JPH04355922A - Polyimide hardening device - Google Patents

Abstract

PURPOSE:To reduce the number of washes of the main body of a heating furnace, a gas introducing pipe, a board-retainer and the like, to reduce the readhesion of reaction product gas to a substrate, and the frequency of cleaning in an exhaust system is made almost constant. CONSTITUTION:An introducing hole, where carrier gas is introduced into a furnace, is perforated at the upper wall part of the main body 1 of a heating furnace. A water-cooling trap 11, which is opened at the lower part of the heating furnace main body and used to exhaust the liquefied reaction product gas to the downstream side of a sideway-facing exhaust pipe 9 extending toward outside direction from the exhaust hole, is provided. A subheater 12A, with which the lower part of the furnace is heated up, is provided on the outer circumference of the lower part of the wall section of the heating furnace main body 1, and a second substrate 12B, with which the pipe 9 is heated up, is provided on the outer circumference of the sideways exhaust pipe 9. An autodamper 14, with which exhaust pressure can be practically maintained constant, is provided on the downstream side of the water-cooling trap 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide curing apparatus for heating and curing polyimide on a substrate.

0002

2. Description of the Related Art In recent years, photosensitive polyimide, which is an organic material, has been increasingly used as a final protective film for semiconductor devices or as an alignment film for liquid crystals. The reason for this is that compared to conventional polyimide, photosensitive polyimide can form a pattern on a substrate in the same manner as photoresist, so the pattern formation process can be simplified.

In this case, a polyimide curing apparatus as shown in FIG. 2 has conventionally been used as an apparatus for heating and curing the photosensitive polyimide patterned on the substrate.

This polyimide curing apparatus includes a heating furnace main body 1 equipped with a main heater 4 for heating and curing polyimide on a substrate, and a shelf housed in the heating furnace main body 1 for holding a substrate coated with polyimide. a shaped board jig 5;
A board support member 17 that holds the board jig 5, a gas introduction pipe 16 that opens inside the heating furnace main body 1 and introduces carrier gas into the furnace, and a gas introduction pipe 16 that opens at the bottom of the heating furnace main body 1 and introduces the carrier gas into the furnace. In order to discharge the generated reaction gas together with the carrier gas to the outside of the furnace, a main exhaust pipe 13 is provided which extends from the exhaust port 3 at the lower part of the heating furnace main body 1 to the outside of the furnace and upwardly.

[0005]

[Problems to be Solved by the Invention] However, in the polyimide curing apparatus having the above structure, the reaction product gas (outgas) generated when polyimide is cured is absorbed into the lower temperature part of the heating furnace body 1, that is, the heating furnace. Main body 1
15, the vicinity of the lower end opening 10 of the heating furnace body 1, and the lower part of the gas introduction pipe 16. There was a problem in that the support member 17 had to be cleaned.

[0006] Furthermore, there is a correlation between the amount of reaction product gas adhering to the heating furnace body 1 and the amount adhering to the polyimide opening in the semiconductor substrate. There is also a tendency for the amount of adhesion to polyimide openings to increase. For this reason, for example,
As shown in FIG. 3, a semiconductor substrate 1 that has undergone a predetermined process
When a photosensitive polyimide 19 is used as a final protective film on the semiconductor substrate 18, a bonding pad 20 made of aluminum is formed on the semiconductor substrate 18, which becomes the polyimide opening.
There is a problem that reaction product gas of polyimide adheres to the surface of the polyimide. Therefore, during wire bonding in the subsequent assembly process, there was a problem in that the deposits 21 inhibited alloy formation between the bonding wire and the bonding pad, resulting in defective bonding.

Furthermore, when the reaction product gas generated when curing polyimide is discharged into the main exhaust pipe 13, the reaction product gas adheres to the main exhaust pipe 13 and the main exhaust pipe 13 becomes clogged after long-term use. There was a problem.

Further, normally, the exhaust ports of a plurality of devices including the polyimide curing device are connected to the common main exhaust pipe 13, but since the exhaust pressure varies depending on the operating state of each device, The state of discharge of reaction product gas from the polyimide curing device also varies. For this reason,
The above-mentioned problem is that the amount of adhesion inside the heating furnace body 1 varies, making it impossible to maintain a constant maintenance frequency, and the amount of adhesion to the polyimide opening in the semiconductor substrate varies, making the reproducibility unstable. There was a problem that defects occurred.

[0009] The present invention solves the above-mentioned problems at once, and can reduce the number of times the heating furnace main body, gas introduction pipe, board holder, etc. are cleaned, and also reduce re-adhesion of reaction product gas to the substrate. The purpose of this invention is to make it possible to maintain a substantially constant cleaning frequency in the exhaust system.

0010

[Means for Solving the Problems] In order to achieve the above object, a polyimide curing apparatus according to the present invention is provided with a heating furnace main body for heating and curing polyimide on a substrate, and an upper part of the heating furnace main body. an inlet opening to introduce carrier gas into the furnace; an exhaust port opening at the bottom of the heating furnace body to discharge reaction product gas generated in the furnace to the outside of the furnace together with the carrier gas; An exhaust pipe extending from the exhaust port to the outside of the furnace, a trap provided in the middle of the exhaust pipe for liquefying and discharging the reaction product gas flowing through the exhaust pipe, and a trap for heating the lower part of the heating furnace main body. an in-furnace lower part heat-retaining means for keeping the lower part of the furnace warm by heating the inside of the pipe by heating an upstream side of the trap in the exhaust pipe to keep the inside of the pipe warm; The exhaust gas is configured to include a pressure adjusting means for keeping the exhaust pressure substantially constant.

[0011]

[Operation] With the above configuration, the introduction port for introducing the carrier gas into the furnace is provided to open at the top of the heating furnace body, so the gas introduction pipe for introducing the carrier gas into the furnace is connected to the heating furnace body. Since there is no need to provide the gas inlet tube inside the tube, there is no problem of reaction product gas generated during curing of polyimide adhering to the gas introduction tube.

[0012] Furthermore, a trap for liquefying and discharging the reaction product gas is provided in the middle of the exhaust pipe extending from the exhaust port toward the outside of the furnace, and a trap inside the furnace for heating the lower part of the heating furnace body and keeping the lower part of the furnace warm. Since the lower part heat insulating means and the in-pipe heat insulating means heat the upstream part of the exhaust pipe than the trap to keep the inside of the pipe warm, the above-mentioned reaction product gas is absorbed into the lower part of the heating furnace main body, near the exhaust port, and in the exhaust pipe. It reaches the trap without being liquefied upstream of the trap, and is liquefied at once in the trap.

Furthermore, since a pressure regulating means for keeping the exhaust pressure substantially constant is provided downstream of the trap in the exhaust pipe, the exhaust pressure becomes substantially constant and there is no variation in the discharge state of the reaction product gas, so the exhaust system The amount of reaction product gas attached becomes approximately constant.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a polyimide curing apparatus according to an embodiment of the present invention. In the figure, 1 is a vertical heating furnace body made of a quartz tube, and the upper part of the heating furnace body 1 is a vertical heating furnace body made of a quartz tube. A main heater 4 is provided on the outer periphery of the furnace wall except for the lower part. Inside the heating furnace body 1, a shelf-shaped board jig 5 is held by a board support member 17. On the shelf of the board jig 5, a semiconductor substrate 6 having a patterned and non-imidized photosensitive polyimide is mounted. are set respectively.

As a feature of this embodiment, a gas inlet 2 is provided in the center of the hemispherical upper wall of the heating furnace body 1 for introducing a carrier gas, for example, N2 gas into the furnace. An exhaust port 3 is provided at the lower end of the peripheral wall of the heating furnace body 1 for discharging the reaction product gas generated in the furnace to the outside of the furnace together with the carrier gas. One end of an extending horizontal exhaust pipe 9 is attached. An upper part of a water-cooled trap 11 extending in the vertical direction is connected to the other end of the horizontal exhaust pipe 9, and one end of a communication pipe 22 is connected to the lower part of the water-cooled trap 11. A main exhaust pipe 13 extending in the vertical direction is connected to the other end of the communication pipe 22 via an auto damper 14 that serves as a pressure adjustment means for keeping the exhaust pressure substantially constant.

Furthermore, as a feature of this embodiment, a first heater is provided below the main heater 4 as a lower part of the furnace heat insulating means to heat the lower part of the heating furnace body 1 and keep the temperature of the lower part of the furnace constant.
A sub-heater 12A is provided, and a second sub-heater 12B is provided on the outer periphery of the horizontal exhaust pipe 9 as an internal heat-insulating means for heating the upstream portion of the exhaust pipe from the trap to keep the temperature inside the pipe constant. There is.

[0018] In the polyimide curing apparatus having the above structure,
When the main heater 4 is energized, the temperature inside the heating furnace body 1 is raised to about 400°C, and then maintained at about 400°C. As a result, polyimide on the semiconductor substrate 6 is imidized and photosensitive groups are removed, and a reaction product gas (outgas) 7 is generated accordingly. This reaction product gas 7 is discharged from the exhaust port 3 through the horizontal exhaust pipe 9 together with the carrier gas 8 introduced from the gas inlet 2 .

In the polyimide curing apparatus of the conventional structure, the temperature of the reaction product gas 7 decreases at a location away from the soaking area, particularly near the exhaust port 3, and the reaction product gas 7 liquefies, opening the lower end of the heating furnace body 1. However, in this embodiment, the first and second sub-heaters 12A, 1
2B, the reaction product gas 7 reaches the water-cooled trap 11 without being liquefied in the lower part of the heating furnace main body 1 and inside the horizontal exhaust pipe 9. Then, it is cooled all at once by the water-cooled trap 11 and adheres to the inner wall of the water-cooled trap 11.

Furthermore, in this embodiment, since the auto damper 14 is interposed between the communication pipe 22 and the main exhaust pipe 13, there is no variation in the discharge state of the reaction product gas, and the amount of adhesion in the exhaust system is reduced. Since this becomes approximately constant, the cleaning frequency of the exhaust system can be kept approximately constant.

Furthermore, since the gas inlet 2 is provided on the upper wall of the heating furnace main body 1, there is no need to arrange a gas inlet pipe inside the heating furnace main body 1 as in the conventional case. There is no problem of reaction product gas adhering to the outer wall.

[0022]

As explained above, according to the polyimide curing apparatus according to the present invention, the introduction port for introducing the carrier gas into the furnace is opened at the upper part of the heating furnace main body, so that the gas introduction pipe is connected to the heating furnace. There is no need to install it inside the main body, so
It is possible to eliminate the problem of reaction product gas adhering to the gas introduction pipe. In addition, there is a trap for liquefying and discharging the reaction product gas, a means for heating the lower part of the furnace body to keep the lower part of the furnace warm, and a part of the exhaust pipe upstream of the trap that heats the lower part of the furnace. Since the tube heat insulating means for keeping the inside of the tube warm is provided, the reaction product gas is less likely to adhere to the lower part of the heating furnace main body, the vicinity of the exhaust port, and the upstream side of the trap in the exhaust pipe.

Therefore, according to the present invention, compared to conventional apparatuses, it is possible to reduce the number of times the heating furnace main body, board holder, etc. are cleaned, and it is also possible to reduce re-adhesion of reaction product gas to the substrate. This makes it possible to form high-quality polyimide patterns.

Furthermore, according to the present invention, since the pressure adjusting means for keeping the exhaust pressure substantially constant is provided downstream of the trap in the exhaust pipe, there is no variation in the discharge state of the reaction product gas, and the reaction product in the exhaust system is Since the amount of gas attached is approximately constant, the frequency of cleaning in the exhaust system can be kept constant.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a polyimide curing device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a conventional polyimide curing device.

FIG. 3 is a cross-sectional view showing a state in which a reaction product gas is attached to a semiconductor substrate having a bonding pad patterned with photosensitive polyimide as a protective film.

[Explanation of symbols]

1...Heating furnace body 2...Gas inlet (inlet) 3...Exhaust port 4...Main heater 5...Board jig 6...Substrate with photosensitive polyimide 7...Reaction product gas 8...Carrier gas 9...Horizontal exhaust pipe 10... Lower end opening 11...water-cooled trap (trap) 12A...first sub-heater (furnace lower heat retention means) 12B...
Second sub-heater (pipe heat retention means) 13...Main exhaust pipe 14...Auto damper (pressure adjustment means) 15...Lower part of heating furnace main body 16...Gas introduction pipe 17...Board support member 18...Semiconductor substrate 19...Photosensitive polyimide 20... Bonding pad 21...attached matter

Claims (1)

[Claims] 1. A heating furnace body for heating and curing polyimide on a substrate; an inlet opening at the top of the heating furnace body for introducing a carrier gas into the furnace; an exhaust port that opens at the bottom and discharges the reaction product gas generated in the furnace together with the carrier gas to the outside of the furnace; an exhaust pipe that extends from the exhaust port toward the outside of the furnace; and an exhaust pipe that is provided in the middle of the exhaust pipe. a trap for liquefying and discharging the reaction product gas flowing through the exhaust pipe; a lower part of the furnace heating means for heating the lower part of the heating furnace body to keep the lower part of the furnace warm;
In-pipe heat retention means for heating an area upstream of the trap in the exhaust pipe to keep the inside of the pipe warm; and pressure adjustment means provided downstream of the trap in the exhaust pipe for keeping the exhaust pressure substantially constant. A polyimide curing device characterized by: