JP6374373B2 - Spin coater - Google Patents

Description

  Embodiments described herein relate generally to a spin coating apparatus and a spin coating method.

The spin coating method (spin coating method) is a method of forming a coating film by dropping a coating solution onto a substrate and then rotating the substrate at a rotational speed for determining the film thickness of the coating solution. In the conventional spin coating method, for example, the coating solution is dropped while rotating the substrate, so that the coating solution is spread on the surface of the substrate to form a coating film. However, in this method, a large amount of coating solution is required to form a coating film, and when the substrate area becomes large, the coating solution cannot be applied to the end portion of the substrate or the vicinity of the end portion. Therefore, in the conventional method, various conditions such as the number of rotations of the substrate and the discharge speed of the coating liquid are adjusted as necessary. On the other hand, when the wettability between the substrate and the coating solution is poor, the coating solution is repelled by the substrate, resulting in uneven coating of the coating solution, and worsening the uniformity of the coating solution thickness. . In addition, when there is a step in the substrate, there is a possibility that uneven coating is induced. In order to reduce the amount of the coating solution used, a method has been proposed in which the substrate is wetted with a pre-wetting solution before the coating solution is applied to improve the wettability. Although this method can alleviate the problem of a large amount of coating liquid used and the problem of poor film thickness uniformity of the coating liquid, these problems still remain. In the case of using a pre-wet liquid, it is required to obtain a merit that is commensurate with the cost increase due to the use of the pre-wet liquid.

JP-A-8-330206 JP 2004-64071 A JP-A-5-123632 JP-A-5-243140 Japanese Patent No. 2638969 JP 2000-157922 A JP 2000-279874 A JP 2006-156565 A Japanese Patent No. 4745358 JP 2004-179614 A Japanese Patent No. 4578993 Japanese Patent No. 4621613 Japanese Patent No. 4718584 Japanese Patent No. 3302603 Japanese Patent No. 3330324 Japanese Patent No. 3335928 Japanese Patent No. 352759 JP 2001-307984 A JP 2002-307007 A Japanese Patent No. 4749829 Japanese Patent No. 4749830 JP 2007-299941 A Japanese Patent No. 4805769 JP 2008-263986 A JP 2009-78250 A JP 2010-153907 A JP 2011-67810 A JP 2011-230113 A JP 2012-24705 A

Provided are a spin-coating apparatus and a spin-coating method capable of forming a coating film in a wider range while reducing the dripping amount of the coating liquid.

According to one embodiment, the spin-coating apparatus includes a pre-wet liquid supply unit that drops a pre-wet liquid onto the substrate, a coating liquid supply unit that drops the liquid onto the substrate, a motor that rotates the substrate, A pre-wet liquid supply unit, a coating liquid supply unit, and a control unit that controls the operation of the motor, the pre-wet liquid supply unit drops the pre-wet liquid onto the substrate, and the motor By rotating the substrate, the pre-wet liquid is spread on the surface of the substrate, and after spreading the pre-wet liquid on the surface of the substrate, the substrate is rotated at the first rotation speed (rpm) by the motor. However, the coating liquid is spread to a position inside the edge of the substrate by dropping the coating liquid onto the substrate by the coating liquid supply unit at a first discharge rate by a first dropping amount. After dripping the coating liquid by the first dripping amount, the coating liquid supply unit rotates the substrate at a second rotational speed (rpm) smaller than the first rotational speed by the motor. By dropping the coating liquid onto the substrate by a second dropping amount at a second discharge speed that is faster than the first discharge speed, the coating liquid is spread to the end portion of the substrate or near the end portion, and the coating is applied. After the liquid is discharged at the second discharge speed, the coating liquid supply unit supplies the coating liquid at a third discharge speed that is slower than the second discharge speed, and the first drop amount and the second First and second discharges discharge a third drop amount smaller than the sum of the drop amounts onto the substrate, and the coating liquid supply unit discharges the coating liquid at the first and second discharge speeds, respectively. Of the time, the second discharge time is 0.1 seconds or less, Coating solution supply unit, of said first and second drop amount, the second dropping amount, or less 0.1 ml.

It is sectional drawing (1/2) which shows the flow of the spin coating method of 1st Embodiment. It is sectional drawing (2/2) which shows the flow of the spin coating method of 1st Embodiment. It is the schematic which shows the structure of the spin coater of 1st Embodiment. It is a table | surface for demonstrating the specific example of the spin coating method of 1st Embodiment. It is a graph for demonstrating the specific example of the spin coating method of 1st Embodiment. It is a graph for demonstrating the 1st example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 2nd example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 3rd example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 4th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 5th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 6th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 7th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 8th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 9th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 10th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 11th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 12th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 13th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 14th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 15th example of the spin coating method of 2nd Embodiment. It is a graph for demonstrating the 16th example of the spin coating method of 2nd Embodiment. It is a table | surface for demonstrating the specific example of the spin coating method of 2nd Embodiment. It is a table | surface for demonstrating another specific example of the spin coating method of 2nd Embodiment. It is the table | surface which showed the experimental result at the time of implementing the spin coating method of 2nd Embodiment.

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

(First embodiment)
1) Spin coating method of the first embodiment FIGS. 1 and 2 are cross-sectional views showing the flow of the spin coating method of the first embodiment.

First, as shown in FIG. 1 (a), a pre-wet liquid 2 is dropped onto the center of the substrate 1 to obtain the substrate 1
Is rotated to spread the pre-wet liquid 2 on the surface of the substrate 1. Pre-wet liquid 2 is
The liquid is dropped from the nozzle of the pre-wet liquid supply unit 11 to the center of the substrate 1.

The substrate 1 is, for example, a circular substrate such as a semiconductor wafer, but may be a rectangular substrate such as a photomask substrate or a liquid crystal display substrate, or may be a substrate having another polygonal shape. In the present embodiment, a step is formed on the surface of the substrate 1 by a pattern such as a trench, a transistor, a memory cell, and a wiring.

The pre-wet liquid 2 is preferably a liquid that is compatible with the coating liquid 3, has a lower viscosity than the coating liquid 3, and has a vapor pressure at 23 ° C. of 10 hPa or less. The reason why the vapor pressure of the pre-wet liquid 2 is desirably low is that when the vapor pressure of the pre-wet liquid 2 is high, a large amount of the pre-wet liquid 2 evaporates during the coating process of the coating liquid 3.

Next, as shown in FIG. 1 (b), while rotating the substrate 1 at the first rotation speed N _1, dropping the coating liquid 3 first in the central portion of the substrate 1 is wet with the pre-wet liquid 2 By dripping only the amount M ₁ , the coating liquid 3 is spread on the surface of the substrate 1. The coating liquid 3 is supplied from the nozzle of the coating liquid supply unit 12 to the substrate 1.
It is dripped at the center of the.

Examples of the coating liquid 3 include a photoresist, an antireflection material, a photoresist protective material, a resist pattern shrink material, a protective material for immersion exposure, polyimide, SOG (spin-on-glass), a low-k material, and a sol-gel material. It is done. Further, the coating liquid 3 may be a photoresist lower layer material, a photoresist upper layer material, a planarizing material, an embedding material, or the like.

In the present embodiment, the first rotation speed N _{1 is set} to a rotation speed at which the coating liquid 3 cannot substantially spread over the entire substrate 1. Specifically, the first rotation speed N _{1 is set} to a rotation speed at which the coating liquid 3 receives sufficient air resistance (due to the generation of turbulent flow) at the outer peripheral portion of the substrate 1. For example, the substrate 1 has a diameter of 30
In the case of a 0 mm wafer, it is desirable to set the _first rotational speed N ₁ to 3000 rpm or more. Depending on the material of the coating liquid 3, the first rotational speed N ₁ may be set to 2000 rpm or more. Further, in the present embodiment, the first drop amount M ₁ is set to an amount that is substantially insufficient to uniformly apply the coating liquid 3 to the entire substrate 1.

By setting the first rotation speed N ₁ at a high speed as described above, a state in which the outer peripheral portion of the substrate 1 is not substantially coated with the coating liquid 3 is created as shown in FIG. Can do. The reason is that the advance of the coating liquid 3 stops when the coating liquid 3 receives sufficient air resistance. If there is a step on the surface of the substrate 1, the progress of the coating liquid 3 is likely to stop.

By stopping the progress of the coating liquid 3, the coating liquid 3 is transferred to the end portion 1 of the substrate 1 as shown in FIG.
It will be in the state which extended to the position inside a. Then, at the end of the coating liquid 3, as shown by reference numeral 3 a, a swell occurs due to the accumulated coating liquid 3. When the first rotation speed N ₁ is increased, the position where the coating liquid 3 stops moving moves closer to the center of the substrate 1, the time until reaching the limit point is shortened, and the coating liquid 3 rises. The amount gets bigger. In addition, the coating liquid 3 in the swelled portion is sequentially scattered on the outer peripheral portion of the substrate 1 and the outside.

  Here, the pre-wet liquid 2 in the stage of FIG.

Since the coating liquid 3 is a liquid for forming a coating film, the viscosity is generally high. For this reason, the coating liquid 3 is generally difficult to spread on the substrate 1 and is easily affected by air resistance, so that the end portion of the coating liquid 3 is raised when the substrate 1 is rotated at a high speed. On the other hand, as the pre-wet liquid 2, a liquid having a low viscosity can be used so that the end portion of the pre-wet liquid 2 does not swell even when the substrate 1 rotates at high speed. FIG. 1 (c) shows a state in which no swell is generated at the end of the pre-wet liquid 2.

It is desirable that the end portion of the pre-wet liquid 2 is always closer to the outer peripheral portion side of the substrate 1 than the end portion of the coating liquid 3. The reason is that if the end of the pre-wet liquid 2 is overtaken by the end of the coating liquid 3,
This is because the wettability improving effect cannot be obtained at the overtaken location. This can be realized, for example, by increasing the rotation time of the pre-wet liquid 2 and delaying the dropping time of the coating liquid 3. If the vapor pressure of the pre-wet liquid 2 is high, after the pre-wet liquid 2 reaches the outer periphery of the substrate 1, it begins to dry from the outer periphery of the substrate 1 during the rotation of the substrate 1. Since it moves backward toward the center of 1, the end of the prewetting liquid 2 is eventually overtaken by the end of the coating liquid 3.

The end portion of the pre-wet liquid 2 is the end portion of the substrate 1 when the first dropping amount M ₁ of the coating liquid 3 is dropped or when the rotation at the first rotation speed N ₁ is finished. (Outermost part) 1a
It is desirable that the prewetting liquid 2 does not recede due to drying. Thereby, at the stage where the dropping of the second dropping amount M ₂ of the coating liquid 3 is started, the end portion of the pre-wet liquid 2 reaches the end portion 1a of the substrate 1 and is held there.

Next, as shown in FIG. 2A, the substrate 1 is moved to a second rotational speed N _{2 that} is smaller than the first rotational speed N _1.
The coating liquid 3 is dropped on the central portion of the substrate 1 by the second dropping amount M ₂ while rotating at
The coating liquid 3 is further spread on the surface of the substrate 1. It is desirable that the dropping of the first dropping amount M ₁ of the coating solution 3 and the dropping of the second dropping amount M ₂ of the coating solution 3 are continuously performed.

When the number of rotations of the substrate 1 is decreased from the first number of rotations N ₁ to the second number of rotations N ₂ , the air resistance received by the coating solution 3 is weakened, and the coating solution 3 is likely to travel toward the end 1 a of the substrate 1. Become. In this state, by newly dropping the second dropping amount M ₂ of the coating liquid 3, the coating liquid 3 that has already been dropped onto the substrate 1 is pushed out. As a result, the coating liquid 3 spreads to the end 1a of the substrate 1 or the vicinity of the end 1a.

At the end of the coating solution 3, as shown in FIG. 2A, the coating solution 3 advances while the swell of the coating solution 3 is reduced. Therefore, the remaining most of the outer peripheral portion of the substrate 1 can be applied with the coating liquid 3 at the rising portion. Therefore, in the present embodiment, it is not necessary to increase the second drop amount M _2, and it is sufficient that the second drop amount M ₂ is less than the first drop amount M ₁ .

The pre-wet liquid 2 is applied to the substrate 1 until the coating liquid 3 reaches the end 1 a of the substrate 1.
It is desirable to hold up to the end 1a. This is because the effect of improving the wettability by the pre-wet liquid 2 is maintained up to the end 1 a of the substrate 1. Therefore, it is desirable to employ a liquid having a low vapor pressure as the pre-wet liquid 2, for example, a liquid having a vapor pressure of 10 hPa or less at 23 ° C. is desirable. In this case, the pre-wet liquid 2 is finally pushed out of the substrate 1 by the coating liquid 3.

Next, as shown in FIG. 2 (b), the substrate 1 is rotated at a third rotational speed for determining the film thickness of the coating solution 3.
Is rotated to control the film thickness of the coating liquid 3 to a predetermined value. Note that before the substrate 1 is rotated at the third rotation number, for example, the substrate 1 may be rotated at a low rotation number of about 100 rpm and reflow may be performed for several seconds. Also, the extrusion of the pre-wet liquid 2 by the coating liquid 3 is shown in FIG.
You may perform not in the step of a) but in the step of FIG.2 (b).

Thereafter, in this embodiment, the edge of the coating liquid 3 is cut, and the solvent of the coating liquid 3 is evaporated by baking. Thus, a coating film is formed from the coating liquid 3.

  Here, the effect of the first embodiment will be described.

In the spin coating method, as the size of the substrate 1 increases, the coating liquid 3 is rotated when the substrate 1 is rotated.
Is more susceptible to air resistance. In particular, since the air resistance is larger at the outer peripheral portion of the substrate 1 than at the central portion of the substrate 1, the coating liquid 3 is increased at the outer peripheral portion of the substrate 1 as the rotational speed of the substrate 1 increases.
Becomes difficult to spread. This problem cannot be avoided even when the substrate 1 is previously wetted with the pre-wet liquid 2.

Therefore, in the present embodiment, when the coating liquid 3 is dropped after the pre-wet liquid 2 is dropped, the coating liquid 3 is first dropped while rotating the substrate 1 at the first high speed N ₁ . And substrate 1
When the advance of the coating liquid 3 stops at a position inside the end 1a, the number of rotations of the substrate 1 is switched to the second low speed N ₂ and the coating liquid 3 is dropped. As a result, it is possible to form the coating film by applying the coating liquid 3 to the end 1a of the substrate 1 or the vicinity of the end 1a while keeping the amount of the coating liquid 3 dropped to a small amount. The dropping amount of the coating liquid 3 is, for example, due to scattering by making the second dropping amount M ₂ sufficiently smaller than the first dropping amount M ₁ or by appropriately setting the switching timing of the rotation speed of the substrate 1. It can be reduced by reducing the waste of the coating liquid 3.

Further, in the present embodiment, such a coating process of the coating liquid 3 is performed by applying the substrate 1 to the pre-wet liquid 2.
Therefore, the coating liquid 3 having good film thickness uniformity can be applied to the end 1a of the substrate 1 or the vicinity of the end 1a.

The spin coating method of this embodiment is, for example, a coating solution 3 having a viscosity of 0.1 to 1000 mPa · s.
However, the viscosity of the coating liquid 3 may be outside this range. The coating liquid 3 may be composed of an organic material or an inorganic material.

2) Spin coating apparatus according to the first embodiment FIG. 3 is a schematic diagram showing the configuration of the spin coating apparatus according to the first embodiment. The above-described spin coating method can be executed by, for example, the spin coating apparatus shown in FIG.

3 includes a pre-wet liquid supply unit 11, a coating liquid supply unit 12, and a holding unit 1.
3, a rotating shaft 14, a motor 15, a vacuum line 16, a suction source 17, and a control unit 18.

In FIG. 3, the wafer (substrate) 1 is placed on the holding unit 13 and held horizontally. The holding unit 13 is fixed to the rotating shaft 14 and is connected to the motor 15 via the rotating shaft 14. The motor 15 is a rotational drive source that rotates the wafer 1 by rotationally driving the holding unit 13 about a rotational axis L parallel to the vertical direction. The motor 15 is configured such that the rotation speed (rotation speed) is variable.

The wafer 1 has a first surface corresponding to the front surface and a second surface corresponding to the back surface. FIG. 3 shows a state in which the coating film 4 is formed on the first surface of the wafer 1 having a step. The wafer 1 is held by the holding unit 13 such that the second surface is in contact with the holding unit 13. At this time, the wafer 1 is held by the holding unit 13 so that the center of the wafer 1 is on the rotation axis L.
Placed on.

The holding unit 13 is connected to the suction source 17 via the vacuum line 16. The wafer 1 placed on the holding unit 13 is held by vacuum-sucking the second surface with a suction force by the suction source 17.

The coating solution supply unit 12 is a device that supplies the coating solution 3 to the wafer 1 held by the holding unit 13. The coating liquid supply unit 12 has a nozzle 1 that opens downward to the free end 12b of the arm 12a so that the coating liquid 3 is dropped onto the arm 12a and the wafer 1 held by the holding unit 13.
2c. Further, the coating liquid supply unit 12 is connected to the coating liquid supply pipe 12d on the arm 12a.
And a discharge control device 12e that is arranged between the arm 12a and the coating liquid supply source 12f and that adjusts the flow rate of the coating liquid 3. The discharge control device 12e is realized by a device such as a pressure-feed pump.

An arm moving mechanism (not shown) is connected to the arm 12 a of the coating liquid supply unit 12. The arm moving mechanism has a function of moving the nozzle 12 c from the storage location of the nozzle 12 c away from the wafer 1 to the upper part of the central portion of the wafer 1 where the coating liquid 3 is dropped. The arm moving mechanism further has a function of adjusting the height of the nozzle 12 c at the dropping position of the coating liquid 3.

The pre-wet liquid supply unit 11 is a device that supplies the pre-wet liquid 2 to the wafer 1 held by the holding unit 13. Similar to the coating liquid supply unit 12, the prewet liquid supply unit 11 includes an arm 11a, a free end 11b, a nozzle 11c, a prewet liquid supply pipe 11d, a discharge control device 11e, and a prewet liquid supply source. 11f and an arm moving mechanism (not shown).

In this embodiment, for example, a resist film is formed as the coating film 4 by using a photoresist as the coating liquid 3. In this case, as the pre-wet liquid 2, it is desirable to use a liquid compatible with the photoresist, such as a solvent for the photoresist.

The control unit 18 is configured by, for example, a computer, and controls the operation of each unit of the spin coater. The control unit 18 has a function of facilitating the processing of the wafer 1 by, for example, programming the processing procedure of the wafer 1 by an operator.

The control unit 18 includes, for example, the rotation speed and rotation time of the motor 15, the dropping amount and discharging speed of the coating liquid 3 by the coating liquid supply unit 12, the dropping amount and discharging speed of the pre-wet liquid 2 by the pre-wet liquid supply unit 11, and the coating The operation of the arm moving mechanism of the liquid supply unit 12 and the pre-wet liquid supply unit 11 is controlled. For example, the above-described rotation driving method includes the pre-wet liquid supply unit 11 and the coating liquid supply unit 1.
2 and by controlling the operation of the motor 15 by the control unit 18.

3) Specific Example of Spin Coating Method of First Embodiment FIGS. 4 and 5 are a table and a graph for explaining a specific example of the spin coating method of the first embodiment, respectively. FIG. 4 shows an example of a recipe for the spin coating method of the first embodiment, and FIG. 5 shows an example of a sequence for operating the spin coater with this recipe. In the experiment relating to this recipe, the coating solution 3 having a viscosity of 1 mPa · s was used.

First, the pre-wet liquid supply unit 11 drops the pre-wet liquid 2 on the central portion of the wafer 1 by the dropping amount M _p (step S1). The symbol T _p1 represents the dropping time during which the pre-wet liquid 2 is dropped by the dropping amount M _p . The dripping amount M _p is, for example, 3 ml.

Then, by rotating the wafer 1 at a rotational speed N _p by a motor 15, extending the pre-wet liquid to the surface of the wafer 1 (step S2). The symbol T _p2 represents the rotation time of the wafer 1 at the rotation speed N _p . The rotation speed N _p is, for example, 1000 to 4000 rpm, and the rotation time T _p 2 is, for example, 0.1 to 3 s (seconds).

When a liquid having a high vapor pressure is used as the pre-wet liquid 2, the coating liquid 3 becomes the end 1 a of the wafer 1.
In some cases, the pre-wet liquid 2 evaporates before reaching the surface of the wafer 1, resulting in uneven coating on the outer periphery of the wafer 1. For this reason, it is desirable that the pre-wet liquid 2 is maintained up to the end 1 a of the wafer 1 until the coating liquid 3 reaches the end 1 a of the wafer 1. Therefore, the pre-wet liquid 2 is preferably a liquid that is compatible with the coating liquid 3, has a lower viscosity than the coating liquid 3, and has a vapor pressure at 23 ° C. of 10 hPa or less.

Next, while the wafer 1 is rotated at the first rotation speed N ₁ by the motor 15, the coating liquid 3 is dropped by the first dropping amount M ₁ onto the center of the wafer 1 by the coating liquid supply unit 12. The coating liquid 3 is spread on the surface of the wafer 1 (step S3). A symbol T ₁ represents the rotation time of the wafer 1 at the _first rotation speed N ₁ .

Here, the first rotation speed N ₁ is set to a rotation speed at which the first dropping amount M ₁ of the coating liquid 3 does not spread uniformly over the entire wafer 1 due to air resistance. For example, when the diameter of the wafer 1 is 300 mm, the first rotation speed N ₁ is set to 2000 to 4000 rpm, and the first dropping amount M ₁ is set to 0.3 ml. The first dropping amount M ₁ of the coating liquid 3 is applied to the wafer 1 by air resistance.
The state that does not spread uniformly over the whole is, for example, a state as shown in FIG.

Next, the coating liquid 3 is applied to the central portion of the wafer 1 by the coating liquid supply unit 12 while the wafer 1 is rotated by the motor 15 at a _second rotational speed N ₂ smaller than the first rotational speed N _2. By dropping the amount M ₂ , the coating liquid 3 is further spread on the surface of the wafer 1 (step S4). T
2 represents the rotation time of the wafer 1 at the _second rotation speed N ₂ .

The dropping of the first dropping amount M ₁ of the coating liquid 3 and the dropping of the second dropping amount M ₂ of the coating liquid 3 may be performed continuously. Further, the second dropping amount M ₂ may be smaller than the first dropping amount M ₁ and is set to 0.1 ml, for example. In this case, the total dropping amount M ₁ + M ₂ of the coating liquid 3 is 0.4 ml. Further, the second rotation speed N ₂ is set to 1000 to 3000 rpm, for example.

The symbol V represents the discharge speed (discharge amount per unit time) of the coating liquid 3. In the dropping of the first and second dropping amounts M ₁ and M ₂ of the coating liquid 3, the discharge speed of the coating liquid 3 is M ₁ / T ₁ , respectively.
It is defined as M ₂ / T _2. Hereinafter, the former is referred to as a first discharge speed, and the latter is referred to as a second discharge speed. In this recipe, the first discharge speed is equal to the second discharge speed, but the first discharge speed is the second
It is desirable that it is slower than the discharge speed. Thereby, it is possible to take a long time to drop the first dropping amount M ₁ of the coating liquid 3 and increase the swell of the end portion of the coating liquid 3. A specific example in which the first discharge speed is made slower than the second discharge speed will be described in the second embodiment.

Next, the reflow process is performed by rotating the wafer 1 at the rotation speed N ₃ by the motor 15 (step S5). Reference symbol T ₃ represents the rotation time of the wafer 1 at the rotation speed N ₃ . By this reflow process, the film thickness uniformity of the coating liquid 3 applied on the wafer 1 is improved. Note that the reflow process may be omitted.

Next, the wafer 1 is rotated at the rotation speed N ₄ for determining the film thickness of the coating liquid 3 by the motor 15 (step S6). Thereby, the film thickness of the coating film 3 coated on the wafer 1 is controlled to a desired value. Reference symbol T ₄ represents the rotation time of the wafer 1 at the rotation speed N 4. Rotational speed N
₄ corresponds to the third rotational speed described above.

Thereafter, in this recipe, the edge of the coating liquid 3 is cut with a thinner. Further, the wafer 1 is automatically conveyed to a hot plate, and the wafer 1 is baked by the hot plate to evaporate the solvent of the coating liquid 3. Further, the baked wafer 1 is cooled. Thus, the coating liquid 3
Thus, the coating film 4 is formed.

Examples of the coating liquid 3 include silazanes such as polysilazane and siloxanes such as polysiloxane in addition to the above-described examples. Specific examples of the former include perhydropolysilazane (PHPS) composed only of elements of Si, N, and H, and specific examples of the latter include S
Examples thereof include hydrogensilsesquioxane (HSQ) composed only of i, O, and H elements.

Typical examples of the pre-wet liquid 2 include cyclohexanone for resists and di-n-butyl ether for silazanes and siloxanes.
Another example of is terpenes. Terpenes generally have a vapor pressure of 6 hPa or less at 23 ° C. and a vapor pressure lower than that of di-n-butyl ether. Accordingly, the terpenes are less likely to evaporate during the coating process of the coating liquid 3 and are suitable for use as the pre-wet liquid 2. Examples of terpenes include α-pinene, β-pinene, p-
Menthane, d-limonene, dipentene, 1,8-cineole and the like can be mentioned. The pre-wet liquid 2 may be a mixture containing terpenes. The pre-wet liquid 2 is
A liquid other than terpenes may be used as long as the liquid has a low vapor pressure such as terpenes.

Next, the process time of the pre-wet liquid 2 and the coating liquid 3 will be described. For example, substrate 1
3 ml of di-n-butyl ether or α-pinene is dropped as the prewetting liquid 2 in the center of the substrate, the rotation speed N _p is set to 1000 rpm, and the substrate 1 is rotated for the rotation time T _p . next,
At the same time as increasing the rotational speed N ₁ to 2500 rpm, the coating liquid 3 having a viscosity of 1 mPa · s is dropped. At this time, when di-n-butyl ether is used, if T _p is set to a time exceeding 0.1 s, uneven coating occurs at the outer peripheral portion of the substrate. On the other hand, in the case of using α- pinene may be better T _p is long improved as the film thickness uniformity without the occurrence of uneven coating, a T _p 0.
A good coating film 4 can be formed by setting it to 5 s or more (more preferably 1 s or more).

Time to extend the pre-wet liquid 2 T _p and then the coating liquid 3 total time to completion of the dropwise addition time can reduce the amount of the coating liquid 3 by setting a long time. This total time is, for example, about 1.5 s or more.

As described above, in the present embodiment, when the coating liquid 3 is dropped after the pre-wet liquid 2 is dropped, first, the coating liquid 3 is dropped while the substrate ₁ is rotated at the _first rotation speed N _1. In addition,
The coating liquid 3 is dropped while rotating the substrate 1 at a second rotational speed N ₂ smaller than the rotational speed N ₁ .
Thereby, according to this embodiment, it becomes possible to form the coating film 4 in a wider range, while reducing the dripping amount of the coating liquid 3.

(Second Embodiment)
1) Spin coating method of the second embodiment FIGS. 6 to 21 are graphs for explaining first to sixteenth examples of the spin coating method of the second embodiment, respectively.

In the second embodiment, when the coating liquid 3 is dropped while rotating the substrate 1 at the first rotation speed N ₁ , the coating liquid 3 is discharged onto the substrate 1 at the first discharge speed V ₁ . Further, in the present embodiment, when the coating liquid 3 is dropped while rotating the substrate 1 at the second rotational speed N ₂ smaller than the rotational speed N ₁ , the coating liquid 3 is made faster than the first discharge speed V _1. discharging the substrate 1 at a faster second discharge speed V _2. Hereinafter, various examples of the spin coating method of the second embodiment will be described.

The following examples will be described on the assumption that a wafer having a diameter of 300 mm is used as the substrate 1.
However, the present embodiment can be applied to other substrates 1, for example, when using a substrate 1 having a smaller diameter, or when using a substrate 1 having a large size such as a liquid crystal display substrate. is there.

FIG. 6 is a graph for explaining a first example of the spin coating method of the second embodiment. FIG.
The horizontal axis indicates time, and the vertical axis in FIG. 6 indicates the rotation speed of the substrate 1 and the discharge speed of the coating liquid 3.

In FIG. 6, first, the pre-wet liquid 2 is dropped within the time T _p1 , and then the substrate 1 is rotated at the rotation speed N _p within the time T _p2 to spread the pre-wet liquid 2 on the substrate 1. For example, the rotational speed N _p is comprehensively determined in the range of 1000 to 4000 rpm based on the drying property of the pre-wet liquid 2 and the compatibility with the coating liquid 3. In FIG. 6, the substrate 1 is also within time T _p1 .
You may make it rotate.

In FIG. 6, next, while the substrate 1 is rotated at the first rotation speed N ₁ , the coating liquid 3 is dropped at the first discharge speed V ₁ by the first drop amount M ₁ . Next, while the substrate 1 is rotated at the second rotation speed N ₂ , the coating liquid 3 is dropped by the second drop amount M ₂ at the second discharge speed V ₂ that is faster than the first discharge speed V _1. . In FIG. 6, after the first discharge is performed at the first discharge speed V ₁ , the second discharge is continuously performed at the second discharge speed V ₂ . A second discharge may be performed after the discharge is temporarily stopped after the discharge (see FIG. 7).

In FIG. 6, it is desirable that the dropping amount of the coating liquid 3 satisfies M ₁ > M ₂ . Thereby, the in-plane uniformity of the film thickness of the coating liquid 3 can be improved by finally discharging a small amount of the coating liquid 3 at a high speed. The first rotation speed N ₁ is desirably set in consideration of the concentration and viscosity of the coating liquid 3, and is set to, for example, 500 to 4000 rpm. Further, it is desirable that the second rotation speed N ₂ is lower than the first rotation speed N ₁ .

In FIG. 6, the second rotation speed N ₂ may be set to the reflow rotation speed. In this case, for example, the second rotation speed N ₂ is set to 100 to 500 rpm, and the time T ₂ is set to 1 to 5 seconds. The reflow has an effect of increasing the in-plane uniformity of the film thickness of the coating liquid 3. Therefore, in order to incorporate this effect, dropping of the coating liquid 3 may be stopped while the substrate 1 is being rotated at the second rotation speed N ₂ (see FIG. 8). Further, the second rotation speed N ₂ may be set to a value higher than 500 rpm (for example, 1000 rpm or more).

6-8, for example, the first discharge speed V ₁ is set to ₁ ml / s or less and the second discharge speed V ₂ is set to 1.5 ml / s or more, but other values are set. Also good. In FIGS. 6 and 8, the discharge speed of the coating liquid 3 is changed from V ₁ to V ₂ almost simultaneously with the change of the rotation speed of the substrate 1 from N ₁ to N _2. The timing and the change timing of the discharge speed do not need to match. For example, the discharge speed may be changed from V ₁ to V ₂ while the substrate 1 is rotated at the first rotation speed N ₁ . Similarly, the discharge speed may be changed from V ₁ to V ₂ while the substrate 1 is rotated at the second rotation speed N ₂ .

In FIG. 6, next, the substrate 1 is rotated at a rotational speed N ₄ for a time T ₄ . The rotational speed N ₄ is the coating film 3
Of the film thickness. Here, the rotational speed N ₄ is set larger than the rotational speed N ₂ .
The rotation speed N ₄ may be set smaller than the rotation speed N ₂ .

Thereafter, in the process of FIG. 6, edge cutting and back surface cleaning are performed with a rinsing liquid, and the rinsing liquid is dried by continuing the rotation of the substrate 1 at an arbitrary rotation number. There is no restriction on the number of rotations for drying.

In order to shorten the process time, the process of the second rotation speed N _{2 and} the process of the film thickness determination rotation speed N ₄ can be performed together (see FIG. 9). In FIG. 9, the coating liquid 3 is dropped at the _first discharge speed V ₁ while rotating the substrate 1 at the first rotation speed N ₁ , and then the substrate 1 is rotated at the film thickness determination rotation speed N _4.
The coating liquid 3 is dropped at the second discharge speed V ₂ while rotating at. Then, while the substrate 1 is rotated at the film thickness determination rotation speed N ₄ , the discharge of the coating liquid 3 is stopped and the rotation of the substrate 1 is continued as it is.

  Next, the spin coating method shown in FIGS. 10 to 13 will be described.

In FIG. 10, the discharge of the coating liquid 3 at the _first discharge speed V ₁ is started while the substrate 1 is being rotated at the first rotation speed N ₁ . The rotation start timing and the discharge start timing may be slightly different depending on the type of the spin coater and the programming conditions. Even in such a case, by setting the discharge speed according to the number of rotations, the coating film 4 having excellent in-plane film thickness uniformity can be formed while reducing the amount of the coating liquid 3 dropped and the amount of the chemical liquid. Can do.

Further, as shown in FIG. 11, the rotation speed N _p and the first rotation speed N ₁ are set to the same value, the substrate 1 is continuously rotated during these periods, and the substrate 1 is rotated at the rotation speed N _p. While rotating at (= N ₁ ), the discharge of the coating liquid 3 at the _first discharge speed V ₁ may be started.

In addition, as shown in FIG. 12, the substrate 1 is first rotated from the middle of rotating at the _first rotation speed N 1.
The discharge at the second discharge speed V ₁ may be started and the discharge at the second discharge speed V ₂ may be completed while the substrate 1 is being rotated at the _second rotation speed N ₂ .

In addition, as shown in FIG. 13, before starting to rotate the substrate 1 at the first rotation speed N ₁ , the discharge at the first discharge speed V ₁ is started and the substrate 1 is rotated at the second rotation speed N ₂ . Second after finishing
The discharge at the discharge speed V ₂ may be terminated.

As described above, in this embodiment, the rotation timing of the substrate 1 and the discharge timing of the coating liquid 3 may be shifted. Moreover, in this embodiment, you may use combining the example of FIGS.

  Next, the spin coating method of FIGS. 14 to 16 will be described.

In this embodiment, it is not necessary to discharge the coating liquid 3 when the rotation speed of the substrate 1 is constant. For example, as shown in FIG. 14, discharge at the first discharge speed V ₁ may be performed while increasing the rotation speed of the substrate 1. Further, contrary to FIG. 14, discharge at the first discharge speed V ₁ may be performed while the rotation speed of the substrate 1 is decreased. This also applies with respect to the discharge by the second discharge speed V _2.

Further, the change from the _first discharge speed V ₁ to the second discharge speed V ₂ may be performed slowly as shown in FIG. 15 or stepwise as shown in FIG.

  Next, the spin coating method shown in FIGS. 17 to 19 will be described.

In FIGS. 17 and 18, the substrate 1 is rotated at the second rotational speed N ₂ and then rotated at the rotational speed N ₃ . The rotational speed N ₃ may be smaller or larger than the second rotational speed N ₂ . The rotation process at the rotation speed N ₃ may be a reflow process. 17 and 18, the substrate 1 is rotated at the rotation speed N ₃ and then rotated at the film thickness determination rotation speed N ₄ . It should be noted that the discharge of the coating liquid 3 at the _second discharge speed V ₂ may be terminated at the _second rotation speed N ₂ as shown in FIG.
As shown in FIG. ₄ , the rotation may continue until the rotation speed is N ₃ .

On the other hand, in FIG. 19, prior to rotating the substrate 1 at the first rotation speed N _1, at a rotational speed N ₅ time T ₅
Just rotate. The discharge at the first discharge speed V ₁ starts in the middle of rotating the substrate 1 at the rotation speed N ₅ and continues even after the rotation speed of the substrate ₁ is switched to the first rotation speed N ₁ . In addition,
In FIG. 19, the discharge at the first discharge speed V ₁ may be started after the rotation at the rotation speed N ₅ is finished.

  Next, the spin coating method of FIGS. 20 and 21 will be described.

Figure 20 In the coating liquid 3 while rotating the substrate 1 at the second rotational speed N ₂ of the second discharge speed V ₂
Then, the coating liquid 3 is discharged at the third discharge speed V ₃ while maintaining the rotation speed of the substrate 1 at the second rotation speed N ₂ . In FIG. 20, the third discharge speed V ₃ is set to a speed slower than the second discharge speed V ₂ . The third discharge velocity V ₃ of the may be slower and faster than the first discharge speed V _1, may be the first discharge speed V ₁ and the same speed.

Here, the effect of the process of FIG. 20 will be described. 6 to 19, the discharge speed of the coating liquid 3 is changed from the _first discharge speed V ₁ to the second discharge speed V _{2. When} the discharge speed is changed during the process, the coating liquid is changed. Since the pressure in the pipe changes, the discharge state of the coating liquid 3 may become unstable. For example, when controlling the start and end of discharge by opening and closing a valve, the coating liquid 3 is unintentionally discharged or sucked up due to a pressure change in the pipe or a volume change in the pipe due to the valve opening and closing. Sometimes. When such a phenomenon occurs, bubbles may be sucked up from the nozzle 12c into the coating liquid 3 pipe, and the discharge of the coating liquid 3 may become unstable, leading to uneven coating. Therefore, in the process of FIG. 20, in order to prevent such suction of bubbles, the discharge speed is set to the third speed after the discharge at the second discharge speed V ₂ is completed.
Are only adding a small amount of the coating liquid 3 ejected a short time by reducing the discharge velocity V ₃ of the.

The dripping amount of the coating liquid 3 at the _third discharge speed V ₃ is preferably as small as possible. This dripping amount is set to 0.01 to 0.02 ml, for example. In this case, the third discharge speed V
_{When 3} is set to 1 ml / s, the dropping time of the coating liquid 3 at the _third discharge speed V ₃ is 0.01 to
0.02 s, which is very short.

FIG. 21 shows a modification of FIG. In FIG. 21, first, the coating liquid 3 is discharged at the first discharge speed V ₁ while rotating the substrate 1 at the first rotation speed N ₁ . Next, the coating liquid 3 is discharged at the second discharge speed V ₂ while maintaining the rotation speed of the substrate 1 at the first rotation speed N ₁ . Next, the rotation speed of the substrate 1 is decelerated to the second rotation speed N _2, and the discharge speed of the coating liquid ₃ is decreased to the _third discharge speed V ₃ during the deceleration. Then, while the substrate 1 is being rotated at the second rotation speed N ₂ , the discharge at the third discharge speed V ₃ is finished. According to the process of FIG. 21, the discharge state of the coating liquid 3 can be improved similarly to the process of FIG.

Note that the discharge at the third discharge speed V ₃ in FIGS. 20 and 21 may be performed after the discharge at the _second discharge speed V ₂ in any of FIGS. That is, the processes of FIGS. 20 and 21 may be executed in combination with the processes of FIGS.

Further, as in the process of FIG. 20 and FIG. 21, a method for improving the discharge state by discharging a small amount of the coating liquid 3 at a low discharge speed at the end of discharge is not limited to the spin coating method, and is also used in other coating methods. can do. This technique can also be applied when the pre-wet liquid 2 is not used. When the pre-wet liquid 2 is not used, the use amount of the coating liquid 3 is increased as compared with the case where the pre-wet liquid 2 is used, but due to the effect of the discharge speed control of the second embodiment,
The coating film 4 with good in-plane uniformity of film thickness can be formed.

20 and 21, after the application liquid 3 is discharged at the _two discharge speeds V ₁ and V ₂ , the discharge for improving the discharge state is performed. After discharging the coating liquid 3 at a discharge speed that is higher than the level, discharging for improving the discharging state may be performed. In other words, the discharge speed may be changed any number of times before the discharge for improving the discharge state.

Further, a step of changing the rotation speed of the substrate 1 may be added before, during or after the discharge of the coating liquid ₃ at the discharge speed V ₃ .

6 to 21 is only an example of the spin coating method of the second embodiment, and the spin coating method of the second embodiment may be executed by combining the processes of FIG. 6 to FIG. 21, for example. Alternatively, it may be executed in a form different from the processes of FIGS.

In order to perform the coating process while changing the rotation speed of the substrate 1 and the discharge speed of the coating liquid 3 as in the second embodiment, it is desirable to perform precise rotation speed control and discharge control. For example, when a photoresist is used as the coating solution 3, it may be required to set the dripping amount to 0.5 ml or less at present. Therefore, precise control capable of executing the coating process of the second embodiment is desired even under such circumstances.

For example, in the coating process of FIG. 6, it is assumed that the first discharge amount M _{1 is set} to 0.4 ml and the second discharge amount M ₂ is set to 0.1 ml (M ₁ + M ₂ = 0.5 ml). In this case, when the first discharge speed V ₁ is 0.5 ml / s, the time T ₁ is 0.8 s. The second discharge speed V
_{When 2} is 1 ml / s, the time T ₂ is 0.1 s. Here, the second discharge speed V _{2 is set} to 2 m
When it is increased to 1 / s, the time T ₂ is shortened to 0.05 s. Thus, the second discharge speed V ₂
If the value is increased, the time T ₂ needs to be shortened, and more precise control is required.
A countermeasure for this problem will be described later.

2) Specific Example of Spin Coating Method of Second Embodiment FIG. 22 is a table for explaining a specific example of the spin coating method of the second embodiment. FIG. 22 shows an example of a recipe for the spin coating method of the second embodiment. Hereinafter, the case where the above-mentioned spin coater is operated with this recipe will be described. In the experiment relating to this recipe, the coating solution 3 having a viscosity of 1 mPa · s was used.

First, the pre-wet liquid supply unit 11 drops the pre-wet liquid 2 on the central portion of the wafer 1 by the dropping amount M _p (step S1). The dripping amount M _p is, for example, 3 ml.

Then, by rotating the wafer 1 at a rotational speed N _p by a motor 15, extending the pre-wet liquid to the surface of the wafer 1 (step S2). The rotation speed N _p is, for example, 1000 to 4000 rpm, and the rotation time T _p2 is, for example, 0.1 to 3 s (desirably 0.5 s or more).

Next, while the wafer 1 is rotated at the first rotation speed N ₁ by the motor 15, the coating liquid 3 is dropped by the first dropping amount M ₁ onto the center of the wafer 1 by the coating liquid supply unit 12. The coating liquid 3 is spread on the surface of the wafer 1 (step S3).

Here, the first rotation speed N ₁ may be set to a rotation speed at which the first dropping amount M ₁ of the coating liquid 3 does not spread uniformly over the entire wafer 1 due to air resistance. For example, when the diameter of the wafer 1 is 300 mm, the first rotation speed N ₁ is set to 2500 to 4000 rpm. Since the pre-wet liquid 2 dropped before the coating liquid 3 has low viscosity, it is not easily affected by air resistance.
Therefore, even if the coating liquid 3 does not flow on the substrate 1 due to air resistance, the pre-wet liquid 2 can flow on the substrate 1 and reach the outer peripheral portion of the substrate 1. The first rotation speed N
₁ may be lower than 2500 rpm so that the coating liquid 3 is not easily subjected to air resistance.

The first drop amount M ₁ is, for example, about 0.3 ml. In step S3, while discharging the coating liquid 3 in the first discharge speed V _1, the discharge speed V ₁ of the the first 0.2～0.8Ml
Set to / s. As a result, the discharge time at the first discharge speed V ₁ is 0.375 to 1.5.
s. In this case, the rotation time T ₁ is set in accordance with the discharge time, but it is not necessary to completely match the discharge time, and the discharge start and discharge end timings do not match the rotation start and rotation end timings. Also good.

Next, the coating liquid 3 is applied to the central portion of the wafer 1 by the coating liquid supply unit 12 while the wafer 1 is rotated by the motor 15 at a _second rotational speed N ₂ smaller than the first rotational speed N _2. By dropping the amount M ₂ , the coating liquid 3 is further spread on the surface of the wafer 1 (step S4).

The dropping of the first dropping amount M ₁ of the coating liquid 3 and the dropping of the second dropping amount M ₂ of the coating liquid 3 may be performed continuously. Further, the second drop amount M ₂ may be smaller than the first drop amount M ₁ , and is set to about 0.1 ml, for example. In this case, the total dripping amount M ₁ + M ₂ of the coating liquid 3 is 0.4 ml.
It will be about. Further, the second rotation speed N ₂ is set to 2000 to 3000 rpm, for example.
A value smaller than the first rotation speed N ₁ is set.

In step S4, while discharging the coating liquid 3 in the second discharge speed V _2, setting this second discharge speed V ₂ in 1.0~2.5ml / s. As a result, the discharge time by the second discharge speed V ₂ becomes 0.04～0.1S. In this case, the rotation time T ₂ is set according to the discharge time, but it is not necessary to completely match the discharge time, and the discharge start and discharge end timings do not match the rotation start and rotation end timings. Also good.

Next, the wafer 1 is rotated by the motor 15 at the film thickness determination rotation speed N ₄ (step S5).
. Thereby, the film thickness of the coating film 3 coated on the wafer 1 is controlled to a desired value. Rotational speed N
For example, ₄ is 1900 rpm, and the rotation time T ₄ is 15 s, for example.

Thereafter, in this recipe, edge cutting and back surface cleaning of the coating liquid 3 are performed by a thinner. Further, the wafer 1 is automatically conveyed to a hot plate, and the wafer 1 is baked by the hot plate to evaporate the solvent of the coating liquid 3. Further, the baked wafer 1 is cooled. Thus, the coating film 4 is formed from the coating solution 3.

When the coating solution 3 applied in this recipe was observed and its film thickness was measured, coating unevenness was not observed and the in-plane uniformity of the film thickness was also good.

FIG. 23 is a table for explaining another specific example of the spin coating method of the second embodiment. FIG.
3 shows an example of the recipe of the spin coating method of the second embodiment, as in FIG.

First, the prewetting liquid 2 is dropped on the wafer 1 by the dropping amount M _p (step S1). The dripping amount M _p is, for example, 3 ml. Then, the wafer 1 is rotated at a rotational speed N _p, spread the pre-wet liquid to the surface of the wafer 1 (step S2). The rotation speed N _p is, for example, 1000 to 400.
The rotation time T _p2 is, for example, 0.1 to 3 s.

Next, the coating liquid 3 is spread on the surface of the wafer 1 by dropping the coating liquid 3 onto the wafer 1 by the first dropping amount M ₁ while rotating the wafer 1 at the first rotation speed N ₁ (step S1). S3). The first rotation speed N ₁ is, for example, 2500 to 4000 rpm, and the first drop amount M ₁ is, for example, about 0.3 ml. In step S3, while discharging the coating liquid 3 in the first discharge speed V _1, to set the discharge speed V ₁ of the first to 0.2~0.8ml / s.

Next, while rotating the wafer 1 at the first rotation speed N ₂ is less than the second rotational speed N _2, the wafer 1 to the coating liquid 3 by dropwise by a second drop amount M _2, the wafer 1 The coating liquid 3 is further spread on the surface (step S4). The second rotational speed N ₂ is, for example, 2000 to 3000 rpm, and the second dropping amount M ₂ is, for example, about 0.1 ml. In step S4, while discharging the coating liquid 3 in the second discharge speed V _2, the second discharge speed V ₂ 1.0 to 2.5
Set to ml / s.

Then, the wafer 1 is rotated at a rotational speed N ₃ performing a reflow process (step S5). By this reflow process, the film thickness uniformity of the coating liquid 3 applied on the wafer 1 is improved. The rotation speed N ₃ is, for example, 100 rpm, and the rotation time T ₃ is, for example, 1 s.

Next, the wafer 1 is rotated at the film thickness determination rotation speed N ₄ (step S6). Thereby, the film thickness of the coating film 3 coated on the wafer 1 is controlled to a desired value. The rotation speed N ₄ is, for example, 19
The rotation time T ₄ is, for example, 15 s.

Thereafter, in this recipe, edge cutting of the coating liquid 3, back surface cleaning, baking of the wafer 1, and cooling of the wafer 1 are performed. Thus, the coating film 4 is formed from the coating solution 3.

When the coating solution 3 applied in this recipe was observed and its film thickness was measured, coating unevenness was not observed and the in-plane uniformity of the film thickness was also good.

FIG. 24 is a table showing experimental results when the spin coating method of the second embodiment is performed. Specifically, FIG. 24 shows observation results of coating unevenness and measurement results of film thickness uniformity when the coating film 3 is applied with various coating amounts M ₁ + M ₂ by the recipe of FIG. .

According to the results shown in FIG. 24, the film thickness uniformity was good even at M ₁ + M ₂ = 0.30 ml, but coating unevenness occurred at M ₁ + M ₂ = 0.30 ml. From this result, the coating amount M ₁ + M ₂ is 0.32
It was found that when the amount was set to ml or more, the coating film 3 having good film thickness uniformity was obtained while suppressing the occurrence of coating unevenness.

On the other hand, without using the prewetting liquid 2, M ₁ + M ₂ = 0.40 ml is set as shown in FIGS.
When the coating film 3 is applied by the above-described recipe or the other method of the second embodiment, no matter what method is adopted, uneven coating occurs, and there is a place where the coating film 3 is not applied to the outer peripheral portion of the wafer 1. The remaining.

Here, an experimental result in the case where the discharge at the _third discharge speed V ₃ for improving the discharge state is applied to the recipe of FIG. 22 will be described.

After the discharge of the discharge speed V ₂ recipes of the second 22 was subjected to the state observer of the coating solution nozzle 12c, the difference between the first discharge speed V ₁ and the second discharge speed V ₂ As the size increased, a phenomenon was observed in which the coating liquid 3 flows backward while air was sucked into the nozzle 12c at the same time as the end of discharge. When this phenomenon becomes remarkable, bubbles are taken into the pipe, and problems such as poor coating occur.

Therefore, first the recipe of FIG. 22, after discharging the coating liquid 3 in the second discharge speed V _1, V _2, discharging the coating liquid 3 by ejection amount M ₃ in the third discharge velocity V _3. The value of V ₃ was set to a value of V ₁ or more and less than V ₂ . For example, V ₃ is set to 0.25 to 1.0 ml / s, and M ₃ is set to 0.01.
When set to ˜0.02 ml, the discharge state of the nozzle 12c was improved.

The discharge amount of the coating liquid 3 at the _third discharge speed V ₃ is 0.1 ml or less (for example, 0.01
˜0.20 ml) is sufficient, and the discharge time is 0.1 s or less (for example, 0.01 to
0.02s) is often set. Therefore, the coating liquid supply unit 12 of the present embodiment can control the discharge amount of the coating liquid 3 in units of 0.1 ml or less (for example, 0.01 ml unit or less), and discharge the coating liquid 3. Time is a unit of 0.1 s or less (for example, 0.
It is desirable to be able to control in units of 01s or less). Such a configuration can be realized, for example, by reducing the diameter of the nozzle 12c or improving the performance of the discharge control device 12e. Similarly, it is desirable that the rotation time of the motor 15 be controlled in units of 0.1 s or less (for example, units of 0.01 s or less).

In the present embodiment, with such a configuration, the coating liquid 3 is supplied to the first to third discharge speeds V, respectively.
_{The 1st- 3rd} discharge time discharged by _1- V3 shall be 0.1 s or less, and the coating liquid during discharge of the coating liquid ₃ by _{1st- 3rd} discharge speed V1-V3, respectively. The first to third discharge amount of 3 is 0.1
It becomes possible to make it below ml. In the present embodiment, only one of the first to third ejection times may be 0.1 s or less, and two or more may be 0.1 s or less. Similarly, in the present embodiment, only one of the first to third discharge amounts may be 0.1 ml or less, and two or more may be 0.1 ml or less.

Note that such a configuration of the coating liquid supply unit 12 and the motor 15 not only improves the accuracy of ejection at the _third ejection speed V ₃ , but also includes the first and second ejection speeds V ₁ and V ₁ . The accuracy of the switching between ₂ will also be improved.

As described above, in this embodiment, the coating liquid 3 is rotated while the substrate ₁ is rotated at the _first rotation speed N _1.
Is dropped onto the substrate 1 at the first discharge speed V ₁ . Further, in the present embodiment, when the coating liquid 3 is dropped while rotating the substrate 1 at the second rotational speed N ₂ smaller than the rotational speed N ₁ , the coating liquid 3 is made faster than the first discharge speed V _1. discharging the substrate 1 at a faster second discharge speed V _2. Thereby, according to this embodiment, it becomes possible to form the coating film 4 in a wider range, while reducing the dripping amount of the coating liquid 3. Furthermore, according to the present embodiment, the in-plane uniformity of the film thickness of the coating liquid 3 can be further improved as compared with the case of the first embodiment.

Although the first and second embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms. Moreover, various modifications can be obtained by making various omissions, substitutions, and changes to these embodiments without departing from the scope of the invention. These forms and modifications are included in the scope and gist of the invention, and these forms and modifications are included in the claims and the scope equivalent thereto.

For example, according to these embodiments, even when pre-wetting is not performed, the usage amount of the coating liquid 3 can be reduced by changing the discharge speed. In these embodiments,
When the pre-wetting is not performed, the end of the coating liquid 3 may not be raised, or the coating liquid 3 may reach the end of the substrate 1 by discharging the first drop amount M _1. Good.

1: substrate (wafer), 2: pre-wet liquid, 3: coating liquid, 4: coating film,
11: Pre-wet liquid supply part, 12: Coating liquid supply part, 13: Holding part, 14: Rotating shaft,
15: Motor, 16: Vacuum line, 17: Suction source, 18: Control unit

Claims (6)

A pre-wet liquid supply unit for dripping the pre-wet liquid onto the substrate;
A coating solution supply unit for dropping the coating solution on the substrate;
A motor for rotating the substrate;
The pre-wet liquid supply unit, the coating liquid supply unit, and a control unit that controls the operation of the motor,
The controller is
The pre-wet liquid is dropped on the substrate by the pre-wet liquid supply unit, and the substrate is rotated by the motor to spread the pre-wet liquid on the surface of the substrate,
After spreading the pre-wet liquid on the surface of the substrate, the coating liquid is first discharged onto the substrate by the coating liquid supply unit while rotating the substrate at a first rotation speed (rpm) by the motor. By dropping only the first dropping amount at a speed, the coating liquid is spread to a position inside the end of the substrate,
After dripping the coating liquid by the first dripping amount, the substrate is moved to the first by the motor.
The coating liquid is supplied to the substrate by the coating liquid supply unit at a second discharge speed higher than the first discharge speed while rotating at a second rotation speed (rpm) smaller than the second rotation speed. By dripping only the dripping amount, the coating liquid is spread to the end of the substrate or near the end,
After the coating liquid is discharged at the second discharge speed, the coating liquid is supplied by the coating liquid supply unit at a third discharge speed slower than the second discharge speed, and the first drop amount and the first A third drop amount smaller than the sum of the drop amounts of 2 is discharged onto the substrate;
The coating liquid supply unit sets the second discharge time to 0.1 second or less among the first and second discharge times for discharging the coating liquid at the first and second discharge speeds, respectively.
Of the first and second dripping amounts, the coating liquid supply unit has a second dripping amount of 0.1 ml.
Below and then,
After the coating liquid is discharged at the third discharge speed, the substrate is moved to the second position by the motor.
The third rotation number is smaller than the first rotation number and larger than the second rotation number.
Accelerate to the rotation speed (rpm), rotate at the third rotation speed for a predetermined period,
Process of decelerating the substrate from the first rotational speed to the second rotational speed by the motor
And changing the discharge speed from the first discharge speed to the second discharge speed,
The motor completes deceleration of the substrate from the first rotational speed to the second rotational speed.
And changing the discharge speed from the second discharge speed to the third discharge speed ,
Spin coating device. A coating solution supply unit for dropping the coating solution on the substrate;
A motor for rotating the substrate;
A control unit for controlling the operation of the coating liquid supply unit and the motor,
The controller is
While rotating the substrate at a first rotation speed (rpm) by the motor, the coating liquid supply unit drops the coating liquid onto the substrate by a first discharge rate by a first dropping amount,
After dripping the coating liquid by the first dripping amount, the substrate is moved to the first by the motor.
The coating liquid is supplied to the substrate by the coating liquid supply unit at a second discharge speed higher than the first discharge speed while rotating at a second rotation speed (rpm) smaller than the second rotation speed. Drip as much as the drop amount,
After the coating liquid is discharged at the second discharge speed, the coating liquid is supplied by the coating liquid supply unit at a third discharge speed slower than the second discharge speed, and the first drop amount and the first only the third drop amount less than the sum of the second dropping amount discharged to the substrate,
After the coating liquid is discharged at the third discharge speed, the substrate is moved to the second position by the motor.
The third rotation number is smaller than the first rotation number and larger than the second rotation number.
Accelerates to a rotational speed (rpm) and rotates at the third rotational speed for a predetermined period of time ,
Spin coating device. When the coating liquid is dropped while rotating the substrate at the second rotational speed, the coating liquid is ejected at the first ejection speed, and then the ejection speed is set by the coating liquid supply unit. Changing the discharge speed without stopping the discharge from the discharge speed to the second discharge speed;
The spin coater according to claim 2. While the substrate is rotated at the first rotation speed by the motor, the coating liquid is dropped onto the substrate by the first dropping amount by the coating liquid supply unit, thereby being located inside the end portion of the substrate. Spread the coating solution to the position of
After the coating solution is dropped by the first dropping amount, the substrate is moved to the second by the motor.
The coating liquid is spread to the end of the substrate or near the end by dropping the coating liquid onto the substrate by the second dropping amount while rotating at the number of rotations.
The spin coater according to claim 2 or 3. 5. The spin coater according to claim 4, wherein the first number of rotations is a number of rotations at which swell occurs at an end of the coating liquid that has spread to a position inside the end of the substrate. Furthermore, a pre-wet liquid supply unit that drops the pre-wet liquid on the substrate is provided,
The control unit controls operations of the pre-wet liquid supply unit, the coating liquid supply unit, and the motor,
The pre-wet liquid is dropped on the substrate by the pre-wet liquid supply unit, and the substrate is rotated by the motor to spread the pre-wet liquid on the surface of the substrate,
After spreading the pre-wet liquid on the surface of the substrate, the coating liquid is applied to the substrate by the coating liquid supply unit while rotating the substrate at the first rotation speed by the motor.
The first drop amount is dropped at a discharge speed of
The spin coater according to any one of claims 2 to 5.

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