JP3501255B2 - Spin coating method and spin coating device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coating method and a spin coating apparatus suitable for coating a coating liquid such as a photoresist on a semiconductor wafer or a glass substrate for a liquid crystal display.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor IC, a spin coating method is generally used to uniformly apply a photoresist to a semiconductor wafer. In this spin coating method, the semiconductor wafer onto which the photoresist solution is dropped is rotated at 1000 rpm to 2000 rpm. A coating liquid such as a photoresist liquid supplied onto a substrate such as a semiconductor wafer is spread on the surface of the substrate by a centrifugal force generated by the rotation of the substrate, whereby the coating liquid is applied to the surface of the substrate almost uniformly. .

[0003]

However, in the conventional spin coating method as described above, if the amount of the coating liquid containing the volatile organic solvent supplied to the substrate surface is not sufficient, the coating liquid will be deposited on the substrate. When spread, it was thought that the viscosity of the coating liquid increased due to the evaporation of the organic solvent, resulting in uneven coating. Therefore, in order to apply the photoresist liquid, which is the coating liquid, to the surface of the semiconductor wafer, which is the substrate surface, without causing uneven coating, the amount of the coating liquid supplied to the surface of the substrate is more than about 95%, and the substrate is rotated. An extremely large amount of excess coating liquid is supplied onto the substrate so that it is scattered by the centrifugal force from the outer edge of the substrate. Therefore, from the viewpoint of resource saving, there has been a demand for a technique capable of reducing the useless supply amount of the coating liquid.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention rotates a substrate to which a coating liquid is supplied at a high speed which has not been considered in the conventional spin coating method, and Based on the basic concept of effectively coating the surface of a substrate with a small amount of coating liquid without dispersing a large amount of excess coating liquid from the outer periphery of the substrate, the following configuration is adopted.

<Structure> The present invention is a spin coating method in which a substrate is rotated at a high-speed rotation of 4000 rpm or more in order to spread the coating liquid supplied onto the substrate over the entire surface of the substrate by a centrifugal force accompanying the rotation of the substrate. In order to suppress volatilization of the coating liquid supplied onto the substrate, the substrate is rotated at a high speed with the coating liquid covered with the solvent of the coating liquid.

In addition, a spin coater according to the present invention comprises a chuck that is rotated while holding a semiconductor wafer on which a mark indicating the orientation of the substrate is formed, and a coating liquid on the surface of the semiconductor wafer on the chuck. In the spin coating apparatus for a wafer, the adjusting means includes a coating liquid supplying means for supplying the chuck and an adjusting means for aligning a total center of gravity of the semiconductor wafer and the chuck with a rotation center axis line of the chuck. The added counterweight, a device for detecting the position of the counterweight on the chuck, and the semiconductor wafer so that the mark portion of the semiconductor wafer is located on the same side as the counterweight when viewed from the rotation axis. Wafer for disposing the semiconductor wafer on the chuck by aligning the center of the chuck with the rotation axis of the chuck. And a handling device.

<Operations and Effects> In the spin coating method according to the present invention, the coating liquid is used as the solvent.
Since the substrate is rotated at a high speed in a state of being covered with, the action of a strong centrifugal force generated by this high speed causes the coating liquid to instantly spread toward the outer edge of the substrate almost uniformly without causing strong unevenness. As a result, it is possible to increase the strength of this coating liquid by supplying an extremely small amount of coating liquid as compared with the conventional one, without supplying a large amount of coating liquid to the extent that the conventional large amount of excess coating liquid is diffused from the outer edge of the substrate. It can be spread over the entire surface of the substrate without causing unevenness.

Further, a semiconductor wafer, which is one of the substrates, has a circular outer shape as a whole, but the arc portion of the outer edge is cut out along, for example, a straight chord as a mark portion for clearly indicating the crystal orientation. Has been. Therefore, even if the center of gravity of the chuck rotated while the semiconductor wafer is held and the center axis of rotation of the chuck match, if the center of the semiconductor wafer does not match the center of gravity of the semiconductor wafer, the center of the semiconductor wafer is chucked. Even if the semiconductor wafer and the chuck holding the semiconductor wafer are arranged so as to coincide with the rotation axis of the chuck, the total center of gravity of the semiconductor wafer and the chuck holding the semiconductor wafer deviates from the rotation center axis of the chuck. The adjusting means of the spin coater according to the present invention covers the chuck.
By adding an unweight, and arranging the semiconductor wafer so that its center coincides with the rotation center of the chuck,
Even if the chuck is rotated at a high speed of 4000 rpm or more, it ensures stable rotation without shaking of the semiconductor wafer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. <Specific Example> FIG. 1 is a graph showing the relationship between the number of revolutions of the substrate according to the present invention and the necessary minimum supply amount of the coating liquid that does not cause strong unevenness that substantially affects,
Prior to the description along this graph, the spin coater shown in FIG. 2 will be described.

FIG. 2 is a schematic diagram schematically showing a spin coater for semiconductor wafers suitable for carrying out the spin coat method of the present invention. The spin coater 10 includes, for example, a rotating shaft 11 driven at a high speed of 4000 rpm or more.
And a chuck 13 provided with a circular table 12 which is integrally rotated with the rotating shaft 11, and a semiconductor wafer 14 arranged at a predetermined location on the table 12 of the chuck 13, and spin coated. A wafer handling device 15 for removing the processed semiconductor wafer 14 from the table 12 of the chuck 13, and a conventionally well-known coating liquid as a coating liquid supply means for dropping the resist liquid on the surface of the semiconductor wafer 14 on the table 12. And a supply nozzle 16.

The chuck 13 is provided with, for example, a conventionally well-known vacuum suction means (not shown) for holding the semiconductor wafer 14 on the table 12. The center of gravity of the chuck 13 has a rotation axis. It is set on the rotation axis line 11a of the axis 11.

FIG. 3 is a plan view of the semiconductor wafer 14. The semiconductor wafer 14 has a circular outer shape as a whole, but the arc portion of the outer edge is cut out along a straight chord as a mark portion 17 for clearly indicating the crystal orientation. Therefore, although the center position of the semiconductor wafer 14 indicated by the reference numeral 18 is located at the intersection of the two diameter lines of the circular outer shape of the semiconductor wafer 14, the center of gravity position 19 of the semiconductor wafer 14 is located.
Does not coincide with the center position 18 and is biased to the side opposite to the side where the mark portion 17 is provided with respect to the center position 18.

Therefore, the semiconductor wafer 14 is moved by the wafer handling device 15 so that the center position 18 of the semiconductor wafer 14 is the rotation axis 1.
When the chuck 13 holding the semiconductor wafer 14 is placed on the table 12 so as to coincide with 1a, the total center of gravity of the chuck 13 deviates from the rotation axis 11a. This deviation may adversely affect the high speed rotation of 4000 rpm or more as in the present invention.

Therefore, as shown in FIG. 2, adjusting means 20 is provided for correcting the deviation of the total center of gravity position in relation to the wafer handling device 15 so that the total center of gravity position coincides with the rotation axis 11a. Has been. This adjusting means 20
In the example shown in FIG. 2, is a counterweight 21 fixed to one side of the table 12 for compensating for the weight of the defect due to the mark portion 17 of the semiconductor wafer 14, and a position for detecting the position of the counterweight 21. And a detector 22 such as an infrared sensor or a reflection sensor.

The wafer handling device 15 is the semiconductor wafer 1
4 is placed on the table 12, the position of the counterweight 21 is detected based on the information from the detector 22,
As shown in FIG. 4, the semiconductor wafer 14 is placed on the chuck 13 in a posture in which the center position 18 of the semiconductor wafer 14 coincides with the rotation axis 11 a and the mark portion 17 is located on the counterweight 21 side.

By the compensating action of the counterweight 21,
Even if the center of gravity position 19 of the semiconductor wafer 14 deviates from the rotation axis 11a, the total center of gravity position of the semiconductor wafer 14 and the chuck 13 is adjusted on the rotation axis 11a. Accordingly, the table 12 is rotated at a high speed exceeding 4000 rpm, and even if the semiconductor wafer 14 is rotated at a high speed integrally with the rotation of the table 12, the semiconductor wafer 14 is rotated in a stable posture without causing shake. To be done.

In the dynamic dispense method, the semiconductor wafer 14 that rotates integrally with the table 12 is provided.
The resist solution is dripped from the coating solution supply nozzle 16 onto the surface of the coating liquid in a high-speed rotation state without stopping the rotation. The resist liquid dropped from the coating liquid supply nozzle 16 onto the surface of the semiconductor wafer 14 is instantaneously driven by the strong centrifugal force generated by the high speed rotation of the semiconductor wafer 14.
4 extends radially outward and expands.

FIG. 5 is a graph showing the experimental results for obtaining the relationship between the rotation speed of the semiconductor wafer 14 when the resist droplet is dropped and the spread diameter of the dropped resist solution. The X-axis shows the rotation speed (rpm) when the resist solution is supplied, and Y
The axis indicates the spread diameter (mm) of the resist solution at that time. A 6-inch (about 15 cm) semiconductor wafer is used as the sample substrate, and the resist solution has a viscosity of 10
Three types of resist solutions of cp, 100 cp and 180 cp were used.

There is a slight difference in the supplied amount of the resist solution dropped according to the respective viscosities, and the lowest viscosity is 10
0.34 g of the resist liquid of cp, 0.3 g of the resist liquid of 100 cp, and 0.35 g of the resist liquid of 180 cp having the highest viscosity were supplied. The characteristic lines for the resist solutions of various viscosities are symbol A,
It is shown by B and C. As is clear from the comparison of the characteristic lines A, B, and C having different viscosities, the spread diameter of the resist solution increases in accordance with the increase in the rotation of the resist solution when dropped. If the rotation speed is the same,
The spread diameter increases as the viscosity of the resist solution decreases.

In FIG. 1, the resist solution having the viscosity of 10 cp shown in FIG. 5 is used, and the rotation speed of the 6-inch semiconductor wafer 14 at the time of dropping the resist solution and the entire area of the semiconductor wafer 14 are covered by the dropping. 6 is a graph showing an experimental result for obtaining a relationship with a required minimum supply amount of a resist solution, that is, a required minimum dropping amount.

As can be seen from the graph of FIG. 1, at a relatively low rotation speed of less than 2000 rpm as in the conventional case,
It is necessary to drop the resist solution in excess of 2 cc. In addition, about 95% of the supplied 2 cc of resist liquid is 1.9 cc, which is a large amount of resist liquid.
Since it does not adhere to the surface of the semiconductor wafer and scatters outward from the outer edge of the rotating semiconductor wafer 14, it is wasted.

On the other hand, according to the method of the present invention, for example, 4
At high speed of 000 rpm, half the conventional value of 1 cc
By dropping the resist solution, the resist solution can cover the entire surface of the semiconductor wafer 14. As a result, the resist solution can be applied without causing strong unevenness, and the amount of the resist solution diffused from the edge of the semiconductor wafer 14 is a small amount less than 1 cc.

At a rotation speed of 6000 rpm, a resist supply amount of about 0.5 cc is sufficient, and the excess amount diffused from the edge of the semiconductor wafer 14 is 80% of the supply amount.
Is only 0.4 cc. Furthermore, when the rotation speed under the resist droplet reaches 7,000 rpm, about 0.3
The resist supply amount of cc is sufficient, and the amount of resist diffused as an excess amount is as small as 0.2 cc, which is about 66% of the supply amount.

With respect to the increase in the rotation speed, FIG.
In the high-speed range over 7,000 rpm, which is indicated by the broken line of the characteristic curve of Fig. 1, by achieving higher rotation speed, it is possible to further reduce the minimum required amount of resist drop and further reduce the excess amount of radiation. It can be estimated that

Although the example of applying the present invention to the dynamic dispensing method has been described above, the present invention can be applied to the static dispensing method. FIG. 6 shows the relationship between the acceleration of the semiconductor wafer and the spread diameter of the resist solution at that time in the so-called static dispense method in which the resist solution is dropped while the semiconductor wafer is stopped and then the semiconductor wafer is rapidly rotated. It is a graph which shows the obtained experimental result.

In the experiment of FIG. 6, when the 6-inch semiconductor wafer 14 is in a stopped state, a viscosity of 180.
35 g of resist solution was supplied to the semiconductor wafer 14.
The X-axis and the Y-axis of the graph of FIG. 6 are the rotational acceleration (rpm / rpm) given to the semiconductor wafer 14 after the resist solution is supplied.
s) and the spread diameter (mm) of the resist solution.

The characteristic lines D, E, F, G and H show the reached rotational speeds of 2000 after the resist solution is supplied.
rpm, 4000 rpm, 5000 rpm, 7000r
The characteristics in each example of pm and 8000 rpm are shown.
As is clear from the characteristic lines D to H, the spread diameter of the resist solution increases as the reaching rotational speed increases. Also,
The rotational acceleration that gives the maximum value of the spread diameter of the resist solution is approximately 20000 rpm / s. Therefore, 180
For a resist solution having a high viscosity such as cp, by appropriately selecting the duration of this speed with the rotational acceleration showing the maximum resist solution spread diameter, as in the dynamic dispensing system speed, the application of the resist without waste is performed. Is possible.

In the spin coating method by high-speed rotation of the present invention, in comparison with the dynamic dispense method and the static dispense method, it was possible to confirm a more distinct and remarkable resource saving effect in the latter method.

The spread diameter of the resist solution by the spin coating method can be adjusted by adjusting the viscosity of the resist solution. However, when the viscosity is relatively high, the evaporation of the organic solvent of the resist solution is accelerated during high speed rotation. , The resist solution may not spread sufficiently. When such a high-viscosity resist solution is used, in order to suppress the volatilization of the organic solvent, the organic solvent of the resist solution is continuously supplied so as to cover the high-viscosity resist solution supplied on the semiconductor wafer 14. The semiconductor wafer 14 can be rotated at a high speed in this state.

In the spin coater 10 shown in FIG. 7, the highly viscous resist liquid 23 supplied onto the semiconductor wafer 14 is used.
The same organic solvent 24 used for the resist solution 23 is continuously supplied from a solvent supply nozzle 25 so as to cover the resist solution 23. The supply of the solvent 24 is continued until the resist liquid 23 is almost spread over the surface of the semiconductor wafer 14 by the high speed rotation of the semiconductor wafer 14. This solvent 24 is
The volatilization action of the resist liquid 23 thereunder is suppressed. Therefore, it is possible to apply the highly viscous resist solution almost uniformly by the high speed rotation of the semiconductor wafer 14.

The highly viscous resist solution 2 is applied to the semiconductor wafer 14.
3 is supplied, the resist solution 23 is temporarily replaced with the solvent 24 instead of continuously supplying the solvent 24.
The effect of suppressing volatilization of the resist liquid 23 can be expected also by covering with.

Although not shown, as a means for suppressing volatilization of the resist solution supplied to the semiconductor wafer 14, the resist solution supplied on the semiconductor wafer 14 is rotated at a high speed in a predetermined pressurized atmosphere. can do. In order to realize this pressurized atmosphere, the entire spin coater 10 can be placed in the pressurized chamber. Due to the formation of this pressure chamber, the table 12
Although not shown, the outer cup member and the top cup member, which are well known in the art, which are arranged to cover the outer periphery of the above, can be used. Further, it is preferable to keep the inside of the pressurizing chamber in an atmosphere of an organic solvent of the resist solution, and it is possible to suppress the volatilization of the resist solution, whereby the resist solution is applied to the semiconductor wafer 14 more evenly and satisfactorily be able to.

Although the adjusting means 20 including the counterweight 21 and the detector 22 is described in the examples shown in FIGS. 2 and 4, the wafer handling apparatus 15 itself is provided without the counterweight 21 and the detector 22.
The position 19 of the center of gravity of the semiconductor wafer 14 shown in FIG.
Can be placed on the table 12.

By arranging the position 19 of the center of gravity of the semiconductor wafer 14 so as to coincide with the rotation axis 11a by the wafer handling device 15, the semiconductor wafer 14 can be stably and extremely stable without using the counter weight 21 and the detector 22 described above. Good high speed rotation can be realized.

The spin coating method according to the present invention is not limited to the application of the photoresist solution to the above-mentioned semiconductor wafer, but it is possible to apply the coating solution to various substrates such as the application of the photoresist solution to the glass substrate for liquid crystal display. It can be applied to coating.

[0036]

According to the spin coating method of the present invention,
Due to the action of the strong centrifugal force generated by the high speed rotation, a small amount of coating liquid can be instantly and almost evenly spread toward the outer edge of the substrate without causing strong unevenness. It is possible to prevent this, and by supplying an extremely small amount of coating liquid compared to the conventional one, this coating liquid can be spread over the entire area of the substrate surface, and this does not cause significant unevenness that is a substantial problem and wastes. It is possible to efficiently apply the coating liquid with a small amount.

Further, according to the spin coater of the present invention, the adjusting means causes the total center of gravity of the semiconductor wafer and the chuck holding the semiconductor wafer to coincide with the center of rotation of the chuck, so that the chuck has a high speed of 4000 rpm or more. Even when the chuck is rotated at a high speed, the semiconductor wafer can be stably rotated without blurring, so that the method of the present invention can be preferably carried out. By making it possible, it is possible to further reduce the coating liquid.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a minimum required amount of resist droplets and a rotation speed of a semiconductor wafer in a spin coating method according to the present invention.

FIG. 2 is a schematic view schematically showing a spin coater according to the present invention.

FIG. 3 is a plan view of a semiconductor wafer according to the present invention.

FIG. 4 is a perspective view showing a mounting posture of a semiconductor wafer on a chuck according to the present invention.

FIG. 5 is a graph showing the relationship between the number of rotations and the spread diameter of the resist solution in the spin coating method according to the present invention.

FIG. 6 is a graph showing the relationship between the rotational acceleration and the spread diameter of the resist solution in the spin coating method according to the present invention.

FIG. 7 is a schematic view schematically showing another example of the spin coater according to the present invention.

[Explanation of symbols]

10 Spin coater 11 rotation axis 11a Rotation axis 12 tables 13 chuck 14 (Substrate) Semiconductor wafer 15 Wafer handling equipment 16 Coating liquid supply nozzle 17 Mark part 18 Center position 19 Center of gravity position 20 Adjustment means 21 counterweight 22 detector 23 (Coating liquid) Resist liquid 24 solvent 25 Solvent supply nozzle

Continuation of the front page (51) Int.Cl. ⁷ identification code FI H01L 21/30 564C (56) Reference JP-A-4-98823 (JP, A) JP-A-7-328517 (JP, A) JP-A 3-169006 (JP, A) JP-A-6-155213 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/16 502

Claims (2)

(57) [Claims] 1. A spin coating method in which a substrate is rotated at a high speed of 4000 rpm or more in order to spread the coating liquid supplied onto the substrate over the entire surface of the substrate by a centrifugal force accompanying the rotation of the substrate, A spin coating method comprising rotating the substrate at a high speed in a state where the coating liquid is covered with a solvent of the coating liquid in order to suppress volatilization of the coating liquid supplied onto the substrate. 2. A chuck that is rotated while holding a semiconductor wafer on which a mark indicating the orientation of the substrate is formed, a coating liquid supply unit that supplies a coating liquid to the surface of the semiconductor wafer on the chuck, In a spin coating apparatus for a wafer, including an adjusting means for aligning a total center of gravity of the semiconductor wafer and the chuck with a rotation center axis line of the chuck, the adjusting means includes a counter weight added to the chuck and the chuck. An apparatus for detecting the position of the counterweight, and a center of the semiconductor wafer and a rotation axis of the chuck are set so that the mark portion of the semiconductor wafer is located on the same side as the counterweight when viewed from the rotation axis. And a wafer handling device that aligns the semiconductor wafer on the chuck. Spin coat device for air conditioning.