KR0175071B1 - Coating apparatus and method - Google Patents

Abstract

The coating apparatus includes a chuck for sucking a semiconductor wafer, a resist liquid supply system for supplying a resist liquid to the semiconductor wafer, a motor for rotating the semiconductor wafer to spread the resist liquid supplied to the semiconductor wafer to the entire surface of the semiconductor wafer, A semiconductor wafer is placed on it and provided with a plate for forming a temperature distribution thereon.

Description

Application method

1 is a diagram showing a relationship between a temperature of a semiconductor wafer and a film thickness of a resist film.

2 is a diagram showing a schematic configuration of a resist coating system in which a coating apparatus according to an embodiment of the present invention is assembled.

3 is a longitudinal sectional view showing a mechanism for forming a temperature distribution on a workpiece.

4 is a cross sectional view showing a mechanism for forming a temperature distribution on a workpiece.

5 is a longitudinal sectional view showing another example of a mechanism for forming a temperature distribution on a workpiece.

6 is a schematic block diagram showing a coating apparatus according to an embodiment of the present invention.

7 is a schematic block diagram showing a coating apparatus according to another embodiment of the present invention.

8 is a longitudinal sectional view showing another example of a mechanism for forming a temperature distribution on a workpiece.

* Explanation of symbols for main parts of the drawings

1 processing unit 2 loader part

3: processor 4: semiconductor wafer

5: wafer cassette 6: cassette elevation

7: transfer mechanism 8 wafer transfer mechanism

10: centering guide 21: conveying device

21a: arm 22: passage

23: AD treatment device 24: heating device

25 cooling device 26 first coating device

27: second coating device 31, 48: plate

32a, 32b, 32c: cooling pipe (medium channel)

33a, 33b, 33c: refrigerant supply source (medium supply source)

34a, 34b, 34c: Temperature controller 35: Program setter

36a, 36b, 36c: temperature sensor 41, 51: chuck

42, 52: container 43: discharge nozzle

44, 54: cap 45, 55: motor

46: waste liquid hole 47, 56: exhaust port

49a, 49b, 49c: cooling tube 53: supply port

57: developer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus and a coating method for applying a coating liquid such as a resist and a developing solution to a coated object, for example, a semiconductor wafer.

In the pattern forming step of forming an electronic circuit pattern in a thin film state on a semiconductor wafer, first, a resist film is applied in a thin film state on a semiconductor wafer on which a thin film is formed, and then the resist film is exposed through a mask on which a predetermined pattern is formed. Then, it is developed to form a negative or positive resist pattern. Thereafter, the underlying thin film is etched using the resist pattern as a mask, a desired electronic circuit pattern is formed on the underlying thin film, and finally, the resist used as a mask is removed.

By the way, since the variation in the film thickness of the resist film formed by coating on the semiconductor wafer affects the precision of the resist pattern, it is required to make the film thickness uniform. In particular, with the recent high precision of patterns, the demand for uniformity of the film thickness of the resist film is further increased.

In this resist coating step, in order to increase the adhesion between the semiconductor wafer and the resist layer, the semiconductor wafer is subjected to an ADZ treatment under heating at about 90 ° C., and after cooling the processed wafer, the wafer is cooled by a spin coder. A resist is applied onto it. The coating at this time is performed by dropping the resist liquid in the center of the semiconductor wafer and then rotating the semiconductor wafer at high speed. The resist liquid dropped by this spreads to the peripheral part of a wafer, and the resist is apply | coated to the whole wafer surface.

However, in the case of applying the resist by spin coding in this way, a difference in volatilization speed of the resist solvent into the atmosphere occurs due to a difference in the turning speed at the center of the semiconductor wafer and the peripheral edge, and as a result, the center of the wafer. There is a difference in the film thickness of the resist film at the circumferential edges. In recent years, the diameter of a wafer tends to be large, and the difference in the film thickness as mentioned above becomes more remarkable.

In the developing step, the developer is supplied to the resist film after exposure, and is developed by holding the developer on the semiconductor wafer for a predetermined period. However, the developing speed becomes uneven due to the rotation of the semiconductor wafer at the time of supply of the developer, the rotation of the wafer after the supply of the developer, or the exhaust airflow.

The present invention has been made in consideration of such a situation, and an object thereof is to provide a coating apparatus and a coating method which can apply a coating liquid to a coating object such as a semiconductor wafer at a very uniform thickness.

Another object of the present invention is to provide a coating apparatus and a coating method capable of uniformly treating with a coating liquid.

According to the first aspect of the present invention, there is provided a support means for supporting a to-be-coated object, a coating liquid supplying means for supplying a coating liquid to the object to be coated, and a coating liquid supplied to the object to be rotated by applying the object. There is provided a coating apparatus including a rotating means that spreads over the entire surface of the object to be coated and a temperature distribution forming means for forming a temperature distribution on the object to be coated.

According to the second aspect of the present invention, there is provided a process for forming a temperature distribution on a workpiece, a step of supplying a coating liquid to a workpiece on which a temperature distribution is formed, and a coating solution on a workpiece on which a temperature distribution is formed. And a step of rotating the coated object and spreading the coating liquid supplied to the coated object on the entire surface of the coated object.

The inventors of the present application have repeatedly studied to form a coating liquid such as a resist on a coated object such as a semiconductor wafer with a uniform film thickness. I found it good to get rid of the difference in film thickness. That is, in the case where the coating liquid is applied to the object to be coated, for example, when the resist liquid is applied to the semiconductor wafer, as shown in FIG. 1, the higher the temperature of the semiconductor wafer as the coated body is, the resist liquid as the processing liquid The higher the volatilization rate of the solvent, the thicker the film thickness. On the contrary, the lower the temperature of the semiconductor wafer, the slower the volatilization rate of the solvent tends to be. Therefore, the coating liquid can be formed to have a uniform film thickness by forming a temperature distribution such that the temperature at the portion where the film thickness becomes thick or the temperature at the portion where the film thickness becomes thin due to a difference in turning speed or the like becomes high. have.

This invention is completed based on such a discovery of this inventor. The fact that the temperature of the semiconductor wafer has a great influence on the resist film is known in the prior art. For this reason, a cooling plate or a holder device for uniformly cooling the semiconductor wafer has been proposed in the related art (Japanese Patent Application Laid-Open No. 2-53939). No. 1-125358, No. 1-110430, No. 64-28918, etc.) or spinner heads with cooling means have been proposed (Japanese Patent Laid-Open No. 62-193248). However, these are aimed at cooling the semiconductor wafer uniformly and rapidly, and do not include the idea of forming a temperature distribution on the coated object as in the present invention. That is, the idea of forming a temperature distribution on a to-be-coated object to make a film thickness uniform is the inventor of the present invention for the first time.

In addition, the nonuniformity of the developing speed in the case of applying the developing solution to the coated object as the coating liquid is caused by the temperature of the peripheral edge of the coated object being lower than the temperature of the central part due to the influence of the airflow of the exhaust. Therefore, even in this case, it is possible to uniformly develop by forming a temperature distribution on the object to be coated.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

2 is a diagram showing a schematic configuration of a resist coating system in which a coating apparatus according to an embodiment of the present invention is assembled. This processing unit 1 is equipped with the loader part 2 and the processing part 3. The loader unit 2 includes a cassette elevator 6 for placing a plurality of wafer cassettes 5 (four in the drawing) on the wafer wafer 5 in which a plurality of semiconductor wafers 4 to be coated are housed so as to be movable up and down, and these wafer cassettes. The transfer of the wafer 4 between the transfer mechanism 7 and the processing unit 3 for carrying out the wafer 4 from the wafer 5 and carrying the wafer 4 into the cassette 5 is carried out. A wafer throwing mechanism 8 is provided. This flipping mechanism 8 has two stage pins 9 for placing the wafer 4 thereon, and a centering guide 10 for holding and aligning the circumferential edges of the wafer 4. The wafer 4 is flipped between the conveying apparatus 21 of the processing unit 3 to be described later by using a vertical motion mechanism (not shown).

The processing section 3 is for performing a predetermined processing on the semiconductor wafer, and has a passage 22 extending in the Y-direction (horizontal direction) in the drawing in the central portion, and a plurality of processings are performed to perform the respective processing on both sides thereof. The processing apparatus is formed. And the conveying apparatus 21 is formed so that it can move along the channel | path 22, and this conveying apparatus 21 enters and exits the wafer 4 with respect to each processing apparatus. The conveying apparatus 21 is equipped with the arm 21a which can move to a X direction (vertical direction), a Y direction (horizontal direction), an up-down direction, and a (theta rotation direction), and by this arm 21a the wafer ( 4) entry and exit is performed. As the processing apparatus, an ad zone (AD) processing apparatus 23, a heating apparatus 24, and a cooling apparatus 25 are formed on one side of the passage 22, and the first coating apparatus on the other side. (26) and the second coating device 27 are formed.

The AD processing apparatus 23 heats the semiconductor wafer 4 to 90 degreeC, for example, and processes it by HMDS etc. in order to improve the adhesiveness of the semiconductor wafer 4 and a resist before applying a resist.

The heating apparatus 24 pre-bakes a semiconductor wafer with a hotplate, for example, and evaporates the solvent remaining in the coating film after resist coating.

The cooling device 25 is for cooling the semiconductor wafer 4 after AD processing or after prebaking processing, the details of which will be described later. In this embodiment, the cooling device 25 functions as a means for forming a temperature distribution on the semiconductor wafer 4 as a to-be-coated body in the resist coating process described later. That is, the temperature distribution is formed on the wafer 4 during the cooling process of the semiconductor wafer 4.

As shown in FIG. 3 and FIG. 4, the cooling apparatus 25 is the cooling plate 31 in which the cooling pipe | tube 32a, 32b, 32c of which the plurality of (three in the figure) was embedded concentrically. Have Cooling tubes 32a, 32b, and 32c of the cooling plate 31 are connected to refrigerant sources 33a, 33b, 33c, respectively, and refrigerants, for example, water, are supplied from these refrigerant sources. It is circulated.

The coolant of the coolant sources 33a, 33b, 33c is maintained at different temperatures by the temperature controllers 34a, 34b, 34c, and the semiconductor wafer 4 on the plate 31. It is possible to form a predetermined temperature distribution.

The temperature distribution at this time is changed in accordance with conditions such as the viscosity of the resist liquid in the coating apparatus described later, the rotational speed of the wafer 4, the temperature at the time of coating and the like. Usually, the thickness of the circumferential edge portion of the wafer 4 tends to be thicker than the center portion due to the difference in the turning speed during coating, and accordingly, from the center of the cooling plate 31 to the circumferential edge correspondingly. The temperature distribution is formed so that the temperature is lowered. In any case, the temperature profile corresponding to the condition is programmed in advance in the program setter 35, and the temperature controllers 34a, 34b, 34c are based on the program set in the setter 35. The temperature of is set.

Further, as shown in FIG. 5, temperature sensors 36a, 36b, 36c are formed in the plate 31, and temperature controllers 34a, 34b, 34c are based on these values. The temperature of the coolant may be controlled by

In addition, the means for having such a temperature distribution may not be a problem, and may be electronic cooling, and the temperature distribution may be formed by arranging materials having different thermal conductivity in a concentric manner.

As shown in FIG. 6, the coating device 26 is formed above the chuck 41 holding the semiconductor wafer 4 by vacuum suction or the like, and on top of the chuck 41, and a resist liquid as a coating liquid is used as a wafer. (4) the discharge nozzle 43 for dropping onto the drop, the receiving container 42 for receiving the resist liquid dropped from the nozzle 43, and the cap 44 formed to cover the chuck 41. The resist liquid is applied to the semiconductor wafer 4 having a predetermined temperature distribution by the cooling device 25 described above to form a resist layer.

A motor 45 is connected to the chuck 41. The motor 45 rotates at high speed by the motor 45, and the semiconductor wafer held thereon is rotated at high speed. The rotation speed of the motor 45 is controlled according to a predetermined program by a control device (not shown).

The resist liquid contained in the accommodation container 42 drops from the nozzle 43 to the semiconductor wafer 4 through a filter, a bellows pump, a color back valve, and the like (not shown).

The cap 44 prevents the resist liquid sprinkled from the peripheral edge of the semiconductor 4 from scattering around when the resist liquid is dropped onto the semiconductor wafer 4 and then applied by rotating the wafer 4. In order to do so, the waste liquid hole 46 and the exhaust port 47 are formed in the bottom part, and waste liquid collection | recovery and the exhaust in the cap 44 are performed, respectively.

In addition, the cap 44 is capable of vertical movement, and at the time of carrying in and out of the semiconductor wafer, the chuck 41 is lowered to a position exposed from the center upper portion of the cap 44 to facilitate the carrying in and out of the semiconductor wafer. .

The second coating device 27 may have the same structure as the coating device 26, or may be a developing device after exposure. When used as a developing apparatus, by forming an exposure apparatus at the right end of the passage 22 in FIG. 2, a series of operations from resist application to development are possible.

As shown in FIG. 7, the developing apparatus is formed above the chuck 51 and the chuck 51 for holding the semiconductor wafer 4 by vacuum suction or the like, and supplies the developer onto the wafer 4. And a supply unit 53 having a plurality of nozzles, a receiving container 52 for receiving the developer supplied from the supply unit 53, and a cap 54 formed to cover the chuck 51. The motor 55 is connected to the chuck 51, whereby the chuck 51 is rotated. The developer is supplied to the semiconductor wafer 4 on the chuck 51, a layer of the developer is formed on the semiconductor wafer 4, and the developer is held for a certain time.

When supplying the developing solution, the wafer is rotated in order to spread the developing solution over the entire surface of the wafer in a short time. To this end, the development speed is changed by the difference in the circumferential speed of the wafer.

The exhaust port 56 is formed in the bottom part of the cap 54, and the inside of a cap is exhausted from this exhaust port 56. As shown in FIG. This developing process is performed while evacuating the inside of the cap 54 with the developing solution 57 placed on the semiconductor wafer 4. At this time, the temperature of the peripheral edge of the semiconductor wafer becomes lower than the temperature of the central portion due to the airflow of the exhaust, and the developing speed of the peripheral edge tends to be slow. Therefore, after prebaking before the semiconductor wafer is brought into the developing apparatus, the wafer is placed into the cooling apparatus 25 and cooled to form a temperature distribution in which the temperature at the peripheral edge thereof is higher than the temperature in the center portion, and the temperature distribution is maintained. The development speed can be made uniform by developing with this.

Next, the processing operation in the resist processing unit having the above configuration will be described. First, a mechanism in which the semiconductor wafer 4 before processing is taken out from the cassette 5 by the transfer mechanism 7 in the loader portion 2 and the wafer is picked up by the stage pin 9 from the transfer mechanism 7. It is received at (8) and is centered by the centering guide (10).

Subsequently, the semiconductor wafer 4 is loaded into the conveying apparatus 21 of the processing section 3 from the pouring mechanism 8, and is first loaded into the AD processing apparatus 23 by the conveying apparatus 21. In this AD processing apparatus 23, the semiconductor wafer 4 is heated to about 80 to 100 DEG C in an HMDS atmosphere and subjected to AD processing. After the AD processing, the semiconductor wafer 4 is conveyed by the conveying apparatus 21 and carried into the cooling apparatus 25. In the cooling device 25, as described above, the semiconductor wafer 4 is placed on the cooling plate 31 having a predetermined temperature distribution by flowing the refrigerant through the cooling pipes 32a, 32b, and 32c. The semiconductor wafer 4 is formed with a temperature distribution corresponding to the temperature distribution of the cooling plate 31.

Thus, the semiconductor wafer 4 in which the temperature distribution was formed is conveyed to the coating device 26 by the conveying apparatus 21. In the coating device 26, the semiconductor wafer 4 is vacuum-adsorbed to the chuck 41 with the cap 44 lowered. While the temperature of the semiconductor wafer 4 is slightly changed by the influence of the ambient atmosphere, the temperature distribution itself maintains substantially the temperature distribution formed in the cooling device 25.

After the wafer 4 is adsorbed by the chuck 41, the arm 21a of the conveying apparatus 21 is pulled back, the cap 44 is raised, and resist coating is performed. In this resist coating, first, the resist liquid drops from the discharge nozzle 43 onto the wafer 4 on the chuck 41, and then the chuck 41 rotates at a high speed at a predetermined rotation speed in accordance with a predetermined program. By this, the resist liquid spreads to the peripheral edge of the semiconductor wafer 4 and is applied to the entire surface of the wafer 4.

In this case, due to the difference in circumferential speeds in the central portion and the peripheral edge portion of the semiconductor wafer 4, the peripheral edge portion usually tends to have a thick resist film thickness. By forming the temperature at (4) so that the temperature of the peripheral part of it becomes lower than the temperature of the center part, the volatilization rate of the solvent of the wafer peripheral part can be made later than the center part, whereby or due to the difference in the speed of the film thickness You can get rid of the car.

Thus, the semiconductor wafer 4 in which the resist film was formed uniformly is conveyed to the heating apparatus 24, and is prebaked here, and the solvent in a coating film evaporates.

In the case where the second coating device 27 is a developing device, the semiconductor wafer 4 is cooled by the cooling device 25 with the temperature distribution at its circumferential edge portion being high and the temperature at the center portion having a low temperature distribution, and then exposed. It is brought into the developing apparatus.

In the developing apparatus, the semiconductor wafer 4 is adsorbed to the chuck 51 in a state where the temperature distribution formed by the cooling device 25 is substantially maintained, and the plurality of supply portions 53 are provided with the cap 54 exhausted. The developer is supplied to the semiconductor wafer 4 from the nozzle of.

In this case, since the inside of the cap 54 is exhausted, the temperature of the peripheral edge portion of the semiconductor wafer 4 tends to be lowered, and the developing speed of the peripheral edge portion tends to be lowered. The development speed can be made uniform by forming a temperature distribution so that the edge part becomes high temperature.

In the above embodiment, the temperature distribution of the semiconductor wafer 4 is formed by the cooling device 25 prior to the coating process or the developing process, but it is also possible to form a predetermined temperature distribution on the semiconductor wafer during the coating or developing process. .

For example, as shown in FIG. 8, around the chuck 41 of the cooling device 26, the cooling tubes 49a, 49b, ( It is also possible to form a ring-shaped cooling plate 48 in which 49c) is embedded, and to allow the semiconductor 4 held on the chuck 41 to contact the plate 48. Also in this case, the cooling tubes 49a, 49b, and 49c are supplied with refrigerants having different temperatures, respectively, to form a temperature distribution, and the temperature distribution corresponding to the temperature distribution to the semiconductor wafer 4 placed thereon. Can be formed, and the film thickness of the wafer can be made uniform.

In this way, even when the temperature distribution is formed in the semiconductor wafer 4, not only the cooling method for supplying the coolant to the cooling tube but also means such as electronic cooling may be employed. In addition, the temperature distribution may be formed by heating with a heater or the like as well as cooling.

In addition, in the above embodiment, the case where the resist liquid is applied and the case where the developer is applied are described, but in general, the present invention can also be applied to an apparatus for forming a coating film by applying the coating liquid to the coating body.

In addition, the present invention is intended to solve the unevenness of the coating treatment occurring between the peripheral edge portion and the center portion of the object to be coated, but in the above example, the temperature distribution was formed concentrically, but as long as the unevenness of the treatment was eliminated, It is also possible to employ | adopt arbitrary temperature distributions, such as temperature distribution which makes a temperature different locally, and a step shape temperature distribution as needed. In addition, although the semiconductor wafer was demonstrated as an example to apply, it is not limited to this, It can also apply to the process of a photomask, an LCD board | substrate, and a square top board.

Claims (4)

A coating method for applying a resist to a workpiece, wherein the resist is supplied to the workpiece, and the temperature distribution on the surface of the workpiece is controlled to form a resist layer having a uniform thickness. And a step of controlling the evaporation rate of the solvent of the resist on the coated body, and a step of spreading the resist on the entire surface of the coated object by rotating the coated object, wherein the temperature distribution is carried out on the plate having the temperature distribution. And the plate has a plurality of ring-shaped medium supply passages, and the temperature distribution is formed on the plate by supplying a medium having a different temperature to each medium supply passage. . A coating method for applying a developing solution to a coated object, the step of supplying a developing solution to the coated object, and a step of controlling the developing speed of the coated object by controlling a temperature distribution on the surface of the coated object. And spreading the developer on the entire surface of the workpiece by rotating the workpiece, wherein the temperature distribution is achieved by placing the workpiece on a plate having a temperature distribution, wherein the plate has a plurality of plates. And a ring-shaped medium supply path, wherein a temperature distribution is formed on the plate by supplying a medium of different temperature to each medium supply path. The coating method according to claim 2, wherein the temperature distribution controls the temperature of the peripheral edge portion to be higher than the temperature of the central portion. A coating method for applying a resist or a developer to a coated object, comprising: supplying a resist or a developer to the object to be coated, forming a temperature distribution on the object, and rotating the object to be coated And spreading a resist or developer onto the entire surface of the object, wherein the temperature distribution is achieved by placing the object on a plate having a temperature distribution, and the plate is provided with a plurality of ring-shaped media supply paths. And a temperature distribution is formed on the plate by supplying a medium of different temperature to each medium supply passage.