JP2010207788A - Resist applying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist applying method capable of efficiently applying resist liquid on the entire wafer surface with a smaller supply amount, and decreasing the consumption of the resist liquid. <P>SOLUTION: The resist applying method includes: a solvent supply process S0 of supplying a solvent on the rough center of a wafer which is made to almost stand still; a first process S1 of rotating the wafer at a first rotating speed V1 while supplying the resist liquid onto the solvent on the rough center of the wafer after the solvent supply process S0; a second process S2 of rotating the wafer at a second rotating speed V2 lower than the first rotating speed V1 after the first process S1; and a third process S3 of rotating the wafer at a third rotating speed V3 lower than the first rotating speed V1 and higher than the second rotating speed V2 after the second process S2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resist coating method for coating a resist on a substrate such as a semiconductor wafer.

  In a photolithography process in a semiconductor device manufacturing process, for example, a resist coating process for applying a resist solution on a semiconductor wafer (hereinafter referred to as “wafer”) to form a resist film, an exposure process for exposing the resist film to a predetermined pattern, A development process for developing the exposed resist film is sequentially performed, and a predetermined resist pattern is formed on the wafer. In this resist coating process, a resist solution is applied to the surface of the wafer by supplying the resist solution from the nozzle to the approximate center on the surface of the rotating wafer and diffusing the resist on the wafer by centrifugal force. The law is used.

  In this spin coating method, for example, in a state where the wafer is fixed and held by vacuum chucking by a spin chuck, the wafer is rotated together with the spin chuck by a rotation driving means, and a resist nozzle is arranged at the rotation center of the wafer surface from a resist nozzle disposed above the wafer. Add the solution dropwise. The dropped resist solution spreads (diffuses) toward the outer periphery in the radial direction of the wafer by centrifugal force, and then the dropping of the resist solution stops, but the rotation of the resist solution spread on the wafer surface continues. Drying is performed (for example, refer to Patent Document 1).

JP 2001-307984 A

  However, when applying a resist by supplying a small amount of resist solution onto a substrate such as a semiconductor wafer using the above resist coating method, there are the following problems.

  When the resist solution is applied onto the substrate, a so-called pre-wet treatment is performed in which the entire surface of the wafer surface is wetted with a solvent such as thinner before applying the resist solution. By performing the pre-wet process, the resist is more easily diffused on the surface of the wafer that has been subjected to the pre-wet process, and as a result, a uniform resist film can be formed with a smaller amount of the resist solution supplied. This is because the consumption of the resist solution can be further reduced.

  On the other hand, since miniaturization and thinning of semiconductor device patterns are required, various resist solutions that can be applied to such photolithography have been developed. However, it is required that the resist solution has various physical properties. For this reason, the cost of the resist solution is increasing as compared with the conventional case, and at present, the resist solution is extremely expensive. For this reason, the consumption of the resist solution must be further reduced. Therefore, the consumption of the resist solution must be reduced also by performing the pre-wet process.

  However, when the resist is applied after the pre-wet treatment is performed on the substrate, there is a problem that the solvent film is not vaporized particularly in the peripheral portion of the substrate before the resist solution spreads. When the solvent film is not vaporized, it is difficult to diffuse the resist solution on the surface of the substrate, and there is a problem that a large amount of resist solution must be supplied to apply the resist solution to the entire surface. there were.

  The present invention has been made in view of the above points, and provides a resist coating method that can efficiently apply a resist solution to the entire wafer surface with a smaller supply amount, and can reduce consumption of the resist solution. It is to provide.

  In order to solve the above-described problems, the present invention is characterized by the following measures.

  According to a first aspect of the present invention, there is provided a resist coating method comprising: a solvent supplying step for supplying a solvent on a substantially center of a substantially stationary substrate; and a substantially center of the substrate after the solvent supplying step. A first step of rotating the substrate at a first rotational speed while supplying a resist solution to the substrate, and a second rotational speed lower than the first rotational speed after the first step. And a third step of rotating the substrate at a third rotational speed lower than the first rotational speed and higher than the second rotational speed after the second process. And have.

  According to a second invention, in the resist coating method according to the first invention, the solvent is a solvent for pre-wetting the substrate. In the first step, the solvent is removed from the center side of the substrate. The substrate is pre-wet treated by diffusing to the outer peripheral side.

  According to a third invention, in the resist coating method according to the first or second invention, the viscosity of the solvent is smaller than the viscosity of the resist.

  According to a fourth invention, in the resist coating method according to any one of the first to third inventions, in the first step, the supplied resist solution is diffused from the center side to the outer peripheral side of the substrate, In the second step, the shape of the diffused resist solution is adjusted, and in the third step, the resist solution on the substrate is shaken off and dried.

  According to the present invention, the resist solution can be efficiently applied to the entire surface of the wafer with a smaller supply amount, and the consumption of the resist solution in the resist coating process can be reduced.

1 is a plan view showing the overall configuration of a coating and developing system including a resist coating apparatus used for performing a resist coating method according to an embodiment of the present invention. 1 is a front view showing an overall configuration of a coating and developing system including a resist coating device used for performing a resist coating method according to an embodiment of the present invention. It is a rear view which shows the whole structure of the coating and developing system provided with the resist coating apparatus used in order to perform the resist coating method which concerns on embodiment of this invention. It is sectional drawing which shows the resist coating apparatus unit COT for performing the resist coating method which concerns on embodiment of this invention. It is a top view which shows the resist coating apparatus unit COT for performing the resist coating method which concerns on embodiment of this invention. It is a figure which shows the structure of the control system of the resist coating unit COT for performing the resist coating method which concerns on embodiment of this invention. It is a graph which shows the state of rotation control of the resist coating apparatus unit in the resist coating method which concerns on embodiment of this invention with the state of rotation control of the resist coating apparatus unit in the conventional resist coating method. It is a top view which shows the state of the resist liquid on a wafer at the time of performing the resist coating method which concerns on embodiment of this invention. It is a top view which shows the state of the resist liquid on a wafer at the time of performing the conventional resist coating method. It is sectional drawing which shows typically the state of the resist liquid on a wafer at the time of performing the resist coating method which concerns on embodiment of this invention. It is sectional drawing which shows typically the state of the resist liquid on a wafer at the time of performing the conventional resist coating method.

Next, a mode for carrying out the present invention will be described with reference to the drawings.
(Embodiment)
FIG. 1 to FIG. 3 are diagrams showing the overall configuration of a coating and developing system including a resist coating apparatus used for performing the resist coating method according to the present embodiment. FIG. 1 is a plan view, and FIG. The front view and FIG. 3 are the rear views.

  As shown in FIG. 1, the coating and developing treatment system 1 carries a plurality of wafers W as a substrate in a wafer cassette CR, for example, 25 wafers from the outside to the system, or removes them from the system. On the other hand, a cassette station 10 for loading and unloading the wafer W, and various single-wafer processing units for performing predetermined processing on the wafer W one by one in the coating and developing process are arranged in multiple stages at predetermined positions. And an interface unit 12 for transferring the wafer W between an exposure apparatus (not shown) provided adjacent to the processing station 11 is integrally connected.

  In the cassette station 10, as shown in FIG. 1, a plurality of, for example, up to four wafer cassettes CR are placed at positions of the positioning projections 20a on the cassette mounting table 20 with their respective wafer entrances facing the processing station 11 side. A wafer carrier 21 that is placed in a line in the direction and is movable in the cassette arrangement direction (X direction) and the wafer arrangement direction (Z direction: vertical direction) accommodated in the wafer cassette CR is selected for each wafer cassette CR. Access.

  Further, the wafer carrier 21 is configured to be rotatable in the θ direction so that it can also access the alignment unit ALIM belonging to the multi-stage unit portion of the third processing unit group G3 on the processing station 11 side as will be described later. It has become.

  As shown in FIG. 1, the processing station 11 is provided with a vertical transfer type main wafer transfer mechanism 22 equipped with a wafer transfer device, and all the processing units are arranged in multiple stages around one set or a plurality of sets. Has been.

  As shown in FIG. 3, the main wafer transfer mechanism 22 is equipped with a wafer transfer device 46 that can move up and down in the vertical direction (Z direction) inside a cylindrical support 49. 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 around the rotation shaft by the rotational driving force of the motor, whereby the wafer transfer device 46 is rotated. Is freely rotatable in the θ direction. In addition, you may comprise the cylindrical support body 49 so that it may connect with another rotating shaft (not shown) rotated by a motor.

  The wafer transfer device 46 includes a plurality of holding members 48 that can move in the front-rear direction of the transfer base 47, and the transfer of the wafers W between the processing units is realized by these holding members 48.

  Further, as shown in FIG. 1, in this example, five processing unit groups G1, G2, G3, G4, and G5 can be arranged, and the multistage unit of the first and second processing unit groups G1 and G2 is arranged. Is arranged on the front side of the system (front side in FIG. 1), the multi-stage unit of the third processing unit G3 is arranged adjacent to the cassette station 10, and the multi-stage unit of the fourth processing unit group G4 is the interface unit 12. The multi-stage units of the fifth processing unit group G5 can be arranged on the back side.

  As shown in FIG. 2, in the first processing unit group G1, two spinner type processing units, for example, a resist coating unit COT and a developing unit, that perform predetermined processing by placing the wafer W on a spin chuck in a cup CP. DEV is stacked in two stages from the bottom. Also in the second processing unit group G2, two spinner processing units, for example, a resist coating unit COT and a developing unit DEV are stacked in two stages in order from the bottom. These resist coating apparatus units COT are preferably arranged at the lower stage in this manner because the draining of the resist solution is troublesome both mechanically and in terms of maintenance. However, it is of course possible to arrange them in the upper stage as needed.

  As shown in FIG. 3, in the third processing unit group G3, an open type processing unit that performs predetermined processing by placing the wafer W on the mounting table SP, for example, a cooling unit COL that performs cooling processing, and resist fixability. Adhesion unit AD for performing so-called hydrophobic treatment for enhancing, alignment unit ALIM for performing alignment, extension unit EXT, pre-baking unit PREBAKE for performing heat treatment before exposure processing, and post-baking for performing heat treatment after exposure processing The units POBAKE are stacked in, for example, eight levels in order from the bottom.

  Also in the fourth processing unit group G4, open type processing units, for example, a cooling unit COL, an extension / cooling unit EXTCOL, an extension unit EXT, a cooling unit COL, a pre-baking unit PREBAKE, and a post-baking unit POBAKE are arranged in order from the bottom, for example, 8 It is stacked on the stage.

  In this way, the cooling unit COL and the extension / cooling unit EXTCOL having a low processing temperature are arranged in the lower stage, and the baking unit PREBAKE, the post-baking unit POBAKE and the adhesion unit AD having a high processing temperature are arranged in the upper stage. It is possible to reduce the thermal mutual interference. Of course, a random multistage arrangement may be used.

  As shown in FIG. 1, the interface unit 12 has the same dimensions as the processing station 11 in the depth direction (X direction), but is set to a smaller size in the width direction. A portable pickup cassette CR and a stationary buffer cassette BR are arranged in two stages on the front part of the interface unit 12, while a peripheral exposure device 23 is arranged on the back part, and a central part. Is provided with a wafer carrier 24. The wafer carrier 24 is moved in the X direction and the Z direction to access both cassettes CR and BR and the peripheral exposure apparatus 23. The wafer transfer body 24 is configured to be rotatable in the θ direction, and the extension unit EXT belonging to the multi-stage unit of the fourth processing unit group G4 on the processing station 11 side, and further on the adjacent exposure apparatus side. The wafer transfer table (not shown) can also be accessed.

  In the coating and developing processing system 1, as shown in FIG. 1, a multi-stage unit of the fifth processing unit group G5 indicated by a broken line can be arranged on the back side of the main wafer transfer mechanism 22. The multi-stage unit of the fifth processing unit group G5 is configured to be able to shift sideways along the guide rail 25 as viewed from the main wafer transfer mechanism 22. Therefore, even when the multi-stage unit of the fifth processing unit group G5 is provided as shown in the drawing, a space is secured by sliding along the guide rail 25, so that the main wafer transfer mechanism 22 is behind. Therefore, maintenance work can be easily performed.

  Next, a resist coating apparatus unit COT for performing the resist coating method according to the present embodiment will be described. 4 and 5 are a sectional view and a plan view showing the resist coating unit COT.

  An annular cup CP is arranged at the center of the resist coating unit COT, and a spin chuck 52 is arranged inside the cup CP. The spin chuck 52 is rotationally driven by a drive motor 54 with the wafer W fixed and held by vacuum suction. The drive motor 54 is disposed in an opening 50a provided in the unit bottom plate 50 so as to be movable up and down. Are combined. A cylindrical cooling jacket 64 made of, for example, SUS is attached to the side surface of the drive motor 54, and the flange member 58 is attached so as to cover the upper half of the cooling jacket 64.

  At the time of resist application, the lower end 58a of the flange member 58 is in close contact with the unit bottom plate 50 in the vicinity of the outer periphery of the opening 50a, thereby sealing the inside of the unit. When the wafer W is transferred between the spin chuck 52 and the holding member 48 of the main wafer transfer mechanism 22, the elevating drive means 60 lifts the drive motor 54 or the spin chuck 52 upward to lower the lower end of the flange member 58. From the unit bottom plate 50.

  A resist nozzle 86 for supplying a resist solution to the surface of the wafer W is connected to a resist supply unit (described later) via a resist supply pipe 88. The registration nozzle 86 is detachably attached to the tip of the registration nozzle scan arm 92 via the nozzle holder 100. The registration nozzle scan arm 92 is attached to an upper end portion of a vertical support member 96 that is horizontally movable on a guide rail 94 laid in one direction (Y direction) on the unit bottom plate 50, and is not shown in the Y direction. The drive mechanism moves in the Y direction integrally with the vertical support member 96.

  The resist nozzle scan arm 92 is also movable in the X direction perpendicular to the Y direction in order to selectively attach the resist nozzle 86 in the resist nozzle standby section 90, and is also moved in the X direction by an X direction driving mechanism (not shown). It is supposed to be.

  Furthermore, the resist nozzle standby portion 90 inserts the discharge port of the resist nozzle 86 into the solvent atmosphere chamber port 90a and is exposed to the solvent atmosphere therein, so that the resist solution at the nozzle tip is not solidified or deteriorated. Yes. Also, a plurality of resist nozzles 86 are provided, and these nozzles can be used properly according to the type of resist solution, for example.

  In addition, a solvent nozzle 101 for supplying a solvent, for example, thinner, to wet the wafer surface to the wafer surface prior to the supply of the resist solution to the wafer surface is attached to the tip portion (nozzle holder 100) of the resist nozzle scan arm 92. It has been. The solvent nozzle 101 is connected to a solvent supply section described later via a solvent supply pipe (not shown). The solvent nozzle 101 and the resist nozzle 86 are attached so that each discharge port is positioned on a straight line along the Y movement direction of the resist nozzle scan arm 92.

  Further, on the guide rail 94, not only a vertical support member 96 that supports the resist nozzle scan arm 92 but also a vertical support member 122 that supports the rinse nozzle scan arm 120 and is movable in the Y direction is provided. The rinse nozzle scan arm 120 and the rinse nozzle 124 are set to the side of the cup CP by the Y-direction drive mechanism (not shown), and the wafer W installed on the spin chuck 52 is positioned on the spin chuck 52. Translation or linear motion is performed between the rinse liquid discharge position (position of the dotted line) set right above the peripheral portion.

  FIG. 6 is a diagram showing the configuration of the control system of the resist coating unit COT.

  The control unit 130 controls each unit in the resist coating apparatus unit COT, and controls the resist supply unit 131, the solvent supply unit 132, and the like in addition to controlling the drive of the drive motor 54, for example. Specifically, the control unit 130 controls the rotational speed of the drive motor 54 in several stages, for example, in three stages during resist coating as will be described later. The control unit 130 also controls the supply of the resist solution from the resist supply unit 131 to the resist nozzle 86 and the supply of a solvent, for example, thinner, from the solvent supply unit 132 to the solvent nozzle 101.

  Next, the resist coating operation in the resist coating unit COT when performing the resist coating method according to the present embodiment will be described with reference to FIGS. FIG. 7 is a graph showing the state of rotation control of the resist coating apparatus unit in the resist coating method according to the present embodiment, together with the state of rotation control of the resist coating apparatus unit in the conventional resist coating method. FIG. 7A is a graph showing the state of rotation control in the resist coating method according to the present embodiment, and FIG. 7B is a graph showing the state of rotation control in the conventional resist coating method. FIG. 8 is a plan view showing the state of the resist solution on the wafer when performing the resist coating method according to the present embodiment. Note that the length of time of each step in FIG. 7 does not necessarily correspond to the actual length of time because priority is given to the ease of understanding the technology. Similarly, the rotational speed in FIG. 7 does not necessarily correspond to the actual rotational speed in order to prioritize the ease of understanding of the technology.

  As shown in FIG. 4, when the wafer W is transported to the position just above the cup CP of the resist coating unit COT by the holding member 48 of the main wafer transport mechanism 22, the wafer W is moved up and down by an air cylinder, for example. The vacuum chucking is performed by the spin chuck 52 that has been lifted by 60 and the lifting guide means 62. After the wafer W is vacuum-sucked by the spin chuck 52, the main wafer transfer mechanism 22 pulls the holding member 48 back from the resist coating apparatus unit COT, and completes the delivery of the wafer W to the resist coating apparatus unit COT.

  Next, the spin chuck 52 is lowered so that the wafer W is in a fixed position in the cup CP, and the drive motor 54 starts to rotate the spin chuck 52.

  Next, the movement of the nozzle holder 100 from the resist nozzle standby unit 90 is started. The nozzle holder 100 is moved along the Y direction.

  When the discharge port of the solvent nozzle 101 reaches the center of the spin chuck 52 (the center of the wafer W), a solvent, for example, a thinner is supplied to the surface of the rotating wafer W. The solvent supplied to the wafer surface spreads uniformly from the center of the wafer to its entire periphery by centrifugal force.

  Next, the nozzle holder 100 is moved in the Y direction until the discharge port of the resist nozzle 86 reaches the center of the spin chuck 52 (the center of the wafer W), and the resist solution PR is discharged from the discharge port of the resist nozzle 86. The liquid is dropped on the center of the surface of the rotating wafer W, and the resist is applied to the surface of the wafer W.

  In the present embodiment, the controller 130 controls the number of rotations of the wafer W (that is, the number of rotations of the drive motor 54) and the discharge of the solvent or resist solution from the nozzles, and S0 to S3 shown in FIG. The process of is implemented. Note that the steps S1 to S3 shown in FIG. 7A correspond to the first to third steps in the present invention. 8A to 8C show states of the resist solution PR on the wafer W at the time points A, B, and C shown in FIG. 7A.

  First, the solvent supply process shown in S0 of FIG. The solvent supply step is a step of supplying a solvent on the substantially center of the substantially stationary substrate. Specifically, at a point A in FIG. 7A, the wafer W is not rotated, or the solvent P101, which is a solvent, is placed in the approximate center of the wafer W from the solvent nozzle 101 in a state where the rotation speed is 0 to 50 rpm. Supply. FIG. 8A is a plan view showing the state of the wafer W at the point A in FIG.

  As shown in FIG. 8A, in the solvent supply step S0, the thinner PW that is a solvent has a substantially stationary substrate, so that the centrifugal force does not work or the working centrifugal force is weak, and the wafer W is substantially at the center. Stay on. Further, the supply amount of the thinner PW which is a solvent supplied in the solvent supply step S0 is substantially the same as or slightly faster than the resist solution PR is diffused to the outer peripheral side in the radial direction of the wafer W later in the first step. A supply amount sufficient to allow a certain thinner PW to diffuse to the outer peripheral side in the radial direction of the wafer W and to be diffused to the entire surface of the wafer W is sufficient, for example, 0.5 ml.

  Next, the first step shown in S1 of FIG. In the first step S1, after the solvent supply step S0, the substrate (wafer W) is supplied at the first rotational speed V1 while supplying the resist solution PR on the solvent PW substantially at the center of the substrate (wafer W). ), The solvent is diffused from the center side of the substrate to the outer peripheral side to pre-wet the substrate (wafer W), and the supplied resist solution is diffused from the center side of the substrate (wafer W) to the outer peripheral side. It is. Specifically, as shown in S1 of FIG. 7A, the wafer W is accelerated to a rotational speed (first rotational speed V1) of 2000 to 4000 rpm, more preferably 2500 rpm, for example, for 2 seconds. Then, the resist solution PR is supplied from the resist nozzle 86 onto substantially the center of the wafer W, and is applied while being diffused to the outer peripheral side in the radial direction of the wafer W. FIG. 8B shows the supply of the resist solution PR onto the wafer W while rotating the wafer W at the first rotation speed V1 at the point B in FIG. 7A, that is, in the first step S1. It is a top view which shows the state of the wafer W immediately after starting.

  As shown in FIG. 8B, the resist solution PR is supplied on the thinner PW, which is a solvent, substantially on the center of the substrate (wafer W). Thereafter, when the substrate (wafer W) rotates at the first rotation speed V1, centrifugal force acts on the thinner PW and the resist solution PR, which are solvents, and the thinner PW and the resist solution PR, which are solvents, are transferred to the substrate ( The wafer W) is diffused from the radial center to the outer periphery.

  Here, since the outer periphery of the resist solution PR diffused to the outer peripheral side in the radial direction of the wafer W is formed with a film of thinner PW that is a solvent in the peripheral portion of the wafer W, as will be described later, It reaches the outer periphery. That is, the supply amount supplied for diffusing the resist solution PR over the entire surface of the wafer W in the first step S1 is about half of the supply amount when performing the conventional prewetting process. Specifically, in the first step S1, the supply amount of the resist solution supplied to the center side of the surface of the wafer W is, for example, 0.5 ml, which is half of the conventional supply amount of 1.0 ml. .

  Next, the second step shown in S2 of FIG. In the second step S2, after the first step S1, the substrate (wafer W) is rotated at a second rotational speed V2 lower than the first rotational speed V1, and the shape of the diffused resist solution PR is adjusted. It is. Specifically, as shown in S2 of FIG. 7A, the wafer W is decelerated and rotated to a rotational speed (second rotational speed V2) of 50 to 2000 rpm, more preferably 100 rpm. As time for performing 2nd process S2, about 1 second is preferable, for example. FIG. 8C is a plan view showing the state of the wafer W after the second step S2 is performed.

  As shown in FIG. 8C, the outer periphery of the resist solution PR that has reached the outer periphery of the wafer W in the first step S1 is substantially the same position in the second step S2 as in the first step S1. It is in. In addition, at the outer periphery of the diffused resist solution PR, the resist solution PR accumulates on the outer periphery and the thickness increases, so that the shape of the resist solution PR is adjusted.

  Next, the third step S3 is performed. In the third step S3, after the second step S2, the substrate (wafer W) is rotated at a third rotational speed V3 that is lower than the first rotational speed V1 and higher than the second rotational speed V2. In this step, the upper resist solution PR is shaken off and dried. Specifically, as shown in FIG. 7A, the wafer W is accelerated to 1000 to 2000 rpm, more preferably 1500 rpm (third rotation speed V3), and the resist is rotated for 30 seconds, for example. The liquid PR is shaken off and dried.

  As described above, by rotating the wafer W at the first rotation speed V1, which is a relatively high rotation speed, in the first step S1, that is, when supplying the resist solution PR, the wafer is coupled with the pre-wet processing. The resist solution PR can be spread or diffused macroscopically and uniformly on the surface of W.

  Further, during the subsequent swing-off drying of the resist solution PR in the third step S3, in the second step S2, that is, the wafer W is rotated at the second rotation speed V2 that is lower than the first rotation speed V1. Therefore, the resist solution PR can be uniformly spread or diffused microscopically over the entire surface of the wafer W, and the resist solution can be efficiently applied to the entire wafer surface with a smaller supply amount. The consumption amount of the resist solution in the resist coating process can be reduced.

  Next, in the resist coating method according to the present embodiment, when the resist solution PR is shaken and dried in the third step S3, the resist solution PR is uniformly spread or diffused microscopically on the surface of the wafer W. Regarding the effects that can be achieved, and in the first step S1, the resist solution can be efficiently applied to the entire surface of the wafer with a smaller supply amount, and the consumption of the resist solution in the resist coating process can be reduced. ,explain.

  First, in the resist coating method according to the present embodiment, the effect of being able to diffuse the resist solution PR evenly on the surface of the wafer W even when the resist solution is shaken and dried in the third step S3. Will be described.

  For example, consider a case where uneven grooves are formed on the surface of the wafer W, such as a wafer W on which a base film such as a circuit pattern is formed. In this case, when the wafer W is rotated at the same rotational speed as the resist application (first rotational speed V1) or higher than the first rotational speed V1 at the time of spin-drying as in the prior art, for example, the wafer W The resist solution that diffuses on the surface to the outer peripheral side in the radial direction of the wafer W due to centrifugal force does not sufficiently enter the concave and convex grooves, and the thickness of the resist formed in the concave and convex grooves is the same as that of the resist formed at other positions. It becomes thinner than the film thickness.

  On the other hand, in the resist coating method according to the present embodiment, the wafer W is rotated at a rotational speed (second rotational speed V2) lower than the rotational speed (first rotational speed V1) at the time of resist coating during swing-off drying. Therefore, the resist solution PR that diffuses the surface of the wafer W toward the outer peripheral side in the radial direction of the wafer W uniformly enters the concave and convex grooves, and the resist solution PR can be uniformly diffused on the surface of the wafer W.

  Therefore, according to the resist coating method according to the present embodiment, the resist film can be uniformly formed on the surface of the uneven wafer W both macroscopically and microscopically.

  Next, in the resist coating method according to the present embodiment, in the first step S1, the resist solution PR can be efficiently applied to the entire surface of the wafer W with a smaller supply amount, and the consumption amount of the resist solution PR can be reduced. With reference to FIGS. 7 to 11, the resist coating method according to the present embodiment shown in FIGS. 7A, 8, and 10 will be described with reference to FIGS. This will be described in comparison with the conventional resist coating method shown in FIG. FIG. 9 is a plan view showing the state of the resist solution on the wafer when performing the conventional resist coating method. FIG. 10 is a cross-sectional view schematically showing the state of the resist solution on the wafer when performing the resist coating method according to the present embodiment. FIG. 11 is a cross-sectional view schematically showing the state of the resist solution on the wafer when performing the conventional resist coating method. FIGS. 9A to 9D show the state of the resist solution on the wafer at time points A1 ′, A2 ′, B ′, and C ′ in FIG. 7B. FIGS. 10A to 10C show the state of the resist solution on the wafer at points A, B, and C in FIG. FIGS. 11A to 11D show the state of the resist solution on the wafer at time points A1 ′, A2 ′, B ′, and C ′ in FIG. 7B.

  First, the state of the thinner PW which is a solvent at the time point A in the solvent supply step S0 will be described. FIG. 10A shows the state of the thinner PW that is the solvent on the wafer W at the time point A. FIG. At the point A, the thinner PW, which is a solvent, remains at the approximate center of the wafer W because the centrifugal force does not work or the working centrifugal force is weak because the wafer W is substantially stationary.

  Next, the states of the thinner PW and the resist solution PR that are solvents at the time point B in the first step S1 will be described. FIG. 10B shows the state of the resist solution PR on the wafer W at time B. At the time point B, the wafer W is immediately after the rotation speed reaches the first rotation speed V1, and centrifugal force starts to act on the thinner PW, which is a solvent on the center of the wafer W surface, and is a solvent. The thinner PW begins to diffuse from the radial center of the surface of the wafer W to the outer peripheral side. Further, the resist solution PR supplied on the thinner PW as a solvent on the center of the surface of the wafer W does not have a sufficient centrifugal force, and the resist solution PR accumulates on the center of the surface of the wafer W. Yes.

  Thereafter, by performing the first step S1, sufficient centrifugal force acts on the thinner PW and the resist solution PR, which are solvents on the center of the surface of the wafer W, so that the thinner PW and the resist solution PR, which are solvents, become the diameter of the wafer W. It is diffused from the direction center side to the outer periphery side. FIG. 10C shows the state of the resist solution PR on the wafer W at time C in the second step S2. In the second step S2, the speed is reduced to the second rotational speed V2, which is lower than the first rotational speed V1, and the wafer W is rotated at the second rotational speed V2. The centrifugal force acting on the resist solution PR is smaller than the centrifugal force in the first step S1. Therefore, the resist solution PR is in a state where the diffusion to the radially outer peripheral side of the wafer W has stopped on the lower side in contact with the wafer W.

  The thinner PW that is a solvent has higher wettability with respect to the substrate (wafer W) than the resist solution PR. Accordingly, in the first step S1, the thinner PW that is a solvent diffuses to the outer peripheral side in the radial direction of the wafer W before the resist solution PR. That is, the surface of the substrate (wafer W) may be wetted by the thinner PW that is a solvent before the resist solution PR diffuses to the outer peripheral side in the radial direction of the wafer W over substantially the entire surface of the substrate (wafer W). it can. Accordingly, in the present embodiment, the resist solution PR is diffused while performing the pre-wetting process by supplying the resist solution PR onto the thinner PW that is the solvent at the approximate center of the substrate (wafer W). Can do.

  Thus, since the pre-wet process can be performed by performing the first step S1 without performing the pre-wet process step independently, compared to the conventional case where the pre-wet process step is performed independently in advance. Vaporization of the thinner PW, which is a solvent, is suppressed, and the resist solution PR is more easily diffused to the periphery of the wafer W, and a uniform resist film is formed with a smaller amount of the resist solution PR supplied than in the conventional case. And consumption of the resist solution PR can be reduced.

  Further, in the present embodiment, by using the solvent PW having a viscosity lower than that of the resist solution PR, it is possible to enhance the effect that the solvent PW is diffused to the outer peripheral side in the radial direction of the wafer W before the resist solution PR.

  On the other hand, in the conventional resist coating method, as shown in FIG. 7B, a pre-wet treatment step S02 is provided between the solvent supply step S01 and the first step S1. The pre-wet treatment step is a step of performing a so-called pre-wet treatment in which the entire surface of the wafer W is wetted with a solvent such as thinner prior to application of the resist solution PR. After performing the solvent supply step S01 shown in FIGS. 7B, 9A, and 11A, as shown in FIGS. 7B, 9B, and 11B, The wafer W is accelerated to a rotational speed of 0 to 2000 rpm, more preferably 1000 rpm (pre-wet rotational speed V0), and the solvent P is a thinner PW which is a solvent in the approximate center of the wafer W from the solvent nozzle 101 for 0.1 seconds, for example. Is diffused to the outer peripheral side in the radial direction of the wafer W so that the surface of the wafer W is wetted with the solvent. By performing the pre-wet process, the resist solution PR is more easily diffused.

  When the resist solution PR is applied by performing the first step S1 after performing the pre-wet treatment step S02, as shown in FIGS. 7B, 9B, and 11B, the pre-wet process is performed. In the processing step S02, the solvent PW, which is a solvent, is diffused over the entire surface of the wafer W, and as shown in FIGS. 7B, 9C, and 11C, a solvent is applied on the surface of the wafer W. After forming a film of a certain thinner PW, the resist solution PR is supplied to substantially the center of the surface of the wafer W. As shown in FIGS. 7B, 9D, and 11D, the supplied resist solution is supplied. PR diffuses to the radially outer peripheral side of the wafer W. Here, when a highly volatile thinner or the like is used as a solvent, when the resist solution is applied and diffused after the entire surface of the wafer W is wetted with the solvent PW, the solvent PW is used as the solvent. It will no longer vaporize in the surrounding area. When the film of the thinner PW that is a solvent disappears in the peripheral part of the wafer W, the resist liquid PR in the peripheral part is a thinner that is a solvent when the resist liquid PR is diffused from the radial center side to the outer peripheral side of the wafer W. The PW film tends to spread to the wetted portion, and the dried portion becomes difficult to apply the resist solution PR. Therefore, as shown in a region I surrounded by a dotted line in FIG. 11D, a region where the resist solution is not applied is generated, or the film thickness of the resist film is partially reduced, resulting in uneven film thickness. . In order to prevent such film thickness unevenness from occurring, a large amount of resist solution must be supplied.

  However, according to the resist coating method according to the present embodiment, as described above, not only the pre-wetting process can be performed substantially simultaneously in the first process, but also the pre-wetting process is performed in the first process. When performing at substantially the same time, the resist solution PR is applied before the thinner PW which is a solvent volatilizes. Therefore, when the resist solution PR diffuses to the outer peripheral side in the radial direction of the surface of the wafer W, the solvent P thinner as the solvent is not vaporized and dried in the peripheral portion of the wafer W, and the resist solution PR is transferred to the wafer W. It diffuses uniformly on the surface and does not cause film thickness unevenness. Therefore, there is an effect that the resist film can be formed without causing unevenness of film thickness without supplying a large amount of resist solution.

  Therefore, according to the resist coating method according to the present embodiment, a solvent supply step S0 for supplying a solvent onto the substantially center of a substantially stationary substrate (wafer), and a pre-wet treatment for performing a prewetting process after the solvent supply step S0. The first step S1 of rotating the substrate (wafer) at the first rotation speed while supplying the resist solution on the solvent at substantially the center of the substrate (wafer) without performing the wet processing step independently. In the first step, the solvent volatilizes on the substrate (wafer), causing a dry portion in the peripheral portion of the substrate (wafer). The resist solution to be applied does not occur in the dry part, and the resist solution can be efficiently applied to the entire surface of the substrate (wafer) with a smaller supply amount, and the resist is applied to the substrate (wafer). When It is possible to reduce the consumption of the resist solution.

  In the present embodiment, as shown in FIG. 7A, the resist solution PR is obtained at the point B immediately after the rotation speed of the wafer W is accelerated to the first rotation speed V1 in the first step. However, the resist solution PR does not directly diffuse the surface of the wafer W, but may diffuse the surface of the wafer W through the thinner PW that is a solvent. Therefore, the resist solution PR supplies thinner PW, which is a solvent, substantially on the center of the surface of the wafer W before the rotation speed of the wafer W accelerated to the first rotation speed V1 reaches the first rotation speed V1. If the viscosity of the thinner PW, which is a solvent, is extremely smaller than that of the resist solution PR, the supply of the resist solution PR is performed immediately before the wafer W in a substantially stationary state starts to be accelerated to the first rotational speed V1. You may start.

  Next, the resist coating method according to the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the examples.

In this example, the resist coating apparatus unit COT shown in the embodiment of the present invention was manufactured, and the effect was verified by performing an experiment using the resist coating apparatus COT.
(Example)
As an example, resist application processing based on the processing recipe of the resist application method according to the embodiment of the present invention shown in Table 1 is performed, and the amount of resist solution supplied in the first step S1 is 0.7 ml, 0 It was evaluated whether or not the distribution of the thickness of the applied resist film was uniform when it was reduced to 0.6 ml, 0.5 ml, 0.45 ml, and 0.4 ml. The determination of whether the film thickness distribution is uniform was confirmed by visual observation.

（比較例）
また、比較例として、表２に示した従来のレジスト塗布方法の処理レシピに基づくレジスト塗布処理を行い、実施例と同様に、第１の工程Ｓ１で供給するレジスト液の供給量を０．７ｍｌ、０．６ｍｌ、０．５ｍｌ、０．４５ｍｌ、０．４ｍｌと減少させた場合における、塗布されたレジスト膜の膜厚の分布が均一か否かの評価を行った。膜厚の分布が均一か否かの判定は、目視により確認した。

(Comparative example)
Further, as a comparative example, a resist coating process is performed based on the processing recipe of the conventional resist coating method shown in Table 2, and the amount of the resist solution supplied in the first step S1 is 0.7 ml as in the example. , 0.6 ml, 0.5 ml, 0.45 ml, and 0.4 ml, it was evaluated whether the thickness distribution of the applied resist film was uniform. The determination of whether the film thickness distribution is uniform was confirmed by visual observation.

実施例及び比較例におけるレジスト塗布を行った場合の、塗布されたレジスト膜の膜厚の分布が均一か否かの判定を行った結果を比較して、表３に示す。

Table 3 shows a comparison of the results of determining whether or not the distribution of the film thickness of the applied resist film is uniform when the resist application in Examples and Comparative Examples is performed.

実施例においては、表３に示すように、第１の工程Ｓ１で供給するレジスト液の供給量が０．７〜０．４５ｍｌの場合には、塗布されたレジスト膜の膜厚の分布を均一にすることができたが、第１の工程Ｓ１で供給するレジスト液の供給量が０．４ｍｌの場合には、塗布されたレジスト膜の膜厚の分布を均一にすることはできなかった。

In the example, as shown in Table 3, when the amount of the resist solution supplied in the first step S1 is 0.7 to 0.45 ml, the distribution of the thickness of the applied resist film is uniform. However, when the supply amount of the resist solution supplied in the first step S1 is 0.4 ml, the thickness distribution of the applied resist film cannot be made uniform.

  On the other hand, in the comparative example, as shown in Table 3, when the supply amount of the resist solution supplied in the first step S1 is 0.7 to 0.6 ml, the thickness distribution of the applied resist film is as follows. However, when the supply amount of the resist solution supplied in the first step S1 is 0.5 to 0.4 ml, the thickness distribution of the applied resist film is made uniform. I couldn't.

  From the above results, even in the range of 0.5 ml and 0.45 ml of resist solution supply range in which the resist film thickness could not be satisfactorily applied so far, the resist film thickness distribution was uniform. By performing the resist coating method according to the embodiment of the present invention, it is possible to perform good resist coating so that the film thickness distribution of the resist film can be made uniform. That is, it has been clarified that by performing the resist coating method according to the embodiment of the present invention, the resist solution can be efficiently applied to the entire surface of the wafer with a smaller amount of the resist solution supplied.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed. For example, in the above-described embodiment, the resist solution coating process has been described as an example. However, the present invention can be applied to coating solutions other than the resist solution, such as an antireflection film, an SOG (Spin On Glass) film, and an SOD. (Spin on Dielectric) The present invention can also be applied to a coating treatment of a coating solution for forming a film or the like. In the above-described embodiment, the solvent is a pre-wet solvent for performing the pre-wet treatment, but may be a solvent other than the pre-wet solvent, for example, a solvent for simply diluting the coating solution. It may also be a solvent for changing the wettability of the substrate and the coating liquid to the substrate, or a solvent for performing a treatment for the purpose of surface modification of the substrate. . Further, in the above-described embodiment, an example in which a coating process is performed on a wafer has been described. However, in the present invention, a substrate having another shape such as an FPD (flat panel display) other than a wafer or a photomask reticle is used. The present invention can also be applied to a substrate coating process made of other materials.

DESCRIPTION OF SYMBOLS 1 Application | coating development processing system 10 Cassette station 11 Processing station 12 Interface part 20 Cassette mounting base 20a Positioning protrusion 22 Main wafer transfer mechanism 25 Guide rail 46 Wafer transfer apparatus 47 Transfer base 48 Holding member 49 Cylindrical support body 50 Unit bottom plate 52 Spin Chuck 54 Drive motor 58 Flange member 60 Elevation drive means 62 Elevation guide means 64 Cooling jacket 86 Registration nozzle 88 Registration nozzle 90 Registration nozzle standby section 92 Registration nozzle scan arm 94 Guide rail 96 Vertical support member 100 Nozzle holder 101 Solvent nozzle 120 Rinse nozzle scan arm 122 Vertical support member 124 Rinse nozzle 130 Control unit 131 Resist supply unit 132 Solvent supply unit

COT Resist coating unit CR Wafer cassette DEV Development unit (Development unit)
G1, G2, G3, G4, G5 Processing unit group PR Resist liquid PW Thinner (solvent)
W wafer (substrate)

Claims (4)

A solvent supply step of supplying a solvent on the substantially center of the substantially stationary substrate;
After the solvent supply step, a first step of rotating the substrate at a first rotation speed while supplying a resist solution on the solvent substantially on the center of the substrate;
A second step of rotating the substrate at a second rotational speed lower than the first rotational speed after the first step;
And a third step of rotating the substrate at a third rotational speed that is lower than the first rotational speed and higher than the second rotational speed after the second step. The solvent is a solvent for pre-wetting the substrate,
The resist coating method according to claim 1, wherein in the first step, the substrate is pre-wet treated by diffusing the solvent from a center side to an outer peripheral side of the substrate.   The resist coating method according to claim 1, wherein a viscosity of the solvent is smaller than a viscosity of the resist. In the first step, the supplied resist solution is diffused from the center side to the outer peripheral side of the substrate,
In the second step, the shape of the diffused resist solution is adjusted,
The resist coating method according to any one of claims 1 to 3, wherein in the third step, the resist solution on the substrate is shaken off and dried.

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