JPS6378536A - Coating equipment - Google Patents

Abstract

PURPOSE:To apply a photo-resist in uniform thickness by disposing an approaching plate at a position where a coating liquid scattered by the centrifugal force of the upper section and lower section of a spin chuck, on which a wafer is placed and which is turned, does not reach and is not reflected directly. CONSTITUTION:An applicator is formed in structure in which a clean gas is sprayed forcibly from the upper section and lower section of a spin chuck 2, on which a wafer 1 to be treated is placed and which is rotated. Approaching plates 5, 6 are mounted at positions where a coating liquid scattered by centrifugal force does not reach and is not reflected directly on the upper surface and lower surface of the spin chuck 2 while the gas does not form stagnation on the surface and rear sides of the wafer 1 and is discharged as a laminar flow. The temperature of the gas 11 supplied is controlled, and an exhaust mechanism exhausts the gas 11 in a treating chamber by ejector action. Accordingly, a photo-resist film, on which no foreign matter adhere and which has uniform thickness, can be acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating apparatus, and particularly to a processing technique that is effective for use in cleaning and drying semiconductor thin plates in the manufacture of semiconductor devices.

[Conventional technology]

2. Description of the Related Art Photolithography technology is frequently used in the manufacture of semiconductor devices such as ICs (integrated circuits) and LSIs (large-scale integrated circuits). In this photolithography, a film such as photoresist is formed on the main surface of a semiconductor substrate (wafer). Known methods for forming this film include a drop spin coating method, a spray spin coating method, a paper spin coating method, and the like. In addition to photoresist, coating materials include dopant materials, spin-on glass (SOG) materials, polyimide resin materials, and the like.

The technology for coating photoresist on a semiconductor substrate is as follows:
There is a technique as described in Japanese Patent Application Laid-Open No. 59-121839. The outline of the technology according to this document is as follows. That is, the chamber is constructed by arranging an upper chamber portion and a lower chamber portion, each of which has a hyperbolic cross section, substantially parallel to each other with a gap therebetween. Also disposed within the chamber are a chuck for a sample to which a solution is to be spin-coated and its spin head. Further, exhaust gas is exhausted from the gap.

[Problem that the invention seeks to solve]

As the degree of integration progresses from 1 Mbit to 4 Mbit to 16 Mbit, as in the case of memory LSIs, it becomes necessary to miniaturize the element package size from 1 micron to submicron dimensions. With this submicron rule,
The size of foreign matter that adheres to the wafer is also considered to be a problem, even if it is even microscopic.

That is, in the submicron rule, the size of foreign particles that directly lead to defects is 0.1 μm or less.

When considering the above-mentioned coating apparatus on the premise of the above, a vortex is generated by the rotation of the wafer, and the generated vortex interferes with the air flow supplied into the chamber, resulting in a stagnation region. The inventors have revealed that as a result, the air flow acting on the wafer is no longer uniform, and the accuracy of the coating film thickness is reduced. It was also revealed that foreign particles that bounced off after being stirred floated in the stagnation area and re-attached to the wafer.

An object of the present invention is to provide a coating device that can control coating film thickness with high precision.

Another object of the present invention is to provide a coating device in which foreign matter is less likely to adhere.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Means for solving problems]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the coating apparatus of the present invention has a structure in which clean gas is forcibly blown from the upper and lower parts of a spin chuck that rotates while heating a wafer as an object to be processed. In addition, proximity plates are provided on the top and bottom surfaces of the spin chuck at positions where the coating liquid scattered by centrifugal force reaches directly and is not reflected, and these proximity plates prevent the gas from stagnation on the front and back sides of the wafer. It is exhausted as a laminar flow without forming. Furthermore, the temperature of the supplied gas is controlled. Further, the exhaust mechanism is configured to exhaust gas within the processing chamber by an ejector action.

[Effect]

According to the above-described means, the photoresist applied to the main surface of the wafer is spread along the main surface of the wafer by centrifugal force.
Although the photoresist liquid is scattered from the edge of the wafer, the scattered photoresist liquid is exhausted along with the laminar gas flow, so that photoresist coating without foreign matter adhesion can be achieved. In addition, if the temperature of the supply gas is adjusted and coating is performed at a temperature below the saturated vapor pressure of the photoresist, the photoresist on the main surface of the wafer will be difficult to evaporate and the thickness will not vary due to evaporation. Since the film thickness is determined only by rotation, a photoresist film of uniform thickness can be obtained. In addition, photoresist particles scattered from the wafer edge are not reflected by the proximal plate and adhere to the wafer surface, and clean gas is supplied to the center of the upper and lower surfaces of the spin chuck. Because the gas flows and is forced out by the ejector action, the gas flow becomes laminar and flows in the radial direction in the processing chamber without stagnation, so scattered photoresist particles do not re-attach to the wafer surface and foreign particles are removed. A stick-free application can be achieved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

The drawing is a sectional view showing essential parts of a coating device according to an embodiment of the present invention.

The coating device has its main surface (top surface) as shown in the drawing.
A spin chuck 2 on which a wafer 1, which is a workpiece to be processed, is placed
have. This spin chuck 2 holds the wafer 1 by vacuum suction. Further, the spin chuck 2 is attached to the tip of a rotating shaft 4 rotated by a spin motor 3.

Therefore, the spin chuck 2 is connected to the spin motor 3.
It rotates at the desired rotational speed by driving.

Proximity plates 5.6 are provided above and below the spin chuck 2, respectively. These proximal plates 5.6 are located outside the area where the photoresist liquid, or photoresist droplets, are directly scattered from the surface of the wafer 1 due to the centrifugal force and rotating airflow caused by the rotation of the wafer 1. , and located closest to the wafer 1. Further, the upper proximity plate 5 has a structure that gradually becomes lower toward the periphery, so that the airflow flowing inside the processing chamber 7 becomes a laminar flow.

Further, the outer circumferential edge of the proximal plate 5 extends longer than the outer circumferential edge of the wafer 1 to prevent photoresist droplets scattered from the outer edge of the wafer l from re-adhering to the upper surface of the wafer 1.

On the other hand, a gas supply pipe 9 is connected to the center of the vicinity vi, 5 via a gas supply port 8. Furthermore, a gas supply section 10 with a supply gas temperature adjustment mechanism is attached to the gas supply pipe 9. The gas supply section 10. Gas supply pipe9. In the gas supply mechanism constituted by the gas supply port 8 , the gas 11 at a desired temperature sent from the gas supply section 10 is evenly distributed from the gas supply port 8 through the gas supply pipe 9 and delivered into the processing chamber 7 . supply to. By supplying this gas 11, the processing chamber 7 becomes under positive pressure, and the scattered photoresist droplets are prevented from flowing back into the processing chamber 7 again.

On the other hand, a photoresist dripping nozzle 12 is arranged at the center of the proximity plate 5. This photoresist dripping nozzle 1
2 is attached to the tip of a photoresist supply pipe 14 extending from the photoresist supply section 13 . Also,
Since the photoresist supply pipe 14 extends inside the gas supply pipe 9, the photoresist supply pipe 14
The temperature of the gas 11 becomes approximately the same as that of the gas 11 as a result of the influence of the gas 11 flowing outside. Therefore, the gas supply unit 10
1, the temperature of the photoresist liquid 15 in the photoresist supply pipe 14 can be controlled. The photoresist supply section 13. Photoresist supply pipe 14. A coating liquid supply mechanism consisting of a photoresist dropping nozzle 12 supplies a photoresist liquid 15 to the center of the main surface of the wafer 1 as shown by cross-hunting.

The center portion of the lower proximity plate 6 is the rotation shaft 4 of the spin motor 3.
The rotary shaft 4 is rotatably and airtightly attached to the outer part of a hollow housing 16 via a seal 17. Furthermore, a gas supply port 18 is provided around the rotating shaft 4 at the upper part of the housing 16 and communicates with the hollow portion of the housing 16. Further, below the spin motor 3, a gas supply section 19 is provided with a supply gas temperature adjustment mechanism that operates in conjunction with the gas supply section IO. Further, the gas 11 sent out from the gas supply section 19 is supplied into the housing 16 via the gas supply pipe 20, and is supplied into the processing chamber 7 on the lower surface side of the wafer 1 from the gas supply port 18. Gas supply part 1
0 and the gas 11 sent out from the gas supply section 19 are controlled to the same temperature. Further, the temperature of the gas 11 is set to be lower than the saturated vapor pressure temperature of the photoresist liquid 15. As a result, when the spin chuck 2 is rotated by the spin motor 3 at a predetermined rotation speed and the photoresist liquid 15 dropped onto the main surface of the wafer 1 is spread over the entire main surface of the wafer 1 using centrifugal force, the gas 11 is adjusted to a temperature below the saturated vapor pressure of the photoresist liquid 15, the photoresist liquid 15
Since the photoresist liquid 15 does not leak out when it spreads, the photoresist liquid 15 spreads over the entire main surface of the wafer 1 with a uniform thickness.

Further, the periphery of the processing chamber 7, that is, the pair of proximity plates 5
．． A ring-shaped anti-rebound tube 21 is provided on the periphery of the holder 6 and extends along the periphery. An exhaust pipe 23 extending to an exhaust section 22 is connected to this anti-rebound cylinder 21 in a communicating state. Further, air intake holes 24 are provided at the opposite side of the part of the anti-rebound cylinder 21 that communicates with the exhaust pipe 23 . The exhaust mechanism includes the exhaust section 22. Anti-rebound cylinder 21° Exhaust pipe 23. Intake hole 24. It takes in air 25 from the intake hole 24 and exhausts it. As a result, the exhaust section 22
Due to the exhaust operation, the air 25 sucked in from the intake hole 24 is exhausted through the exhaust pipe 23, and since the exhaust mechanism itself constitutes an exhaust flow, the ejecting action causes the air 25 to contain the photoresist droplets in the processing chamber 7. suck out the gas,
It is designed to perform forced exhaust.

It should be noted that the opening interval at the periphery of the processing chamber 7, that is, the spacing between the openings at the periphery of the processing chamber 7, which is constituted by a pair of proximity plates 5 and 6, and the rebound prevention cylinder 2
1, the communication part between the anti-rebound tube 21 and the exhaust vibrator 23 is configured to have a much wider gap, so that the photoresist droplets, etc. that have once entered the anti-recoil tube 21 are trapped inside the processing chamber 7. It is designed not to revert to.

To prevent the photoresist droplets from returning to the processing chamber 7, the air 25 sucked in from the air intake hole 24 also acts. That is, the intake holes 24 are arranged at regular intervals in the anti-rebound tube 21, and as a result of forced exhaust from the exhaust section 22, the air 25 is guided into the apparatus in synchronization with the exhaust from the processing chamber 7, and as a result, the exhaust volume is balanced. remains constant. Furthermore, due to the existence of the intake hole 24, the air 25 flowing in from the intake hole 24 flows toward the exhaust part 22, so that the gas in the processing chamber 7 is bounced back due to the suction effect of the gas, that is, the ejection effect. It is sucked out into the prevention cylinder 21. Therefore, the phenomenon of backflow of photoresist droplets in the anti-rebound cylinder 2I into the processing chamber 7 is less likely to occur, and the scattered photoresist droplets do not re-adhere to the wafer 1.

Now, to explain the structure of the proximity plate 5.6 and the anti-rebound tube 21, the position of the proximity plate 5 is
When the photoresist liquid 15 is dropped onto the wafer 1 and the wafer 1 is rotated by the spin motor 3 to form a photoresist film, the photoresist liquid droplets scattered from the wafer 1 are not attached, and the vortex generated by the rotation of the wafer 1 is This is a position where no stagnation area occurs. Further, the inner surface shape of the proximity plate 5 is determined by the temperature conditions of the gas 11 supplied onto the wafer 1.
It is determined by the vapor pressure conditions of the solvent such as photoresist liquid, etc.

In an experimental example by the present inventor, the radial end face dimensions of the wafer 1 and the proximal plate 50 were made approximately equal, and the gap between the wafer 1 and the proximal plate 5 at the end was maintained at approximately 5 mm.
By configuring q to have a spread angle of about 140° at the center, results have been obtained in which the accuracy of the photoresist film thickness can be improved and the number of rebound photoresist particles adhering to the wafer 1 can be reduced.

In this experiment, the temperature of the gas 11 to be supplied was set to about 10
The process was carried out at a low temperature below the saturated oven pressure of the photoresist solution to obtain a uniform film thickness.

Regarding the proximal plate 6, as described above, in order to prevent a stagnation area from occurring in the space between the proximal plate 6 and the wafer 1 when the wafer 1 is rotated, a predetermined amount of gas 11 is supplied from the gas supply section 19.
is supplied.

Although not shown, this device is entirely controlled by a control system. In other words, the rotation speed of the spin chuck 2, the processing time, the temperature and supply amount of the gas 11, the exhaust section, etc. 22 displacement etc. are automatically controlled. Further, a series of sequential operations are similarly automatically controlled by this control system.

Next, a method for forming a photoresist film with a uniform thickness on the main surface of the wafer will be described.

First, the information shown below is input to the control system.

(1) Setting the temperature value of the gas 11 supplied from the gas supply section 10, the solvent vapor pressure value (solvent concentration), and the solvent supply amount.

(2) Setting the temperature value of the gas 11 supplied from the gas supply section 19, the solvent vapor pressure value (solvent concentration), and the solvent supply amount.

(3) Setting the amount of exhaust gas exhausted from the exhaust section 22.

(4) Setting the temperature and amount of the photoresist liquid 15 dropped per drop from the photoresist supply unit 13.

(5) Setting the rotation speed of the spin motor 3.

(6) Setting a series of sequence operations.

After setting the processing conditions as described above, when the apparatus is started, the wafer 1 is loaded onto the spin chuck 2 by a handler (not shown).

The wafer 1 is held on the spin chuck 2 by vacuum suction.

Next, a gas 11 controlled under predetermined conditions is introduced into the processing chamber 7.
is supplied.

On the other hand, the exhaust section 22 uniformly exhausts a predetermined amount of air from the rebound prevention cylinder 21. Under this condition, the spin motor 3 is driven and the wafer 1 is rotated at a predetermined speed. Furthermore, a predetermined amount of photoresist liquid 15 is dropped onto the center of the main surface of the rotating wafer 1 by the operation of the photoresist supply section 13. Since the wafer 1 is rotating at high speed, this photoresist liquid 15 instantly spreads over the entire main surface of the wafer 1. Further, when applying the photoresist liquid 15, the application is performed at a low temperature of about 10'. As a result, since the photoresist liquid 15 does not smoke and the wafer I rotates at high speed, the photoresist liquid 5 spreads to a uniform thickness over the entire main surface of the wafer 1. Gas 11 is constantly supplied to the processing chamber 7 on the front and back sides of the wafer 1, and the gas 11 in the parentheses flows along the front and back surfaces of the wafer 1 in a laminar flow and is forced into the anti-rebound cylinder 22. Since the photoresist droplets scattered from the wafer 1 are exhausted through the wafer 1, the photoresist droplets do not adhere to the surface of the wafer 1 again (
Clean photoresist coating without foreign matter adhesion can be achieved.

Note that the exhaust gas 26 such as photoresist droplets that has entered the anti-rebound cylinder 21 does not return to the processing chamber 7 due to the forced exhaust of the exhaust system or the ejector effect, thereby preventing foreign matter from adhering to the wafer 1. The effect is also certain.

After the photoresist application operation, the spin chuck 2 stops rotating, and the wafer 1 on the spin chuck 2 is moved by the handler.
is unloaded into a predetermined portion.

According to such an embodiment, the following effects can be obtained.

(1) According to the present invention, the airflow velocity acting on the surface of the workpiece can be controlled to a constant, arbitrary optimum value depending on the coating material and the coating film thickness to be formed, which improves reproducibility (uniform thickness). The effect is that a thin film can be formed.

(2) According to the present invention, since the temperature value of the airflow acting on the object to be treated can be precisely controlled to any value, a low temperature state that reduces the amount of evaporation of the solvent contained in the coating material, that is, the solvent vapor pressure Since the coating process can be carried out in a state in which the thickness of the coating can be reduced, it is possible to achieve the effect of forming a film with a uniform thickness with less striae.

(Button) According to (1) and (2) above, according to the present invention,
The enviable effect of being able to provide a coating device with high film formation accuracy can be obtained.

(4) According to the above (1), according to the present invention, the air velocity distribution state in the processing chamber is not changed, a constant amount of gas flow is formed in the upper and lower spatial regions of the object to be processed, and the object to be processed is The effect described in (1) above is achieved because the rotating airflow and the scattered coating material generated when the pipe rotates are blocked from acting on the processing space of the adjacent plate pipes, and the airflow condition between the adjacent plates is maintained constant. In addition, it is possible to form a highly pure and homogeneous film without causing the scattered photoresist solution generated during spin coating to re-adhere to the object to be processed.

(5) According to the present invention, since the communication gap between the anti-rebound tube and the exhaust pipe is wider than the communication gap between the processing chamber and the anti-rebound tube, exhaust gas from the processing chamber into the anti-rebound tube is Since it is difficult for the photoresist droplets to return into the processing chamber, the effect that coating can be achieved without causing foreign matter to adhere to the wafer can be obtained.

(6) According to the present invention, the exhaust system on the side of the anti-rebound tube has a structure in which air from outside the device is sucked in through the intake hole provided in the anti-rebound tube, and this air is also exhausted. This air flow also has the effect of sucking out the gas in the processing chamber, allowing efficient exhaust, and the structure prevents the exhaust gas from returning to the processing chamber from the rebound prevention cylinder, so the processing chamber is not recontaminated. The effect is that coating can be accomplished without causing foreign matter to adhere to the wafer.

(7) According to the above (1) to (6), according to the present invention, it is possible to achieve the effect that fine patterning of semiconductor devices can be achieved by improving coating accuracy.

(8) According to the above (1) to (6), according to the present invention, it is possible to achieve the effect that the yield of fine patterning of semiconductor devices can be improved by reducing the adhesion of foreign substances.

(9) According to the above (1) to (8), according to the present invention, a synergistic effect can be obtained in that semiconductor devices of excellent quality can be provided at low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. For example, the exhaust resistance may be sequentially changed according to the arrangement of the exhaust pipes 23 as a means for maintaining an equal balance of the amount of exhaust gas exhausted from the processing chamber constituted by the adjacent plates. That is, the gap on the side of the processing chamber near the exhaust vibrator 23 position is made smaller, the gap on the side farther from the exhaust vibrator 123 position is made larger, the exhaust resistance is adjusted, and the exhaust volume balance is maintained evenly. Further, the coating material may be something other than photoresist, such as spin-on glass.

Even with polymide resin, impurity diffusion materials, etc., the same effects as in the above embodiments can be obtained.

The above explanation has mainly been about the application of the invention made by the present inventor to photoresist coating technology, which is the background field of application, but the invention is not limited thereto. It can also be applied to techniques for applying coating materials to metal plates and the like. Furthermore, the present invention can be applied to coating techniques in the photographic industry, printing industry, precision machinery industry, chemical industry, etc. in addition to the semiconductor industry.

The present invention is applicable at least to coating technology.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, in the coating apparatus of the present invention, a wafer, which is an object to be processed, is placed on the rotating spin chuck, and the proximity plate is arranged at a position where the coating liquid scattered by the centrifugal force at the upper and lower parts of the rotating spin chuck directly reaches and is not reflected. The structure is such that clean gas is forcibly supplied from the center of the proximal plate.

Furthermore, an exhaust mechanism is installed around the periphery of the processing chamber formed by the pair of proximal plates, which uses an ejector action to forcefully exhaust the gas within the processing chamber. The photoresist can be applied to a uniform thickness because it is evacuated in a laminar flow without creating a layer of heat. In addition, since the photoresist liquid splashed from the wafer edge is forcibly exhausted by the laminar gas flow, the photoresist particles do not return to the processing chamber again, and the photoresist can be applied without foreign matter adhering to the wafer. It can be achieved. Furthermore, if the temperature of the supply gas is adjusted and coating is performed at a temperature below the saturated vapor pressure of the photoresist, the photoresist on the main surface of the wafer will be difficult to evaporate and the thickness will not vary due to evaporation. Since the H'J thickness is determined only by wafer rotation, a photoresist film with a uniform thickness can be obtained.

[Brief explanation of the drawing]

The drawing is a sectional view showing essential parts of a coating device according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A spin chuck that rotates with a workpiece placed on the top surface, a coating liquid supply mechanism that supplies a coating liquid to the workpiece on the spin chuck, and an upper part of the spin chuck and a gas supply mechanism that supplies clean gas to the central upper and lower parts of the spin chuck; and an exhaust mechanism provided along the periphery of the processing chamber configured by the pair of proximity plates. A coating device comprising: 2. The coating apparatus according to claim 1, wherein the gas supply mechanism is capable of adjusting the temperature of the supplied gas.