JP2007305943A - Substrate processor, and substrate processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a film whose film thickness is stable even with chemical whose viscosity is low and is easily changed. <P>SOLUTION: A resist liquid feeder 2 feeds resist liquid to a substrate 12. In the feeding path, a viscosity measuring part 5 measures the viscosity of the resist liquid. The measurement of the viscosity is carried out by measuring a time when a float moving in the path according as the resist liquid is supplied moves in a fixed section. A control unit 8 which has received the result specifies a proper substrate processing revolving speed by referring to a table 31, in which the relationship of a necessary substrate processing revolving speed for forming a film whose film thickness is predetermined and a viscosity evaluation value is stored; and matches the revolving speed of a motor 7 with the above mentioned revolving speed. Thus, it is possible to constantly maintain the film thickness of the film to be formed even when the viscosity of the resist liquid is changed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a substrate processing apparatus that forms a film on a substrate by supplying a chemical solution onto the substrate and rotating the substrate.

  In recent years, the diameter of a semiconductor substrate used for manufacturing an integrated circuit or the like has been increasing. At the same time, there is an increasing demand for the degree of pattern integration on the substrate. Therefore, in a photolithography process of a semiconductor substrate, it is required to form a resist film thinly and uniformly on a large-diameter substrate. For example, it is required to form a resist film with a film thickness of about 1 to 2 μm or less.

In order to form a thin and uniform resist film on a large-diameter substrate in this way, the resist solution used preferably has a low viscosity. This is because, in a resist solution having a high viscosity, the resist solution rises on the substrate due to the viscosity, and it is difficult to spread it thinly on the entire substrate. An example of a substrate processing apparatus that forms a resist film with a low-viscosity chemical solution is, for example, an apparatus described in Patent Document 1 shown in FIG. This apparatus includes a chemical viscosity measuring unit and a solvent supply mechanism for adjusting the chemical viscosity, and can improve the control of the obtained film thickness.
Japanese Patent Laid-Open No. 10-340839 (published on December 22, 1998)

  However, when a low-viscosity resist solution is used, there arises a problem that the thickness of the formed resist film is not constant from day to day.

  This is because the viscosity of the supplied resist solution varies. In general, the resist solution contains a volatile solvent component. The viscosity changes as the solvent component volatilizes. In particular, a low-viscosity resist solution contains a large amount of solvent components, so that the viscosity varies greatly.

  This becomes a problem not only in an apparatus for forming a resist film on a semiconductor substrate but also in an apparatus in general that forms a required film by applying a chemical solution on a substrate.

  In addition, the apparatus described in Patent Document 1 has a problem in that the configuration of the entire processing apparatus system is increased because necessary parts are increased.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a substrate processing apparatus and a substrate processing method capable of forming a film having a uniform predetermined thickness while preventing the influence of fluctuations in chemical viscosity. Is to provide.

  In order to solve the above problems, a substrate processing apparatus according to the present invention supplies a chemical solution onto a substrate and rotates the substrate to form a film on the substrate. Chemical solution supply means for supplying onto the substrate, chemical solution viscosity measuring means for measuring the viscosity of the chemical solution in a route for supplying the chemical solution, and rotation speed adjustment for adjusting the rotation speed of the substrate according to the viscosity of the chemical solution Means.

  According to said structure, a chemical | medical solution viscosity measurement means measures the viscosity of the chemical | medical solution supplied from a chemical | medical solution supply means in the path | route which supplies the said chemical | medical solution. Then, the rotational speed adjusting means adjusts the processing rotational speed of the substrate to an optimal rotational speed in order to obtain a required film thickness according to the viscosity of the chemical solution. As shown in FIG. 4B, a change in the formed film thickness due to a change in the viscosity of the chemical solution can be compensated by the processing rotation speed of the substrate. For this reason, the above-described configuration can prevent the influence of fluctuations in the chemical viscosity.

  If the influence of fluctuations in the chemical liquid viscosity can be prevented, a film having a stable film thickness can be formed even with a low-viscosity chemical liquid whose viscosity tends to fluctuate. If it is a low-viscosity chemical | medical solution, the swelling on the board | substrate by the viscosity of a chemical | medical solution can be prevented, and a uniform and thin film | membrane can be formed. Therefore, according to said structure, there exists an effect that the film | membrane of uniform predetermined thickness can be formed, preventing the influence of the fluctuation | variation of a chemical | medical solution viscosity.

  In addition, in order to solve the above-described problem, the substrate processing method according to the present invention supplies a chemical solution on the substrate and rotates the substrate to form a film on the substrate. A chemical solution supplying step for supplying the chemical solution onto the substrate, a chemical solution viscosity measuring step for measuring the viscosity of the chemical solution in a path for supplying the chemical solution, and a rotation for adjusting the number of revolutions of the substrate according to the viscosity of the chemical solution It includes a number adjustment step.

  According to said structure, there exists an effect similar to the substrate processing apparatus which concerns on this invention.

  In the substrate processing apparatus according to the present invention, the chemical solution viscosity measuring means may further determine the viscosity of the chemical solution based on a time during which a member moving in the route for supplying the chemical solution passes through a certain section in the route. It is preferable to measure.

  The time for which the member in the path of the chemical solution passes through a certain section in the path depends on the moving speed of the member. The moving speed of the member depends on the viscosity of the chemical solution. Therefore, the viscosity of the chemical solution can be measured based on the time for the members in the chemical solution path to pass through a certain section in the route.

  According to said structure, since the viscosity of the chemical | medical solution actually supplied to the said board | substrate is measured, the reliability of the viscosity measurement result is high. At the same time, since it is not necessary to take out a part of the chemical solution for measuring the viscosity of the chemical solution, there is an additional effect that the waste of the chemical solution can be eliminated.

  In the substrate processing apparatus according to the present invention, it is preferable that the member is a float in which an effective weight and an effective area are determined so that the member moves in the path along with the supply of the chemical solution.

  The effective weight is obtained by subtracting the buoyancy of the float in the chemical solution from the weight of the float. The effective area is the maximum value of the horizontal cross-sectional area of the float.

  According to said structure, the said float moves upwards with the pressure received from a fluid at the time of supply of the said chemical | medical solution. In addition, when the supply of the chemical solution is stopped, it moves downward by gravity. Therefore, there is an additional effect that the member can be easily moved in the path of the chemical solution.

  In the substrate processing apparatus according to the present invention, the chemical viscosity measuring means is further disposed on both ends of the fixed section, based on output signals from two sets of sensors that detect the member moving in the path, It is preferable to measure the viscosity of the chemical solution.

  Examples of sensors that can be used include transmission type, reflection type, capacitance detection type, and eddy current type sensors. When using an eddy current type sensor, the material of the member preferably contains metal.

  According to said structure, there exists an effect that the passage time of the said fixed area of the said member can be automatically measured by the output signal from a sensor. Depending on the degree of coloration of the chemical, the sensor can be appropriately selected from a transmission type, a reflection type, a capacitance detection type, and an eddy current type. When using an eddy current type sensor, the material of the member preferably contains metal. This is because an eddy current type sensor detects an eddy current generated by a metal.

  As described above, the substrate processing apparatus according to the present invention adjusts the rotation speed of the substrate according to the chemical solution viscosity measuring means for measuring the viscosity of the chemical solution in the route for supplying the chemical solution, and the viscosity of the chemical solution. Therefore, even if the viscosity of the supplied chemical solution fluctuates, a film having a required film thickness can be formed on the substrate.

  An embodiment of the present invention will be described below with reference to FIGS.

(Main functions of the substrate processing apparatus 1)
FIG. 1 is a block diagram showing the main functions of the substrate processing apparatus 1 according to this embodiment. As shown in the figure, the substrate processing apparatus 1 includes a resist solution supply unit 2 (chemical solution supply unit), a viscosity measurement unit 5 (viscosity measurement unit), a nozzle 6, a motor 7, and a control unit 8 (rotation speed control unit). It has.

  The motor 7 rotates the substrate 12.

  The resist solution supply unit 2 includes a pump 3 and a chemical solution bottle 4 and functions as a chemical solution supply unit. The chemical solution bottle 4 stores a resist solution. The pump 3 pumps up the resist solution in the chemical solution bottle 4 and supplies it to the substrate 12 under pressure. Specifically, the resist solution is supplied from the nozzle 6 to the substrate 12 through the viscosity measuring unit 5.

  The viscosity measuring unit 5 functions as a viscosity measuring unit. As will be described later, the viscosity measuring unit 5 measures the time taken for the members in the viscosity measuring unit 5 to move in a certain section. And the measured value is transmitted to the control part 8 as a viscosity evaluation value.

  The control unit 8 includes a CPU 9 and a memory 10 and functions as a rotation speed adjusting means. The memory 10 stores a table 31. As shown in FIG. 4A, the table 31 shows the correspondence between various values of the viscosity assumed in advance and the processing rotation number of the substrate 12 necessary for obtaining a required film thickness. It is expressed in the form. The viscosity is represented by time as a viscosity evaluation value. This corresponds to the measurement result transmitted from the viscosity measuring unit 5. The control unit 8 specifies the processing rotation number of the substrate 12 necessary for obtaining a required film thickness by referring to the table 31 according to the measurement result transmitted from the viscosity measurement unit 5. Then, the rotational speed of the motor 7 is controlled so as to coincide with the specified processing rotational speed.

  In the above description, the case where the format of the viscosity evaluation value is time has been described, but the present invention is not limited to this. The form of the viscosity evaluation value may be the viscosity itself. If the CPU 9 performs the process of calculating the viscosity from the time taken for the member in the viscosity measuring unit 5 to move in a certain section, the same effect as in the present embodiment can be obtained.

  However, when the format of the viscosity evaluation value is time as in the present embodiment, the processing is simplified because the processing for calculating the viscosity is unnecessary.

  Further, by obtaining the pipe internal volume from the viscosity measuring section 5 to the tip of the nozzle 6 in advance, it becomes possible to perform the feedforward control using the measurement result of the viscosity of the resist solution more strictly. That is, the exact rotation timing at which the resist solution whose viscosity has been measured is supplied onto the substrate 12 can be calculated to control the processing speed of the substrate 12.

(Schematic configuration of the substrate processing apparatus 1)
FIG. 2 is a cross-sectional view showing a schematic configuration of the substrate processing apparatus 1 according to the present embodiment. A schematic configuration of the substrate processing apparatus 1 will be described below with reference to FIG.

  The spin chuck 13 holds the substrate 12 by vacuum suction substantially horizontally. The motor 7 rotates the substrate 12 in a horizontal plane via the rotating shaft 14 and the spin chuck 13.

  The coating liquid recovery cup 15 accommodates the substrate 12 and the spin chuck 13. The coating liquid recovery cup 15 prevents splashing of the surplus resist liquid to the periphery, collects the surplus resist liquid, and guides it to a predetermined coating liquid recovery path, and is made of resin or metal. . A drain hole 16 for waste liquid and disposal is provided at the bottom.

  The chamber 17 completely surrounds the entire coating liquid recovery cup 15 and includes an air supply port 25 and an exhaust port 27. The air supply port 25 is formed above the substrate 12 and is connected to the air supply device 20 via the air supply line 24. The air supply device 20 includes an air supply fan 21, an air supply amount adjusting damper 22, and a filter 23 for the purpose of removing particulates and the like. Then, clean air adjusted to the same constant temperature and humidity as the clean room is supplied from the air supply device 20 through the air supply conduit 24 and the air supply port 25 into the chamber 17. On the other hand, the exhaust port 27 is formed near the bottom of the chamber 17. An exhaust pipe 30 is connected to the exhaust port 27, and air supplied from the air supply port 25 into the chamber 17 is exhausted therefrom. An exhaust amount adjusting damper 29 is provided in the exhaust pipe line 30. The exhaust amount from the exhaust pipe 30 can be adjusted by changing the opening degree of the exhaust amount adjusting damper 29 with respect to the exhaust flow direction by the exhaust damper adjusting motor 28. Thereby, even when the amount of air supplied from the air supply port 25 to the chamber 17 is constant, the atmospheric pressure in the chamber 17 can be adjusted.

  In addition, a window 19 for carrying in and out the substrate 12 is formed in the chamber 17. The window 19 is sealed with a lid 18 except when the substrate 12 is carried in and out. The static pressure sensor 26 is used to detect the atmospheric pressure in the chamber 17. Above the substrate 12, a nozzle 6 for supplying a resist solution to the upper surface of the substrate 12 is disposed.

(Detailed description of the viscosity measuring unit 5)
FIG. 3 is a side view of the periphery of the viscosity measuring unit 5. Hereinafter, the viscosity measuring unit 5 will be described in detail with reference to FIG.

  The viscosity measuring unit 5 is configured to be used also as a floating flow meter. That is, this is a configuration in which a sensor is added to a general floating flow meter, and includes sensors 32 and 33, a float 36, and a tube 37.

  The pipe 37, the arm lower part 35, the nozzle arm 34, and the nozzle 6 are hollow. The resist solution supplied from the arm lower portion 35 by the chemical solution supply means 2 is supplied from the nozzle 6 to the substrate 12 through the viscosity measuring unit 5 and the nozzle arm 34.

  The float 36 is a float used for a floating flowmeter, and is enclosed in a tube 37. The tube 37 is installed in the vertical direction. The resist solution is supplied from below the tube 37. When the resist solution is supplied, the float 36 moves to the upper part of the tube 37 by the pressure of the fluid. When the supply of the resist solution is stopped, the float 36 moves to the lower part of the tube 37 by gravity.

  The sensors 32 and 33 are sensors that detect the passage of the float 36. These are installed on the side of the pipe 37 at a certain interval. The time measurement timer is operated when the float 36 passes in front of the sensor 32 installed at the upper part, and the time measurement timer is stopped when it passes through the sensor 33 installed at the lower part. As a result, the time required for the float 36 to pass through the predetermined section is measured and transmitted to the control unit 8. Alternatively, a signal indicating that each sensor has passed may be transmitted to the control unit 8 as it is, and the time taken for the passage in the control unit 8 may be calculated.

  As the sensors 32 and 33 used at this time, a transmission type sensor, a reflection type sensor, or a capacitance detection type sensor can be used, and may be appropriately selected according to the degree of coloring of the resist solution. 33 need not be the same type of sensor. In addition, if the material of the floating object to be detected includes a metal, an eddy current sensor can also be used.

  In the above description, the case where the viscosity measuring unit 5 is also used as a floating flow meter has been described, but the present invention is not limited to this. It may be combined with another type of flow meter or may not be combined at all. In that case, the float 36 is a float-like member used in a general floating flow meter, or other member, and an effective weight and an effective weight so that the float 36 moves in the tube 37 as the resist solution is supplied. What is necessary is just to set the area.

  More specifically, first, when the chemical liquid is supplied into the path, a differential pressure as shown in Equation 1 is applied to the float 36 existing in the path due to the pressure of the kinetic fluid.

Q = αA√ (2ΔP / ρ) Equation 1
Where Q is the flow rate of the resist solution, α is the outflow coefficient, A is the area of the fluid passage between the float 36 and the tube 37, ρ is the density of the fluid, and ΔP is the differential pressure. .

  Here, the effective weight and effective area of the float 36 are set so that the condition expressed by Equation 2 is satisfied.

aΔPmax>W∧W> aΔPmin Expression 2
Where W is the effective weight of the float, a is the effective area of the float, ΔPmax is the maximum value of the differential pressure upward, and ΔPmin is the minimum value of the differential pressure upward.

  When the floating element receives the largest differential pressure upward, the floating element moves upward because the differential pressure applied to the entire effective area of the floating element is larger than the weight of the floating element. On the other hand, when the floating element receives the smallest differential pressure upward or not at all, the differential pressure applied to the entire effective area of the floating element is smaller than the weight of the floating element, so that the floating element moves downward. . When the float receives the largest differential pressure upward, for example, when supplying the chemical solution, and when the float receives the lowest differential pressure, for example, supply the chemical solution. It is when it stops.

  Each value of ΔPmax and ΔPmin can be calculated from the flow rate in each case using Equation 1 or by actually measuring the differential pressure in each case.

  Accordingly, as in the present embodiment, the float 36 moves to the upper portion of the tube 37 when the resist solution is supplied, and moves to the lower portion of the tube 37 when the supply is stopped.

  However, when the viscosity measuring unit 5 is also used as a flow meter as in the present embodiment, the number of parts of the entire substrate processing apparatus 1 can be suppressed.

(Substrate processing procedure in the substrate processing apparatus 1)
FIG. 5 is a flowchart showing a substrate processing procedure in the substrate processing apparatus 1 according to the present embodiment. Hereinafter, the substrate processing procedure in the substrate processing apparatus 1 will be described based on the adjustment of the processing speed of the substrate 12 with reference to FIG.

In the following, in order to comprehensively explain various examples of the scope of application of the present invention,
(I) adjusting the initial processing rotational speed of the substrate 12 according to the viscosity designated in advance;
(Ii) Before applying the resist solution to the substrate 12, trially discharging the resist solution at the retracted position, and adjusting the processing rotation speed of the substrate 12 from the measurement result of the viscosity at that time,
(Iii) measuring the viscosity of the resist solution in parallel with actually applying the resist solution to the substrate 12, and adjusting the processing speed of the substrate 12 from the result;
It is explained to do all of the above comprehensively. However, in practice, only one of them may be executed, or any combination of a plurality of them may be executed.

  First, the CPU 9 of the substrate processing apparatus 1 checks whether the table 31 is stored on the memory 10 (step S1). If the table 31 is stored, steps S3 to S4 are omitted, and the process proceeds to step S5 (step S2).

  When the table 31 is not stored, the user of the substrate processing apparatus 1 measures the processing rotational speed of the substrate 12 necessary for forming a film having a required thickness with respect to resist solutions having various viscosities. (Step S3). This consists of (i) preparing resist solutions having various viscosities, (ii) performing film forming operations while changing the processing speed of the substrate 12 for each, and (iii) changing the film thickness of the obtained film It can be realized by measuring and verifying with the film thickness measuring instrument 11. For example, if a measurement result as shown in FIG. 4B is obtained, a necessary substrate processing rotation speed can be obtained in order to obtain a predetermined film thickness in resist solutions having various viscosities. Then, the obtained correspondence relationship is stored in the memory 10 of the control unit 8 in the form of a table 31 as shown in FIG. 4A (step S4). The work so far may be performed by a device manufacturer or the like. In addition, the table 31 can be always rewritten to the latest state by performing periodically. In this case, it is necessary to secure a new input reception area on the memory 10.

  When the data input is completed, the substrate processing apparatus 1 starts a series of processes for resist film formation processing (step S5).

  First, the air supply device 20 starts operating before the substrate 12 is carried into the chamber 17, and keeps the environmental temperature and humidity in the chamber 17 thereafter constant.

  After the supply and exhaust of air in the chamber 17 are stabilized, the nozzle 6 is moved to the retracted position, and the resist solution is discharged on a trial basis. The viscosity measuring unit 5 measures the viscosity of the resist solution (step S6).

  The viscosity measuring unit 5 transmits the viscosity evaluation value to the control unit 8. The CPU 9 of the control unit 8 searches the correspondence relationship including the measured viscosity evaluation value on the table 31 on the memory 10 (step S7). If the correspondence including the measured viscosity evaluation value exists on the table 31, the CPU 9 specifies the processing rotational speed of the substrate 12 according to the correspondence. When there is no correspondence including the measured viscosity evaluation value, the correspondence including the closest viscosity evaluation value is referred to, and interpolation (interpolation) or extrapolation of the numerical sequence of the substrate processing rotation speed on the table 31 is performed. To specify the processing speed of the substrate 12. The value specified above is output to the motor 7 as the rotation speed control command value.

  The motor 7 adjusts the rotational speed so as to coincide with the rotational speed control command value (step S8). The substrate 12 is carried into the chamber 17 and held by the spin chuck 13. Then, a resist solution is supplied onto the substrate 12 from the nozzle 6. The supplied resist solution is uniformly applied on the surface of the substrate 12 by the rotation of the substrate 12.

  Next, the CPU 9 checks an interrupt signal for instructing completion of a series of resist solution coating operations (step S9), and determines the presence or absence of the interrupt signal (step S10). If there is no interrupt signal, the pump 3 is driven to supply the resist solution for the next processing, and the process returns to the step of measuring the viscosity of the resist solution (step S6). By repeating such a loop process, when a temporal variation occurs in the viscosity of the resist solution due to volatilization of the solvent component of the resist solution, the processing rotational speed of the substrate 12 is adjusted to an appropriate value following the fluctuation. Can be changed.

  In step S10, if there is an interrupt signal instructing completion, the process exits from such a monitoring and adjustment routine, and a series of operations for applying the resist solution to the substrate 12 is completed.

  In the above description, in order to specify the processing rotational speed of the substrate 12, the correspondence relationship between the viscosity evaluation value and the appropriate processing rotational speed of the substrate 12 has been described as a table. However, the present invention is not limited to this. Absent. The correspondence relationship may be converted into a function using an approximate function. The approximate function here is a function for obtaining the vicinity of the appropriate processing speed of the substrate 12 using the viscosity evaluation value as an argument. Using this function, the control unit 8 can specify the processing rotational speed of the substrate 12 necessary for forming a film having a required film thickness from the viscosity evaluation value received from the viscosity measurement unit 5.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be suitably used in a substrate processing apparatus that forms a thin and uniform film on a large-diameter substrate.

It is a block diagram which shows the principal part function of the substrate processing apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the substrate processing apparatus which concerns on one Embodiment of this invention. It is a side view which shows the structure of the periphery of the viscosity measurement part which concerns on one Embodiment of this invention. (A) is explanatory drawing which shows the structure of the table used in the rotation speed adjustment means based on one Embodiment of this invention, (b) is a board | substrate process rotation speed when changing the viscosity of a resist liquid, It is the graph which showed the relationship with the film thickness of the film | membrane formed. It is a flowchart which shows the procedure of the substrate processing of the substrate processing apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the principal part structure of the substrate processing apparatus which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 2 Resist liquid supply part (chemical solution supply means)
5 Viscosity measuring part (viscosity measuring means)
6 Nozzle 7 Motor 8 Control part (rotational speed control means)
12 Substrate 31 Table 32, 33 Sensor 36 Float

Claims (9)

In the substrate processing apparatus for forming a film on the substrate by supplying a chemical solution onto the substrate and rotating the substrate,
Chemical supply means for supplying the chemical to the substrate;
A chemical viscosity measuring means for measuring the viscosity of the chemical in the path for supplying the chemical,
A substrate processing apparatus comprising: a rotation speed adjusting unit that adjusts the rotation speed of the substrate according to the viscosity of the chemical solution.   The said chemical | medical solution viscosity measuring means measures the viscosity of the said chemical | medical solution based on the time for the member which moves in the path | route which supplies the said chemical | medical solution to pass through the fixed area in the said path | route. The substrate processing apparatus as described.   The substrate processing apparatus according to claim 2, wherein the member is a float whose effective weight and effective area are determined so as to move in the path along with the supply of the chemical solution.   The medicinal solution viscosity measuring means is arranged on both ends of the fixed section and measures the viscosity of the medicinal solution based on output signals from two sets of sensors that detect the member moving in the path. The substrate processing apparatus according to claim 2.   The substrate processing apparatus according to claim 4, wherein the two sets of sensors are transmissive sensors.   The substrate processing apparatus according to claim 4, wherein the two sets of sensors are reflective sensors.   The substrate processing apparatus according to claim 4, wherein the two sets of sensors are capacitance detection type sensors.   5. The substrate processing apparatus according to claim 4, wherein the member includes a metal as a material, and the two sets of sensors are eddy current type sensors. In the substrate processing method of forming a film on the substrate by supplying a chemical solution onto the substrate and rotating the substrate,
A chemical supply step for supplying the chemical onto the substrate;
A chemical solution viscosity measuring step for measuring the viscosity of the chemical solution in a path for supplying the chemical solution;
And a rotation speed adjustment step of adjusting the rotation speed of the substrate in accordance with the viscosity of the chemical solution.

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