JP2007067422A - Film-forming processor and cleaning method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clean undesired coats adhered to each portion during film formation in every corner in a processing container in a film-forming processor. <P>SOLUTION: In a film forming step, the most of the decomposition product or the reaction product of reaction gas is deposited on the surface of semiconductor wafer 14. A part thereof is adhered to the outer periphery portion of a susceptor 12 and a wafer holding member. It is adhered also to the inner wall surface of a processing container 10 in a small amount. When the film forming step is carried out predetermined times, purging using H2 gas, N2 gas, or the like is carried out in a state in which there is no semiconductor wafer 14 in the processing container 10. After the completion of a purging step, a cleaning step is carried out. In the cleaning step, cleaning gas in which CIF3 gas is diluted to predetermined density using N2 gas is supplied from a perforated plate 18 to the processing container 10 by a cleaning gas supply system 24. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cold wall type film forming apparatus and a cleaning method thereof.

  The CVD equipment used in the film formation process of semiconductor integrated circuits is a hot wall type that heats the semiconductor wafer by placing the entire processing vessel in an electric furnace, and heats the semiconductor wafer without affecting the temperature of the processing vessel. It is divided into a cold wall shape. In general, the hot wall type is used for batch processing for forming a large number of semiconductor wafers at a time, whereas the cold wall type is used for single wafer processing for forming semiconductor wafers one by one.

  In a cold wall type CVD apparatus, a semiconductor wafer is set on a susceptor (substrate mounting table), and the semiconductor wafer is heated through an appropriate heater through the susceptor, or directly exposed to light from outside without passing through the susceptor. Meanwhile, a predetermined gas is supplied to the surface of the semiconductor wafer, and a decomposition product or a reaction product of the gas is deposited on the wafer. When a film is formed on the semiconductor wafer in this way, reaction gas decomposition products or reaction products are deposited on the surface of the susceptor, wafer holding means, etc. around the semiconductor wafer, and the film adheres. In addition, such a film may adhere to the inner wall surface of the processing container.

Conventionally, as a method of cleaning the inside of a cold wall type CVD apparatus, a cleaning gas containing NF3 is supplied into the apparatus, and the film adhering to the susceptor or wafer holding means as described above is removed by etching with this cleaning gas. There is a known method (for example, see Patent Document 1). In this cleaning method, since NF3 itself is not degradable, plasma is used. That is, an electrode plate is disposed at a position facing the susceptor in the processing container, a high frequency voltage is applied between the susceptor and the electrode plate, plasma is generated there, and NF3 is excited to an active state by the plasma. I am doing so.
Japanese Patent Laid-Open No. 3-47968

  The NF3 plasma cleaning method as described above can effectively remove the film on the susceptor surface side and wafer holding means surface side in contact with the plasma, but removes the film on the susceptor back side where the plasma does not reach. could not. In addition, since plasma is used, there is a restriction that it cannot be implemented in a cold wall forming film processing apparatus that cannot generate plasma in a processing container.

  Also, from the viewpoint of exhaust gas regulation, it is customary to attach an expensive removal device for decomposing and removing harmful and dangerous gas components from exhaust gas in the CVD apparatus, but NF3 is a gas that is difficult to decompose. Therefore, a common removal device cannot be used with other exhaust gases such as a reaction gas, and a separate removal device is required separately. For this reason, two removal devices have to be installed.

  The present invention has been made in view of such problems, and can effectively clean an undesired film attached to each part during film formation to every corner of the processing apparatus and requires a special removal apparatus. It is an object of the present invention to provide a film forming apparatus and a cleaning method for the film forming apparatus.

  In order to achieve the above object, a film forming apparatus of the present invention includes a processing container capable of being evacuated, a substrate mounting table for mounting a substrate to be processed in the processing container, and an installation for heating the substrate mounting table. A base heating means, a processing gas supply means for supplying a processing gas for film formation in the film forming process step into the processing container through a perforated plate facing the substrate mounting table, and a ClF3 gas in the cleaning process. Cleaning gas supply means for supplying the processing container through a plate, and in the cleaning step, the cleaning gas supply means in a state where the substrate setting table is heated within the range of the corrosion resistance temperature by the setting table heating means. The ClF3 gas is supplied into the processing container, and the film adhering to the substrate mounting table is removed.

  Further, the cleaning method of the film processing apparatus according to the present invention includes a processing container capable of being evacuated, a substrate mounting table for mounting a substrate to be processed in the processing container, and a mounting table heating means for heating the substrate mounting table, In a film forming apparatus having a processing gas supply means for supplying a processing gas for film formation into the processing container through a perforated plate facing the substrate mounting base in the film forming processing step, the mounting base heating means In a state where the substrate mounting table is heated within the range of the corrosion resistant temperature, a cleaning gas supply means supplies ClF3 gas to the processing container through the perforated plate to remove the film adhering to the substrate mounting table. It is characterized by that.

  In the present invention, a single-wafer type film forming process (a substrate mounting table on which a substrate to be processed is mounted in a processing container is heated by a setting table heating means in the processing container of the film forming processing apparatus, After the reaction gas is introduced from the perforated plate to form a film on the substrate to be processed, the inside of the processing container is cleaned. In this cleaning, a cleaning gas containing ClF3 is supplied into the processing vessel through the perforated plate while heating the substrate mounting table within the range of the corrosion resistance temperature by the substrate mounting table heating means. At that time, plasma is not used. Since ClF3 gas is very active, it reacts easily with the coating at temperatures within the range of corrosion resistance temperature. That is, when a part of ClF3 gas reacts to generate reaction heat, the reaction heat activates nearby ClF3 gas and reacts, and the reaction heat activates more ClF3 gas to react. The etching is developed spontaneously.

  As a preferred embodiment of the present invention, the material of the substrate mounting table includes aluminum nitride, quartz, silicon carbide, or alumina.

  Moreover, the film forming apparatus of the present invention has a wall heating means for heating the wall of the processing container as a preferred aspect, and the wall of the processing container is within the range of the corrosion resistance temperature by the wall heating means in the cleaning process. Heat. In this case, the wall heating means is preferably constructed by burying the heat generating means in the wall of the processing vessel, and aluminum can be suitably used as the wall material.

  In another preferred embodiment, a gas introduction pipe for introducing a processing gas and a cleaning gas is connected to the processing container, a processing gas supply system for supplying the processing gas to the gas introduction pipe, and a cleaning gas supply for supplying the cleaning gas. The system is connected. The supply of the processing gas to the processing container and the supply of the cleaning gas are switched by opening / closing valves provided in the processing gas supply system and the cleaning gas supply system.

  According to the film forming apparatus or the cleaning method of the film forming apparatus of the present invention, the above-described configuration and operation effectively remove an undesired film attached to each part during film formation to every corner in the processing apparatus. It can be cleaned and a special removal device can be dispensed with.

  Hereinafter, an embodiment in which the present invention is applied to a cold-wall type single-wafer CVD apparatus will be described with reference to the accompanying drawings.

  In FIG. 1, a processing container 10 of this CVD apparatus is a cylindrical chamber made of, for example, aluminum, and a susceptor (substrate mounting table) 12 is disposed at the center thereof. When the film forming process is performed, the semiconductor wafer 14 is placed on the susceptor 12 as indicated by a dotted line. A gate valve 16 is provided on one side wall of the processing container 10, and the semiconductor wafer 14 is taken in and out through the gate valve 16.

  A perforated plate 18 for uniformly supplying gas is attached above the susceptor 12, and a gas discharge portion 20 a of the gas introduction pipe 20 is vertically placed in the container from the back (upper part) of the perforated plate 18. . A reaction gas supply system 22 and a cleaning gas supply system 24 are connected to the gas introduction pipe 20, and these are switched by valves 26 and 28.

  The cleaning gas supply system 24 includes a ClF3 gas supply unit 30 for supplying ClF3 as an etching gas and an N2 gas supply unit 32 for supplying N2 gas as a dilution carrier gas. Are connected to the gas introduction pipe 20 via gas flow regulators (MFC) 34, 36 and valves 38, 40, respectively. The supply flow rates of ClF3 gas and N2 gas are adjusted by the gas flow rate regulators 34 and 36, whereby the cleaning gas in which ClF3 is diluted to a predetermined concentration is supplied to the gas introduction pipe 20.

  In the lower part of the processing container 10, a plurality of exhaust ports 42 are provided in the container bottom surface 10 a. The reaction product gas generated in the processing vessel 10 and the surplus reaction gas or cleaning gas are discharged from the exhaust port 42 through the exhaust pipe 44 to the vacuum pump 46 side. As the vacuum pump 46, an oil-free dry pump is preferably used. This is because if ClF3 is used as the cleaning gas, the use of a wet pump may cause deterioration of the pump oil or deterioration of the pump itself due to chlorine or fluorine mixed in the oil.

  The discharge system downstream of the vacuum pump 46 is provided with a removal device 48 for removing harmful and dangerous gas components from the exhaust gas of the reaction gas or cleaning gas discharged from the pump. The removal device 48 accommodates a cylinder 50 containing a chemical for adsorbing or decomposing harmful and dangerous gas components.

  A quartz window 52 is attached to the bottom of the container below the susceptor 12, and a halogen lamp 54 for heating is disposed below the quartz window 52. During the film forming process, the light from the halogen lamp 54 passes through the quartz window 52 and irradiates the back surface of the susceptor 12, and the susceptor 12 is heated to, for example, 650 to 700 ° C. with the light energy. The semiconductor wafer 14 is heated to about 500 ° C. to 550 ° C., for example.

  Next, a film forming process of the tungsten film in this CVD apparatus and a cleaning process of this CVD apparatus will be described.

  First, the process for forming a tungsten film will be described. The semiconductor wafer 14 subjected to the film forming process is loaded onto the susceptor 12 through a gate valve 16 by a wafer transfer mechanism (not shown) such as a hand arm. Next, as reaction gases, for example, WF6 (tungsten hexafluoride) and Si H2 C12 (dichlorosilane) are introduced into the processing vessel 10 from the reaction gas supply system 22 through the gas introduction pipe 20 at a predetermined flow rate. The introduced reaction gas is sprayed onto the semiconductor wafer 14 through the perforated plate 18 to form a WSi (tungsten silicide) film on the surface of the semiconductor wafer 14. When WF6 and H2 are used as different reaction gases, a W (tungsten) film is formed on the surface of the semiconductor wafer 14.

  In this film forming process, the semiconductor wafer 14 is heated by the heating lamp 54 via the susceptor 12, but the processing container 10 itself is kept at a normal temperature (room temperature). The reaction gas decomposition products or most of the reaction products are deposited on the surface of the semiconductor wafer 14, but a part of the reaction gas adheres to the outer peripheral edge of the susceptor 12 and a wafer holding member (not shown). It adheres to the inner wall surface of 10 slightly. When the film forming process is completed, the semiconductor wafer 14 is unloaded from the susceptor 12 by the wafer transfer mechanism. During the unloading or loading, the film may be peeled off from the semiconductor wafer 14 or the susceptor 12, the wafer holding member, etc., and the peeled film piece adheres to the bottom surface 10 a of the processing container 10.

  When the film formation process as described above is performed a predetermined number of times, the film formation process is temporarily interrupted, the reaction gas supply system 22 and the heating lamp 54 are switched off, and the semiconductor wafer 14 is not contained in the processing vessel 10. In this state, the cleaning according to the present embodiment is performed at room temperature. Prior to this cleaning, purging with H2 gas or N2 gas or the like is performed, and the reaction gas is removed from the processing vessel 10.

  In the cleaning according to this embodiment, a cleaning gas obtained by diluting ClF3 gas with N2 gas to a predetermined concentration from the cleaning gas supply system 24 as described above is introduced into the processing vessel 10 through the gas introduction pipe 20, and the introduction thereof. The cleaned cleaning gas is supplied from the perforated plate 18 to the susceptor 12 and other parts of the apparatus.

  ClF3 gas is a chemically active gas and reacts well with films, particularly tungsten-based films, even without plasma. Therefore, the supply flow rate is controlled so that the cleaning gas is filled in the processing container 10, whereby ClF3 gas spreads to every corner in the processing container 10, and the WSi film or W film adhering to each part is ClF3. Etching is effectively performed only by receiving the supply of gas.

  Thus, the film on the bottom 10a of the container, which is difficult to remove by the conventional NF3 plasma cleaning method, can be easily removed by the cleaning method of this embodiment. Therefore, manual cleaning that bothers workers is unnecessary. When the ClF3 gas passes through the exhaust port 42 and the exhaust pipe 44, the film adhering thereto is also etched away.

  Further, since ClF3 gas has a good decomposability and is easily dissolved in an alkali solution or the like, the exhaust gas can be treated by the common removal device 48 in the same manner as the reaction gas exhaust gas. Therefore, a special removing device for cleaning is unnecessary.

  2-5 is a graph which shows the etching effect by the cleaning method of a present Example. The data shown in the figure shows that when a semiconductor wafer having a W film formed on the surface is placed on the susceptor 12 as a test material and the cleaning gas containing the ClF3 gas is supplied under various conditions, the W film of the semiconductor wafer is supplied. This was obtained in an experimental example in which the etching rate was measured.

  First, the graph of FIG. 2 shows the characteristics of the etching rate when the flow rate of ClF3 gas and N2 gas in the cleaning gas is kept constant at 500 sccm and the gas pressure is changed at room temperature. As shown in FIG. 2, as the gas pressure is increased, the reaction between the ClF3 gas and the W film is promoted to increase the etching rate, and the etching rate is about 2000 to 4000 angstrom / min with respect to the pressure of 10 to 50 Toor. It can be seen that the rate is obtained.

  The graph of FIG. 3 shows the characteristics of the etching rate when the flow rate of N2 gas is kept constant at 1500 sccm, the pressure is kept constant at 10 Torr, and the flow rate of ClF3 gas is changed at room temperature. As shown in FIG. 3, as the flow rate of ClF3 gas is increased, the supply amount of ClF3 gas is increased and the etching rate is increased, and an etching rate of about 3000 to 6000 angstroms / min is obtained with respect to a ClF3 gas flow rate of 400 to 1000 sccm. I understand.

  The graph of FIG. 4 shows the characteristics of the etching rate when the flow rate of ClF3 gas is kept constant at 500 sccm, the pressure is kept constant at 10 Torr, and the flow rate of N2 gas is changed at room temperature. From FIG. 4, it can be seen that as the N2 gas flow rate is increased, the ClF3 gas is diluted to lower the etching rate, and an etching rate of about 4500 to 2500 angstroms / min is obtained with respect to the N2 gas flow rate of 500 to 5000 sccm. .

  The graph of FIG. 5 shows the characteristics of the etching rate when the total flow rate is changed with the pressure maintained at 10 Torr and the flow rate ratio of ClF3 gas and N2 gas constant (1: 3) at room temperature. From this figure, as the flow rate of the cleaning gas is increased, the supply amount of ClF3 gas is increased and the etching rate is increased, and about 3600 to 4800 angstroms / min with respect to the flow rate of ClF3 / N2 gas of 400/1200 to 1000/3000. It can be seen that the etching rate can be obtained.

  As described above, according to the cleaning method using ClF3 gas, an etching rate of 3000 angstroms / min or more can be easily obtained by appropriately selecting conditions such as gas flow rate, pressure, and ClF3 gas concentration even at room temperature. Can do. It has been confirmed by experiments that the same etching rate can be obtained with the WSi film. In this respect, since the etching rate obtained by the conventional plasma type cleaning method using NF3 gas is at most about 2000 angstrom / min, the cleaning efficiency is not inferior to the conventional method.

  Next, an embodiment of the present invention will be described. In one embodiment of the present invention, in a cold wall type processing apparatus, for example, a processing apparatus as shown in FIG. 1, a heatable portion such as a susceptor 14, a wafer holding member (not shown), an inner wall of the processing container 10, etc. A cleaning gas containing ClF3 is supplied to ClF3 while maintaining a high temperature within the range of the corrosion resistance temperature to clean each part of the container 10 and the like, in particular, a heatable part.

  FIG. 6 shows preferred materials that can be used for the heatable part in the cold wall type processing apparatus of the present invention, that is, SUS430, SUS304, SUS316, aluminum (Al), nickel (Ni), inconel, quartz, alumina (Al2). The respective corrosion resistance temperatures of silicon carbide (SiC), zirconium oxide (ZrO2) and aluminum nitride (AlN) with respect to ClF3 are shown. When these materials are used for heatable parts such as susceptors, wafer holding members, processing containers, etc., the cleaning speed increases as the temperature increases. However, if the corrosion resistance range is exceeded, particles are generated from the member itself, which is not good. Therefore, it is desirable to keep it below the corrosion resistance temperature of each part even if it is high temperature.

  FIG. 7 shows that the heatable part in the cold wall type processing apparatus is made of silicon carbide (SiC), the degree of vacuum in the container (10 Torr), the flow rate of the cleaning gas (ClF3 / N2) (100/2000 sccm), and the cleaning gas. The characteristics of the etching rate when changing the cleaning temperature while fixing various conditions of the supply method (simultaneous delivery of ClF3 / N2) and the cleaning time (20 seconds) are shown. As can be seen from FIG. 7, the etching rate increases as the cleaning temperature is increased, and an etching rate of about 3200 angstroms / min is obtained at a high temperature around 200 ° C.

  As the heating means, a heating means for heat treatment such as the halogen lamp 54 in FIG. 1 may be used. Further, a heating means such as nichrome wire is provided inside the wall of the processing vessel 10 for cleaning. It may be buried.

  In the above-described embodiment, cleaning is performed by removing the W film or WSi film. However, the cleaning method of the present invention is not limited to a tungsten-based film but also for an undesired film of other film forming materials. Can be used. Further, although the cold wall type processing apparatus in the above-described embodiment is a single-wafer type CVD apparatus, the cleaning method of the present invention is not limited to such a film forming processing apparatus, and other devices such as a sputtering apparatus can be used. It can also be used for a cold wall forming film processing apparatus.

1 is a schematic cross-sectional view showing an overall configuration of a cold wall type single wafer CVD apparatus for carrying out a cleaning method according to an embodiment of the present invention. It is a graph which shows the characteristic of the etching rate with respect to the pressure in the cleaning method of an embodiment. It is a graph which shows the characteristic of the etching rate with respect to the flow volume of ClF3 gas in the cleaning method of embodiment. It is a graph which shows the characteristic of the etching rate with respect to the flow volume of N2 gas in the cleaning method of embodiment. It is a graph which shows the characteristic of the etching rate with respect to the total flow volume of the cleaning gas in the cleaning method of embodiment. It is a table | surface which shows each corrosion-resistant temperature with respect to ClF3 of the various materials which can be utilized for the heatable part in the cold wall formation film processing apparatus in embodiment. It is a graph which shows the characteristic of the etching rate with respect to the temperature in the cleaning method of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processing container 12 Susceptor 14 Semiconductor wafer 22 Reaction gas supply system 24 Cleaning gas supply system 30 ClF3 gas supply part 32 N2 gas supply part 48 Removal apparatus

Claims (11)

A processing container capable of being vacuumed;
A substrate mounting table for mounting a substrate to be processed in the processing container;
An installation table heating means for heating the substrate installation table;
A processing gas supply means for supplying a processing gas for film formation into the processing container through a perforated plate facing the substrate mounting table in the film forming processing step;
Cleaning gas supply means for supplying ClF3 gas to the processing container through the perforated plate in the cleaning process, and the substrate mounting table is heated within the range of the corrosion resistance temperature by the setting table heating means in the cleaning process. In this state, the cleaning gas supply means supplies the ClF3 gas into the processing container to remove the film adhering to the substrate mounting table.   2. The film forming apparatus according to claim 1, further comprising a wall heating unit that heats the wall of the processing container, wherein the wall heating unit heats the wall within a range of a corrosion resistance temperature in the cleaning step.   The film forming apparatus according to claim 2, wherein the wall heating unit is configured by embedding a heat generating unit in the wall.   4. The film forming apparatus according to claim 2, wherein the wall is made of aluminum.   The film forming apparatus according to claim 1, wherein a material of the substrate mounting table includes aluminum nitride.   2. The film forming apparatus according to claim 1, wherein the material of the substrate mounting table includes quartz.   The film forming apparatus according to claim 1, wherein a material of the substrate mounting table includes silicon carbide.   The film forming apparatus according to claim 1, wherein a material of the substrate mounting table includes alumina.   A gas introduction pipe for introducing the processing gas and the cleaning gas is connected to the processing container, and a processing gas supply system for supplying the processing gas and a cleaning gas supply system for supplying the cleaning gas are connected to the gas introduction pipe. The film forming apparatus according to claim 1.   10. The process according to claim 9, wherein the supply of the processing gas to the processing container and the supply of the cleaning gas are switched by open / close valves provided in the processing gas supply system and the cleaning gas supply system. Membrane processing equipment.   A processing container capable of being evacuated, a substrate mounting table for mounting a substrate to be processed in the processing container, a mounting table heating means for heating the substrate mounting table, and a processing gas for film formation in a film forming process step In a film forming apparatus having a processing gas supply means for supplying the processing container into the processing container through a perforated plate facing the substrate mounting base, the substrate mounting base is heated within the range of the corrosion resistance temperature by the mounting base heating means. In this state, a cleaning method is characterized in that a cleaning gas supply means supplies ClF3 gas into the processing container through the perforated plate to remove the film adhering to the substrate mounting table.

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