JP2000003849A - Resist application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist application device which can form a uniform resist film on a wafer, while keeping the resist consumption minimum. SOLUTION: This device has wafer holding mechanisms 15, 16 which hold a wafer 14 horizontally and rotate the wafer 14, a center nozzle 8, which discharges resist 2 to a center position of the wafer 14 held by the wafer holding mechanisms 15, 16 and a side nozzle 13 which discharge the resist 2 to the wafer 14 held by the wafer holding mechanisms 15, 16 at a position shifted by a specified distance in a wafer radial direction from the wafer central position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resist coating apparatus for forming a resist film on a wafer by a spin method.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for forming a thin resist film on a wafer, a resist is dropped on a wafer, and then the wafer is rotated at a predetermined number of rotations. A spin-type resist coating apparatus (spin coater) for forming a film is known.

FIG. 5 is a schematic diagram of a conventional resist coating apparatus. In the figure, a resist 52 placed in a resist bottle 51 is sucked up by a pump 53 and reaches a coating nozzle 58 via a resist filter 54, a valve 55, a resist pipe 56 and a resist temperature controller 57.
The resist 52 sucked up in this manner is applied to the coating nozzle 5
8 is discharged onto the wafer 59. The wafer 59 is held horizontally by a spin chuck 60 and is rotated by driving a spin motor 61 in this state.

In the resist coating apparatus, a resist 52 is discharged from a coating nozzle 58 to a wafer 59 held horizontally by a spin chuck 60 at the center of the wafer. Thereafter, the resist film is formed on the wafer 59 by rotating the wafer 59 by driving the spin motor 61. This is shown in FIGS. 6 (a) to 6 (d).

First, immediately after the resist 52 is discharged onto the wafer 59 from the application nozzle 58, a core of the resist 52 is formed at the center of the wafer 59 as shown in FIG. Next, when the wafer 59 starts to rotate by the drive of the spin motor 61, the centrifugal force generated by this causes the core of the resist 52 to start to spread greatly as shown in FIG. 6B, and further increases the rotation speed of the wafer 59. Then, as shown in FIG. 6C, the core of the resist 52 collapses, and the resist 52 spreads to the vicinity of the periphery of the wafer 59. Finally, the entire surface of the wafer 59 is coated with the resist 52 as shown in FIG. After that, the wafer 59 is appropriately rotated in order to make the resist film a desired film thickness and to improve the film thickness uniformity on the wafer surface, and a series of processes is completed.

[0006]

The resist 52 placed in the resist bottle 51 contains a volatile solvent (thinner) in order to keep its viscosity low.
After the resist 52 is applied on the wafer 59, the solvent is volatilized to cure the resist film.

However, conventionally, the coating nozzle 58
The resist 52 dropped onto the wafer 59 from the
The solvent volatilizes in the stage of spreading by the centrifugal force due to the rotation of 9, and the resist 52 hardens without the resist 52 spreading over the entire surface of the wafer 59 as shown in, for example, FIGS. 6B and 6C. there were. Further, even when the resist 52 spreads over the entire surface of the wafer 59, coating unevenness occurred at the peripheral portion of the wafer, which is considered to be caused by the curing of the resist 52. Particularly recently, the diameter of the wafer 59 has been increased,
Accompanying this, coating unevenness in the peripheral portion of the wafer becomes remarkable.

As a countermeasure, the discharge amount of the resist 52 from the application nozzle 58 is increased more than necessary, or the resist solvent is applied to the wafer 59 before the resist 52 is applied.
The resist is hardened by delaying the curing time of the resist 52 by applying it on the top. However, in any case, the manufacturing cost is significantly increased, and it cannot be said that it is an advantageous measure. In particular,
In recent years, expensive resists typified by chemically amplified resists have also become widespread, and from this viewpoint, realization of so-called resist saving, which minimizes the amount of resist consumption, has become an urgent task. I have. As a countermeasure other than the above, a processing method in which the wafer is rotated at a high speed during pre-spin to cover the entire surface of the wafer in a short time has been proposed. Invite the problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a resist capable of forming a uniform resist film on a wafer while minimizing the consumption of the resist. An object of the present invention is to provide a coating device.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a resist coating apparatus for forming a resist film on a wafer by dropping a resist on the wafer and rotating the wafer. A wafer holding mechanism for rotating the held wafer, a first application nozzle for discharging a resist to the wafer held at the center position of the wafer, and a wafer held by the wafer holding mechanism. On the other hand, a configuration including a second coating nozzle for discharging a resist at a position shifted by a predetermined distance in the wafer radial direction from the center position of the wafer is adopted.

According to the resist coating apparatus having the above configuration, the resist is discharged to the wafer center position by the first coating nozzle on the wafer held substantially horizontally by the wafer holding mechanism, and the resist is discharged by the second coating nozzle. By discharging the resist at a position shifted by a predetermined distance from the center position of the wafer, the resists discharged from the respective application nozzles are mixed with each other and smoothly spread over the entire surface of the wafer. Further, since the resist is discharged to a position shifted from the center position of the wafer by the second application nozzle, the resist can be spread to the outer peripheral edge of the wafer without being cured.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing one embodiment of a resist coating apparatus according to the present invention. In the illustrated resist coating apparatus, a predetermined amount of resist 2 is put in a resist bottle 1, and two resist supply systems are provided using the resist bottle 1 as a common resist storage source.

One resist supply system comprises a pump 3, a resist filter 4, a valve 5, a resist pipe 6, a resist temperature controller 7, and a coating nozzle 8. On the other hand, the other resist supply system includes a pump 9, a resist filter 10, a valve 11, a resist pipe 12, a resist temperature controller 7, and a coating nozzle 13. Among these, the resist temperature controller 7 is shared by the two resist supply systems.

On the other hand, the wafer 14 to be processed is held horizontally by the spin chuck 15 with its processing surface (pattern forming surface) facing upward. The wafer 1 held by the spin chuck 15
4 is a spin motor 1 connected to a spin chuck 15
6 is rotated by driving.

Further, one of the application nozzles 8, 13 corresponding to the two resist supply systems described above is connected to one of the wafers 14 held by the spin chuck 15.
, Is disposed directly above the wafer center position (rotation center) so as to face the wafer processing surface. The other coating nozzle 13 is positioned directly above the wafer 14 held by the spin chuck 15 at a position shifted from the center position of the wafer by a predetermined distance (described later) in the radial direction of the wafer. It is arranged in the state facing. Hereinafter, for convenience of explanation, one application nozzle 8 is referred to as a “center nozzle” and the other application nozzle 13 is referred to as a “side nozzle”.

In addition, an imaging camera 17 is provided above the spin chuck 15. This imaging camera 17
Captures the state of the resist discharged from the center nozzle 8 onto the wafer 14 as an image, and converts the image to an image signal S
1 is output to the main control unit 18. As the imaging camera 17, for example, a CCD (Charge Coupled D)
evice) A camera is used.

The main control unit 18 captures and analyzes the image signal S1 sent from the imaging camera 17, and sends control signals S2 and S3 derived from the analysis result to the pump control unit 19 and the valve control unit 20, respectively. Output. The pump control unit 19 controls the driving state of the pump 9 according to the control signal S2 sent from the main control unit 18, and the valve control unit 20 controls the valve according to the control signal S3 sent from the main control unit 18. 11 to control the open / close state.

FIG. 2 is a functional block diagram showing the internal configuration of the main control unit 18. Main control unit 18 shown
Is constituted by, for example, a personal computer comprising a CPU (Central Processing Unit) and its peripheral circuits, and its main functional parts are an image storage unit 18a,
Image comparison unit 18b, calculation unit 18c, and control signal output unit 1
8d.

The image storage unit 18a stores in advance image data in which the resist 2 discharged from the center nozzle 8 onto the wafer 14 has spread to a predetermined area when the apparatus is started, for example. The image comparison unit 18b compares the image data S1 captured by the imaging camera 17 with the image data stored in the image storage unit 18a, and provides the comparison result to the calculation unit 18c.

The calculation section 18c calculates the timing of discharging the resist from the side nozzles 13 based on the comparison result of the image comparison section 18b, and gives the calculation result to the control signal output section 18d. The control signal output unit 18d
The control signals S2 and S corresponding to the calculation result in the calculation unit 18c
3 is a pump control unit 19 and a valve control unit 2
0 to operate the pump 9 and the valve 11 via these control units 19 and 20.

Here, if the pump 9 and the valve 11 are operated to discharge the resist 2 only from the side nozzles 13 and rotate the wafer 14, as shown in FIG. It becomes the state coated with. Note that the crosses in the figure indicate the positions of the side nozzles 13 on the wafer 14. Therefore, the center nozzle 8 and the side nozzle 1 in the wafer radial direction
3 (from the center position of the wafer to the side nozzle 13)
When the resist 2 discharged from the center nozzle 8 is spread by the rotation of the wafer 14, the resist 2 is discharged from the side nozzle 13 within a range where the resist 2 can spread smoothly without being cured on the wafer 14. The resist 2 is set so as to satisfy the conditions for dripping.

Although the position of the side nozzle 13 that satisfies the above conditions specifically depends on the diameter of the wafer 14 to be processed, the viscosity of the resist 2, the number of rotations of the wafer 14 during the processing, etc. It may be set at a substantially intermediate position between the wafer and the outer peripheral edge of the wafer or slightly closer to the outer peripheral edge of the wafer.

Next, the operation of the resist processing apparatus having the above configuration will be described. First, the wafer 14 to be processed is held horizontally by the spin chuck 15, and in this state, the resist 2 in the resist bottle 1 is sucked up by driving the pump 3. Resist 2 sucked up
After dust and the like are removed by the resist filter 4, the dust reaches the center nozzle 8 via the resist pipe 6 and the resist temperature controller 7 by opening and closing operation of the valve 5, and is discharged onto the wafer 14 from the center nozzle 8. Thereby, the wafer 14
4A, a core of the resist 2 is formed as shown in FIG.

Subsequently, the rotation of the wafer 14 is started by the driving of the spin motor 16. Then, the core of the resist 2 on the wafer 14 starts to spread radially due to the centrifugal force accompanying the rotation of the wafer 14. Here, as an example, a processing method in which the resist 2 is discharged from the center nozzle 8 onto the wafer 14 and then the wafer 14 is rotated is adopted. And a processing method for discharging the resist 2 from the center nozzle 8 may be adopted.

When the resist 2 begins to spread on the wafer 14 in this manner, the degree of the spread is imaged by the imaging camera 17, and the image data S 1 obtained by this is sent to the main control unit 18.

At this time, the main control unit 18
The image data S1 sent from the imaging camera 17 and the image data previously stored in the image storage unit 18a are compared by the image comparison unit 18b. Then, when the two image data coincide with each other, that is, when the degree of spreading of the resist 2 on the wafer 14 becomes a preset state, the fact is notified to the calculation unit 18c.

In response to this, the arithmetic unit 18c sets a timing at which the comparison unit 18b notifies that the image data coincides as a reference time t, and sets a predetermined time t 'set in advance to the reference time t. By performing the addition, the discharge timing of the resist from the side nozzle 13 is calculated. The predetermined time t 'added here is the time required from when the pump 9 and the valve 11 are operated to when the resist 2 is actually discharged from the side nozzle 13 or the center nozzle 8 and the side nozzle 13 in the wafer radial direction. Is set in advance in consideration of the positional relationship, the viscosity of the resist 2, the number of rotations of the wafer, and the like. Further, the control signal output unit 18d outputs control signals S2 and S3 to the pump control unit 19 and the valve control unit 20, respectively, in accordance with the resist discharge timing calculated by the calculation unit 18c.

When the control signals S2 and S3 are output from the main control unit 18, the control signals S2 and S3 are output.
According to 3, the pump 9 and the valve 11 are driven. As a result, the resist 2 in the resist bottle 1 is pumped by the pump 9
Sucked up by Resist 2 sucked up
After dust and the like are removed by the resist filter 10 in the same manner as described above, the resist pipe 1 is opened and closed by opening and closing the valve 11.
2. After reaching the side nozzle 13 through the resist temperature controller 7,
The liquid is discharged from the side nozzle 13 onto the wafer 14.

Thus, as shown in FIG. 4B, when the resist 2 previously discharged from the center nozzle 8 has spread to some extent on the wafer 14, the resist 2 discharged from the side nozzle 13 It is dropped on the periphery of the wafer. Thereafter, when the resist 2 discharged from the center nozzle 8 further spreads, the resists 2 discharged from both the nozzles 8 and 13 mix as shown in FIG. 4C, and finally, as shown in FIG. As shown in (1), the entire surface of the wafer 14 is coated with the resist 2, and a resist film is formed on the wafer 14. After that, the wafer 14 is appropriately rotated in order to make the resist film a desired film thickness and to improve the film thickness uniformity on the wafer surface, and a series of processes is completed.

As described above, the resist coating apparatus of the present embodiment is provided with two nozzles such as the center nozzle 8 and the side nozzle 13, and uses these two nozzles.
Since the resist is respectively discharged at two positions, that is, the center position of the wafer 14 and a position shifted by a predetermined distance in the wafer radial direction therefrom, the resist hardening phenomenon during the processing can be effectively prevented. Accordingly, the wafer 1 can be discharged without discharging a large amount of the resist 2 unnecessarily.
4 can spread the resist 2 smoothly. Further, since the resist 2 discharged from each of the nozzles 8 and 13 can be efficiently spread on the wafer 14, the amount of resist used per wafer can be minimized. Furthermore, the side nozzle 13
Then, the resist 2 is discharged directly to the peripheral portion of the wafer, and the resist 2 spreads smoothly to the peripheral portion of the wafer, so that coating unevenness at the peripheral portion of the wafer can be prevented.

The extent of spreading of the resist 2 discharged from the center nozzle 8 onto the wafer 14 is imaged by the imaging camera 7, and the image signal S 1 obtained by this is analyzed by the main control unit 18 and processed by the side nozzle 13. Since the configuration for controlling the timing of discharging the resist from the nozzle 2 is adopted, it is possible to discharge the resist 2 from the side nozzle 13 at an appropriate timing at all times.

In the above embodiment, a configuration in which one side nozzle 13 is added in addition to the center nozzle 8 is taken as an example. However, the present invention is not limited to this, and the number of the side nozzles 13 may be reduced. There may be two or more.

Further, in the above-described embodiment, a configuration is employed in which the degree of spreading of the resist 2 on the wafer 14 is directly imaged by the imaging camera 17 and the timing of discharging the resist from the side nozzles 13 is controlled. In addition, for example, the state in which the resist 2 is discharged from the center nozzle 8 is indicated by CC.
Captured by a D camera or the like, and
It is also possible to adopt a configuration in which the degree of spread of the resist 2 is predicted and the timing of discharging the resist from the side nozzles 13 is controlled.

Further, a so-called sequential control method in which the devices are sequentially operated according to a predetermined order is employed, and after a certain time has elapsed from the opening and closing operation of the valve 5, the pump 9 is driven, and then the valve 11 is opened and closed. If a configuration in which the resist 2 is ejected from the side nozzle 13 by operating it is not necessary, an expensive imaging camera 17 and a complicated and large-scale control system are not required, so that the cost of the apparatus is reduced and the apparatus configuration is simplified. Can be achieved. However, in that case, the resist 2 is actually discharged from the side nozzle 13 after the conditions of the resist processing apparatus are determined in advance and the degree of spreading of the resist on the wafer or the pump 9 and the valve 11 are operated. It is necessary to manually calculate the operation timing of each part, in particular, the time from opening and closing of the valve 5 to driving of the pump 9 based on this.

By the way, the center nozzle 8 sends the resist 2
Since the spread of the resist 2 on the wafer 14 after the discharge of the resist 2 depends on the viscosity of the resist 2 and the surface condition of the wafer 14 at that time, the resist is always transmitted from the side nozzle 13 at an optimal timing. From the viewpoint of ejecting No. 2, it is more preferable to adopt the apparatus configuration shown in FIGS.

[0036]

As described above, according to the resist coating apparatus of the present invention, the first method for discharging the resist to the wafer center position on the wafer held by the wafer holding mechanism.
In addition to the application nozzle, a second application nozzle that discharges the resist at a position shifted by a predetermined distance from the center position of the wafer in the radial direction of the wafer is provided. This can prevent the occurrence of coating unevenness in the peripheral portion of the wafer due to the above. As a result, it is possible to form a resist film having a uniform thickness on a wafer while minimizing the consumption of the resist to a necessary minimum, so that it is possible to simultaneously reduce the resist and make the film thickness uniform. Further, since the resist can be directly discharged from the second application nozzle to the peripheral portion of the wafer, it is possible to suitably cope with a future increase in the diameter of the wafer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a resist coating apparatus according to the present invention.

FIG. 2 is a functional block diagram illustrating an internal configuration of a main control unit according to the embodiment.

FIG. 3 is a diagram showing a relationship between a nozzle position and a resist application range.

FIG. 4 is a diagram illustrating a state of application of a resist according to the embodiment.

FIG. 5 is a schematic configuration diagram of a conventional resist coating apparatus.

FIG. 6 is a diagram showing a state of application of a conventional resist.

[Explanation of symbols]

1 ... resist bottle, 2 ... resist, 3, 9 ... pump,
5, 11 ... valve, 8 ... center nozzle (coating nozzle),
13 ... side nozzle (coating nozzle), 14 ... wafer, 1
5: Spin chuck, 16: Spin motor, 17: Imaging camera, 18: Main control unit

Claims (2)

[Claims] A resist coating apparatus for forming a resist film on a wafer by dropping a resist on the wafer and rotating the wafer, wherein the wafer is held substantially horizontally, and the held wafer is A wafer holding mechanism for rotating, a first coating nozzle for discharging a resist at a center position of the wafer held by the wafer holding mechanism, and a center of the wafer holding the wafer held by the wafer holding mechanism. A second coating nozzle for discharging the resist at a position shifted from the position by a predetermined distance in the radial direction of the wafer. 2. A detecting means for detecting a spread state of a resist discharged on the wafer by the first coating nozzle, and a discharge of the resist by the second coating nozzle based on a detection result of the detecting means. 2. The resist coating apparatus according to claim 1, further comprising control means for controlling timing.