Cleaning method and film deposition apparatus executing the cleaning method for uniformly cleaning rotary table

A method performed by a film deposition apparatus including a process chamber and a rotary table that is disposed in the process chamber and includes a substrate-mounting surface on which a substrate is placeable. The method includes a first cleaning process of supplying a cleaning gas from above the substrate-mounting surface of the rotary table while rotating the rotary table in a first cleaning position, and a second cleaning process of supplying the cleaning gas from above the substrate-mounting surface of the rotary table while rotating the rotary table in a second cleaning position that is lower than the first cleaning position.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based upon and claims the benefit of priority of Japanese Patent Application No. 2016-237074, filed on Dec. 6, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of this disclosure relates to a cleaning method and a film deposition apparatus.

2. Description of the Related Art

In a film deposition apparatus used for manufacturing semiconductor devices, a film is deposited not only on the upper surface of a substrate but also on the upper surface, the side surface, and the lower surface of a rotary table on which the substrate is placed. When the film deposited on the upper surface, the side surface, and the lower surface of the rotary table becomes thick, the film flakes off and forms particles. For this reason, a cleaning gas is routinely supplied into a process chamber to remove the film deposited on the upper surface, the side surface, and the lower surface of the rotary table (see, for example, Japanese Laid-Open Patent Publication No. 2010-153805).

With the related-art method, however, because the gap between a nozzle for supplying the cleaning gas and the rotary table is narrow, the flow rate of the cleaning gas supplied from the nozzle becomes high and most of the cleaning gas is ejected before the film deposited on the upper surface of the rotary table is removed. This in turn increases the cleaning time necessary to remove the film deposited on the upper surface of the rotary table, and causes the time necessary to remove the film to vary depending on surfaces of the rotary table.

SUMMARY OF THE INVENTION

In an aspect of this disclosure, there is provided a method performed by a film deposition apparatus including a process chamber and a rotary table that is disposed in the process chamber and includes a substrate-mounting surface on which a substrate is placeable. The method includes a first cleaning process of supplying a cleaning gas from above the substrate-mounting surface of the rotary table while rotating the rotary table in a first cleaning position, and a second cleaning process of supplying the cleaning gas from above the substrate-mounting surface of the rotary table while rotating the rotary table in a second cleaning position that is lower than the first cleaning position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described below with reference to the accompanying drawings. Throughout the specification and the drawings, the same reference number is assigned to substantially the same components, and repeated descriptions of those components are omitted.

An example of a film deposition apparatus that can perform cleaning methods according to embodiments of the present invention is described.FIG. 1is a cross-sectional view of a film deposition apparatus according to an embodiment.FIG. 2is a perspective view of an internal configuration of a vacuum chamber of the film deposition apparatus ofFIG. 1.FIG. 3is a plan view of the internal configuration of the vacuum chamber of the film deposition apparatus ofFIG. 1. InFIGS. 2 and 3, a top plate11is omitted for illustration purposes.

As illustrated byFIGS. 1 through 3, the film deposition apparatus may include a vacuum chamber1having a substantially circular planar shape, and a rotary table2that is disposed in the vacuum chamber1such that the center of the vacuum chamber1matches the center of rotation of the rotary table2. The vacuum chamber1is a process chamber where a film deposition process is performed on the upper surface of a semiconductor wafer (which is hereafter referred to as a “wafer W”) that is a substrate. The vacuum chamber1may include a chamber body12shaped like a closed-end cylinder and a top plate11that is hermetically and detachably attached via a sealing part13such as an O-ring to the upper surface of the chamber body12.

The rotary table2is rotatably disposed in the vacuum chamber1. The rotary table2may be formed of, for example, quartz. A central portion of the rotary table2is fixed to a core21having a cylindrical shape. The core21is fixed to an upper end of a rotational shaft22that extends in the vertical direction. The rotational shaft22passes through a bottom14of the vacuum chamber1, and a lower end of the rotational shaft22is attached to a drive unit23. The drive unit23includes, for example, a pneumatic cylinder and a stepping motor. The drive unit23moves the rotational shaft22up and down and thereby moves the rotary table up and down. Also, the drive unit23rotates the rotational shaft22about a vertical axis and thereby rotates the rotary table2. The rotational shaft22and the drive unit23are housed in a tubular case20with an opening at the upper end. A flange formed at the upper end of the case20is hermetically attached to a lower surface of the bottom14of the vacuum chamber1via a bellows16that is expandable and contractible in the vertical direction such that the internal atmosphere of the case20is isolated from the external atmosphere. Because the bellows16expands and contracts as the rotary table2moves up and down, the internal atmosphere of the case20can be kept isolated from the external atmosphere.

As illustrated inFIGS. 2 and 3, multiple (six in this example) circular recesses2afor holding wafers W are formed in the upper surface of the rotary table2. The recesses2aare arranged along the rotational direction (or the circumferential direction) of the rotary table2. InFIG. 3, for brevity, the wafer W is illustrated only in one of the recesses2a. Each recess2ahas an inside diameter that is slightly (e.g., by 4 mm) greater than the diameter of the wafer W, and has a depth that is substantially the same as the thickness of the wafer W. Accordingly, when the wafer W is placed in the recess2a, the height of the upper surface of the wafer W becomes substantially the same as the height of the upper surface (in an area where no recess2ais formed) of the rotary table2. Through holes (not shown) are formed in the bottom of each recess2a. For example, three elevating pins (not shown) pass through the through holes to support the lower surface of the wafer W and move the wafer W up and down.

As illustrated inFIGS. 2 and 3, reaction gas nozzles31and32, a cleaning gas nozzle33, and separation gas nozzles41and42, which are formed of, for example, quartz, are provided above the rotary table and arranged at intervals along the circumferential direction of the vacuum chamber1. In this example, the separation gas nozzle41, the cleaning gas nozzle33, the reaction gas nozzle31, the separation gas nozzle42, and the reaction gas nozzle32are arranged clockwise (along the rotational direction of the rotary table2) in this order from a transfer port15. The nozzles31,32,33,41, and42are inserted through an outer wall of the chamber body12into the vacuum chamber1such that the nozzles31,32,33,41, and42, extend in the radial direction of the chamber body12in parallel with the upper surface of the rotary table2. Gas introduction ports31a,32a,33a,41a, and42a(seeFIG. 3) at the ends of the nozzles31,32,33,41, and42are fixed to the outer wall of the chamber body12.

In the present embodiment, as illustrated inFIG. 3, the reaction gas nozzle31is connected via a pipe110and a flow rate controller120to a first reaction gas supply source130for supplying a first reaction gas. The reaction gas nozzle32is connected via a pipe111and a flow rate controller121to a second reaction gas supply source131for supplying a second reaction gas. The cleaning gas nozzle33is connected via a pipe112and a flow rate controller122to a cleaning gas supply source132for supplying a cleaning gas. The separation gas nozzles41and42are connected via pipes and flow rate control valves (not shown) to separation gas supply sources (not shown) for supplying a separation gas. Examples of separation gases include noble gases such as a helium (He) gas and an argon (Ar) gas and inactive gases such as a nitrogen (N2) gas. In the present embodiment, an N2gas is used as an example of the separation gas.

Each of the reaction gas nozzles31and32includes multiple gas discharge holes35(seeFIG. 4) that are open toward the rotary table2and arranged at an interval of, for example, 10 mm along the longitudinal direction of the respective reaction gas nozzles31and32. A region below the reaction gas nozzle31is a first process region P1where the first reaction gas is adsorbed onto the wafer W. A region below the reaction gas nozzle32is a second process region P2where the second reaction gas, which reacts with the first reaction gas adsorbed onto the wafer W in the first process region P1, is supplied to form a molecular layer of a reaction product. The molecular layer of the reaction product constitutes a film to be deposited (or formed).

The first reaction gas may be any type of gas. Generally, a material gas of a film to be formed is selected as the first reaction gas. For example, when a silicon dioxide film is to be formed, a silicon-containing gas such as a Bis(tertiary-butylamino)silane (BTBAS) gas is selected as the first reaction gas.

The second reaction gas may be any type of reaction gas that can react with the first reaction gas to form a reaction product. For example, when a silicon dioxide film is to be formed, an oxide gas such as an ozone (O3) gas is selected as the second reaction gas.

The cleaning gas nozzle33is used when a cleaning process is performed. Similarly to the reaction gas nozzles31and32, the cleaning gas nozzle33includes multiple gas discharge holes (not shown) that are open toward the rotary table2and arranged at an interval of, for example, 10 mm along the longitudinal direction of the cleaning gas nozzle33. In this example, the cleaning gas nozzle33supplies a cleaning gas to the first process region P1. Also, the cleaning gas nozzle33may be provided in a position where the cleaning gas nozzle33can supply the cleaning gas to the second process region P2. Further, the cleaning gas nozzle33may be provided both in a position where the cleaning gas nozzle33can supply the cleaning gas to the first process region P1and a position where the cleaning gas nozzle33can supply the cleaning gas to the second process region P2. The cleaning gas may be any type of gas. For example, when used to remove a silicon dioxide film, a fluorine-containing gas such as chlorine fluoride (ClF3) or nitrogen trifluoride (NF3) is selected as the cleaning gas. Also, a combination of these gases may be used.

As illustrated inFIGS. 2 and 3, two protruding parts4are provided in the vacuum chamber1. The protruding parts4form separation regions D together with the separation gas nozzles41and42. The protruding parts4are attached to the lower surface of the top plate11to protrude toward the rotary table2. Each protruding part4has a fan-like planar shape whose apex is cut off to form an arc. The protruding part4is disposed such that its inner arc is connected to a protrusion5(described later), and its outer arc extends along the inner circumferential surface of the chamber body12of the vacuum chamber1.

FIG. 4is a cross-sectional view of a part of the vacuum chamber1from the reaction gas nozzle31to the reaction gas nozzle32, which is taken along a concentric circle of the rotary table2of the film deposition apparatus ofFIG. 1. InFIG. 4, for illustration purposes, the wafer W is omitted.

As illustrated inFIG. 4, the protruding part4is attached to the lower surface of the top plate11. Accordingly, in the vacuum chamber1, a flat and lower ceiling surface (first ceiling surface)44is formed by the lower surface of the protruding part4, and a higher ceiling surface (second ceiling surface)45is formed by the lower surface of the top plate11. The second ceiling surface45is located on both sides of the first ceiling surface44in the circumferential direction, and is at a higher position than the first ceiling surface44. The first ceiling surface44has a fan-like planar shape whose apex is cut off to form an arc. Also, as illustrated inFIG. 4, a groove43extending in the radial direction is formed in the middle of the protruding part4in the circumferential direction. The separation gas nozzle42is placed in the groove43. A groove43is also formed in the other protruding part4, and the separation gas nozzle41is placed in the groove43. The reaction gas nozzles31and32are provided in spaces below the second ceiling surface45. The reaction gas nozzles31and32are positioned apart from the second ceiling surface45and close to the wafer W. As illustrated inFIG. 4, the reaction gas nozzle31is provided in a space481that is below the second ceiling surface45and on the right side of the protruding part4, and the reaction gas nozzle32is provided in a space482that is below the second ceiling surface45and on the left side of the protruding part4.

Each of the separation gas nozzles41and42placed in the groove43of the protruding part4includes multiple gas discharge holes42h(seeFIG. 4) that are open toward the rotary table2and arranged at an interval of, for example, 10 mm along the longitudinal direction of the respective separation gas nozzles41and42.

A narrow separation space H is formed between the first ceiling surface44and the upper surface of the rotary table2. When an N2gas is supplied from the gas discharge holes42hof the separation gas nozzle42, the N2gas flows through the separation space H into the spaces481and482. Because the volume of the separation space H is less than the volumes of the spaces481and482, the pressure in the separation space H can be made higher than the pressures in the spaces481and482by supplying the N2gas. Thus, the separation space H with a high pressure is formed between the spaces481and482. Also, the flow of the N2gas from the separation space H into the spaces481and482functions as a counter flow to the first reaction gas from the first process region P1and the second reaction gas from the second process region P2. Accordingly, the separation space H separates the first reaction gas from the first process region P1and the second reaction gas from the second process region P2. This configuration prevents the first reaction gas from mixing and reacting with the second reaction gas in the vacuum chamber1.

A height h1of the first ceiling surface44from the upper surface of the rotary table2is preferably determined based on the pressure in the vacuum chamber1, the rotational speed of the rotary table2, and/or the amount of supplied separation gas during a film forming process so that the pressure in the separation space H becomes higher than the pressures in the spaces481and482.

A protrusion5(seeFIGS. 2 and 3) is formed on the lower surface of the top plate11to surround the core21to which the rotary table2is fixed. In the present embodiment, the protrusion5is connected to the center-side ends of the protruding parts4. The lower surface of the protrusion5is at the same height as the first ceiling surface44.

FIG. 1is a cross-sectional view of the film deposition apparatus taken along line I-I′ ofFIG. 3and illustrates a section including the second ceiling surface45. In contrast,FIG. 5is a cross-sectional view of another section of the film deposition apparatus including the first ceiling surface44. As illustrated inFIG. 5, an L-shaped bent part46is formed at the periphery of each protruding part4(i.e., an end of the protruding part4that is closer to the outer wall of the vacuum chamber1). The bent part46faces the outer end face of the rotary table2. Similarly to the protruding part4, the bent part46prevents the first and second reaction gases from entering the separation region D and thereby prevents the first and second reaction gases from being mixed with each other. The protruding part4is provided on the top plate11, and the top plate11is detachable from the chamber body12. Therefore, a small gap is provided between the outer surface of the bent part46and the chamber body12. The gap between the inner surface of the bent part46and the outer end face of the rotary table2and the gap between the outer surface of the bent part46and the chamber body12may be set at a value that is substantially the same as the height of the first ceiling surface44from the upper surface of the rotary table2.

As illustrated inFIG. 5, in the separation region D, the inner surface of the chamber body12is a vertical surface disposed close to the outer surface of the bent part46. In contrast, as illustrated inFIG. 1, in regions other than the separation region D, a portion of the inner surface of the chamber body12, which extends from a position facing the outer end face of the rotary table2to the bottom14, is recessed outward. The recessed portion has a substantially-rectangular cross-sectional shape, and is referred to as an evacuation region in the descriptions below. More specifically, an evacuation region communicating with the first process region P1is referred to as a first evacuation region E1, and an evacuation region communicating with the second process region P2is referred to as a second evacuation region E2. As illustrated inFIGS. 1 through 3, a first evacuation port61is formed in the bottom of the first evacuation region E1, and a second evacuation port62is formed in the bottom of the second evacuation region E2. As illustrated inFIG. 1, each of the first evacuation port61and the second evacuation port62is connected via an evacuation pipe63to a vacuum pump64that is a vacuum evacuator. Also, a pressure controller65is provided between the vacuum pump64and the evacuation pipe63.

As illustrated inFIGS. 1 and 5, a heater unit7is provided in a space between the rotary table2and the bottom14of the vacuum chamber1. The heater unit7heats, via the rotary table2, the wafer W on the rotary table2to a temperature defined by a process recipe. A ring-shaped cover71(seeFIG. 5) is provided below and near the outer edge of the rotary table2. The cover71separates an atmosphere in a space above the rotary table2and in the first and second evacuation regions E1and E2from an atmosphere in a space where the heater unit7is provided, and thereby prevents gases from entering a region below the rotary table2. The cover71includes an inner part71aand an outer part71b. The inner part71ais provided below the rotary table2and faces the outer edge of the rotary table2and a space surrounding the outer edge of the rotary table2. The outer part71bis provided between the inner part71aand the inner surface of the vacuum chamber1. The outer part71bis disposed below the bent part46formed at the outer end of the protruding part4in the separation region D. The upper end of the outer part71bis positioned close to the lower end of the bent part46. The inner part71ais disposed below the outer edge of the rotary table2(and below a space surrounding the outer edge of the rotary table2) and surrounds the entire circumference of the heater unit7.

A portion of the bottom14, which is closer to the center of rotation than the space housing the heater unit7, protrudes upward toward the core21and the central portion of the lower surface of the rotary table2, and forms a protrusion12a. A narrow space is formed between the protrusion12aand the core21. Also, a narrow space is formed between the rotational shaft22and the inner surface of a through hole formed in the bottom14for the rotational shaft22. These narrow spaces communicate with the case20. A purge gas supply pipe72is connected to the case20. The purge gas supply pipe72supplies an N2gas as a purge gas to purge the narrow spaces. Also, purge gas supply pipes73are connected to the bottom14of the vacuum chamber1at positions below the heater unit7(only one purge gas supply pipe73is illustrated inFIG. 5). The purge gas supply pipes73are arranged in the circumferential direction at predetermined angular intervals and used to purge the space housing the heater unit7. A lid7ais provided between the heater unit7and the rotary table2to prevent entry of gases into the space housing the heater unit7. The lid7acovers an area along the circumferential direction and between the inner surface of the outer part71b(or the upper surface of the inner part71a) and the upper end of the protrusion12a. The lid7amay be formed of, for example, quartz.

A separation gas supply pipe51is connected to a central portion of the top plate11of the vacuum chamber1, and supplies an N2gas as a separation gas into a space52between the top plate11and the core21. The separation gas supplied into the space52flows through a narrow space50between the protrusion5and the rotary table2, and flows toward the periphery of the rotary table2along the upper surface of the rotary table2on which the wafer W is placed. Due to the separation gas, the pressure in the space50is kept higher than the pressures in the space481and the space482. Accordingly, the space50prevents the first reaction gas (e.g., a BTBAS gas) supplied into the first process region P1and the second reaction gas (e.g., an O3gas) supplied into the second process region P2from passing through a central region C and mixing with each other. That is, the space50(or the central region C) functions in a manner similar to the separation space H (or the separation region D).

As illustrated inFIGS. 2 and 3, a transfer port15is formed in the side wall of the vacuum chamber1. The transfer port15is used to transfer the wafer W between an external conveying arm10(seeFIG. 3) and the rotary table2. The transfer port15is opened and closed by a gate valve (not shown). The wafer W is transferred between the recess2aof the rotary table2and the conveying arm10when the recess2ais at a position (transfer position) facing the transfer port15. Elevating pins and an elevating mechanism (not shown) for lifting the wafer W are provided at the transfer position below the rotary table2. The elevating pins pass through the recess2aand push the lower surface of the wafer W upward.

As illustrated inFIG. 1, the film deposition apparatus of the present embodiment also includes a controller100implemented by a computer for controlling operations of the entire film deposition apparatus. A memory of the controller100stores a program according to which the controller100controls the film deposition apparatus to perform a cleaning method described later. The program includes steps corresponding to the cleaning method. The program is stored in a medium102such as a hard disk, a compact disk, a magneto-optical disk, a memory card, or a flexible disk, is read by a reading device into a storage101, and installed in the controller100.

A film deposition method (or a film deposition process) according to an embodiment is described below. In the descriptions below, it is assumed that a silicon dioxide film is formed.

First, the rotary table2is rotated such that the recess2ais positioned to face the transfer port15(seeFIGS. 2 and 3), and then the gate valve (not shown) is opened. Next, the wafer W is carried by the conveying arm10through the transfer port15into the vacuum chamber1. The wafer W is received by the elevating pins (not shown). After the conveying arm10is pulled out of the vacuum chamber1, the elevating pins are lowered by the elevating mechanism (not shown), and the wafer W is placed in the recess2a. The above “carry-in” process is repeated six times to place six wafers W in the corresponding recesses2a.

Next, an N2gas is supplied from the separation gas nozzles41and42, the separation gas supply pipe51, and the purge gas supply pipes72and73, and the inside of the vacuum chamber1is maintained at a predetermined pressure by the vacuum pump64and the pressure controller65(seeFIG. 1). Also, the rotary table2is rotated, for example, clockwise (in a direction indicated by an arrow A inFIG. 3) at a predetermined speed. The rotary table2is heated in advance by the heater unit7to a predetermined temperature and as a result, the wafers W on the rotary table2are heated. After the wafers W are heated and maintained at a predetermined temperature, a BTBAS gas is supplied by the reaction gas nozzle31to the first process region P1, and an O3gas is supplied by the reaction gas nozzle32to the second process region P2.

When each wafer W passes through the first process region P1below the reaction gas nozzle31, BTBAS molecules are adsorbed on the surface of the wafer W. Also, when the wafer W passes through the second process region P2below the reaction gas nozzle32, O3molecules are adsorbed on the surface of the wafer W, and the BTBAS molecules are oxidized by O3. Accordingly, when the wafer W passes through the first process region P1and the second process region P2once as the rotary table2rotates, one molecular layer (or two or more molecular layers) of silicon dioxide is formed on the surface of the wafer W. The wafer W alternately passes through the first process region P1and the second process region P2multiple times until a silicon dioxide film with a predetermined thickness is deposited on the surface of the wafer W. After the silicon dioxide film with the predetermined thickness is deposited on the wafer W, supply of the BTBAS gas and the O3gas is stopped, and the rotation of the rotary table2is stopped. Then, through a reverse process of the carry-in process, the wafers W are carried out of the vacuum chamber1by the conveying arm10, and the film deposition process ends.

Thus, the above film deposition process can form a silicon dioxide film that is a reaction product of the BTBAS gas and the O3gas on the surface of the wafer W.

In the film deposition process, not only the surface of the wafer W but also the upper surface, the side surface, and the lower surface of the rotary table are exposed to the gases. Accordingly, a reaction product such as a silicon dioxide film is formed not only on the surface of the wafer W but also on the upper surface, the side surface, and the lower surface of the rotary table2. When the film of a reaction product such as a silicon dioxide film formed on the upper surface, the side surface, and the lower surface of the rotary table2becomes thick, the film flakes off and forms particles. If such particles are generated in the vacuum chamber1, the particles are introduced into a silicon dioxide film formed on the surface of the wafer W, and the quality of the silicon dioxide film is reduced.

For this reason, a cleaning process is generally performed, for example, when a film of a reaction product formed on the upper surface of the rotary table2reaches a predetermined thickness, when the amount of particles in a silicon dioxide film formed on the wafer W exceeds a predetermined value, or when the continuous operation time exceeds a predetermined value.

With this method, however, when the gap between a nozzle for supplying a cleaning gas and a rotary table is narrow, the flow rate of the cleaning gas supplied from the nozzle becomes high and most of the cleaning gas is ejected before a film deposited on the upper surface of the rotary table is removed. This in turn increases a cleaning time necessary to remove the film deposited on the upper surface of the rotary table, and causes the time necessary to remove the film to vary depending on surfaces of the rotary table.

Below, a cleaning method according to an embodiment is described. The cleaning method of the embodiment can reduce the cleaning time and can uniformly clean the rotary table2.

A cleaning method according to an embodiment is described below. The cleaning method of the present embodiment includes two cleaning processes (a first cleaning process and a second cleaning process) that are performed while changing the position of the rotary table2in the vertical direction. In the first cleaning process, a cleaning gas is supplied from above a substrate-mounting surface of the rotary table2while rotating the rotary table2in a first cleaning position in the vacuum chamber1. In the second cleaning process, a cleaning gas is supplied from above the substrate-mounting surface of the rotary table2while rotating the rotary table2in a second cleaning position lower than the first cleaning position. Either the same cleaning gas or different cleaning gases may be used in the first cleaning process and the second cleaning process.

In the descriptions below, it is assumed that a process of forming a silicon dioxide film has been performed according to the film deposition method described above, and a reaction product such as a silicon dioxide film deposited on the upper surface, the side surface, and the lower surface of the rotary table2during the film forming process is to be removed.FIG. 6is a timing chart illustrating an exemplary cleaning method according to the present embodiment.FIGS. 7 and 8are cross-sectional views of the film deposition apparatus ofFIG. 1and used to describe operations to move the rotary table2up and down.FIG. 7illustrates a state where the rotary table2is in an up position, andFIG. 8illustrates a state where the rotary table2is in a down position.

As illustrated inFIG. 6, the cleaning method of the present embodiment includes a first purge process, a first cleaning process, a second cleaning process, and a second purge process that are performed in this order. The first purge process and the second purge process may be omitted.

In the first purge process, while no wafer W is in the recesses2aof the rotary table2, the rotary table2is moved by the drive unit23to an up position, and an N2gas is supplied from the separation gas nozzles41and42, the separation gas supply pipe51, and the purge gas supply pipes72and73. During the first purge process, the inside of the vacuum chamber1is maintained at a predetermined pressure by the vacuum pump64and the pressure controller65. As a result, an N2gas atmosphere is formed in the vacuum chamber1.

Next, in the first cleaning process, as illustrated byFIG. 7, the rotary table2is kept in the up position and rotated at a predetermined speed, and a ClF3gas is supplied from the cleaning gas nozzle33to the first process region P1. After a first time period T1passes, the supply of the ClF3gas is stopped. The first time period T1may be determined based on the thickness of a reaction product deposited on the upper surface, the side surface, and the lower surface of the rotary table2.

Next, in the second cleaning process, as illustrated byFIG. 8, the rotary table2is moved to the down position by the drive unit23and rotated at a predetermined speed in the down position, and the ClF3gas is supplied from the cleaning gas nozzle33to the first process region P1. The down position is located lower than the up position. After a second time period T2passes, the supply of the ClF3gas is stopped. The second time period T2may be determined based on the thickness of a reaction product deposited on the upper surface, the side surface, and the lower surface of the rotary table2.

Next, in the second purge process, while the rotary table2is kept in the down position, the N2gas is supplied from the separation gas nozzles41and42, the separation gas supply pipe51, and the purge gas supply pipes72and73. During the second purge process, the inside of the vacuum chamber1is maintained at a predetermined pressure by the vacuum pump64and the pressure controller65. After a predetermined period of time, the supply of the N2gas from the separation gas nozzles41and42, the separation gas supply pipe51, and the purge gas supply pipes72and73is stopped, and the entire cleaning process ends.

In the cleaning method of the present embodiment, the cleaning gas is supplied into the vacuum chamber1while the rotary table2is kept at two different positions (the up position and the down position) in the vertical direction to clean the upper surface, the side surface, and the lower surface of the rotary table2. In the up position, because the gap between the upper surface of the rotary table2and the cleaning gas nozzle33is narrow, the flow rate of the ClF3gas supplied from the cleaning gas nozzle33becomes high, and a time for which the ClF3gas remains on the upper surface of the rotary table2becomes short. This makes possible to increase the rate of etching of a reaction product such as a silicon dioxide film deposited on the side surface and the lower surface of the rotary table2. In the down position, because the gap between the upper surface of the rotary table2and the cleaning gas nozzle33is wide, the flow rate of the ClF3gas supplied from the cleaning gas nozzle33becomes low, and a time for which the ClF3gas remains on the upper surface of the rotary table2becomes long. This makes possible to increase the rate of etching of a reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2. Thus, with the above cleaning method, it is possible to efficiently remove a reaction product such as a silicon dioxide film deposited on the side surface and the lower surface of the rotary table2while the rotary table2is kept in the up position, and to efficiently remove a reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2while the rotary table2is kept in the down position. This in turn makes it possible to reduce the cleaning time and to uniformly clean the rotary table2.

The ratio between the first time period T1and the second time period T2is preferably determined based on the amount of the reaction product such as a silicon dioxide film deposited on the side surface and/or the lower surface of the rotary table2and the amount of the reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2. More specifically, when the amount of the reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2is greater than the amount of the reaction product such as a silicon dioxide film deposited on the side surface and/or the lower surface of the rotary table2, the second time period T2is preferably made longer than the first time period T1. In contrast, when the amount of the reaction product such as a silicon dioxide film deposited on the side surface and/or the lower surface of the rotary table2is greater than the amount of the reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2, the first time period T1is preferably made longer than the second time period T2.

The flow rate of the N2gas supplied from the separation gas supply pipe51in the second cleaning process is preferably made lower than that in the first cleaning process. This decreases the flow rate of the cleaning gas that flows from the central region C of the rotary table2toward the first evacuation region E1and the second evacuation region E2. This in turn increases the time for which the cleaning gas remains on the upper surface of the rotary table2, and thereby makes it possible to efficiently remove the reaction product such as a silicon dioxide film deposited on the upper surface of the rotary table2.

In the cleaning method of the above embodiment, the first cleaning process is performed while the rotary table2is in the up position, and the second cleaning process is performed while the rotary table2is in the down position. However, the present invention is not limited to this embodiment.

FIGS. 9A through 9Eare timing charts illustrating other examples of cleaning methods according to embodiments of the present invention.

For example, as illustrated byFIG. 9A, the first cleaning process may be performed after the second cleaning process. Here, in the first cleaning process, cleaning is performed while the rotary table2is kept in the up position. In the second cleaning process, cleaning is performed while the rotary table2is kept in the down position.

Also, as illustrated byFIG. 9B, a third cleaning process may be performed after the first cleaning process and before the second cleaning process. Here, in the third cleaning process, cleaning is performed while moving the rotary table2downward from the up position to the down position.

Also, as illustrated byFIG. 9C, a fourth cleaning process may be performed after the second cleaning process and before the first cleaning process. Here, in the fourth cleaning process, cleaning is performed while moving the rotary table2upward from the down position to the up position.

Also, as illustrated byFIG. 9D, the first cleaning process and the second cleaning process may be alternately repeated.

Further, as illustrated byFIG. 9E, the first cleaning process, the third cleaning process, the second cleaning process, and the fourth cleaning process may be repeated in this order.

Cleaning methods and a film deposition apparatus according to the embodiments of the present invention are described above. However, the present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.

In the above embodiments, it is assumed that a silicon dioxide film is formed. However, the cleaning methods according to the embodiments of the present invention may also be applied to cases where other types of films are formed.

The above embodiments are described using a semi-batch-type film deposition apparatus that performs a film deposition process on multiple wafers W placed on the rotary table2at once. However, the present invention may also be applied to other types of film deposition apparatuses. For example, the present invention may also be applied to a batch-type film deposition apparatus that performs a film deposition process on each batch of many wafers W placed in a wafer boat at once, and to a single-wafer film deposition apparatus that performs a film deposition process on one wafer W each time.

An aspect of this disclosure provides a cleaning method and a film deposition apparatus that can reduce the cleaning time and can uniformly clean a rotary table.