JPH04253320A - Spin coating device - Google Patents

Abstract

PURPOSE:To make the film applied to the entire surface of a wafer uniform in thickness by eliminating the temperature difference caused by speed differences at each point in the radial direction on the wafer when coating liquids, such as resist and developing solution, are applied to the surface of the wafer while the wafer is rotated. CONSTITUTION:A plurality of heaters 10a-10d are concentrically arranged in a turntable 3 on which a wafer 1 is placed. The heaters 10a-10d give a temperature gradient to the wafer 1 in the direction opposite to the temperature gradient in the radial direction of the wafer 1. Therefore, the temperature difference in the radial direction of the wafer 1 can be corrected and the temperature becomes uniform over the entire area of the wafer 1. Since no viscosity difference occurs in the resist spread over the surface of the wafer 1, the film thickness of an applied film 3 becomes uniform.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin coating apparatus for applying a coating liquid such as a resist or a developer onto the surface of a wafer in the process of manufacturing semiconductor devices.

0002

2. Description of the Related Art In the manufacturing process of semiconductor devices, rotational coating (spin coating) is currently the mainstream when coating a coating liquid, such as a resist, on the surface of a wafer. In this spin coating, resist is dropped onto the surface of a wafer placed on a rotating table, then the wafer is rapidly rotated by the rotating table, and the centrifugal force spreads the resist over the wafer surface to form a coating film. It is something.

0003

[Problems to be Solved by the Invention] However, in the above-described spin coating, as shown in FIG. Thus, a speed difference occurs due to rotation at each position in the radial direction of the wafer 1, and the speed increases from the center to the outer circumference of the wafer 1. Therefore, as shown in graph B, a temperature difference occurs at each position in the radial direction of the wafer 1 due to the different speed of contact with the surrounding atmosphere, and the temperature decreases from the center to the outer periphery of the wafer 1. . As a result, a viscosity difference occurs in the resist that spreads over the surface of the wafer 1, and as a result, as shown in graph C, the thickness of the coating film 3 increases from the center to the outer periphery of the wafer 1. There was a problem in that the uniformity of the coating film thickness over the entire surface of No. 1 deteriorated.

[0004] Therefore, the present invention provides a rotary coating device that can eliminate temperature differences caused by speed differences at various positions in the radial direction of a wafer during rotary coating, and can improve the uniformity of the coating film thickness over the entire surface of the wafer. The purpose is to provide

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention provides a method for dropping a coating liquid onto the surface of a wafer placed on a rotary table, rotating the wafer by the rotary table, A rotary coating apparatus for forming a coating film on the surface of a wafer is provided with a temperature control means for regulating the temperature of the wafer.

[0006]

[Operation] According to the present invention configured as described above, since a temperature gradient opposite to the temperature gradient in the radial direction of the wafer is applied to the rotary table by the temperature control means, the speed at each position in the radial direction of the wafer is The temperature difference caused by the difference is corrected, and the temperature of the entire wafer becomes uniform. As a result, no viscosity difference occurs in the coating liquid that spreads over the surface of the wafer, and as a result, the uniformity of the coating film thickness over the entire surface of the wafer is improved.

[0007]

Embodiment FIG. 1 is a schematic diagram of a spin coating apparatus in a first embodiment. A disc-shaped rotary table 4 is rotationally driven by a motor 5, and the wafer 1 is held on the rotary table 4 by vacuum suction. A nozzle 6 is disposed above the center of the rotary table 4, and the resist 2 is dropped onto the surface of the wafer 1 from this nozzle 6.

The rotary table 4 is configured such that its temperature in the radial direction can be adjusted. That is, a plurality of heaters 10a, 1, for example, four heaters 10a, 1 are installed inside the rotating table 4.
0b, 10c, and 10d are buried concentrically. Here, from the heater 10a at the center to the heater 10d at the outer periphery,
The temperature is set such that the temperature increases as it goes further, thereby imparting a temperature gradient to the rotary table 4 in the radial direction. Although not shown, each heater 10 can be connected from the outside.
A rotating contactor can be used to energize a to 10d.

According to the spin coating apparatus configured as described above, the wafer 1 is held on the rotary table 4 by vacuum suction, and after the resist 2 is dropped onto the surface of the wafer 1 from the nozzle 6, the motor 5 is started, and the rotary table 4, that is, the wafer 1, is rapidly rotated. The resist spreads over the surface of the wafer 1 due to the centrifugal force, and a coating film 3 is formed on the surface of the wafer 1.

During this rotational coating, as shown in graph A in FIG. 2, a speed difference occurs at each position in the radial direction of the wafer 1. A temperature difference occurs at each position in the direction. Therefore,
A temperature gradient (graph C) opposite to the temperature gradient in the radial direction of the wafer 1 is applied to the rotary table 4 by each of the heaters 10a to 10d. In addition,
The temperature gradient of the wafer 1 can be experimentally detected in advance, and the temperature gradient of the rotary table 4 can be set based on this. However, since the heat capacity of the wafer 1 and the heat capacity of the rotary table 4 are different, the degrees of inclination of both temperature gradients are not necessarily the same.

In this way, since a temperature gradient opposite to the temperature gradient of the wafer 1 as shown in the graph B is applied to the rotary table 4 as shown in the graph C, the wafer 1
The temperature difference at each position in the radial direction is corrected, and the temperature of the entire wafer 1 becomes uniform as shown in graph D. Therefore, no viscosity difference occurs in the resist spread over the surface of wafer 1, and as a result, as shown in graph E, wafer 1
The thickness of the coating film 3 over the entire surface becomes uniform.

The temperature gradient of the rotary table 4 is set based on the temperature gradient of the wafer 1, but the temperature level of the entire rotary table 4 is determined by the heater 10a.
It can be adjusted appropriately by setting the entire temperature of ~10d. Thereby, it is possible to set the uniform temperature of the entire wafer 1 to the optimum temperature for forming the coating film 3.

Next, FIG. 3 is a schematic diagram of a spin coating apparatus in a second embodiment. In this second embodiment, a rotary table 4 having heaters 10a to 10d similar to those described above is used.
A plurality of, for example, four, temperature sensors 11a are installed near the surface of the
, 11b, 11c, and 11d are provided along the radial direction. Note that each temperature sensor 11a to 11d is connected to the wafer 1.
There are two possible configurations: one in which the temperature of the rotary table 4 is detected, and the other in which the temperature of the rotary table 4 is detected.

FIG. 4 is a block diagram of the temperature control system in the second embodiment. Each temperature sensor 11a to 11d is
The temperatures at multiple positions in the radial direction of the wafer 1 or rotary table 4 are detected, and signals corresponding to the detected temperatures are sent to the control unit 12. The control unit 12 controls energization of each heater 10a to 10d based on these signals.

According to this second embodiment, the temperature of the wafer 1 or rotary table 4 during spin coating is detected by each temperature sensor 11.
Since the temperature can be detected by the heaters 10a to 11d, the control unit 12 controls each heater 10a to 10d based on the temperature.
By controlling the temperature of the rotary table 4, the temperature of the rotary table 4 can be adjusted with higher precision, and the temperature of the wafer 1 can be made more uniform.

Next, FIG. 5 is a schematic diagram of a spin coating apparatus in a third embodiment. Multiple pieces below the rotary table 4,
For example, four nozzles 20a, 20b, 20c, and 20d are arranged along the radial direction, and each of these nozzles 20a
~20d to fluids 21a, 21b, 21c, 2, respectively
1d is sprayed onto the lower surface of the rotary table 4. Here, the temperature is set to increase from the fluid 21a at the center to the fluid 21d at the outer periphery, thereby imparting a temperature gradient to the rotary table 4 in the radial direction.

According to this third embodiment, the fluids 21a-2
1d has an extremely wide temperature adjustment range, and in some cases, the temperature of the rotary table 4 can be lowered below normal temperature by using a fluid with a negative temperature, so the temperature level of the entire rotary table 4 can be adjusted over a wider range. be able to. Note that if a plurality of concentric grooves 22a, 22b, 22c, and 22d are formed on the lower surface of the rotary table 4, the fluids 21a to 21d can be sprayed while being separated from each other, making it easier to control the temperature of the rotary table 4. Can be done effectively.

The embodiments of the present invention have been described above, but
The present invention is not limited to the embodiments, and various effective changes and applications can be made based on the technical idea of the present invention. For example, the temperature gradient in the present invention does not necessarily have to be a gradient with a constant rate of change as in the embodiments. Further, as a temperature control means, in the first and second embodiments, a heater is embedded inside the rotary table, but the heater may be disposed close to the bottom of the rotary table to indirectly heat the rotary table. In the third embodiment, the fluid was sprayed onto the lower surface of the rotary table, but the fluid may be made to flow inside the rotary table. Furthermore, various effective configurations other than heaters and fluids can be employed. Note that the present invention is not limited to a resist spin coating device, but can be applied to a spin coating device for various coating liquids such as a developer.

[0019]

[Effects of the Invention] As explained above, according to the present invention,
By applying a temperature gradient opposite to the temperature gradient in the radial direction of the wafer to the rotary table, the temperature difference caused by the speed difference at each position in the radial direction of the wafer during spin coating is eliminated, and the temperature of the entire wafer is made uniform. can do. Therefore, it is possible to effectively prevent the occurrence of a viscosity difference in the coating liquid that spreads over the surface of the wafer, and it is possible to make the uniformity of the coating film thickness over the entire surface of the wafer extremely good.

Furthermore, according to the present invention, when applying a temperature gradient to the rotary table, the temperature level of the entire rotary table can be adjusted as appropriate, so that the temperature of the entire wafer can be made uniform. The temperature can be set to the optimum temperature for forming a coating film, and the range of application to various coating liquids is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a spin coating apparatus in a first embodiment.

FIG. 2 is an explanatory diagram for explaining the effects of the present invention.

FIG. 3 is a schematic diagram of a spin coating device in a second embodiment.

FIG. 4 is a block diagram of a temperature control system in the second embodiment.

FIG. 5 is a schematic diagram of a spin coating device in a third embodiment.

FIG. 6 is an explanatory diagram for explaining problems in conventional spin coating.

[Explanation of symbols]

1 Wafer 2 Resist 3 Coating film 4 Rotary table 10a-10d Heater 21a-21d Fluid

Claims (1)

[Claims] 1. A rotary coating apparatus that drops a coating liquid onto the surface of a wafer placed on a rotary table, and rotates the wafer using the rotary table to form a coating film on the surface of the wafer. 1. A rotary coating device comprising a temperature control means for controlling the temperature of the spin coating device.