JPH10163116A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize (shorten) a cleaning time and to reduce the amount of etching gas used by accurately detecting the end point of cleaning in the case when ClF3 self cleaning is used for cleaning a CVD device by the etching gas. SOLUTION: A device has a vertical reaction chamber 10 in double tube structure, a controller 20 that is provided for controlling the temperature of the reaction chamber, monitors the temperature in the reaction chamber based on the electromotive force of a thermocouple 5, and controls the heating operation of a heater 4, and a mechanism for self-cleaning a deposition film in the reaction chamber by feeding an etching gas introduced from an etching gas introduction port 6 into the reaction chamber and evacuating it from a gas exhaust port 8. Then, the controller has a function for detecting the end point of etching removal of the deposition film by essentially monitoring the change in temperature within the reaction chamber in the case of self cleaning.

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 and a cleaning method thereof, and more particularly to a CVD apparatus and a cleaning method of a CVD apparatus using ClF ₃ self-cleaning.

[0002]

2. Description of the Related Art Conventionally, C in a semiconductor device manufacturing process
When ClF ₃ self-cleaning is used for cleaning the VD apparatus, the conditions of temperature, gas flow rate, and gas pressure are calculated, and then the calculation is performed based on the cumulative film thickness on the surface of the quartz tube of the CVD apparatus and the etching rate. Cleaning was performed at the specified time.

When the calculation is performed based on the cumulative film thickness on the quartz tube surface and the etching rate as described above, the cumulative film thickness is a calculated value. As a result, cleaning is performed by designating a long time to prevent insufficient etching.

However, since ClF ₃ gas used as an etching gas for cleaning a CVD apparatus is expensive unlike ordinary etching gas, it is difficult to perform cleaning by designating a long time for the use of ClF ₃ gas. And the cost of cleaning increases.

On the other hand, in order to detect the end point of the cleaning, there is a conventional example in which the end point is detected indirectly by monitoring the column temperature outside the exhaust gas treatment apparatus. However, the column temperature hardly changes. Or, at present, it changes depending on the amount of N ₂ gas added to dilute the ClF ₃ gas, and it is difficult to accurately detect the end point. If it is difficult to detect the end point accurately as described above, waste of time is increased, and the cleaning cost is increased.

[0006]

SUMMARY OF THE INVENTION As described above, CVD
C to clean the device with etching gas
lF ₃ when using the self-cleaning, conventionally, there is a problem that the cost of cleaning is increased, a good cleaning method efficient are required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to accurately detect the end point of cleaning when using ClF ₃ self-cleaning to clean a CVD apparatus with an etching gas.
It is an object of the present invention to provide a semiconductor manufacturing apparatus capable of optimizing (reducing) the cleaning time and reducing the amount of etching gas used.

[0008]

According to the present invention, there is provided a semiconductor manufacturing apparatus comprising: an outer tube having a closed upper end face; and an inner tube disposed vertically inside the outer tube. A vertical reaction chamber having a double tube structure for performing a film forming process on a wafer to be processed mounted on a boat, and the reaction chamber is disposed so as to surround the outer tube, and the reaction chambers are vertically arranged in plural numbers. A heater provided to heat each of the divided zones; a plurality of thermocouples provided to sense the temperatures of the plurality of zones correspondingly; and controlling the temperature of the plurality of zones. For monitoring the temperature in the reaction chamber based on the electromotive force of the plurality of thermocouples,
A controller for controlling a heating operation of the heater, and an etching gas for etching and removing a deposited film attached to the inner surface of the outer tube, the surface of the inner tube, and the surface of the boat during the film forming process of the wafer to be processed in the reaction chamber. An etching gas inlet provided at a lower portion of the reaction chamber for introducing the gas under the inner tube; and a lower portion of the reaction chamber for discharging gas from below between the outer tube and the inner tube to the outside. A gas outlet provided in the controller, the controller further comprises, in a process in which the etching gas introduced from the etching gas inlet flows through the reaction chamber and is discharged from the gas outlet, By monitoring a change in temperature in the reaction chamber, the deposited film is removed by etching. And having a function of detecting the end point.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 schematically shows a configuration of a CVD apparatus according to a first embodiment of the semiconductor manufacturing apparatus of the present invention.

The CVD apparatus shown in FIG. 1 has a cylindrical base (manifold) 11 having an upper surface opened, and is vertically disposed on the base, and has a lower surface opened and an upper end surface closed. A first quartz tube (outer tube) 1 and a second quartz tube, which is supported by a flange portion projecting inward from the side wall of the base 11 inside the outer tube 1 and disposed vertically. A vertical reaction chamber 10 having a double tube structure having a tube (inner tube) 2 is provided.

The boat 3 mounts a semiconductor wafer to be processed (not shown) in a horizontal state, and is installed inside the inner tube 2. The heater 4 is provided so as to surround the outside of the outer tube 1, and is provided so as to heat, for example, four zones each of which vertically divides the reaction chamber 10.

Here, the four zones are referred to as a lower (L) zone, a center lower (CL) zone, a center upper (CU) zone, and an upper (U) zone in order from the lower side to the upper side.

Thermocouple (heater thermocouple, spike thermocouple)
Numerals 5 are embedded in the heater 4 and four are provided for correspondingly sensing the temperature outside the outer tube of the four zones.

The cascade thermocouple 7 is provided between the outer tube 1 and the inner tube 2 and
Four zones are provided for sensing the temperatures of the four zones within zero, and are housed in the quartz tube 12.

The controller 20 is provided for controlling the temperature of the four zones, monitors the temperature in the reaction chamber 10 based on the electromotive force of the four thermocouples 5, and controls the temperature of the heater 4.
This controls the heating operation.

As a method for controlling the temperature of the zone, a heater control method for controlling the temperature of the heater 4 based on the electromotive force (temperature detection output) of the four heater thermocouples 5 and a method for controlling the four cascade thermocouples 7 There is a cascade control method for controlling the temperature of the heater 4 based on the electromotive force. At least one of the detection output of the heater thermocouple 5 and the detection output of the cascade thermocouple 7 may be taken.

The gas inlet 6 is connected to the inner surface of the outer tube 1 during the film formation of the wafer to be processed in the reaction chamber 10.
An etching gas (ClF ₃ gas in this example) for etching off a deposited film attached to the surface of the inner tube 2, the surface of the boat 3, and the surface of the quartz tube 12 covering the cascade thermocouple 7 is externally supplied to the inner tube 2. Is opened at the lower part of the reaction chamber 10 (for example, the side wall of the base 11 below the lower end face of the inner tube 2).

The gas outlet 8 is connected to the outer tube 1.
The inner tube 2 is provided to discharge gas from below to the outside from below, and is opened to the side wall of the base 11 below the lower end surface of the outer tube 1, for example.

In the present invention, the controller 2
Further, in the process in which the etching gas introduced from the etching gas inlet 6 flows through the inside of the reaction chamber 10 as shown by the arrow in the drawing and is discharged from the gas outlet 8, the temperature of the inside of the reaction chamber 10 substantially decreases. It has a function of detecting the end point of the etching removal of the deposited film by monitoring the change.

Specific examples of the function of detecting the end point of the etching removal include a change in radiant heat generated when the deposited film is removed by etching or a change in electromotive force of a thermocouple due to a change in reaction heat between the etching gas and the deposited film. Has the function of detecting the end point of the etching removal of the deposited film based on the above, or the function of detecting the end point of the etching removal of the deposited film by monitoring a change in the heater control output.

In FIG. 1, the surface of the wafer to be processed is C
A film-forming gas (eg, SiH
The illustration of the introduction ports of the ₄ gases and others), the introduction ports of the purge gas, and the heat insulating material covering the heater 4 is omitted.

FIG. 2 is an enlarged view showing a state in which the CU zone 9 surrounded by the ellipse in FIG. 1 is taken out and a deposited film is attached. FIG. 3 schematically shows an example of the relationship between the elapsed cleaning time and the heater temperature when etching (cleaning) the deposited film attached to the reaction chamber of the CVD apparatus in FIG.

Next, referring to FIGS. 2 and 3, FIG.
An example of using the CVD apparatus will be described. At the time of film formation processing of the wafer to be processed, as shown in FIG. 3, in addition to the surface of the wafer to be processed, the inner surface of the outer tube 1 and the surface (inner and outer surfaces) of the inner tube 2, the surface of the boat 3 and the quartz tube 12. A film (denoted by 13 in FIG. 2) deposits and adheres to the surface.

In order to clean the inside of the reaction chamber (to remove the deposited film 13 by etching) after removing the wafer to be processed after the film formation, the set temperature in the reaction chamber 10 is set to, for example, 600.degree. introducing a ClF ₃ gas into the tube from the inlet 6, FIG. 1 the ClF ₃ gas
The gas flows through the gas discharge port 8 as indicated by the arrow in FIG.

As described above, the ClF ₃ gas introduced into the lower portion of the inner tube 2 from the gas inlet 6 flows through the inner tube 2 from the lower side to the upper side, and the deposited film on the inner wall surface of the inner tube 2 and the boat 3 The deposited film on the surface is etched, and the deposited film on the outer wall surface of the inner tube 2, the inner wall surface of the outer tube 1, and the surface of the quartz tube 12 in the process of flowing from above to below between the outer tube 1 and the inner tube 2. 13 is etched.

As described above, when the deposited film 13 is etched from the inside of the inner tube 2 and the bottom of the boat 3 to the top, the radiant heat transmitted to the thermocouples 5 and 7 increases, and the thermocouples 5 and 7 are generated. The electromotive force increases (temperature rise is detected).

When the heater control method is adopted, the controller 20 controls the temperature of the heater 4 to be lowered based on the temperature rise detection output by the heater thermocouple 5 so as to maintain the set temperature in the reaction chamber 10. However, since this temperature control cannot immediately follow the temperature rise of the thermocouple 5, the thermocouple 5
Temperature rise for a while.

As the above etching progresses, the temperature control by the controller 20 gradually follows the temperature rise of the thermocouple 5, and the temperature of the thermocouple 5 becomes lower.
It approaches the set temperature within 0.

After an appropriate time from when the temperature of the thermocouple 5 reaches the set temperature, the introduction of ClF ₃ gas is automatically stopped, and the gas remaining in the reaction chamber 10 is removed from the gas outlet 8. Etching is completely completed when discharged to the outside. In this case, the introduction of the ClF ₃ gas can be stopped before the etching is completed in anticipation of the etching effect of the residual gas.

After the etching is completed, the inside of the reaction chamber 10 is purged with N ₂ gas, and the cleaning is completed. That is, the above-described heater control method uses the deposited film 13
Is used because the measured temperature of the heater thermocouple 5 and the cascade thermocouple 7 approaches the set temperature when the deposited film 13 disappears.
When the temperature of the thermocouple 5 reaches the set temperature, the etching process ends.

When the temperature measured by the heater thermocouple 5 becomes higher than the set temperature, the heater control output of the controller 20 decreases, and when the deposited film runs out, the heater control output becomes stable. Therefore, the heater control output is monitored. If the time when the heater control output is stabilized is detected, the end point of the etching can be detected.

[0032] Incidentally, the reaction formula in the case the deposited film is a _{polysilicon, 2Si + 4ClF 3 → SiF 4} + SiCl 4 + 2F 2 + 2Cl 2 ...... (1) and is considered as the main _{reaction, 3Si + 4ClF 3 → 3SiF 4} + 2Cl ₂ …… (2) is said to occur as a minor reaction.

Here, it is known that the reaction between the reaction gases SiH ₄ and ClF ₃ is an exothermic reaction, and the reaction product is the same as the reaction product of the formula (1). The reactions 1) and (2) are exothermic reactions.

Therefore, the present invention is not limited to the method of detecting the radiant heat transmitted to the thermocouples 5 and 7 at the time of etching as in the above-described embodiment, and the method of detecting the heat due to the exothermic reaction during the etching of ClF ₃ and the deposited film is used. Can be implemented in the same manner as in the above embodiment.

The heater thermocouple 5 used in the above-described heater control method can easily detect a temperature change due to radiant heat from the outer tube 1. On the other hand, the cascade thermocouple 7 receives heat due to the exothermic reaction of the deposited film 13 attached to the outer tube 1 and the inner tube 2, and is more likely to detect a temperature change than the heater thermocouple 5.

Therefore, when detecting heat due to an exothermic reaction at the time of etching, a cascade control method may be employed. In this case, the controller 20 controls the temperature of the heater 4 based on the electromotive force (temperature detection output) of the cascade thermocouple 7, and when the deposited film runs out, the measured temperature of the cascade thermocouple 7 approaches the set temperature. Thus, the end point of the etching can be detected.

When the temperature measured by the cascade thermocouple 7 becomes higher than the set temperature, the heater control output of the controller 20 decreases, and when the deposited film runs out, the heater control output becomes stable. Therefore, the heater control output is monitored. In addition, the end point of the etching can be detected by detecting the time when the heater control output is stabilized.

Here, the characteristics of FIG. 3 will be described in detail. FIG. 3 shows an example of a heater temperature characteristic when a ClF ₃ gas is flowed at a set temperature of 600 ° C. when the above-described heater control method is adopted.

In this case, the temperature is previously corrected so that the temperature in the state where the deposited film is adhered becomes uniform, and the set temperature of the L zone is set higher than 600 ° C. Radiation heat or reaction heat increases as the etching of the deposited film proceeds, and the temperature of the CL zone increases, and then the temperature of the CU zone further increases. In the L zone and the U zone, since the heater thermocouple 5 is separated from the tube,
Low temperature change detection sensitivity. When the deposited film disappears, the radiant heat or the reaction heat decreases, and the temperature of the CU zone and the CL zone starts to decrease. When the deposited film disappears, the radiant heat or the reaction heat disappears, and the CU zone and the CL heat disappear.
The zone temperature becomes constant at the set temperature.

That is, the temperature in the reaction chamber is monitored, and the time when the temperature rises due to the start of cleaning and then falls and becomes constant (about 35 minutes after the start of cleaning in this example) is determined as the end point of the etching removal of the deposited film. It becomes possible to determine.

At this time, the introduction of the etching gas is stopped shortly before the CU zone and the CL zone become constant at the set temperature (about 30 minutes after the start of cleaning in this example), and the residual gas is evacuated. ing. As a result, the temperature of the CU zone is rapidly lowered. It is considered that the reason for this is that the heat of reaction has disappeared.

The state of the tube after the etching process is as follows: the deposited film inside the inner tube 2 and the boat 3
The deposited film on the surface of was completely removed by etching. However, the deposited film still remained outside the inner tube 2 and inside the outer tube 1. This is probably because the inside of the outer tube 1 and the outside of the inner tube 2 did not completely return to the set temperature.

Therefore, when the introduction of the etching gas is continued without stopping the introduction of the etching gas and evacuation of the residual gas about 30 minutes after the start of the cleaning, the inside of the outer tube 1, the inner tube, 2
As the deposited film 13 on the outside of the quartz tube 12 and the surface of the quartz tube 12 are etched, the change in the temperature of the CL zone becomes more remarkable, and an example thereof is shown in FIG.

FIG. 4 shows a CL in which the temperature of the CL zone further increases after the time when the CU zone becomes constant at the set temperature.
FIG. 3 shows an example of the heater temperature characteristics when the introduction of the etching gas is stopped and the residual gas is evacuated when the temperature of the zone starts to drop (about 65 minutes after the start of cleaning). The characteristics and the tendency of change are similar.

As a result, when the inside of the outer tube 1 and the outside of the inner tube 2 completely return to the set temperature, the deposited film on the inside of the outer tube 1, the outside of the inner tube 2 and the surface of the quartz tube 12 is also removed. Is done.

[0046]

As described above, according to the semiconductor manufacturing apparatus of the present invention, when ClF ₃ self-cleaning is used to clean a CVD apparatus with an etching gas, the end point of the cleaning is accurately detected, and the cleaning time is optimized. (Reduction) and the amount of etching gas used can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of a semiconductor manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 shows a center upper (C) surrounded by an ellipse in FIG.
U) The figure which expanded and shows the state which took out the zone 9 and the deposited film adhered.

FIG. 3 is a diagram schematically illustrating an example of a relationship between a cleaning elapsed time and a heater temperature during cleaning of a reaction chamber of the CVD apparatus in FIG. 1;

FIG. 4 is a diagram illustrating a center upper unit (CU) for controlling a heater during cleaning of a reaction chamber of the CVD apparatus of FIG. 1;
When the temperature of the center lower (CL) zone starts to fall after the zone becomes constant at the set temperature, the introduction of the etching gas is stopped and the residual gas is evacuated. The figure which shows an example of a characteristic.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer tube, 2 ... Inner tube, 3 ... Boat, 4 ... Heater, 5 ... Heater thermocouple, 6 ... Etching gas inlet, 7 ... Cascade thermocouple, 8 ... Gas outlet, 9 ... Center upper (CU) Zone: 10: reaction chamber, 11: base, 12: quartz tube, 13: deposited film, 20: controller.

Claims (8)

[Claims] 1. A film formation method for a wafer to be processed, comprising: an outer tube having an upper end surface closed, and an inner tube vertically arranged inside the outer tube, and mounted on a boat inside the inner tube. A vertical reaction chamber having a double tube structure for performing a process, disposed so as to surround the outside of the outer tube, and provided so as to heat zones each of which is vertically divided into a plurality of reaction chambers. A heater, a plurality of thermocouples provided to sense the temperatures of the plurality of zones correspondingly, and a plurality of thermocouples provided for controlling the temperature of the plurality of zones,
A controller that monitors a temperature in the reaction chamber based on electromotive forces of the plurality of thermocouples and controls a heating operation of the heater; and, when forming a wafer to be processed in the reaction chamber, an inner surface of an outer tube; An etching gas inlet provided at a lower portion of the reaction chamber for introducing an etching gas for etching and removing a deposited film attached to the surface of the tube and the surface of the boat below the inner tube; and A gas outlet provided at a lower portion of the reaction chamber for discharging gas from below to an outside from an inner tube, the controller further comprising: an etching gas introduced from the etching gas introduction port. Flows through the reaction chamber and is discharged from the gas outlet, The semiconductor manufacturing apparatus characterized by having a function of detecting the end point of the etching removal of the deposited film by monitoring the change in temperature in the 応室. 2. The semiconductor manufacturing apparatus according to claim 1, wherein the plurality of thermocouples are embedded in the heater, and the plurality of thermocouples are provided for correspondingly sensing temperatures near outer tubes of the plurality of zones. A first thermocouple provided, and a plurality of second cascades provided between the outer tube and the inner tube for sensing the temperatures of a plurality of zones in the reaction chamber in a corresponding manner. A semiconductor having a thermocouple, wherein the controller monitors a temperature in the reaction chamber based on an electromotive force of at least one of the first thermocouple and the second cascade thermocouple. Manufacturing equipment. 3. The semiconductor manufacturing apparatus according to claim 1, wherein the deposited film is a polysilicon film, and the etching gas is a ClF ₃ gas. 4. The semiconductor manufacturing apparatus according to claim 1, wherein the controller changes a radiant heat generated when the deposition film is removed by etching or a reaction between the etching gas and the deposition film. A semiconductor manufacturing apparatus, wherein an end point of etching removal of the deposited film is detected based on a change in electromotive force of the thermocouple due to a change in heat. 5. The semiconductor manufacturing apparatus according to claim 4, wherein the controller removes the deposited film by etching when the radiant heat and the reaction heat between ClF ₃ and the deposited film rise and then fall and become constant. A semiconductor manufacturing apparatus, wherein the determination is made as an end point of the semiconductor device. 6. The semiconductor manufacturing apparatus according to claim 1, wherein the controller detects a change in the heater control output to detect an end point of the etching removal of the deposited film. Characteristic semiconductor manufacturing equipment. 7. The semiconductor manufacturing apparatus according to claim 6, wherein the controller determines a point in time when the heater control output decreases and then increases and becomes constant as an end point of the etching removal of the deposited film. Semiconductor manufacturing equipment. 8. The semiconductor manufacturing apparatus according to claim 1, wherein the controller automatically proceeds to the next step after determining an end point of the etching removal of the deposited film, and performs a required process. A semiconductor manufacturing apparatus.