JP2000077310A - Coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly form the film thickness of a resist film that is formed on the surface of a wafer over the entire surface by supplying a first amount of coating agent onto a substrate to be treated that rotates at a constant speed and then supplying a second amount of coating agent onto the rotating substrate to be treated. SOLUTION: A resist nozzle 60 is moved to a position nearly directly above the center of a wafer W before rotation being retained by a spin chuck 51, and a specific amount of solvent is dripped from the resist nozzle 60 to thinly cover the entire upper surface of the wafer while the wafer W including the spin chuck 51 is rotated by a motor 52. Then, the rotation of the wafer W including the spin chuck 51 is accelerated to a specific speed for rotating at a constant speed, and then the first, first amount of resist discharge is applied to the wafer W from the resist nozzle 60 via a resist supply pipe 66, and the second, second amount of resist discharge is applied to the wafer W by the resist 60 after a specific amount of time passes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method for applying a coating material such as a resist material onto a substrate to be processed such as a silicon wafer in a semiconductor manufacturing process by photolithography.

[0002]

2. Description of the Related Art Conventionally, as a method of applying a coating material such as a resist material to a substrate such as a silicon wafer, a method called a spin coating method is generally used.

In the spin coating method, a substrate such as a silicon wafer is sucked and held on a disk-shaped holding member called a spin chuck, and a solution-like resist material is discharged almost to the center of the substrate. This is a method of rotating a spin chuck at high speed. By rotating the spin chuck at high speed, a centrifugal force acts on the resist material located at the center, and the resist material diffuses radially outward from the center on the substrate surface by the centrifugal force, and covers the entire substrate surface.
When the high-speed rotation is further continued, the excess resist material is shaken off by centrifugal force, and a thin coating film having a uniform film thickness is formed on the substrate.

[0004]

However, the affinity between the resist material and the wafer W is not always high. Therefore, the resist material supplied to the surface of the wafer W
Forming a thick coating part unevenly on a part of the surface,
Conversely, on a part of the surface of the wafer W, the resist material is repelled, and the coating film may be partially thinned, and the coating film may be non-uniform on the whole surface of the wafer W. When the film thickness of the coating film becomes non-uniform as described above, the quality of semiconductor elements formed on the surface of the wafer W varies, the yield of semiconductor elements decreases, and the production cost per element increases. There was a problem.

The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a coating method capable of forming a resist film formed on the surface of the wafer W to a uniform thickness over the entire surface of the wafer W.

[0006]

According to a first aspect of the present invention, there is provided a coating method comprising: supplying a first amount of a coating material onto a substrate to be processed rotating at a constant speed; Supplying a second amount of the coating agent onto the substrate to be rotated.

According to a second aspect of the present invention, there is provided the coating method according to the first aspect, wherein the second amount is larger than the first amount.

According to a third aspect of the present invention, there is provided the coating method according to the first or second aspect, wherein the first amount is 0.01.
0.1 to 0.1 cc, and the second amount is 0.3 to 0.39.
cc.

According to a fourth aspect of the present invention, in the coating method, a first amount of the coating agent is supplied to the substrate to be processed rotating at a first speed, and the coating method is applied to the substrate to be rotated at the first speed. Supplying a second amount of the coating agent; and accelerating the non-processed substrate at a first acceleration to a second speed.

According to a fifth aspect of the present invention, there is provided the coating method, wherein a first amount of the coating material is supplied onto the substrate to be processed rotating at a first speed, and the substrate is processed at a second speed at a first acceleration. Supplying a second amount of coating agent onto the substrate while accelerating the coating agent to the substrate.

A sixth aspect of the present invention is the coating method according to the fourth or fifth aspect, wherein the second amount is larger than the first amount.

The coating method according to a seventh aspect is the coating method according to the sixth aspect, wherein the first amount is 0.01 to 0.5.
1 cc, and the second amount is 0.3 to 0.39 cc.

According to another aspect of the present invention, there is provided a coating method comprising: supplying a first amount of a coating material onto a substrate to be rotated at a first speed; Supplying a second amount of the coating agent, accelerating the substrate to be processed at a first acceleration to a second speed, detecting the thickness of a coating film on the substrate to be processed, Controlling the time to rotate at the second speed based on the detected film thickness.

According to a ninth aspect of the present invention, in the coating method, a first amount of the coating material is supplied onto the substrate to be rotated at the first speed, and the coating is performed on the substrate to be rotated at the first speed. Supplying a second amount of the coating agent, accelerating the substrate to be processed at a first acceleration to a second speed, detecting the thickness of a coating film on the substrate to be processed, Controlling the time for accelerating from the second speed to the second acceleration based on the detected film thickness.

According to a tenth aspect of the present invention, there is provided a coating method, comprising: supplying a first amount of a coating material onto a substrate to be processed rotating at a first speed; A step of supplying a second amount of the coating agent onto the substrate to be processed while accelerating to a speed, a step of detecting the film thickness of the coating film on the substrate to be processed, and, based on the detected film thickness, Controlling the time to rotate at the second speed.

In the coating method according to the eleventh aspect, a first amount of the coating material may be supplied onto the substrate rotating at a first speed, and the substrate may be rotated at a second speed at a first acceleration. Supplying a second amount of the coating agent onto the substrate to be processed while accelerating up to, and detecting the film thickness of the coating film on the substrate to be processed, and based on the detected film thickness, Controlling the time to accelerate from the second speed with the second acceleration.

According to a twelfth aspect of the present invention, there is provided a coating method, comprising: supplying a first amount of a coating agent onto a substrate to be processed rotating at a first speed; Second
Supplying an amount of the coating agent;
Accelerating to a second speed by acceleration, detecting a film thickness of the coating film on the substrate to be processed, and a second acceleration further accelerating from the second speed based on the detected film thickness And a step of controlling

According to a thirteenth aspect of the present invention, in the coating method, a first amount of the coating material is supplied onto the substrate to be rotated at a first speed, and the substrate is rotated at a second speed at a predetermined acceleration. Supplying a second amount of the coating agent onto the substrate to be processed while accelerating up to, and detecting the film thickness of the coating film on the substrate to be processed, and based on the detected film thickness, Controlling a second acceleration further accelerating from the second speed.

In the coating method according to the first aspect, the coating material is supplied in a plurality of times while the substrate to be processed is rotated at a constant speed, and the first amount of the coating material supplied first is reduced. It functions as a surfactant that improves the affinity between the surface of the substrate to be processed and the coating agent, and the second amount of the coating agent supplied from the second time on becomes familiar with the surface of the substrate to be processed and becomes slippery. Is uniformly diffused over the entire surface of the substrate to be processed, and a coating film having a uniform thickness is obtained.

In the coating method according to the second aspect, in addition to the effect of the coating method according to the first aspect, since the second amount is set to be larger than the first amount, the spread of the coating liquid becomes good. The film thickness of the coating film can be controlled with higher accuracy.

According to a third aspect of the present invention, the first amount is 0.01 to 0.1 cc and the second amount is 0.3 cc.
Since the thickness is set to 0.39 cc, the spread of the coating liquid is improved, and the thickness of the coating film can be controlled with higher accuracy.

According to a fourth aspect of the present invention, in addition to the effect of the first aspect, the substrate to be processed is accelerated to the second speed at the first acceleration after the supply of the coating agent, and the strong centrifugation is performed. Since a force is generated to diffuse the coating agent, the coating film can be more reliably thinned.

According to a fifth aspect of the present invention, in addition to the effect of the first aspect, the substrate to be processed is accelerated to the second speed at the first acceleration after the first supply of the coating agent to be supplied is completed. Since the second application agent is supplied while the strong centrifugal force is being generated to diffuse the application agent, the coating film can be more reliably made thin.

According to the coating method of the sixth aspect, in addition to the effect of the coating method of the fourth or fifth aspect, since the second amount is larger than the first amount, the spread of the coating liquid is increased. As a result, the film thickness of the coating film can be controlled with higher accuracy.

According to a seventh aspect of the present invention, the first amount is 0.01 to 0.1 cc and the second amount is 0.3 cc.
Since the thickness is set to 0.39 cc, the spread of the coating liquid is improved, and the thickness of the coating film can be controlled with higher accuracy.

According to the coating method of the present invention, in addition to the effect of the coating method of the first aspect, the thickness of the coating film on the substrate to be processed is detected, and the second film thickness is determined based on the detected thickness. Since the rotation time at the speed is controlled, the film thickness of the coating film can be managed with higher accuracy. In the coating method according to the ninth aspect, in addition to the effects of the coating method according to the first aspect, the thickness of the coating film on the substrate to be processed is detected, and the acceleration is performed at the second acceleration based on the detected thickness. Since the time is controlled, the film thickness of the coating film can be managed with higher precision. Claim 10
In the coating method described above, a second amount of a coating agent is supplied onto the substrate to be processed while accelerating the substrate to be processed at a first acceleration to a second speed, and a coating film on the substrate to be processed is Since the film thickness is detected and the time for rotating at the second speed is controlled based on the detected film thickness, the film thickness of the coating film can be managed with higher accuracy.

[0027] According to the eleventh aspect, in the coating method, the first aspect is provided.
In addition to the effect of the coating method 2, the film thickness of the coating film on the substrate to be processed is detected, and the time for accelerating at the second acceleration is controlled based on the detected film thickness. The thickness of the film can be controlled.

According to a twelfth aspect of the invention, there is provided the coating method according to the first aspect.
In addition to the effect of the coating method described above, the thickness of the coating film on the substrate to be processed is detected, and the second acceleration that further accelerates from the second speed is controlled based on the detected thickness. The thickness of the coating film can be controlled with high accuracy.

[0029] In the coating method according to the thirteenth aspect, the first aspect of the present invention is the first aspect.
In addition to the effect of the coating method of 4, the second amount of the coating material is supplied onto the substrate while accelerating the substrate to be processed at the first acceleration to the second speed, so that the coating film can be more reliably formed. It can be thinned.

[0030]

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

FIG. 1 shows a semiconductor wafer (hereinafter, referred to as a COT) provided with a resist coating unit (COT) according to an embodiment of the present invention.
FIG. 1 is a plan view showing the entire coating and developing processing system 1 of “wafer”).

In the coating and developing system 1, a plurality of wafers W as objects to be processed are loaded into and unloaded from the system in units of, for example, 25 wafer cassettes CR. A cassette station 10 for loading and unloading, a processing station 11 in which various single-wafer processing units for performing predetermined processing on the wafers W one by one in a coating and developing process are arranged at predetermined positions in multiple stages, and An interface unit 12 for transferring a wafer W to and from an exposure apparatus (not shown) provided adjacent to the processing station 11 is integrally connected. In this cassette station 10,
At the position of the positioning projection 20a on the cassette mounting table 20,
A plurality of, for example, up to four wafer cassettes CR are placed in a line in the X direction with their respective wafer entrances facing the processing station 11, and the wafers stored in the cassette arrangement direction (X direction) and in the wafer cassette CR are arranged. The wafer carrier 21 movable in the wafer arrangement direction of W (Z direction; vertical direction) selectively accesses each wafer cassette CR.

This wafer transfer body 21 is rotatable in the θ direction, and a third
Access to the processing unit group G ₃ of the multi-stage unit section disposed in the alignment unit (ALIM) and an extension unit (EXT).

The processing station 11 is provided with a vertical transfer type main arm 22 having a wafer transfer device.
All the processing units are arranged in multiple stages around one or more sets.

FIG. 2 is a front view of the coating and developing system 1.

In the first processing unit group G ₁ , the cup C
Two spinner type processing units, for example, a resist coating unit (COT) and a developing unit (DEV), which perform a predetermined process by placing the wafer W on the spin chuck in the P, are stacked in two stages from the bottom. In the second processing unit group G _2, two spinner-type processing units, for example, the resist coating unit (COT) and a developing unit (D
EV) are stacked in two stages in order from the bottom. These resist coating units (COT) are preferably arranged in the lower stage as described above because drainage of the resist solution is troublesome both mechanically and in terms of maintenance. However, it is of course possible to appropriately arrange the upper stage as needed.

FIG. 3 is a rear view of the coating and developing system 1.

In the main arm 22, a wafer transfer device 46 is provided inside the cylindrical support 49 so as to be able to move up and down in the vertical direction (Z direction). The cylindrical support 49 is connected to a rotation shaft of a motor (not shown), and is rotated integrally with the wafer transfer device 46 about the rotation shaft by the rotation driving force of the motor, whereby the wafer transfer is performed. The device 46 is rotatable in the θ direction. Note that the cylindrical support 49 may be configured to be connected to another rotating shaft (not shown) rotated by the motor.

The wafer transfer device 46 is provided with a plurality of holding members 48 movable in the front-rear direction of the transfer base 47, and these holding members 48 transfer the wafer W between the processing units. Is possible.

Further, as shown in FIG. 1, in this coating and developing processing system 1, five processing unit groups G ₁ , G ₂ , G
₃ , G ₄ , G ₅ can be arranged, and the multi-stage units of the first and second processing unit groups G ₁ , G ₂ are arranged on the system front (front side in FIG. 1) side, and the third processing unit multistage unit group G ₃ are cassette station 10
, And the multi-stage unit of the _fourth processing unit group G ₄ is disposed adjacent to the interface unit 12,
Multistage unit of the fifth processing unit group G ₅ is capable of being disposed on the rear side.

As shown in FIG. 3, in the third processing unit group G ₃ , an oven-type processing unit for performing a predetermined process by placing the wafer W on a holding table (not shown), for example, a cooling system for performing a cooling process Unit (COL), adhesion unit (AD) for performing so-called hydrophobic treatment for improving the fixability of resist, alignment unit (ALIM) for positioning, extension unit (EXT), heat treatment before exposure processing Prebaking unit (PREBAKE) for performing heat treatment and postbaking unit (POBAKE) for performing heat treatment after exposure processing
Are, for example, stacked in eight stages from the bottom. Even the fourth processing unit group G _4, oven-type processing units, for example, a cooling unit (COL), an extension and cooling unit (EXTCOL), extension unit (EXT), a cooling unit Bok (CO
L), a pre-baking unit (PREBAKE) and a post-baking unit (POBAKE) are stacked in order from the bottom, for example, in eight stages.

As described above, the cooling unit (COL) and the extension cooling unit (EXTCOL) having a low processing temperature are arranged at the lower stage, and the baking unit (PREBAKE), the post-baking unit (POBAKE) and the adhesion having a high processing temperature are arranged. By arranging the units (AD) in the upper stage, thermal mutual interference between the units can be reduced. Of course, a random multi-stage arrangement may be used.

As shown in FIG. 1, the interface unit 12
In the depth direction (X direction), the processing station 11
But has a smaller size in the width direction (Y direction). A portable pickup cassette CR and a stationary buffer cassette BR are arranged in two stages at the front of the interface unit 12, while a peripheral exposure device 23 is arranged at the rear, and a central exposure unit is further arranged at the center. Is provided with a wafer carrier 24. This wafer carrier 24
Moves in the X and Z directions to access both cassettes CR and BR and the peripheral exposure device 23.

The wafer transfer body 24 is also rotatable in the θ direction, and includes an extension unit (EXT) provided in the multi-stage unit of the fourth processing unit group G ₄ on the processing station 11 side and an adjacent exposure unit. The wafer delivery table (not shown) on the apparatus side can also be accessed.

In the coating and developing system 1, the multi-stage unit of the _fifth processing unit group G5 shown by the broken line in FIG. 1 can be arranged on the back side of the main arm 22 as described above. multistage unit of the processing unit group G ₅ is
It is movable in the Y direction along the guide rail 25. Therefore, even if this is provided fifth as illustrated multistage unit of the processing unit group G ₅ of, by moving along the guide rail 25, the space portion can be secured, behind the main arm 22 Maintenance work can be performed easily.

Next, the resist coating unit (COT) according to this embodiment will be described. FIG. 4 is a schematic sectional view of the resist coating unit (COT) according to the present embodiment.

An annular cup C # is provided at the center of the resist coating unit (COT), and a spin chuck 51 is provided inside the cup C #. The spin chuck 51 is rotationally driven by a drive motor 52 in a state where the wafer W is fixedly held by vacuum suction.

The drive motor 52 is disposed in an opening 50a provided in the unit bottom plate 50 so as to be able to move up and down, and a cap-like flange member 53 made of, for example, aluminum.
Lifting drive means 5 comprising, for example, an air cylinder
4 and the lifting guide means 55.

A resist nozzle 60 for discharging a resist liquid as a coating liquid onto the surface of the wafer W is detachably attached to a tip of a resist nozzle scan arm 61 via a nozzle holder 62. The resist nozzle scan arm 61 is attached to the upper end of a vertical support member 64 that can move horizontally on a guide rail 63 laid in one direction (Y direction) on the unit bottom plate 50, and is not shown in the Y direction. Vertical support member 6 by drive mechanism
4 and moves in the Y direction.

FIG. 5 is a schematic plan view of a resist coating unit (COT) according to the present embodiment.

The resist nozzle scan arm 61 can also be moved in the Χ direction perpendicular to the Y direction in order to selectively mount the resist nozzle 60 in the resist nozzle standby section 65, and is moved in the Χ direction by a Χ direction driving mechanism (not shown). Can also move.

Further, in the resist nozzle standby section 65, the discharge port of the resist nozzle 60 is inserted into the port 65a of the solvent atmosphere chamber, and is exposed to the solvent atmosphere inside, so that the resist liquid at the tip of the resist nozzle 60 solidifies or deteriorates. Not to be. Further, a plurality of resist nozzles 60,
Are provided, and the resist nozzles 60 can be used properly according to the type and viscosity of the resist solution.

Further, a thinner nozzle 60 a is provided adjacent to the resist nozzle 60.

A thinner supply system (not shown) is connected to the thinner nozzle 60a, and a pre-wet is performed by dropping a solvent from the thinner nozzle 60a onto the wafer W as described later.

Further, on the guide rail 63, a vertical support member 6 for supporting the resist nozzle scan arm 61 is provided.
In addition to the vertical support member 4, a vertical support member 71 that supports the rinse nozzle scan arm 70 and is movable in the Y direction is also provided.

The rinsing nozzle scan arm 70 is moved by the Y-direction drive mechanism (not shown) to the rinsing nozzle standby position (the position indicated by the solid line) set on the side of the cup CP and the semiconductor wafer W mounted on the spin chuck 51. It is configured to translate or linearly move between a rinsing liquid discharge position (a position indicated by a dotted line) set immediately above the peripheral portion.

As shown in FIG. 4, the resist nozzle 60
Is connected via a resist supply pipe 66 to a resist liquid supply mechanism disposed in the lower chamber of the resist coating unit (COT).

FIG. 6 is a block diagram showing a control system of the resist coating unit (COT) according to the present embodiment. As shown in FIG. 6, this resist coating unit (CO
In T), the drive motor 5 for rotating the spin chuck 51
2, and a resist supply system for supplying a resist to the resist nozzle 60 is connected to the control unit 100, respectively.
The control unit 100 controls the entire system.

Next, the operation of the coating and developing system 1 configured as described above will be described.

FIG. 7 is a flowchart showing steps in the case where a coating process is performed in the resist coating unit (COT) according to the present embodiment, and FIG. 8 is a timing chart showing the steps. 9 to 16 are perspective views (a) and cross-sectional views (b) schematically showing operations performed in each step.
It is.

The resist coating unit (CO
T), the wafer W is taken out of the wafer cassette CR and transported by the main arm 22 to the resist coating unit (CO).
Access within T). Thereafter, the following resist coating process is started.

First, the main arm 22 delivers the wafer W to a lifter (not shown) of the spin chuck 51 in the coating unit (COT), and sets the wafer W on the spin chuck 51 by lowering the lifter (not shown). Step 1 / time t ₀ ). Next, pre-wetting is performed on the upper surface of the wafer W (Step 2). This pre-wet is a process for thinning the solvent over the entire upper surface of the wafer W to improve the familiarity between the resist and the upper surface of the wafer W, and is performed as follows.

First, the resist nozzle scan arm 61 moves to move the resist nozzle 60 to a position almost directly above the center of the wafer W before rotation held by the spin chuck 51. Next, the motor 52 is driven to start and accelerate the rotation of the wafer W together with the spin chuck 51 (time t).
₁ ~t _2). The wafer W is in a state of being rotated, is dropped a predetermined amount of the solvent from the resist nozzle scanning arm 61 distal end of the resist nozzle 60 to the adjacent arranged thinner nozzle 60a (time t ₃ ~t _4). As shown in FIG. 9, the dropped solvent is diffused outward in the radial direction of the wafer W by the centrifugal force acting on the wafer W, and instantly thinly covers the entire upper surface of the wafer W. The excess solvent is shaken off by centrifugal force and removed. When the pre-wet is completed, the rotation of the wafer W is stopped once (time t _{6 to} t ₇ ). Note that the process may shift to the subsequent resist coating process while the rotation of the wafer W is continued after the pre-wetting.

Following the pre-wet, the following resist coating step is performed.

[0065] First, to start the rotation of the wafer W by the spin chuck 51 by driving the motor 52, a predetermined speed, that is accelerated to the first speed (Step 3 / time t ₇ ~
t _8).

The first speed at this time is a speed capable of diffusing the resist discharged to the center of the wafer W in the radial direction outward and generating a centrifugal force sufficient to shake off and remove excess resist. It is.

The value of the first speed is a so-called design item that varies depending on the viscosity and type of the resist, the diameter of the wafer W, the temperature and humidity at the time of application, and cannot be uniquely specified. However, as an example,
This first speed is between 2000 and 4000 rpm. p. m. Is preferable.

Here, the upper limit of the preferred range of the first speed is set to 4000 r.p.m. p. m. The reason for this is that if the first speed exceeds the upper limit, volatilization of a small amount of the resist discharged at the first time progresses, and the resist discharged at the second time does not spread. .

On the other hand, the lower limit of the preferable range of the first speed is set to 2000 rpm. p. m. The reason is that when the first speed is lower than the lower limit value, the second discharge is performed at the same rotation speed, so that the resist discharged at the second time does not spread, and uniformity of film thickness can be obtained. This is because there is no adverse effect.

[0070] After the rotational speed of the wafer W is now rotated at a constant speed at a first speed (Step 4), the time t9 ~t ₁₀
, A first resist discharge is performed (step 5).

The first resist discharge amount, that is, the first amount, improves the slip and diffusivity of the resist discharged in the subsequent second resist discharge with respect to the upper surface of the wafer W and makes the thickness of the coating film uniform. It is an amount that can be converted

The value of the first amount is a so-called design item, and cannot be uniquely specified. However, as an example, the first amount is preferably in the range of 0.01 to 0.1 cc. .

The reason why the upper limit of the preferable range of the first amount is set to 0.1 cc is that if the first amount exceeds the above upper limit, the amount of the resist discharged at the second time becomes small. This is because there is an adverse effect that the resist does not spread to the outer periphery of the wafer.

On the other hand, the lower limit of the preferable range of the first amount is set to 0.01 cc. When the first amount is lower than the lower limit, the first resist discharge amount is small, and
This is because there is an adverse effect that the resist to be discharged the second time does not spread.

This first resist discharge is performed for a time period from t _{9 to} t ₉
Do over ₁₀ . This time t _{9 to} t ₁₀ , that is, the first
Is a so-called design item and cannot be uniquely specified, but as an example, the first time is preferably in the range of 0.01 to 0.1 second.

The reason why the upper limit of the preferable range of the first time is set to 0.1 second is that if the first time exceeds the upper limit, the discharge rate (speed) is determined. This is because the amount of the second ejection becomes small, and the above-mentioned phenomenon, that is, the resist does not spread to the outer periphery of the wafer occurs.

On the other hand, the reason why the lower limit of the preferable range of the first time is set to 0.01 second is that if the first time falls below the lower limit, the discharge rate (speed) is determined.
This is because the first discharge amount decreases, and the resist discharged in the second discharge does not spread to the outer periphery of the wafer, which causes a problem.

The resist discharged in the first resist discharge is discharged near the center of the wafer W as shown in FIGS. 10 to 11, is diffused outward in the radial direction of the wafer W by centrifugal force, and Spreads horizontally as thickness decreases. Then, the resist discharged in the first resist discharge partially covers the vicinity of the center of the wafer W as shown in FIG.

[0079] After then resist discharge of the first is completed a predetermined time t ₁₀ ~t ₁₁ elapses, the resist ejection of the second to be described below.

Here, the time t _{10 to} t ₁₁ between the first resist discharge and the second resist discharge is a time capable of sufficiently diffusing the resist discharged by the first resist discharge onto the upper surface of the wafer W. is there.

The time t _{10 to} t ₁₁ is a so-called design item, and cannot be uniquely specified. However, for example, the time t _{10 to} t ₁₁ during this time is 0.1 to 0.1.
A range of 5 seconds is preferred.

The reason why the upper limit of the preferable range of the time t _{10 to} t ₁₁ during this time is set to 0.5 second is that if the time during this time exceeds the above upper limit, the resist discharged for the first time will be removed from the wafer. This is because volatilization proceeds due to the rotation, and the resist discharged at the second time does not spread to the outer periphery of the wafer.

On the other hand, the lower limit of the preferable range of the time during this period is set to 0.1 second. If the time during this period is less than the above lower limit, the second discharge is performed before the resist discharged for the first time spreads to some extent. This is because, since the resist is discharged for the second time, there is an adverse effect that the film thickness cannot be made uniform.

After a lapse of time t _{10 to} t ₁₁ , a second resist discharge described below is performed (step 6).

The second resist discharge is a step of discharging the remaining amount of the first resist discharge amount of the entire resist discharge amount, that is, the second amount.

The value of the second amount is a so-called design item, and cannot be uniquely specified. However, for example, the second amount is preferably in the range of 0.3 to 0.39 cc. .

The reason why the upper limit of the preferable range of the second amount is set to 0.39 cc is that when the second amount exceeds the upper limit, the total discharge amount of the resist is 0.5 cc.
This is because the first discharge amount becomes 0.1 cc or more, which causes a problem that the resist cannot be uniformly applied to the outer periphery of the wafer.

On the other hand, the lower limit of the preferable range of the second amount is set to 0.3 cc. When the second amount is lower than the lower limit, the total discharge amount of the resist is 0.4 cc. This is because the amount of the second discharge becomes small, and there is a possibility that the resist may not be applied to the outer periphery of the wafer.

The second resist ejection is performed for a predetermined time, that is, for a second time.

The second time t _{11 to} t ₁₂ is a so-called design item, and cannot be uniquely specified. However, as an example, the second time is 0.3 to 0.3.
A range of 9 seconds is preferred.

The reason why the upper limit of the preferable range of the second time is set to 0.39 seconds is that if the second time exceeds the upper limit, the current discharge rate (speed) becomes 1 ml / sec.
c. Therefore, the amount of discharge in the first discharge decreases, and the resist discharged in the second discharge does not uniformly spread to the outer periphery of the wafer.

On the other hand, the reason why the lower limit of the preferable range of the second time is set to 0.3 second is that when the second time falls below the lower limit, the present discharge rate becomes 1 ml / sec. Therefore, the first discharge amount increases, and the second resist is discharged before the first discharge amount spreads to a certain extent, which causes a problem that a uniform film cannot be obtained. By performing the second resist discharge, the entire resist discharge amount for one wafer W is discharged onto the wafer W.

After the lapse of the second time t ₁₁ -t ₁₂ , the wafer W
The constant rotation until the time t ₁₃ in the first speed is continued.

The resist discharged by the second resist discharge is discharged onto the resist thin film formed by the first resist discharge as shown in FIG. At this time, the resist discharged for the second time slides on the thin film formed by the first discharge and diffuses in the horizontal direction as shown in FIG. Therefore, as shown in FIGS. 14 and 15, the resist discharged for the second time is quickly diffused to the vicinity of the outer peripheral edge of the wafer W, and covers the entire upper surface of the wafer W. Thickness with vertical thickness of the resist is decreased at a constant speed rotation until then time t ₁₃ becomes thin and the film thickness is made uniform. Then, excess resist is shaken off by centrifugal force to form a thin coating film having a uniform film thickness (FIG. 16).

As described above, in the coating unit according to the present embodiment, the resist discharging step of discharging the resist onto the rotating wafer W is divided into two steps, and the resist is discharged onto the upper surface of the rotating wafer W at an appropriate timing. I do. Therefore, the resist discharged on the upper surface of the wafer W in the first discharge serves to improve the slip and diffusion of the resist discharged in the second discharge. As a result, the resist discharged for the second time is quickly diffused outward in the radial direction of the wafer W on the resist thin film formed by being discharged for the first time, and combined with the resist discharged for the first time. A uniform and thin resist film is formed over the entire upper surface of W.

The present invention is not limited to the above embodiment.

Therefore, for example, in the above-described embodiment, the description has been made of the example of applying the resist to the silicon wafer W for manufacturing the semiconductor element. Needless to say, the present invention can be applied.

In this embodiment, the pre-wet is performed. However, in the present invention, the resist discharged at the first time has the same function as the solvent supplied in the pre-wet. Good.

(Examples) Examples of the present invention will be described below.

Example 1 In this example, a coating process was performed using the coating unit described in the first embodiment.

The processing conditions were as shown below.

Step Time (sec) Rotation speed (rpm) Acceleration (rpm / sec) 2 1.00 3 to 4 1.0 2000 10000 5 0.1 3200 10000 Interval between 5 and 6 0.1 3200 10000 6 0.3 3200 10000 725 3000 10000 Discharge volume 0.4ml Discharge speed 1.0ml / sec Pump Millipore pump Model rainbow (MILLIPORE) Air operation valve Model X-25 (CKD) Chemical solution PFI-38A4 (viscosity) (3cP / manufactured by Sumitomo Chemical Co., Ltd.) When the film thickness of the wafer coated under the above conditions was measured as follows, the following measurement results were obtained.
FIG. 17 is a graph of this measurement result. In the film thickness measurement, one sample was extracted from one lot of the product, and measured at 39 places of the sample. The measurement device used was Nanospec N-5100-L12 (manufactured by Nanometrics Japan).

Measurement points 39 places Minimum value 5606 (angstrom) Maximum value 5636 (angstrom) Difference 30 (angstrom) Average value 5621.62 (angstrom) SD 8.23 3 sigma 24.66 As shown in the above results, the film thickness The difference between the thinnest portion and the thick portion is 30 Å, the film thickness is thin, and the distribution is extremely uniform.

It is also shown that a small amount of liquid is dispensed at a large discharge rate (speed), which leads to an effect of reducing the throughput.

Example 2 In this example, a coating process was performed under the following processing conditions.

Step Time (sec) Number of revolutions (rpm) Acceleration (rpm / sec) 2 1.00 3 to 4 1.0 2000 10000 5 0.1 3200 10000 Interval between 5 and 6 0.1 3200 10000 6 0.3 3200 10000 7 25 3000 10000 Discharge volume 0.4ml Discharge speed 1.0ml / sec Pump Millipore pump Model rainbow (MILLIPORE) Air operation valve Model X-25 (CKD) Chemical solution PFI-38A4 (viscosity) (3cP / manufactured by Sumitomo Chemical Co., Ltd.) When the film thickness of the wafer coated under the above conditions was measured as follows, the following measurement results were obtained.
FIG. 18 is a graph of the measurement result. In the film thickness measurement, one sample was extracted from one lot of the product, and measured at 39 places of the sample. The measurement device used was Nanospec N5100-L12 (manufactured by Nanometrics Japan).

Measurement points 39 points Minimum 5566 (angstrom) Maximum 5590 (angstrom) Difference 24 (angstrom) Average 5578.38 (angstrom) SD 7.293 3 sigma 21.86 As shown in the above results, the film thickness The difference between the thinnest part and the thick part is 24 Å, the film thickness is thin, and the distribution is extremely uniform.

It is also shown that a small amount of liquid is dispensed at a high discharge rate (speed), which leads to a reduction in throughput.

Example 3 In this example, a coating process was performed under the following processing conditions.

Step Time (sec) Speed (rpm) Acceleration (rpm / sec) 2 1.00 3 to 4 1.0 2000 10000 5 0.1 3200 10000 Interval between 5 and 6 0.1 3200 10000 6 0.4 3200 10000 725 3000 10000 Discharge volume 0.5ml Discharge speed 1.0ml / sec Pump Millipore pump Model rainbow (MILLIPORE) Air operation valve Model X-25 (CKD) Chemical solution PFI-38A4 (viscosity) (3cP / manufactured by Sumitomo Chemical Co., Ltd.) When the film thickness of the wafer coated under the above conditions was measured as follows, the following measurement results were obtained.
FIG. 19 is a graph of the measurement result. In the film thickness measurement, one sample was extracted from one lot of the product, and measured at 39 places of the sample. The measurement device used was Nanospec N5100-L12 (manufactured by Nanometrics Japan).

Measurement points 39 points Minimum value 5363 (angstrom) Maximum value 5397 (angstrom) Difference 34 (angstrom) Average value 5383.51 (angstrom) SD 9.92 3 sigma 29.75 As shown in the above results, the film thickness The difference between the thinnest portion and the thick portion is 34 Å, the film thickness is thin, and the distribution is extremely uniform.

It is also shown that a small amount of liquid is dispensed at a high discharge rate (speed), which leads to a reduction in throughput.

(Comparative Example) In order to compare the effect of the present invention with a resist film obtained by a conventional coating method, a conventional coating method, that is, a wafer W was sucked and held on a spin chuck, followed by pre-wetting, Thereafter, a predetermined amount of a resist solution was supplied to the upper surface of the wafer W by one discharge, and then the resist solution was rotated at a high speed to form a resist film. When the film thickness of this resist film was measured by the same apparatus as in the above example, the difference between the maximum value and the minimum value of the film thickness was 60 Å.

(Second Embodiment) Hereinafter, a coating unit according to a second embodiment of the present invention will be described. In addition,
The description of the same parts as those in the first embodiment will be omitted.

In the coating unit according to this embodiment, the resist is discharged twice on the wafer W rotating at a constant speed at the first speed, and then the resist is accelerated at a first acceleration and the resist on the wafer W is accelerated. The film thickness is made uniform and the film thickness is reduced.

FIG. 17 is a flowchart in the case of applying a resist using the application unit according to the present embodiment.
FIG. 18 is a timing chart when a resist is applied using the same application unit.

Hereinafter, a procedure for performing resist coating using the coating unit according to the present embodiment will be described.

As shown in FIG. 17, in the coating unit according to the present embodiment, the wafer W rotating at a constant speed at the first speed is rotated twice before and after times t _{8 to} t ₉ and times t _{11 to} t _12. The resist is discharged separately (steps 5 and 6).

Thereafter, the coating unit according to the present embodiment is rapidly accelerated from time t'13 to t'14 (step 7).

The acceleration at this time, ie, the first acceleration, is such that the resist liquid discharged to the center of the wafer W is diffused outward in the radial direction, and at the same time, excess resist liquid is shaken off and removed. This is a speed capable of generating a centrifugal force sufficient to diffuse the resist and make it thinner.

The value of the first acceleration is a so-called design item that differs depending on the viscosity and type of the resist solution, the diameter of the wafer W, the temperature and humidity at the time of application, and cannot be uniquely specified. However, as an example, the first acceleration is 8000 to 50,000 r.p.m. p.
m. / Sec. Is preferable.

Here, the upper limit of the preferable range of the first acceleration is 50,000 r.p.m. p. m. / Sec. The reason for this is that if the first acceleration exceeds the upper limit, a problem arises that the spin motor itself does not operate normally.

On the other hand, the lower limit of the preferable range of the first acceleration is 8000 r.p.m. p. m. / Sec. The reason is that if the first acceleration falls below the lower limit, the resist discharged at the first time is applied to the wafer but has not yet reached the predetermined number of revolutions. Not uniform,
This is because of the disadvantage.

The acceleration of the first acceleration causes the time t'13 to
At t'14, the rotation speed is increased to a predetermined speed, that is, the second speed R.
₃ r. p. m. Up to This second speed R
₃ r. p. m. Is continued during the time T'14～t ₁₅ a constant speed in (Step 8), decelerated over the time t ₁₅ ~t ₁₆ thereafter (step 9), the coating is terminated when stopped (step 10).

In the coating unit according to the present embodiment, the first
After the resist is divided into two portions and discharged onto the wafer W rotating at a constant speed at a constant speed, the rotational speed of the wafer W is further increased at an accelerated rate. Since the thickness is made uniform and the thickness is reduced, a thinner and more uniform resist film can be obtained.

In this embodiment, the resist is discharged twice before and after the wafer W rotated at a constant speed at the first speed. However, the resist may be discharged when the rotation speed of the wafer W is accelerated. .

(Third Embodiment) Hereinafter, a coating unit according to a third embodiment of the present invention will be described. In addition,
The description of the same parts as those in the first and second embodiments will be omitted.

In the coating unit according to this embodiment, after the resist is discharged twice on the wafer W rotating at a constant speed at the first speed, the thickness of the resist film formed on the wafer W is reduced. And based on the detected film thickness, a first
By controlling the rotation time at the second speed after acceleration from the speed, the thickness of the resist film on the wafer W can be made uniform and thin.

FIG. 22 is a block diagram showing a control system of the coating unit according to the present embodiment. As shown in FIG. 22, in the coating unit according to the present embodiment, the spin chuck 5
A sensor S is disposed above the wafer W held in the position 1, and detects the thickness of the coating film on the upper surface of the wafer W. This sensor S is a motor 5 for rotating the spin chuck 51.
2 and the resist supply system are connected to the control unit 100, and are controlled by the control unit 100.

The sensor S used in the coating unit of this embodiment is not particularly limited as long as it can detect the thickness of the resist film formed on the wafer W. For example, a known sensor such as a sensor that measures optically may be used.

Hereinafter, a procedure for performing resist coating using the coating unit according to the present embodiment will be described.

FIG. 23 is a flowchart in the case of applying a resist using the application unit according to the present embodiment.

In the case of performing the resist coating on the wafer W using the coating unit according to the present embodiment, the resist is discharged twice on the wafer W rotated at a first speed at a constant speed (steps 5 and 6). Thereafter, the vehicle is accelerated at the first acceleration (Step 7), and is rotated at a constant speed at the second speed (Step 8).

Next, the thickness of the resist coating film formed on the upper surface of the wafer W is checked (step 9). Specifically, the film thickness of the resist film is detected by the above-described sensor S, and it is determined whether or not the film thickness has been reduced to an appropriate range (step 10), and the subsequent processing is performed based on the result. adjust.

That is, when the detected film thickness is equal to or less than the upper limit of the appropriate range, the rotation speed is reduced as it is (step 1).
1) The resist coating step ends (step 12).

On the other hand, if the detected film thickness exceeds the upper limit of the appropriate range, the time for constant speed rotation at the second speed is adjusted (step 12), and this constant speed rotation is continued (step 12). 8) To make the thickness of the resist coating uniform and to make it thinner.

Then, the film thickness of the coating film is checked again (step 9). If the film thickness becomes lower than the upper limit, the process is terminated at a reduced speed (steps 11 and 13). Steps 12 and 8 to 10 are repeated, and the operations of steps 12 and 8 to 10 are repeated until the film thickness falls within the appropriate range.

According to the method of the present embodiment, while detecting the film thickness of the resist film, the time for rotating at the second speed is controlled based on the detected film thickness. Can be planned.

In this embodiment, the time for the constant speed rotation at the second speed is controlled based on the film thickness detected after the constant speed rotation at the second speed accelerated after the resist discharge. The film thickness is detected after the ejection, and the time for accelerating from the first speed to the second speed is controlled based on the detected film thickness, or the film is further accelerated from the second speed at the second acceleration, The acceleration time at this time may be controlled. Further, the second acceleration itself at this time may be controlled.

Further, in this embodiment, the pre-wet is performed on the wafer W before the resist is discharged. However, the pre-wet may be omitted.

[0141]

As described above in detail, according to the first aspect of the present invention, the coating material is supplied in plural times while the substrate to be processed is rotated at a constant speed. The supplied first amount of the coating agent functions as a surfactant for improving the affinity between the surface of the substrate to be processed and the coating agent, and the second amount of the coating agent supplied from the second time on is the same. Since the coating material is adapted to the surface and becomes slippery, the coating agent is uniformly diffused over the entire surface of the substrate to be processed, and a coating film having a uniform thickness can be obtained.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effect of the coating method, the second amount is set to be larger than the first amount, so that the spread of the coating liquid is improved, and the film thickness of the coating film can be controlled with higher accuracy. it can.

According to the third aspect of the present invention, the first
And the second amount is 0.1 to 0.1 cc.
Since it is 3 to 0.39 cc, the spread of the coating liquid becomes good, and the thickness of the coating film can be controlled with higher precision.

According to the fourth aspect of the present invention, a first aspect is provided.
In addition to the effect of the coating method, the substrate to be processed is accelerated to the second speed at the first acceleration after the supply of the coating agent, and a strong centrifugal force is generated to diffuse the coating agent. The coating film can be made thin.

According to the fifth aspect of the present invention, a first aspect is provided.
In addition to the effect of the coating method, the substrate to be processed is accelerated to the second speed at the first acceleration after the supply of the coating agent to be supplied first is completed, and the second coating agent is generated while generating a strong centrifugal force. Since the coating agent is supplied to diffuse the coating agent, the coating film can be more reliably thinned.

According to the sixth aspect of the present invention, a fourth aspect is provided.
Or, in addition to the effect of the coating method of 5, since the second amount is set to be larger than the first amount, the spread of the coating liquid becomes good, and the film thickness of the coating film is controlled with higher precision. be able to.

According to the seventh aspect of the present invention, the first
And the second amount is 0.1 to 0.1 cc.
Since it is 3 to 0.39 cc, the spread of the coating liquid becomes good, and the thickness of the coating film can be controlled with higher precision.

According to the present invention as set forth in claim 8, claim 1 is as follows.
In addition to the effects of the coating method, the thickness of the coating film on the substrate to be processed is detected, and the time for rotating at the second speed is controlled based on the detected film thickness. The thickness of the film can be controlled.

According to the ninth aspect of the present invention, a first aspect is provided.
In addition to the effects of the coating method, the film thickness of the coating film on the substrate to be processed is detected, and the time for accelerating at the second acceleration is controlled based on the detected film thickness. Can be controlled.

According to the tenth aspect of the present invention, a second amount of coating agent is supplied onto the substrate while accelerating the substrate to be processed at a first acceleration to a second speed.
Since the thickness of the coating film on the substrate to be processed is detected and the time for rotating at the second speed is controlled based on the detected thickness, the thickness of the coating film is managed with higher accuracy. Can be.

According to the eleventh aspect of the present invention, in addition to the effect of the coating method of the twelfth aspect, the thickness of the coating film on the substrate to be processed is detected, and the thickness of the coating film is determined based on the detected thickness. 2
Since the acceleration time is controlled by the acceleration, the film thickness of the coating film can be managed with higher accuracy.

According to the twelfth aspect of the present invention, in addition to the effects of the coating method of the first aspect, the thickness of the coating film on the substrate to be processed is detected, and the thickness of the coating film is determined based on the detected thickness. Since the second acceleration, which further accelerates from the speed of 2, is controlled, the thickness of the coating film can be managed with higher accuracy.

According to the thirteenth aspect of the present invention, in addition to the effect of the coating method of the fourteenth aspect, a second acceleration is applied to the processing target substrate at a first acceleration to a second speed. Since the amount of the coating agent is supplied, the coating film can be more reliably thinned.

[Brief description of the drawings]

FIG. 1 is a plan view of a coating and developing system including a resist coating unit according to an embodiment of the present invention.

FIG. 2 is a front view of a coating and developing system including a resist coating unit according to an embodiment of the present invention.

FIG. 3 is a rear view of the coating and developing system including the resist coating unit according to the embodiment of the present invention.

FIG. 4 is a sectional view of a resist coating unit according to the embodiment of the present invention.

FIG. 5 is a plan view of a resist coating unit according to the embodiment of the present invention.

FIG. 6 is a block diagram showing a control system of the resist coating unit according to the embodiment of the present invention.

FIG. 7 is a flowchart showing steps of a resist coating method according to an embodiment of the present invention.

FIG. 8 is a timing chart showing steps of a resist coating method according to an embodiment of the present invention.

FIG. 9 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 10 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 11 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 12 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 13 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 14 is a view schematically showing one step of a resist coating method according to an embodiment of the present invention.

FIG. 15 is a view schematically showing one step of a resist coating method according to the embodiment of the present invention.

FIG. 16 is a view schematically showing one step of a resist coating method according to the embodiment of the present invention.

FIG. 17 is a graph showing a film thickness distribution of a coating film formed by applying the resist coating method according to the present embodiment.

FIG. 18 is a graph showing a film thickness distribution of a coating film formed by applying the resist coating method according to the present embodiment.

FIG. 19 is a graph showing a film thickness distribution of a coating film formed by applying the resist coating method according to the present embodiment.

FIG. 20 is a flowchart showing steps of a resist coating method according to a second embodiment of the present invention.

FIG. 21 is a timing chart showing steps of a resist coating method according to a second embodiment of the present invention.

FIG. 22 is a block diagram showing a control system of a resist coating unit according to a third embodiment of the present invention.

FIG. 23 is a flowchart showing steps of a resist coating method according to a third embodiment of the present invention.

[Explanation of symbols]

 W wafer 51 spin chuck 52 motor S sensor 100 control unit

Claims (13)

[Claims] A first substrate on a substrate rotating at a constant speed;
And a step of supplying a second amount of the coating material onto the substrate to be processed rotating at the speed. 2. The coating method according to claim 1, wherein the second amount is larger than the first amount. 3. The coating method according to claim 1, wherein the first amount is 0.01 to 0.1 cc, and the second amount is 0.3 to 0.39 cc. A coating method characterized by the above-mentioned. 4. A step of supplying a first amount of the coating material on the substrate to be rotated at a first speed, and a second amount of the coating material on the substrate to be rotated at the first speed. And a step of accelerating the substrate to be processed to a second speed at a first acceleration. 5. A step of supplying a first amount of a coating material onto a substrate to be processed which rotates at a first speed, and said substrate being processed while accelerating said substrate at a first acceleration to a second speed. Supplying a second amount of coating agent onto the substrate. 6. The coating method according to claim 4, wherein the second amount is larger than the first amount. 7. The coating method according to claim 6, wherein the first amount is 0.01 to 0.1 cc, and the second amount is 0.3 to 0.39 cc. Characteristic coating method. 8. A step of supplying a first amount of coating agent onto the substrate to be processed rotating at a first speed, and a step of applying a second amount onto the substrate to be processed rotating at said first speed. A step of supplying an agent; a step of accelerating the substrate to be processed to a second speed at a first acceleration; a step of detecting a film thickness of a coating film on the substrate to be processed; Controlling the time of rotation at the second speed. 9. A method for supplying a first amount of coating material onto a substrate to be processed rotating at a first speed, and a method for supplying a second amount of coating material onto a substrate to be rotated at said first speed. Supplying the substrate; accelerating the substrate to be processed at a first acceleration to a second speed; detecting a film thickness of a coating film on the substrate to be processed; , From the second speed to a second
Controlling the time of acceleration by acceleration. 10. A step of supplying a first amount of a coating material onto a substrate to be processed rotating at a first speed, wherein the substrate to be processed is accelerated to a second speed at a first acceleration to a second speed. Supplying a second amount of coating agent onto the substrate; detecting a film thickness of the coating film on the substrate to be processed; rotating at the second speed based on the detected film thickness Controlling the time. 11. A step of supplying a first amount of a coating material onto a substrate to be processed rotating at a first speed, wherein the substrate is processed while accelerating the substrate to a second speed at a first acceleration. A step of supplying a second amount of coating agent on the substrate; a step of detecting a film thickness of the coating film on the substrate to be processed; and a second speed from the second speed based on the detected film thickness.
Controlling the time of acceleration by acceleration. 12. A step of supplying a first amount of the coating material onto the substrate to be rotated at a first speed, and a step of supplying a second amount of the coating material onto the substrate to be rotated at the first speed. Supplying the substrate; accelerating the substrate to be processed at a first acceleration to a second speed; detecting a film thickness of a coating film on the substrate to be processed; And controlling a second acceleration that further accelerates from the second speed. 13. A process for supplying a first amount of a coating material onto a substrate to be processed rotating at a first speed, wherein the substrate is processed while accelerating the substrate at a first acceleration to a second speed. Supplying a second amount of coating agent onto the substrate; detecting a film thickness of the coating film on the non-processed substrate; further accelerating the second speed based on the detected film thickness. Controlling the second acceleration to be performed.