JP2899766B2 - Method of removing resist from peripheral edge of substrate to be processed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for removing a resist from a peripheral portion of a substrate to be processed.

[Prior art]

The lithography process, which is one of the semiconductor manufacturing processes, is mainly divided into five processes: surface treatment, resist coating, exposure, development, and etching. A vacuum apparatus such as a projection exposure apparatus or an etching apparatus used in these steps employs a mechanical method of clamping a peripheral edge of a semiconductor wafer as a method of transporting the semiconductor wafer and fixing the semiconductor wafer to a processing table. Therefore, if the resist remains on the peripheral portion of the wafer, the resist is likely to be peeled off when the semiconductor wafer is transported, which is likely to cause particles on the wafer. Conventionally, in order to prevent the generation of particles due to the peeling of the resist at the peripheral portion of the wafer, a solvent for dissolving the resist is dropped on the resist layer at the peripheral portion of the semiconductor wafer to remove the resist at the peripheral portion of the wafer. Has been done since. The method of removing the resist at the peripheral portion of the wafer is described in, for example, JP-B-53-37706 and JP-A-55-12750.
JP-A-58-91637, JP-A-58-191434, JP-A-61-184824, JP-A-62-54920, JP-A-60-94660 and the like. Have been. These conventional methods for removing the resist at the peripheral portion of the wafer include:
A resist-soluble solvent is simply applied to the periphery of the semiconductor wafer, and the temperature of the solvent is not adjusted.

[Problems to be solved by the invention]

However, when the resist film on the peripheral portion of the wafer after the removal of the resist on the peripheral portion of the wafer by the solvent for dissolving the resist was inspected in detail by the conventional method, as shown in FIG. It has been found that after the removal of the resist, a ridge 41 of the resist may be formed on the edge of the resist film 40. Even if the resist on the peripheral edge of the wafer is removed in this way, if there is a swelling of the resist, the swelling portion may come into contact with another object or be peeled off by vibration or the like, so that particles are easily generated. In view of the above, it is an object of the present invention to reduce the swelling of the resist after removing the resist at the peripheral portion of the substrate to be processed, and to reduce the generation of particles.

[Means for Solving the Problems]

According to the present invention, a substrate to be processed having a surface coated with a resist is provided on a turntable, and the substrate to be processed is rotated, and a solvent for dissolving the resist is supplied to a peripheral portion of the substrate to be processed, thereby forming In a resist removing method for removing a resist at a peripheral portion of a processing substrate, the rotation speed of the processing target substrate is set to a speed according to a diameter of the processing target substrate, a type of the resist, and a type of the solvent. The temperature of the solvent supplied to the peripheral portion of the substrate to be processed is controlled so as to optimize the resist dissolution rate.

[Action]

As a result of the study by the present inventors, it is considered that the swelling of the peripheral portion of the resist after removing the resist at the peripheral portion of the substrate to be processed by the solvent is caused when the resist is hardly dissolved by the solvent. In other words, it is considered that if the resist is not easily dissolved by the solvent, a mixture of the solvent and the resist that bounces off by colliding with the surface of the substrate to be processed remains on the periphery of the resist. The resist solubility (dissolution rate) of the solvent has temperature dependence. In the present invention, the rotation speed of the substrate to be processed is the diameter of the substrate to be processed, the type of the register,
The speed is set according to the type of the solvent, and the temperature of the solvent is controlled so as to optimize the register dissolution speed. Therefore, after removing the resist at the peripheral portion of the substrate to be processed, the peripheral portion of the resist is removed. The swelling can be prevented.

【Example】

Hereinafter, an embodiment of a method for removing a resist from a peripheral portion of a substrate to be processed according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a resist coating apparatus to which a method according to the present invention is applied. A semiconductor wafer 1 as an example of an object to be processed is vacuum-sucked on a disk-shaped mounting table 2 and temporarily adsorbed. Fixed. The mounting table 2 is rotatable by being connected to a rotation shaft of a rotation mechanism 3 having a stepping motor whose rotation speed can be pulse-controlled, for example. The semiconductor wafer 1 fixed by suction is rotated. In this case, the semiconductor wafer 1 is placed on the mounting table 2 in a state where the rotation center position of the mounting table 2 matches the center position of the semiconductor wafer 1. The drive and rotation of the stepping motor of the rotation mechanism 3 are as follows.
For example, it is controlled by a control pulse from a rotation control unit 4 including a computer. A resist supply nozzle 5 for dropping a resist solution is provided at a position above the mounting table 2 and substantially at the center of the wafer 1. A nozzle 6 for discharging a resist-soluble solvent such as butyl acetate or ECA to the periphery of the wafer is provided above a predetermined rotation angle position on the outer periphery of the wafer 1. The nozzle 6 is, for example, an injection needle having a needle hole having a diameter of 0.3 mm, and the tip of the nozzle 6 is positioned at the wafer 1.
Is provided, for example, at a position 2 mm away from the surface of the device. In this case, the nozzle 6 is mounted so that the solvent discharge angle is, for example, 45 ° with respect to the surface of the wafer 1 and the discharge direction is directed toward the outside of the wafer 1. The resist from the peripheral portion of the wafer 1 can be removed from the outer peripheral edge of the wafer 1 over a width of, for example, about 2 mm by the solvent from Step 6. The solvent is supplied to the nozzle 6 through a pipe 7. In the pipe 7, an opening / closing valve such as an air operation valve 8 and a suck back valve 9 are provided. The discharge amount from the nozzle 6 is determined, and the solvent is drawn back so that the excess solvent does not drip from the nozzle 6 when the suck back valve 9 closes the valve 8. Further, in the vicinity of the nozzle 6, in order to control the temperature of the solvent, the pipe 7 is covered with an outer pipe 10 to form a jacket structure, and a temperature control double pipe 11 is provided. The temperature-regulated water whose temperature has been adjusted by the thermostat 12 is supplied to the outer pipe 10 of the temperature-adjusting double pipe 11 by the circulation pump 13.
It is configured to circulate. The pipe 7 in the temperature control double pipe 11 may be formed in a coil shape in order to perform good heat exchange. In the case of this example, the constant temperature device 12 includes a heater 12A and a cooler 12B, and also includes a control device 12C. Then, the temperature of the hot water outlet side near the nozzle 6 in the outer pipe 10 is
The temperature is detected by the temperature sensor 14, and the temperature detection output is supplied to the control device 12C of the constant temperature device 12, and the control device 12C controls the heater 12A so that the detected temperature becomes equal to the temperature preset in the set temperature input means 15. And cooler 12B
Is controlled. The temperature at which the resist dissolution rate of the solvent is optimal is set in the set temperature input means 15. When the solvent is butyl acetate, the temperature is set to, for example, 60 ° C, and when the solvent is ECA, the temperature is set to, for example, 30 to 40 ° C. Next, the operation of the resist coating apparatus of FIG. 1 will be described below. First, the wafer 1 is placed on the mounting table 2 with its center aligned, and is vacuum-adsorbed and fixed to the mounting table 2. Thereafter, a predetermined amount of resist solution is dropped onto the wafer 1 by the nozzle 5, and the mounting table 2 is rotated by the rotating mechanism 3 to rotate the wafer 1 while evacuating, and the resist is fixed on the wafer 1 surface by centrifugal force. It is expanded to be thick. The above is the same as the normal resist coating operation. After the completion of the resist application, the resist at the peripheral portion of the wafer is removed over a width of, for example, 2 mm as follows. That is, the wafer 1 having the surface coated with the resist as described above is rotated by rotating the mounting table 2 by the rotating mechanism 3. In this case, the rotation speed is an optimum rotation speed that is predetermined according to the wafer diameter, the type of the resist, and the type of the solvent, and is, for example, 2000 to 3000 rpm. Then, the opening / closing valve 8 is opened, and a solvent such as butyl acetate is obliquely oblique to the peripheral portion of the wafer 1 from the nozzle 6 at a discharge rate of 10 to 15 cc / min. It is discharged in the direction. At this time, the solvent is supplied to the temperature control
The temperature is adjusted to the set temperature by the temperature-regulated water controlled by 12, for example, 60 ° C. when the solvent is butyl acetate, and 30 to 40 ° C. when the solvent is ECA. That is, although the resist solubility (dissolution rate) of the solvent has temperature dependency, the solvent temperature is adjusted to the optimum temperature determined from the relationship between the dissolution rate and the resist bulge around the wafer. . With this solvent, the resist on the peripheral portion of the wafer 1 is removed with a width of 2 mm from the edge of the wafer 1. At this time, the temperature of the wafer 1 may be room temperature (for example, 21 to 23 ° C.). As described above, the resist at the peripheral portion of the wafer is removed. However, since the temperature of the solvent is adjusted so that the dissolution rate of the resist is optimized, the peripheral portion of the resist film after the removal of the resist at the peripheral portion of the wafer 1 is removed. No swelling of the resist occurs at the ends. Incidentally, when the resist is excessively dissolved by the solvent, the resist is excessively dissolved over the required width of 2 mm or more, but according to the present invention, the optimal dissolution rate is controlled by controlling the temperature of the solvent. No excessive melting occurs. Further, since the solvent is ejected from the nozzle 6 toward the outside of the wafer at an ejection angle inclined with respect to the surface of the wafer 1, the rise of the peripheral edge of the resist film is reduced together with the temperature control of the solvent. Can be. In the above example, a thermostat 12 using a heater and a cooler was used for temperature control. However, as shown in FIG. 2, a thermomodule 20 using, for example, a Peltier element 21 instead of the thermostat 12 was heated. Control device 22
So that the temperature detected by the temperature sensor 14 becomes the temperature set by the set temperature input means.
May be controlled. Further, as shown in FIG. 3, a thin-film heating element 31 is attached to the outer periphery of the temperature regulating water pipe, and the power supplied to the thin-film heating element 31 is controlled by the control device 32 (for example, the current is controlled by PWM. )
Then, a configuration may be adopted in which the temperature of the temperature control water is set to the set temperature.

【The invention's effect】

As described above, according to the present invention, the resist dissolution rate is controlled by controlling the temperature of the solvent for removing the resist at the peripheral edge of the substrate to be processed. The bulge of the edge can be reduced, and therefore, the generation of particles at the time of transporting the substrate to be processed can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a resist coating apparatus to which the present invention is applied, FIG. 2 and FIG. 3 are views for explaining another example of the temperature control means, and FIG. It is a figure for explaining a fault of a method. 1; Wafer 2; Mounting table 3; Rotating mechanism 6; Nozzle for dissolving resist-soluble solvent 7; Piping 11; Double pipe for temperature adjustment 12; Constant temperature device 13; Circulation pump 14; Temperature sensor 15; Set temperature input means

Claims (1)

(57) [Claims] 1. A substrate to be processed having a surface coated with a resist is provided on a turntable, and the substrate to be processed is rotated.
A resist removing method for supplying a solvent for dissolving the resist to the peripheral portion of the substrate to be processed and removing the resist at the peripheral portion of the substrate to be processed, wherein the rotation speed of the substrate to be processed is Diameter and
The type of the resist and the speed according to the type of the solvent are set, and the temperature of the solvent supplied to the peripheral portion of the substrate to be processed is controlled so as to optimize the resist dissolution speed. A method for removing a resist from a peripheral portion of a substrate to be processed.