JPH07135154A - Method and device of baking photoresist film - Google Patents

Abstract

PURPOSE:To suppress the sticking of photomasks to wafers by a method wherein the surface of photoresist films are dried after workpiece coated with the photoresist films are heated from rear surface side to be baked. CONSTITUTION:The wafers 4 coated with photoresist films 5 are heated from rear surface side on a plurality of hot plate heaters 3 so as to evaporate the solvent in the photoresist films. At this time, a far infrared radiation heater 6 is arranged on the above position of the outermost side hot plate heater 3 so that the water 4 on the outermost side hot plate heater 3 may be heated from rear surface side simultaneously the surface of the photoresist film 5 may be radiated from the far infrared radiation heater 6 to accelerate the drying up of the surface of the photoresist films 5 for setting the same. Through these procedures, even if photomasks are made closely adhere to the photoresist films 5 on the wafers 4 in the next contact exposure step, the sticking phenomenon of the photomasks to wafers 4 can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for baking a photoresist film in a lithographic process, which is effective when used for baking a photoresist film coated on a wafer in a semiconductor device manufacturing process. Regarding technology.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a photoetching technique is used to form a pattern on a wafer. This photoetching technique is basically carried out as follows. That is, while applying a photoresist film on a semiconductor wafer and baking the photoresist film, the photoresist film is exposed by irradiating the photoresist film with ultraviolet light passing through a photomask to form a desired pattern. . Then, the exposed portion or unexposed portion of the photoresist film is melted by a developing solution to develop the photoresist film and leave a required photoresist pattern on the wafer. After baking the photoresist pattern, the film under the resist is etched using the photoresist pattern on the wafer as a mask.

In the above, the coating process to the baking process, or the developing process to the baking process are usually carried out by an integrated processing apparatus.

As the exposure method, one of a contact exposure method, a projection method and a step-and-repeat method is used, but the most suitable method is adopted in consideration of the minimum processing size, throughput and the like.

As an example in which the photoresist processing technique is described, "Electronic Materials 198" issued by Kogyo Kenkyukai Co., Ltd.
November, 4 issue, separate volume, issued November 20, 1984, P6
7 to P71.

[0006]

Generally, among the exposure methods, the contact exposure method has an advantage of high throughput, but has a drawback that the minimum processing size cannot be reduced.
Further, since the exposure is performed by bringing the wafer and the mask into contact with each other at the time of exposure, it has a drawback that a foreign substance is likely to be generated and a phenomenon called sticking in which the wafer and the mask are not separated from each other is easily generated.

In particular, when sticking occurs, the exposure apparatus must be stopped and the wafer and the mask must be manually peeled off, which significantly reduces the operation rate of the apparatus. In addition, since the wafer and the mask on which the sticking has occurred are scratched, there is a problem that the yield is reduced.

An object of the present invention is to provide a baking treatment technique for a photoresist film which can suppress the occurrence of sticking.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0010]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, the surface of the photoresist film is dried at the end or after the baking process, which is performed by heating the object to which the photoresist film is applied from the back surface side.

[0012]

The surface of the photoresist film is sufficiently dried because the surface of the photoresist film in which the solvent is likely to remain in the baking process performed by heating from the back side of the object to be processed is dried at the end of the baking process or after the completion of the process. .
Therefore, even if the mask is brought into close contact with the photoresist film on the wafer in the contact exposure step, the occurrence of sticking can be suppressed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cut front view showing a baking processing apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view for explaining a wafer transfer feeder.

The baking processing apparatus 1 in this embodiment is equipped with a baking furnace 2, and four hot plate heaters 3 are installed in the baking furnace 2 along the wafer 4 transfer line. Each hot plate heater 3 has a heater built in a main body formed in a disk shape having a diameter substantially equal to that of the wafer 4, and the back surface of the wafer 4 is uniformly heated by heat conduction to form a photoresist film on the wafer 4. 5 is configured to be baked.

A far-infrared heater 6 is installed directly above the hot plate heater 3 on the most exit side of these hot plate heaters 3 and uniformly heats the photoresist film 5 on the wafer 4 from above. Photoresist film 5
The surface of the substrate can be baked.

A thermocouple temperature sensor 7 is arranged between the far infrared heater 6 and the hot plate heater 3, and the temperature sensor 7 detects the temperature at the position above the hot plate heater 3 and detects the detected temperature. Is a far infrared heater 6
It is configured to be sent to the temperature controller 8 arranged at the upper position of the. The temperature controller 8 is configured to control the temperature of the far-infrared heater 6 according to the detected temperature, and the temperature for heating the surface of the photoresist film 5 is equal to or lower than the glass transition temperature of the photoresist film 5 and the surface of the photoresist film 5. To maintain the temperature above the temperature at which the solvent on the surface of the photoresist film 5 evaporates.

An upper portion of the baking furnace 2 is covered with a cover 9. Inside the cover 9, an exhaust pipe 1 for discharging gas released from the photoresist film 5 during the baking process.
0 is installed. In addition, a mechanism (not shown) for supplying gas into the baking furnace 2 is provided in the baking furnace 2 in order to keep the inside of the baking furnace 2 at a positive pressure and prevent entrainment of the atmosphere.

A wafer receiving stage 11 is installed in front of the entrance of the baking oven 2, and a wafer delivery stage 12 is installed after the exit of the baking oven 2.

The transfer of the wafer 4 is carried out by the transfer feeder 13. The transport feeder 13 extends along the transport line in which the hot plate heater 3 is arranged, and as shown in FIG. 2, a pair of feeder main bodies 13a extending along the transport line, and both feeders. Body 13
a, 13a, and a plurality of sets of wafer holding members 13b that face each other and are arranged at a pitch of the hot plate heater 3 groups in the length direction to hold the back surface of the wafer 4 from both sides.

Each wafer holding member 13b is composed of a fork-shaped arm projecting from each of the pair of feeder main bodies 13a, and each wafer holding member 13 is arranged to face each hot plate heater 3.
Each pair of arms b has an escape groove 14 formed therein at a position facing each other at the peripheral end. Transport feeder 13
Is operated by the transport feeder driving unit 15 so as to draw a rectangular trajectory in a vertical plane.

The operation of the transport feeder 13 will be specifically described below. The carrying operation is repeatedly performed with the following cycle as one unit. That is, first, after the wafer presence / absence detection mechanism (not shown) confirms that the wafer 4 on the wafer delivery stage 12 has been delivered to a post-process unit (not shown), for example, an unloader, it is preset. When the baking processing time has ended, the transport feeder 1
3 moves horizontally to the wafer receiving stage 11 side.

After the movement is completed, the carrier feeder 13 starts to move upward, and simultaneously lifts the wafer receiving stage 11 and the wafer 4 on each hot plate heater 3. After the ascent is completed, the transfer feeder 13 horizontally moves to the wafer payout stage 12 side with the wafer 4 still mounted.

After completion of the movement, the feeding feeder 13 descends,
Each wafer 4 is placed on the adjacent hot plate heater 3 and wafer delivery stage 12. After the end of the descent, it waits until the baking processing time ends.

Next, the operation of the baking processing apparatus 1 will be described. In the photoresist coating integrated processing apparatus, the baking processing apparatus 1 is installed after the coating apparatus, and the wafer is continuously processed from the coating step to the baking processing.

The wafer 4 is coated with a photoresist film 5 on the wafer 4 in a coating step. That is, the wafer 4 is rotated in the coating process, and the photoresist is dropped on the center of the rotating wafer 4. Then, the photoresist is diffused in the radial direction by the centrifugal force and is evenly spread over the entire surface of the wafer 4, so that the photoresist film 5 is uniformly formed on the surface of the wafer 4.

The wafer 4 coated with the photoresist film 5 is moved to the wafer receiving stage 11 in the next baking processing apparatus 1, and is further transferred onto the hot plate heater 3 in the baking furnace 2 by the transfer feeder 13 and The photoresist film 5 is baked.
The wafer 4 is usually heated at a temperature of around 100 ° C. for several minutes to perform a baking process.

That is, the wafer 4 on which the photoresist film 5 has been applied is heated from the back surface side on the four hot plate heaters 3 to be heated, and the solvent in the photoresist film 5 is evaporated. At this time, the solvent in the photoresist film 5 moves from the wafer 4 side of the photoresist film 5 to the surface side, and evaporates from the interface between the photoresist film 5 and the atmosphere, so that the solvent concentration distribution in the photoresist film 5 is on the wafer 4 side. It may be low, the surface side may be high, and the solvent on the surface side of the photoresist film 5 may remain. In that case, since the surface of the photoresist film 5 is soft, if the photomask is brought into close contact with the photoresist film 5 of the wafer 4 in the next contact exposure process, sticking may occur between the photoresist and the wafer 4. .

However, in this embodiment, the far infrared heater 6 is provided above the hot plate heater 3 on the most outlet side, and the wafer 4 on the hot plate heater 3 on the most outlet side is transferred from the back surface side. At the same time as the heating, the surface of the photoresist film 5 is also radiantly heated, so that the drying of the surface of the photoresist film 5 is promoted and the surface becomes hard. As a result, in the contact exposure step in the next step,
Even if the photomask is brought into close contact with the photoresist film 5 on the wafer 4, the occurrence of sticking between the photomast and the wafer 4 can be suppressed.

In the above, the reason why the surface of the photoresist film 5 on the wafer 4 is not dried from the beginning of the baking process is that the surface of the photoresist film 5 is heated to dry the surface of the photoresist film 5 from the beginning of the baking process. And the solvent in the photoresist film 5 becomes less likely to evaporate,
This is because the baking effect is weakened.

According to the embodiment described above, the following effects can be obtained. By providing the far-infrared heater 6 for heating the surface of the photoresist film 5 at the end of the baking process, the surface of the photoresist film 5 where the solvent is likely to remain in the baking process for heating from the back surface of the wafer 4 is sufficiently dried. Therefore, even if the photomask and the photoresist film 5 on the wafer 4 are brought into close contact with each other in the contact exposure step in the next step, the occurrence of sticking between the photomask and the wafer 4 can be suppressed.

As described above, since the occurrence of sticking is prevented in advance, it is possible to prevent the operating rate of the exposure apparatus from decreasing. In addition, defects caused by scratches that occur when the photomask and the wafer 4 are peeled off during sticking are eliminated, and the yield can be improved. Further, it is not necessary to discard a defective photomask and purchase a new mask, so that the cost can be reduced.

By controlling the temperature of the far-infrared heater 6 for drying the surface of the photoresist film 5 by the thermocouple temperature sensor 7 and the temperature controller 8, the surface of the photoresist film 5 is not deteriorated and can be dried well. It will be possible.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the means for drying the surface of the photoresist film 5 is not limited to the far infrared heater, and hot air may be applied to the surface of the photoresist film 5 by a hot air heater.

The means for drying the surface of the photoresist film 5 is not limited to the heating means by the far infrared heater or the hot air heater, and the surface of the photoresist film 5 is dried by applying dry air or an inert gas. You may do it.

Further, the time for drying the surface of the photoresist film 5 is not limited to the end of the baking process, but may be performed after the baking process and before the contact exposure process. In this case, for example, it may be placed in an oven or the like and dried by a batch process.

In the above description, the case where the invention made by the present inventor is mainly applied to the technique of baking the photoresist film coated on the wafer in the manufacturing process of the semiconductor device which is the field of application of the invention will be described. However, the present invention is not limited thereto, and can be applied to general baking processing of a photoresist film in lithography processing, such as a baking processing technique of a photoresist film in manufacturing a photomask or a liquid crystal panel.

[0038]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

The surface of the photoresist film is dried at the end of or after the baking process, which is performed by heating the object to which the photoresist film is applied from the back side, to dry the surface of the photoresist film in the contact exposure process. It is possible to prevent the occurrence of sticking between the photomask and the wafer when the photoresist film is adhered.

[Brief description of drawings]

FIG. 1 is a partially cut front view showing a baking processing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view for explaining a wafer transfer feeder.

[Explanation of symbols]

1 ... Baking treatment device, 2 ... Baking furnace, 3 ... Hot plate heater, 4 ... Wafer, 5 ... Photoresist film,
6 ... Far infrared heater, 7 ... Thermocouple temperature sensor, 8 ... Temperature controller, 9 ... Cover, 10 ... Exhaust pipe, 11 ... Wafer receiving stage, 12 ... Wafer delivery stage, 13
... transport feeder, 13a ... feeder main body, 13b ... wafer holding member, 14 ... escape groove, 15 ... transport feeder drive unit.

Claims (4)

[Claims] 1. A method for baking a photoresist film, which comprises drying the surface of the photoresist film at the end or after the baking treatment step in which the object to be treated coated with the photoresist film is heated from the back surface side. . 2. The method of baking a photoresist film according to claim 1, wherein the surface of the photoresist film is dried by heating. 3. The method of baking a photoresist film according to claim 1, wherein the surface of the photoresist film is dried by using gas. 4. A baking treatment means for heating the back surface of an object to be processed coated with a photoresist film, and a means for drying the surface of the photoresist film of the object to be processed at the end of or after the baking step. A baking device for a photoresist film, which is characterized in that