JPH02307567A - Rotary coating device - Google Patents

Abstract

PURPOSE:To permit coating film to be distributed in a uniform thickness by providing covering means enclosing each side of a wafer in a larger area than the surface of the wafer and rotatable in the same direction as the wafer. CONSTITUTION:A wafer 7 is held securely on the mounting surface of a rotary means 5 by a suction pipe 6 and covering means 8 and 9 are provided which are rotatable in an area larger than the surface of the wafer 7 enclosing each side thereof and in the same rotary direction as the rotary means 5. When the covering means 8 and 9 are being rotated, a gas present therebetween is caused to rotate due to its own viscosity and by being drawn by the rotary force of the covering means 8 and 9 to create a gaseous stream rotating in the same direction as the covering means. Due to the rotation of the wafer 7 in the same direction as the covering means 8 and 9, relative rotary speed between the wafer 7 and the gaseous stream becomes smaller. Consequently, the relative speed of the gas impinging against the peripheral edge of the wafer 7 becomes smaller, causing a decrease in cooling rate to take place at the peripheral edge of the wafer 7. As a result, the coating film at the peripheral edge of the wafer 7 is less liable to solidification due to a rapid cooling, whereby coating can be applied in a uniform film thickness.

Description

[Detailed Description of the Invention] () Already Required] Regarding the spin coating device, especially 11! of the device! Regarding a rotary coating device that uses centrifugal force to spread the liquid coating agent dropped onto the surface of an object to be coated, such as a wafer, placed on a surface, the film thickness distribution of the liquid coating agent dropped onto the surface of the object to be coated, such as a wafer. The purpose of this method is to suppress unevenness in the spread of film, especially in the film thickness distribution near the orientation flat area, by rotating the object to be coated, such as a wafer, about a direction perpendicular to the surface of the object. , a rotating means for spreading the liquid coating agent dropped onto the surface of the object to be coated by centrifugal force; and a rotating means that rotates in the same direction as the rotating means while covering both sides of the object with a surface wider than the surface of the object to be coated. and a covering means that rotates at a rotation speed.

[Industrial application field]

The present invention relates to a spin coating device, and more particularly to a spin coating device that uses centrifugal force to spread a liquid coating agent dropped onto the surface of an object to be coated, such as a wafer, placed on a mounting surface of the device.

(Prior Art) FIG. 4 shows a resist spin coating device according to a conventional example.
4(a) is a top view thereof, and FIG. 3(b) is a sectional view taken along line A-A in FIG. 4(a).

In the figure, 1 is a rotating means, and 2 is a wafer 13 placed on the mounting surface of the rotating means l.
3! This is a suction tube that is evacuated to fix the position and rotation.

Next, a case will be described in which a resist solution is spread on a wafer surface using this spin coating apparatus.

First, an appropriate amount of resist liquid 4 is dropped onto the center of the surface of the wafer 2 using a pipette (not shown) or the like. Next, the rotating means 1
When the wafer 2 is rotated, the resist solution 4 spreads from the center to the periphery of the wafer 2 due to the centrifugal force caused by the rotation, forming a resist film with a constant thickness determined by the viscosity of the resist solution, the rotational speed of the wafer 2, etc. Ru.

[Problem to be solved by the invention]

However, when the thickness distribution of the resist film spread over the wafer surface is examined in detail, it is not necessarily uniform, and the resist film is locally thick at the edges near the circumference of the wafer surface.

FIG. 5 is a diagram for explaining this, and FIG. 5(a) is a partial top view of a wafer on which a resist film has been spread.

Figure (b) is a cross-sectional view showing the film thickness distribution of the resist film in the area indicated by B-B in figure (a), and figure (C) is a cross-sectional view showing the resist film thickness distribution in the area indicated by line C-C in figure (a). FIG. 3 is a cross-sectional view showing the film thickness distribution of the film.

As shown in Figure (b), at the edge of the wafer surface, a thick resist film wall with a thickness of 2 to 3 μm is formed in an area several mm from the green, while on the inside, a wall of resist film with a thickness of 2 to 3 μm is formed over the entire wafer surface. A resist film having a uniform thickness of about 1 μm is formed.

In addition, as shown in the same figure (C), in the orientation flat part of the wafer, 10 to 2
A thick resist film is formed over a wide range up to 0 mm.

Note that the resist film becomes thicker at the edges of the wafer because the edges collide violently with the surrounding gas during rotation and are rapidly cooled.As a result, the resist at the edges hardens fastest, and then the resist film at the edges hardens. It is thought that this is because the resist spread over the area hardens and accumulates one after another.

In this way, in areas where the resist film is formed thickly, compared to other areas where the resist film is thin, the exposure amount for pattern exposure is insufficient, and a proper pattern is not formed, causing the semiconductor This causes a decrease in the yield of non-defective products of the equipment.

The present invention was created in view of the problems of the prior art, and it solves the problem of uneven spreading of the film thickness distribution of the liquid coating agent dropped onto the wafer surface, especially the uneven spreading of the film thickness distribution near the orientation flat part. The purpose is to suppress

[Means to solve the problem]

The present invention has a rotating means that rotates the object to be coated, such as a wafer, about a direction perpendicular to the surface of the object to be coated, thereby spreading the liquid coating agent dropped onto the surface of the object to be coated by centrifugal force. , while covering both sides of the object to be coated with a surface wider than the surface of the object to be coated,
Solve the above issues.

[Effect]

When the coating means provided on both sides of the surface of the object to be coated, such as a wafer, rotates, the gas sandwiched between the coating means is also pulled by the coating means due to the viscosity of the gas itself, and this causes the gas to flow in the same direction as the coating means. A rotating air current is created.

By the way, since the object to be coated is also rotating in the same direction as the coating means, the relative speed between the rotation speed of the object to be coated and the rotation speed of the airflow becomes small. For this reason, the relative speed of the gas colliding with the peripheral edge of the surface to be coated decreases, and the cooling speed at the peripheral edge of the target body also decreases. As a result, the solidification of the coating film at the peripheral edge of the object to be coated due to rapid cooling is reduced, so that the thickness distribution of the coating film can be made uniform.

In particular, the thickness distribution of the coating film on the orientation flat portion of the wafer can be made much more uniform than in the past.

It should be noted that the larger the covering means provided on both sides of the wafer surface is, the more uniform the gas flow between the wafers can be. The shorter the distance, the more the viscosity of the gas can be utilized, so the shorter the distance, the better, within a practical range.

However, since it is desirable that the rotational speed of the wafer be the same as the rotational speed of the gas between the coating means, the rotational speeds do not necessarily have to be the same as long as the rotational directions of the wafer and the coating means are the same.

〔Example〕

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

FIG. 1 shows a resist spin coating apparatus according to an embodiment of the present invention; FIG. 1(a) is a top view thereof, and FIG.
A sectional view taken along line D-D in a).

Figure (C) is a sectional view taken along line E-E in Figure (a).

In the figure, 5 is a rotating means, and 7 is a 6-inch diameter wafer placed on the mounting surface of the rotating means 5.

Reference numeral 6 denotes a suction tube that is evacuated to fix the wafer 7 to the IllW surface of the rotating means 5.

Further, 8 is a lower covering means with a diameter of 12 inches attached to the rotating means 5, and is rotatable together with the rotating means 5. 9 is an upper covering means, and four spacers 10
It is removably engaged with the lower covering means 9 via.

Next, a case will be described in which a resist solution is spread onto a wafer surface using a spin coating apparatus according to an embodiment of the present invention.

First, the upper covering means 9 is removed and the wafer 7 is placed on the mounting surface of the rotating means 5, and then the suction tube 6 is evacuated and the wafer 7 is moved to v! Fixed on page 11.

Next, an appropriate amount of resist liquid 11 is dropped onto the center of the wafer 7 using a pipette (not shown), and then the rotating means 5 is rotated 4. When rotated at OOO rpm, the wafer 7 and the upper and lower coating means 8, 9 also rotate. As a result, the resist liquid 11 on the surface of the wafer 7 spreads from the center to the periphery of the wafer 7 due to centrifugal force, and when the resist liquid 11 has sufficiently spread, the rotation of the rotating means 5 is stopped.

FIG. 2 is a diagram showing the film thickness distribution of the resist film on the surface of the wafer 7 formed in this way, and FIG. b) is a cross-sectional view showing the film thickness distribution of the resist film in the region indicated by F-F in FIG. FIG. 3 is a cross-sectional view showing thickness distribution.

As shown in FIG. 2B, the thickness of the resist film near the peripheral edge of the wafer 7 is approximately the same as the thickness of the resist film in the inner region, and is made uniform. Further, as shown in FIG. 2C, the region of the thick resist film in the orientisilane flat portion of the wafer is also extremely small, and is reduced to about 2 to 3 mm from the edge of the wafer. As a result, a substantially uniform thickness distribution of the resist film can be obtained over the entire surface of the wafer. If necessary, this thick portion can be further removed using a stripping solution or the like to further improve the uniformity of the film thickness distribution of the resist film.

Therefore, the pattern exposure of the resist film is uniform over the entire wafer, which can greatly contribute to the yield of high-integration, ultra-fine semiconductor devices that require highly accurate pattern formation.

In addition, in the embodiment of the present invention, the coating means 5 having a diameter of 12 inches was used for the wafer 7 having a diameter of 6 inches.
The size of the covering means can be changed as appropriate depending on the size of the wafer, etc.

Furthermore, when forming a circuit pattern on a mask or reticle, it is necessary to make the thickness of the applied resist uniform, so the application of the present invention is not limited to wafers.

Furthermore, it is considered that the narrower the gap between the coating means provided above and below the wafer surface, the more controllable the air flow between the coating means, and therefore, the narrower -M is considered to be better.

FIG. 3 is a sectional view of a spin coating apparatus according to another embodiment of the present invention.

In this figure, 12 is the wafer s! The rotating means has a recessed surface, and the depth of the recessed portion is so shallow that the upper surface of the wafer is hidden when the wafer 14 is placed in the recessed portion.

Further, 15 is a lower covering means attached to the rotating means 12, and is rotatable together with the rotating means 12. Reference numeral 9 denotes an upper covering means, which can be moved up and down by a lifting means (not shown) to change the distance from the upper surface of the wafer 14, and when the rotating means 12 rotates, it rotates in the same direction and at the same rotational speed. do.

According to this embodiment, the orientation flat portion of the wafer 14 can be hidden in the recess of the rotating means 12, so that direct collision of the end portion of the orientation flat with the airflow during rotation can be avoided. , no need to be quenched. Therefore, it is possible to further prevent the resist spread in the vicinity of the orientation flat from being rapidly cooled and becoming locally thick.

〔Effect of the invention〕

As explained above, according to the present invention, a covering means that rotates in the same direction as the object to be coated such as a wafer is provided, and the viscosity of the gas sandwiched by the covering means is used to cover the airflow around the object to be coated. The relative speed to the application body can be reduced.

Therefore, the cooling speed by the air flow at the peripheral edge of the coated body surface is also reduced, so that the solidification of the coating film at the peripheral edge of the coated body is reduced, and the thickness distribution of the coated film can be made uniform.

In particular, the thickness distribution of the coating film on the orientation flat portion of the wafer can be made much more uniform than in the past.

For this reason, the pattern n light applied to a coating film, such as a resist film, is uniform over the entire wafer, which can greatly contribute to the yield of high-density, ultra-fine semiconductor devices that require highly accurate pattern formation. .

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating spin coating and transfer according to an embodiment of the present invention, and FIG. 2 is a diagram showing Il! of a resist film according to an embodiment of the present invention. FIG. 3 is a diagram showing a spin coating transposition according to another embodiment of the present invention; FIG. 4 is a diagram showing a conventional spin coating device; FIG. 5 is a diagram showing a conventional spin coating device;
FIG. 3 is a diagram showing the film thickness distribution of a conventional resist film. (Explanation of symbols) 1.5.12...Rotating means, 2.7.14...Wafer, 3.6...Suction tube, 4.11...Resist liquid, 8.9.15. 16... Covering means, 10... Spacer, 13... Recessed part.

Claims (3)

[Claims] (1) a rotating means that rotates the object to be coated such as a wafer about a direction perpendicular to the surface of the object to be coated, thereby spreading a liquid coating agent dropped onto the surface of the object to be coated by centrifugal force; A rotary coating device comprising: a coating means that rotates in the same rotational direction as the rotation means while covering both sides of the object to be coated with a surface wider than the surface of the application object. (2) A rotary coating device according to claim 1, wherein the coating means rotates at the same speed as the rotating means. (3) A rotary coating device characterized in that a recessed portion having a depth approximately equal to the thickness of the object to be coated is provided on the object-to-be-coated surface of the rotating means according to claim 1.