JPS5882521A - Spinner - Google Patents

Abstract

PURPOSE:To equalize the film thickness of a photoresist film throughout the whole face of a wafer by a method wherein a chuck table is formed with a material having low thermal conductivity. CONSTITUTION:The chuck table 26 of a spinner 10 is formed by poly hexaethylene fluoride having low thermal conductivity. In this way, even if heat reaches the table 26 from a driving motor 28, a bearing portion or the like through a rotary shaft 30, the heat hardly conducts to a semiconductor wafer 14 and photoresist dropped on the wafer 14 is suppressed from heating. Therefore, xylene or the like included as a solvent in the photoresist is volatilized at a region above the table 26 and the photoresist on the region is prevented from producing high viscosity. Accordingly, the photoresist forms a photoresist film having equal film thickness on the whole region of the wafer 14 by a centrifugal force generated by the high-speed rotation of the table 26.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to xeyt used for photoresist coating, etc.
Km″″″6° (For the manufacture of semiconductor devices, microfabrication is performed using +7 lithography technology, but in this case,
A photoresist film is used as a mask for photoetching, and a spinner is used to form the photoresist film.

Conventionally, the formation of a photoresist film as a mask for photoetching has been carried out as follows. 1.
Shoulder opening 1@S 1-114877 (911m118so
-setot) No. 11K Using a spinner like the one shown in the picture, even if it is 1ztoo ■
■The film thickness is 70mm when placed on a rotatable chuck table of φ.
00 to 8000 μm photov cyst membrane t-formation,
Drop 2 to 5 cc of photoresist onto the conductor tube from the nozzle, and place it on the chuck table at 300 to 500 rpm.
e! 1. Rotate for 1-2 seconds at 4000-700
A photoresist film having a desired thickness of 7,000 to 8,000 Å is formed by rotating at a high speed of 0 r, pm for 12 to 15 seconds.

However, in the case of a conventional spinner, as shown in Figure 1,
The thickness of the photoresist film 16 coated on the semiconductor wafer on the chuck table 12 of the spinner 10 in order to form a photoresist film with a thickness of, for example, yooo The inventors have discovered that a difference in unevenness that is even larger than that of the conventional one occurs. That is, the photoresist mts is thickest at the center;
Slightly outer circumference 1I from above the outer periphery of the chuck table 12
It is the thinnest in the donut-shaped region of ll], and it gradually becomes thicker from this thinner region toward the outer circumference. When such a film thickness difference occurs in the photoresist film 46, the resolution g1tL during exposure of the photoresist film decreases, and there is a drawback that fine processing cannot be performed by the photoetching process and a fine pattern cannot be obtained with high precision. I also discovered that.

In order to make the photoresist film have such a film thickness t, the inventor of the present invention determined that the rotation speed of the spinner when changing from low speed rotation to high speed rotation, If#, which is the usage condition of the spinner, was Experiments were conducted in which the wafer setting conditions on the chuck table surface, the photoresist dropping condition, and the atmosphere condition by adjusting the exhaust air speed in the spinner were variously changed, but it was not possible to obtain a photoresist film with a satisfactory uniform thickness. won. At 70, the semiconductor Ueno 1 was cleaned with K11-based cleaning solution before applying Photoresist), and the Ueno
I tried dropping the photoresist using jelly which had been cooled by the volatilization of the cleaning solution, but the viscosity of the photoresist dropped onto the wafer increased too quickly and the film thickness became uneven. I see a trend, my friend. On the contrary, we conducted an experiment in which photoresist (1) was applied with only the chuck table preheated, but in this case, the film thickness variation of the photoresist film was much more pronounced, and the uniform thickness was ◇ Therefore, the present inventor conducted further intensive research in order to obtain a photocyst film with a uniform thickness, and discovered the following phenomenon. In other words, the chuck table attached to a conventional spinner has a large load and has a poor start-up during rotation, but it is made of stainless steel, which is strong, has excellent chemical resistance, and has good machining accuracy, and is lightweight and has low inertia. Made of aluminum, which is small and easy to work with.

However, since these chuck tables are made of metal, they must have very high thermal conductivity. Therefore, if a larger semiconductor wafer of 75 mm diameter and 1001 diameter fathom is placed on a chuck table made of a metal body with a diameter of 50 inches, and photoresist is dropped onto the surface of this sea urchin, the chuck table made of a metal body and this area Thermal interference occurs between the wafer and the wafer that are in contact with the wafer, forming a thermal circulation closed circuit, and the photoresist on this part of the wafer quickly dries and solidifies. When volatile substances such as xylene try to volatilize, the heat of vaporization is given by the thermal closed circuit, so the photoresist on the inner part protrudes from other parts, that is, the chuck table. (The area around the chef 1 is air, which is a gas with extremely poor thermal conductivity. Consider that there is no negotiation between the photoresist and its surroundings, and the situation is thermally insulated, so that the thermally closed circuit described above is not formed. It was discovered that when dried, the viscosity increased and KFJ finally solidified.Also,
The heat generated by the motor, which is used as a drive source for rotating the chuck table, and the frictional heat generated between the shaft connecting the motor and chuck table and its O-bearing, are As a result, the temperature of the chuck table increases, which causes volatile substances such as xylene, which is a solvent contained in the photoresist, to volatilize, causing the upper part of the chuck table to evaporate. A new prospect is that photoresist tends to dry and assimilate faster than other parts. As a result, as mentioned above, the thickness of the photoresist film above the chuck table is the thickest, while the photoresist in the donut-shaped area on the outer periphery side is pulled toward the outer periphery due to the centrifugal force caused by the rotation of the chuck table, but the photoresist film on the inner side It was discovered that since the photoresist is already drying and solidifying, the amount of photoresist that is drawn toward the outer circumference is limited, and only the donut-shaped region becomes thinner.

Therefore, in view of the above-mentioned drawbacks and problems of the conventional spinner as well as the study results of the present inventors as mentioned above, it has excellent characteristics such as being able to obtain a photoresist film with a moderate thickness. SUMMARY OF THE INVENTION It is an object of the present invention to provide a spinner.

In order to meet this purpose, the spinner according to the present invention reduces the thermal exchange between the photoresist spread on the wafer and the chuck table by forming the chuck table with a material with poor thermal conductivity. As a result, the thickness of the photoresist film is made uniform over the entire surface of the wafer.

In the present invention, non-metallic materials with low thermal conductivity are preferably used as materials for the chuck table, such as fluororesin, which is extremely hard, easy to mechanically process, and has little change in shape over time. Polyhexafluoroethylene, rubber, etc. are suitable.

Hereinafter, the present invention will be described in further detail using examples illustrating the present invention.

FIG. 2 is a schematic diagram of a spinner for applying photoresist according to an embodiment of the present invention, and FIG. 3 is an enlarged explanatory diagram thereof.

The spinner for applying photoresist shown in c has a generally circular processing container 18t which is formed by an upper cup 20 and a lower cup 22, and the upper cup 20 is K-shaped so that it can be opened and closed with respect to the lower cup 22. Even when the cup 20 is in the closed state 1, it is a member that is introduced into both cups 20.2218 and defines the air inlet path.

Reference numeral 26 denotes a chuck table on which an object to be processed, such as a rasp or a semiconductor wafer 114, is placed and vacuum-suctioned, and is rotatable. This chuck table 26#i
A rotating shaft aot-a passing through the bottom wall of the lower cup 22 is connected to a drive motor 2BK b. In the figure, 29 is a rotating wheel 300 bearing.

A semiconductor wafer 1 is mounted on the chuck table 26 and the rotating shaft 30.
4 vacuum suction holes 32 (FIG. 4) are formed for vacuum suction. Further, a plurality of holes 34 communicating with the vacuum suction holes 32 are formed on the upper wafer mounting surface of the chuck table 26, as shown in FIGS. 4 and 5.

In the chuck table 26 of this embodiment, heat generated between the drive motor 28, the rotating wheel 30, and the bearing 29 is conducted to the chuck terrace 26 via the rotating shaft 30, and the heat generated between the drive motor 28, the rotating wheel 30, and the bearing 29 is conducted from the chuck table 26 to the semiconductor layer above it. In order to prevent the heat from being transmitted to the wafer 14, it is made of polyhexafluoroethylene, which has low thermal conductivity. Therefore, in this embodiment, even if the heat from the drive motor 28 and the bearing section is transmitted to the chuck table 26 through the rotating shaft 30, the chuck table 26 is made of polyhexane (polyhexane) ethylene, which is made of a non-metallic material. Since the material has low conductivity, the heat from the rotating shaft 3G is directly transferred to the chuck table zsc+jk.
9. There is very little need to heat the chuck table. However, since the chuck table has such a low thermal conductivity, the heat from the chuck table is applied to the semiconductor wafer placed on the chuck table, resulting in heat generation. Therefore, even if a thermal exchange occurs between the chuck table and the semiconductor wafer placed in contact with the ξ side, forming a thermal circulation closed circuit, there is no significant heat flow in the thermal closed circuit. It doesn't flow. Therefore, even if a volatile substance such as xylene, which is a solvent contained in the photoresist deposited on the wafer, attempts to volatilize, it cannot be obtained through the closed circuit of the vaporization heat tube necessary for volatilization. Therefore, only the central portion of the photoresist film 36 held on the semiconductor wafer 14 does not dry and become highly viscous, and a uniform photoresist film of 36 ft can be obtained.

A companion photoresist dropping nozzle 38 for dropping photoresist 14 degrees above the semiconductor wafer is provided near the center of the clay wall of the upper cup 20.

A plurality of photoresist dropping nozzles 3B can be provided as shown in FIG. 3 in order to separately drop photoresist films having different viscosities.

The photoresist material to the photoresist dropping nozzle 38 is
A photoresist source 42 is supplied in metered quantities through a regulator 44 having a pressurized metering pump air valve, a solenoid pulp, and a check valve, which are controlled by a controller 40 .

The upper cup 20 also has a treatment liquid supply nozzle 4 for supplying a surface treatment liquid for cleaning the surface of the wafer.
6 is provided diagonally.

The processing liquid such as thinner is supplied to the processing liquid supply nozzle 46 to clean the photoresist-coated surface of the semiconductor wafer 14 before applying the photoresist, and is supplied from the processing liquid source 4B to the processing liquid controlled by the control device 40. The treatment source supply nozzle 46 passes through a regulator 50 consisting of a pressure pump and a control valve, and a filter 52.
The supply is disgusting.

However, in addition to the wafer front surface treatment means, this spinner also uses one of the plurality of photoresist dropping nozzles 38 as a gas supply nozzle. A surface cleaning method that removes dust and the like adhering to the surface of the wafer 14 by injecting gas such as nitrogen gas from the nozzle is increasingly being applied. Gas is supplied to the gas supply nozzle (using the photoresist dropping nozzle 38) from the gas source 56, the pressure reduction regulator 5B, and the regulator 6 controlled by the controller [40].
0 and a photoresist flow path system, and a gas flow path system including a filter 62 and the like.

Attached to the bottom wall of the lower cup 22 is a narrow discharge pipe 64 for discharging air, a surface treatment liquid such as thinner, and excess photoresist. The substances sucked into the discharge pipe 64 are discharged in the direction of the arrow (see FIG. 3). Due to the suction force into the discharge pipe 64, the air that has been sucked in through the gap 24 between the upper cup 20 and the lower cup 22 also flows as shown by the arrow mark. This air has the effect of preventing excess photoresist from scattering around due to the centrifugal force caused by the rotation of the semiconductor wafer 14, and from rebounding and adhering to unwanted surfaces such as the wafer surface. Furthermore, a cylindrical net-like body 66 is provided around the inner periphery of the lower cup 22 to turn unnecessary photoresist into a mist and prevent the photoresist scattered from the wafer from bouncing back and approaching the wafer surface again. It is being

Note that 67 is a companion member whose purpose is to prevent photoresist from adhering to the back surface of the wafer.
As the chuck table 6 rotates, the gas around it rotates to generate an outward airflow between the member 67 and the back surface of the chuck table 26, thereby achieving the above object.

Next, the operation of this embodiment will be explained. First, prior to coating the photoresist, the semiconductor wafer 14 placed on the chuck table 26 of the spinner 10 is heated from a vacuum source (not shown) to the vacuum suction surface of the skeleton chuck table 26 through the vacuum suction hole 32 and the vacuum suction groove 34f. Adsorb onto the top. After this attack, the treatment liquid from Cape Shinna was sprayed from the surface treatment liquid supply nozzle 46 onto the surface of the semiconductor tool 14 to completely clean the surface.

Drying is performed by rotating the chuck table 26.

After completing the pretreatment of the wafer for photoresist application in this way, the photoresist film is dropped onto the center of the semiconductor wafer 14. At this time, the semiconductor sea urchin 14 of 1001φ is placed on the chuck table 26 of 50"φ, and a photoresist tube of 2 to 5 aC is dropped. In that case, the chuck table 26 #i is initially
, pom, for 2 seconds by the drive motor 28 to spread the photoresist over the top surface of the wafer, and then 5000 r, p,
By rotating at high speed for 12 to 15 seconds at m, a desired photoresist j [36] having a very uniform film thickness from the center to the outer periphery can be obtained on the upper mK of the semiconductor wafer 114.

In the present fII, the chuck table 26 of the spinner 10 is entirely made of polyhexafluoroethylene, which has low thermal conductivity, so that heat from the three-motion motor P28, bearings, etc. passes through the entire rotating shaft 30. Even if the photoresist reaches the chuck table 26, the photoresist is hardly transmitted to the semiconductor wafer 14, and the photoresist dropped onto the semiconductor wafer 14 is prevented from being heated. Therefore, xylene, etc. contained in the photoresist as a solvent is volatilized especially in the upper region (center region) of the chuck table 26, and only the photoresist in the line region is prevented from becoming highly viscous. A photoresist film having a uniform thickness is formed over the entire area of the semiconductor wafer 14 by the centrifugal force caused by the high speed rotation of the table 26.

In addition to the above-mentioned polyhexafluoroethylene, the material of the chuck table 26 may be any material with low thermal conductivity, such as various non-metallic materials such as fluororesin, rubber, etc. can be used.

It should be noted that it is not easily attacked by photoresist and its solvent such as xylene.

Table 1 shows examples of specific heat and thermal conductivity of various materials.

It can be seen that the non-metallic materials exemplified in Table 191 have extremely low thermal conductivity t- compared to metallic materials, and are suitable as materials for the chuck table of the spinner according to the present invention.

FIG. 6 is a partial sectional view showing another embodiment of the spinner according to the present invention. In this embodiment, the chuck table body 26 of the spinner is made of a metal material such as aluminum or stainless steel, and a coating layer 26B of polyhex7ethylene is provided on the surface of the chuck table body 26.

In this embodiment as well, conduction of heat from the drive motor 28 and the like to the photoresist film on the semiconductor wafer 14 is suppressed by the polyhexafluoroethylene coating layer 26B.

FIG. 7 is a partial sectional view showing another embodiment of the spinner according to the present invention. In this embodiment, only the wafer 1 sucking surface side of the chuck table body 26A of the spinner chuck table 26ii made of a metal material is covered with a coating layer 260 of fluororesin. In the case of this embodiment as well, the fluororesin coating layer 260 can suppress the conduction of energy from the drive motor 2B, etc. to the photoresist film on the semiconductor wafer 14, and the photoresist film with a uniform thickness can be prevented. t- can be obtained.

Next, the inventor will show the results of an experiment to determine how the thickness of the photoresist film coated on the semiconductor wafer on the chuck table changes depending on the material and diameter of the chuck table of the spinner. FIGS. 8 to 12 are diagrams showing the results of measurements made by the inventor of the present invention of the film thickness distribution of photoresist films on chuck tables of various materials and diameters using a Mystog thickness measuring machine manufactured by Yoshiyuki Co., Ltd., respectively. In these figures, one scale in the X-axis direction and the Y-axis direction corresponds to 3.8- of the actual dimension, and one scale in the Z-axis direction (film thickness) corresponds to 160- of the actual dimension.
This corresponds to the system. The dimensions of the semiconductor wafer 1 used were 901φ2 measurement range, that is, the illustrated range was 781φ.

FIG. 8 shows the film thickness distribution of photoresist II when a photoresist film is formed on the surface of a semiconductor wafer using a spinner having an aluminum chuck table having a diameter of 381φ. In this case, the average film thickness was 8650λ, the maximum film thickness was 8727A, and the minimum film thickness was Fi860ON. The central part of the film is thick, the donut-shaped region around its periphery is thin, and the outer layer side is even thicker, resulting in an uneven film thickness distribution.

Figure 9 shows the film thickness distribution of a photoresist film when a photoresist film is formed on the surface of a semiconductor using a spinner containing an aluminum chuck table with a diameter of 0.05 mm.The average film thickness in this case is as follows. was 5saIX, the maximum film thickness was 5yts; and the minimum film thickness was 8603A.

In this case as well, since the chuck table is made of aluminum having high conductivity, the thickness distribution of the photoresist film is non-uniform. Also, from a comparison with what is shown in FIG. 8, the trapezoid (mesa portion) formed by the non-uniform thickness of the photoresist film is
50-φ) It turns out that the bolt is compatible with K,
Additionally, as the boundary line between the thick and thin portions of the photoresist film changes with the difference in chuck table diameter, it is clear that the chuck table has a large effect on the thickness distribution of the photoresist film. Recognize·.

Figure 10 shows the film thickness distribution of a photoresist film when a photoresist film is formed on the surface of a semiconductor urchin using a chuck table spinner similar to that of Figure 9 except that the width of the vacuum suction groove is small. It is. Average film thickness in this case ti86021. In this case as well, the film thickness distribution of the photoresist film is unreliable, and the material of the chuck table has a strong effect on film thickness non-uniformity, and changing the shape of the vacuum suction groove can affect the film thickness distribution. It can be seen that it is difficult to resolve incurable cases.

FIG. 11 shows the film thickness distribution of a photoresist film when photoresist mt is formed on the surface of a semiconductor wafer using a spinner as shown in the embodiment of the present invention explained using FIGS. 2 to 5 WAt-. .

As mentioned above, the chuck table specifications are made of polyethylene hexane, and the chuck table diameter is 50 mm. In this case, the diagram om in Figure 11 is Kana 9th! As can be seen from the fact that the temperature is close to lK, a very uniform spreading thickness distribution can be obtained.

In this case, the average film IlI is B603^, and the maximum film thickness is the first
Figure 2 shows the film thickness distribution of the photoresist film when it is formed on the surface of the photoresist semiconductor sea urchin 15f using a chuck table made of rubber, and in this case also, the film thickness distribution is uniform. In this case, the minimum film thickness was 8579 μm.

As explained above, according to the present invention, it is possible to obtain a photoresist rt with an extremely uniform film thickness.

The spinner according to the present invention can be applied to film forming apparatuses made of various materials other than photoresist coating apparatuses.

[Brief explanation of the drawing]

Figure 1 is a partial schematic diagram of a conventional spinner.
Figure 2 is a schematic configuration diagram of a spinner according to an embodiment of the present invention, and Figure 3 is its main structure. FIG. 4 is a partial sectional view of one embodiment of the spinner according to the present invention, FIG. 5 is a plan view thereof, and FIG. 6 is another example of the spinner according to the present invention.
FIG. 7 is a partial sectional view of another embodiment of the spinner according to the present invention, and FIGS. 8 to 12 show chuck tables of various diameters and materials. FIG. 3 is a diagram showing a film thickness distribution tube of a photoresist film obtained by a spinner. 1G...Spinner, 14-...Semiconductor sea urchin, -126
...Chuck table, 2B...Drive motor, 29
...Bearing, 30...Rotating shaft, 3...Vacuum suction hole,
3. Groove. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 2 Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1. In a spinner equipped with a chuck table that can removably place a workpiece and is rotatable, a part of the chuck table is made of a material that is more thermally conductive than metal. A spinner characterized by being composed of low-profile members. 2. The spinner according to claim 1, wherein the chuck table is entirely constructed of a member having lower thermal conductivity than a metal material. 3. The spinner according to claim 1, wherein the chuck table is made of a metal material, and the outer surface of the chuck table is coated with a material having lower thermal conductivity than the metal material. 4. The spinner according to claim 1, wherein the member with low thermal conductivity is a non-metallic material. 5. The spinner according to claim 1, wherein the member with low thermal conductivity is made of fluororesin. 6. The spinner according to claim 1, in which polyhexafluoroethylene is used as the member with low thermal conductivity. 7. The spinner according to claim 1, wherein the thermally conductive ot%/% member is made of rubber.