Film-forming apparatus and film-forming method

An apparatus for forming a thin film by repeating, plural times, a cycle including supplying and adsorbing a precursor gas onto a substrate and generating a reaction product by allowing the precursor gas on the substrate to react with a reaction gas, which includes: a main precursor gas supply part for supplying the precursor gas; a reaction gas supply part for supplying the reaction gas; an adjustment-purpose precursor gas supply part for supplying an adjustment-purpose precursor gas to adjust an in-plane film thickness distribution of the thin film; and a controller for outputting a control signal to execute a step of forming the thin film using the main precursor gas supply part and the reaction gas supply part, and subsequently a step of supplying the adjustment-purpose precursor gas from the adjustment-purpose precursor gas supply part to compensate for a film thickness of a portion having a relatively thin film thickness.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2017-214122, filed on Nov. 6, 2017, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a technique for stacking reaction products on a surface of a substrate by supplying process gases that react with each other onto the substrate.

BACKGROUND

As one of the methods for forming a thin film such as a silicon nitride film on a semiconductor wafer (hereinafter referred to as a “wafer”) which is a substrate, an atomic layer deposition (ALD) method of stacking reaction products on a surface of a wafer by sequentially supplying a precursor gas and a reaction gas onto the surface of the wafer is known. As a film-forming apparatus for performing a film-forming process using such an ALD method, for example, an apparatus in which a rotary table for revolving a plurality of wafers arranged in a circumferential direction is installed inside a vacuum container is known. In such a film-forming apparatus, a precursor gas supply region and a reaction gas supply region are formed so as to be spaced apart from each other in a rotational direction of the rotary table. The wafers pass through the precursor gas supply region and the reaction gas supply region in an alternate manner, thus forming films on the respective wafers.

Such a rotational film-forming apparatus has a tendency to degrade a film thickness distribution uniformity of the wafer in a revolution direction. For example, assuming that a wafer is divided into two regions in a line along the diameter of a circle which is a revolution orbit, a region where the film thickness is thinner than that of the other region appears at left and right sides of the line at the center of the circle.

One of the factors may be that, since a wafer mounting region is formed as a recess, a gas is introduced between the peripheral edge of the wafer and the inner peripheral wall of the recess and the influence of this gas differs in the circumferential direction of the wafer. In addition, even when the wafer W is placed on a flat surface without forming a recess, it is presumed that the same phenomenon occurs because a gas flow is disturbed near the peripheral end face of the wafer. Another factor may be the influence of plasma distribution based on the shape of an antenna and the like.

Although the film thickness of the relevant region is thinner than the film thickness of other regions, a film thickness difference is about several A, which is not a phenomenon affecting a yield. However, since miniaturization of pattern line width and three-dimensionalization of devices are progressing, there is a possibility that this phenomenon may become more apparent.

In addition, in a film-forming apparatus for forming a film by supplying a precursor gas and a reaction gas onto a revolving substrate, there has been proposed a technique for forming regions having an uniform concentration of a plasmarized reaction gas by setting an angle formed by a gas injector to be less than 180 degrees, thereby uniformizing the film thickness. However, with respect to the uniformity of plasma and a method of supplying a gas, it is difficult to cope with a slight difference in film thickness, which is caused by the structure of a film-forming apparatus, requiring further improvement.

SUMMARY

Some embodiments of the present disclosure provide a technique capable of providing high in-plane uniformity in film thickness when stacking reaction products on the surface of a substrate by supplying process gases that react with each other onto the substrate.

According to one embodiment of the present disclosure, there is provided a film-forming apparatus for forming a thin film by repeating a cycle a plurality of times, the cycle including supplying and adsorbing a precursor gas onto a substrate mounted on a mounting part inside a vacuum container and subsequently generating a reaction product by allowing the precursor gas absorbed onto the substrate to react with a reaction gas, the film-forming apparatus including: a main precursor gas supply part configured to supply the precursor gas; a reaction gas supply part configured to supply the reaction gas; at least one adjustment-purpose precursor gas supply part configured to supply an adjustment-purpose precursor gas to adjust an in-plane film thickness distribution of the thin film; and a controller configured to output a control signal so as to execute a step of forming the thin film on the substrate using the main precursor gas supply part and the reaction gas supply part, and subsequently a step of supplying the adjustment-purpose precursor gas from the at least one adjustment-purpose precursor gas supply part to compensate for a film thickness of a portion having a relatively thin film thickness as compared to other portions in the thin film.

According to another embodiment of the present disclosure, there is provided a method of forming a thin film using a film-forming apparatus for forming a film by repeating a cycle a plurality of times, the cycle including supplying and adsorbing a precursor gas from a main precursor gas supply part onto a substrate mounted on a mounting part inside a vacuum container, supplying a reaction gas from a reaction gas supply part, and allowing the precursor gas absorbed on the substrate to react with the reaction gas to produce a reaction product, the method including: forming a thin film on the substrate using the main precursor gas supply part and the reaction gas supply part; and subsequently, supplying an adjustment-purpose precursor gas from an adjustment-purpose precursor gas supply part to compensate for a film thickness of a portion having a relatively thin film thickness as compared to other portions in the thin film.

DETAILED DESCRIPTION

First Embodiment

A film-forming apparatus according to a first embodiment will be described. As shown inFIGS. 1 and 2, the film-forming apparatus includes a vacuum container1having a substantially-circular planar shape, and a rotary table2which is installed inside the vacuum container1to revolve a wafer W. A rotational center C of the rotary table2coincides with the center of the vacuum container1. The rotary table2is made of, for example, quartz. The vacuum container1includes a top plate portion11and a container body12. The top plate portion11is configured to be attachable to and detachable from the container body12. A separation gas supply pipe74for supplying a nitrogen (N2) gas as a separation gas is connected to the central portion of an upper surface of the top plate portion11. This prevents different process gases from mixing with each other at the central portion inside the vacuum container1,

The rotary table2is fixed to a substantially cylindrical core portion21at the central portion of the rotary table2. The rotary table2is configured to be rotatable around a vertical axis, in this example, counterclockwise when viewed from above, with the rotational center C inFIG. 2as a center, by a rotary shaft22which is connected to a lower surface of the core portion21and extends in the vertical direction. Reference numeral23inFIG. 1denotes a rotation mechanism for rotating the rotary shaft22around the vertical axis. Further, an encoder20is connected to the rotation mechanism23and is configured to transmit an encoder value indicating a rotational angle of the rotary table2to a control part100to be described later. A N2gas as a purge gas is supplied from a purge gas supply pipe72to the periphery of the rotary shaft22and the rotation mechanism23.

In an upper surface of the rotary table2are formed four circular recesses24in which the wafers W are accommodated respectively, along the circumferential direction (rotational direction) of the rotary table2. Further, a heater7, which is a temperature adjustment part for adjusting a temperature of the rotary table2to heat the wafers W mounted on the rotary table2to, for example, 450 degrees C., is concentrically installed at the bottom portion of the vacuum container1. Reference numeral73inFIG. 1denotes a purge gas supply pipe for supplying a N2gas as a purge gas to a region where the heater7is installed.

As shown inFIG. 2, a transfer port16through which a wafer W is transferred is formed in the side wall of the vacuum container1. The transfer port16is opened and closed by a gate valve17. Three lift pins (not shown) for pushing up the wafer W mounted on the rotary table2from below are arranged below the rotary table2at equal intervals in the circumferential direction of the wafer W in a region facing the transfer port16inside the vacuum container1. Holes are formed in the bottom of each of the recesses24so as to correspond to the three lift pins. When loading and unloading the wafer W, the rotary table2sequentially stops at a position where the holes of the recess24and the lift pins face each other in the vertical direction. The wafer W is delivered between the outside of the vacuum container1and the interior of the recess24via the transfer port16in cooperation between a substrate transfer mechanism (not shown) installed outside the film-forming apparatus and the lift pins.

As shown inFIG. 2, assuming that the rotational direction (counterclockwise direction in this example) of the rotary table2is a forward side and a direction (clockwise direction in this example) opposite to the rotational direction is a backward side, a gas supply/exhaust unit4for supplying a dichlorosilane (DCS) gas as a precursor gas toward the wafer W revolving by the rotary table2, a reaction gas nozzle51for supplying a mixture of an NH3gas as a reaction gas and a H2gas toward the revolving wafer W, and a modifying gas nozzle52for supplying a H2gas as a modifying gas toward the revolving wafer W are installed above the rotary table2in that order along the rotational direction toward the forward side. In the following description, a rotational direction of the wafer W is referred to as a forward side of the wafer W and a direction opposite to the rotational direction of the wafer W is referred to as a backward side of the wafer W. In this example, the gas supply/exhaust unit4is used as both a main precursor gas supply part and an adjustment-purpose precursor gas supply part. The reaction gas nozzle51corresponds to a reaction gas supply part.

The gas supply/exhaust unit4will be described with reference toFIG. 3which is a bottom view andFIG. 4which is a longitudinal sectional side view. The gas supply/exhaust unit4includes a prismatic main body40provided so as to extend from a peripheral edge side of the rotary table2toward a central side thereof. As shown inFIG. 1, the gas supply/exhaust unit4is fixed to the lower surface of the top plate portion11by a support portion40aformed on an upper surface of the main body40. As shown inFIGS. 3 and 4, DCS gas discharge ports41for supplying a DCS gas, slit-like exhaust ports42formed in a lattice shape to surround the DCS gas discharge ports41, and a separation gas discharge port43for discharging a separation gas such as argon (Ar) gas or the like, which is formed around the exhaust ports42, are formed in the lower surface of the main body40. InFIG. 3, the exhaust ports42and the separation gas discharge port43are shown in thick lines.

The DCS gas discharge ports41are formed at equal intervals in the longitudinal direction of the main body40over a range traversing a passage region through which the wafer W passes. Of the DCS gas discharge ports41, DCS gas discharge ports41for discharging the DCS gas toward a region of the central side of the rotary table2are referred to as central-side gas discharge ports411, and DCS gas discharge ports41for discharging the DCS gas toward a region of the peripheral side of the rotary table2are referred to as peripheral-side gas discharge ports412. InFIG. 3, the central-side gas discharge ports411are shown by hatching.

As shown inFIG. 4, the central-side gas discharge ports411and the peripheral-side gas discharge ports412are respectively connected to one ends of a central-side gas supply passage441and a peripheral-side gas supply passage442, which are configured to supply gases independently of each other. Each of the other ends of the central gas supply passage441and the peripheral gas supply passage442circulate through the interiors of the main body40and the support portion40a, penetrate the top plate portion11in the thickness direction to be drawn outside the vacuum container1, and is connected to one end of a DCS gas supply pipe48. A DCS gas supply source49is connected to the other end of the DCS gas supply pipe48. A central-side valve V441and a peripheral-side valve V442are respectively installed in the central-side gas supply passage441and the peripheral-side gas supply passage442. A mass flow controller (MFC)50is installed in the DCS gas supply pipe48. Further, a flow rate adjustment part (not shown) is installed in each of the central-side gas supply path441and the peripheral-side gas supply path442. The flow rate adjustment part adjusts a flow rate of the DCS gas discharged from the peripheral-side gas discharge ports412to be larger than that of the DCS gas discharged from the central-side gas discharge ports411, when opening both the central-side valve V441and the peripheral-side valve V442to supply the DCS gas.

By opening and closing the central-side valve V441and the peripheral-side valve V442, respectively, the supply of gases from the central-side gas discharge ports411and the peripheral-side gas discharge ports412is switched on and off. Further, the flow rates of the DCS gas supplied from the central-side gas discharge ports411and the peripheral-side gas discharge ports412are set by adjusting the flow rate of the DCS gas with the mass flow controller (MFC)50. Therefore, the central-side valve V441, the peripheral-side valve V442and the MFC50correspond to a flow rate adjustment part.

The exhaust ports42are connected to an exhaust flow path45which is formed independently from the central-side gas supply path441and the peripheral-side gas supply path442inside the main body40. The DCS gas or the separation gas supplied to the lower surface side of the gas supply/exhaust unit4flows into one end side of the exhaust flow path45via the exhaust ports42. Further, the exhaust flow path45is formed so as to penetrate the interior of the support portion40aand the top plate portion11. An exhaust part90is connected to the other end side of the exhaust flow path45. InFIG. 4, reference numeral V45denotes a valve for switching an ON-OFF operation of the exhaust.

As shown inFIG. 4, the separation gas discharge port43is connected to one end of a separation gas flow path46formed independently from the central-side gas supply passage441, the peripheral-side gas supply passage442and the exhaust flow path45. The other end of the separation gas flow path46penetrates the interiors of the support portion40aand the top plate portion11and is coupled to a separation gas supply source47via a valve V46and a flow rate adjustment part M46.

Accordingly, when exhausting the DCS gas and the separation gas from the exhaust ports42while discharging the gases, a region surrounded by a curtain of an air flow of the separation gas is defined below the gas supply/exhaust unit4. Thus, a region to which the DCS gas is discharged and a region outside the separation gas discharge port43are defined. The DCS gas supplied to the region surrounded by the curtain of the air flow of the separation gas is exhausted together with the separation gas from the exhaust ports42.

Returning toFIG. 2, the reaction gas nozzle51and the modifying gas nozzle52have substantially the same configuration except that gases to be discharged are different. Each of the reaction gas nozzle51and the modifying gas nozzle52is configured as an elongated tubular body with its distal end closed. Each of the reaction gas nozzle51and the modifying gas nozzle52is installed to extend horizontally from the side wall of the vacuum container1toward the center of the rotary table2and intersect the passage region of the wafer W above the rotary table2. At the forward side in the rotational direction of the rotary table2, gas discharge ports51aand52afor discharging gases therethrough are respectively formed in lateral surfaces of the reaction gas nozzle51and the modifying gas nozzle52step by step in the lengthwise direction.

One end of a reaction gas supply pipe53is connected to a proximal end of the reaction gas nozzle51. The other end of the reaction gas supply pipe53is coupled to an NH3gas supply source56filled with an ammonia (NH3) gas. One end of a hydrogen (H2) gas supply pipe55is connected to the reaction gas supply pipe53. A H2gas supply source57is connected to the other end of the H2gas supply pipe55. One end of a modifying gas supply pipe54is connected to a proximal end of the modifying gas nozzle52. A H2gas supply source58filled with a H2gas is connected to the other end of the modifying gas supply pipe54. InFIG. 2, reference numerals V53, V54and V55denote valves installed in the reaction gas supply pipe53, the modifying gas supply pipe54and the H2gas supply pipe55, respectively. Reference numerals M53, M54and M55denote flow rate adjustment parts installed in the reaction gas supply pipe53, the modifying gas supply pipe54and the H2gas supply pipe55, respectively.

Further, a plasma generating part81is installed above a region extending from the respective positions of the reaction gas nozzle51and the modifying gas nozzle52in the top plate portion11to the forward side. As shown inFIGS. 1 and 2, the plasma generating part81is formed by winding an antenna83made of, for example, a metal wire in a coil shape, and is housed in a housing80made of, for example, quartz or the like. The antenna83is coupled to a high frequency power supply85having a frequency of 13.56 MHz and an output power of, for example, 5,000 W, through a connection electrode86having a matching device84disposed therein. In the figures, reference numeral82denotes a Faraday shield for shielding an electric field generated from the high frequency generating part, and reference numeral87denotes slits for allowing a magnetic field generated from the high frequency generating part to reach the wafer W. Reference numeral89denotes an insulating plate installed between the Faraday shield82and the antenna83.

In a processing space defined above the rotary table2, a region below the gas supply/exhaust unit4corresponds to an adsorption region where the DCS gas is adsorbed. A region defined below the reaction gas nozzle51corresponds to a reaction region where the DCS gas is nitrided. A region defined below the plasma generating part81installed to correspond to the modifying gas nozzle52corresponds to a modification region in which a SiN film is modified by plasma.

Further, a separation region60is formed in a region of the backward side of the modifying gas nozzle52and the forward side of the plasma generating part81installed to correspond to the reaction gas nozzle51in the rotational direction of the rotary table2. A ceiling surface of the separation region60is set to be lower than a ceiling surface on which the plasma generating part81is installed. The separation region60is provided to prevent an NH3gas supplied to the backward side in the rotational direction of the rotary table2with respect to the separation region60from being diluted by mixing with a gas supplied to the forward side in the rotational direction with respect to the separation region60. In addition, since the gas supply/exhaust unit4can also form a curtain of the separation gas so as to intersect the passage region of the wafer W, it can be said that the separation gas supplied from the gas supply/exhaust unit4prevents a gas supplied from the reaction gas nozzle51from being diluted by a gas supplied from the modifying gas nozzle52.

Further, as shown inFIG. 2, exhaust ports61and62are respectively opened outside the rotary table2at the forward sides of the reaction gas nozzle51and the modifying gas nozzle52when viewed in the rotational direction of the rotary table2. Reference numeral64inFIG. 1denotes an exhaust device which is constituted by a vacuum pump or the like, and is coupled to the exhaust ports61and62via an exhaust pipe.

As shown inFIG. 1, the film-forming apparatus is provided with a control part100including a computer for controlling the overall operation of the apparatus. Referring also toFIG. 5, the control part100includes a CPU101, a memory102and a program storage part103in which a program for executing a group of steps according to a wafer film-forming process and a film thickness adjusting process which will be described later. In the figure, reference numeral104denotes a bus. In addition, the control part100is configured to receive an encode value indicating a rotational angle of the rotary table2, which is read by the encoder20. Further, the control part100is configured to output a control signal for controlling the rotation mechanism23to control the rotation of the rotary table2and also output a control signal for controlling the opening and closing of the central-side valve V441and the peripheral-side valve V442to switch the supply and cutoff of the DCS gas discharged from the DCS gas discharge ports41. Furthermore, the control part100is configured to output a control signal for controlling the MFC50to adjust the flow rate of the DCS gas. Incidentally, even when switching the supply of the DCS gas to the OFF state to set the flow rate of the DCS gas to zero, it is included in the adjustment of the flow rate.

The memory102stores a data table in which an encoder value of the rotary table2, which indicates the correspondence between the position of the gas supply/exhaust unit4and the position of the wafer W when the DCS gas is supplied onto the wafer W in the film thickness adjusting process to be described later, a DCS gas supply amount, and the supply and cutoff of the gases discharged from the central-side gas discharge ports411and the peripheral-side gas discharge ports412, are associated with each other.

Data of the data table will be described with reference toFIGS. 6 and 7. The supply flow rate of DCS gas, which is set by the MFC50, is assumed to be adjusted constantly.FIG. 6schematically shows an example of a film thickness distribution on a surface of a wafer W after a film-forming process to be described later is performed on the wafer W using the film-forming apparatus according to the first embodiment. As shown inFIG. 6, for example, the wafer W may have portions200and201. The portion200is formed near the center of the rotary table2at the peripheral edge of the wafer W at the forward side, and the portion201is formed near the center of the rotary table at the peripheral portion of the wafer W at the backward side. Each of the portions200and201has a small thickness of about 1 Å. For this reason, a film thickness of the wafer W subjected to the film-forming process is measured in advance. A data table is prepared to supply a precursor gas to a portion where the film thickness becomes thin in the film-forming process in a film thickness adjusting process (film thickness adjustment) performed subsequent to the film-forming process.

Dashed lines θa to θd inFIG. 6indicate positions of the gas supply/exhaust unit4when the rotational angle of the rotary table2is θ1to θ4. Values of the encoder when the rotational angle of the rotary table2is θ1to θ4are assumed to be n1to n4, respectively. For example, before the rotational angle of the rotary table2reaches θ1, the gas supply/exhaust unit4is in front of the wafer W and does not reach above the wafer W. Thus, it is not necessary to supply the DCS gas. Therefore, as shown inFIG. 7, the data table is prepared so that the central-side valve V441is closed and the peripheral-side valve V442is closed with respect to an encoder value (˜n1) before the rotational angle reaches θ1.

Subsequently, when the rotational angle of the rotary table2falls within a range of θ1to θ2, the gas supply/exhaust unit4is located above a region near the forward side in the wafer W. At this time, as shown inFIG. 6, the central-side gas discharge ports411is located above the portion200having a relatively thin film thickness, which is formed near the forward side in the wafer W, and the peripheral-side gas discharge ports412is located at a position spaced apart from above the portion200. Therefore, it is only necessary to supply the DCS gas from the DCS gas discharge ports41arranged close to the center of the rotary table2in the gas supply/exhaust unit4. Thus, as shown inFIG. 7, the data table is prepared so that the central-side valve V441is opened and the peripheral-side valve V442is closed with respect to the encoder values n1to n2when the rotational angle falls within a range of θ1to θ2.

Subsequently, when the rotational angle of the rotary table2falls within a range of θ2to θ3, the gas supply/exhaust unit4is located above a region where film formation is uniformly performed in the film-forming process. This eliminates the need to supply the DCS gas. Therefore, the data table is prepared so that the central-side valve V441is closed and the peripheral-side valve V442is closed with respect to the encoder values n2to n3when the rotational angle falls within a range of θ2to θ3.

When the rotational angle of the rotary table2falls within a range of θ3to θ4, the central-side gas discharge ports411are located above the portion201having a relatively thin film thickness near the backward side in the wafer W, and the peripheral-side gas discharge ports412are located at a position spaced apart from above the portion201. Accordingly, as shown inFIG. 7, the data table is prepared so that the central-side valve V441is opened and the peripheral-side valve V442is closed with respect to the encoder values n3to n4when the rotational angle falls within a range of θ3to θ4. Further, before the rotational angle of the rotary table2reaches θ4, as shown inFIG. 7, the data table is prepared so that the central-side valve V441is closed and the peripheral-side valve V442is closed with respect to an encoder value (n4˜) after the rotational angle reaches θ4.

Likewise, even at the rotational angle at which the gas supply/exhaust unit4is located above another wafer W mounted on the rotary table2, in order to supply the DCS gas to a thin portion of the film formed on the wafer W in a limited manner, a data table is created so that an encoder value corresponding to the rotational angle of the rotary table2is associated with the opening/closing of the central-side valve V441and the peripheral-side valve V442.

Then, a program starts each step of the film thickness adjusting process after executing each step of the film-forming process (to be described later), and reads the supply amount of the DCS gas and the opening/closing data of the central-side valve V441and the peripheral-side valve V442from the data table in accordance with the encoder values of the rotary table2while rotating the rotary table2. Further, the program outputs control signals to the MFC50, the central-side valve V441and the peripheral-side valve V442to operate them to supply a precursor gas in the film thickness adjusting process. The program is stored and installed on a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, a flexible disk or the like.

The operation of the first embodiment will be described below. First, the gate valve17is opened. Four wafers W are delivered on the respective recesses24of the rotary table2in cooperation between the lift pins and the substrate transfer mechanism as described previously, while rotating the rotary table2intermittently. Subsequently, the gate valve17is closed to make the interior of the vacuum container1airtight. The wafers W mounted on the respective recesses24are heated to, for example, 500 degrees C. or higher, specifically 550 degrees C., by the heater7. Then, the interior of the vacuum container1is kept in a vacuum atmosphere of a pressure of, for example, 2 torr (266.6 Pa) by the exhaust performed from the exhaust ports61and62. The rotary table2is rotated clockwise at a rotation speed of 1 to 300 rpm, specifically 30 rpm.

Then, an NH3gas and a H2gas are supplied from the reaction gas nozzle51, and a H2gas is supplied from the modifying gas nozzle52. While each gas is being supplied in this manner, a high frequency is supplied from the plasma generating part81. With this high frequency, plasma of the H2gas and the NH3gas supplied from the reaction gas nozzle51is generated, and plasma of the H2gas supplied from the modifying gas nozzle52is generated. In the gas supply/exhaust unit4, both the central-side valve V441and the peripheral-side valve V442are opened to supply a DCS gas from all the DCS gas discharge ports41. An Ar gas is discharged from the separation gas discharge port43, and the exhaust is performed from the exhaust ports42.

Further, when a wafer W is located below the gas supply/exhaust unit4by rotating the rotary table2, the DCS gas is supplied and adsorbed onto the surface of the wafer W. When the wafer W reaches below the reaction gas nozzle51by further rotating the rotary table2, DCS adsorbed onto the wafer W reacts with NH3to generate SiN which is a reaction product. Chlorine (Cl) remaining on the wafer W is removed by active species of hydrogen produced when the H2gas supplied to the respective region is plasmarized.

When the wafer W reaches below the modifying gas nozzle52by further rotating the rotary table2, Cl remaining on the wafer W is removed by active species of hydrogen in a similar manner. Thereafter, the wafer W enters below the gas supply/exhaust unit4and the DCS is again adsorbed onto the wafer W.

In this way, as the rotary table2continuously rotates, the wafers W repeatedly pass a plurality of times below the gas supply/exhaust unit4, below the reaction gas nozzle51and below the modifying gas nozzle52in this order. As a result, SiN is deposited on the surface of each wafer W, thereby increasing a film thickness of the SiN film and modifying the SiN film.

While the wafer W is revolving in this way, the film-forming process of forming the SiN film on the entire surface of the wafer is performed. At this time, in the film-forming process, the SiN film formed on the wafer W has the portions200and201having a relatively thin film thickness of about 1 Å, which are formed at the central side of the rotary table2in the peripheral edges at the forward and backward sides in the wafer W as shown inFIG. 6. The portions200and201are formed due to turbulence of air flow, non-uniformity of plasma during a plasma process and the like, which depend on a shape of the recess that receives the wafer W.

For this reason, the film thickness adjusting process of supplying a gas toward such a thin film thickness portion in the wafer W to form a film, is performed. First, the central-side valve V441and the peripheral-side valve V442are closed to stop the discharge of the DCS gas in the gas supply/exhaust unit4. At this time, the generation of plasma by the plasma generating part81and the supply of gases from the reaction gas nozzle51and the modifying gas nozzle52are continued.

Further, the rotation speed of the rotary table2is lowered to, for example, 1 rpm. The rotation of the rotary table2in the film thickness adjusting process may be a step operation (index) in which the rotation of a very small angle and the stop of the rotary table2are alternately repeated. Further, according to the rotational angle of the rotary table2, namely an encoder value obtained when the rotary table2is rotated in this example, the opening/closing data of the central-side valve V441and the peripheral-side valve V442for controlling the supply and cutoff of the gases discharged from the central-side gas discharge ports411and the peripheral-side gas discharge ports412, is read from the data table shown inFIG. 7. InFIGS. 8 to 12, symbol O is attached to a respective valve when each of the central-side valve V441and the peripheral-side valve V442is opened, and symbol C is attached to a respective valve when the respective valve is closed. The closed valve is also shown by hatching. In addition, dots are attached to the portions200and201having a relatively thin film thickness in the wafer W. A region where a precursor gas is adsorbed in the film thickness adjusting process is shown by hatching.

For example, before the rotational angle of the rotary table2reaches θ1, the gas supply/exhaust unit4is located in front of the wafer W, as shown inFIG. 8. Since the encoder value at this time is n1or less, as shown in the data table ofFIG. 7, a control signal for closing the central-side valve V441and closing the peripheral-side valve V442is outputted from the control part100so that a flow rate of the DCS gas discharged from each DCS gas discharge port41is zero.

When the rotational angle of the rotary table2exceeds θ1by further rotating the rotary table2, namely falls within a range of θ1to θ2, as shown inFIG. 9, a peripheral edge portion of the forward side in the wafer W is located below the gas supply/exhaust unit4. At this time, in the gas supply/exhaust unit4, the central-side gas discharge ports411are located above the portion200having a relatively thin film thickness in the wafer W, and the peripheral-side gas discharge ports412are located above a region spaced apart from the portion200having a relatively thin film thickness in the wafer W.

At this time, since the encoder value falls within a range of n1to n2, the control part100outputs a control signal for opening the central-side valve V441and closing the peripheral-side valve V442, as shown in the data table ofFIG. 7. Therefore, as shown inFIG. 9, when the rotational angle of the rotary table2falls within a range of θ1to θ2, a DCS gas is discharged from the DCS gas discharge ports41near the center of the rotary table2in the gas supply/exhaust unit4. The DCS gas is supplied toward a portion below the DCS gas discharge ports41in the wafer W, namely the portion200having a relatively thin film thickness, which is located near the center of the rotary table2at the forward side in the wafer W. Further, no precursor gas is supplied to a portion having a sufficient thick film thickness at the forward side of the wafer W in the peripheral edge side of the rotary table2.

Subsequently, when the rotational angle of the rotary table falls within a range of θ2to θ3as shown inFIG. 10by further rotating the rotary table2, the gas supply/exhaust unit4is located in a region near the center of the wafer W. In the region, the film thickness is thick and uniform in the film-forming process. At this time, since the encoder value falls within a range of n2to n3, the control unit100outputs a control signal for closing the central-side valve V441and closing the peripheral-side valve V442. Therefore, when the rotational angle of the rotary table2falls within a range of θ2to θ3, the flow rate of the DCS gas discharged from each DCS gas discharge ports41is zero. That is to say, no DCS gas is discharged. Therefore, no DCS gas is adsorbed onto a region having a uniform film thickness near the center of the wafer W.

Subsequently, when the rotational angle of the rotary table2falls within a range of θ3to θ4as shown inFIG. 11by further rotating the rotary table2, a peripheral edge portion of the backward side of the wafer W is located below the gas supply/exhaust unit4. At this time, in the gas supply/exhaust unit4, the central-side gas discharge ports411are located above the portion201having a relatively thin film thickness in the wafer W, and the peripheral-side gas discharge ports412are located above a region spaced apart from the portion201having a relatively thin film thickness in the wafer W.

When the rotational angle of the rotary table2falls within a range of θ3to θ4, the encoder value falls within a range of n3to n4. Thus, the control unit100outputs a control signal for opening the central-side valve V441and closing the peripheral-side valve V442. As a result, the DCS gas is supplied and adsorbed onto the portion201having a relatively thin film thickness, which is located near the center of the rotary table2at the peripheral edge of the backward side of the wafer W. Further, no DCS gas is discharged and adsorbed onto a region near the peripheral edge of the rotary table2in the peripheral edge of the backward side of the wafer W.

As shown inFIG. 12, when the rotational angle of the rotary table2exceeds θ4, the encoder value exceeds n4. Therefore, the control unit100outputs a control signal for closing the central-side valve V441and closing the peripheral-side valve V442so that a flow rate of the DCS gas discharged from each DCS gas discharge port41becomes zero.

Subsequently, when further rotating the rotary table2, the wafer W passes below the reaction gas nozzle51and below the modifying gas nozzle52in this order. Thus, the DCS gas adsorbed onto the wafer W reacts with NH3to form SiN. In the film thickness adjusting process, since the DCS gas is adsorbed only onto the central region of the rotary table2in each of the forward-side peripheral edge and the backward-side peripheral edge of the wafer W, the DCS gas reacts with an NH3gas only in the respective region to form SiN.

The forward-side peripheral edge portion and the backward-side peripheral edge portion of the wafer W at the central side of the rotary table2are the portions200and201having a relatively thin film thickness in the film-forming process as described above. Thus, the film-forming process can be limitedly performed so as to compensate for the film thickness of the portions200and201having a relatively thin film thickness when being subjected the film-forming process. Likewise, with respect to another wafer W, the film thickness is compensated by adsorbing the DCS gas onto a portion having a relatively thin thickness in the wafer W.

According to the above-described embodiment, in the film-forming apparatus that supplies a gas toward a wafer W to form a film on the wafer W, a DCS gas and an NH3gas are alternately supplied onto the revolving wafer W to perform the film-forming process. Further, in the film thickness adjusting process, the central-side valve V441and the peripheral-side valve V442are operated based on the rotational angle of the rotary table2so that the supply and cutoff of the DCS gas discharged from the central-side gas discharge ports411and the peripheral-side gas discharge ports412in the gas supply/exhaust unit4is adjusted. Therefore, the DCS gas can be limitedly attached onto the portions200and201having a relatively thin film thickness in a film of the wafer W, which is formed by the film-forming process. It is therefore possible to compensate for the film thickness of the portions200and201having a relatively thin film thickness in the film-forming process. This improves the film thickness uniformity of a film formed on the wafer W.

Further, in the present disclosure, the film thickness adjusting process may include a step of supplying a film thickness adjusting gas to the wafer W and a step of supplying a reaction gas. The steps may be repeated in plural cycles. Further, in the film thickness adjusting process, a flow rate of the MFC50may be adjusted. In this case, a set value of the flow rate of the MFC in the data table shown inFIG. 7may be changed according to an encoder value.

In the above-described embodiment, the DCS gas discharge ports41are divided into two groups of the central-side gas discharge ports411and the peripheral-side gas discharge ports412. However, the DCS gas discharge ports41may be divided into three or more groups, and flow rate levels of the groups may be adjusted independently of each other. Further, the flow rate of DCS gas supplied from each of the DCS gas discharge ports41may be individually adjusted so that the horizontal distribution of the gas flow rates can be adjusted. In this case, in the film thickness adjusting process, a flow rate of the DCS gas discharged from a DCS gas discharge port41, corresponding to a portion where the film thickness is limitedly increased, may be set to be larger than that of the DCS gas supplied from the other DCS gas discharge ports41. Incidentally, adjusting the flow rate of a gas encompasses a case where the flow rate of a gas discharged from the DCS gas discharge ports41is set to zero.

With the above configuration, it is possible to supply the precursor gas at a large amount limitedly to a portion having a relatively thin film thickness in a film formed by the film-forming process, and to compensate for the film thickness of a portion having a relatively thin film thickness in the wafer W by the film-forming process, in the film thickness adjusting process. This provides the same effects as those in the above embodiment.

In some embodiments, the film thickness adjusting process may include stopping the movement of the wafer W, supplying a precursor gas, temporarily stopping the supply of the precursor gas, resuming the movement of the wafer W, changing gas discharge ports for discharging a gas, changing a position at which the precursor gas is adsorbed on the wafer W, stopping the rotation of the rotary table2, and supplying the precursor gas.

Alternatively, for example, gas discharge ports may be dispersedly formed over the entire lower surface of a disk-shaped gas supply part to supply a gas to the entire surface of the wafer W. In this case, when performing the film thickness adjusting process, a flow rate of DCS gas discharged from the gas discharge ports may be adjusted.

In some embodiments, the present disclosure may be applied to a single wafer type film-forming apparatus in which a gas is supplied toward a single substrate mounted on a mounting table to form a film. For example, as shown inFIG. 13, a mounting table91is installed inside a vacuum container9. A shower head409serving as a gas supply part for supplying a gas toward the entire surface of the wafer W is installed so as to face the wafer W mounted on the mounting table91. Further, an exhaust port92is formed in the vacuum container9. An exhaust device64is connected to the exhaust port92via an exhaust pipe94.

In some embodiments, a plurality of gas discharge ports may be arranged dispersedly in the lower surface of the shower head409, and the lower surface of the shower head409may be divided into a plurality of regions. Discharge of gas may be switched for each region. In this example, one end of a gas supply pipe93is connected to the shower head409, and the other end of the gas supply pipe93branches into two ends to which the DCS gas supply source49and the NH3gas supply source56are respectively connected. Reference numerals V49and V56inFIG. 13denote valves.

In such a film-forming apparatus, a film-forming process is performed by supplying a precursor gas onto the entire surface of the wafer W and allowing the precursor gas to react with a reaction gas. Subsequently, in a film thickness adjusting process, in order to adjust the film thickness, a film thickness adjustment-purpose precursor gas may be discharged only to a region corresponding to a portion having a relatively thin film thickness in the wafer W by the film-forming process.

Further, the present disclosure may be applied to a film-forming apparatus in which a substrate is linearly moved, and a precursor gas and a reaction gas are supplied toward a movement region of the substrate.

Further, after the wafer W is subjected to the film-forming process, a film thickness distribution of the wafer W may be measured using, for example, a Fourier transform infrared spectrophotometer (FT-IR). Based on data of the film thickness distribution measured for each wafer W, an encoder value and DCS gas discharge ports41for discharging a DCS gas may be set so that the DCS gas can be limitedly supplied toward a portion having a relatively thin film thickness. In this way, the film thickness adjusting process may be performed.

Further, a precursor gas supply part may be configured to supply a purge gas from DCS gas discharge ports41which supply no DCS gas. Furthermore, a separation gas discharge port and a discharge port may not be formed in the precursor gas supply part.

Second Embodiment

Further, the film-forming apparatus of the present disclosure may be configured to include a main precursor gas supply part that supplies a precursor gas when a film-forming process is performed on a wafer W, and a film thickness adjusting gas supply part that supplies a film thickness adjustment-purpose precursor gas to the wafer W.

For example, as shown inFIG. 14, a main gas supply/exhaust unit400for supplying a gas in the film-forming process is installed between the plasma generating part81corresponding to the reaction gas nozzle51and the modifying gas nozzle52in the film-forming apparatus shown inFIG. 2. An auxiliary gas supply/exhaust unit410having the same configuration as the gas supply/exhaust unit4shown inFIGS. 3 and 4is installed at the forward side of the modifying gas nozzle52. In this example, since a separation gas for separating a gas supplied from the reaction gas nozzle51and a gas supplied from the modifying gas nozzle52from each other can be supplied from the main gas supply/exhaust unit400, the separation region60is removed.

As shown inFIGS. 14 and 15, the main gas supply/exhaust unit400is formed in a fan shape extending in the circumferential direction of the rotary table2from the central side of the rotary table2toward the peripheral side when viewed from top. The lower surface of the gas supply/exhaust unit4is close and faces the upper surface of the rotary table2.

As shown inFIG. 15, gas discharge ports41, an exhaust port42and a separation gas discharge port43are opened in the lower surface of the main gas supply/exhaust unit400. The gas discharge ports41can discharge a DCS gas downward in the form of a shower onto the surface of the wafer W during rotation of the rotary table2in the film-forming process. Therefore, the main gas supply/exhaust unit400can supply a gas over a wider range than the auxiliary gas supply/exhaust unit410.

Further, in the main gas supply/exhaust unit400, three sections401,402and403are set from the central side of the rotary table2toward the peripheral edge side of the rotary table2. A DCS gas can be independently supplied to each of the gas discharge ports41formed dispersedly in the respective sections401,402and403. Therefore, for example, the flow rate of gas is adjusted so that it increases toward the peripheral edge side of the rotary table2. Further, the exhaust port42and the separation gas discharge port43are formed to exhaust a gas and discharge a purge gas independently of each other, similarly to the gas supply/exhaust unit4shown inFIGS. 3 and 4.

In forming a film on the wafer W using the film-forming apparatus configured as above, for example, the discharge of a precursor gas and a purge gas from the main gas supply/exhaust unit400is started, and the exhaust is started. As in the first embodiment, a reaction gas and a reforming gas are discharged to excite plasma. At this time, in the auxiliary gas supply/exhaust unit410, the discharge and exhaust of the purge gas is performed so that the central-side valve V441and the peripheral-side valve V442remain closed.

Then, the rotary table2is rotated at a rotation speed of, for example, 1 to 300 rpm. Thus, the DCS gas supplied from the main gas supply/exhaust unit400is adsorbed onto the wafer W and a film-forming process is performed. Thereafter, the discharge of the DCS gas in the main gas supply/exhaust unit400is stopped. Subsequently, the rotary table2is rotated at a rotation speed of 1 rpm or in a step operation (index), and an adjustment-purpose precursor gas is supplied by using the auxiliary gas supply/exhaust unit410, for example, in accordance with the data table shown inFIG. 7. In this way, a film thickness adjusting process is performed.

The main gas supply/exhaust unit400has a configuration in which a large number of DCS gas discharge ports41are formed in a fan-like wide range where the peripheral edge side of the rotary table2expands, and a flow rate can be adjusted independently for each of the section401, the section402and the section403, which are arranged side by side from the central side of the rotary table toward the peripheral edge side. Therefore, it is possible to precisely control the film thickness in the film-forming process, thereby improving the uniformity of the film thickness in the film-forming process. Further, by further adjusting the film thickness with the auxiliary gas supply/exhaust unit410, it is possible to further increase the uniformity of the film thickness.

In the film-forming apparatus according to the second embodiment, the adjustment-purpose precursor gas supply part may be configured to move above the wafer W to supply the precursor gas to a portion having a relatively thin film thickness. For example, as shown inFIG. 16, the film-forming apparatus according to the second embodiment may have the same configuration as the film-forming apparatus shown inFIG. 14, except that an adjusting gas supply nozzle422is replaced for the auxiliary gas supply/exhaust unit410.

The adjusting gas supply nozzle422is installed at, for example, at the distal end of a horizontally-extending support portion420and is configured to be swingable about a rotary shaft421. With this configuration, a position on the wafer W is changed by the rotation of the rotary table2and the swing of the adjusting gas supply nozzle422, and the precursor gas is supplied toward a portion where the film thickness is thinned on the wafer W in the film-forming process.

With such a configuration, it is possible to form a film so as to compensate for the film thickness of a portion where the film thickness is thinned on the wafer W in the film-forming process. This embodiment provides the same effects as those in the above embodiment.

Third Embodiment

Further, the present disclosure may be a film-forming apparatus provided with a plurality of precursor gas supply parts. For example, as shown inFIG. 17, two gas supply/exhaust units4A and4B having the same configuration as the gas supply/exhaust unit4shown inFIGS. 3 and 4may be arranged so as to face each other with the center of the rotary table2located between the gas supply/exhaust units4A and4B.

In such a film-forming apparatus, assuming that a film-forming process is performed on four wafers as shown inFIG. 17, in supplying a precursor gas in a film thickness adjusting process, when the precursor gas is supplied by one gas supply/exhaust unit4A (or4B) toward a portion having a relatively thin film thickness in the wafer W, the precursor gas can be supplied by the other gas supply/exhaust unit4B (or4A) toward a portion having a relatively thin film thickness in the wafer W, which is at a position opposed to one wafer W via the center of the rotary table2. Subsequently, the rotary table2may be rotated by 90 degrees to supply a gas from the gas supply/exhaust units4A and4B toward the remaining two wafers W. In this way, the film thickness adjusting process may be performed.

With such a configuration, in the film thickness adjusting process, the precursor gas can be supplied toward the plurality of wafers W at once. This shortens the time required to carry out the film thickness adjusting process on all the wafers W.

In a case where two portions where the film thickness is thinned in the film-forming process are formed, in the film thickness adjusting process, a precursor gas may be supplied from the gas supply/exhaust units4A and4B to the portions having different thin film thicknesses in the wafer W. For example, in the film thickness adjusting process, one gas supply/exhaust unit4A (or4B) may be formed at the central side of the rotary table2in the wafer W to supply the precursor gas to a portion having a relatively thin film thickness, and the other gas supply/exhaust unit4B (or4A) may be formed at the peripheral side of the rotary table2in the wafer W to supply the precursor gas to a portion having a relatively thin film thickness.

With this configuration, in the gas supply/exhaust units4A and4B, it is unnecessary to divide the gas discharge ports41for discharging the precursor gas into the central-side gas discharge ports411and the peripheral-side gas discharge ports412. For example, in the film-forming process, for one portion having a relatively thin film thickness, a gas is supplied from the central-side gas discharge ports411and no gas is supplied from the peripheral-side gas discharge ports412. On the other hand, for the other portion having a relatively thin film thickness, when no gas is supplied from the central-side gas discharge ports411but a gas is supplied from the peripheral-side gas discharge ports412, it is necessary to switch the DCS gas discharge ports41for discharging a precursor gas between the central-side gas discharge ports411and the peripheral-side gas discharge ports412to perform the discharge and cutoff of the gas. In this case, resolutions of a region to which the precursor gas is supplied and a region to which no precursor gas is supplied are lowered, which may make the boundary therebetween ambiguous.

Therefore, according to the above embodiments, in the gas supply/exhaust units4A and4B, since it is unnecessary to switch the DCS gas discharge ports41for discharging a precursor gas between the central-side gas discharge ports411and the peripheral-side gas discharge ports412, it is possible to perform a position control with high resolution of a region to which the precursor gas is supplied in the film thickness adjusting process.

According to the present disclosure in some embodiments, in forming a film on a substrate by supplying a precursor gas and a reaction gas reacting with the precursor gas on the substrate, a film-forming process is performed using a main precursor gas supply part and a reaction gas supply part. Thereafter, an adjustment-purpose precursor gas is supplied from an adjustment-purpose precursor gas supply part so as to compensate for a film thickness of a portion having a relatively thin film thickness. Accordingly, the in-plane uniformity of the film thickness of the film formed on the substrate is improved.