JPH0963921A - Resist curing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cure a resist without discoloring the resist at all by ultraviolet ray irradiation by avoiding the particle adhesion to a wafer back within this resist curing device. SOLUTION: A cavity part 10 including a wafer 23 back is formed on a sample base 1 so as to feed liquefied gas directly coming into contact with the wafer 23 to the cavity part 10 and then the member in direct contact with the wafer 23 back is eliminated so that the liquefied gas may be brought into direct contact with the wafer 23 back to enhance the cooling effect by the heat of vaparization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist hardening apparatus for hardening a resist on a wafer in a photolithography process.

[0002]

2. Description of the Related Art Usually, a resist hardening apparatus coats a photoresist mask on the surface of a wafer, performs exposure patterning and develops the resist, and then 2,000 to 4 by an ultraviolet lamp.
While irradiating the wafer with high-intensity ultraviolet light (wavelength of 300 nm or more) of 000 mW / cm ² , the temperature of the wafer sample holder is raised from room temperature to about 200 ° C. at a heating rate of 5 to 10 ° C./sec. To cure the resist.

FIG. 3 is a schematic sectional view showing an example of a conventional resist curing apparatus. Conventionally, in this type of resist curing apparatus, for example, as shown in FIG. 3, a sample holder 18 on which a cooling pipe 21 and a heater pipe 19 are built-in and a wafer 23 is placed is mounted.
Then, the wafer 23 was equipped with the UV lamp 16 for irradiating the high-intensity ultraviolet light 22.

Further, the temperature of the sample holder 18 is controlled by the heater controller 20 which controls the heater current of the heater tube 19 and the cooling temperature controller 8 which controls the temperature of the cooling water in the cooling tube 21.

[0005]

In the conventional resist curing apparatus described above, since the entire back surface of the wafer is placed in direct contact with the sample holder, residual particles adhere to the mounting surface of the sample holder. It is easy, and the adhesion of particles is about 100 times that of other semiconductor production facilities.
As a result, the particles adhering to the back surface of the wafer fall to the wafer surface of the lower stage during transfer of the carrier, etc., and the particles adhere to the wafer surface, significantly reducing the yield of the subsequent steps and contaminating heavy metal contained in the particles. However, there is a problem that the above causes a problem of contamination in the subsequent process.

Further, although the temperature of the sample holder is controlled by the built-in heater tube and cooling tube, the temperature of the wafer rises rapidly due to the radiant heat of light having a long wavelength contained in the ultraviolet rays, which causes the temperature transfer. There is a problem that it takes time to stabilize the temperature within a certain range in cooling from the sample holder, which has a slow response. As a result, the resist is discolored due to overheating of the wafer due to the radiant heat of the ultraviolet rays, which causes a serious defect in pattern exposure and transfer on the wafer in the subsequent exposure step.

Therefore, an object of the present invention is to provide a resist curing apparatus capable of smoothly controlling the temperature of the wafer without adhering particles to the wafer and curing the resist without discoloring the resist.

[0008]

A feature of the present invention is that in a resist curing apparatus that exposes a pattern on a resist of a wafer which is a semiconductor substrate, develops the resist, and hardens the resist, a high illuminance of irradiating the surface of the wafer with ultraviolet rays. A lamp, a sample holder on which the wafer is placed, a spray nozzle for supplying a liquefied gas to a space formed on the sample holder including the back surface of the wafer, and a temperature sensor for detecting the temperature of the wafer. A liquefied gas control unit that controls the flow rate of the liquefied gas according to the temperature detected by the temperature sensor.

Further, it is desirable to provide an exhaust mechanism for reducing the pressure in the space.

[0010]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a resist curing apparatus according to an embodiment of the present invention. As shown in FIG. 1, this resist curing apparatus forms a space 10 including the back surface of a wafer 23 and an exhaust port 7 communicating with the space 10 on a sample holder 1, and sprays a liquefied gas into the space 10. The spray nozzle 2, the temperature sensor 3 that detects the temperature of the outer peripheral portion of the wafer 23 in the space 10, and the temperature detection signal of the temperature sensor 3 are input to adjust the flow rate of the liquefied gas from the liquefied gas supply unit 6. The liquefied gas control unit 4 for controlling the control valve 5 and the flow rate adjusting valve 8 is provided. Otherwise, it is the same as the conventional example.

Next, in the operation of this resist curing apparatus, first, the wafer 23 is placed on the sample holder 1 and the UV lamp 1
The radiant heat from the high-intensity ultraviolet light 22 emitted from the wafer 6 controls the supply amount of the atomized liquefied gas to the space portion 10 so that the surface temperature of the wafer 23 does not rise to a temperature of, for example, 300 ° C. or higher. Is to cool to a suitable temperature.

To this end, the temperature of the wafer 23 of the temperature sensor 3 which is in direct contact with the outer peripheral portion of the back surface of the wafer 23 is input to the liquefied gas control unit 4 as a detection signal, and the temperature of the wafer 23 is 100 to 200 ° C. Within the range, the liquefied gas control unit 4 performs cooling by the automatic opening / closing operation of the control valve 5 which supplies the liquefied gas through the flow rate adjusting valve 8 adjusted to a preset flow rate by the input temperature detection signal. There is. Further, the vaporized liquefied gas supplied to the space 10 is discharged to the outside of the device through the exhaust port 7.

In this way, since there is no intervening substance contacting the back surface of the wafer 23, unlike the conventional case where the sample is placed on the sample stand, particles are hardly attached. Further, since the liquefied gas is in direct contact with the wafer 23, the liquefied gas atomized and sprayed comes into contact with the wafer 23 and is vaporized, and the vaporization heat cools the wafer 23 quickly to allow smooth temperature control. .

The liquefied gas used for this cooling is preferably inexpensive nitrogen gas. Further, in order to prevent the wafer 23 from being lifted by the supply pressure of the liquefied gas, it is necessary to stop the supply pressure of the liquefied gas to such an extent as to support the weight of the wafer 23 and to throttle the advance flow rate adjusting valve 8.

FIG. 2 is a schematic sectional view of a resist curing apparatus according to another embodiment of the present invention. As shown in FIG. 2, this resist curing apparatus includes a vacuum pump 14 for exhausting the liquefied gas in the space 10 through an exhaust pipe 13 in order to make the space 10 a negative pressure, and a pressure for the space 10. That is, the pressure control unit 11 that detects the total amount of the exhaust gas and controls the opening degree of the exhaust control valve 12 is provided. The rest is the same as the resist curing apparatus shown in the above-mentioned embodiment.

As described above, by controlling the opening degree of the exhaust control valve 12 regardless of the supply pressure of the liquefied gas from the spray nozzle 2, the pressure in the space 10 is kept constant at a negative pressure, so that the wafer 23 and the liquefaction are liquefied. As the degree of contact with the gas increases, the contact strength between the outer peripheral portion of the wafer 23 and the sample holder 1 increases,
There is an advantage that the leak of the liquefied gas from the minute gap of the wafer 23 is reduced and the temperature controllability of the space 10 is further improved.

[0018]

As described above, according to the present invention, by forming the space portion including the back surface of the wafer on the sample holder and supplying the liquefied gas for contacting the wafer to the space portion,
The effect of eliminating particles from the sample holder, vaporizing by direct contact with liquefied gas, cooling the wafer faster, smoothing the temperature control of the wafer, preventing discoloration of the resist due to radiant heat and hardening can be obtained. To be

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a resist curing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a resist curing apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing an example of a conventional resist curing device.

[Explanation of symbols]

 1,18 Sample holder 2 Spray nozzle 3 Temperature sensor 4 Liquefied gas control unit 5 Control valve 6 Liquefied gas supply unit 7 Exhaust port 8 Flow rate adjusting valve device 9 Pressure gauge 10 Space part 11 Pressure control unit 12 Exhaust control valve 13 Exhaust pipe 14 Vacuum Pump 16 UV Lamp 17 Temperature Controller for Cooling 19 Heater Tube 20 Heater Controller 21 Cooling Tube 22 High Illuminance Ultraviolet 23 Wafer

Claims (2)

[Claims] 1. A resist curing apparatus for exposing and developing a pattern on a resist of a wafer which is a semiconductor substrate to cure the resist, and a high-illuminance lamp for irradiating the surface of the wafer with ultraviolet rays, and a sample on which the wafer is mounted. A cradle, a spray nozzle that supplies a liquefied gas to a space portion including the back surface of the wafer formed on the sample cradle, a temperature sensor that detects the temperature of the wafer, and the liquefaction based on the temperature detected by the temperature sensor. A resist curing apparatus, comprising: a liquefied gas control unit that controls a gas flow rate. 2. The resist curing apparatus according to claim 1, further comprising an exhaust mechanism for reducing the pressure in the space.