JPH04190873A - Coating device - Google Patents

Abstract

PURPOSE:To prevent a coating liq. from being mixed with air bubbles and permit an appropriate amt. of the coating liq. to be replenished as required by a method wherein the existence of the bubbles mixed in the coating liq. being sent from a receiving container to a transparent pipe can be detected by a sensor. CONSTITUTION:A gas is sent pressurized from a nitrogen gas supply system 26 to a receiving container 24 contg. a coating liq. 23 therein to send out the coating liq. 23 from a pipe 16. The pipe 16 is at least partially provided with a transparent pipe 27 formed of a transparent body, whereby the existence of the bubbles 31 mixed in the coating liq. 23 being sent from a receiving container 34 to the transparent pipe 27 is detected by a sensor 30 consisting of a light emitting element 28 and a light receiving element 29. As a result, this method prevents the coating liq. from being mixed with the air bubbles and permits an appropriate amt. of the coating liq. to be replenished as required.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a coating device.

[Prior Art] Generally, in the process of forming a pattern on a thin film stacked on a semiconductor wafer in semiconductor manufacturing, a resist is applied to a semiconductor wafer, exposed through a mask formed in a pattern, developed, and etched. The thin film is formed into a pattern. A resist coating device or a developing device used for resist coating or development drops a certain amount of resist solution or developer stored in a storage container from a nozzle onto a semiconductor wafer that is vacuum-adsorbed onto a chuck. By rotating at high speed, the resist or developer dropped onto the semiconductor wafer is uniformly applied over the entire surface.

[Problems to be Solved by the Invention] However, as integrated circuits become extremely highly integrated, coating unevenness becomes a significant influence. In some cases, uneven coating is caused by air bubbles contained in a high-clay resist solution or developer solution, and it is difficult to remove air bubbles once they have been mixed in, so efforts are being made to remove the air bubbles. Especially the third
As shown in the figure, a gas such as nitrogen gas is supplied to the pipe 4 to send the resist solution or developer 2 from the storage container 1 to the pipe 3.
Since the resist solution or the developer 2 remaining in the storage container 1 becomes low, air bubbles get mixed in and sag. Therefore, a tank 5 is provided in the piping 3, and the liquid level in the tank 5 is detected by a liquid level sensor 6, etc., and the remaining amount of resist solution or developer in the storage container 1 is detected to prevent air bubbles from flowing out to the nozzle. Was.

However, when the remaining amount is low, air bubbles that may otherwise be mixed in are not detected, and the coating film applied to the semiconductor wafer often becomes non-uniform. As a result, the yield of the product deteriorated.

The present invention has been made to solve the above-mentioned drawbacks, and is capable of detecting a small amount of liquid remaining in a storage container for a coating liquid that is fed under pressure with gas and supplied to piping. An object of the present invention is to provide a coating device that can immediately detect air bubbles even if they are mixed in, and improve the yield of products.

[Means for Solving the Problems] In order to achieve the above object, the coating device of the present invention is a coating device that sends out the coating liquid from a pipe by pumping gas into a storage container in which the coating liquid is stored. At least a portion of the piping includes a transparent tube made of a transparent body,
The apparatus is equipped with a sensor that detects the presence of bubbles mixed into the coating liquid sent from the storage container to the transparent tube.

[Function] At least a part of the piping of the coating device is made of a transparent tube, which sends the liquid out of the storage container through the piping connected to the storage container by injecting gas into the coating liquid stored in the storage container. Form. A sensor such as a light emitting/receiving element is provided in this transparent tube. When air bubbles of a certain size are present in the piping, the amount of light incident on the light receiving element changes due to the air bubbles, so the presence or absence of air bubbles can be detected. When air bubbles are detected, it can be known that the remaining amount of liquid in the storage container is small, and therefore a constant amount of liquid without air bubbles can be supplied to the storage container at all times.

[Example] An example in which the coating apparatus of the present invention is applied to a resist coating apparatus for a semiconductor manufacturing process will be described with reference to the drawings.

The resist coating device 7 shown in FIG. 1 mounts and fixes a wafer 8 by vacuum suction or the like, and includes a chuck 10 having a disc-shaped upper surface and fixed to a rotating shaft of a motor. A discharge nozzle 11 is provided above the chuck 10 and connected to a horizontal movement mechanism, and can be retracted from above the chuck 10 to a position outside the wafer 8 in order to perform dummy dispensing.

A cup 12 is provided around the chuck 10 so as to surround the chuck 10, and in order to spread the resist dropped onto the wafer 8 from the discharge nozzle 11 over the entire surface of the wafer 8.
When the chuck 10 is rotated, excess resist is prevented from scattering around the periphery of the wafer 8. moreover,
Below the cup 12, in order to prevent the resist that has bounced off the cup 12 from adhering to the wafer 8 again, there is an exhaust port connected to an exhaust device (not shown) to form a gas flow downwards in the cup 12. is provided.

Further, the cup 12 is provided with a vertical movement mechanism (not shown) so as to be lowered from the position shown in the figure to facilitate loading/unloading of the wafer 8 when the cup 12 is loaded/unloaded onto the wafer 8 and the chuck 10 by a transport mechanism (not shown). In order to prevent the resist remaining in the discharge nozzle 11 from dripping after dropping the resist, the discharge nozzle 11 is driven by a suckback valve 13 for suctioning the remaining resist, and an air cylinder 14 for discharging a certain amount of resist liquid. A bellows pump 15, a water jacket 17 for temperature adjustment to warm the piping 16 to an appropriate temperature, a filter 20, a valve 21, a liquid detection device 22, etc. connected to the deaerator 19 via the valve 18, etc. The resist liquid 23 is connected to a container 24 containing a liquid resist liquid 23 .

A nitrogen gas supply system 26, which is a gas, is connected to the resist liquid storage container 24 via a pipe 25.

As shown in FIG. 2, a transparent tube 27, at least a portion of which is made of a transparent material, is inserted into the storage container 23 of the resist coating device 7 as described above. The liquid detection device 22 provided in the transparent tube 27 includes a light emitting element 28 and a light receiving element 29.
A sensor 30 is provided. As shown in the figure, the structure is not limited to the transmissive type, but may be a reflective type in which the transmitting and receiving elements 28 and 29 are provided in the same part. Due to the presence of air bubbles 31 mixed in the resist liquid 23, the light emitted from the light projecting element 28 changes the amount of light incident on the light receiving element 29 because the air bubbles 31 function as a lens. For example, if the inner diameter of the transparent pipe 27 is 4 mm, the air bubble 31 is 1 m long.
It is possible to detect objects down to mm. Liquid detection device 22
further includes a CPU that outputs a detection signal when the sensor 30 compares the input value from the light receiving element 29 with predetermined information and detects the presence of bubbles 31, and generates an alarm sound by an alarm sound generation signal from the CPU. A warning sound generating device 32 is provided to make a sound.

The operation of the resist coating device 7 configured as above will be explained.

The cup 12 is lowered from the position shown in the figure, and the wafer 8 is carried onto the chuck 10 by a transport mechanism (not shown). The cup 12 rises to the position shown in the figure and becomes ready for application. The discharge nozzle 11 is moved above the center of the wafer 8 by a horizontal movement mechanism to supply resist liquid. A piping 25 is inserted into the storage container 24 for the resist liquid 23 from the nitrogen gas supply system 26, and nitrogen gas is forced into the storage container 24 from the piping 25. The resist liquid 23 is pumped from the storage container 24 into the transparent tube 27 . At this time, if a sufficient amount of the resist liquid 23 is secured in the storage container 24, the air bubbles 31 will be removed from the resist liquid 23.
3, the resist solution is delivered without being mixed in. If no air bubbles 31 are detected by the sensor 30, the resist liquid 23 continues to be delivered to the transparent tube 27. and valve 21
, is heated to an appropriate temperature by the water jacket 17 via the filter 20, and is supplied to the bellows pump 15. Particles contained in the resist or very small air bubbles not detected by the sensor 30 are filtered by the filter 20 and removed by the degassing device 19. Bellows pump 1
A predetermined amount of the resist liquid 23 supplied to the resist liquid 23 is delivered to the piping 16 by a bellows pump 15 driven by an air cylinder 14, and is dripped onto the wafer 8 on the chuck 10 from the discharge nozzle 11. Thereafter, the resist liquid remaining without being dropped into the discharge nozzle 11 is sucked by the suckback valve 13 to prevent the liquid from dripping onto the wafer 8. Then, the chuck 10 is rotated at high speed by the motor 9, and the resist is applied. After the coating is completed, the cup 12 is lowered, the wafer 8 is loaded and unloaded, and the above steps are repeated. Then, the resist liquid 23 in the storage container 24 is consumed,
When the amount remaining becomes small and bubbles 31 are generated in the transparent tube 27, the light receiving element 21 receives the light emitted from the light projecting element 28.
The amount of light incident on the sensor 30 changes, and the sensor 30 sends a bubble detection signal to the CPU. The CPIJ outputs a warning sound generation signal to the warning sound generating device 32, and the warning sound is sounded.

Thereby, the operator can open the storage container 14 for the resist liquid 23.
Knowing that the amount remaining in the resist liquid 23 is small, the valve 21 is closed and the storage container 24 is filled with the resist liquid 23. and valve 2
1 is opened, air flowing into the pipe is removed by a deaerator 19 connected to the filter 20, and resist coating is restarted. In addition to this air bubble detection, a color filter may be provided or a contrast may be added to the photoelectric detection of the transparent tube 27 as appropriate.

According to the present invention, since bubbles could not be detected conventionally,
Instead of the operator having to visually check, the work efficiency can be greatly improved because the operator is notified by the detection means, and the resist solution containing air bubbles is applied to the wafer, resulting in uneven coating and yield. It has become possible to rule out that this is a bad thing.

The above description is one embodiment of the coating device of the present invention, and the present invention is limited to a resist coating device.It can be applied to any coating solution supplied from a storage container, for example, to coating a developer, etc. It can also be applied to liquids with high viscosity that are difficult to remove when air bubbles are mixed in. Furthermore, it can be applied to LCD boards, printed circuit boards, etc.

[Effects of the Invention] As is clear from the above description, according to the coating device of the present invention, when supplying the coating liquid in the storage container by pressurizing gas, air bubbles mixed into the coating liquid can be detected. Since the operator is provided with means for detecting that the remaining amount is low, it is possible to prevent air bubbles from being mixed into the coating liquid and to appropriately replenish the amount of liquid as necessary.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment to which the coating device of the present invention is applied, FIG. 2 is a diagram showing main parts of the embodiment shown in FIG. 1,
FIG. 3 is a diagram showing a conventional example. 16... Piping 22... Liquid detection device 23... Resist liquid (gas) 24... Storage container 26... Nitrogen gas supply system (Gas) 27...
...Transparent tube 30...Sensor agent Patent attorney Moritani Figure 1! 12rI! J

Claims (1)

[Claims] A coating device that sends out the coating liquid from a pipe by force-feeding gas to a storage container in which the coating liquid is stored, wherein at least a part of the piping includes a transparent tube made of a transparent body, A coating device comprising a sensor that detects the presence of bubbles mixed into the coating liquid delivered to a transparent tube.