JP2003257957A - Semiconductor manufacturing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a mechanism for stably maintaining and automatically controlling the quantity of air to be mixed into a quartz tube. <P>SOLUTION: In semiconductor manufacturing equipment wherein oxygen or a steam gas produced by the reaction of oxygen and hydrogen is introduced, and a semiconductor substrate is heated up to a prescribed temperature under prescribed exhaust pressure and then is heat-treated to form an insulation film, or in semiconductor manufacturing equipment wherein nitrogen or a mixed gas of nitrogen and oxygen is introduced, and a semiconductor substrate is heated up to a prescribed temperature under prescribed exhaust pressure and then is heat-treated to diffuse impurities in the semiconductor substrate, treated gas is exhausted by the exhaust pressure being automatically controlled by means of a variable valve provided in an exhaust pipe to reduce variations in the thickness of an oxide film grown on the semiconductor substrate. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, such as an insulating film forming apparatus and a thermal diffusion apparatus, which is subjected to a heat treatment, in a quartz tube when an insulating film of a semiconductor substrate is formed and impurities are thermally diffused. The present invention relates to an intake / exhaust control method, and more particularly to a measure for stabilizing the growth rate of an oxide film that grows when it is put into an insulating film forming apparatus for a semiconductor substrate and a thermal diffusion apparatus.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, an insulating film forming process of forming an insulating film for electrical insulation on a semiconductor substrate, and introducing impurities into the semiconductor substrate and diffusing the impurities into the semiconductor substrate. Insulating film forming devices and thermal diffusion devices are widely used in the thermal diffusion process. FIG. 14 shows a cross-sectional view of a general device.

In the apparatus shown in FIG. 14, a quartz boat 1 on which a semiconductor substrate is mounted is inserted into a quartz tube 3 surrounded by a heater 2 whose temperature can be controlled. At this time, the heater 2 is controlled to keep the temperature in the quartz tube 3 at a temperature of 300 ° C to 800 ° C. The inside of the quartz tube 3 is filled with high-purity nitrogen gas from the gas inlet 4 in order to prevent foreign matter from entering from the outside of the quartz tube.

After inserting the semiconductor substrate, the temperature inside the quartz tube 3 is raised from 650 ° C. to 1 by heating the heater 2.
Raise to 150 ° C. Then, when forming an insulating film on the semiconductor substrate in the quartz tube 3, oxygen or steam gas obtained by reacting oxygen and hydrogen in an external combustion tube is introduced from the gas inlet 4.

The introduced gas is discharged from the quartz tube 3 through the gas exhaust port 5. After the predetermined processing time has passed,
By controlling the heater 2, the temperature inside the quartz tube 3 is lowered to 300 ° C. to 800 ° C., and the quartz boat 1 on which the semiconductor substrate is mounted is taken out of the quartz tube 3. As nitrogen, oxygen, and hydrogen used at this time, a high-purity gas in which particles and impurities in the gas are extremely reduced is used in order to minimize contamination in the wafer.

[0006]

However, the above-mentioned conventional insulating film forming apparatus and thermal diffusion apparatus have the following problems.

When the quartz boat 1 was inserted into the quartz tube 3, air was mixed into the quartz tube 3 and oxygen and moisture in the air reacted on the surface of the semiconductor substrate to form an oxide film. Further, the inflow amount of air fluctuates depending on the joining state between the quartz tube 3 and the gas introduction port 4 and the change of the exhaust pressure at the gas exhaust port 5.

The connecting portion between the quartz tube 3 and the gas inlet 4 is a sliding contact between the quartz parts, but the inflow of air from the outside of the quartz to the inside is prevented by an omni seal. Omni seal is a stainless steel O-ring
It is a ring for gas sealing sandwiched between a sheet of Teflon (registered trademark) O-rings. However, in this case, when the quartz tube 3 and the gas introduction port 4 are installed so that their central axes are deviated from each other, the omni seal cannot completely prevent the inflow of air from the outside of the quartz, and the amount of air mixing varies. FIG. 15 shows a state in which a quartz tube and an omni seal at a gas inlet of a conventional insulating film forming apparatus are installed.

Further, when the quartz boat 1 is inserted into the quartz tube 3 by changing the exhaust pressure for exhausting the gas in the quartz tube, the air near the quartz boat insertion port below the quartz tube 3 is introduced into the quartz tube 3. The amount of involvement varies.

Due to these fluctuations, the thickness of the oxide film grown on the semiconductor substrate increases or decreases in the insulating film forming apparatus and the thermal diffusion apparatus. In addition, the concentration of impurities such as boron, phosphorus, and arsenic implanted on the surface of the semiconductor substrate varies on the surface of the semiconductor substrate due to the increase or decrease in the thickness of the oxide film. The concentration of impurities implanted into the surface of the semiconductor substrate greatly affects the threshold voltage and the sheet resistance characteristics of the transistor.

The present invention has been made in view of the above problems, and its main purpose is to maintain a stable amount of air mixed in a quartz tube and automatically control it. To provide.

[0012]

A semiconductor manufacturing apparatus of the present invention introduces oxygen or steam gas produced by reacting oxygen and hydrogen, and raises a semiconductor substrate to a predetermined temperature with a predetermined exhaust pressure. In the manufacturing method of forming an insulating film by heat treatment, the treated gas is discharged by automatically controlling the exhaust pressure by a variable valve provided in the exhaust pipe.

In the semiconductor manufacturing apparatus of the present invention, nitrogen or a mixture of nitrogen and oxygen is introduced into the gas, and the semiconductor substrate is heated to a predetermined temperature with a predetermined exhaust pressure to heat-treat the semiconductor substrate so that impurities are added to the semiconductor substrate. In the manufacturing method for diffusing, the processed gas has a function of automatically controlling the exhaust pressure by a variable valve provided in the exhaust pipe and discharging the gas.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a conventional semiconductor manufacturing apparatus such as an insulating film forming apparatus and a thermal diffusion apparatus, the transistor threshold voltage of the device is changed before and after the maintenance of the quartz tube or the maintenance of the exhaust motor. It was found that the film thickness of the oxide film grown when the quartz boat was inserted was examined, and it was found that the film thickness fluctuated before and after the maintenance.

From this, the state of connection between the quartz tube and the gas inlet before and after the maintenance of the insulating film forming apparatus and the heat diffusion apparatus, or the exhaust pressure of the portion exhausted from the quartz tube before and after the periodic maintenance of driving exhaust changes. By doing so, the amount of air mixed in when the quartz boat was inserted was changed, and it was estimated that the thickness of the oxide film grown by this air was changed.

The first embodiment will be described below.

The connecting portions of the quartz tube and the gas introduction port of the insulating film forming apparatus and the heat diffusion apparatus are made to mate with each other, but the inflow of air from the outside of the quartz to the inside is as shown in FIG. , Change from omni seal to O-ring and crimp it to prevent.

As a result, as shown in FIG. 2, in the conventional omni seal, the oxide film thickness grown on the semiconductor substrate is
Although it is 0.8 nm to 2.7 nm, when it is changed to an O-ring, it becomes 0.3 nm to 0.9 nm, which reduces the variation of the oxide film grown on the semiconductor substrate.

The second embodiment will be described below.

As shown in FIG. 3, by providing an APC (AUTO PRESSURE CONTROLLER) having a butterfly valve for controlling the pressure exhausted from the quartz tube to be constant, variation in the exhaust pressure is reduced, and the quartz boat is replaced with the quartz tube. It is possible to stabilize the film thickness of the oxide film that grows when it is inserted into.

The effect of the implementation is shown in FIG. Before introducing the APC valve, the fluctuation of the exhaust pressure is ₂ mmH ₂ O to 15 mm.
It was H ₂ O, but after introducing the APC valve, it was 1 mmH ₂
It becomes O-9 mmH ₂ O to reduce the variation in pressure.

FIG. 5 shows the effect of stabilizing the film thickness of the oxide film grown when the quartz boat is inserted into the quartz tube. Before introducing the APC valve, the oxide film grown when the quartz boat was inserted into the quartz tube had a thickness of 0.3 nm to 0.9.
After the introduction of the APC valve, the oxide film grown when the quartz boat was inserted into the quartz tube was 0.4 nm.
The thickness becomes m to 0.75 nm, and the variation of the oxide film grown on the semiconductor substrate is reduced.

However, even if this APC is provided, the exhaust gas pressure control cannot follow when the prime mover exhaust pressure changes abruptly.

The third embodiment will be described below.

As shown in FIG. 6, the exhaust part has an APC valve.
Install a pressure damper between the tube and the quartz tube. This pressure
By installing a force damper, the exhaust pressure changes rapidly
Is absorbed by the pressure damper, and the APC valve exhaust pressure
Can follow fluctuations in force. The effect of implementation is shown in FIG.
A pressure damper is installed between the APC valve and the quartz tube.
Therefore, before installing the APC valve, exhaust pressure
Variation of 1mmH ₂O-9mmH₂It was O but AP
Exhaust pressure variation is 1mm after C valve is installed.
H₂O ~ 6mmH₂Reduced to O.

However, if water vapor is present in the gas to be exhausted, the water vapor agglomerates into water droplets at the pressure measurement port, and the pressure suddenly drops.

The fourth embodiment will be described below.

As shown in FIG. 8, in order to prevent water droplets from adhering to the port of the pressure sensor due to water vapor in the exhaust gas, a water cooling trap for removing the water vapor in the exhaust gas is placed in front of the exhaust pressure measuring portion. Set up.

As a result, the exhaust pressure can be controlled stably. The effect of implementation is shown in FIG. Before installing a water-cooled trap in front of the exhaust pressure measurement part, the variation in exhaust pressure is 1 mm.
It was H ₂ O to ₆ mmH ₂ O, but after the water cooling trap was installed in front of the measurement part of the exhaust pressure, the variation of the exhaust pressure was
It was reduced to variations in 5mmH ₂ O~6mmH ₂ O.

A fifth embodiment will be described below.

As shown in FIG. 10, exhaust pressure and APC
By automatically measuring the degree of opening, an alarm is generated in the controller of the device when a pressure control abnormality occurs. Then, the operation of the device is automatically stopped.

A flowchart at that time is shown in FIG. If the opening of the APC valve is within the criterion, the process continues. If the opening of the APC valve is outside the criterion, an alarm is generated and the current process is continued. The equipment is stopped after the processing is completed.

In the present invention, the insulating film forming apparatus and the thermal diffusion apparatus shown in FIG. 12 are used to control the exhaust pressure, so that the variation of the oxide film grown when the quartz boat is inserted is reduced and the threshold value of the transistor in the semiconductor and Sheet resistance is stable.

The effect of the implementation is shown in FIG. When the oxide film thickness that grows when the quartz boat is inserted is 2.25 nm, the variation in the threshold value of the transistor is 0.12 V, but the oxide film thickness that grows when the quartz boat is inserted is 0.6 n.
At m, the variation of the transistor threshold is
Reduce to 0.04 volts.

[0035]

According to the present invention, the inflow of air into the quartz tube from the connecting portion between the quartz tube and the gas inlet can be reduced. Further, the exhaust pressure for exhausting the gas in the quartz tube is controlled to be constant. In addition, a pressure damper is provided in the exhaust in order to follow rapid changes in exhaust pressure.

Further, in order to reduce pressure variations due to water vapor in the exhaust gas, a water cooling trap is provided in the exhaust section. These inventions alleviate variations in pressure and reduce variations in the amount of air mixed in the quartz tube when the quartz boat is inserted. When the quartz boat is inserted into the quartz tube, the growth rate of the oxide film that grows on the semiconductor substrate is maintained in a stable state, and the amount of impurities such as boron, phosphorus, and arsenic implanted into the surface of the semiconductor substrate is diffused. And the amount of diffusion into the oxide film can be made constant.
That is, it is possible to provide a method and a mechanism for stably maintaining the amount of air mixed in the tube in order to stabilize the transistor threshold value and the sheet resistance of the device and automatically controlling this.

[Brief description of drawings]

FIG. 1 is an explanatory diagram related to improvement of a sealing method for a connecting portion between a quartz tube and a gas introduction port in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 2 is a diagram showing the effect of reducing the amount of trapped oxidation by improving the sealing method of the connecting portion between the quartz tube and the gas inlet in the insulating film forming apparatus and the heat diffusion apparatus.

FIG. 3 is a diagram showing an outline of a mechanism (auto pressure control) for controlling exhaust gas pressure in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 4 is a diagram showing an effect of reducing variations in exhaust pressure by an auto pressure control valve (APC valve) in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 5 is a diagram showing an effect of reducing variation in the amount of an oxide film grown when a quartz boat is inserted by an auto pressure control valve (APC valve) in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 6 is a diagram showing an outline of a mechanism (pressure damper) for controlling rapid pressure fluctuations in the insulating film forming apparatus and the heat diffusion apparatus.

FIG. 7 is a diagram showing an effect of reducing variations in exhaust pressure by a mechanism (pressure damper) that controls rapid pressure fluctuations in the insulating film forming apparatus and the heat diffusion apparatus.

FIG. 8 is a diagram showing an outline of a mechanism (water cooling trap) for stably controlling exhaust pressure in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 9 is a diagram showing an effect of reducing variation in exhaust pressure by a mechanism (water cooling trap) for stably controlling exhaust pressure in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 10 is a schematic view of a mechanism for automatically controlling exhaust pressure in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 11 is a flowchart regarding automatic control of exhaust pressure in an insulating film forming apparatus and a heat diffusion apparatus.

FIG. 12 is a schematic view of all the mechanisms for automatically controlling the pressure of exhaust gas in the insulating film forming device and the heat diffusion device.

FIG. 13 is a diagram for explaining a change in threshold value of a semiconductor transistor and a change in film thickness of an oxide film grown when a quartz boat is inserted in an insulating film forming apparatus and a thermal diffusion apparatus.

FIG. 14 is a cross-sectional view of a conventional insulating film forming apparatus for forming an insulating film.

FIG. 15 is an explanatory diagram of an installation state of an omni seal at a connecting portion between a quartz tube and a gas inlet in a conventional insulating film forming apparatus.

[Explanation of symbols]

1 quartz boat 2 heater 3 quartz tube 4 gas inlet 5 gas outlet 6 caps

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shuji Matsumoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5F045 AB32 AC11 AC18 BB08 EE01                       EG06 EG08 GB06

Claims (6)

[Claims] 1. A semiconductor manufacturing apparatus for forming an insulating film by introducing oxygen or a water vapor gas produced by reacting oxygen and hydrogen, heating a semiconductor substrate to a predetermined temperature with a predetermined exhaust pressure, and performing heat treatment. 2. A semiconductor manufacturing apparatus, wherein the processed gas is discharged by automatically controlling the exhaust pressure with a variable valve provided in the exhaust pipe. 2. A semiconductor manufacturing apparatus in which impurities are diffused into a semiconductor substrate by introducing nitrogen or a mixture of nitrogen and oxygen into a gas, heating the semiconductor substrate to a predetermined temperature with a predetermined exhaust pressure, and heat-treating the semiconductor substrate , A semiconductor manufacturing apparatus having a function of automatically controlling the exhaust pressure and discharging the processed gas by a variable valve provided in an exhaust pipe. 3. The semiconductor manufacturing apparatus according to claim 1, further comprising a water-cooled trap that removes water in the gas processed before the exhaust pressure measuring unit. 4. The semiconductor manufacturing apparatus according to claim 1, wherein a damper is provided in the exhaust gas, and a function of responding to a sudden exhaust gas pressure fluctuation by letting it escape to the atmosphere is provided. 5. The semiconductor manufacturing apparatus according to claim 1, wherein when the processed gas is discharged by automatically controlling the exhaust pressure with a variable valve provided in an exhaust pipe, the opening of the variable valve is set to the device. A semiconductor manufacturing device that has a function of displaying on the monitor screen of, and generates an alarm when it goes out of a predetermined setting range, and then stops the device when the ongoing processing is completed. 6. The semiconductor manufacturing apparatus according to claim 1 or 2, which has a function of preventing a leak due to an O-ring at a quartz component sliding portion of an air intake portion in order to prevent leakage of gas introduced into the apparatus and inflow of air. A semiconductor manufacturing apparatus having.