JP4385027B2 - Semiconductor manufacturing apparatus cleaning method, cleaning apparatus, and semiconductor manufacturing apparatus - Google Patents

Description

  The present invention relates to cleaning a member such as a wafer tray inside a semiconductor manufacturing apparatus. More specifically, the present invention relates to a method, a cleaning apparatus, and a semiconductor manufacturing apparatus for cleaning a member in an MOCVD apparatus for manufacturing a (III-V) nitride semiconductor by using hydrogen active species generated using a thermal catalyst. .

(III-V) nitride semiconductors are electronic materials expected in various fields such as light-emitting devices such as LEDs and electronic devices such as high-speed and high-power transistors. Among these, gallium nitride semiconductors have been put into practical use as blue LEDs and are now indispensable devices.
When manufacturing semiconductors, not limited to the above devices, how to make the manufacturing environment clean is one of the most fundamental and important factors in obtaining high-quality semiconductors and improving yield. One.

The utilization efficiency of the source gas in semiconductor manufacturing is low, and reaction products and surplus deposits (hereinafter collectively referred to as deposits) made of a nitride semiconductor are deposited not only on the substrate but also in the chamber. In particular, the MOCVD apparatus, which is an apparatus for manufacturing a (III-V) nitride semiconductor, is severely contaminated with deposits. In particular, there is a problem that deposits attached to the periphery of a reactor (reactor) such as a susceptor or a wafer tray are mixed into a semiconductor product due to peeling or the like, and the quality of the product is deteriorated.
In order to avoid quality degradation, parts are regularly replaced and cleaning is performed to remove deposits in the chamber.

Although there are various cleaning methods, there are roughly two types: dry cleaning and wet cleaning.
Generally, hydrochloric acid, sulfuric acid, hydrofluoric acid, etc. are used for wet cleaning of (III-V) nitride semiconductors, but reaction products and the like during the manufacture of gallium nitride compound semiconductors do not dissolve in these, so aqua regia Hot phosphoric acid is used.

  In the case of wet cleaning with aqua regia or hot phosphoric acid, phosphorous remains in the chamber, which adversely affects the quality of the semiconductor, is a strong acid, requires careful handling, and requires a waste liquid treatment facility. There is. In addition, aqua regia and hot phosphoric acid have a strong cleaning power and may damage parts. Therefore, soft cleaning capable of selective cleaning is desired.

In the case of dry cleaning, there is a method in which a cleaning gas containing fluorine or chlorine is supplied to generate plasma or to perform treatment at a high temperature using chlorine trifluoride having higher reactivity.
In addition, dry cleaning using hot hydrogen is also performed. The cleaning method using hot hydrogen is to remove deposits by bringing hydrogen into contact with a cleaning target heated to 1000 ° C. or higher.

  Dry cleaning with hot hydrogen does not have a problem like the wet cleaning described above. However, in this method, since the wafer tray is heated to a high temperature of 1000 ° C. or higher, the tray may be warped and deformed. The temperature distribution of the tray is an important parameter for the production of high-quality semiconductors. When the tray is warped, the temperature distribution changes, leading to a reduction in semiconductor quality and a reduction in growth reproducibility. Therefore, regular replacement of the tray is necessary, but in addition to the cost of replacement and labor cost of removing deposits, the total running cost such as re-examining the accurate temperature distribution of the replaced tray is reduced. Will be raised.

  In addition, a method of cleaning with a hydrogen active species using a thermal catalyst is also performed. For example, a method of forming a thin film including a step of generating hydrogen gas active species using a thermal catalyst and removing deposits, or generating a hydrogen gas active species using a thermal catalyst to generate reaction products and deposits. A PECVD apparatus having a mechanism for removing is known.

These prior arts all relate to a silicon semiconductor manufacturing apparatus using a PECVD apparatus. Thus, it was known that silicon could be etched with hydrogen atoms.
However, until now, there has been no example of applying cleaning with active species hydrogen generated using a thermal catalyst to a gallium nitride based semiconductor manufacturing apparatus.
This is because the growth temperature differs greatly between silicon-based semiconductors and gallium nitride-based semiconductors, and gallium nitride-based semiconductors are very strong in bonding, so that cleaning with conventional soft cleaning methods has been difficult.
JP 2004-43847 A JP 2004-149857 A Okumura et al., “Current Status and Issues of Nitride Semiconductor Application to Electronic Devices”, Vocabulary of Electronic Technology Research Institute, P.A. 153-159, Vol. 62, No. 10, 11 (1999)

  Accordingly, an object of the present invention relates to cleaning various members of a gallium nitride based semiconductor manufacturing apparatus, and is to obtain a cleaning method that can reliably remove deposits made of a nitride semiconductor and that does not damage the various members. .

To solve the above problem,
The invention according to claim 1 is a deposit made of a nitride semiconductor attached to a member used in a semiconductor manufacturing apparatus for manufacturing a (III-V) nitride semiconductor or in the semiconductor manufacturing apparatus. In the cleaning method of a semiconductor manufacturing apparatus, the temperature of the member is set to 600 to 900 ° C. when cleaning with the hydrogen active species generated by the thermal catalyst.

The invention according to claim 2 is the method for cleaning a semiconductor manufacturing apparatus according to claim 1, wherein the (III-V) nitride semiconductor is a gallium nitride based semiconductor.
The invention according to claim 3 is the method for cleaning a semiconductor manufacturing apparatus according to claim 1, wherein the catalyst temperature for generating hydrogen active species is 1650 to 1950 ° C.

Invention, prior to performing the cleaning by the hydrogen active species, cleaning method of a semiconductor manufacturing apparatus according to any three claims 1 and performs cleaning by the cleaning gas containing chlorine according to claim 4 It is.
According to a fifth aspect of the present invention, there is provided a cleaning device for a member used in a (III-V) nitride semiconductor manufacturing apparatus, a chamber and a thermal contact provided in the chamber for converting hydrogen into a hydrogen active species. A medium, a heater provided in the chamber and mounted on a member to be cleaned and heated to 600 to 900 ° C., an exhaust device for reducing the pressure in the chamber, and hydrogen in the chamber A cleaning device comprising a hydrogen supply source for supplying the gas.

The invention according to claim 6 includes a film forming apparatus that forms a thin film made of a nitride semiconductor on a substrate, a cleaning apparatus, and a glove box that connects the film forming apparatus and the cleaning apparatus.
The cleaning apparatus includes a chamber, provided in the chamber, a thermal catalyst for the hydrogen and hydrogen active species, provided in the chamber, by placing the member to be cleaned of the subject, this 600 to 900 A heater for heating to ° C., an exhaust device for reducing the pressure in the chamber, and a hydrogen supply source for supplying hydrogen into the chamber,
A member used in the film forming apparatus is transferred from the film forming apparatus to a cleaning device through a glove box, and the adhering material made of a nitride semiconductor adhering to the member is heated to 600 to 900 ° C. In addition, the semiconductor manufacturing apparatus is configured to be cleaned with hydrogen active species generated by the thermal catalyst and to return the cleaned member to the film forming apparatus through the glove box.

According to the cleaning method and apparatus of the present invention, active active species are generated by the reaction of the thermal catalyst and hydrogen, and the active species adheres to the inside of the semiconductor manufacturing apparatus or to various members constituting the semiconductor. The deposit consisting of is easily and reliably removed. Moreover, it is not necessary to expose the various members to a high temperature of 1000 ° C. or higher, and damage to the members can be prevented.
In the cleaning method of the present invention, cleaning with a gas containing chlorine is performed before cleaning with the hydrogen active species, whereby cleaning with a high shifting effect is possible. In addition, as in the present invention, it is very preferable to perform cleaning with active hydrogen species after using chlorine-containing gas because residual chlorine does not have to be taken into account.

  In addition, according to the semiconductor manufacturing method and apparatus of the present invention, it is possible to simultaneously form a thin film made of a nitride semiconductor and to remove deposits on a member such as a wafer tray, so that an efficient semiconductor device can be manufactured. It becomes.

  FIG. 1 shows an example of a cleaning apparatus according to the present invention, which is an apparatus for removing deposits adhering to a member such as a wafer tray used in a semiconductor manufacturing apparatus. In this apparatus, the operation of the semiconductor manufacturing apparatus is stopped, and the member taken out from the apparatus is cleaned.

  This apparatus includes a sealable chamber 1 in which cleaning is performed, a thermal catalyst 2 provided in the chamber 1, and a member 3 provided in the chamber 1 to be cleaned. Is composed of a heater 4 for heating the chamber 1, an exhaust device 5 for reducing the pressure in the chamber 1, and a hydrogen supply source 6 for supplying hydrogen into the chamber 1.

  The thermal catalyst 2 is made of a metal material such as tungsten, thorium, molybdenum, platinum, palladium, vanadium, or silicon, and has a coil shape or a mesh shape. Heated to ℃. The temperature of the thermal catalyst 2 can be measured with a radiation thermometer (not shown), and the temperature can be controlled by controlling the value of the current flowing through the thermal catalyst 2 according to the measured temperature. When the temperature of the thermal catalyst body 2 is less than 1500 ° C., the generation of hydrogen active species is insufficient, and when it exceeds 2000 ° C., the power consumption becomes very large and the life of the thermal catalyst body 2 decreases.

Further, an introduction port 7 for hydrogen from the hydrogen supply source 6 is formed in the vicinity of the thermal catalyst body 2, and the hydrogen fed into the chamber 1 from the introduction port 7 is a high temperature thermal catalyst body 2. When heated, it is heated and activated to become hydrogen active species, and this hydrogen active species removes the deposits adhering to the member 3.
Further, the positional relationship between the thermal catalyst body 2 and the member 3 is determined so that the distance between the thermal catalyst body 2 and the member 3 is about 50 mm.

  The cleaning method using this cleaning device is as follows. A member 3 to be cleaned, such as a wafer tray, is placed on the heater 4 and the exhaust device 5 is operated to bring the chamber 1 into a reduced pressure state of 1 to 100 Pa. Then, the heater 4 is energized to heat the member 3 to 600 to 900 ° C. When the temperature of the member 3 is less than 600 ° C., cleaning becomes insufficient, and when it exceeds 900 ° C., the member 3 is deformed by heat and is damaged or deteriorated. At the same time, the thermal catalyst 2 is energized and heated to 1500 to 2000 ° C. In this state, about 1 to 100 sccm of hydrogen from the hydrogen supply source 6 is supplied to the chamber 1 to generate hydrogen active species, and the member 3 is cleaned.

The cleaning time is not particularly limited and depends on the size of the target member 3 and the degree of adhesion of the adhered material, but it is 0.5 to 4 hours for a normal 8-inch wafer tray.
After performing the cleaning for a predetermined time, the energization to the heater 4 and the thermal catalyst 2 is stopped, the inside of the chamber 1 is cooled, and the operation is completed.

According to such a cleaning method, as will be apparent from specific examples described later, the deposits made of a nitride semiconductor such as GaN attached to the member 3 such as a wafer tray can be completely removed. For example, deposits made of GaN having a thickness of 3 to 5 μm can be removed by cleaning for 1 to 3 hours.
Further, even if the heating temperature of the target member 3 is less than 1000 ° C., the deposits can be removed, so that the member 3 is not damaged or deteriorated.

  Before performing such cleaning with hydrogen active species, the inside of the chamber is preferably heated to 500 to 1000 ° C., and a gas containing 0.1 to 50% chlorine is circulated. As a gas for diluting chlorine, it is preferable to use a gas that does not react with a chlorine-based gas such as nitrogen, hydrogen, helium, argon, or air. In the present invention, the cleaning with the hydrogen-containing species is performed after the cleaning with the chlorine-containing gas, so that the chlorine gas may have a low concentration, but the processing time may be shortened by increasing the concentration. Even if chlorine remains in the chamber by using a relatively high concentration of chlorine-containing gas, residual chlorine is removed during cleaning with the hydrogen active species, so the combined use of these two cleaning methods is very preferable.

FIG. 2 shows an example of a semiconductor manufacturing apparatus according to the present invention. In this example, a wafer tray is targeted as a member to be cleaned.
The manufacturing apparatus of this example is generally configured by a film forming apparatus 21, a cleaning apparatus 22, and a glove box 23 that connects the film forming apparatus 21 and the cleaning apparatus 22.

  The film forming apparatus 21 includes an upstream flow channel 211 for supplying a raw material gas for film formation, an intermediate flow channel 212 for film formation, and a downstream flow channel 213 for exhausting exhaust gas generated by the film formation. The intermediate flow channel 212 is provided with a disk-shaped wafer tray 214, a susceptor 215, and a heater 216, and a substrate 217 such as sapphire is placed on the wafer tray 214.

The cleaning device 22 has the same structure as that of the cleaning device shown in FIG. 1, and the same components are denoted by the same reference numerals and description thereof is omitted.
In addition, the glove box 23 that connects the film forming apparatus 21 and the cleaning apparatus 22 can move between the film forming apparatus 21 and the cleaning apparatus 22 of the wafer tray 214, and the substrate 217. It is configured so that it can be taken out to the outside.

  In addition, on-off valves 24 and 25 are inserted between the film forming apparatus 21 and the glove box 23 and between the cleaning apparatus 22 and the glove box 23, and it is necessary for gas to flow between both apparatuses. It can be blocked accordingly.

In this manufacturing apparatus, the film forming apparatus 21 forms a thin film made of a nitride semiconductor such as GaN on the substrate 217, and at the same time, the cleaning apparatus 22 attaches the deposit in the previous film forming process. The wafer tray 214 is cleaned.
Since the cleaning method of the wafer tray 214 is as described above, the description thereof is omitted.

Next, the cleaned wafer tray 214 is moved from the cleaning device 22 to the glove box 23, and a new substrate 217 is placed on the cleaned wafer tray 214. At the same time, the wafer tray 214 on which film formation has been completed is moved from the film formation apparatus 21 to the glove box 23, and the substrate 217 is taken out from the wafer tray 214.
Next, the wafer tray 214 from which the substrate 217 has been taken out is moved from the glove box 23 to the cleaning device 22, and at the same time, the cleaned wafer tray 214 on which the new substrate 217 is placed is sent from the glove box 23 to the film forming device 21.

The film forming apparatus 21 forms a thin film made of a nitride semiconductor on the new substrate 217, and the cleaning apparatus 22 cleans the wafer tray 214.
Thereafter, this operation is repeated, and film formation and cleaning are performed simultaneously in parallel.

In the present invention, in addition to the above-described embodiment, a thermal catalyst is provided in the film forming apparatus shown in FIG. 2 to supply hydrogen, and various members are cleaned inside the film forming apparatus. You may make it do.
In addition, two or more semiconductor film forming chambers are used, and in the same chamber, the semiconductor film forming and the cleaning of the inside of the chamber by the hydrogen active species generated by the thermal catalyst are alternately performed. During the cleaning, the semiconductor film may be formed using another chamber installed in parallel with the chamber.

  Further, the chamber has two or more chambers for film formation of semiconductors, and each chamber includes a thermal catalyst that generates hydrogen active species for cleaning the interior of the chamber, and performs semiconductor film formation and cleaning of the interior of the chamber. It is a chamber which can be implemented alternately, and the semiconductor may be continuously manufactured by switching each chamber.

Specific examples are shown below.
(Example 1)
Using the cleaning apparatus shown in FIG. 1, the 2.7 μm thick GaN film formed on the sapphire substrate was cleaned. As the thermal catalyst, a coil-shaped member formed by winding a tungsten wire was used, and was placed 50 mm away from the sapphire substrate. Hydrogen was introduced into the chamber at 50 sccm (50 cm 3 / min in terms of standard conditions) from a hydrogen supply source.

  The GaN film on the substrate was cleaned for 1 hour under conditions of a substrate temperature of 800 ° C., a thermal catalyst temperature of 1750 ° C., and a pressure of 50 Pa. From the scanning electron micrograph of the cross section of the GaN film after cleaning, it was found that the GaN film portion was almost removed by cleaning with hydrogen active species. Cleaning was possible under the same temperature conditions up to a pressure of about 10 Pa. However, it is better to extend the cleaning time at around 10 Pa.

(Example 2)
Next, the temperature dependence of the cleaning object in cleaning with hydrogen active species was confirmed. Under the pressure conditions as in Example 1, all of the GaN film is cleaned, so an experiment was conducted at a pressure of about 2.7 Pa as a condition for confirming temperature dependency. Other conditions are the same as in Example 1.
Table 1 shows the results of cleaning by changing the temperature of the sample substrate. Assuming that the film thickness of GaN before treatment is 1, the degree of removal by cleaning is represented by the removal rate.

  As shown in Table 1, the GaN film cannot be removed at 600 ° C., but if the temperature is higher than that, there is an effect of cleaning in the range of 1000 ° C. or less where no warping of the tray occurs. In particular, the removal rate was highest when the substrate temperature was around 800 ° C.

(Example 3)
Next, the temperature dependence of the thermal catalyst was confirmed. As in Example 2, the experiment was performed at a processing pressure of about 2.7 Pa where temperature dependence could be confirmed. The substrate temperature was 800 ° C., and other conditions were the same as in Example 1.
Table 2 shows the results of cleaning by changing the temperature of the sample substrate. Similar to Table 1, the film thickness of the GaN film before treatment was set to 1, and the degree of removal by cleaning was represented by the removal rate.

  As shown in Table 2, if the thermal catalyst is 1600 to 2000 ° C., there is a cleaning effect. In particular, the removal rate was highest when the temperature of the thermal catalyst was around 1850 ° C.

(Example 4)
Examination of a scanning electron microscope cross-sectional photograph of the substrate when the substrate temperature was heated to 1000 ° C. or more, which was a conventional method, and the GaN film was cleaned with hydrogen, the GaN film remained. In addition to the above, it was found that cloud-like objects were deposited on the surface. This cloud-like material is considered as a residue that cannot be removed by the above-described hot hydrogen treatment, and needs to be physically removed.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chamber 2 ... Thermal catalyst body 3 ... Member 4 ... Heater 5 ... Exhaust device 6 ... Hydrogen supply source 21 ... Film forming device 22 ... Cleaning device

Claims (6)

(III-V) Hydrogen generated by a thermal catalyst in the semiconductor manufacturing apparatus for manufacturing a nitride semiconductor or deposits made of a nitride semiconductor attached to a member used in the semiconductor manufacturing apparatus A cleaning method of a semiconductor manufacturing apparatus , wherein the temperature of the member is set to 600 to 900 ° C. when cleaning with active species.   2. The method of cleaning a semiconductor manufacturing apparatus according to claim 1, wherein the (III-V) nitride semiconductor is a gallium nitride based semiconductor. The method for cleaning a semiconductor manufacturing apparatus according to claim 1, wherein the catalyst temperature for generating hydrogen active species is 1650 to 1950 ° C. 4. The method for cleaning a semiconductor manufacturing apparatus according to claim 1, wherein cleaning is performed with a cleaning gas containing chlorine before the cleaning with the hydrogen active species . A cleaning device for a member used in a (III-V) nitride semiconductor manufacturing apparatus, which is provided in a chamber, a thermal catalyst provided in the chamber, for converting hydrogen into a hydrogen active species, and in the chamber A heater for mounting a member to be cleaned and heating the member to 600 to 900 ° C., an exhaust device for reducing the pressure in the chamber, and a hydrogen supply source for supplying hydrogen into the chamber A cleaning device characterized by that. A film forming apparatus and a cleaning apparatus for forming a thin film made of a nitride semiconductor on a substrate, and a glove box for connecting the film forming apparatus and the cleaning apparatus are provided.
The cleaning device is provided with a chamber, a thermal catalyst for providing hydrogen as a hydrogen active species, and a member to be cleaned, which is provided in the chamber. A heater for heating to ° C., an exhaust device for reducing the pressure in the chamber, and a hydrogen supply source for supplying hydrogen into the chamber,
A member used in the film forming apparatus is transferred from the film forming apparatus to a cleaning device through a glove box, and the adhering material made of a nitride semiconductor adhering to the member is heated to 600 to 900 ° C. In addition, the semiconductor manufacturing apparatus is configured to perform cleaning with active hydrogen species generated by the thermal catalyst, and to return the cleaned member to the film forming apparatus through the glove box .

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