JP5609089B2 - Photomask cleaning apparatus and method - Google Patents

Description

  The present invention relates to a substrate cleaning apparatus used for a substrate for a liquid crystal display device, a semiconductor substrate, a photomask substrate, an optical disk substrate, and the like, and a cleaning method using the same.

  The color filter used in the color liquid crystal display panel is formed on a transparent substrate made of a glass substrate through a photolithography process in which a black matrix, a red filter, a green filter, and a blue filter are applied, exposed, and developed, respectively. .

In the exposure step, as shown in FIG. 1, a predetermined portion is cured and formed by exposing a necessary portion using a photomask.
First, as shown in FIG. 1A, a photosensitive resin layer (102) is applied on a glass substrate (101) and exposed to exposure light (103) through a photomask (1) for photosensitivity. The predetermined portion (104) of the conductive resin is cured. Next, as shown in FIG. 1B, a resin layer for the color filter is formed on the substrate through a development process for dissolving and removing the photosensitive resin other than the cured portion (104) of the photosensitive resin layer (102).

  If the photomask (1) used at this time is contaminated by foreign matter such as sublimation or dust, the exposure light does not strike a predetermined place and partial curing is insufficient. Therefore, it is necessary to periodically clean the photomask in order to prevent this.

In periodic cleaning of the photomask, a cleaning apparatus including a transfer unit (105), a spin cleaning unit (106), and an inspection unit (107) as shown in FIG. 2 is often used.
In the spin cleaning unit (106), the substrate (108) is spun and simultaneously cleaned by the brush (109). The cleaning brush (mounted on the movable arm that sweeps on the mask at a constant angular velocity) 109) changes the position at a constant speed to uniformly brush the entire surface of the photomask (108), retract the brush (109), and dry the photomask (108) by spinning at a high speed. A technique and an apparatus are common (Patent Document 1, Patent Document 2).

Usually, in such a brush-type substrate cleaning apparatus, the substrate is rotated in a horizontal posture, and the cleaning brush is moved from the central portion of the substrate surface to the outer peripheral portion while supplying the cleaning liquid from the nozzle onto the substrate.
At this time, the cleaning brush is moved within a cleaning range of the rotating substrate at a predetermined constant speed. However, the circumferential speed of the rotating substrate increases from the center to the outer periphery. Therefore, when the cleaning brush moves on the surface of the substrate at a constant speed, the degree of cleaning differs between the central portion and the outer peripheral portion of the substrate surface, and the surface of the substrate cannot be cleaned uniformly.

  In Patent Document 1, in order to uniformly process the surface of the rotating substrate, the range from the central portion to the outer peripheral portion on the surface of the rotating substrate or from one outer peripheral portion to the central portion in order to uniformly process the surface of the rotating substrate. In a rotary substrate processing apparatus for processing the surface of a substrate by moving the cleaning brush to the range of the other outer peripheral portion, an apparatus provided with control means for variably controlling the moving speed of the cleaning brush has been proposed.

For example, when the moving speed of the cleaning brush is decreased from the central part of the substrate toward the outer peripheral part by the control means, the peripheral speed of the rotating substrate is increased from the central part of the substrate toward the outer peripheral part. By reducing the moving speed of the cleaning brush from the center to the outer periphery of the substrate, the processing time per unit area of the substrate surface by the cleaning brush can be made equal in the plane of the substrate.

  In Patent Document 2, an arm to which a cleaning brush that applies a physical force to the surface of the substrate is attached while rotating the substrate, which is an object to be cleaned, at a predetermined speed is scanned a plurality of times within a predetermined range on the substrate. The substrate cleaning method removes the deposits on the substrate surface by physical force, and the substrate cleaning method increases the number of times the physical force is applied to the outer peripheral portion rather than the vicinity of the central portion of the substrate. There has been proposed a substrate cleaning method in which the number of cleaning brushes for scanning on the substrate is increased with respect to the outer periphery rather than the vicinity of the center of the substrate, and the action of physical force is further increased from the vicinity of the center of the substrate. In addition, a cleaning method having a larger outer peripheral portion has been proposed.

  In recent years, with the increase in size of substrates, the size of photomasks has also increased, and there is a problem that the photomask will be bent by gravity when rotating and holding the edge of the photomask in the spin section of the cleaning process. It has occurred. If it is only to reduce the amount of bending, it is sufficient to increase the thickness of the photomask, but considering that new problems such as increased cost, increased weight, and difficulty in simple transportation will occur. Actually difficult.

  In the method proposed in Patent Document 1 or Patent Document 2, in order to uniformize the degree of cleaning of the central portion and the outer peripheral portion of the substrate to be cleaned (photomask), the substrate is rotated at a constant speed. Basically, the cleaning time per area on the substrate is made uniform by changing the cleaning speed of the cleaning brush near the center of the substrate and the outer periphery of the substrate, or by changing the number of cleaning brushes. Therefore, when the physical force of the cleaning brush on the substrate surface is considered to be constant, for example, a substrate having a size that hardly causes the substrate to be bent seems to be effective.

  One of the problems in applying the conventional technology to a large substrate is that the height of the central portion and the outer peripheral portion of the substrate is different due to the bending of the substrate as described above. This means that the surface does not hit with a uniform pressure and a partial cleaning failure occurs.

  In addition, since the rotation speed of the substrate is different between the central part and the outer peripheral part of the substrate in one constant rotation of the cleaning brush, there is a difference in the brush contact time, resulting in uneven cleaning at the central part and the outer peripheral part. If the brush contact time on the outer periphery is increased in order to clean the entire surface, the cleaning time for the entire photomask will increase and the effect on the production efficiency of the color filter will increase. there were.

Japanese Patent Application Laid-Open No. 11-244796 JP-A-9-148295

  Providing a rotary photomask cleaning apparatus using a cleaning brush that eliminates cleaning unevenness due to bending due to an increase in the size of a photomask, and in particular, provides a uniform cleaning effect in the vicinity of the center and the outer periphery of the substrate.

The invention according to claim 1 of the present invention is a photomask cleaning apparatus, at least, a photo mask holder, a rotation mechanism which rotates while holding the photomask, and the rotation mechanism controller, attached to the arm The photomask holding unit is configured such that the height of the upper surface of the photomask holding unit is the same as the contact surface of the photomask with the rotary brush. And holding the photomask with the side of the photomask sandwiched so that the back surface of the photomask does not contact the rotation mechanism, the rotation mechanism rotates the held photomask, and the rotating brush When the photomask is rotating with respect to the photomask surface and the photomask is rotating, the brush is rotated with respect to the bent photomask. The surface against the uniformly cleaned surface, a photomask cleaning apparatus and performs cleaning.

The invention according to claim 2 of the present invention is a photomask cleaning method using the photomask cleaning apparatus according to claim 1 .

According to the photomask cleaning device of the present invention, the feedback of the pressure of the rotating brush against the photomask surface from the pressure sensor attached to the rotating brush portion and the movable movable angle mechanism of the rotating brush portion can always provide a curved surface. The cleaning surface can be captured by the brush surface, and the cleaning can be performed while the brush surface is always in contact with the cleaning surface at a constant pressure.
Thereby, the problem of the damage | wound which may generate | occur | produce when the contact with respect to the base-material surface of a brush is non-uniform | heterogenous, a washing | cleaning nonuniformity, etc. can be eliminated.

  Further, by making the sweep speed on the photomask of the rotary brush portion variable by the rotary brush position control unit, it is possible to make the brush contact time uniform at the center and the outer periphery of the photomask. It is possible to eliminate cleaning unevenness due to the conversion.

It is the schematic of an example of the exposure process by the photomask of a color filter. (A) shows an exposure process, (b) shows a development process. It is the schematic of an example of the washing | cleaning apparatus of a photomask. It is the schematic of the example of embodiment of the photomask cleaning apparatus of this invention. (A) is a schematic plan view, and (b) is a schematic side view. It is the cross-sectional schematic explaining the relationship between the brush and photomask at the time of a photomask bending. It is the cross-sectional schematic explaining the relationship between the brush and photomask at the time of a photomask bending. (A) shows a case where the photomask is flat, and (b) shows a case where the photomask is bent. It is a schematic diagram when a photomask rotates with a photomask cleaning apparatus.

Embodiments of the photomask cleaning apparatus of the present invention will be described below with reference to the drawings.
FIG. 3 is a schematic view of an embodiment of the photomask cleaning apparatus of the present invention. (A) is a schematic plan view, and (b) is a schematic side view.

  The photomask cleaning apparatus of the present invention is an apparatus for cleaning a photomask, and includes at least a photomask holding unit (2), a photomask rotation mechanism (3) that rotates while holding the photomask, and a rotation mechanism control unit. The photomask cleaning device includes (4), a rotating brush portion (5) attached to the arm (9), and a rotating brush position control portion (6).

  The photomask (1), which is the substrate to be cleaned, is held by the photomask holder (2). The photomask holding portion (2) has a structure in which the photomask (1) is sandwiched between the end portions, and has a mechanism in which the holding portion does not contact the front and back surfaces of the photomask.

  As shown in FIG. 3B, the thickness of the end portion of the photomask holding part (2) may be the same as or thicker than that of the photomask, but the contact surface with the rotating brush part (5) (shown in the figure). Jumping out from the upper surface) is not preferable because it may come into contact with the rotating brush portion during cleaning and be damaged.

  The rotating brush part (5) is held by the rotating brush position control part (6) via the arm (9). Further, the rotating brush portion (5) can be swept in an arc shape around the rotating brush position control portion (6), and further, the rotating brush portion (5) can be rotated by itself. Yes.

  A pressure sensor (8) is installed on the attachment part of the rotating brush part (5) to the arm (9), and the rotating brush position control part (6) controls the photomask substrate direction, that is, the Z-axis direction (the bottom of the figure). The pressing force of the rotating brush portion (5) against the substrate to be cleaned (1) is controlled by an arbitrarily set pressure value and feedback from the pressure sensor (8). It has a mechanism.

Here, the pressure sensor (8) is attached to the attachment part of the rotating brush part (5) to the arm (9). However, since the purpose is to determine the pressing pressure of the rotating brush part, the attachment position is particularly this part. It is not necessary to limit to.
Although not shown, it is desirable that the rotating brush portion (5) be supplied with a cleaning agent necessary for cleaning, a pure water required for washing, or the like as needed. These supplies can be supplied by another mechanism.

  In a state where the photomask (1) is held from the end face by the photomask holder (2), the photomask rotation mechanism (3) rotates to rotate the photomask. The rotary brush position control unit (6) controls the arm (9) to press the rotary brush unit (5) so that the rotary brush unit (5) is pushed into the surface of the photomask (1) by a preset pressure.

In this state, the arm (9) is swung to the left and right to bring the rotating brush portion (5) into contact with the surface of the photomask (1), thereby cleaning the entire photomask.
At this time, if the arm (9) is merely moved by a swing motion, that is, at a constant angular velocity, the peripheral time of the photomask is slow at the center of the photomask (1), so the contact time with the rotating brush (5) is Although it becomes longer, since the peripheral speed of the photomask increases at the outer peripheral portion, the contact time with the rotating brush portion (5) becomes shorter than that at the central portion.

  If the arm swing motion is performed at a constant speed in this manner, the central portion can be cleaned, but cleaning may be uneven on the inside and outside of the photomask, such that the outer peripheral portion is insufficiently cleaned.

  The photomask cleaning apparatus of the present invention has a mechanism that can change the swing speed (angular speed) of the arm (9). FIG. 6 is an explanatory diagram showing the relationship between the position of the brush on the photomask and the angular speed of arm movement. As described above, the swing speed (angular velocity) is increased in the cleaning range of the central portion, and is decreased in the outer peripheral portion, so that the time during which the photomask is in contact with the brush is equalized, thereby performing uniform and efficient cleaning. It becomes possible.

  FIG. 6A shows a schematic plan view during cleaning for this explanation, and FIG. 6B shows a distance (r from the rotation center of the photomask of the rotating brush portion (5) when the photomask is rotated. An example of angular velocity (ω) corresponding to) is shown.

  By adopting a mechanism in which the swing speed (angular speed) of the arm (9) can be varied in this way, not only tracking with a pre-programmed swing speed with respect to the radius (r) but also a swing speed (angular speed) at a desired arbitrary radius portion. ) Can be changed, the part of the photomask (1) can be intensively cleaned as necessary, for example, when part of the photomask (1) is particularly dirty.

  As the size of the substrate (photomask) increases, the deflection of the photomask increases when the photomask is held by support by being sandwiched on the side of the photomask. This is schematically shown in FIG.

  As shown in FIG. 4, when the photomask (1) is held between the photomask holding portions on both end faces, the height direction of the contact surface (lower surface in the figure) of the rotating brush portion (5) The position of is in contact with the cleaning surface at the outer periphery of the photomask (1) but is separated at the center. On the other hand, if the height of the rotating brush portion (5) is adjusted at the center of the photomask, the amount of pushing increases at the outer periphery, which may damage the photomask.

In the photomask cleaning device of the present invention, the pressure sensor (8) is installed in the rotating brush portion (5), and the preset pressure value and the feedback value from the pressure sensor (8) are kept constant, Pressing and releasing in the Z-axis direction are performed by an operation mechanism in the Z-axis direction provided in the rotary brush position control unit (6).
As a result, it is possible to clean the entire surface from the center to the outer periphery of the mask in a uniform state while suppressing fluctuations in pressure at the time of contact of the rotating brush portion (5) caused by bending of the photomask (1).

FIG. 5 schematically shows how the brush portion and the substrate (photomask) contact each other (angle) when bent.
FIG. 5A is a schematic cross-sectional view showing a state of contact of the rotating brush portion (5) with the surface to be cleaned of the photomask when the photomask (1) is placed horizontally without being bent.

  The rotation axis (10) of the rotating brush portion (5) rotated by the brush portion rotating mechanism (7) is perpendicular to the surface of the photomask (1), and the rotating brush is rotated even when the rotating brush is rotating. The surface of (5) uniformly hits the surface to be cleaned.

  On the other hand, FIG. 5B shows a photomask (for example, the outer peripheral side of the photomask in FIG. 4) in a region inclined from the horizontal when the photomask (1) is placed in a bent state. It is the cross-sectional schematic which showed the state of the contact of the rotating brush part (5) with respect to the surface to be cleaned of 1).

  In the figure on the left side of FIG. 5 (b), the rotating shaft (10) of the rotating brush part (5) is fixed so as to be perpendicular to the horizontal surface of the photomask (1), and is inclined from the horizontal. Therefore, only the corner portion of the surface of the rotating brush (5) hits the surface to be cleaned, so that uniform cleaning cannot be performed.

On the other hand, in the photomask cleaning apparatus of the present invention shown in the diagram on the right side of FIG.
Since the angle between the rotating brush portion (5) and the mounting portion of the arm is freely movable, the rotating shaft (10) follows the inclined surface of the photomask (1) and is always vertical. Can move. As a result, even with respect to the photomask (1) in a deflected state, the front surface of the surface of the rotating brush (5) hits the surface to be cleaned so that uniform cleaning can be performed.

In the photomask cleaning device of the present invention, the rotating brush portion (5) is individually separated by the brush portion rotating mechanism (7) in order to reduce the resistance to the movement of the rotating brush portion (5) following the surface to be cleaned. A mechanism that rotates independently is adopted.
As a result, the angle between the rotating brush portion (5) and the arm mounting portion can be freely changed without resistance, so that the movement following the inclined surface of the photomask (1) of the rotating shaft (10) can be performed. It is smoother.

  Since the rotating brush part (5) rotates individually, the surface of the photomask (1) is brushed at the time of cleaning, and at the same time, the mounting part of the rotating brush part (5) is freely movable, so it is applied from the arm (9). Even if the force is pushed in the Z-axis direction, the bristles of the rotating brush portion (5) can be prevented from being bent. Furthermore, by rotating the rotating brush portion (5), it is possible to disperse the force and firmly capture the photomask (1) surface with the brush surface. At this time, the brush movable angle only needs to follow the object to be cleaned (in this case, a photomask), and the mechanism is not particularly limited.

  By using the photomask cleaning device of the present invention, even if the substrate is bent by pressing the rotating brush portion in the Z direction (thickness direction of the substrate to be cleaned) by the brush position control portion as described above, The rotating brush portion can be uniformly contacted with each other, and cleaning unevenness can be eliminated.

  In addition, since the swing speed of the arm provided with the rotating brush portion is variable, it is possible to make the brush contact time uniform between the central portion and the outer peripheral portion of the substrate to be cleaned that is rotating, and the swing speed is reduced. Compared to a fixed case, it is possible to select an optimal cleaning time for each point without performing unnecessary cleaning, thereby contributing to elimination of cleaning unevenness and improvement of cleaning efficiency.

  The rotating brush part is equipped with an independent rotational movement, a movable mechanism at the mounting part, and a pressure sensor, so that even if it is a bent photomask, the photomask can be captured on the entire brush surface. Since the brush pressing pressure is also constant, problems such as insufficient cleaning of the bent portion can be solved.

DESCRIPTION OF SYMBOLS 1 ... Photomask 101 ... Glass substrate 102 ... Photosensitive resin layer 103 ... Exposure light 104 ... Curing part 105 ... Transfer part 106 ... Spin washing part 107 ... Inspection part 108 ... Substrate 109 ... Brush 110 ... Transfer and carry-out of a substrate 2 DESCRIPTION OF SYMBOLS ... Photomask holding part 3 ... Photomask rotation mechanism 4 ... Rotation mechanism control part 5 ... Rotation brush part 6 ... Rotation brush position control part 7 ... Brush part rotation mechanism 8 ... Pressure sensor 9 ... Arm 10 ... Brush rotation axis

Claims (2)

A photomask cleaning device, at least,
A photomask holding unit;
A rotation mechanism which rotates while holding the photomask,
A rotation mechanism control unit;
A rotating brush attached to the arm;
A rotating brush position control unit ,
In the photomask holding part, the height of the upper surface of the photomask holding part is the same height as the contact surface of the photomask with the rotating brush, and the back surface of the photomask does not contact the rotating mechanism. Hold the photomask across the side of the photomask like
The rotating mechanism rotates the held photomask,
The rotating brush has a rotation axis perpendicular to the surface of the photomask, and when the photomask is rotating, the surface of the rotating brush is uniformly cleaned with respect to the bent photomask. A photomask cleaning apparatus , wherein the cleaning is performed by pressing against the photomask. A photomask cleaning method using the photomask cleaning apparatus according to claim 1 .