JP7540958B2 - Concentration control system, concentration control program, and concentration control method - Google Patents

Description

The present invention relates to a concentration control system, a concentration control program, and a concentration control method.

For example, as shown in Patent Document 1, a concentration control system for material gas used in semiconductor manufacturing processes is designed to control the two-dimensional concentration distribution of material gas supplied into a chamber that contains a substrate to a desired target concentration distribution.

Specifically, in this system, the internal space of the chamber is divided by a showerhead (a flat plate member with many small holes) into an upper space where the material gas is supplied, and a lower space where the substrate is housed, and the upper space is further divided into multiple rooms by partition plates. By making it possible to independently control the flow rate and concentration of the material gas to the supply areas set below each room, it is possible to control the two-dimensional concentration distribution of the material gas supplied to the lower space.

However, as a target concentration distribution, it may be necessary to make the concentration of material gas supplied from one supply area (hereinafter referred to as one supply area) higher than the concentration of material gas supplied from other supply areas; in other words, it may be necessary to have a peak in one supply area as a target concentration distribution.

However, some of the material gas supplied to another supply area adjacent to the first supply area flows into the first supply area, so if the flow rate supplied to the other supply area is changed, the peak that appeared in the first supply area will shift.

For this reason, in order to control the two-dimensional concentration distribution of the material gas to the desired target concentration distribution, the flow rate and concentration of the material gas supplied to each supply area must be controlled; however, these control parameters are not independent of each other and affect each other, making control extremely difficult.

JP 2019-192865 A

The present invention has been made to solve the above problems, and its main objective is to make it possible to control the two-dimensional concentration distribution of the material gas supplied to a chamber that houses a substrate to a desired target concentration distribution, for example one that has a peak.

In other words, the concentration control system according to the present invention is a concentration control system that controls the two-dimensional concentration distribution of a material gas supplied into a chamber that houses a substrate to a predetermined target concentration distribution, and is characterized in that it includes a material gas supply system provided corresponding to each of a plurality of supply areas set in the chamber, and a control device that controls the material gas supply system to control the two-dimensional concentration distribution to the target concentration distribution, and is configured to control the material gas supply system to adjust the material gas flow rate for each supply area, and then control the material gas supply system to adjust the material gas concentration for each supply area.

According to such a concentration control system, the peak of the two-dimensional concentration distribution can be moved to the position of the peak of the target concentration distribution by first adjusting the material gas flow rate for each supply area, and then, for example, by adjusting the material gas concentration for each supply area while keeping the material gas flow rate fixed, the peak concentration value can be changed without moving the position of the peak or while keeping the movement to a negligible extent. As a result, it is possible to control the two-dimensional concentration distribution of the material gas supplied to the chamber to the desired target concentration distribution.

A more specific example is when the target concentration distribution has a peak in one supply area, the control device adjusts the material gas flow rate in another supply area adjacent to the one supply area, thereby moving the peak of the two-dimensional concentration distribution within the one supply area.
With this configuration, the peak of the two-dimensional concentration distribution can be moved to the position of the peak of the target concentration distribution.

In order to more accurately control the two-dimensional concentration distribution to the target concentration distribution, it is preferable that the control device adjusts the material gas concentration for each supply area to control the calculated average concentration calculated in each supply area to approach the target average concentration for each supply area in the target concentration distribution.

In plasma processing, which is an example of the application of the present invention, the density distribution of the plasma generated in the chamber is not necessarily uniform, and for example, there may be a difference in plasma density between the center and the outer periphery of the chamber. In view of this, it may be necessary to have a peak in the center or the outer periphery of the chamber as the target concentration distribution of the material gas. Note that the need to have a peak of the target concentration distribution at a desired position is not necessarily limited to plasma processing, but is also required in various substrate processing such as plasmaless etching and CVD.
Therefore, it is desirable that the plurality of supply areas include a central area set in the center of the chamber and at least one annular area surrounding the central area.
With this configuration, the two-dimensional concentration distribution can have a peak in the center or annular area of the chamber.

It is preferable that the central area and the annular area are composed of a plurality of divided areas divided in the circumferential direction of the chamber, and the material gas supply system is provided corresponding to each of the plurality of divided areas.
In this case, since the central area and the annular area are divided into a plurality of divided areas, more precise control of the two-dimensional concentration distribution is possible.

A more specific embodiment is one in which the control device controls the material gas supply system to adjust the material gas concentration for each divided area, thereby controlling the two-dimensional concentration distribution to approach the target concentration distribution.

A specific example of a configuration for setting multiple supply areas is one in which the chamber has a chamber body having an internal space to which the material gas is supplied, a lid member that covers the internal space and has multiple supply ports formed therein corresponding to each of the supply areas, and a partition member that is provided on the internal space side of the lid member and separates the multiple supply ports.

In order to individually adjust the material gas flow rate and material gas concentration for each supply area, it is preferable that the gas supply system has a material gas supply line connected to each of the supply areas, a first fluid control device provided in each of the material gas supply lines, a dilution gas supply line connected to each of the material gas supply lines, and a second fluid control device provided in each of the dilution gas supply lines.

Examples of an embodiment for obtaining a two-dimensional concentration distribution include a laser emission mechanism that emits laser light from multiple locations around the chamber toward an entrance window formed in the peripheral wall of the chamber, a laser detection mechanism that detects each laser light that is emitted from the multiple locations, passes through the chamber, and exits from an exit window formed in the peripheral wall of the chamber, and a two-dimensional concentration distribution calculation unit that acquires a light intensity signal of each laser light detected by the laser detection mechanism and calculates a two-dimensional concentration distribution of the material gas in the chamber based on the light intensity signal.

The concentration control program according to the present invention is a program used in a concentration control system that controls the two-dimensional concentration distribution of a material gas supplied into a chamber that houses a substrate to a predetermined target concentration distribution, and the concentration control system includes a material gas supply system provided corresponding to each of a plurality of supply areas set in the chamber, and a control device that controls the material gas supply system to control the two-dimensional concentration distribution to the target concentration distribution, and is characterized in that the control device controls the material gas supply system to adjust the material gas flow rate for each supply area, and then controls the material gas supply system to adjust the material gas concentration for each supply area.

Furthermore, the concentration control method according to the present invention is a method for controlling the two-dimensional concentration distribution of a material gas supplied into a chamber that houses a substrate to a predetermined target concentration distribution, and is a concentration control method for controlling the two-dimensional concentration distribution to the target concentration distribution by controlling a material gas supply system provided corresponding to each of a plurality of supply areas set in the chamber, characterized in that the material gas supply system is controlled to adjust the material gas flow rate for each supply area, and then the material gas supply system is controlled to adjust the material gas concentration for each supply area.

These concentration control programs and methods can achieve the same effects as the concentration control system described above.

The present invention configured in this way makes it possible to control the two-dimensional concentration distribution of the material gas supplied to the chamber housing the substrate to a desired target concentration distribution.

FIG. 1 is a diagram illustrating a configuration of a concentration control system according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of a laser emission mechanism and a laser detection mechanism of the embodiment. FIG. 3 is a cross-sectional view showing the configuration of a chamber in the embodiment. FIG. 2 is an exploded perspective view showing the configuration of a chamber in the embodiment. FIG. 4 is a cross-sectional view showing a schematic diagram of an optical path formed in the chamber of the embodiment. FIG. 4 is a perspective view showing a configuration of a partition member of the embodiment. FIG. 2 is a functional block diagram showing functions of a control device according to the embodiment. 6 is a graph showing a target concentration distribution in the embodiment; 4 is a flowchart showing a concentration control operation of the control device of the embodiment. FIG. 11 is a perspective view illustrating a configuration of a partition member according to another embodiment. 10 is a flowchart showing a concentration control operation of a control device in another embodiment.

Below, one embodiment of the concentration control system according to the present invention will be described with reference to the drawings.

The concentration control system of this embodiment is used in the semiconductor manufacturing process and is useful for substrate processing such as etching of substrates such as wafers. This concentration control system may also be used for substrate processing such as film formation and cleaning of substrates.

1, the concentration control system 100 includes a chamber 10 that accommodates a substrate (not shown), a material gas supply line L1 that supplies a material gas such as _CH4 to the chamber 10, and a material gas exhaust line L2 that exhausts the material gas supplied to the chamber 10. Note that the material gas is not limited to _CH4 , and may be changed as appropriate to _SiF4 , _CFx , or the like.

The chamber 10 has an internal space S formed therein for accommodating a substrate, and a heater H is provided in this internal space S for heating the substrate. In this embodiment, the substrate is heated by the heater H, and a plasma is generated in the internal space S of the chamber 10 while a material gas is supplied to the chamber 10, thereby performing the substrate processing described above. Note that substrate processing does not necessarily require heating the substrate or generating plasma, and the chamber 10 may be used for various substrate processing, such as plasmaless substrate processing.

This chamber 10 is formed with multiple supply ports P1 through which the material gas is supplied and an exhaust port P2 through which the material gas supplied to the internal space S is exhausted.

One end of the material gas supply path L1 is connected to the above-mentioned supply port P1, and the other end is connected to the material gas source Z1. Here, a material gas supply path L1 is connected to each of the multiple supply ports P1, and these multiple material gas supply paths L1 are arranged in parallel with each other. This makes it possible to independently control the flow rate of the material gas flowing through each material gas supply path L1.

Each material gas supply line L1 is provided with one or more on-off valves V1 and a first fluid control device MFC1 that controls physical quantities such as the flow rate and pressure of the material gas. The first fluid control device MFC1 here is a differential pressure or thermal mass flow controller that controls the flow rate of the material gas flowing through the material gas supply line L1, calculates the actual flow rate flowing through the material gas supply line L1, and controls a fluid control valve (not shown) so that the actual flow rate approaches a pre-input target flow rate.

In addition, each material gas supply line L1 is connected to a dilution gas supply line L3 through which a dilution gas, such as nitrogen gas, flows to dilute the material gas, and these multiple dilution gas supply lines L3 are arranged in parallel with each other. This allows the flow rate of the dilution gas flowing through each dilution gas supply line L3 to be controlled independently.

Each dilution gas supply line L3 has one end connected to the material gas supply line L1 and the other end connected to a dilution gas source Z2, and is provided with one or more on-off valves V2 and a second fluid control device MFC2 that controls physical quantities such as the flow rate and pressure of the dilution gas. Like the first fluid control device MFC1 described above, the second fluid control device MFC2 here is a differential pressure or thermal mass flow controller that controls the flow rate of the dilution gas, and calculates the actual flow rate flowing through the dilution gas supply line L3 and controls a fluid control valve (not shown) so that the actual flow rate approaches a pre-input target flow rate.

One end of the material gas exhaust passage L2 is connected to the exhaust port P2 described above, and the other end is connected to, for example, a suction pump P located outside the chamber 10. This material gas exhaust passage L2 is provided with a pressure adjustment means V3 such as a pressure adjustment valve and an opening/closing valve V4.

As shown in FIG. 2, the concentration control system 100 of this embodiment further includes a laser emission mechanism 20 that emits laser light into the chamber 10 from multiple locations around the chamber 10, a laser detection mechanism 30 that detects each laser light emitted from the multiple locations and passing through the chamber 10, and a control device 40 that acquires a light intensity signal of each laser light detected by the laser detection mechanism 30 and controls the operation of the concentration control system 100.

First, the chamber 10 will be described in more detail. As shown in Figures 3 to 5, the chamber 10 of this embodiment has a chamber body 11 having the above-mentioned internal space S, an upper lid member 12 that covers the internal space S from above, a porous member 13 that is provided below the upper lid member 12 and has a large number of small holes h1 formed therein, and a lower lid member 14 that is provided below the porous member 13 and covers the internal space S from below.

As shown in FIG. 4, the chamber body 11 has an inner circumferential surface 111 that forms an internal space S having a shape of a rotating body, and an outer circumferential surface 112 on which an entrance window W1 and an exit window W2 that transmit the laser light are formed. In addition, one exhaust port P2 described above is formed in the center of the bottom wall of the chamber body 11. The number and arrangement of the exhaust ports P2 may be changed as appropriate.

The chamber body 11 of this embodiment has a polygonal outer peripheral surface 112, with an entrance window W1 formed on one of a pair of opposing sides of the outer peripheral surface 112 and an exit window W2 formed on the other. The outer peripheral surface 112 here is octagonal, with entrance windows W1 formed on half (four) of the consecutive sides and exit windows W2 formed on the remaining half (four) of the consecutive sides. Note that the shape of the outer peripheral surface is not limited to this and may be changed as appropriate, and the number and arrangement of the entrance windows W1 and exit windows W2 may also be changed as appropriate.

Furthermore, as shown in FIG. 5, the chamber body 11 has laser optical paths X formed therein that penetrate the inner peripheral surface 111 and the outer peripheral surface 112. Here, multiple laser optical paths X are formed for one side of the outer peripheral surface 112, and these multiple laser optical paths X extend to the opposing side. In other words, multiple laser optical paths X are formed for a pair of opposing sides of the outer peripheral surface 112, and here, eight laser optical paths X are formed for each pair of sides, for a total of 32 laser optical paths X. Note that the number of paths for each pair of sides and the total number may be changed as appropriate.

All of these laser optical paths X are formed on the same plane. Specifically, each laser optical path X is formed along a plane perpendicular to the central axis O of the internal space S, in other words, along the substrate contained in the internal space S.

As shown in Figures 3 and 4, the upper cover member 12 constitutes the upper wall of the chamber 10 and is, for example, a circular flat plate in which the above-mentioned multiple supply ports P1 are formed. The multiple supply ports P1 are, for example, arranged in a row when viewed from above, and five supply ports P1 are arranged here. However, the number and arrangement of the supply ports P1 may be changed as appropriate.

As shown in Figures 3 and 4, the porous member 13 is disposed below the upper cover member 12 with a gap therebetween. This divides the internal space S into an upper space S1 above the porous member 13 and a lower space S2 below the porous member 13. This porous member 13 is also called a shower head, in which numerous small holes h1 are formed through it in the thickness direction, and the material gas supplied from the supply port P1 to the upper space S1 is dispersed into the numerous small holes h1 and spreads throughout the entire lower space S2.

As shown in Figures 3 and 4, the lower cover member 14 has multiple through holes h2 that guide the material gas supplied to the internal space S to the exhaust port P2, and is also used here as a substrate holding member on which a substrate (not shown) is placed. This lower cover member 14 is, for example, a circular flat plate, and has multiple heaters H, such as cartridge heaters, provided on its underside.

Here, as shown in FIG. 6, the porous member 13 in this embodiment has a partition member 15 that is provided below the upper cover member 12 and separates the multiple supply ports P1.

The partition member 15 is interposed between the upper cover member 12 and the porous member 13 to spatially separate the multiple supply ports P1, and is, for example, a flat plate-like member that abuts against the upper cover member 12 and the porous member 13. Here, the partition member 15 is formed integrally with the porous member 13, but it may be provided integrally with the upper cover member 12, or may be a separate member from the porous member 13 and the upper cover member 12.

The partition members 15 spatially separate the multiple supply ports P1, thereby dividing the upper space S1 into multiple rooms a. The partition members 15 here divide the upper space S1 into a circular room a1 located at the center of the upper space S1, and at least one annular room a2 surrounding the circular room a1. More specifically, multiple ring-shaped partition members 15 are provided here, and these partition members 15 are positioned concentrically and arranged so that the central axis O passes through the center of each partition member 15.

With this configuration, the material gas supplied from each supply port P1 is supplied to only one of the chambers a in the upper space S1, and the material gas supplied from each supply port P1 is guided to the lower space S2 without mixing in the upper space S1. In this embodiment, one supply port P1 is provided corresponding to the circular chamber a1, and multiple (two) supply ports P1 are provided corresponding to the annular chamber a2.

By means of this partition member 15, multiple supply areas α corresponding to multiple rooms a are set within the chamber 10. To explain in more detail, each supply area α is an area set in the lower space S2 of the chamber 10, and is an area located below each room a of the upper space S1 separated by the partition member 15. In other words, the material gas supplied from each supply port P1 is configured to be supplied mainly to one supply area α, and the supply area α here consists of a circular central area α1 set in the center of the chamber, similar to the room a of the upper space S1, and at least one or more annular areas α2, α3 surrounding the central area α1.

In the above-described configuration, the material gas introduced into the lower space S2 flows into the through hole h2 provided on the outer periphery of the lower cover member 14, so that the central area α1 is located upstream of the flow of this material gas, and the annular areas α2 and α3 are located downstream.

In this configuration in which multiple supply areas α are set in the chamber 10, as shown in FIG. 1, a material gas supply system GS is provided to independently supply material gas to each supply area α. This material gas supply system GS has the above-mentioned material gas supply path L1, first fluid control device MFC1, dilution gas supply path L3, and second fluid control device MFC2, and is provided corresponding to each of the multiple supply areas α. In more detail, the material gas supply system GS corresponding to a certain supply area α is mainly composed of a material gas supply path L1 connected to one or more supply ports P1 that supply material gas to the supply area α, a first fluid control device MFC1 provided in the material gas supply path L1, a dilution gas supply path L3 connected to the material gas supply path L1, and a second fluid control device MFC2 provided in the dilution gas supply path L3.

Next, we will explain the laser emission mechanism 20, the laser detection mechanism 30, and the control device 40.

As shown in FIG. 2, the laser emission mechanism 20 emits laser light from multiple locations around the chamber 10 toward an entrance window W1 formed in the peripheral wall of the chamber 10. Specifically, the laser emission mechanism 20 has a laser light source 21, such as a semiconductor laser, and a fiber splitter 22 that splits the laser light emitted from the laser light source 21 into multiple fibers, and the emission ends 23 of each fiber are arranged to surround the internal space S. Here, the outer peripheral surface 112 of the chamber 10 is polygonal, and multiple fibers are provided for each of the multiple sides (specifically, four sides) of the outer peripheral surface 112. As a result, the laser light emitted from the laser light source 21 is emitted toward the internal space S from all four sides.

As shown in FIG. 2, the laser detection mechanism 30 detects each laser light emitted from multiple locations, passing through the chamber 10, and emitting from an emission window W2 formed in the peripheral wall of the chamber 10. Specifically, the laser detection mechanism 30 has multiple laser detectors 31 that detect the laser light emitted from each fiber and passing through the internal space S, and each laser detector 31 is arranged opposite the emission end 23 of the fiber so as to sandwich the internal space S. The light intensity signal indicating the intensity of the laser light detected by these laser detectors 31 is output to the above-mentioned control device 40 via an amplifier A or the like.

The control device 40 controls the above-mentioned material gas supply system GS to control the two-dimensional concentration distribution of the material gas supplied into the chamber 10 to a predetermined target concentration distribution.

More specifically, the control device 40 is physically a dedicated or general-purpose computer equipped with a CPU, internal memory, input/output means, an AD converter, etc., and is configured to perform functions such as a target concentration distribution receiving unit 41, a two-dimensional concentration calculation unit 42, a flow rate adjustment unit 43, and a concentration adjustment unit 44, as shown in FIG. 7, by the CPU and other components working together based on the concentration control program stored in the internal memory.

The target concentration distribution receiving unit 41 receives target concentration distribution data indicating a target concentration distribution previously determined by a user in accordance with a recipe for substrate processing such as etching. The target concentration distribution data may be input to the control device 40 via an input means, for example, or may be transmitted to the control device 40 by wire or wirelessly. As shown in FIG. 8, the concentration distribution data may be data indicating the correlation between the radial distance R from the center of the chamber 10 and the target concentration at that distance. Details of this target concentration distribution will be described later.

The two-dimensional concentration calculation unit 42 acquires the light intensity signal detected by the laser detection mechanism 30, and calculates the two-dimensional concentration distribution in the chamber 10 based on this light intensity signal. The two-dimensional concentration distribution here refers to the concentration distribution in a plane along the laser light in the chamber 10, or in other words, the concentration distribution along the substrate contained in the chamber 10.

More specifically, the two-dimensional concentration calculation unit 42 is configured to calculate the two-dimensional concentration distribution of an area defined by two mutually perpendicular axes by performing arithmetic processing on the light intensity signals detected by each laser detector 31 based on a predetermined algorithm for calculating the two-dimensional concentration distribution, and calculates the two-dimensional concentration distribution of at least the multiple supply areas α described above.

The flow rate adjustment unit 43 controls the material gas flow rate for each supply area α based on the target concentration distribution data received by the target concentration distribution reception unit 41, and specifically controls the material gas supply system GS described above.

More specifically, the flow rate adjustment unit 43 determines the target flow rates of the multiple first fluid control devices MFC1 and the multiple second fluid control devices MFC2 based on the target concentration distribution data, and inputs and sets the target flow rates to the first fluid control devices MFC1 and the second fluid control devices MFC2.

The concentration adjustment unit 44 controls the above-mentioned material gas supply system GS based on the target concentration distribution data received by the target concentration distribution receiving unit 41 and the two-dimensional concentration distribution calculated by the two-dimensional concentration calculation unit 42.

More specifically, the concentration adjustment unit 44 compares the concentration of each supply area α in the target concentration distribution data with the concentration of each supply area α in the two-dimensional concentration distribution, and feedback controls the target flow rate of the first fluid control device MFC1 or the second fluid control device MFC2 corresponding to each supply area α. Note that the first fluid control device MFC1 or the second fluid control device MFC2 corresponding to each supply area α here refers to the first fluid control device MFC1 on the material gas supply path L1 connected to the supply port P1 corresponding to each supply area α (i.e., the supply port P1 that mainly supplies material gas to each supply area α), and the second fluid control device MFC2 on the dilution gas supply path L3 connected to this material gas supply path L1.

Next, the target density distribution will be described in detail.
As shown in Figure 8, the target concentration distribution in this embodiment has a peak Rp (i.e., the maximum concentration) in a certain supply area α (hereinafter referred to as the one supply area α) among the supply areas α described above; in other words, it is a concentration distribution that is set so that the target concentration in the one supply area α is higher than the target concentrations in the other supply areas α.

In this embodiment, the concentration distribution shown in FIG. 8 will be taken up and described as a more specific example of the target concentration distribution. That is, as described above, the multiple supply areas α are composed of a central area α1 (hereinafter referred to as the first area α1), an annular area α2 (hereinafter referred to as the second area α2) surrounding the first area α1, and an annular area α3 (hereinafter referred to as the third area α3) surrounding the second area α2, and the target concentration distribution will be described as having a peak Rp in the second area α2.

Thus, the control device 40 of this embodiment is configured to control the material gas supply system GS to adjust the material gas flow rate for each supply area, and then control the material gas supply system GS to adjust the material gas concentration for each supply area.

The specific concentration control operation of the control device 40 will be explained below with reference to the flowchart in Figure 9.

First, when the target concentration distribution receiving unit 41 receives the target concentration distribution data, the control device 40 takes an initial control mode for setting the initial values of the material gas flow rate and material gas concentration for each supply area.

Specifically, in this initial control mode, the control device 40 controls the material gas supply system GS so that the material gas flow rates for each supply area are set to predetermined initial flow rates and the material gas concentrations for each supply area are set to predetermined initial concentrations based on the target concentration distribution data (M1).

In this embodiment, the initial flow rates of the respective supply areas α1 to α3 are set to be equal to each other.
That is, the control device 40 of this embodiment controls the material gas supply system GS so that Q1 = Q2 = Q3 = Qs, where Q1 is the material gas flow rate to the first area α1, Q2 is the material gas flow rate to the second area α2, Q3 is the material gas flow rate to the third area α3, and Qs is a preset initial flow rate.

On the other hand, the initial concentration of each of the supply areas α1 to α3 is set based on the target concentration distribution data. Specifically, the initial concentration of the supply area α2 having the peak of the target concentration distribution is the average concentration of the supply area α2 in the target concentration distribution, and the initial concentrations of the other supply areas α1 and α3 are zero.
That is, the control device 40 of this embodiment controls the material gas supply system GS so that C1=C3=0 and C2= _C2t , where C1 is the material gas concentration in the first area α1, C2 is the material gas concentration in the second area α2, and C3 is the material gas concentration in the third area α3. Also, _C2t is the average concentration in the second area α2 in the target concentration distribution.

Thus, in the initial control mode, the control device 40 sets the target flow rates for the first fluid control device MFC1 and the second fluid control device MFC2 so that Q1=Q2=Q3=Qs, C1=C3=0, and C2= _C2t (M1).
It should be noted that Q1, Q2, and Q3 do not necessarily have to be set to the same initial flow rate Qs, and may be set to different initial flow rates. Furthermore, C1 and C3 do not necessarily have to be zero, and C1 and C3 do not necessarily have to be equal, so long as they are at least lower than _C2t . Furthermore, _C2t is not limited to the average concentration of the second area α2 in the target concentration distribution, and may be, for example, the maximum concentration of the second area α2 in the target concentration distribution.

Next, the flow rate adjusting unit 43 controls the process gas supply system GS to adjust the process gas flow rate for each supply area (M2, M2').
Specifically, the flow rate adjusting unit 43 controls the material gas supply system GS so that the actual peak position Rp _meas , which is the peak position of the two-dimensional concentration distribution calculated by the two-dimensional concentration calculating unit 42, approaches the target peak position Rp _t , which is the peak position of the target concentration distribution. Note that each peak position Rp _meas , Rp _t here is the radial distance from the central axis O of the internal space S to each peak.

More specifically, the flow rate adjustment unit 43 is configured to control the material gas flow rate of the supply area adjacent to the second area α2 where the peak of the target concentration distribution is located, and specifically controls the material gas flow rate of the first area α1 which is set inside the second area α2, i.e., upstream of the material gas. This causes the peak of the two-dimensional concentration distribution calculated by the two-dimensional concentration calculation unit 42 to move within the second area α2.

Therefore, the flow rate adjustment unit 43 of this embodiment sets target flow rates for the first fluid control device MFC1 and the second fluid control device MFC2 _provided corresponding to the first area α1 so that the actual peak position Rp _meas approaches the target peak position Rp t. Note that, in the above-mentioned initial control mode, since the initial concentration in the first area α1 is set to zero, the flow rate adjustment unit 43 here changes the target flow rate of the second fluid control device MFC2 while keeping the target flow rate of the first fluid control device MFC1 at zero.

In this manner, by adjusting the material gas flow rate of the first area α1, if the difference between the actual peak position Rp _meas and the target peak position Rp _t falls below a predetermined distance, the adjusted material gas flow rate is determined (fixed) as the material gas flow rates Q1, Q2, and Q3 for each supply area (M3).

On the other hand, if the difference between the actual peak position Rp _meas and the target peak position Rp _t does not fall below a predetermined distance by simply adjusting the material gas flow rate Q1 in the first area α1, the flow rate adjuster 43 may adjust the material gas flow rate Q2 in the second area α2 or the material gas flow rate Q3 in the third area α3 so that the actual peak position Rp _meas approaches the target peak position Rp _t (M2').

Next, the concentration adjusting unit 44 controls the process gas supply system GS to adjust the process gas concentration for each supply area.
Specifically, the concentration adjusting unit 44 controls the material gas supply system GS so that the material gas concentration in each supply area approaches the average concentration in each supply area in the target concentration distribution without changing the material gas flow rate in each supply area (M4). This makes it possible to change the concentration values of the peaks and tails of the two-dimensional concentration distribution calculated by the two-dimensional concentration calculating unit 42.

Therefore, the concentration adjustment unit 44 of this embodiment sets target flow rates for the first fluid control device MFC1 and the second fluid control device MFC2 so that C1= _C1t , C2= _C2t , and C3= _C3t , without changing the material gas flow rates Q1, Q2, and Q3 for each supply area adjusted by the flow rate adjustment unit 43. Note that _C1t , _C2t , and _C3t are the average concentrations for each supply area α1 to α3 in the target concentration distribution.

Thereafter, the concentration adjustment unit 44 performs, for example, PID control of the target flow rates set in the first fluid control device MFC1 and the second fluid control device MFC2 corresponding to the first area α1 so that the first calculated concentration C1 _meas , which is the material gas concentration in the first area α1 calculated by the two-dimensional concentration calculation unit 42, approaches the first target concentration C1 _t , which is the average concentration in the first area α1 in the target concentration distribution (M5). Note that the first calculated concentration C1 _meas here is the average concentration in the first area α1 (calculated average concentration), but may be, for example, a representative concentration at a certain point in the first area α1.

The concentration adjustment unit 44 performs, for example, PID control of the target flow rates set in the first fluid control device MFC1 and the second fluid control device MFC2 corresponding to the second area α2 so that the second calculated concentration C2 _meas , which is the material gas concentration in the second area α2 calculated by the two-dimensional concentration calculation unit 42, approaches the second target concentration C2 _t , which is the average concentration in the second area α2 in the target concentration distribution (M6). Note that the second calculated concentration C2 _meas here is the average concentration (calculated average concentration) in the second area α2, but may be, for example, a representative concentration at a certain point in the second area α1.

Furthermore, the concentration adjustment unit 44 performs, for example, PID control of the target flow rates set in the first fluid control device MFC1 and the second fluid control device MFC2 corresponding to the third area α3 so that the third calculated concentration _C3meas , which is the material gas concentration in the third area α3 calculated by the two-dimensional concentration calculation unit 42, approaches the third target concentration _C3t , which is the average concentration in the third area α3 in the target concentration distribution (M7). Note that the third calculated concentration _C3meas here is the average concentration (calculated average concentration) in the third area α3, but may be, for example, a representative concentration at a certain point in the third area α1.

Thereafter, the control device 40 compares the difference E, such as the square root error, between each of the average concentrations C1 _meas to C3 _meas of each supply area α calculated by the two-dimensional concentration calculation unit 42 and each of the average concentrations C1 _t to C3 _t of each supply area α in the target concentration distribution with a predetermined threshold value E _th , and determines whether the difference between the difference E and the threshold value E _th falls below a predetermined value ε (M8).

Then, if the difference between the difference E and the threshold value _Eth is below the predetermined value ε at (M8), the control device 40 ends the concentration control operation, and if the difference between the difference E and the threshold value _Eth is not below the predetermined value ε at (M8), the control device 40 repeats the operations from (M5) to (M7).

According to the concentration control system 100 configured in this manner, the control device 40 first adjusts the material gas flow rates Q1 to Q3 for each supply area, thereby enabling the actual peak position Rp _meas of the two-dimensional concentration distribution to move to the target peak position Rp _t or to its vicinity, and then, by adjusting the material gas concentrations C1 to C3 for each supply area while keeping the material gas flow rates Q1 to Q3 fixed, it is possible to change the concentration values of the actual peak position Rp _meas and the tail of the two-dimensional concentration distribution without moving the position of the actual peak position Rp _meas or while keeping the movement to a negligible extent.
This makes it possible to control the two-dimensional concentration distribution of the material gas supplied to the chamber 10 to a desired target concentration distribution, which is useful for substrate processing such as etching.

In addition, since the supply area α is composed of the first area α1, which is a central area, and the second area α2 and the third area α3, which are annular areas, the material gas concentration can be controlled at both the center and the outer periphery of the internal space S, and the peaks of the two-dimensional concentration distribution can be located at various positions in the radial direction, such as the center or outer periphery of the chamber 10, making it easier to control the two-dimensional concentration distribution to a more desired target concentration distribution.

The present invention is not limited to the above embodiment.

For example, as shown in FIG. 10, the supply area α in the above embodiment, which is the central area α1 and the annular areas α2 and α3, may be divided in the circumferential direction of the chamber 10 into a plurality of divided areas α11-α1N, α21-α2N, and α31-α3N, and a material gas supply system GS may be provided corresponding to each of these plurality of divided areas. Note that N is the number of divisions in the circumferential direction.

In such a configuration, the control device 40 may control the material gas supply system GS after (M8) in the concentration control operation of the above embodiment to adjust the material gas concentration for each divided area, thereby controlling the two-dimensional concentration distribution to the target concentration distribution.

For a more specific explanation, the density control of the first divided area α21 to the Nth divided area α2N obtained by dividing the second area α2 into a plurality of areas will be taken up and described in detail.
First, as shown in FIG. 11, the concentration control unit 44 performs, for example, PID control on the target flow rates set in the first fluid control device MFC1 and the second fluid control device MFC2 corresponding to the first divided area α21 so that the first divided calculated concentration C21 _meas , which is the material gas concentration of the first divided area α21 calculated by the two-dimensional concentration calculation unit 42, matches the first divided target concentration C21 _t , which is the average concentration of the first divided area α21 in the target concentration distribution (K1).

Then, the concentration control unit 44 performs the same concentration control for the second divided area α22 to the Nth divided area α28 as for the first divided area α21 (K2) to (KN).

Thereafter, the control device 40 compares the difference E2, such as the square root error, between the average concentrations C21 _meas to C2N _meas of each of the divided areas α21 to 2N calculated by the two-dimensional concentration calculation unit 42 and the average concentrations C21 _t to C2N _t of each of the divided areas α21 to 2N in the target concentration distribution with a predetermined threshold value E2 _th , and determines whether the difference between the difference E2 and the threshold value E2 _th falls below a predetermined value ε2 (KX).

Then, in the case where the difference between the difference E2 and the threshold value _E2th in (KX) is below the predetermined value ε2, the control device 40 ends the concentration control operation, and in the case where the difference between the difference E2 and the threshold value _E2th in (KX) is not below the predetermined value ε2, the control device 40 repeats the operations from (K1) to (KN).

The control device 40 may be configured to perform the same concentration control for the multiple divided areas α11 to α1N obtained by dividing the first area α1 and the multiple divided areas α31 to α3N obtained by dividing the third area α3 as for the multiple divided areas α21 to α2N obtained by dividing the second area α2.

In this way, by subdividing the central area and the annular area into multiple divided areas and controlling the density of these divided areas, it is possible to control the two-dimensional density distribution more finely than in the previous embodiment.

In addition, in the above embodiment, the square root error E between the average concentrations C1 _meas to C3 _meas of each supply area α and the average concentrations C1 _t to C3 _t of each supply area α in the target concentration distribution was used in the judgment (M8) of whether to terminate the concentration control operation. However, this is not necessarily limited to this, and the concentration control operation may be terminated, for example, when the differences |C1 _t -C1 _meas |, |C2 t -C2 meas |, and |C3 _t -C3 _meas | between the average concentrations C1 _meas to _{C3 meas} of each supply area α and the average concentrations C1 _t to _{C3 t} of each supply area α in the target concentration distribution are all equal to or less than a predetermined threshold value.

Furthermore, while the chamber 10 has a polygonal outer surface 112 in the above embodiment, the outer surface 112 may be modified as appropriate to have a triangular, rectangular, circular, elliptical, or other shape.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the invention.

REFERENCE SIGNS LIST 100 Concentration control system 10 Chamber GS Material gas supply system L1 Material gas supply path L2 Material gas exhaust path L3 Dilution gas supply path S Internal space P1 Supply port MFC1 First fluid control device MFC2 Second fluid control device 15 Partition member α Supply area 20 Laser emission mechanism 30 Laser detection mechanism 40 Control device 41 Target concentration distribution receiving unit 42 Two-dimensional concentration calculation unit 43 Flow rate adjustment unit 44 Concentration adjustment unit

Claims (11)

A concentration control system for controlling a two-dimensional concentration distribution of a material gas supplied into a chamber that accommodates a substrate to a predetermined target concentration distribution, comprising:
a source gas supply system provided corresponding to each of a plurality of supply areas set in the chamber;
a control device that controls the process gas supply system to change the two-dimensional concentration distribution to the target concentration distribution;
The control device is configured to control the material gas supply system to adjust the material gas flow rate for each supply area, and then control the material gas supply system to adjust the material gas concentration for each supply area. the target concentration distribution has a peak in one of the supply areas,
The concentration control system according to claim 1 , wherein the control device adjusts a flow rate of the material gas in another supply area adjacent to the one supply area to move a peak of the two-dimensional concentration distribution within the one supply area. The concentration control system according to claim 1 or 2, wherein the control device adjusts the material gas concentration for each supply area to control the calculated average concentration calculated in each supply area to approach the target average concentration for each supply area in the target concentration distribution. The concentration control system according to any one of claims 1 to 3, wherein the plurality of supply areas comprises a central area set in the center of the chamber and at least one annular area surrounding the central area. the central area and the annular area are composed of a plurality of divided areas divided in a circumferential direction of the chamber,
5. The concentration control system according to claim 4, wherein the process gas supply system is provided corresponding to each of the plurality of divided areas. The concentration control system of claim 5, wherein the control device controls the material gas supply system to adjust the material gas concentration for each divided area, thereby controlling the two-dimensional concentration distribution to approach the target concentration distribution. The chamber comprises:
a chamber body having an internal space to which the material gas is supplied;
A cover member that covers the internal space and has a plurality of supply ports formed therein corresponding to each of the supply areas;
The concentration control system according to claim 1 , further comprising: a partition member provided on the interior space side of the lid member to separate the plurality of supply ports. The gas supply system comprises:
a source gas supply passage connected to each of the supply areas;
a first fluid control device provided in each of the process gas supply paths;
a dilution gas supply line connected to each of the material gas supply lines;
The concentration control system according to claim 1 , further comprising: a second fluid control device provided in each of the dilution gas supply paths. a laser emission mechanism that emits laser light from a plurality of points around the chamber toward an entrance window formed in a peripheral wall of the chamber;
a laser detection mechanism that detects each laser light emitted from the plurality of locations, passing through the chamber, and exiting from an exit window formed in a peripheral wall of the chamber;
9. The concentration control system according to claim 1, further comprising: a two-dimensional concentration distribution calculation unit that acquires a light intensity signal of each of the laser lights detected by the laser detection mechanism and calculates a two-dimensional concentration distribution of the material gas in the chamber based on the light intensity signal. A program used in a concentration control system for controlling a two-dimensional concentration distribution of a material gas supplied into a chamber that accommodates a substrate to a predetermined target concentration distribution, comprising:
the concentration control system includes a source gas supply system provided corresponding to each of a plurality of supply areas set in the chamber, and a control device that controls the source gas supply system to control the two-dimensional concentration distribution to the target concentration distribution,
a concentration control program for causing the control device to control the material gas supply system to adjust the material gas flow rate for each of the supply areas, and then to control the material gas supply system to adjust the material gas concentration for each of the supply areas; A method for controlling a two-dimensional concentration distribution of a material gas supplied into a chamber that accommodates a substrate to a predetermined target concentration distribution, the method controlling the two-dimensional concentration distribution to the target concentration distribution by controlling a material gas supply system provided corresponding to each of a plurality of supply areas set in the chamber, the method comprising:
the process includes controlling the material gas supply system to adjust the material gas flow rate for each of the supply areas, and then controlling the material gas supply system to adjust the material gas concentration for each of the supply areas.