JP3481006B2 - Rotary coating device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coater for uniformly applying a liquid to a substrate used in the manufacturing process of semiconductors, liquid crystal display devices, optical disks and the like by utilizing centrifugal force. In particular, the present invention relates to a spin coating device for high precision coating.

[0002]

2. Description of the Related Art A conventional spin coating apparatus has a structure shown in FIG. 3, in which a substrate 1 is a silicon wafer,
It has a disk shape with a part cut off. Substrate 1 is
It is placed on the substrate pedestal 2 having a similar planar shape. The substrate 1 is not limited to this shape, and may be a true circle, a circle having a hole in the center, a square, a rectangle, or a polygonal plate. In these cases, the substrate pedestal 2 has the same planar shape as the substrate 1. The substrate pedestal 2 has an integral structure with the spin shaft 3, and is held by a bearing case 5 via a bearing 4. A shaft coupling 6 is attached to the lower end of the spin shaft 3, and a spin drive motor 7
Is connected to the output shaft of.

The lower portion of the spin shaft 3 penetrates the inside of the cleaning liquid supply member 11 via two annular seal rings 10. A cleaning liquid pipe 13 is connected to the cleaning liquid supply member 11 via a pipe joint 12. This cleaning liquid supply member 11
Can be arranged above the spin shaft 3, which is easier to manufacture, but in that case, heat generated due to the sliding of the seal ring 10 and the spin shaft 3 is easily transmitted to the substrate 1, The top coating tends to be disturbed. Therefore, the cleaning liquid supply member 11 is often disposed below the spin shaft 3 in an apparatus that performs highly accurate coating. Further, cooling fins may be formed on the outer surface of the cleaning liquid supply member 11 as needed.

The outer peripheral portion of the upper surface of the substrate pedestal 2 is slightly separated from the substrate 1, and a cleaning liquid outlet 15 is opened in this portion. This is connected to the cleaning liquid passage 16 that penetrates from the inside of the substrate pedestal 2 through the inside of the spin shaft 3 to the inside of the cleaning liquid supply member 11. On the other hand, in the center of the upper surface of the substrate pedestal 2,
A vacuum suction groove 17 is formed to widen the vacuum pressure receiving area to obtain a sufficient substrate holding force, and this is connected to a vacuum exhaust passage 18 inside the spin shaft 3. The vacuum exhaust passage 18 is provided with a labyrinth seal 19 inside the bearing case 5.
A vacuum pipe 21 is connected to this space through a pipe joint 20. A fixed chamber 22 is arranged around the substrate pedestal 2 to collect coating droplets scattered during spin coating.

To explain the operation, first, the substrate 1 is placed on the substrate pedestal 2 and the inside of the vacuum pipe 21, the vacuum exhaust passage 18, and the vacuum suction groove 17 are exposed to atmospheric pressure by the operation of a vacuum source (not shown). The substrate 1 is sucked and fixed on the substrate pedestal 2 by applying a low pressure. After that, the coating liquid is dripped or sprayed onto the substrate 1 by a coating liquid supply mechanism (not shown), and the spin drive motor 7
Is activated and spin coating is performed. Simultaneously with the start of the spin rotation, the cleaning liquid is fed from the cleaning liquid supply source (not shown) into the cavity 11A of the cleaning liquid supply member 11 through the cleaning liquid pipe 13. At this time, the tip of the seal ring 10 comes into close contact with the rotating spin shaft 3 to seal the leakage of the cleaning liquid.
The cleaning liquid passes through the cleaning liquid passage 16 and is sprayed from the cleaning liquid outlet 15 to the outer periphery of the back surface of the substrate 1. This allows
By the spin rotation, it is possible to wash away the coating liquid that goes around to the back surface of the substrate.

[0006]

However, such a conventional spin coating apparatus has the following problems in performing highly accurate coating. First of all, the substrate 1
There is a problem with liquid sealing for introducing a cleaning liquid necessary for washing away the coating liquid that wraps around the back surface of the above into the rotating spin shaft. That is, the temperature rise due to the frictional heat of the contact-type seal ring 10 portion has a bad influence on the coating film, although the installation location is away from the substrate 1. In addition, there is a problem that the peeling pieces of the sliding seal ring 10 are mixed into the cleaning liquid, and the life of the seal ring 10 is shortened, so that liquid leakage easily occurs.

Secondly, there is a problem with gas sealing for introducing the vacuum for fixing the substrate 1 onto the substrate pedestal 2 into the spin shaft which also rotates. When the substrate 1 is fixed on the substrate pedestal 2, a method of mechanically grasping with a pin or a claw without using a vacuum may be considered, but in this case, the coating liquid attached to the grasping tool is applied to the substrate. There is a risk that the surface will be soiled or the coating film in the vicinity of where it is gripped by the gripping tool will rise, which is not suitable for high-precision coating.

Even when a vacuum is used to fix the substrate 1, it is difficult to adopt the contact type seal mechanism for the above reasons. Therefore, in the conventional example of FIG. 3, a non-contact type labyrinth seal 19 is adopted. Labyrinth seal 19
Is a non-contact type seal in which the flow resistance of a fluid having compressibility such as air is extremely increased by repeating rapid expansion and contraction of the gap between the spin shaft 3 and vacuum leakage to a small extent. To be However, if the spin rotation speed is increased to achieve high-precision coating or the atmospheric pressure around the substrate 1 is reduced to suppress the influence of the air flow during the spin rotation,
In order to increase the force for fixing the substrate 1, it is necessary to further increase the degree of vacuum and increase the suction force. In this case, the influence of vacuum leakage from the labyrinth seal 19 becomes large, and a vacuum source having an excessive capacity is required. In addition,
If a magnetic fluid seal that holds a magnetic fluid film with a magnet and seals a relatively rotating portion can be adopted in this portion, it will be effective in solving the above problem, but it will be difficult for the reason described later.

Thirdly, since a mechanism for introducing various fluids such as the cleaning liquid and the suction of air into the rotating portion is indispensable as described above, a spin rotation with almost no runout which is a prerequisite for high precision coating. The problem is that it becomes difficult to manufacture the mechanism. In order to make a spin rotation mechanism with almost no rotation shake, the conditions of concentricity and perpendicularity between the substrate pedestal 2 and the spin shaft 3 are strictly manufactured, and the rigidity of the spin shaft 3 itself is secured. It is important not to make it longer than necessary in order to make it sufficiently thick and to prevent the spin shaft 3 itself from swinging. However, in the case of the conventional example of FIG. 3, since the sliding speed is not excessive in the contact type seal portion and the total clearance area is required to be small in the non-contact seal portion, the spin shaft 3 cannot be made sufficiently thick. Further, the spin shaft 3 becomes long due to the attachment of the seal mechanism. That is, it cannot be denied that the manufacture of the spin shaft 3 has become difficult due to restrictions of various fluid introduction mechanisms. Further, if the magnetic fluid seal is used for the spin shaft 3 having a thickness necessary for obtaining high rotation accuracy, the radius of rotation of the magnetic fluid becomes large, and when the spin rotation speed is high, the flow velocity becomes excessively high. As a result, the heat generated due to the viscosity of the magnetic fluid cannot be ignored, and the film cannot be held by the magnet.

In the present invention, the spin shaft is divided, and the dedicated substrate mounting shaft and the fluid introducing shaft are connected to each other by the shaft coupling and the pipe, so that the general seal mechanism is adopted. It is an object of the present invention to provide a spin coating apparatus which can not only eliminate the problems but also has almost no rotational runout of the substrate portion and can be coated with high precision while being easy to manufacture.

[0012]

In order to solve the above-mentioned problems, a first aspect of the present invention provides a spin coating apparatus, wherein a spin shaft rotates a substrate pedestal on which a substrate to be coated is mounted,
A suction passage for sucking the substrate to be coated and a cleaning liquid pressure for supplying a cleaning liquid for cleaning the back surface of the substrate to be coated
And a fluid introduction shaft portion which extends vertically to the container and has at least one of fluid passages through which the cleaning liquid flows. The spin main shaft portion is connected to the fluid introduction shaft portion through a shaft coupling, and a spin drive device. And a pipe communicating with the suction passage and the fluid passage through at least one fluid seal unit is connected to the fluid introduction shaft.

According to a second aspect of the invention, in order to solve the above-mentioned problems, the fluid introducing shaft portion is divided into a plurality of portions according to the number of fluids to be introduced, and these are connected by a shaft coupling. The spin coating apparatus according to the first aspect of the present invention is characterized in that a pipe is arranged between the shafts so that the introduced fluid is sent to the spin main shaft.

In order to solve the above-mentioned problems, a third aspect of the present invention is such that a shaft coupling for connecting shaft portions divided into spin shafts is flexible so as to absorb eccentricity between the shaft portions and a mounting angle error. The first joint characterized by being a shaft joint, and the pipes arranged between the respective shaft parts are made of a flexible material.
The invention provides the spin coating apparatus according to the invention or the second invention.

[0015]

FIG. 1 is a diagram for explaining a first embodiment of the present invention. First, the configuration will be described. The substrate 1 and the substrate pedestal 2 are the same as in the conventional example shown in FIG. The spin main shaft portion 23 is held by a bearing case 25 via a bearing 24. The cleaning liquid passage 16 extends from a plurality of cleaning outlets 15 formed in the peripheral portion of the substrate pedestal 2 to the center point in the radial direction inward, and gathers at the center of the spin main shaft portion 23 along the central axis line. It extends to the lower end.
Further, the vacuum exhaust passage 18 passes through a position different from the cleaning liquid passage 16 inside the spin main shaft portion 23 and penetrates downward.
A sprocket 26 is attached to the lower side of the spin main shaft portion 23, and the sprocket 26 is connected by a timing belt 28 to a sprocket 27 attached to the output shaft of the spin drive motor 7.

The lower end of the spin main shaft portion 23 is connected to a fluid introduction shaft portion 31 via a shaft coupling 30. The shaft coupling 30 is
An upper member 30a attached to the lower end of the spin spindle 23
And the lower member 3 attached to the upper end of the fluid introducing shaft portion 31.
0b and the intermediate member 30c. Each of these members has a pair of annular elastic members 30d in which a rubber material having a certain thickness or a pin (not shown) extending to the rubber material in order to suppress lateral displacement of the rubber material is combined. Upper member 30a, intermediate member 30c, intermediate member 3
0c and the lower member 30b are fixed to each other to be joined. Therefore, the spin main shaft portion 23 and the fluid introduction shaft portion 31
Even if there is an eccentricity or an attachment angle error between the elastic members 3
It is absorbed by the deformation of 0d, and the rotation of the spin main shaft portion 23 is smoothly transmitted to the fluid introduction shaft portion 31.

The fluid introduction shaft portion 31 penetrates through the two magnetic fluid seal units 32 and enters the cleaning liquid pressure-feeding container 33. In the magnetic fluid seal unit 32, the magnetic material pipe 32a is fixed to the fluid introduction shaft portion 31 via the pair of O-rings 32b, and the gap between them is sealed. Both ends of the magnetic material pipe 32a are rotatably supported by two bearings 32c and attached to the case 32d. A cylindrical permanent magnet 32e is fixed between the two bearings 32c. A ring-shaped inner peripheral portion 32f protruding radially inward from the inner wall surface of the N pole of the permanent magnet 32e and a ring-shaped inner peripheral portion 32g protruding radially inward from the inner wall surface of the S pole form a pointed shape, The magnetic flux is concentrated to create a strong magnetic field. A magnetic fluid 32h is filled in a gap between the inner peripheral portion 32f of the N pole and the inner peripheral portion 32g of the S pole and the magnetic material tube 32a, and the N pole and the S pole are opposed to each other with a slight distance therebetween. 32a and the magnetic fluid 32h form a magnetic circuit. Since the magnetic field holding the magnetic fluid 32h is sufficiently strong, the fluid introduction shaft portion 3
Even if the magnetic fluid 32h flows along with the high speed rotation of 1, the film of the magnetic fluid 32h does not break and maintains airtightness.

The vacuum exhaust passage 34 formed inside the fluid introducing shaft portion 31 penetrates from the fluid introducing shaft portion 31 into the space sandwiched between the two magnetic fluid seal units 32. In this space, a vacuum pipe 21 is provided via a pipe joint 20.
Are connected. The cleaning liquid passage 35 formed along the central axis of the fluid introducing shaft portion 31 penetrates from the upper end to the lower end of the fluid introducing shaft portion 31. In the lower part of the cleaning liquid pressure-feeding container 33, in which the lower end of the fluid introduction shaft 31 enters near the inner bottom,
The cleaning liquid pipe 13 is connected from the outside via the pipe joint 12. Further, an air pipe 37 for supplying air for pressurizing the liquid in the cleaning liquid pressure-feeding container 33 is connected to the upper side thereof via a pipe joint 36 from the outside. Further, a liquid level lower limit sensor 38 is installed near the inner bottom of the cleaning liquid pressure-feeding container 33, and a liquid level upper limit sensor 39 is installed at a position slightly lower than the pipe joint 36. Here, the liquid level lower limit sensor 38 and the liquid level upper limit sensor 39 are both float switches that open and close the electrical contacts by floating and sinking their own float, but other types of sensors may be used.

The pipe joints 12 are arranged at the mouth of the cleaning liquid passage 16 at the lower end of the spin main shaft portion 23 and the mouth of the cleaning liquid passage 35 at the upper end of the fluid introducing shaft portion 31, respectively.
They are connected by a cleaning liquid pipe 40 made of a flexible material such as fluororesin. In addition, the spin spindle 2
Of the vacuum exhaust hole 18 in the lower part of 3 and the fluid introduction shaft portion 3
Piping joints 41 are respectively provided at the ports of the vacuum exhaust holes 34 in the upper part of 1, and they are connected by a vacuum pipe 42 made of a flexible material such as urethane resin.
At this time, the cleaning liquid passage 16, the cleaning liquid passage 35, and the cleaning liquid pipe 40 are normally on the same straight line, but the cleaning liquid passage 16 and the cleaning liquid passage 35 may be eccentric or have an attachment angle error. The cleaning liquid pipe 40 having the property absorbs the deviation of the cleaning liquid passages. Vacuum piping 4
2 supports the support tool 43 in order to resist centrifugal force during spin rotation.
Is supported by the shaft coupling 30.

Next, the operation will be described. Substrate pedestal 2 of substrate 1
The adsorption and fixation to the substrate is the same as in the conventional example shown in FIG. When the spin drive motor 7 starts to operate, its rotational force is transmitted to the spin main shaft portion 23 through the sprocket 27, the timing belt 28 and the sprocket 26, and causes the spin main shaft portion 23 to rotate. The rotation of the spin main shaft portion 23 depends on the rotation of the shaft coupling 30.
Is transmitted to the fluid introduction shaft portion 31 through and is rotated at the same rotation speed. At this time, the vacuum pipe 42 also rotates together. As described above, since the spin main shaft portion 23 is rotationally driven at a position separated from the substrate pedestal 2 by the minimum necessary limit, mechanical shake due to the length of the spin axis can be minimized,
Therefore, the rotation accuracy of the substrate pedestal 2 can be improved.

By the spin rotation as described above, the cleaning liquid is blown out in order to wash away the coating liquid that wraps around the back surface of the substrate 1. In the cleaning liquid pressure-feeding container 33,
The cleaning liquid is put in advance to a level between the liquid level lower limit sensor 38 and the liquid level upper limit sensor 39, and at the same time as the spin rotation starts, the supply of the cleaning liquid from the cleaning liquid supply source (not shown) from the cleaning liquid pipe 13 is started, and the air (not shown) From the source, the same pressure as the cleaning liquid supply pressure is applied through the air pipe 37. Thereby, the cleaning liquid can be blown out from the plurality of cleaning liquid outlets 15 through the cleaning liquid pipe 40, the cleaning liquid passage 35, and the cleaning liquid passage 16 without changing the cleaning liquid level in the cleaning liquid pressure-feeding container 33. Further, even if the fluid introduction shaft portion 31 rotates as the spin main shaft portion 23 rotates, since the portion immersed in the cleaning liquid has a small diameter, the rotation hardly disturbs the cleaning liquid surface, and the cleaning liquid is not spoiled.

Next, the operation and structural advantages of this embodiment will be described. First, since the spin main shaft portion 23 can determine the size and shape of each portion irrespective of the introduction of various fluids, the spin main shaft portion 23 is thick enough to ensure the rigidity necessary for smooth rotation, and can be manufactured without sway. It can be of any suitable length. As a result, it is possible to easily manufacture a spin rotating mechanism having the same precision as the conventional example, and it is also possible to make a spin rotating mechanism having a higher precision than the conventional example.

Secondly, since the fluid introducing shaft portion 31 has a size capable of forming the vacuum exhaust passage 34 and the cleaning liquid passage 35, it can have a sufficiently small diameter, and even when the spin main shaft portion 23 rotates at a high speed. Since the flow velocity of the magnetic fluid 32h portion in the magnetic fluid seal unit 32 can be suppressed low, the magnetic fluid seal unit 32 can be used without impairing the sealing property. Since this makes it possible to almost completely eliminate vacuum leakage, a vacuum of lower pressure can be introduced even if a vacuum source having a small capacity is used, and the fixing force of the substrate 1 can be strengthened. Therefore, the spin rotation speed can be increased to perform highly accurate coating, or the atmospheric pressure around the substrate 1 can be lowered to sufficiently suppress the influence of the air flow during the spin rotation.

Thirdly, the fluid introducing shaft portion 31 may be manufactured with a precision not so high that the airtightness of the mounting portion of the magnetic fluid seal unit 32 is not broken, and the spin main shaft portion 2
Even if there is a slight eccentricity or a mounting angle error at the time of connection with 3, the shaft coupling 30 can absorb it, so that the fluid introduction part can be easily manufactured.

FIG. 2 is a view for explaining the second embodiment of the present invention, in which the atmosphere around the substrate is closed to reduce the atmospheric pressure, the air flow during spin rotation is suppressed, and the coating film is prevented from being disturbed. It is the one. A rotating cup 44 is provided in the fixed chamber 22 so as to include the substrate pedestal 2, and a closed space is formed around the substrate 1 together with a cup cover 45 mounted on the fixed cup 22. An exhaust passage 46 is formed in the lower portion of the substrate pedestal 2, and this exhaust passage 46 passes through the substrate pedestal 2 and spin main shaft portion 47.
Penetrate to the bottom of.

Three magnetic fluid seal units 32, through which the fluid introducing shaft portion 48 penetrates, are provided. Similar to the embodiment of FIG. 1, the fluid introduction shaft portion 48 is formed with a vacuum exhaust passage 34 and a cleaning liquid passage 35 for adsorbing the substrate 1. In addition to this, the exhaust passage is provided through a vacuum pipe 42 ′. An exhaust passage 49 connected to 46 is formed. A vacuum exhaust passage 34 penetrates the space sandwiched between the pair of first and second magnetic fluid seal units 32 from above. On the other hand, an exhaust passage 49 penetrates through the space sandwiched by the pair of second and third magnetic fluid seal units 32, and the in-cup exhaust pipe 50 is connected thereto through the pipe joint 20 ′. It The connection between the exhaust passages 46 and 49 is the same as for the vacuum exhaust passages 18 and 34 in the embodiment of FIG. In the case of this embodiment, the pressure at which the substrate 1 is adsorbed on the substrate pedestal 2 is the differential pressure between the pressure of the vacuum system for adsorption and the atmospheric pressure in the rotary cup. Therefore, in order to lower the air pressure in the rotating cup enough to fully exert the airflow suppressing effect during spin rotation, it is necessary to greatly lower the pressure of the vacuum system for adsorption, which cannot be realized with the structure of the conventional example. The structure of this embodiment is required.

In the above embodiments, the single fluid introducing shaft has been described. However, for the convenience of manufacturing the fluid introducing shaft and the like, a plurality of short fluid introducing shafts are used and a space between them is used. You may connect a shaft coupling. Further, the vacuum piping may pass through the inside of the shaft coupling, if necessary. Furthermore, since it is possible to increase the dimension of the fluid introduction shaft portion, it is possible to use a labyrinth seal having a longer seal width and improved sealability than before. Even if the bearing portion of the seal member generates heat due to friction due to the rotation of the spin main shaft portion 23, the distance between the heat generating portion and the substrate pedestal 2 is longer than before, and the rotating shaft coupling 30 is Since it functions as a good heat radiator, the heat does not substantially affect the substrate 1 on the substrate pedestal 2. These allow the use of a contact-type sealing mechanism in some cases, and widen the selection of the sealing method.

[0028]

EFFECTS OF THE INVENTION Since the present invention has the characteristics as described above, a high-accuracy spin rotating mechanism for performing high-accuracy coating, a vacuum for adsorbing a substrate, a cleaning liquid for cleaning the back surface of the substrate, etc. It is possible to obtain a spin coater in which the mechanism for introducing various fluids required for coating of the above into the rotating part can be easily compatible.

[Brief description of drawings]

FIG. 1 is a view showing a structure showing an embodiment of a spin coating apparatus according to the present invention.

FIG. 2 is a view showing a structure showing a second embodiment of the spin coating apparatus according to the present invention.

FIG. 3 is a diagram showing an example of a conventional spin coating apparatus.

[Explanation of Codes] 1 ... Substrate 2 ... Substrate pedestal 3
… Spin shaft 4… Bearing 5… Bearing case 6
... Shaft joint 7 ... Spin drive motor 10 ... Seal ring 11 ... Cleaning liquid supply member 1
2 ... Piping joint 13 ... Washing liquid piping 15 ... Washing liquid outlet 1
6 ... Cleaning liquid passage 17 ... Vacuum adsorption groove 18 ... Vacuum exhaust passage 1
9 ... Labyrinth seal 20, 20 '... Piping joint 21 ... Vacuum piping 2
2 ... Fixed chamber 23 ... Spin spindle 24 ... Bearing 2
5 ... Bearing case 26 ... Sprocket 27 ... Sprocket 2
8 ... Timing belt 30 ... Shaft coupling 30a ... Upper member 30b ... Lower member 3
0c ... Intermediate member 30d ... Elastic member 31 ... Fluid introduction shaft part 32 ... Magnetic fluid seal unit 32a ... Magnetic material pipe 32b ... O ring 3
2c ... Bearing 32d ... Case 32e ... Permanent magnet 3
2f ... Inner peripheral part of N pole 32g ... Inner peripheral part of S pole 32h ... Magnetic fluid 33 ... Cleaning liquid pressure feed container 34 ... Vacuum exhaust passage 3
5 ... Cleaning liquid passage 36 ... Piping joint 37 ... Air piping 3
8 ... Liquid level lower limit sensor 39 ... Liquid level upper limit sensor 40 ... Cleaning liquid piping 4
1 ... Piping joint 42, 42 '... Vacuum piping 43 ... Supporting tool 4
4 ... Rotating cup 45 ... Cup cover 46 ... Exhaust passage 4
7 ... Spin main shaft portion 48 ... Fluid introduction shaft portion 49 ... Exhaust passage 5
0 ... Exhaust pipe in cup

Claims (3)

(57) [Claims] 1. A spin main shaft part for rotating a substrate pedestal on which a substrate to be coated is mounted, a suction passage for adsorbing the substrate to be coated, and a back surface of the substrate to be coated are cleaned. Cleaning liquid pressure supply container for supplying cleaning liquid for
And a fluid introduction shaft portion having at least one of fluid passages for vertically flowing the cleaning liquid , wherein the spin main shaft portion is connected to the fluid introduction shaft portion through a shaft coupling, and a spin drive device is provided. The suction passage is connected to the fluid introduction shaft through one or more fluid seal units,
A spin coater characterized in that a pipe communicating with the fluid passage is connected. 2. The fluid introducing shaft portion is divided into a plurality according to the number of fluids to be introduced, and these are connected by a shaft joint, and the introduced fluid is sent to the spin main shaft portion. The spin coater according to claim 1, wherein the pipe is arranged between the shaft portions. 3. A shaft joint for connecting shaft parts divided into spin shafts is a flexible shaft joint capable of absorbing an eccentricity between the shaft parts or a mounting angle error, and is arranged between the shaft parts. The spin coater according to claim 1 or 2, wherein the pipe provided is made of a flexible material.