JPS6324621A - Coating applicator of photoresist - Google Patents

Abstract

PURPOSE:To reduce the dispersion of thickness of coating films, by providing a coating applicator with a steam generator of an organic solvent to delay drying. CONSTITUTION:A coating applicator is provided With a steam generator 15. In the main body of the steam generator 15, xylene of negative resist as a solvent 16 is contained Which is heated by a heater 17, and the steam of the solvent 16 is spouted on the surface of a wafer 1 from a spray nozzle 18. In order to spout the steam only at the time of coating, a shutter 19 and a safty hole 20 are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] Unexploded aJ [Among the manufacturing processes of semiconductor devices, this relates to an apparatus that performs spin coating of photoresist.

BACKGROUND ART Photoresists are mainly used as masks for etching and ion implantation in the molding process of VLSIt-centered semiconductor devices.

In order to increase the speed and integration of VLSI, patterns have become finer and submicron processing has become required.

For photoresist coating 1ci, a rotary coating machine is used, and as shown in FIG. Rotating torque is applied by a spin motor 6vc to the 0-rotation shaft 3, which is connected to a vacuum pump 5vc through a vacuum pump 4.When a certain amount of photoresist 8 falls from the dropping nozzle 7 onto the semiconductor substrate l, the spin motor 6 starts.

Normally, the rotational speed of the spin motor 6 is set at a constant acceleration region of 10t after the photoresist 8 dropped in the low-speed rotational region 9 is spread over the entire surface of the semiconductor substrate 1, as shown in FIG.
- When the semiconductor substrate 1 passes through and reaches the high speed rotation area 11, the excess photoresist is scraped off by centrifugal force.Then, the semiconductor substrate 1 is dried for 2-3 minutes in a nitrogen atmosphere at 100°C, and then subjected to the next alignment exposure. transported to the process.

[Problem that the invention seeks to solve]

Semiconductor substrate 1 coated with photoresist in this manner
A cross-sectional view of the photoresist 8 is shown in FIG. 3, and the film thickness of the photoresist 8 applied to the surface of the semiconductor substrate 10 is thinner at the center portion 12 and the peripheral portion 13, and thicker at the middle portion 14 (generally referred to as pile-up). There is a tendency.

Internal variation (uniformity) of film thickness from wafer to wafer is ±2%.

The variation (reproducibility) between wafers is often within ±3%.

Another problem is that the step coverage for the pattern on the wafer may be on the verge of breaking as shown in FIG. 4, or may become overhanging as shown in the ficS diagram.

In particular, regarding film thickness, during alignment exposure, we use monochromatic light with a wavelength of 4000 to a, oooo.
1. Refract heavy metal to film thickness t1μ immediately after coating of photoresist.
5, if the film thickness variation of 1/4 wavelength is 600 people or LOOO people, the interference light of the photoresist film will be reversed in brightness, so the variation will be ±300 people (±3%).
If the contrast is not stopped within this range, the contrast of the microscope image becomes blurred or disappears due to lack of contrast, making it impossible to perform accurate eye alignment, which has become a serious problem.

The present invention involves adding an organic solvent vapor generator to a conventional photoresist spin coater to delay drying.9. This is intended to reduce variations in coating film thickness.

[Means to solve all problems]

The film thickness and step coverage of the spin-coated f'L7t photoresist are determined by the drying process of the photoresist.

　　　.

By pouring the vapor of the organic solvent that makes up the photoresist, it is possible to delay the drying of the photoresist during one-turn coating, and to reduce the variation in the thickness of the photoresist coating. A good friend.

〔Example〕

Misfire - ○ - As an example, a steam generator 15 is attached to the conventional spin coater shown in FIG. 1.

For example, OMR as a solvent 16 in the main body 15 in the steam generator.
-83 (product name) - Negative resist xylene t
- For positive resists such as 0FPR (trade name), add ethyl cellosolve acetate and use n1 heater 17 for about 1
The wafer was heated to 00° C. and the vapor of the solvent 16 was poured onto the surface of the wafer 1 from the spray port 18. Furthermore, a shutter 19 and a safety hole 20t are provided for pouring steam only during application.

Misfire-〇As another example, steam generator 1 of sg1 diagram
The ultrasonic humidifier shown in Fig. 7 is used instead of 50s.

This fL has 1 main body 15, 16 7 solvents such as xylene or ethyl cell solve acetate, and an ultrasonic sensor 214.
Excavity is caused and fog is generated.

In this case, although the safety valve 20i is provided, the ultrasonic vibrator 2
Since the generation of fog can be controlled by turning off the power source 1, a shutter is not necessary.

[Effects of the invention] This process has been improved, making it easier to adjust the photoresist spin coating machine, and reducing the variation in inner film thickness from wafer to wafer by ±1%.
, the 111JI variation between wafers was within ±2%, and the variation could be suppressed to about 70%. In addition, by adjusting the coating conditions (viscosity of the photoresist and rotational speed profile of the spin motor of the rotary coating machine), the step coverage can be adjusted to, for example, the state on the verge of cutting off in Figure 5 and the overhang in Figure 6. An ideal cross-sectional shape can be obtained by keeping the sgy diagram constant between spin and spin.
An example 1 of the rotary speed profile is shown in FIG.

This is thought to be due to the ability to control the solvent drying rate of the photoresist 8.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows a spin motor rotation speed profile of a photoresist rotary coating machine, Fig. 3 shows the cross-sectional shape of the photoresist coating thickness distribution, and Fig. 4 shows the cross-sectional shape of the photoresist coating film thickness distribution. 5 shows the cross-sectional shape of the wafer in an overhang state on the wafer 8 step, FIG. 6 shows the ideal cross-sectional shape at the wafer step stop, and FIG. 7 shows another embodiment of the present invention. Example VC shows an ultrasonic humidifier. 1... Semiconductor substrate (wafer), 2...
・Vacuum chuck, 3...Hollow rotating shaft%4...
...Coupler, 5...--Vacuum pump, 6...
...Spin motor, 7...Dripping nozzle, 8
... Photoresist, 9 ... Low speed rotation part of spin motor, 10 ... Rising part of high speed rotation of spin motor, 11 ... High speed rotation part of spin motor Rotating part, 12... Central part of the semiconductor substrate (wafer), 13... Peripheral part of the semiconductor substrate (wafer). 14-・・・Intermediate part of semiconductor substrate (wafer), 1
5...Steam generator or ultrasonic humidifier, 16.
... Solvents such as xylene txtz and ethyl celnorb acetate, 17 ... Heater of steam generator, 18 ... Spray nozzle, 19 ... Shutter, 20. ...-Safety hole. ) 1 Anatomy Gou Z episode 31 ¥4-teka 6 (branch) Numa 7 @ 5 groups

Claims (1)

[Claims] A photoresist coating machine characterized by spin coating a photoresist in an atmosphere of photoresist solvent vapor.