel to a substrate 1 above the substrate 1 leaving a slight gap and is rotatable around the same vertical axis as the rotating axial center of a substrate 1 is rotated in the opposite direction to the direction of rotation of the substrate 1 in a diffusion flow process where the base plate 1 is rotated at relatively low speed, and then, it is rotated in the same direction as the direction of rotation of the substrate 1 in a throw-off process where the substrate 1 is rotated at high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating liquid such as a photoresist liquid, a polyimide resin, a silica-based film forming material and a dopant material on a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display device and a glass substrate for a photomask. The present invention relates to a rotary coating method for coating a substrate on a surface of a substrate by supplying a coating liquid to the substrate to rotate the substrate, and a rotary coating apparatus for carrying out the method.

[0002]

2. Description of the Related Art After supplying a coating liquid such as a photoresist liquid onto a substrate such as a semiconductor wafer, a glass substrate or a mask substrate, the substrate is rotated around a vertical axis in a horizontal plane to form an extremely thin coating liquid on the surface of the substrate. In the case of forming the coating film, usually, the rotation speed of the substrate is switched to two stages after the coating liquid is supplied onto the substrate. That is, after supplying the coating liquid onto the substrate, first, the substrate is rotated at a relatively low speed, for example, at a rotation speed of about 1,000 rpm, and the coating liquid supplied onto the substrate is diffused and flowed by a centrifugal force to remove the substrate. Spread over the entire surface (diffusion flow process), then rotate the substrate at a high speed, for example, 3,000 rpm to adjust the coating film spread over the entire surface of the substrate to a uniform film thickness and dry. (Shaking-off process).

Here, there are various types of rotary coating devices for substrates. For example, Japanese Patent Publication No. 57-4898
No. 0, Japanese Patent Publication No. 58-4588, Japanese Patent Laid-Open No. 1-1
In Japanese Patent No. 35565, a container or lid is provided integrally with a rotary table so as to enclose a substrate held in a horizontal position on the rotary table and form a closed or closed space. There is disclosed a rotary coating apparatus in which the substrate and the container or the lid are integrally driven to rotate.
The coating apparatus disclosed in these publications spin-coats the coating liquid on the substrate in a state where the substrate is placed in an atmosphere of the coating liquid solvent which is hermetically closed or closed, so that the peripheral portion of the large round substrate is covered. Even when the peripheral speed is high, or the corners of a rectangular substrate, such as the corners that are cut off by wind during rotation, receive more wind than others, evaporation of the solvent component of the coating liquid is accelerated and the viscosity of the coating liquid increases, causing centrifugation. It is intended to prevent the diffusion flow due to the force from being weakened and to suppress the partial increase in the thickness of the coating liquid film to enhance the uniformity of the coating. In addition, the Japanese Patent Publication No. 57-48980
In the publication, the rotating table and the substrate held by the rotating table and the container that surrounds the substrate and forms a closed or closed space can be separately driven, and the rotation speed of the container is determined by the rotation speed of the rotating table. Increase the speed to make the moving speed of the air in the closed space almost equal to the moving speed (peripheral speed) of the substrate held by the rotating table, and to supply the coating liquid onto the substrate, use only the rotating table. There is disclosed an apparatus configuration capable of rotating the container at a low speed to stop the container.

Further, in JP-A-60-143871, a substrate and a spin head are surrounded by a lower cup fixed to a spindle of a spin head for adsorbing and holding the substrate in a horizontal position and an upper cup combined with the lower cup. The lower cup and upper cup are integrated with an appropriate lock pin, etc., and the lower cup and upper cup are driven to rotate by different motors. There is disclosed a rotary type coating device which can be freely selected. According to this coating apparatus, the atmosphere (temperature, humidity, vapor pressure of the resist solvent, etc.) around the substrate is less likely to change, evaporation of the resist solvent is suppressed, and the resist can be applied to a uniform film thickness. .
Further, in Japanese Unexamined Patent Publication No. 4-61955, parallel to the upper surface of a substrate, particularly a rectangular substrate or a large substrate, which is held in a horizontal position on a turntable, a size equal to or larger than the outer shape of the substrate is provided. There is disclosed a rotary type coating device in which an upper rotary plate having a height is provided and the upper rotary plate is rotated integrally with a rotary base. According to this coating device, the air layer in the flat coating processing space formed between the rotary base and the upper rotary plate is rotated together with the rotating base and the upper rotary plate that rotate integrally, and stays within the coating space. Since there is no relative movement of air with respect to the surface of the substrate, the partial film thickness increase due to the increase in the viscosity of the coating liquid due to the partial vaporization acceleration of the coating liquid solvent is eliminated, and uniform thin film coating is possible. It will be possible.

[0005]

By the way, when the coating liquid supplied onto the substrate is diffused and flowed by rotating the substrate to spread it over the entire surface of the substrate, the coating liquid is centrifugally applied in the radial direction of the substrate. Will spread quickly. On the other hand, the coating liquid on the substrate tries to spread in the circumferential direction of the substrate due to the inertial force (the force that the coating liquid tries to stay in place), but the centrifugal force is far more than the inertial force. Since it is large, a large amount of the coating liquid is scattered from the peripheral edge of the substrate to the periphery before the coating liquid spreads in the circumferential direction of the substrate. For this reason,
A large amount of coating liquid is required to spread the coating liquid on the entire surface of the substrate. For example, in order to spread the coating liquid on the entire surface of the semiconductor wafer at a rotation speed of about 1,000 rpm,
It is necessary to supply onto the wafer an amount of the coating liquid that is about 1,000 times the amount of the coating liquid that is desired to be finally spread on the wafer, and a large amount of expensive photoresist coating liquid is wasted. There is a problem that it becomes.

However, all of the above-described conventional rotary coating apparatuses are configured so that the coating liquid can be coated on the entire surface of the substrate in a uniform thickness, but the consumption amount of the coating liquid is reduced. It is not something you can do.

The present invention has been made in view of the above circumstances, and the coating liquid can be spread rapidly in the circumferential direction of the substrate, and the consumption amount of the coating liquid can be remarkably reduced as compared with the conventional case. It is an object of the present invention to provide a spin coating method for a substrate that can be applied, and a spin coating apparatus that can suitably implement the method.

[0008]

According to the rotary coating method of the present invention, the substrate is rotated at a relatively low speed to spread the coating liquid supplied onto the substrate over the entire surface of the substrate, A rotating plate arranged in parallel with the substrate with a slight distance above the substrate is rotated about the same vertical axis as the rotation axis of the substrate and in a direction opposite to the rotation direction of the substrate,
Next, in a shake-off step of rotating the substrate at a high speed to adjust the coating film of the coating liquid spread over the entire surface of the substrate to a uniform film thickness, the rotating plate is moved to the same vertical axis as the rotating shaft center of the substrate. The gist is to rotate the substrate in the same direction as the rotation direction of the substrate. In this case, the rotating plate may be rotated at a speed higher than the rotation speed of the substrate in the initial stage of the shake-off process, and then the rotating plate may be rotated at the same speed as the rotation speed of the substrate.

Further, as a structure of a rotary coating apparatus for carrying out the above method, a substrate rotation holder having a holding means for holding the substrate in a horizontal posture and rotatably supported around a vertical axis in a horizontal plane. A substrate rotation driving means for rotating the substrate rotation holder, and a substrate controlling the substrate rotation driving means for rotating the substrate rotation holder at a relatively low speed for a predetermined time and then at a high speed for a predetermined time. A rotation control means, a means for supplying the coating liquid onto the surface of the substrate held by the substrate rotation holder, and a size equal to or larger than the outer shape of the substrate and held by the substrate rotation holder. A rotary plate that is placed in parallel with the substrate with a slight gap above the substrate and is rotatably supported about the same vertical axis as the rotation axis of the substrate rotation holder, and this rotary plate is driven to rotate. Rotating plate In a device provided with a rotation driving means and a rotation plate rotation control means for controlling the rotation plate rotation driving means, the rotation plate is supported so as to be rotatable forward and backward, and the rotation plate rotation driving means is forward and reverse. The rotation plate can be driven to rotate, and the rotation plate rotation control means causes the rotation plate to rotate in a direction opposite to the rotation direction of the substrate rotation holder when the substrate rotation holder rotates at low speed, and rotates when the substrate rotation holder rotates at high speed. A control program or control sequence for controlling the rotary plate rotation driving means is provided so as to rotate the plate in the same direction as the rotation direction of the substrate rotation holder.

[0010]

According to the above-described rotary coating method, and when the rotary coating apparatus having the above-mentioned structure is used to apply the coating liquid on the surface of the substrate, a slight amount of liquid is applied above the substrate in the diffusion flow process. When the rotating plates arranged with a gap rotate in the direction opposite to the rotating direction of the substrate, the air between the substrate and the rotating plate rotates together with the rotating plate, and the air is opposite to the rotating direction of the substrate. Flow in the circumferential direction of the direction, the force in the circumferential direction due to this air flow acts on the coating liquid supplied onto the substrate, promoting the force that the coating liquid tends to stay in place on the substrate, The coating liquid rapidly diffuses and flows in the circumferential direction of the substrate, and the coating liquid is spread over the entire surface of the substrate in a short time. Next, in the shake-off process,
When the rotating plate rotates in the same direction as the rotating direction of the substrate above the substrate, the air between the substrate and the rotating plate rotates together with the rotating plate, and the relative air flow to the surface of the substrate disappears. Or less. As a result, the evaporation of the solvent in the coating liquid applied to the substrate surface is prevented from being partially promoted, and the partial film thickness increase due to the increase in the viscosity of the coating liquid is eliminated, and A coating film having a uniform film thickness is formed.

Further, when the rotating plate is rotated at the same speed as the rotating speed of the substrate after the rotating plate is rotated at a speed higher than the rotating speed of the substrate in the initial stage of the swing-off process, the rotating plate is rotated. The higher speed rotation forces the air between the substrate and the rotary plate to undergo greater acceleration than when the rotary plate and the substrate are always rotated at the same speed. Therefore, when the rotation speed of the air between the substrate and the rotating plate increases, the air tends to lag behind the substrate due to the inertia of the air itself. As if it does not have a rotation, the substrate rotates with almost no delay in increasing the rotation speed of the substrate. Therefore, when the rotation speed is increased in the initial stage of the shake-off process, that is, until the high-speed rotation required for the shake-off process is reached, the rise time until the flow of air relative to the plate surface disappears becomes shorter, and thereafter, on the substrate surface. Since the film thickness of the coating liquid film is adjusted in the state where there is no air flow, the uniformity of the film thickness of the coating liquid film is further improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show an example of the structure of an apparatus for carrying out the spin coating method according to the present invention.
2 is a perspective view showing a main part of the apparatus, and FIG. 2 is a partially cutaway side view showing a schematic configuration of the entire apparatus.

This rotary coating apparatus includes a substrate rotation holder 10 for holding the substrate 1 in a horizontal posture and rotating about a vertical axis, a substrate rotation driving motor 12 for rotating the substrate rotation holder 10, and this motor. A control device (not shown) for controlling the drive of 12 and a horizontally movable coating liquid supply nozzle (not shown) for supplying a coating liquid such as a photoresist liquid onto the surface of the substrate 1 held by the substrate rotation holder 10. However, the rotating plate 14 is disposed above the substrate rotation holder 10 and is supported so as to be rotatable forward and backward about the same vertical axis as the rotation axis of the substrate rotation holder 10. A rotary plate rotation driving motor 16 for reverse rotation driving, a control device (not shown) for controlling the driving of the motor 16, and a coating liquid that surrounds the side and the lower side of the substrate 1 and is scattered from the substrate 1. The processing liquid recovery cup 18 for recovery is provided.

The substrate rotation holder 10 has a motor at the center of the lower surface.
A plurality of substrate holding members 24 arranged in the circumferential direction along the periphery of the circular rotary table 22 to which 12 rotary drive shafts 20 are fixed and horizontally supported are attached. There is.
The substrate 1 is supported at its outer peripheral edge by a plurality of substrate holding members 24, is supported from the upper surface of the turntable 22 in a horizontal posture, and is rotated integrally with the turntable 22 so as not to idle. Has been The rotating plate 14 is the substrate 1
It is formed in a circular shape having a size equal to or larger than the outer shape of, and is arranged in parallel with the substrate 1 held by the substrate rotation holder 10. In addition, the rotating plate
Reference numeral 14 denotes a lower position, which is a small distance from the substrate 1 held by the substrate rotation holder 10, as shown in FIG.
It is possible to transfer the substrate 1 from the outside of the recovery cup 18 through the upper opening 26 of the recovery cup 18 onto the substrate rotation holder 10 inside thereof and from the top of the substrate rotation holder 10 to the outside of the recovery cup 18. The motor 16 is integrated with the motor 16 between an upper retracted position that enables the coating liquid to be supplied onto the surface of the substrate 1 held by the substrate rotation holder 10 by a coating liquid supply nozzle (not shown). It is supported so as to be able to move up and down so as to be able to reciprocate, and although not shown, an elevating drive mechanism for that is provided. Further, an exhaust pipe 28 and a waste liquid pipe 30 are communicatively connected to the bottom of the treatment liquid recovery cup 18. Further, the rotary drive shaft 20 of the motor 12 is arranged so as to penetrate the central portion of the bottom portion of the recovery cup 18.

Next, a method of applying the coating liquid on the surface of the substrate using the rotary coating apparatus shown in FIGS. 1 and 2 will be described.

First, the rotary plate 14 and the motor 16 are moved to the upper retracted position, the substrate is carried into the recovery cup 18 through the upper opening 26 of the recovery cup 18, and the substrate 1 is placed on the substrate rotation holder 10. And hold it. Next, the coating liquid is supplied onto the surface of the substrate 1 held by the substrate rotation holder 10 from a coating liquid supply nozzle (not shown). When the coating liquid is supplied onto the substrate 1, the rotary plate 14 and the motor 16 are moved to the lower position shown in FIG. 2, and the rotary plate 14 is arranged so that the upper opening 26 of the recovery cup 18 is almost closed. Then, the motor 12 is rotationally driven to rotate the substrate 1 together with the substrate rotation holder 10 in the direction indicated by the arrow A at a low speed, for example, at a rotational speed of about 1,000 rpm, and the motor 16 is rotationally driven to rotate the rotating plate 14. The substrate 1 is rotated in the direction indicated by arrow b, which is opposite to the rotating direction of the substrate 1. As a result, the air between the substrate 1 and the rotating plate 14 rotates together with the rotating plate 14, and the air flows in the circumferential direction opposite to the rotating direction of the substrate 1, and the force in the circumferential direction due to the air flow is generated. Acts on the coating liquid on the substrate 1. In addition to the centrifugal force, the coating liquid on the substrate 1 is subjected to a circumferential force due to the air flow in the direction opposite to the rotation direction of the substrate 1 to rapidly diffuse and flow in that direction, and Can be spread over the entire surface in a short time. In FIG. 1, the substrate 1 and the rotary plate 14 are shown to be largely separated from each other, but the substrate 1 and the rotary plate 14 are separated from each other.
During the rotation of the two, they approach each other as shown in FIG.
They are close to each other with a space of about 0 mm.

When the coating liquid is spread on the entire surface of the substrate 1, the rotation speed of the motor 12 is increased to rotate the substrate 1 at a high speed, for example, a rotation speed of about 3,000 rpm. At the same time, the motor 16 is reversely driven to rotate the rotary plate 14 in the same direction as the rotation direction of the substrate 1 in the direction indicated by the arrow a at a speed once larger than the rotation speed of the substrate 1 and then the rotation speed of the substrate 1. Rotate at the same speed as. As a result, the air between the substrate 1 and the rotary plate 14 rotates together with the rotary plate 14, the air flows in the circumferential direction that is the same direction as the rotation direction of the substrate 1, and the air relative to the surface of the substrate 1 moves. No flow. At that time, by rotating the rotating plate 14 once at a higher speed than the substrate 1,
The air between the substrate 1 and the rotating plate 14 is forced to undergo a larger acceleration than in the case where the rotating plate 14 and the substrate 1 are always rotated at the same speed. Therefore, the air between the substrate 1 and the rotary plate 14 tends to lag behind the substrate 1 due to the inertia of the air itself when the rotation speed increases, but as far as the relationship with the rotation of the substrate 1 is concerned, The substrate 1 rotates with almost no delay in increasing the rotation speed of the substrate 1 as if it has no inertia, so that the air flow relative to the surface of the substrate 1 disappears. The rise time to reach the state is also shortened. As a result, the evaporation of the solvent in the coating liquid applied to the surface of the substrate 1 is prevented from being partially promoted, the partial increase in the film thickness due to the increase in the viscosity of the coating liquid is prevented, and the film is evenly distributed on the substrate surface. A coating liquid film having a uniform film thickness is formed. FIG. 3 shows a time chart in the above series of operations. A solid line I in FIG. 3 shows the change in the rotational speed of the substrate 1 with time, and a broken line II shows the change in the rotational speed of the rotary plate 14 with time. Then, the series of operations of the substrate rotation holder 10 and the rotary plate 14 as described above are controlled by the motor 12, the controller.
16 is controlled by program control or sequence control, respectively.

In the above embodiment, the mechanical chuck type is used as the substrate rotation holder for holding the substrate in the horizontal posture, but a vacuum chuck type may be adopted. The above-described embodiment is of a so-called mechanical chuck type in which the substrate holding member provided on the upper surface of the rotating table holds and rotates the peripheral edge of the substrate, and thus the back surface of the substrate is touched like a vacuum chuck type. And the backside of the substrate is kept clean.
Moreover, since the rotating plate is rotated at a speed higher than the rotation speed of the substrate in the initial stage of the shake-off process, the influence of wind cutting due to the rotation of the substrate holding member is reduced, and the coating is uneven due to the turbulence of the air flow due to the wind cutting. It never becomes. Further, the rotary coating method and apparatus according to the present invention,
Not only round substrates but also rectangular substrates are targeted,
Further, both large substrates and small substrates are targeted. Furthermore, the number of rotations of the substrate and the number of rotations of the rotating plate are
It may be appropriately set depending on properties, size, shape and the like, type of coating liquid, atmospheric conditions and the like.

[0020]

Since the present invention is constructed and operates as described above, the rotary coating method according to the first aspect of the invention and the rotary coating apparatus according to the third aspect of the invention are used. Then, when the coating liquid is applied to the surface of the substrate, the coating liquid can be spread rapidly in the circumferential direction of the substrate in the diffusion flow process, so that the consumption amount of the expensive coating liquid is lower than that of the conventional one. It can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a principal part showing an example of the configuration of an apparatus for carrying out a method of spin coating on a substrate according to the present invention.

FIG. 2 is a partially cutaway side view showing a schematic configuration of the entire apparatus shown in FIG.

FIG. 3 is a time chart showing an example of a series of operations in the method of spin coating on a substrate according to the present invention.

[Explanation of symbols]

 1 substrate 10 substrate rotation holder 12 substrate rotation drive motor 14 rotating plate 16 rotating plate rotation drive motor 18 processing liquid recovery cup

Claims (3)

[Claims] 1. A diffusion flow process of rotating a substrate around a vertical axis in a horizontal plane at a relatively low speed to spread the coating liquid supplied onto the substrate over the entire surface of the substrate, and a substrate around the vertical axis in a horizontal plane. Rotate at high speed to form a coating solution coating on the surface of the substrate by a shake-off process that adjusts the coating solution coating spread over the entire surface of the substrate to a uniform film thickness. In the method, a rotating plate is arranged parallel to the substrate with a slight distance above the substrate, and the rotating plate is rotated about the same vertical axis as the rotating shaft center of the substrate in the diffusion flow step and in the rotating direction of the substrate. To a substrate characterized in that it is rotated in a direction opposite to that of the above, and in the swing-off step, the rotating plate is rotated about the same vertical axis as the rotating shaft center of the substrate and in the same direction as the rotating direction of the substrate. Rotary Application method. 2. The substrate according to claim 1, wherein the rotating plate is rotated at a speed higher than the rotating speed of the substrate in the initial stage of the swing-off process, and then the rotating plate is rotated at the same speed as the rotating speed of the substrate. Method of rotary coating. 3. A substrate rotation holder that has a holding means for holding the substrate in a horizontal position and is rotatably supported about a vertical axis in a horizontal plane, and a substrate rotation driving means for rotating the substrate rotation holder. A substrate rotation control means for controlling the substrate rotation driving means so that the substrate rotation holder is rotated at a relatively low speed for a predetermined time and then at a high speed for a predetermined time; and a substrate held by the substrate rotation holder. Means for supplying the coating liquid onto the surface of the substrate and having a size equal to or larger than the outer shape of the substrate, and parallel to the substrate with a slight gap provided above the substrate held by the substrate rotation holder. A rotary plate that is disposed and rotatably supported about the same vertical axis as the rotary axis of the substrate rotary holder, a rotary plate rotation driving unit that rotationally drives the rotary plate, and a rotary plate rotation driving unit. Rotating plate rotation to control In a rotary coating apparatus for a substrate, which comprises a control means, the rotation plate is supported so as to be capable of forward and reverse rotation, and the rotation plate rotation driving means is capable of forward and reverse rotation drive, and the rotation plate rotation control When the substrate rotation holder is rotated at a low speed, the rotating plate is rotated in a direction opposite to the rotation direction of the substrate rotation holder, and when the substrate rotation holder is rotated at a high speed, the rotation plate is rotated in the rotation direction of the substrate rotation holder. A rotary coating apparatus for a substrate, comprising a control program or control sequence for controlling the rotary plate rotation driving means so as to rotate in the same direction.