JPH10335201A - Substrate treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate-treating apparatus capable of fully ensuring film thickness uniformity of chemical coating against atmospheric pressure variation. SOLUTION: A table TB is provided, showing the relation of the viscosity of a resist liq. for obtd. a resist film of specified thickness to the ambient pressure around a substrate, and stored in a memory 46. A static pressure sensor 42 detects the ambient pressure around the substrate for specifying the solvent feed rate corresponding to the ambient pressure in the table TB and an instruction signal, for designating this solvent feed rate is given to a pump 26 to feed a solvent according to a designated feed. At a mixer 50, the solvent is mixed with a soln. and fed to a nozzle 52. If the atmospheric pressure changes, it is measured as the ambient pressure according to which the viscosity is adjusted to keep the required film thickness against atmospheric pressure variation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing apparatus for applying a chemical such as a resist to a substrate for a precision electronic device such as a semiconductor substrate or a liquid crystal substrate (hereinafter referred to as "substrate").

[0002]

2. Description of the Related Art In a photolithography process for a semiconductor substrate, it is necessary to apply a resist solution on the substrate to form a resist film. Here, the size (diameter) of the semiconductor substrate is increasing with the times, and the demand for the degree of integration of the pattern on the substrate is also increasing. Therefore, it is necessary to reduce the resist film thickness on the substrate.
For example, a film thickness of about 1-2 μm or less is required.

In order to form a thin resist film on such a large-diameter substrate with a uniform film thickness, it is necessary to lower the viscosity of the resist solution to increase the fluidity. This is because, when a resist liquid having a high viscosity is used, the resist liquid rises on the substrate due to the viscosity and does not spread thinly over the entire substrate.

[0004]

However, it has been observed that when the viscosity of the resist solution is reduced as described above, the state of the applied resist film thickness varies from day to day. Therefore, as a result of studying and investigating this phenomenon, it was found that the cause was the fluctuation of the atmospheric pressure.

That is, although the resist liquid is a liquid, it is an incompressible fluid when viewed macroscopically. However, when it is applied on a substrate, it is an extremely thin layer, so that a microvolume change occurs. It is affected by the surrounding air pressure.

Specifically, when the atmospheric pressure is high, the resist solution on the substrate is in a state of being crushed, and the film thickness of the resist becomes thinner than necessary. In this case, the film formability is deteriorated, and a small hole (pinhole) is formed.

On the other hand, when the atmospheric pressure is low, the resist solution tends to swell and the resist film becomes thick. As a result, it is difficult to accurately form a fine pattern in the subsequent exposure step and etching step.

It has been confirmed that such a change in the film thickness due to a change in the atmospheric pressure reaches about 50 angstroms. This problem is not limited to an application apparatus for applying a resist solution to a semiconductor substrate, but also to a general apparatus for applying a chemical solution onto a substrate to form a required film.

The present invention intends to overcome the above-mentioned problems in the prior art, and provides a substrate processing apparatus capable of forming a film having a uniform and uniform thickness while preventing the influence of atmospheric pressure fluctuation. The purpose is to provide.

[0010]

According to a first aspect of the present invention, there is provided a substrate processing apparatus for forming a predetermined film on a substrate by applying a predetermined chemical solution to the substrate.
(A) chemical solution supply means for supplying the chemical solution on the substrate,
(b) Atmospheric pressure measuring means for measuring an atmospheric pressure near the substrate; and (c) a chemical viscosity adjusting means for adjusting the viscosity of the chemical according to the atmospheric pressure.

According to a second aspect of the present invention, in the substrate processing apparatus according to the first aspect, the chemical solution viscosity adjusting means comprises:
1) storage means for storing in advance the correspondence between the value of the atmospheric pressure and the viscosity adjustment value of the chemical solution, and (c-2) for the atmospheric pressure measured by the atmospheric pressure measuring means, A specifying means for specifying a corresponding viscosity adjustment value from the correspondence, and (c-3) the viscosity of the chemical supplied to the substrate from the chemical supply means according to the viscosity adjustment value specified by the specifying means. And a viscosity changing means for changing the viscosity.

According to a third aspect of the present invention, in the substrate processing apparatus according to the second aspect, the chemical liquid supply means comprises: (a-1) a raw liquid supply means for supplying a raw liquid of the chemical liquid; And (a-3) mixing means for mixing the stock solution and the chemical solution.

[0013] The viscosity adjustment value is an amount of the solvent supplied to the mixing means, and the viscosity changing means determines the viscosity in accordance with the viscosity adjustment value specified by the specifying means.
The amount of the solvent supplied from the solvent supply means to the mixing means is changed.

According to a fourth aspect of the present invention, there is provided the substrate processing apparatus according to any one of the first to third aspects, wherein (d) a chemical solution viscosity measuring means for measuring the viscosity of the chemical solution; Viscosity feedback control means for feeding back the viscosity value measured by the measurement means to the chemical liquid viscosity adjustment means is further provided.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<A. Schematic Configuration of Substrate Processing Apparatus> First, a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention will be described with reference to FIG. The substrate processing apparatus 1 in this embodiment is configured as a semiconductor substrate spin coating apparatus (spin coater). At the center of the apparatus, a spin chuck 10 for holding the substrate W by vacuum suction in a substantially horizontal state is arranged, and the rotation shaft 11 of the spin chuck 10 is driven to rotate by a substrate rotation driving motor M. The substrate W together with the spin chuck 10 rotates in a horizontal plane around this axis.

On the other hand, a coating liquid collecting cup 12 made of resin is provided to prevent the excess coating liquid from scattering around and to collect the excess coating liquid and guide it to a predetermined coating liquid collecting path. The spin chuck 10 and the substrate W are accommodated in the coating liquid recovery cup 12. At the bottom of the coating liquid recovery cup 12, a drain hole 14 for waste liquid and exhaust is provided.

A chamber 16 that completely surrounds the entire coating solution recovery cup 12 is provided. In the chamber 16, an air supply port 30 is formed above the substrate W held in vacuum by the spin chuck 10, and an air supply device 32 is connected to the air supply port 30 via an air supply line 40. . The air supply device 32 includes an air supply fan 34, an air supply amount adjustment damper 36, and a filter 38 disposed for the purpose of removing particles and the like, thereby providing an air flow path into the chamber 16. Has formed. Then, clean air adjusted to the same constant temperature and humidity as the clean room is supplied from the air supply device 32 through the air supply line 40 and the air supply port 30 into the chamber 16.

On the other hand, an exhaust port 18 is formed near the bottom of the chamber 16, and an exhaust pipe 20 is connected to the exhaust port 18. Then, the chamber 16 is supplied through the air supply port 30.
The clean air supplied to the inside flows from the upper part to the lower part in the chamber 16, and is discharged to the exhaust pipe 20 through the exhaust port 18. This displacement can be adjusted by the damper 22.

A window 24 for carrying in / out the substrate W is formed in the chamber 16, and the window 24 is closed with a lid 26 except for the carrying in / out of the substrate W. The transfer of the substrate W into and out of the chamber 16 is performed by a transfer robot (not shown).
Done by In the chamber 16, the atmospheric pressure around the substrate W (specifically, the atmospheric pressure inside the chamber 16)
Is disposed. And
The static pressure sensor 42 is configured to detect the atmospheric pressure in the chamber. A nozzle 52 is provided above the substrate W to supply a resist solution to the upper surface of the substrate W.

<B. Structure near Nozzle> FIG. 2 is an enlarged perspective view around the nozzle 52 in the substrate processing apparatus 1. In FIG. 2, the nozzle arm 54 is a hollow tube, and the nozzle 52 is provided at one end of the upper part thereof. On the other hand, an arm lower portion 55 of the nozzle arm 54 is supported by a support base (not shown).

The undiluted resist solution supplied from the nozzle lower portion 55 by means described later enters the mixing section 50. Mixing unit 5
Further, a solvent for diluting the undiluted resist solution is supplied to the tube 0 through a pipe 51.

In FIG. 2, solid arrows in the mixing section 50 indicate fluids. The mixing unit 50 includes a right element 56 along the traveling direction of a fluid such as a resist solution or a solvent.
And the left element 58 are alternately arranged. The rotation direction of the fluid is opposite between the right element 56 and the left element 58, and the liquid passing through both elements is sufficiently stirred and mixed by reversing the rotation direction. Therefore, the resist stock solution and the solvent that have flowed into the mixing section 50 are sufficiently mixed by the mixing section 50 and flow through the nozzle arm 54 as a resist solution (solution).
2 is discharged onto the substrate W.

The mixing section 50 of the nozzle arm 54
A viscometer 90 is installed on the side part. The viscometer 90 detects the viscosity of a resist solution obtained by mixing a resist stock solution and a solvent. The viscosity of this resist solution is
It is output as a signal value indicating the mixing ratio of a certain amount of the resist stock solution and the variable supply amount solvent.

<C. Control System> FIG. 3 is a main functional block diagram showing a control system of the substrate processing apparatus 1. First, in the resist stock solution supply means 70, the resist stock solution in the resist bottle 71 is pumped up by the pump 72, and
Pump to zero. In the solvent supply means 60,
The solvent in the solvent bottle 61 is pumped up by the pump 62 and sent to the mixing section 50 under pressure. The undiluted resist solution and the solvent are mixed by the mixing unit 50 described with reference to FIG. 2, and are discharged from the nozzle 52 onto the substrate W as a resist solution.

On the other hand, a detection signal value of the atmospheric pressure around the substrate (the atmospheric pressure in the chamber 16) detected by the static pressure sensor 42 is input to the control unit 44. In order to give the resist solution an appropriate viscosity corresponding to the atmospheric pressure, the control unit 44
Controls the operation speed of the pump 62 in the solvent supply unit 60 by an operation described later, and adjusts the amount of the solvent supplied from the pump 62 to the mixing unit 50.

The control unit 44 is constituted by a microcomputer or the like, and includes a CPU 45 and a memory 46. In this memory 46, in addition to a control program and the like, a table TB as shown in FIG. This table TB shows the correspondence between various values of the atmospheric pressure assumed in advance and the supply amount of the solvent necessary to obtain a predetermined film thickness at those atmospheric pressures.
It is in the form of a numerical table. This solvent supply amount has a meaning as a viscosity adjustment amount for adjusting the viscosity of the resist solution. Such a table TB can be prepared by actually measuring and obtaining in advance a solvent supply amount that can obtain a required film thickness under various atmospheric pressures.

Here, the relationship between the atmospheric pressure and the supply amount of the solvent in the table TB will be described. Figure (b)
As shown in (2), the required film thickness can be obtained by increasing the viscosity of the resist solution generally as the atmospheric pressure increases. Therefore, when the supply amount of the resist stock solution per unit time is fixed, as shown in FIG. 4C, the solvent supply amount per unit time asymptotically decreases as the atmospheric pressure increases. It becomes a relationship that makes you. Such a relationship is determined as a specific numerical value, is set as a table TB, and is stored in the memory 46.

On the other hand, as shown in FIG. 3, a detection signal of the viscometer 90 is also input to the controller 44. This is because when an appropriate solvent supply amount is determined from the table TB in FIG. 4 according to the atmospheric pressure measured at that time, it is monitored whether or not the viscosity corresponding to the solvent supply amount is actually realized. This is for performing feedback control according to the result.

<D. Control Operation> Next, a substrate processing procedure in the substrate processing apparatus 1 will be described with reference to a flowchart of FIG.

First, the viscosity of a resist solution required to form a required film thickness for various values of the atmospheric pressure is actually measured as a value of a solvent supply amount (step S1). Then, the correspondence obtained in this manner is stored in the memory 46 of the control unit 44 in the form of the table TB in FIG. 4A (step S2). The procedure up to this point may be performed by the device manufacturer, or may be performed by the user of the device 1.

When the input of all data is completed, the actual resist coating process is started using the substrate processing apparatus (step S3).

Before the substrate is loaded into the apparatus 1, the air supply device 32 is operated. Thereafter, the air supply device 32 keeps the environmental temperature and humidity in the chamber 16 constant.

After the supply of air to the chamber 16 and the exhaust from the chamber 16 are stabilized, the static pressure sensor 42
The atmospheric pressure in the inside is read (step S4). The CPU 45 of the control unit 44 transmits the read data of the measured atmospheric pressure value.
Is retrieved from the table TB on the memory 46 for an atmospheric pressure value that matches the value (step S5).
Then, the CPU 45 specifies the solvent supply amount corresponding to the measured atmospheric pressure value on the table TB when the measured atmospheric pressure value is present on the table TB. , The value of the solvent supply amount is specified by interpolation (interpolation) or extrapolation of the numerical value sequence of the solvent supply amount on the table TB.

Next, after the substrate W is carried into the chamber 16 and held by the chuck 10, a specific solvent supply amount value determined as described above (hereinafter, referred to as a "solvent supply amount command value") is shown. The signal is transmitted to the solvent supply means 60. In the solvent supply means 60, a drive signal corresponding to the solvent supply amount command value is given to the pump 62 (Step S).
6) The amount of the solvent per unit time according to the command value is sent from the pump 62 to the mixing unit 50. The solvent whose supply amount has been automatically adjusted in this way is mixed with the resist stock solution in the mixing section 50 and is supplied from the nozzle 52 onto the rotating substrate W. A constant amount of the resist stock solution is always supplied from the resist stock solution supply unit 70 after the start of the coating on the substrate W until the coating of the required number of substrates is completed. Therefore, a resist liquid having a viscosity corresponding to the atmospheric pressure is discharged onto the substrate W by such a solvent supply amount control.

On the other hand, the viscosity of the resist solution mixed in the mixing section 50 is measured by the viscometer 90 (step S7). The measured value of the viscometer 90 is given to the control unit 44, and the control unit 44 determines whether or not the viscosity of the resist solution has reached an appropriate value. Here, first,
The CPU 45 converts the generated solvent supply amount command value into a value of a stock solution / solvent mixture ratio. That is, when the supply amount of the stock solution per unit time is V0 and the solvent supply amount per unit time is VS, the R of the stock solution / solvent mixture ratio corresponding to this is given by R = V0 / VS. However, since the supply amount V0 of the stock solution is constant, an appropriate value of the stock solution / solvent mixture ratio R can be obtained by substituting the solvent supply amount command value as the solvent supply amount VS. Then, the CPU 45 compares the measured value of the mixing ratio from the viscometer 90 with the appropriate value (step S8). Note that such an appropriate value of the stock solution / solvent mixture ratio may be calculated in advance for each value of the atmospheric pressure and registered in accordance with the table TB in FIG.

In the comparison in step S8, the viscometer 9
The CPU 45 determines whether or not the measured value of the mixing ratio from 0 and its proper value match within a predetermined allowable range.

If there is a discrepancy outside the allowable range,
The solvent supply command value from the solvent supply means 60 is set in step S1.
The value is changed by a predetermined minute amount at 0, and the process returns to step S6.
By adding such a feedback control system for viscosity, it is possible to compensate for an error caused by a difference between the command value and the actual amount of solvent supplied, and to perform stable viscosity adjustment.

On the other hand, if it is determined in step S9 that the values match within the predetermined allowable range, the process returns to the atmospheric pressure reading step (step S4), and the atmospheric pressure is monitored again. Therefore, if the atmospheric pressure fluctuates, the viscosity of the resist solution can be changed accordingly.

Then, when an interrupt signal instructing the completion of the application of the resist liquid onto the substrate W is received, the process exits from such an atmospheric pressure monitoring routine, stops the discharge of the resist liquid, and moves the substrate W to the next step. (Not shown).

By automatically adjusting the viscosity as described above, even if the atmospheric pressure changes due to a weather change, such a change in the atmospheric pressure is monitored around the substrate, and the viscosity of the resist solution is compensated for. Automatically changes, so that the resist film thickness becomes constant. As a result, appropriate film formation can be performed even on a large-diameter substrate having a high degree of element integration.

<E. Modification> In the above embodiment, the solvent supply amount is adopted as the “viscosity adjustment value”, and the viscosity is adjusted by increasing or decreasing the supply amount of the solvent. The adjustment may be made according to the supply amount, or both may be changed.

However, since the components finally remaining on the substrate after the evaporation of the solvent are mainly the components on the stock solution side, it is preferable to change only the amount of the solvent as in the above embodiment for the purpose of only adjusting the viscosity.

For the viscosity adjustment based on the measurement of the atmospheric pressure, for example, the atmospheric pressure may be measured for each substrate or for each lot and a viscosity adjustment routine based on the measurement may be executed. Also,
Most of the change in the atmospheric pressure near the substrate is caused by the change in the atmospheric pressure, and the change in the atmospheric pressure is usually not so sharp, so that the adjustment may be performed several times a day, for example.

It is not essential to make the relationship between the atmospheric pressure and the viscosity (adjustment amount) into a numerical table, but it may be made into a function using, for example, an approximate function.

The present invention is applicable not only to the application of a resist solution to a semiconductor substrate, but also to a general apparatus for forming a film by applying a chemical solution onto a substrate.

[0047]

As described above, in the substrate processing apparatus according to the first to fourth aspects of the present invention, the viscosity of the chemical solution is adjusted according to the atmospheric pressure in the vicinity of the substrate. Therefore, even when the atmospheric pressure fluctuates, uniformity of the film thickness in the application of the chemical solution can be sufficiently ensured.

In particular, according to the second aspect of the present invention, the correspondence of which viscosity adjustment value is appropriate for a specific value of the atmospheric pressure is stored in the storage means in advance, so that the change in the atmospheric pressure can be changed. , The corresponding viscosity adjustment can be performed quickly.

Further, according to the third aspect of the invention, the viscosity is adjusted by changing the amount of the solvent in the chemical solution, and the viscosity can be adjusted with a relatively simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic view of a substrate processing apparatus according to an embodiment of the present invention.

FIG. 2 is a partial perspective view near a nozzle in the substrate processing apparatus of FIG.

FIG. 3 is a functional block diagram of a resist viscosity adjusting system in the substrate processing apparatus of FIG. 1;

FIG. 4 is an explanatory diagram showing a relationship between an atmospheric pressure and a viscosity.

FIG. 5 is a flowchart showing a viscosity adjustment procedure in the embodiment of the present invention.

[Explanation of symbols]

 W Substrate TB Correspondence table between atmospheric pressure and viscosity adjustment amount 1 Substrate processing apparatus 10 Spin chuck 12 Coating liquid recovery cup 16 Chamber 20 Exhaust line 32 Air supply device 42 Static pressure sensor 44 Control unit 50 Mixing unit 52 Nozzle 90 Viscosity Total

Claims (4)

[Claims] 1. A substrate processing apparatus for applying a predetermined chemical solution to a substrate to form a predetermined film on the substrate, comprising: (a) a chemical solution supply means for supplying the chemical solution onto the substrate; A substrate processing apparatus comprising: an atmospheric pressure measuring unit that measures an atmospheric pressure near a substrate; and (c) a chemical viscosity adjusting unit that adjusts a viscosity of the chemical according to the atmospheric pressure. 2. The substrate processing apparatus according to claim 1, wherein the chemical solution viscosity adjusting means comprises: (c-1) a storage means for storing in advance a correspondence relationship between the value of the atmospheric pressure and the viscosity adjustment value of the chemical solution. (C-2) for the atmospheric pressure measured by the atmospheric pressure measuring means, a specifying means for specifying a viscosity adjustment value corresponding to the value of the atmospheric pressure from the correspondence, (c-3) by the specifying means A substrate processing apparatus, comprising: a viscosity changing unit configured to change a viscosity of the chemical supplied from the chemical supplying unit to the substrate according to the specified viscosity adjustment value. 3. The substrate processing apparatus according to claim 2, wherein the chemical liquid supply means comprises: (a-1) a raw liquid supply means for supplying a raw liquid of the chemical liquid; and (a-2) a diluent for diluting the raw liquid. Solvent supply means for supplying a solvent, (a-3) mixing means for mixing the stock solution and the chemical solution,
Wherein the viscosity adjustment value is a supply amount of the solvent to the mixing means, and the viscosity changing means, from the solvent supply means, according to the viscosity adjustment value specified by the specifying means. A substrate processing apparatus for changing the supply amount of the solvent to the mixing means. 4. The substrate processing apparatus according to claim 1, wherein: (d) a chemical solution viscosity measuring means for measuring a viscosity of the chemical solution; and (e) a chemical solution viscosity measuring device for measuring the viscosity of the chemical solution. A viscosity feedback control means for feeding back the viscosity value to the chemical liquid viscosity adjusting means.