JP3559144B2 - Substrate processing equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention applies a film-forming chemical such as a photoresist to a thin plate-like substrate (hereinafter, referred to as a “substrate”) such as a semiconductor substrate or a liquid crystal glass substrate, and forms a film on a main surface of the substrate. The present invention relates to a substrate processing apparatus for performing
[0002]
[Prior art]
A photoresist (hereinafter, simply referred to as “resist”) having photosensitivity to light for forming a pattern or the like is applied to the substrate as described above. In this case, the substrate is rotated. In general, a method of discharging a resist solution from a nozzle and uniformly applying a resist film on a substrate surface is used. At this time, it is necessary to change the thickness of the resist applied according to the characteristics required for the substrate.
[0003]
Conventionally, a plurality of nozzles capable of discharging resist solutions having different viscosities are provided, and the thickness of the resist is changed by switching the plurality of nozzles. That is, use a low-viscosity resist nozzle when you want to form a thin resist film, use a high-viscosity resist nozzle when you want to form a thick resist film, and use it when you want to form a medium-thick resist film. A medium viscosity resist nozzle was used.
[0004]
However, in the case described above, a nozzle must be provided for each required film thickness, and the number of nozzles in the entire apparatus increases, the piping system becomes complicated, and cost increases and maintenance efficiency decreases. Had a problem.
[0005]
[Problems to be solved by the invention]
Therefore, the inventors have devised a technique of mixing a resist stock solution and a solvent with a single nozzle and variably adjusting the viscosity of the resist solution discharged onto the substrate. In this technique, the resist viscosity after mixing is measured, and the mixing ratio between the resist stock solution and the solvent is controlled so as to obtain the optimum viscosity. Therefore, an arbitrary resist film thickness can be obtained with a single nozzle. The system can also be simplified.
[0006]
However, it takes a certain amount of time to obtain a resist solution having an optimum viscosity by controlling the mixing ratio between the resist stock solution and the solvent based on the viscosity information of the resist solution after mixing. That is, when changing the resist film thickness to be applied, immediately after changing the setting of the resist solution viscosity necessary for obtaining the film thickness, the resist viscosity is not an appropriate value, and the resist solution is used. Cannot be applied. Therefore, the resist solution is unnecessarily discharged until the resist viscosity is adjusted to an appropriate value, which is not preferable. In particular, since the chemically amplified resist that has been used in recent years is very expensive, the amount of wasted resist solution must be reduced as much as possible.
[0007]
The present invention has been made in view of the above problem, and has as its object to provide a substrate processing apparatus capable of suppressing wasteful consumption of a chemical solution and effectively using the chemical solution.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a substrate processing apparatus that performs a film forming process on a main surface of a substrate by applying a film forming chemical to a rotating substrate, and (a) (B) a nozzle for discharging the supplied chemical liquid onto the main surface of the substrate, and (c) a chemical liquid supply means provided in a supply path from the chemical liquid supply means to the nozzle and supplied. Chemical liquid viscosity detecting means for detecting the viscosity of the chemical liquid, (d) substrate rotating means for rotating the substrate, and (e) changing the rotation speed of the substrate according to the chemical liquid viscosity detected by the chemical liquid viscosity detecting means. Rotation control means for controlling the substrate rotation means, and (f) viscosity control for controlling the chemical liquid supply means to change the viscosity of the supplied chemical liquid according to the chemical liquid viscosity detected by the chemical liquid viscosity detection means. Means .
[0009]
The invention of claim 2 is the substrate processing apparatus according to the invention of claim 1, the chemical solution supply unit, (a-1) and the solution feed means for feeding a stock solution of the drug solution, (a-2) wherein A solvent supply means for supplying a solvent for diluting the undiluted solution, and (a-3) a mixing means for mixing the undiluted solution and the solvent, wherein the viscosity control means is detected by the chemical viscosity detection means. The solvent supply means is controlled so that the supply amount of the solvent is changed according to the viscosity of the chemical solution.
[0010]
According to a third aspect of the present invention, in the substrate processing apparatus according to the first or second aspect of the present invention, when a chemical having a chemical viscosity detected by the chemical viscosity detecting means is applied to the rotation control means. The substrate rotating means is controlled so as to change the rotational speed of the substrate to a rotational speed capable of forming a predetermined film thickness.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, terms used in the present specification will be described. In the present specification, the “resist stock solution (stock solution of chemical solution)” refers to a solution containing a resin component and a photosensitive agent or a solution obtained by adding a predetermined solvent to a solution containing a resin component and a photosensitive agent in advance, The “resist solution (chemical solution)” refers to a solution obtained by further diluting a solvent by adding a solvent to a resist stock solution. Further, the viscosity of the resist solution is simply referred to as “resist viscosity”.
[0013]
A. Configuration of substrate processing equipment:
FIG. 1 is a perspective view of a main part of a substrate processing apparatus according to the present invention. This substrate processing apparatus is a rotary resist coating apparatus (spin coater) that sprays a resist solution onto the substrate W while rotating the substrate W by a spin motor 60 to form a resist film having a uniform and predetermined thickness. The substrate processing apparatus includes a nozzle 10 for ejecting a resist solution, a nozzle arm 15 for holding the nozzle 10 and guiding the resist solution to the nozzle 10, a motor 20 for rotating the nozzle 10 and the nozzle arm 15, A spin motor 60 for rotating W.
[0014]
The substrate W is suction-held by the turntable 65 in a horizontal posture. The rotating table 65 has a rotating shaft 66 suspended from the center of the lower surface, and the rotating shaft 66 is connected to the spin motor 60. Then, the rotation of the spin motor 60 is transmitted to the turntable 65 via the rotation shaft 66, and the substrate W held on the turntable 65 rotates about the vertical direction as an axis.
[0015]
An encoder 70 is provided below the spin motor 60. The encoder 70 has a function of detecting the rotation speed of the spin motor 60, that is, the rotation speed of the substrate W.
[0016]
The motor 20 is fixed to a housing of the substrate processing apparatus main body, and a pulley 22 is directly connected to a motor shaft 21 of the motor 20. The lower end of the arm lower portion 15a of the nozzle arm 15 is inserted into the outer cylinder 32, and a pulley 31 is provided on the outer periphery of the outer cylinder 32. The rotational motion of the motor 20 is transmitted to the outer cylinder 32 via the motor shaft 21, the pulley 22, the belt 25, and the pulley 31. Since the outer cylinder 32 is rotatably provided on the support base 33 fixed to the housing of the substrate processing apparatus main body, the nozzle arm 15 rotates with the rotation of the motor 20. By the rotation operation of the nozzle arm 15, the nozzle 10 can move between a retracted position when transferring the substrate W and a processing position when performing resist coating on the substrate W.
[0017]
The nozzle arm 15 is a hollow tube, and the nozzle 10 is provided at one end of an upper portion 15b of the arm. On the other hand, the lower end of the arm lower portion 15a is connected to a resist stock solution supply line (not shown) via a support 33, and the resist stock solution supply line is connected to the resist stock solution supply means 1 (see FIG. 3 described later). Further, in the nozzle arm 15, a mixing section 50 for mixing a resist stock solution and a solvent is provided between the arm lower portion 15a and the arm upper portion 15b.
[0018]
FIG. 2 is a cross-sectional view of the mixing section 50. In this figure, solid arrows indicate the flow of the fluid. As shown, a pipe 45 for guiding a solvent from a solvent supply means 2 (not shown) (see FIG. 3 described later) is connected to the mixing section 50. In the mixing section 50, right elements 51 and left elements 52 are alternately arranged along the traveling direction of a fluid such as a resist stock solution or a solvent. The rotation direction of the fluid is opposite between the right element 51 and the left element 52, and the liquid passing through both elements is sufficiently stirred and mixed by reversing the rotation direction. Therefore, the undiluted resist solution and the solvent that have flowed into the mixing section 50 are sufficiently mixed by the mixing section 50, flow through the upper arm 15b of the nozzle arm 15 as a resist solution, and are discharged from the nozzle 10 to the substrate W. .
[0019]
Returning to FIG. 1, a viscometer 41 is installed on the upper arm portion 15 b of the nozzle arm 15. The viscometer 41 detects the viscosity of a resist solution obtained by mixing a resist stock solution and a solvent. The viscosity of the resist solution is a value that changes depending on the mixing ratio of the resist stock solution and the solvent, and the thickness of the resist applied to the substrate W is determined by the viscosity of the resist solution and the rotation speed of the substrate W.
[0020]
In the substrate processing apparatus according to the present invention, the viscosity of the resist solution (mixing ratio of the undiluted resist and the solvent) and the number of rotations of the substrate W (number of rotations of the spin motor 60) are determined based on the result measured by the viscometer 41. Controlled. FIG. 3 is a functional block diagram showing a control mechanism in the substrate processing apparatus according to the present invention. In this figure, solid arrows indicate flows of fluids such as resist stock solutions and solvents, and dotted arrows indicate transmission of electric signals.
[0021]
In the substrate processing apparatus, a constant amount of the resist stock solution is always supplied from the resist stock solution supply unit 1. Then, the resist stock solution is mixed with the solvent supplied from the solvent supply means 2 in the mixing section 50, and is guided to the nozzle 10. Here, the viscosity of the mixed resist solution is measured by the viscometer 41, and the measurement result is transmitted to the control unit 5 provided in the substrate processing apparatus.
[0022]
The control unit 5 includes a rotation control unit 6 and a viscosity control unit 7. The rotation control means 6 and the viscosity control means 7 represent processing contents executed according to processing software stored in a storage means (not shown) attached to the control unit 5. The rotation control means 6 is electrically connected to the encoder 70 and the spin motor 60, sends a command to the spin motor 60 while referring to the information transmitted from the encoder 70, and controls the rotation speed of the substrate W. The viscosity control means 7 is electrically connected to the solvent supply means 2, and adjusts the amount of solvent supply in the solvent supply means 2 based on the set value of the resist viscosity input to the apparatus. Control the viscosity of the solution. The processing contents of the rotation control means 6 and the viscosity control means 7 will be further described later.
[0023]
B. Substrate processing procedure:
Next, a substrate processing procedure in the substrate processing apparatus according to the present invention will be described. FIG. 4 is a flowchart showing a substrate processing procedure in the substrate processing apparatus.
[0024]
First, in step S1, the viscosity of the mixed resist is detected by the viscometer 41, and then in step S2, the control unit 5 determines whether or not the resist viscosity has changed. When a normal resist coating process is performed, the resist viscosity does not change. When the resist viscosity changes, the set value of the supplied resist viscosity is changed, and the viscosity control unit 7 changes the resist viscosity. It is conceivable that the solvent supply means 2 is controlled so as to perform the control. Then, at this time, in order to bring the resist viscosity closer to the target value (here, the above-mentioned set value), the viscosity control means 7 controls the solvent supply amount of the solvent supply means 2 to adjust the resist viscosity (step S3).
[0025]
When adjusting the resist viscosity, the viscosity controller 7 performs feedback control based on the viscosity of the resist solution detected by the viscometer 41. Specifically, the viscosity control means 7 has a look-up table (hereinafter, simply referred to as “table”) as shown in FIG. In the figure, the horizontal axis represents the input value obtained by subtracting the target resist solution viscosity (the above target value) from the viscosity of the resist solution detected by the viscometer 41, and the vertical axis represents the viscosity control means 7 The amount of increase in the solvent supply amount to be commanded is shown. Then, as shown in the figure, when the detected viscosity of the resist solution is higher than the target resist solution viscosity, the supply amount of the solvent is increased, and when it is low, the supply amount of the solvent is decreased. The adjustment of the resist viscosity is not limited to such a form, and any known form in which feedback control is performed based on the viscosity of the resist solution detected by the viscometer 41 can be applied.
[0026]
It takes a certain amount of time to adjust the resist viscosity by controlling the solvent supply amount as described above. When the resist coating process is performed on the substrate W using the resist solution while the resist viscosity is being adjusted, the resist film after the coating process becomes uneven because the viscosity of the resist solution is not constant. Therefore, in the substrate processing apparatus according to the present invention, the rotation speed of the substrate W is adjusted according to the viscosity of the resist solution detected by the viscometer 41 (Step S4).
[0027]
The rotation speed of the substrate W is adjusted by the rotation control means 6 controlling the spin motor 60 based on the viscosity of the resist solution detected by the viscometer 41. The rotation control means 6 also has a table as shown in FIG. 5, and instructs the spin motor 60 on the number of rotations of the substrate W based on the table. The rotation speed of the substrate W is detected by the encoder 70, and the rotation control means 6 controls the spin motor 60 while referring to the detection result.
[0028]
5, the horizontal axis indicates the viscosity of the resist solution detected by the viscometer 41, and the vertical axis indicates the number of rotations of the substrate W output by the rotation control means 6. Then, as shown in FIG. 5, different output values are obtained for each required resist film thickness (film thickness t _{1 to} t _{3 in} this example). That is, for example, when the viscosity of the resist solution detected by the viscometer 41 is v ₁ and the required resist film thickness is t ₁ , the spin motor 60 is rotated so that the number of rotations of the substrate W becomes r _1. controls, resist thickness required by the case of the film thickness t ₂ controls the spin motor 60 so that the rotational speed of the substrate W is r _2. Likewise, the resist film thickness required by the rotational speed of the substrate W in the case of the film thickness t ₃ is the rotation control means 6 so that the r ₃ controls the spin motor 60.
[0029]
In addition, as shown in FIG. 5, when the detected viscosity of the resist solution is low, the rotational speed of the substrate W is reduced along a line having a constant thickness on the table, and conversely, the detected viscosity of the resist solution is reduced. Is high, the rotation speed of the substrate W is increased along the line having the constant film thickness, and the spin motor 60 is controlled so as to always obtain a substantially constant resist film thickness.
[0030]
Returning to FIG. 4, in step S5, the control unit 5 determines whether the viscosity of the resist solution has reached an appropriate value. That is, it is determined whether or not the viscosity of the resist solution detected by the viscometer 41 matches the target value, and if so, a series of processing ends. On the other hand, if the viscosity of the resist solution detected by the viscometer 41 is different from the target value, the process returns to step S3, and the above processing is repeated until the viscosity of the resist solution becomes an appropriate value.
[0031]
To summarize the above contents, when changing the resist viscosity, the viscosity control means 7 controls the solvent supply amount of the solvent supply means 2 to adjust the resist viscosity so that the resist viscosity becomes a target value. This adjustment requires a certain amount of time. On the other hand, when the rotation control means 6 controls the spin motor 60 to adjust the rotation speed of the substrate W according to the resist viscosity, the spin motor 60 reacts immediately, so that the rotation speed adjustment of the substrate W is not performed. It takes place in a relatively short time. Therefore, the substrate processing apparatus according to the present invention pays attention to this point, adjusts the number of rotations of the substrate W during the time required for adjusting the resist viscosity, and maintains a substantially constant resist even during the adjustment of the resist viscosity. The film thickness is obtained.
[0032]
In this way, since the coating process is performed using the resist solution until the resist viscosity is adjusted to the target value, the resist is prevented from being wasted and the resist is effectively used. It can be carried out.
[0033]
Further, in the above embodiment, the case where the viscosity of the resist solution is intentionally changed has been described. However, the case where the viscosity of the resist solution inevitably changes due to the change in the concentration of the resist stock solution may be considered. Can be In such a case, the original value of the resist viscosity is set as the target value, and if the same processing procedure is performed as described above, the resist solution is applied using the resist solution until the resist viscosity is adjusted to the target value. Since the processing is performed, it is possible to prevent the resist from being wasted.
[0034]
However, as a cause of the change in the concentration of the resist stock solution, the concentration of the resist stock solution often changes minutely due to a change in the lot of the resist stock solution. Therefore, in this case, since the change in the resist viscosity is very small, it is not always necessary to adjust the resist viscosity to the original one, and only the rotation speed of the substrate W may be adjusted according to the resist viscosity after the change. Even in this case, the thickness of the resist film applied to the substrate W is maintained at a substantially constant value.
[0035]
As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above example. For example, in the above, a resist is used as a chemical for film formation, but a predetermined film thickness is obtained. For example, other chemicals may be used as long as the chemicals are used, for example, a chemical for ARC (anti-reflective coating).
[0036]
In the above embodiment, the spin motor 60 is controlled (so-called feedback control) while detecting the rotation speed of the substrate W by the encoder 70. However, the encoder 70 is not necessarily essential, and the viscometer 41 detects the rotation. Open loop control in which the rotation control means 6 sends only the command value to the spin motor 60 based on the viscosity of the resist solution may be employed.
[0037]
【The invention's effect】
As described above, according to the first to third aspects of the present invention, the rotation control for controlling the substrate rotating means so as to change the rotation speed of the substrate in accordance with the chemical viscosity detected by the chemical viscosity detecting means. Since the means is provided, even when the viscosity of the supplied chemical solution changes, it is possible to change the rotation speed of the substrate according to the viscosity and maintain the film thickness on the substrate substantially constant. It is possible to effectively use the chemical solution without wasting the chemical solution after the viscosity change.
[0038]
Moreover, since further comprises a viscosity control means for controlling the chemical liquid supply means to change the viscosity of the chemical solution is supplied in accordance with the chemical solution viscosity detected by chemical liquid viscosity detecting means, for supplying a chemical solution of a desired viscosity And the thickness of the film formed on the substrate can be kept substantially constant by changing the rotation speed of the substrate in accordance with the changing viscosity until the viscosity is adjusted. It is possible to suppress unnecessary consumption of the liquid medicine being adjusted, and to effectively use the liquid medicine.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a substrate processing apparatus according to the present invention.
FIG. 2 is a sectional view of a mixing unit in the substrate processing apparatus of FIG.
FIG. 3 is a functional block diagram showing a control mechanism in the substrate processing apparatus of FIG.
FIG. 4 is a flowchart showing a substrate processing procedure in the substrate processing apparatus of FIG. 1;
FIG. 5 is a view showing a look-up table for adjusting the number of rotations of a substrate;
FIG. 6 is a view showing a lookup table for adjusting a solvent supply amount.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 resist stock solution supply means 2 solvent supply means 6 rotation control means 7 viscosity control means 10 nozzle 41 viscometer 50 mixing section 60 spin motor 70 encoder

Claims (3)

In a substrate processing apparatus that performs a film forming process on a main surface of a substrate by applying a liquid chemical for film formation to a rotating substrate,
(a) a chemical supply means for supplying the chemical,
(b) a nozzle for discharging the supplied chemical liquid to the main surface of the substrate,
(c) provided in a supply path from the chemical liquid supply means to the nozzle, and a chemical liquid viscosity detection means for detecting the viscosity of the supplied chemical liquid,
(d) substrate rotating means for rotating the substrate,
(e) rotation control means for controlling the substrate rotation means so as to change the rotation speed of the substrate according to the chemical viscosity detected by the chemical viscosity detection means,
(f) viscosity control means for controlling the chemical supply means so as to change the viscosity of the chemical supplied in accordance with the chemical viscosity detected by the chemical viscosity detection means,
A substrate processing apparatus comprising: The substrate processing apparatus according to claim 1,
The chemical solution supply means,
(a-1) a stock solution supply means for supplying a stock solution of the chemical solution,
(a-2) a solvent supply means for supplying a solvent for diluting the stock solution,
(a-3) mixing means for mixing the stock solution and the solvent,
With
The substrate processing apparatus, wherein the viscosity control unit controls the solvent supply unit so as to change a supply amount of the solvent in accordance with the chemical viscosity detected by the chemical viscosity detection unit. The substrate processing apparatus according to claim 1 or 2,
The rotation control means,
Controlling the substrate rotating means so as to change the rotation number of the substrate to a rotation number capable of forming a predetermined film thickness when a chemical having the chemical viscosity detected by the chemical viscosity detection means is applied. Substrate processing apparatus.

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