JP5498640B2 - Method and apparatus for cleaning nitride semiconductor manufacturing equipment parts - Google Patents

Description

  In the present invention, when a component such as a wafer tray constituting a nitride semiconductor manufacturing apparatus for manufacturing a nitride semiconductor such as gallium nitride (GaN) or gallium aluminum nitride (AlGaN) is contaminated with a nitride semiconductor, this component The present invention relates to a method and an apparatus for cleaning.

A nitride semiconductor manufacturing apparatus (hereinafter referred to as “semiconductor manufacturing apparatus”) manufactures a semiconductor by depositing a nitride such as GaN or AlGaN on a wafer, and in this process, the semiconductor is manufactured on the wafer in the semiconductor manufacturing apparatus. A semiconductor thin film such as GaN to be deposited adheres to various parts other than the wafer, such as a wafer tray and a gas flow path for holding the wafer.
A semiconductor thin film such as GaN adhering to parts other than the wafer becomes an unnecessary contaminant and obstructs the manufacture of the nitride semiconductor. Therefore, it is necessary to appropriately remove the contaminant by washing the contaminated part.

As a cleaning method for this contaminated part, hydrogen cleaning and phosphoric acid cleaning are usually performed in parallel.
The hydrogen cleaning mainly removes contaminants attached to the wafer tray, and is performed by venting hydrogen into the semiconductor manufacturing apparatus while holding the wafer tray at a high temperature of 1000 ° C. or higher. The reason why the temperature is set to 1000 ° C. or higher is to volatilize and remove the reaction product of contaminants and hydrogen.

  Phosphoric acid cleaning removes contaminants adhering to the flow channels and the like that constitute the gas flow path. Remove the flow path forming parts such as the flow channel from the semiconductor manufacturing apparatus and place the flow path forming parts in another place. It is immersed and washed in heated phosphoric acid.

Japanese Patent Laid-Open No. 6-124894 discloses a cleaning method in which a contaminated part is housed in a cleaning chamber, a cleaning gas of halogen-based gas and argon is introduced, plasma is generated in the cleaning chamber, and contaminants are removed. It is disclosed.
Japanese Unexamined Patent Publication No. 20002-164335 discloses the removal of contaminants mainly composed of silicon oxide.
JP 2002-164335 A JP-A-6-124894

However, since the wafer tray is kept at a high temperature of 1000 ° C. or higher in the hydrogen cleaning, there is a fear that the wafer tray is thermally deformed. On the other hand, in the phosphoric acid cleaning, the worker is dangerous because the cleaning is performed under a toxic phosphoric acid vapor.
Also, in the method of cleaning with halogen gas and argon cleaning gas in a plasma state, halogen-based material may remain in the cleaned parts, and this residual halogen-based material corrodes semiconductor manufacturing equipment parts and is normal. There is a risk of obstructing the production of a semiconductor.

  Therefore, the problem in the present invention is that when various parts constituting the semiconductor manufacturing apparatus are contaminated with the contaminants when manufacturing the nitride semiconductor, the contaminated parts do not cause damage or corrosion of the parts. In addition, the object is to obtain a cleaning method and a cleaning device that allow an operator to work safely.

To solve this problem,
The invention according to claim 1 is a mixed gas obtained by diluting chlorine in a reaction chamber made of silica in a nitride semiconductor manufacturing apparatus in a nitride semiconductor manufacturing apparatus in which a component contaminated with a contaminant made of GaN or AlGaN is a nitride semiconductor. The first cleaning gas is contacted at 500 to 1000 ° C. to remove the pollutant , and the second gas which is a mixed gas of hydrogen gas and dilution gas with respect to the chlorine-based material remaining in the component This is a method for cleaning a nitride semiconductor manufacturing apparatus component, characterized in that the cleaning gas is removed by bringing the cleaning gas into contact at 500 to 1000 ° C. for reaction .

The chlorine gas concentration of the first cleaning gas is preferably 5% by volume or more .
The invention according to claim 2 is characterized in that the contact with the first cleaning gas and the contact with the second cleaning gas are performed by a batch processing method. This is a cleaning method.

The invention according to claim 3 is characterized in that the contact with the first cleaning gas and the contact with the second cleaning gas are performed by an aeration treatment method. This is a cleaning method .
Such invention in claim 4, wherein the contact between the second cleaning gas with contaminated components, according to any one of claims 1 to 3, characterized in that is carried out at 500 to 1000 ° C. This is a cleaning method for parts of the nitride semiconductor manufacturing apparatus.

The invention according to claim 5 is a reaction chamber made of silica having a first cleaning gas introduction pipe, a second cleaning gas introduction pipe, and an exhaust gas discharge pipe ,
Heating means capable of maintaining a cleaning target part contaminated with a contaminant made of GaN or AlGaN as a nitride semiconductor in a nitride semiconductor manufacturing apparatus housed in the reaction chamber at a temperature of 500 to 1000 ° C . ;
A first cleaning gas supply source that feeds into the first cleaning gas introduction pipe a first cleaning gas that is a mixed gas obtained by diluting chlorine that is in contact with the cleaning target component at 500 to 1000 ° C. with nitrogen ;
A second cleaning gas that is a mixed gas of hydrogen gas and dilution gas that reacts and is removed by contacting the second cleaning gas introduction pipe with a chlorine-based substance remaining in the cleaning target component at 500 to 1000 ° C. And a second cleaning gas supply source for feeding a nitride semiconductor manufacturing apparatus component cleaning apparatus.

According to the method of the present invention, the contaminated contaminants react with the chlorine-based gas contained in the first cleaning gas to produce a reaction product, which is generated at a temperature of 500 ° C. or higher. Vaporizes immediately, which removes contaminants and cleans contaminated parts. Thereafter, when the part comes into contact with the second cleaning gas, the chlorine-based substance remaining in the part is removed, and the chlorine-based substance does not remain in the part.
Moreover, since it is not necessary to use a high temperature of 1000 ° C. or higher unlike conventional hydrogen cleaning, parts such as a wafer tray are not thermally deformed, and cleaning is not performed in a toxic environment such as conventional phosphoric acid cleaning. Therefore, the safety of workers can be ensured.
In addition, the method of the present invention has an advantage that the cleaning can be performed by one cleaning method as compared with the conventional method using two types of cleaning methods.

  Further, according to the apparatus of the present invention, the first and second cleaning gases and the contaminated parts are cleaned in the sealed space in the reaction chamber, so that the worker can perform the cleaning operation safely. .

FIG. 1 shows an example of the cleaning apparatus of the present invention.
The cleaning apparatus of this example includes a reaction chamber 1 made of a heat-resistant material such as silica that houses contaminated parts, and a first cleaning gas introduction pipe 2 that introduces a first cleaning gas into the reaction chamber 1. Similarly, the second cleaning gas introduction pipe 3 for introducing the second cleaning gas into the reaction chamber 1, the exhaust gas discharge pipe 4 for exhausting the exhaust gas generated in the reaction chamber 1, and the reaction chamber 1 within 500 ° C. A pair of heaters 5 and 5 (heating means) that can be maintained at a temperature of 1000 ° C., and the temperature of the contaminated parts stored in the reaction chamber 1 by adjusting the outputs of the heaters 5 and 5 are in the range of 500 to 1000 ° C. A temperature controller 6 that is kept constant is provided, and a base 8 on which a contaminated component 7 to be cleaned is placed is disposed at the bottom of the reaction chamber 1.

  The first cleaning gas is supplied from a container 9 filled with a chlorine-based gas such as chlorine or hydrogen chloride and a container 10 filled with a dilution gas, and the two gases are appropriately mixed by the flow control valves 11 and 11 to form the first cleaning gas. It becomes a cleaning gas, passes through the gas introduction valves 16 and 16, and is introduced into the reaction chamber 1 through the first cleaning gas introduction pipe 2.

  The second cleaning gas is supplied from a container 12 filled with a hydrogen-based gas such as hydrogen or methane and a container 13 filled with a diluent gas, and the two cleaning gases are appropriately mixed by the flow rate control valves 14 and 14. Then, the gas passes through the gas introduction valves 16 and 16 and is introduced into the reaction chamber 1 through the second cleaning gas introduction pipe 3.

Further, the exhaust gas discharge pipe 4 is connected to a vacuum pump 15 via a discharge valve 17 so that the inside of the reaction chamber 1 can be brought into a vacuum reduced pressure state. Further, the vacuum pump 15 is connected to an exhaust gas abatement treatment apparatus (not shown) so that various gases discharged from the reaction chamber 1 are rendered harmless and then discharged into the atmosphere.
The heater 5 may be anything as long as it can heat contaminated parts such as heating wires and lamp heating, and the number is not limited to two and may be arbitrary.

Next, a method for cleaning contaminated parts using this cleaning apparatus will be described. The cleaning method of the present invention includes a batch processing method and an aeration processing method. First, a description will be given of the batch processing method.
As will be described later, the batch processing method means that the first cleaning gas is sealed in the reaction chamber 1 for a predetermined time, then the gas in the reaction chamber 1 is purged, and then the second cleaning gas is supplied for a predetermined time. The reaction is performed in an enclosed state.
First, after removing the contaminated component 7 from the semiconductor manufacturing apparatus and placing it on the base 8 of the reaction chamber 1, the reaction chamber 1 is sealed.

  Next, after the heater 4 is operated to heat the contaminated parts in the reaction chamber 1 to a temperature of 500 to 1000 ° C., the vacuum pump 17 is operated to reduce the pressure in the reaction chamber 1, and then the discharge valve 17 is closed. Then, the gas introduction valves 16 and 16 are opened to introduce the first cleaning gas into the reaction chamber 1 from the first cleaning gas introduction pipe 2. Thereafter, the gas introduction valves 16 and 16 are closed, and the first cleaning gas is sealed in the reaction chamber 1.

As the first cleaning gas at this time, a mixed gas obtained by diluting a chlorine-based gas with a diluent gas is used. Chlorine-based gases include chlorine in molecules such as Cl ₂ (chlorine), HCl, SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₃ Cl, BCl ₃ , CHCl ₃ , CH ₂ Cl ₂ , and CH ₃ Cl. One kind or a mixture of two or more kinds of compounds is used, and chlorine is particularly preferable in consideration of price, reactivity and the like.

  As the dilution gas, one or a mixture of two or more kinds of arbitrary gases that do not react with a chlorine-based gas such as nitrogen, helium, argon, and air can be used. The chlorine-based gas concentration in the first cleaning gas is 5% by volume or more. Even if the chlorine-based gas concentration is less than 5% by volume, the contaminants react with the chlorine-based gas in the first cleaning gas, but the reaction rate becomes slow and the practicality becomes poor.

  On the other hand, if the chlorine-based gas concentration is too high, the parts themselves may be corroded, but the amount of gas to be filled is small, and the higher the chlorine-based gas concentration, the higher the cleaning performance. Therefore, 100% by volume is preferable. .

  At this time, the reason why the contaminated parts are brought into contact at a temperature of 500 ° C. or more is to vaporize and discharge the reaction product generated by the reaction between the contaminant and the first cleaning gas. Although the reaction product can be vaporized even at a temperature lower than 500 ° C., the volatilization rate is slow, so that it is not practical as a cleaning method. In addition, the temperature at the time of contact is set to 1000 ° C. or lower because it is determined from the viewpoint of preventing thermal deformation of the contaminated component. If the component does not cause thermal deformation even at a temperature of 1000 ° C. or higher, the temperature is 1000 ° C. or higher. Anyway.

  When the first cleaning gas is sealed for a predetermined time, the contaminants attached to the contaminated parts react with the chlorine-based gas contained in the first cleaning gas to produce a reactant, but this reactant is immediately evaporated. It becomes volatile exhaust gas and drifts in the reaction chamber 1.

  Thereafter, the discharge valve 17 is opened and the first cleaning gas and the exhaust gas are discharged from the exhaust gas discharge pipe 4. Then, the vacuum pump 15 is operated again, the inside of the reaction chamber 1 is reduced, and the discharge valve 17 is closed. Next, the gas introduction valves 16 and 16 are opened, and the second cleaning gas is introduced into the reaction chamber 1 from the second cleaning gas introduction pipe 3 and sealed.

  As the second cleaning gas, a mixed gas of a hydrogen-based gas containing hydrogen in a molecule such as hydrogen, methane, or ethane and a dilution gas composed of an inert gas such as argon, helium, or nitrogen that dilutes the gas is used. . As the hydrogen-based gas, hydrogen is most preferable in terms of reactivity.

The concentration of the hydrogen-based gas in the second cleaning gas is 10 to 100% by volume, and if it is less than 10% by volume, the chlorine-based gas remaining in the part cannot be sufficiently removed. On the other hand, the higher the hydrogen-based gas concentration, the higher the cleaning performance, so 100% by volume is preferable.
The contact temperature between the second cleaning gas and the component is in the range of 500 to 1000 ° C. If the temperature is less than 500 ° C., the remaining chlorine-based material is not sufficiently removed, and if the temperature exceeds 1000 ° C., the component is thermally deformed. Produce.

  Due to the contact between the second cleaning gas and the component, the chlorine-based substance resulting from the chlorine-based gas remaining on the component at the time of the contact with the first cleaning gas is the second cleaning gas. It reacts with the hydrogen-based gas therein and becomes hydrogen chloride gas or the like and is removed from the parts. This hydrogen chloride gas or the like drifts in the reaction chamber 1. Thereafter, the discharge valve 17 is opened, and the second cleaning gas and hydrogen chloride gas are discharged from the exhaust gas discharge pipe 4. Subsequently, nitrogen etc. are introduce | transduced in the reaction chamber 1, and components are cooled to room temperature.

Next, the cleaning method by the aeration treatment method of the present invention will be described.
This aeration treatment method is a method in which the first cleaning gas continues to flow into the reaction chamber 1 for a predetermined time, and then the second cleaning gas continues to flow for a predetermined time. The first and second cleaning gases used in this method are the same as those in the previous batch processing method, and the reaction temperature and reaction time may be the same in principle.

  First, the contaminated part 7 is placed on the base 8 of the reaction chamber 1 and the reaction chamber 1 is sealed. Next, the vacuum pump 15 is operated to purge the gas in the reaction chamber 1. After that, the heaters 5 and 5 are actuated to set the temperature of the contaminated component 7 in the reaction chamber 1 to 500 to 1000 ° C., and the first cleaning gas is introduced into the reaction chamber 1 from the first cleaning gas introduction pipe 2 in a predetermined manner. Continue to flow for a predetermined time at the flow rate.

  Due to the introduction of the first cleaning gas, the contaminants adhering to the component 7 react with the chlorine-based gas contained in the first cleaning gas, become volatile exhaust gas, and leave the component 7. The exhaust gas is accompanied by the first cleaning gas and is discharged from the reaction chamber 1 through the exhaust gas discharge pipe 4 to the outside of the system.

After flowing the first cleaning gas for a predetermined time, the introduction of the first cleaning gas is stopped, and at the same time, the second cleaning gas starts to flow from the second cleaning gas introduction pipe 3 into the reaction chamber 1. The temperature of the components at this time is set to 500 to 1000 ° C.
After flowing the second cleaning gas for a predetermined time, the introduction of the second cleaning gas is stopped.

  By introducing the second cleaning gas, the chlorine-based substance adhering to the component reacts with the hydrogen in the hydrogen-based gas and becomes hydrogen chloride gas, etc., and leaves the component. This gas is discharged from the exhaust gas exhaust pipe 4. Discharged. Next, nitrogen or the like is introduced into the reaction chamber 1 to cool the part 7 to room temperature.

Thus, in the cleaning method of the present invention, contaminants made of nitride semiconductor such as GaN adhering to the component are removed by introducing the first cleaning gas, and adhering to the component by introducing the second cleaning gas. As a result, the remaining chlorine-based material is removed.
For this reason, the chlorine-based substance does not remain in the part, and the part is not corroded by the chlorine-based substance.
Furthermore, the chlorine-based substance is scattered from the components and is not mixed into the film at the time of forming the nitride semiconductor, and a high-quality nitride semiconductor film can be obtained.

  In the cleaning method of the present invention, the first and second cleaning gases may be introduced into the semiconductor manufacturing apparatus itself, but it is necessary to prevent damage to the apparatus itself.

Specific examples are shown below, but the present invention is not limited thereto.
A cleaning apparatus having the configuration shown in FIG. 1 was used.
As the reaction chamber, a cylindrical chamber having an internal size of 30 cm in diameter and 100 cm in width was used, and the first cleaning gas and the second cleaning gas were introduced. As a simulation sample, a gallium nitride or gallium aluminum nitride crystal film having a known thickness was formed on a sapphire substrate.

(Example 1, batch processing method)
A sapphire substrate on which a GaN crystal having a thickness of 3.0 μm was formed was placed in a reaction chamber, and the temperature was raised while supplying 42 slm of nitrogen. After the temperature in the reaction chamber reached 800 ° C., the introduction of nitrogen was stopped and the pressure in the reaction chamber 1 was reduced, and then 70 liters of chlorine was sealed and the treatment was performed for 0.5 hour. Thereafter, the sealed gas was discharged, and nitrogen 42 slm was flowed, and the reaction chamber was cooled to room temperature.
As a result of taking out the sapphire substrate and measuring the GaN film thickness before and after the treatment by SEM, all of the GaN film was removed, and only the sapphire substrate remained.

Then, the chlorine atom concentration remaining on the surface of the sapphire substrate was measured with an X-ray photoelectron spectrometer (XPS) and found to be 1.5 atomic%.
Further, this sapphire substrate was returned to the reaction chamber, and the reaction was carried out at a temperature of 800 ° C. for 0.5 hours with 70 liter of hydrogen as the sealing gas, and then cooled to room temperature.
When the chlorine atom concentration remaining on the surface of the sapphire substrate was measured in the same manner, it was 0.1 atomic% or less (ND).

(Example 2, batch processing method)
A sapphire substrate on which an AlGaN crystal having a thickness of 1.0 μm was formed was placed in the reaction chamber, and the temperature was raised while supplying 42 slm of nitrogen. After the reaction chamber temperature reached 800 ° C., the introduction of nitrogen was stopped, and after the reaction chamber was evacuated, 70 liters of hydrogen chloride was sealed and the treatment was performed for 0.5 hour. Thereafter, after the sealed gas was discharged, 42 slm of nitrogen was flowed, and the reaction chamber was cooled to room temperature.
As a result of taking out the sapphire substrate and measuring the AlGaN film thickness before and after the treatment by SEM, all of the AlGaN film was removed, and only the sapphire substrate remained.

Next, the chlorine atom concentration remaining on the surface of the sapphire substrate was measured with an X-ray photoelectron spectrometer (XPS), and found to be 0.80 atomic%.
Further, this sapphire substrate was returned to the reaction chamber, and the reaction gas was reacted at a temperature of 800 ° C. for 0.5 hours with 70 liter of hydrogen gas, and then cooled to room temperature.
When the chlorine atom concentration remaining on the surface of the sapphire substrate was measured in the same manner, it was 0.1 atomic% or less (ND).

(Example 3, ventilation method)
A sapphire substrate on which a GaN crystal having a thickness of 3.0 μm was formed was placed in a reaction chamber, and the temperature was raised while supplying 42 slm of nitrogen. After the temperature in the reaction chamber reached 800 ° C., the treatment was performed for 0.5 hour with the introduced gas as nitrogen 21 slm + chlorine 21 slm (chlorine gas concentration 50 vol%). Thereafter, the introduced gas was changed to 42 slm, and the reaction chamber was cooled to room temperature.
As a result of taking out the sapphire substrate and measuring the GaN film thickness before and after the treatment by SEM, all of the GaN film was removed, and only the sapphire substrate remained.

Subsequently, the chlorine atom concentration remaining on the surface of the sapphire substrate was measured with an X-ray photoelectron spectrometer (XPS), and found to be 1.4 atomic%.
Furthermore, this sapphire substrate was returned to the reaction chamber, and the introduced gas was nitrogen 21 slm + hydrogen 21 slm (hydrogen-based gas concentration 50 vol%) for 0.5 hour at a temperature of 800 ° C., and then cooled to room temperature.
When the chlorine atom concentration remaining on the surface of the sapphire substrate was measured in the same manner, it was 0.1 atomic% or less (ND).

(Conventional example 1)
A GaN crystal having a thickness of 3.0 μm formed on a sapphire substrate was placed in the reaction chamber, and the temperature was raised while supplying 42 slm of nitrogen. After the reaction chamber temperature reached 900 ° C., the introduced gas was treated with hydrogen 42 slm for 1.0 hour. Thereafter, the introduced gas was returned to 42 slm of nitrogen, and the reaction chamber was cooled to room temperature.
As a result of taking out the sapphire substrate and measuring the processed GaN film thickness with SEM, the film thickness was 3.0 μm and GaN could not be removed.

(Conventional example 2)
Quartz glass with a diameter of 5 cm on which a GaN crystal was formed was placed in the reaction chamber, and the temperature was raised while supplying 42 slm of nitrogen. After the reaction chamber temperature reached 1000 ° C., the introduced gas was changed to hydrogen 42 slm, and the treatment was performed for 1.0 hour. Thereafter, the introduced gas was returned to 42 slm of nitrogen, and the reactor was cooled until the temperature in the reactor reached room temperature. After performing this treatment 30 times, the warp of the quartz glass was measured, and as a result, a warp of 150 microns was observed.

  Comparing Example 1 in the batch processing method and Example 3 in the aeration processing method, the amount of chlorine used is 70 liters in Example 1, whereas in Example 3, 21 slm × 30 minutes = 630 liters. In the batch processing method, the amount of chlorine gas used can be reduced to 1/9 that of the aeration processing method.

It is a schematic block diagram which shows an example of the washing | cleaning apparatus of this invention.

Explanation of symbols

1 ... Reaction chamber 2 ... First cleaning gas introduction pipe 3 ... Second cleaning gas introduction pipe 3 ... Exhaust gas discharge pipe 5 ... Heater 9 ... Container 10 ... Container 11. Flow control valve

Claims (5)

In a nitride semiconductor manufacturing apparatus, a part contaminated with contaminants composed of GaN or AlGaN, which is a nitride semiconductor , is mixed with a first cleaning gas, which is a mixed gas obtained by diluting chlorine with nitrogen in a silica reaction chamber. Contact at 500-1000 ° C. to remove the contaminants ,
The second cleaning gas, which is a mixed gas of hydrogen gas and diluent gas, is removed from the chlorine-based substance remaining in the component by contacting it at 500 to 1000 ° C. to cause a reaction. Method for cleaning nitride semiconductor manufacturing equipment parts.   2. The method for cleaning a nitride semiconductor manufacturing apparatus component according to claim 1, wherein the contact with the first cleaning gas and the contact with the second cleaning gas are performed by a batch processing method.   2. The method for cleaning a nitride semiconductor manufacturing apparatus component according to claim 1, wherein the contact with the first cleaning gas and the contact with the second cleaning gas are performed by an aeration process.   4. The nitride semiconductor manufacturing apparatus component according to claim 1, wherein the contact between the second cleaning gas and the contaminated component is performed at 500 to 1000 ° C. 5. Cleaning method. A silica reaction chamber having a first cleaning gas introduction pipe, a second cleaning gas introduction pipe and an exhaust gas discharge pipe ;
Heating means capable of maintaining a cleaning target part contaminated with a contaminant made of GaN or AlGaN as a nitride semiconductor in a nitride semiconductor manufacturing apparatus housed in the reaction chamber at a temperature of 500 to 1000 ° C . ;
A first cleaning gas supply source that feeds into the first cleaning gas introduction pipe a first cleaning gas that is a mixed gas obtained by diluting chlorine that is in contact with the cleaning target component at 500 to 1000 ° C. with nitrogen ;
A second cleaning gas that is a mixed gas of hydrogen gas and dilution gas that reacts and is removed by contacting the second cleaning gas introduction pipe with a chlorine-based substance remaining in the cleaning target component at 500 to 1000 ° C. And a second cleaning gas supply source for feeding a nitride semiconductor manufacturing apparatus component cleaning apparatus.

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