JP2004064071A - Method for manufacturing semiconductor integrated circuit device - Google Patents

Abstract

A photoresist capable of reducing the amount of photoresist used by dropping the photoresist at a high rotation speed and obtaining high-precision in-plane film thickness accuracy in forming a photoresist on a substrate (wafer). Provide coating technology.
Kind Code: A1 A coating apparatus for depositing a photoresist to a predetermined film thickness by dropping a photoresist on a wafer and rotating the wafer, wherein the photoresist is spin-coated on the wafer. While rotating at a rotation speed RH higher than the photoresist film formation rotation speed RL, the photoresist is dropped and spread over the entire surface of the wafer. This is a coating method in which the wafer rotation speed is controlled so that the photoresist is formed at the film formation rotation speed RL at which the film thickness becomes large.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photolithography technique used in a manufacturing process of a semiconductor integrated circuit and the like, and in particular, a photoresist coating method suitable for applying a small amount of a photoresist to a substrate such as a semiconductor wafer, and a semiconductor integration using the same. The present invention relates to a method for manufacturing a circuit device, and a technique effective when applied to a photoresist coating device.
[0002]
[Prior art]
For example, as a technique studied by the inventor, when a photoresist is applied to a wafer, a method called a spin coating method in which a film is formed by rotating a substrate has been put to practical use. This spin coating method is described in, for example, Non-Patent Document 1.
[0003]
In this spin coating method, the wafer is vacuum-adsorbed and held by a spinner capable of rotating the wafer to about 5000 rpm, and the wafer is stopped or rotated at a film formation rotation speed of a predetermined photoresist film thickness formed on the wafer. Then, the photoresist is dropped, and then the rotation speed is increased to the film formation rotation speed, and the photoresist is stretched by continuing the rotation to obtain a predetermined film thickness saturated at the rotation speed.
[0004]
[Non-patent document 1]
Silicon Processing for the VLSI Era, 1986, P430-P432
[0005]
[Problems to be solved by the invention]
However, in the spin coating method as described above, for a large-diameter wafer such as a φ200 wafer having a diameter corresponding to 8 inches, for example, if this film-forming rotation is performed at a high rotation such as about 4000 rpm or more, air may be generated on the outer peripheral portion of the wafer. Turbulence is generated, which causes a problem that film thickness accuracy of coating is deteriorated.
[0006]
For this reason, when the viscosity of the photoresist is reduced and the coating film is formed at a low rotation speed of about 4000 rpm or less, the spreading time of the dropped resist over the entire wafer increases because the resist rotation speed is also reduced. There is a problem that the amount of resist required for film formation increases.
[0007]
Therefore, an object of the present invention is to reduce the amount of photoresist used by dripping photoresist at a high rotation speed, and to obtain a high-precision in-plane film thickness accuracy in forming a photoresist on a substrate. An object of the present invention is to provide a photoresist coating method, a method of manufacturing a semiconductor integrated circuit device using the same, and a photoresist coating apparatus.
[0008]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0009]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
[0010]
That is, the photoresist coating method of the present invention is applied to a coating method in which a photoresist is dropped on a substrate, and the substrate is rotated to form a photoresist coating film to a predetermined thickness. When the photoresist is spin-coated on the substrate, the photoresist is dropped and spread over the entire surface of the substrate while rotating the substrate at a rotation speed higher than the film formation rotation speed of the photoresist. The photoresist film is formed at a film forming rotation speed at which the film thickness is reduced to a predetermined film thickness.
[0011]
In this case, when the photoresist is dropped, the photoresist is dropped while the substrate is accelerated to a rotation speed equal to or higher than the film formation rotation speed. After the substrate is rotated at a rotation speed equal to or higher than the film formation rotation speed, the photoresist is dropped during the deceleration from the rotation speed higher than the film formation rotation speed, and the photoresist is directly reduced to the film formation rotation speed, or Photoresist is dropped onto the rotating substrate as described above, and when the film thickness reaches a predetermined film thickness while rotating at the film forming rotation speed or more, the rotation of the substrate is stopped to obtain a predetermined film thickness. It is.
[0012]
Further, after the photoresist is dropped on the substrate, the number of rotations is reduced and the film is formed at the number of rotations having a predetermined film thickness immediately after the formation of the photoresist coating film is confirmed by the coating confirmation means. It was made.
[0013]
Further, in the method of manufacturing a semiconductor integrated circuit device according to the present invention, the substrate is a semiconductor wafer, and after a coating film of a photoresist is formed on the semiconductor wafer, a photolithography process such as exposure and development is performed. The semiconductor integrated circuit device is formed through the semiconductor integrated circuit manufacturing process described above.
[0014]
Further, the photoresist coating apparatus of the present invention is configured such that the photoresist is dropped at a predetermined timing corresponding to the number of rotations of the substrate, and the substrate is rotated at a predetermined number of rotations corresponding to the dropping of the photoresist. And rotation control means.
[0015]
In this case, a photoresist application confirming means is provided near the outer peripheral portion of the substrate, and after the photoresist is dropped by the dropping control means, the photoresist is rotated by the rotation control means immediately after the application confirming means confirms the photoresist coating film. The film is formed at a rotation speed at which the number is reduced to a predetermined film thickness.
[0016]
(Action)
According to the above-described photoresist coating method, and a method for manufacturing a semiconductor integrated circuit device using the same, and a photoresist coating apparatus, the number of film forming rotations, that is, the rotation, until the photoresist is dropped and spread over the entire surface of the substrate When the resist is dropped and spread over the entire surface of the substrate by performing the film formation at a high rotation speed equal to or higher than the number of rotations saturated to a predetermined film thickness, and dropping to the film formation rotation speed immediately after the completion of the dropping, Is rotated at a high speed, so that a small amount of photoresist can be used to form a coating film of photoresist on the entire surface of the substrate.
[0017]
In addition, when the photoresist spreads over the entire surface of the substrate, the film is decelerated to a film forming rotation speed before reaching a predetermined film thickness. Can be.
[0018]
Furthermore, when the coating film is formed by the film formation rotation speed, the rotation of the substrate is not affected by the turbulence of the air due to the low speed, so that the in-plane film thickness of the photoresist on the substrate is reduced. Deterioration can be prevented.
[0019]
In particular, by shortening the time during which the substrate is rotated at a turbulent flow generation speed that adversely affects the coating film thickness accuracy, that is, a rotation speed higher than the film formation rotation speed, it is possible to further improve the film thickness accuracy. it can.
[0020]
In this case, since the photoresist application confirmation means is provided near the outer peripheral portion of the substrate, the photoresist can be reduced to the film forming rotation speed after confirming that the photoresist has spread on the substrate by the application confirmation means. The film formation can be performed stably with respect to fluctuations in the dropping time, dropping amount, and the like.
[0021]
Thus, when a coating film of a photoresist is formed on a substrate, particularly a semiconductor wafer, the amount of the photoresist used is reduced, and a highly accurate in-plane thickness accuracy of the photoresist at the time of film formation is obtained. be able to.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
(Embodiment 1)
FIG. 1 is a front view showing the periphery of a wafer in a processing section of a photoresist coating apparatus according to the first embodiment of the present invention. FIG. 2 is a time-dependent sequence of the number of rotations of the wafer in the processing section of the photoresist coating apparatus of the present embodiment. FIG.
[0024]
First, the configuration of the processing unit of the photoresist coating apparatus according to the present embodiment will be described with reference to FIG.
[0025]
The photoresist coating apparatus according to the present embodiment is, for example, a coating apparatus that drops a photoresist on a semiconductor wafer and rotates the semiconductor wafer to form a coating film of the photoresist to a predetermined thickness. A coating processing section 1 of the coating apparatus is provided with a spin chuck 3 for rotatably holding a wafer 2 (substrate) at a predetermined number of rotations, and is disposed above the wafer 2, and a photoresist 4 is dropped on the wafer 2. And the like.
[0026]
A spin motor 6 is connected to the spin chuck 3, and the spin motor 6 is connected to a rotation control unit 7 (rotation control means). The rotation control unit 7 drops the photoresist 4 onto the wafer 2. Correspondingly, the spin motor 6 and the wafer 2 held by vacuum suction on the spin chuck 3 connected to the spin motor 6 are controlled to rotate at a predetermined rotation speed.
[0027]
The discharge nozzle 5 is connected to a drop control unit 8 (drop control unit), and the drop control unit 8 controls the photoresist 4 to drop at a predetermined timing in accordance with the rotation speed of the wafer 2. I have.
[0028]
Next, with respect to the operation of the present embodiment, a coating method in the case of actually forming a coating film of the photoresist 4 on the wafer 2 based on the chronological sequence of the number of rotations of the wafer shown in FIG. 2 will be described.
[0029]
FIG. 2 shows the spinner rotation speed [rpm] with respect to the elapsed time [sec], and the scales of the elapsed time and the spinner rotation speed are not limited to these. For example, a case of a φ200 wafer is taken as an example. Is shown. The spinner is a general term including the spin chuck 3, the spin motor 6, and the like.
[0030]
In each of the rotation speeds shown here, the rotation speed at which the photoresist 4 is easily spread by a small amount is set as the rotation speed at which the resist is dropped, the rotation speed at which the turbulent flow is generated is the rotation speed at which air turbulence occurs, and the film formation rotation speed is a predetermined rotation speed The number of rotations saturated with the film thickness is set.
[0031]
First, the wafer 2 sucked and held by the spin chuck 3 is rotated by the spin motor 6 at a resist drop rotation speed RH, for example, about 7000 rpm. A time of, for example, about 1.0 sec is required before the resist drop rotation speed RH. The photoresist 4 is dropped on the rotated wafer 2 only for a resist dropping time Ta, for example, about 0.5 sec.
[0032]
After completion of the dropping of the photoresist 4, the wafer 2 is maintained at the rotation speed of the resist drop rotation speed RH for a time Tb until the photoresist 4 spreads over the entire surface of the wafer 2, for example, about 0.5 sec. Thereafter, the film is decelerated to a turbulent flow generation rotational speed RR, for example, about 4,000 rpm or less, for example, about 3000 rpm, and rotated until the film thickness does not change at that rotational speed to form a film. For example, a time of about 0.4 sec is required until the film formation rotation speed RL due to the deceleration.
[0033]
In this aging sequence, after the time Tb until the photoresist 4 spreads over the entire surface of the wafer 2 ends, and if the time to decelerate to the turbulent flow rotation speed RR or less is Tc, the time until the deceleration is reached. It is effective to shorten the time Tc as much as possible to obtain the accuracy of the film thickness. In this case, the time Tc is, for example, about 0.3 sec.
[0034]
Therefore, according to the coating method in the photoresist coating apparatus of the present embodiment, when the photoresist 4 is dropped, and when the photoresist 4 is spread over the entire surface of the wafer 2, the wafer 2 is rotated at a high speed. A coating film can be formed on the entire surface of the wafer 2 with a small amount of the photoresist 4.
[0035]
Although the photoresist 4 spreads over the entire surface of the wafer 2, the photoresist 4 is reduced to a film forming rotation number RL before reaching a predetermined film thickness. it can.
[0036]
Furthermore, since the rotation of the wafer 2 is slow during the film formation, the in-plane film thickness is prevented from deteriorating without being affected by the turbulence.
[0037]
(Embodiment 2)
FIG. 3 is a timing chart showing a chronological sequence of the number of rotations of the wafer in the processing unit of the photoresist coating apparatus according to the second embodiment of the present invention.
[0038]
The photoresist coating apparatus of the present embodiment drops a photoresist 4 on a wafer 2 (substrate) and rotates the wafer 2 to form a coating film of the photoresist 4 in a predetermined manner as in the first embodiment. A coating apparatus for forming a film having a film thickness is different from that of the first embodiment in that the photoresist 4 is dropped during acceleration to a rotation speed RH equal to or higher than a turbulence generation rotation speed RR.
[0039]
That is, as shown in FIG. 3, while the wafer 2 is being accelerated to a rotational speed RH of about 7000 rpm, the photoresist 4 is started to be dropped at a rotational speed of about 3000 rpm, for example, and reaches a resist dropping time Ta, for example, a rotational speed RH. The photoresist 4 is dropped only for about 0.5 sec.
[0040]
Immediately after the completion of the dropping of the photoresist 4, the film is decelerated to a film formation rotation speed RL of about 3000 rpm, and rotated until the film thickness does not change at the rotation speed. For example, a time of about 0.4 sec is required until the film formation rotation speed RL due to the deceleration.
[0041]
In this chronological sequence, assuming that the time during which the photoresist 4 starts dropping and the wafer 2 is rotated at a rotational speed equal to or higher than the turbulent flow generation rotational speed RR is Tr, it is necessary to shorten this time Tr as much as possible. This is effective in obtaining thickness accuracy, and is, for example, about 0.75 sec here.
[0042]
Therefore, according to the coating method in the photoresist coating apparatus of the present embodiment, as in the first embodiment, a coating film can be formed on the entire surface of the wafer 2 with a small amount of the photoresist 4, and the photoresist 4 can be rotated at a high speed. A predetermined thick film is obtained while dropping, and the effect of preventing the deterioration of the in-plane film thickness without being affected by the turbulence is obtained. The film thickness accuracy can be further improved by shortening the time Tr during which the wafer 2 is rotated at RR or more.
[0043]
(Embodiment 3)
FIG. 4 is a timing chart showing a temporal sequence of the number of rotations of the wafer in the processing unit of the photoresist coating apparatus according to the third embodiment of the present invention.
[0044]
The photoresist coating apparatus of the present embodiment drops a photoresist 4 on a wafer 2 (substrate) as in the first and second embodiments and rotates the wafer 2 to form a coating film of the photoresist 4. This coating method is a coating apparatus for forming a film having a predetermined thickness. The difference between this coating method and the first and second embodiments is that the photoresist 4 is dropped during the deceleration from a rotation speed RH equal to or higher than the turbulence generation rotation speed RR. It is a point to do.
[0045]
That is, as shown in FIG. 4, after rotating the wafer 2 at a rotation speed RH of about 7000 rpm, the photoresist 4 is started to be dropped from the start of the deceleration from the rotation speed RH, and the resist dropping time Ta, for example, the film formation rotation time The photoresist 4 is dropped only for about 0.5 sec, which is about 3000 rpm, which is several RL. The film is rotated by this film formation rotation number RL until the film thickness no longer changes.
[0046]
In this chronological sequence, assuming that the time during which the photoresist 4 starts dropping and the wafer 2 is rotated at a rotational speed equal to or higher than the turbulent flow generation rotational speed RR is Tr, it is necessary to shorten this time Tr as much as possible. This is effective in obtaining thickness accuracy, and is, for example, about 0.4 sec here.
[0047]
Therefore, according to the coating method in the photoresist coating apparatus of the present embodiment, a coating film can be formed on the entire surface of the wafer 2 with a small amount of the photoresist 4 in the same manner as in the first and second embodiments. A predetermined thick film can be obtained while the resist 4 is dropped, and the effect of preventing the in-plane film thickness from being deteriorated without being affected by turbulence can be obtained. Therefore, although the amount of the photoresist 4 dropped slightly increases from that in the first embodiment, the time Tr during which the wafer 2 is rotated at a turbulent flow rotation speed RR or more that adversely affects the coating film thickness accuracy is set to the above-described value. Since the length can be further reduced as compared with the second embodiment, the film thickness accuracy can be further improved.
[0048]
(Embodiment 4)
FIG. 5 is a timing chart showing a temporal sequence of the number of rotations of the wafer in the processing unit of the photoresist coating apparatus according to the fourth embodiment of the present invention.
[0049]
The photoresist coating apparatus according to the present embodiment drops a photoresist 4 on a wafer 2 (substrate) as in the first to third embodiments, and rotates the wafer 2 to form a coating film using the photoresist 4. A coating apparatus for forming a film having a predetermined film thickness is different from the first to third embodiments in this coating method. The difference is that the photoresist 4 is rotated while rotating the wafer 2 at a rotation speed RH equal to or higher than the film formation rotation speed RL. Is dropped, and the rotation is stopped at a time Tx at which a predetermined film thickness is obtained.
[0050]
In other words, as shown in FIG. 5, while the wafer 2 is being rotated at a rotational speed RH of about 7000 rpm, the photoresist is dropped only for a period of time from the time when the rotational speed RH is reached to the resist dropping time Ta, for example, about 0.5 sec. 4 is added dropwise. After that, at this rotation speed RH, the rotation of the wafer 2 is stopped after a time Tx, for example, about 1.5 sec, at which a predetermined film thickness is obtained, to form a film.
[0051]
Therefore, according to the coating method in the photoresist coating apparatus of the present embodiment, since the rotation of the wafer 2 is not slow at the time of film formation as in the first to third embodiments, the in-plane film thickness due to the influence of turbulence is formed. Although it is not expected to prevent the deterioration of the film, the amount of resist to be used can be reduced to form a coating film on the entire surface of the wafer 2 with a small amount of the photoresist 4, and a predetermined thick film is obtained while the photoresist 4 is dropped at high speed rotation. be able to.
[0052]
(Embodiment 5)
FIG. 6 is a front view showing the periphery of the wafer in the processing section of the photoresist coating apparatus according to the fifth embodiment of the present invention.
[0053]
The photoresist coating apparatus according to the present embodiment drops a photoresist 4 on a wafer 2 (substrate) in the same manner as in the first to fourth embodiments, and rotates the wafer 2 to form a coating film using the photoresist 4. The coating method is a coating apparatus for forming a film having a predetermined thickness. The difference between this coating method and the first to fourth embodiments is that a sensor 9 (coating confirmation means) for confirming the formation of a coating film near the outer peripheral portion of the wafer 2 is used. ) Is provided.
[0054]
That is, as shown in FIG. 6, a sensor 9 is provided above the outer peripheral portion of the wafer 2 in the coating processing section 1a of the photoresist coating apparatus according to the present embodiment. Is detected, the rotation of the wafer 2 is decelerated to the film forming rotation number RL by this detection signal, and the film is rotated by this rotation number until the film thickness does not change.
[0055]
Therefore, according to the coating method in the photoresist coating apparatus of the present embodiment, a coating film can be formed on the entire surface of the wafer 2 with a small amount of the photoresist 4 as in the first to fourth embodiments. A predetermined thick film can be obtained while dropping the resist 4, and the effect of preventing the deterioration of the in-plane film thickness without being affected by turbulence can be obtained. The above effect can be stably obtained even by the fluctuation of the turbulent flow, and the time Tr during which the rotational speed is always higher than the turbulent flow generation rotational speed RR can be minimized.
[0056]
As described above, the invention made by the inventor has been specifically described based on Embodiments 1 to 5. However, the present invention is not limited to the above embodiment, and can be variously modified without departing from the gist thereof. Needless to say,
[0057]
For example, the photoresist coating apparatus of the above-described embodiment has been described as an example in which the photoresist coating apparatus is applied to a φ200 wafer corresponding to 8 inches, but the present invention is not limited to the above-described embodiment. The present invention can be widely applied to an inch-adaptive φ150 wafer and the like, and a wafer having a diameter of 200 mm or more due to an increase in diameter in the future.
[0058]
In this case, the number of rotations of the resist is not limited to the case where the number of rotations of resist dropping RH is set to 7000 rpm, the number of rotations for generating turbulence RR is set to 4000 rpm, and the number of rotations of film formation RL is set to 3000 rpm. It is needless to say that the modification of is possible.
[0059]
【The invention's effect】
The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.
(1). While rotating the substrate at a rotation speed higher than the photoresist film formation rotation speed, the photoresist is dropped and spread over the entire surface of the substrate, and then the substrate rotation speed is reduced to a predetermined film thickness rotation speed. By forming a photoresist film, the substrate can be rotated at a high speed when the photoresist is dropped and spread over the entire surface of the substrate, so that it is possible to form a coating film using the photoresist over the entire surface of the substrate with a small amount of photoresist. Become.
(2). When the photoresist spreads over the entire surface of the substrate, the film can be decelerated to the film forming rotation speed before reaching the predetermined film thickness, so that the photoresist is dropped at a high speed and a predetermined thick film is obtained at the film forming rotation speed. It becomes possible.
(3). Since the rotation of the substrate can be slowed during the deposition of the coating film by the number of deposition rotations, the in-plane film thickness of the photoresist on the substrate can be reduced without being affected by the turbulence of air. Deterioration can be prevented.
(4). Since the time during which the substrate is rotated at a rotation speed higher than the film formation rotation speed which adversely affects the coating film thickness accuracy can be shortened, the film thickness accuracy can be further improved.
(5). By providing the photoresist application confirmation means in the vicinity of the outer periphery of the substrate, it is possible to reduce the number of rotations of the photoresist after confirming that the photoresist has spread on the substrate by the application confirmation means. It is possible to form a film stably with respect to fluctuations such as a dropping time and a dropping amount.
(6). In the application of photoresist on semiconductor wafers, mask substrates, liquid crystal display device substrates, etc., it is possible to reduce the amount of photoresist used by dripping photoresist at high rotation and to obtain highly accurate in-plane film thickness accuracy. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a front view showing a periphery of a wafer in a processing unit of a photoresist coating apparatus according to a first embodiment of the present invention.
FIG. 2 is a timing chart showing a chronological sequence of the number of rotations of a wafer in a processing unit of the photoresist coating apparatus according to the first embodiment;
FIG. 3 is a timing chart showing a time-dependent sequence of the number of rotations of a wafer in a processing unit of the photoresist coating apparatus according to the second embodiment of the present invention;
FIG. 4 is a timing chart showing a chronological sequence of the number of rotations of a wafer in a processing unit of a photoresist coating apparatus according to a third embodiment of the present invention;
FIG. 5 is a timing chart showing a time-dependent sequence of a wafer rotation speed in a processing unit of a photoresist coating apparatus according to a fourth embodiment of the present invention.
FIG. 6 is a front view showing a periphery of a wafer in a processing section of a photoresist coating apparatus according to a fifth embodiment of the present invention.
[Explanation of symbols]
1, 1a Coating section 2 Wafer (substrate)
Reference Signs List 3 spin chuck 4 photoresist 5 discharge nozzle 6 spin motor 7 rotation control unit (rotation control means)
8 Drop control unit (drop control means)
9 sensors (application confirmation means)

Claims (3)

A method for manufacturing a semiconductor integrated circuit device, in which a photoresist is applied by rotating a substrate to form a film having a predetermined thickness, wherein the photoresist is spin-coated on the substrate. The resist is rotated at a rotation speed equal to or higher than the film formation rotation speed, and the photoresist is dropped on the substrate rotating at the film formation rotation speed or more, and the entire surface of the surface of the substrate on which the photoresist is dropped is rotated. After the photoresist is spread, the rotation of the substrate is stopped when the film thickness reaches a predetermined film thickness while rotating at the film formation rotation speed or more to obtain a predetermined film thickness. A method for manufacturing a circuit device. 2. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the spread of the photoresist on the surface of the substrate is detected by a sensor provided near an outer peripheral portion of the substrate, and the detection signal is used. A method of manufacturing a semiconductor integrated circuit device, wherein the rotation of the substrate is stopped. 3. The method for manufacturing a semiconductor integrated circuit device according to claim 1, wherein the substrate is a semiconductor wafer, and after performing a coating film of the photoresist on the semiconductor wafer, performing exposure and development. A method for manufacturing a semiconductor integrated circuit device.

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