JPH0741194B2 - Rotary coating equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rotary coating apparatus used when coating a surface of a flat substrate to be coated with a coating material.

[Prior Art] In the industrial field related to electronic materials, a rotary coating method is widely used as a method for coating a semiconductor substrate with a viscous fluid such as photoresist. When this spin coating method is applied to a viscous fluid that exhibits so-called Newtonian viscous flow, a coating layer of any thickness can be obtained uniformly over the entire surface of the substrate by setting the rotation speed and rotation time. To be In particular, this uniformity is also related to the smoothness of the surface of the coating layer after drying, and it is possible to easily prevent the occurrence of defects in the coating layer due to dust etc. by devising the equipment. This is a unique feature.

The rotary coating method has been used and developed mainly in the field of electronic materials, but recently, even in the field of general coating materials, uniform and defect-free coating layers have been evaluated when evaluating the corrosion resistance and physical properties of coating layers. There has been an increasing demand for the production of the, and as one of the methods, the rotary coating method has begun to be used.

FIG. 1 is a side view for explaining a conventional rotary coating method and apparatus. That is, a uniform coating layer is obtained on the rotary table (102) by dropping the paint (101) on the center of the substrate to be coated and performing rotary coating with a predetermined rotation speed-hour schedule. Also, mechanically, the rotating shaft (10
According to 3), the turntable rotates and the center of rotation and the center of the coated substrate are almost aligned.

The above-mentioned rotary coating method and apparatus are the mainstream of the conventional method, and can be said to be the basis of the rotary coating method and apparatus, but defects in the coating layer due to dust and air bubbles, or irregularities on the substrate to be coated. As a means for solving the uneven distribution of the coating layer associated with the above, Japanese Patent Publication No. 59-41788 and Japanese Patent Publication No. 61-24699.
A rotary coating method and apparatus, which combines the rotation and the revolution shown in Japanese Patent No. 0, has been proposed.

[Problems to be Solved by the Invention] When forming the above-mentioned coating layer, the conventional rotary coating method and apparatus use the theory such as ALFRED G.EMSLIE [ALFRDE G.EMSLIE, F].
RANCIS T.BONNER AND LESLIE G.PECK: JOURNAL OF APPLI
ED PHYSICS VOL.29858 to 862 (1958)], a coating layer of uniform thickness is formed. In paints that show flow,
The coating layer has a distribution in which the thickness varies depending on the distance from the center of rotation. As an example thereof, FIG. 2 shows a paint exhibiting a thixotropic viscous flow.

Uniform coating layer thickness of the above-mentioned non-Newtonian viscous paint coating, prevention of coating layer defects caused by dust and air bubbles, and uneven coating layer thickness due to irregularities on the substrate to be coated. The method and apparatus proposed in Japanese Patent Publication No. 61-246990 is considered effective for the correction of the above. However, such a method and apparatus are intended for application to electronic materials, and are uniform in the general coating field. For application to various coating layers,
It has a surface that cannot be dealt with. The specific problems are as follows.

In the method combining the revolution and the rotation, it is necessary that the rotation speed of the rotation is lower than the rotation speed of the revolution, but the ratio of (rotation speed of revolution) / (revolution speed of revolution) (hereinafter, rotation revolution). If it is applied with a paint exhibiting non-Newtonian viscous flow as in the present invention, the effect of the centrifugal force of rotation is large when the ratio is called). The thickness distribution exhibits a distribution due to the centrifugal force of rotation.

In order to avoid this, it is desirable that the rotation / revolution ratio is about 0.1 or less, preferably about 0.01 or less, and the rotation is performed once or more within the coating time. When an attempt is made to give a motion to the coated substrate by a combination of rotation and revolution by the drive source, there is a limit to the miniaturization of the revolution ratio due to the geometrical positional relationship of the gears or pulleys that transmit the drive.

It is also possible to install a rotation drive source in addition to the revolution drive source as a method of achieving a smaller rotation-revolution ratio. In this case, the centrifugal force generated by the revolution adds to the rotation drive source, It is foreseen that the upper limit of the number will be limited, and that it will cause a failure of the drive source for rotation. Further, when separate drive sources are installed for the rotation and the revolution, it is also a problem that cannot be overlooked that the synchronism between the revolution and the rotation is disturbed.

The second problem raised is the spread of the paint dropped on the substrate to be coated on the substrate. In the method of combining the revolution and the rotation, the driving force for spreading the paint on the substrate to be coated is the centrifugal force due to the revolution, and its center is not on the substrate to be coated. Therefore, the dropped paint cannot spread over the entire surface of the substrate to be coated, resulting in an uncoated portion. In order to avoid this, it is necessary that an excessive amount of paint is dropped and the paint is already supplied to the entire surface of the substrate to be coated before the rotation is started. However, such a measure is not a preferable method because it significantly reduces the yield of the paint. However, in order to efficiently spread the paint on the substrate to be coated, even in the method of combining the rotation and the revolution, the center of centrifugal force is applied in the process of spreading the paint on the substrate to be coated after the paint is dropped. It is desirable to be located in the center of the coated substrate. This means that even in the method of combining the rotation and the revolution, it is necessary to provide a drive system in which the force mainly composed of the centrifugal force of the rotation acts on the paint in the spreading process of the paint located in the initial process of painting. Is characterized by.

The present invention has been made in view of the circumstances as described above, and it is possible to easily obtain a coating layer having a uniform thickness over general coating materials in general, and particularly for coating materials showing non-Newtonian viscous flow. The present invention aims to provide a rotary coating device.

[Means for Solving the Problems] To this end, in the rotary coating apparatus of the present invention, a main shaft (1) rotated by a power source and a revolution member (4) fixed to the main shaft (1). ), First power transmission means (5, 6, 7) for transmitting the rotation of the main shaft (1), and a sub shaft (2) rotated by the first power transmission means (5, 6, 7), Second power transmission means (8, 8) for transmitting the rotation of the sub shaft (2)
9, 10) and the second power transmission means (8, 9, 10) for rotation, and is rotatably arranged around the main shaft (1),
Third power transmission means (11, 11 ') connected to the second power transmission means (10) and fourth power transmission means (12) for transmitting the rotation of the third power transmission means (11, 11'). , 12 ', 13, 1
3 ') and the fourth power transmission means (12, 12', 13, 13 ')
Driven shafts (3, 3 ') rotatably fixed to the revolving member (4) by being rotated by the third power transmission means (11, 11'). A coating container (14, 14 ') fixed to the driven shafts (3, 3'), the first power transmission means (5, 6, 7) of the main shaft (1), and the second power transmission means ( The rotary coating apparatus is characterized in that it is provided with a power disconnecting mechanism (15) between the rotary coating apparatus (8, 9, 10).

In the case of a coating layer obtained by applying a paint showing a non-Newtonian viscous flow to a substrate to be coated by the above means, and obtaining a thickness distribution of the obtained coating layer by a conventional rotary coating method using only rotation as an acting force. It is shown in FIG. From this result, it is clear that the use of the rotary coating apparatus of the present invention makes it possible to obtain a uniform coating layer of a general coating material including a coating material showing non-Newtonian viscous flow.

[Embodiment] An embodiment of the present invention will be described with reference to the longitudinal sectional view shown in FIG.

In FIG. 4, 1 is a main shaft, 2 is a sub shaft, 3, 3 is a driven shaft, 4 is a revolving member, 5, 7, 8, 13, 13 ′ are timing pulleys fixed to the respective shafts, 10, 11, 11 'is a timing pulley rotatably arranged around the main shaft and connected to each other, 6, 9, 12, 12' are timing belts, 14,
14 'is a coating container, 15 is a power connection / disconnection mechanism, 16 and 16' are coating container lids, 17 and 17 'are substrates to be coated, 18, 19, 20, 21, 21'
Is a bearing, and 22 is a part of the casing.

In the rotary coating apparatus having such a structure, the timing pulley (5) is fixed to the main shaft (1), and the timing pulleys (7) and (8) are connected and fixed to both ends of the sub shaft (2). 2) passes through the sleeve and is held by the bearing bearing. Timing pulley (1
0), (11), (11 ') are connected to each other, and the spindle (1)
The bearings are held through the bearings. The timing pulleys (13) and (13 ') are fixed to the lower ends of the driven shafts (3) and (3'). The driven shaft (3) and the driven shaft (3 ') are held by a rotating member (4) fixed to the upper end of the main shaft (1) at bearings in symmetrical positions with respect to the main shaft (1).

The timing belts for power transmission are between the timing pulley (5) and the timing pulley (7), between the timing pulley (8) and the timing pulley (10), between the timing pulley (11) and the timing pulley (13),
Timing pulley (11 ') and timing pulley (1
It is hung between 3 ').

According to the rotary coating apparatus having the drive mechanism having the above configuration,
The main shaft (1) rotates due to the drive of a power source such as a motor,
The rotation is transmitted from the timing pulley (5) fixed to the main shaft (1) to the timing pulley (7) by the timing belt (6), and further through the timing pulley (8) and the timing belt (9). ) Is transmitted to the rotation. The rotation of the timing pulley (10) passes through the timing pulleys (11) and (11 ') connected to the timing pulley (10), and then the timing belt (1
It is transmitted to the timing pulleys (13) and (13 ') by 2) and (12'), respectively. The rotation of the timing pulleys (13), (13 ') is transmitted to the driven shafts (3), (3'), and further, the coating container (14) fixed to the upper portions of the driven shafts (3), (3 '). , (14 ') is rotated. Then, a required amount of paint is dropped on the substrate to be coated mounted in the coating containers (14) and (14 '), and the rotary coating in which the revolution and the rotation are combined is performed based on the drive mechanism described above.

In the above series of rotational drive transmission, the number of teeth of the timing pulley (5) is a, the number of teeth of the timing pulley (7) is b, the number of teeth of the timing pulley (8) is c, the number of teeth of the timing pulley (10). D, timing pulley (1
1), the number of teeth of (11 ') is e, the timing pulley (1
If the number of teeth in 3) and (13 ') is f, then the revolution ratio (R)
{Rotational speed [rotational speed of driven shafts (3) and (3 ')] /
The revolution speed [revolution speed of the main shaft (1)]} is given by the following equation.

R = (ac / bd-1) d / f However, when R> 0, the rotation direction of rotation is the same as the rotation direction of revolution, and when R <0, the rotation direction of rotation is opposite to the rotation direction of revolution. When R = 0, only the revolution is possible.

Therefore, the R value can be set to an arbitrary value by setting five variables a to f as the number of teeth of the timing pulley in consideration of geometrical conditions such as the diameter of the shaft and the distance between the shafts.
As a result, it is possible to meet the requirement that the above-mentioned rotation ratio is 0.1 or less and that the rotation is performed once or more within the coating time, and to obtain a uniform and defect-free coating in a coating showing non-Newtonian viscous flow. The formation of layers can be realized.

The rotary coating device of the present invention uses a single power source to
The present invention is characterized in that the rotation / revolution ratio can be arbitrarily selected, and it is impossible to achieve the above-described rotary motion with a single power source by conventional techniques. Furthermore,
The feature of the single power source is that the revolution and the rotation are excellent in synchronism.

In the rotary coating method of the present invention, the power interrupting mechanism (15) shown in FIG. 4 is installed so that the coating material dripped on the substrate to be coated efficiently spreads over the entire surface of the substrate to be coated. The following coating schedule is implemented by the operation of the power interruption mechanism (15). That is, immediately after the paint is dropped on the substrate to be coated, the driving force of the power source is not transmitted to the rotary disk (4) attached to the upper part of the main shaft by the power interrupting mechanism (15), and the driven shaft (2) and Used for rotation of (2 ') only. Therefore, the rotating containers (14) and (14 ') holding the substrate to be coated only rotate. The rotation process immediately after the dropping of the paint is set within a few seconds, and thereafter, rotary coating is performed by a method that combines the revolution and the rotation for uniform coating film thickness.

In the rotation process in the above coating schedule, the paint dropped on the center of the substrate to be coated spreads out in the surroundings because the center of rotation is also at the center of the substrate to be coated, and even if a relatively small amount of drops is applied, no coating is required. Can be prevented.

Further, in the method in which the rotation and the revolution are combined, when two or more substrates to be coated are coated at the same time, there is a possibility that paint splashes generated during coating may adhere to the coated surface of the substrate to be coated. This obstacle can be avoided by mounting the substrate to be coated in a rotary container with a lid as in the above embodiment.

[Brief description of drawings]

FIG. 1 is a side view showing the basic structure of a conventional rotary coating apparatus, and FIG. 2 is obtained by a conventional rotary coating method.
FIG. 3 is a graph showing an example of the coating thickness distribution of a coating showing non-Newtonian viscous flow, and FIG. 3 is a coating thickness obtained by applying the rotary coating apparatus of the present invention to a coating showing non-Newtonian viscous flow. FIG. 4 is a longitudinal sectional view of a rotary coating apparatus according to an embodiment of the present invention, in which the distribution is compared with that of a conventional rotary coating apparatus. 101: paint, 102: rotary base, 103: rotary shaft, 104: substrate to be coated,
105: motor, 106: thickness of coating layer, 107: distance, 108: center of rotation, 109: thickness distribution of coating layer by conventional rotary coating device, 110: coating layer by rotary coating device of this invention Thickness distribution

Claims (1)

[Claims] 1. A main shaft (1) rotated by a power source, a revolution member (4) fixed to the main shaft (1), and first power transmission means (5, 5) for transmitting the rotation of the main shaft (1). 6,
7), a sub-shaft (2) rotated by the first power transmission means (5, 6, 7), and a second power transmission means (8, 9, 10) transmitting the rotation of the sub-shaft (2). And a third power transmission that is rotated by the second power transmission means (8, 9, 10), is rotatably arranged around the main shaft (1), and is connected to the second power transmission means (10). Means (11, 11 '), fourth power transmission means (12, 12', 13, 13 ') for transmitting the rotation of the third power transmission means (11, 11'), and the fourth power transmission means (12,
12 ', 13, 13') is driven by the driven shaft which is rotated by 12 ', 13, 13'), is arranged symmetrically with respect to the third power transmission means (11, 11 '), and is rotatably fixed to the revolution member (4). (3,
3 '), a coating container (14, 14') fixed to the driven shafts (3, 3 '), the first power transmission means (5, 6, 7) of the main shaft (11), and the first shaft. Two power transmission means (8, 9, 1
A rotary coating device characterized in that a power disconnecting mechanism (15) is provided between the rotary coating device and (0).