JPH05299335A - Baking equipment and baking method - Google Patents

Abstract

PURPOSE:To obtain a baking equipment and a baking method wherein generation of holes in a resist film is prevented which holes are to be formed by air bubbles generated at the time of baking. CONSTITUTION:After the surface of resist on a wafer which resist is hardened at the time of baking is etched a little by using oxygen plasma generated between electrodes 24 and 25, baking is again performed by applying a current to a heater 28. By repeating the above process, solvent in the resist can be completely evaporated, when the solvent is left in the resist and the surface is hardened. As the result, air bubbles are not generated when heat is applied in the later process, so that the manufacturing yield can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a baking apparatus and a baking method for photoresist (hereinafter referred to as resist) used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art FIG. 3 is a conceptual view of a conventional photoresist (hereinafter referred to as resist) baking apparatus used for manufacturing a semiconductor device. FIG. 3A is a side view of an oven-type baking device. This device is a heat insulation chamber 1
A wafer cassette 3 for holding the wafer 2 and a fan 4 for stirring the gas in the heat insulating chamber 1 are provided therein, and the gas in the heat insulating chamber 1 is connected via a pipe 5 connected to the side surface of the heat insulating chamber 1. And a circulation fan 6 for circulating. And, this device, by this circulation fan 6,
The wafer 2 is baked by circulating hot air of 100 to 150 ° C. in the heat insulating chamber 1.

FIG. 3B is a side view of a so-called hot plate type baking apparatus. This is generally a hot plate 7 and a heating means such as a heating heater for heating the hot plate 7 (see FIG. (Not shown), and in some cases, a cover for filling the surroundings with nitrogen or the like may be included. In this method, after applying a resist on the surface of the wafer 2, the wafer 2 is placed on a hot plate 7 heated to about 100 to 150 ° C. and the resist on the wafer 2 is baked for a certain period of time.

[0004]

A conventional device of this kind,
Particularly, in the oven type baking apparatus as shown in FIG. 3A, the resist is dried from the surface side, and the wafer 2
In many cases, the resist in the vicinity of the interface between the resist and the resist was not completely released, and the baking was completed.

Therefore, when heat is applied in the next step,
Since the surface of the resist is dried and hardened, the gas generated by the evaporation of the solvent is sealed and it becomes bubbles, and the bubbles burst and troubles such as opening holes in the resist film occur. Was there.

On the other hand, in the hot plate method of the type shown in FIG. 3B, heat is transferred from the wafer 2 side, so the above troubles can be ameliorated to some extent, but this is not sufficient as a countermeasure, and the occurrence of air bubbles due to surface drying occurs. It couldn't be prevented completely.

Therefore, an object of the present invention is to provide a baking apparatus and a baking method which solve the above problems.

[0008]

The present invention is directed to a vacuum chamber in which a wafer to be processed coated with a photoresist is set, and a supply amount control for controlling the supply amounts of oxygen and nitrogen into the vacuum chamber. System, a vacuum pump for exhausting the inside of the vacuum chamber, a temperature control system for controlling heating and cooling of the wafer provided in the vacuum chamber, and application of high-frequency power between a pair of electrodes provided in the vacuum chamber And an electric power control means for controlling the generation of oxygen plasma by the oxygen chamber, and a supply amount control system and a temperature control system for heating the wafer in an inert gas atmosphere in the vacuum chamber. Control the supply control system, temperature control system and vacuum pump to cool
Next, a central processing unit that repeats a sequence for controlling the power control unit so as to generate oxygen plasma a predetermined number of times is provided.

Further, according to the present invention, the first step is to make the inside of the vacuum chamber in which the wafer to be processed coated with the photoresist is set to be an inert gas atmosphere, and to heat the wafer set in the vacuum chamber. Then, the second step of baking the wafer and the third step of cooling the wafer to make the atmosphere in the vacuum chamber an oxygen-containing atmosphere, and applying high-frequency power between a pair of electrodes provided in the vacuum chamber to generate oxygen plasma. And a fourth step of etching the photoresist surface on the wafer and a fifth step of cutting off high frequency power, and repeating the sequence from the first step to the fifth step a predetermined number of times. To do.

[0010]

According to the above construction, even if the solvent remains inside the resist during baking and the remaining solvent is vaporized to form bubbles, the surface of the cured resist is hardened. Is etched and then rebaked, and this is repeated, whereby the solvent in the resist can be completely evaporated.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

An embodiment according to the present invention will be described with reference to FIG. FIG. 1 is a conceptual diagram of a photoresist (hereinafter referred to as resist) baking apparatus used for manufacturing the semiconductor device according to the present embodiment. The apparatus according to the present embodiment has a vacuum chamber 12 in which a wafer 11 coated with a resist is set.
A supply amount control system for controlling the supply amounts of oxygen and nitrogen into the vacuum chamber 12, a vacuum pump 13 for exhausting the vacuum chamber 12, a temperature control system for heating and cooling the wafer 11, and oxygen. A power control system for controlling plasma generation and a central processing unit 14 for controlling these control systems and the vacuum pump 13 are provided.

The central processing unit 14 includes a vacuum chamber 1
The supply amount control system and the temperature control system are controlled so as to heat the wafer 11 with the inert gas atmosphere in 2 and then the supply amount control system and the temperature control system are used so as to cool the wafer 11 with the oxygen chamber in the vacuum chamber 12 And vacuum pump 13
Is controlled, and then the three-step sequence for controlling the power control means for generating oxygen plasma is repeated a predetermined number of times until the resist baking is completed.

The supply amount control system comprises a nitrogen supply means and an oxygen supply means. The nitrogen supply means is a nitrogen cylinder 15
A pipe 16 connecting the nitrogen cylinder 15 and the vacuum chamber 12; and an adjusting valve 17 for adjusting the amount of nitrogen supplied into the vacuum chamber 12. On the other hand, the oxygen supply unit includes an oxygen cylinder 18, a pipe 19 that connects the oxygen cylinder 18 and the vacuum chamber 12, and an adjustment valve 20 that adjusts the amount of oxygen supplied into the vacuum chamber 12.
Further, the opening degree and the opening / closing operation of the adjusting valves 17 and 20 are
It is controlled by the gas switching controller 21 controlled by the central processing unit 14.

The vacuum pump 13 is connected to the vacuum chamber 12 by a pipe 22. In this pipe 22,
An adjustment valve 23 that adjusts the exhaust amount in the vacuum chamber 12 is provided. Further, the opening / closing operation of the adjusting valve 23 is controlled by the gas switching controller 21 controlled by the central processing unit 14.

An upper electrode 2 is provided on the ceiling of the vacuum chamber 12.
4 is provided, and the lower electrode 25 is provided on the floor. The power control system has a high-frequency power source 26 that applies high-frequency power between the upper electrode 24 and the lower electrode 25, and a switch 27 that turns on / off the application of this high-frequency power according to a command from the central processing unit 14.

The temperature control system has heating means for heating the lower electrode 25 and cooling means for cooling the lower electrode 25. The heating means includes a heating heater 28 and a heating controller 29 that controls the temperature of the heating heater 28, while the cooling means includes the cooling pipe 3.
0, a compressor 31 connected to the cooling pipe 30, and a cooling controller 32 for controlling the compressor 31. The heating controller 29 and the cooling controller 32 are controlled by a command from the central processing unit 14.

With such a structure, baking and slight etching of the resist surface can be alternately repeated. Hereinafter, this will be described with reference to the flowchart of FIG.

FIG. 2 is a flow chart for explaining each step of the manufacturing method according to the present invention. First, the resist-coated wafer 11 to be processed is set on the lower electrode 25 which also serves as a wafer holder. In this state, nitrogen gas is introduced into the vacuum chamber 12 from the nitrogen cylinder 15 through the pipe 16 to create a nitrogen gas atmosphere in the vacuum chamber 12 (step 201).

Next, the lower electrode 25 provided in the vacuum chamber 12 is heated by a heater 28 (100 to 1).
Then, the baking of the wafer 11 provided in the vacuum chamber 12 is started (step 20).
2). If left in this state for a while, drying proceeds from the interface between the wafer 11 and the resist and the surface of the resist.

However, since the heat is transferred from the lower electrode 25 through the wafer 11, the temperature on the wafer 11 side becomes higher than that on the surface, so that the vapor pressure of the solvent in the resist increases and the drying progresses, but the resist Although the surface side is cold,
Since the gas easily escapes, the drying progresses simultaneously with the wafer 11 side.
Therefore, even if the baking is continued as it is, the surface side of the resist is dried and hardened, so that there is no escape of gas due to the evaporation of the solvent, and bubbles are generated in the resist, or the drying ends insufficiently. In many cases.

Therefore, heating of the lower electrode 25 is interrupted (step 203), and then the lower electrode 25 is cooled by the cooling pipe 3.
It is cooled by 0 (step 204). As a result, the baking due to the heating of the wafer is temporarily stopped.

Next, the nitrogen in the vacuum chamber 12 is evacuated to a pressure of about 3 Pa by the vacuum pump 13 connected thereto (step 205), and the oxygen cylinder 18 is introduced into the vacuum chamber 12 through the pipe 19. A small amount of oxygen gas (about 50 SCCM) is introduced (step 20).
6).

Thereafter, high frequency power (eg, 13.56 MHz, 50 W) is applied from the high frequency power source 26 between the upper electrode 24 and the lower electrode 25 provided in the vacuum chamber 12 (step 207) to generate oxygen plasma. The resist surface generated and hardened by the previous baking is slightly etched (step 208). The resist etching rate can be controlled by the high frequency power, the oxygen gas supply amount, the degree of vacuum, and the like. With the surface only slightly etched and the hardened layer on the surface from the previous baking removed,
The high frequency power applied to the upper electrode 24 and the lower electrode 25 is cut off (step 209). Then, after eliminating oxygen and returning to a nitrogen gas atmosphere again, a series of operations from step 202 onward is repeated (step 210) until the baking is completed (step 211).

By doing so, even if the solvent remains inside the resist and the surface is hardened in the state where the solvent is vaporized to form bubbles, the resist on the hardened surface is etched and then rebaked. By repeating this, the solvent in the resist can be completely volatilized.
Therefore, bubbles are not generated even if heat is applied in the subsequent step, and there is an effect that the manufacturing yield of semiconductor devices is improved.

Although the resist film thickness is slightly reduced by etching, there is no problem if the film thickness is increased in advance.

[0027]

As described in detail above, according to the present invention, the surface of the resist hardened during baking is slightly etched by oxygen plasma and then rebaked, which is repeated. Even if the surface is hardened while remaining, the solvent in the resist can be completely volatilized.

As a result, even if heat is applied in a later step, bubbles or the like are not generated and the manufacturing yield of semiconductor devices can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a photoresist (hereinafter resist) baking apparatus used for manufacturing a semiconductor device according to an embodiment.

FIG. 2 is a flow chart for explaining each step of the manufacturing method according to the present invention.

FIG. 3 is a conceptual diagram of a conventional resist baking apparatus used for manufacturing a semiconductor device.

[Explanation of symbols]

11 ... Wafer, 12 ... Vacuum chamber, 14 ... Central processing unit, 21 ... Gas switching controller, 24 ... Upper electrode, 2
5 ... Lower electrode, 26 ... High frequency power source, 28 ... Heater,
29 ... Heating controller, 30 ... Cooling pipe, 32 ... Cooling controller.

Claims (2)

[Claims] 1. A vacuum chamber in which a wafer to be processed coated with a photoresist is set, a supply amount control system for controlling the supply amounts of oxygen and nitrogen into the vacuum chamber, and the inside of the vacuum chamber. And a temperature control system for controlling heating and cooling of the wafer, which is provided in the vacuum chamber, and oxygen plasma by applying high-frequency power between a pair of electrodes provided in the vacuum chamber. And a power control means for controlling the generation of the vacuum chamber, and controlling the supply amount control system and the temperature control system to heat the wafer with an inert gas atmosphere in the vacuum chamber, and then with an oxygen-containing atmosphere in the vacuum chamber. The supply control system, the temperature control system, and the vacuum pump are controlled to cool the wafer, and then the electric power is generated to generate the oxygen plasma. Baking apparatus of the photoresist, characterized in that it comprises a central processing unit to repeat the sequence for controlling the control means a predetermined number of times. 2. A first step of setting an inert gas atmosphere in a vacuum chamber in which a wafer to be processed coated with photoresist is set, and heating and baking the wafer set in the vacuum chamber. And a third step of cooling the wafer to create an oxygen-containing atmosphere in the vacuum chamber, and applying high-frequency power between a pair of electrodes provided in the vacuum chamber to generate oxygen plasma. And a fourth step of etching the photoresist surface on the wafer, and a fifth step of cutting off the high frequency power, and repeating the sequence from the first step to the fifth step a predetermined number of times. A characteristic photoresist baking method.