TW202234026A - Gas supply system for electrostatic chuck device, gas supply method and program for gas supply system - Google Patents

Abstract

A gas supply system for an electrostatic chuck device, wherein the gas supply system for an electrostatic chuck device includes: a plurality of gas supply pipelines supplying the thermal conductive gas to each of a plurality of regions set in the space; a common pipeline connected to each of the gas supply pipelines and introducing the thermal conductive gas into each of the gas supply pipelines; and a flow rate calculation part calculating a flow rate of the thermal conductive gas introduced from the common pipeline to each of the gas supply pipelines, wherein the flow rate calculation part calculates a flow rate of the thermal conductive gas introduced into each of the gas supply pipelines based on a flow rate characteristic of a first flow rate resistance element provided in each of the gas supply pipelines, a primary side pressure of the first flow rate resistance element, and a secondary side pressure of the first flow rate resistance element, wherein a pressure sensor measuring the primary side pressure is provided on the common pipeline.

Description

Gas supply system for electrostatic chuck device, gas supply method, and program for gas supply system

The present invention relates to a gas supply system for an electrostatic chuck device, a gas supply method, and a program for the gas supply system, which adsorb an object by electrostatic force.

Conventionally, in a semiconductor manufacturing process using a plasma processing apparatus such as a plasma etching apparatus and a plasma chemical vapor deposition (CVD) apparatus, an electrostatic chuck is used to fix a sample such as a silicon wafer in a vacuum chamber. device. The electrostatic chuck device includes a suction plate that attracts an object by electrostatic force, and a metal base plate that is in contact with the back surface of the suction plate. Using an electrostatic chuck device, the back side (surface to be adsorbed) of the silicon wafer is adsorbed by the adsorption plate, thereby fixing the silicon wafer, and, for example, the heat of the plasma applied to the silicon wafer is released to the base plate side for cooling, thereby enabling Homogenization of surface temperature distribution is achieved.

However, the suction surface of the suction plate or the suctioned surface of the silicon wafer has fine irregularities. Therefore, even in the state where the silicon wafer is adsorbed by the electrostatic chuck device, a tiny space with a thickness of about 10 μm is created between the adsorbed surface and the adsorbed surface, and the physical contact area becomes small, so the heat conduction efficiency decreases. Conventionally, a plurality of gas supply ports are provided on the adsorption surface of the adsorption plate, and thermally conductive gas is supplied to the space between the adsorption surface of the silicon wafer and the adsorption surface of the adsorption plate, thereby making the electricity applied to the silicon wafer. The heat of the slurry is efficiently released to the adsorption plate side (Patent Document 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2020-053576

[The problem to be solved by the invention]

In the semiconductor manufacturing process using the plasma processing apparatus, it is required to improve the uniformity of the surface temperature of objects such as wafers. The uniformity of the surface temperature of the wafer depends on the pressure of the thermally conductive gas (also referred to as the wafer backside pressure) in a plurality of regions between the suction surface and the suctioned surface, and the wafer backside pressure in each region depends on The flow rate of the thermally conductive gas supplied from the gas supply port corresponding to each area. Therefore, in order to improve the uniformity of the surface temperature distribution of the wafer, it is important to grasp the flow rate of the thermally conductive gas supplied to each region. On the other hand, in order to grasp the flow rate of the thermally conductive gas to be supplied to each region, the number of parts increases, and there is a problem that the manufacturing cost increases.

The present invention has been made to solve the above-mentioned problems at one stroke, and its main subject is to improve the uniformity of the surface temperature distribution of an object such as a wafer, and to reduce the number of parts to achieve a manufacturing cost in a gas supply system for an electrostatic chuck device. cuts. [Means of Solving Problems]

That is, the gas supply system for an electrostatic chuck device of the present invention supplies the thermally conductive gas to the space between the suction surface of the electrostatic chuck device that attracts the object by electrostatic force and the surface to which the object is attracted, the electrostatic chuck device The gas supply system is characterized by comprising: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; a gas supply line for introducing the thermally conductive gas; and a flow rate calculation unit for calculating the flow rate of the thermally conductive gas introduced into the respective gas supply lines from the common line, and the flow rate calculation unit is based on the The flow characteristics of the first flow resistance element of the gas supply line, the primary side pressure of the first flow resistance element, and the secondary side pressure of the first flow resistance element were calculated, and all the flows introduced into the gas supply lines were calculated. The flow rate of the thermally conductive gas, and a pressure sensor for measuring the primary side pressure is provided on the common line.

With such a configuration, the flow rate of the thermally conductive gas flowing in the gas supply line corresponding to each of the plurality of regions set in the space between the adsorption surface and the adsorbed surface can be grasped. Therefore, by controlling this The flow rate can control the pressure on the back surface of the wafer in each area, thereby improving the uniformity of the surface temperature distribution of objects such as wafers. Here, instead of providing pressure sensors individually on each gas supply line, pressure sensors are provided on a common line to achieve common use, so that the number of parts can be reduced and manufacturing costs can be reduced. The sensor measures the primary side pressure of the first flow resistance element required to calculate the flow rate of the thermally conductive gas flowing through each gas supply line.

In addition, the "first flow resistance element" can be any one as long as it has a flow rate characteristic in which the flow rate of the passing thermally conductive gas is determined by the pressure on the primary side and the pressure on the secondary side, as long as it is a laminar flow element resistance. Body is excellent.

As a specific form of the gas supply system for individually controlling the flow rate of the thermally conductive gas flowing in each gas supply line, a form in which the first gas supply line in each of the gas supply lines is configured may be mentioned. A fluid control valve is provided downstream of the resistance element, and the opening degree of the fluid control valve is feedback-controlled based on the flow rate calculated by the flow rate calculation unit.

Preferably, the gas supply system for the electrostatic chuck device is provided with a second flow resistance element downstream of the fluid control valve in each of the gas supply lines, and further includes a pressure calculation unit that calculates each of the gas supply lines. the pressure of the thermally conductive gas in the region, and the pressure calculation unit is based on the primary side pressure of the second flow resistance element, the flow rate of the thermally conductive gas passing through the second flow resistance element, and the The flow rate characteristic of the second flow resistance element is used to calculate the pressure of the thermally conductive gas in each of the regions. In this case, by utilizing the flow characteristics of the flow resistance element, that is, the primary side pressure (for example, the pressure in the gas supply line) and the secondary side pressure (for example, the wafer backside pressure) of the flow resistance element, and the passing heat conduction It is possible to calculate and grasp the wafer backside pressure in each region based on the inherent characteristics of the relationship between the flow rates of the gaseous gases.

In addition, the "second flow resistance element" may be any one as long as it is an element having a flow rate characteristic in which the flow rate of the passing thermally conductive gas is determined by the pressure on the primary side and the pressure on the secondary side, as long as it is a laminar flow element resistance. Body is excellent. The laminar flow element resistance body has excellent machining accuracy and excellent reproducibility can be obtained. Therefore, by using the laminar flow element resistance body as the flow resistance element, the thermal conductivity of the space between the adsorption surface and the adsorption surface can be calculated with higher accuracy. gas pressure. In addition, since the laminar flow element resistance body has a high degree of freedom in design, the degree of freedom in the outer diameter of the outlet of the thermally conductive gas can be increased, and the occurrence of arc discharge can be expected to be suppressed.

Preferably, in the gas supply system for the electrostatic chuck device, each of the gas supply lines includes a gas supply flow path opened on the adsorption surface, and in each of the gas supply lines, the second flow resistance element is provided at The gas is supplied into the flow path. In this way, since the flow resistance element is provided in the gas supply flow path opened on the suction surface of the suction plate, the pressure on the back surface of the wafer in each region can be calculated more accurately, and the surface temperature of the object such as the wafer can be raised further. uniformity of distribution.

A specific form of the pressure calculation unit includes a form in which the flow rate calculated by the flow rate calculation unit and the relational expression of the material balance representing the flow rate of the thermally conductive gas in the gas supply line are calculated to pass through the flow rate of the thermally conductive gas of the second flow resistance element.

In order to be able to diagnose whether there is any abnormality in the back surface of the wafer during plasma processing, such as a decrease in the attraction force to the wafer due to the deterioration of the device over time, or local warpage of the wafer, etc., it is preferable that the gas supply system further includes: A diagnosis unit that compares the calculated pressure of the thermally conductive gas with a predetermined reference pressure, and diagnoses an abnormality in the pressure value of the thermally conductive gas in each of the regions.

The gas supply system is preferably configured to adjust the flow rate of the thermally conductive gas introduced into the respective gas supply lines so that the pressure of the thermally conductive gas calculated by the pressure calculation unit becomes a value within a predetermined range .

In the gas supply system, it is preferable that the plurality of regions are regions set by dividing the space into radial shapes. With such a configuration, by monitoring the pressure or mass flow rate of the thermally conductive gas supplied from each gas supply line, the occurrence of local warpage along the circumferential direction of the wafer can be detected.

In the gas supply system, as a specific configuration for detecting the occurrence of warpage along the circumferential direction of the wafer, a configuration in which the diagnosis unit is configured based on the supply to each of the radially divided The mass flow rate of the thermally conductive gas in the region or the pressure of the thermally conductive gas in each of the radially divided regions is used to diagnose whether or not the object is warped.

Further, in the gas supply system, it is preferable that the plurality of regions are regions set by dividing the space into concentric circles and further dividing the annular region therein into radial shapes. With such a structure, the pressure on the back surface of the wafer can be controlled by controlling the flow rate of the thermally conductive gas flowing in the gas supply line corresponding to the inner region, and the uniformity of the surface temperature distribution of the object such as the wafer can be improved. . In addition, by monitoring the pressure of the thermally conductive gas supplied from the respective gas supply lines corresponding to the respective regions formed by further dividing the annular region formed on the outer side, local warpage along the circumferential direction of the wafer can be detected. occurrence of the song.

Moreover, as a specific form of the said gas supply system, the form in which the said thermally conductive gas is helium gas is mentioned.

The gas supply system for the electrostatic chuck device preferably further includes a second gas introduction line, the second gas introduction line is connected to the upstream of the first flow resistance element in each of the gas supply lines, and is directed to each of the gas supply lines. The gas supply line introduces a second gas different from the thermally conductive gas, and the flow rate calculation unit is based on the flow rate characteristic of the first flow resistance element, the primary side pressure of the first flow resistance element, and the first flow rate resistance element. The flow rate of the second gas introduced into each gas supply line is calculated from the secondary side pressure of the flow resistance element, and a pressure sensor for measuring the primary side pressure is provided on the second gas introduction line. In this way, since the second gas introduction line into which the second gas such as argon or nitrogen is introduced is provided separately from the common line in each gas supply line, the supply of the thermally conductive gas and the second gas can be switched in a short time. supply. In addition, since a pressure sensor that measures the primary side pressure of the flow resistance element required for calculating the flow rate of the second gas flowing in each gas supply line is provided in the second gas introduction line and shared, The number of parts can be reduced to reduce manufacturing costs.

In addition, the gas supply method of the present invention is a gas supply method for supplying a thermally conductive gas to a space between an attracting surface of an electrostatic chuck device that attracts an object by electrostatic force and a surface to which the object is attracted, the electrostatic chuck The apparatus includes: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; and a common line connected to the respective gas supply lines for introducing the respective gas supply lines into the respective gas supply lines The thermally conductive gas, and the gas supply method is based on the flow rate characteristic of the first flow resistance element provided on each of the gas supply lines, the primary side pressure of the first flow resistance element, and the first flow resistance element The pressure on the secondary side of pressure.

In addition, the program for a gas supply system of the present invention is a program for a gas supply system for supplying a thermally conductive gas to the space between the suction surface of the electrostatic chuck device that attracts the object by electrostatic force and the suction surface of the object, The electrostatic chuck device includes: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; and a common line connected to each gas supply line for supplying each of the gases The heat-conductive gas is introduced into a supply line, and the gas supply system program causes a computer to function as a flow rate calculation unit based on the flow rate characteristic of the first flow resistance element provided in each of the gas supply lines, The primary side pressure of the first flow resistance element and the secondary side pressure of the first flow resistance element are calculated to calculate the flow rate of the thermally conductive gas introduced into the respective gas supply lines from the common line, so The flow rate calculation unit uses, as the primary side pressure, a measurement value of a pressure sensor provided on the common line.

If it is such a gas supply method or a program for a gas supply system, the same functions and effects as those of the gas supply system of the present invention can be exhibited. [Effect of invention]

According to the present invention thus constituted, in the gas supply system for the electrostatic chuck device, the uniformity of the surface temperature distribution of the object such as the wafer can be improved, and the number of parts can be reduced, thereby reducing the manufacturing cost.

Hereinafter, an embodiment of an electrostatic chuck device including a gas supply system of the present invention will be described with reference to the drawings.

As shown in FIG. 1 , the electrostatic chuck device 100 of the present embodiment is used for electrostatically attracting, for example, a wafer W to be processed in a vacuum chamber C of a semiconductor manufacturing apparatus using plasma. Specifically, as shown in FIGS. 1 and 2 , the electrostatic chuck device 100 includes an electrostatic chuck unit 1 having a suction surface 111 for electrostatically attracting the wafer W, and a cooling unit 2 having a cooling surface 211 for cooling the electrostatic chuck unit 1 . , and a gas supply system 3 for supplying a thermally conductive gas to the space G between the suction surface 111 of the electrostatic chuck unit 1 and the suctioned surface S of the wafer W. In addition, the vacuum chamber C is configured to be evacuated by a vacuum pump not shown.

As shown in FIGS. 2 to 4 , the electrostatic chuck unit 1 includes a suction plate 11 formed of an insulator such as ceramics or glass and formed into a circular flat plate, an internal electrode 12 embedded in the suction plate 11 , and an internal electrode 12 to the internal electrode. 12 Power supply 13 for applying voltage. When a voltage is applied to the internal electrodes 12 by the power source 13, a dielectric polarization phenomenon occurs in the suction plate 11, and the upper surface 111 of the suction plate 11 becomes a substantially planar suction surface. The electrostatic chuck unit 1 of the present embodiment is of a bipolar type, but is not limited to this, and may be of a unipolar type. In addition, the upper surface 111 is embossed etc., for example, and the surface shape is uneven|corrugated.

As shown in FIGS. 3 and 4 , a plurality of gas supply ports 3 a for blowing out thermally conductive gas are formed on the adsorption surface 111 of the adsorption plate 11 . Each of the gas supply ports 3a is formed, for example, to be rotationally symmetric about the rotational axis of the adsorption plate 11 as the axis of symmetry. In the present embodiment, the plurality of gas supply ports 3 a are formed in a line (here, two lines) concentrically, and are formed at substantially equal intervals along the circumferential direction in each line.

As shown in FIG. 4 , on the suction surface 111 , three or more (here, six) suction regions D divided into a radial shape (pizza cut shape) are set. Furthermore, it is comprised so that the thermally conductive gas whose flow volume and pressure are adjusted individually for each area|region can be supplied to the space G from the gas supply port 3a provided in each adsorption area|region D.

Each gas supply port 3a is formed by a through hole 113 provided so as to penetrate the adsorption plate 11 in the plate thickness direction. The diameter dimension (inner diameter) of the through hole 113 is about several μm to several tens of μm (for example, 0.03 mm), and the length dimension (dimension along the axial direction) is about several mm (for example, 2 mm), but these sizes may be Appropriate changes.

As shown in FIGS. 2 and 3 , the cooling unit 2 includes a metal base plate 21 in the shape of a circular flat plate, a refrigerant flow path 212 formed in the base plate 21 , and a cooling medium for circulating the refrigerant in the refrigerant flow path 212 . Refrigerant circulation mechanisms such as coolers (not shown). The temperature of the entire base plate 21 is lowered by allowing the refrigerant to flow through the refrigerant flow path 212 by the refrigerant circulation mechanism, and the upper surface 211 of the base plate 21 becomes a substantially planar cooling surface. The suction plate 11 is placed on the base plate 21 so that the lower surface 112 (back surface) of the suction plate 11 is in surface contact with the cooling surface 211 of the base plate 21 . The refrigerant flow path 212 is formed in the inside of the base plate 21 along a direction parallel to the cooling surface 211 .

The gas supply system 3 supplies the thermally conductive gas to the space G. Specifically, as shown in FIG. 5 , the gas supply system 3 includes: a common line 31 through which the heat-conductive gas flows; a plurality of gas supply lines 32 connected to the common line 31 at the upstream end; A plurality of branched leakage lines 34; and a control device 33. The thermally conductive gas may be, for example, a single gas such as helium or argon, or an arbitrary gas such as a mixed gas in which a plurality of gases are mixed at an arbitrary ratio.

A gas supply source (not shown) is connected to the upstream side of the common line 31 , and a thermally conductive gas is introduced into each gas supply line 32 . The common line 31 is provided with a fluid control valve 40 and a first pressure sensor 41 for measuring the pressure of the heat-conductive gas introduced into each gas supply line 32 . That is, it can be said that the first pressure sensor is shared among the gas supply lines 32 . Furthermore, the first pressure sensor 41 is configured to be able to measure the pressure and temperature of the thermally conductive gas passing therethrough.

The fluid control valve 40 changes its valve opening according to the control signal from the control device 33, thereby changing the flow rate of the thermally conductive gas flowing in the common pipeline 31, such as piezoelectric actuator valves, electromagnetic actuator valves, Thermal actuator valves, etc.

Each gas supply line 32 (from the connection point _PJ with the common line 31 to the gas supply port 3a ) is provided corresponding to each adsorption area D set on the adsorption surface 111 . In this embodiment, the plurality of gas supply lines 32 are all connected to the common line 31 , and each gas supply line 32 is configured to supply the thermally conductive gas introduced from the common line 31 to the space G from the gas supply port 3 a of each adsorption region D. Specifically, each gas supply line 32 includes a through flow path 321 (“gas supply flow path” within the scope of the patent application) that penetrates through the adsorption plate 11 in the plate thickness direction at its downstream end. The through-flow passage 321 includes the through-hole 113, and the downstream end of the through-hole 113 communicates with the gas supply port 3a.

On each gas supply line 32 , a first flow resistance element 44 , a second pressure sensor 42 , a fluid control valve 46 , a third pressure sensor 43 , and a second flow resistance element 45 are provided in this order from upstream.

The first flow resistance element 44 serves as a resistance when the thermally conductive gas flows, and has inherent flow characteristics that determine the mass flow rate of the passing gas based on the primary side pressure, the secondary side pressure, and the temperature of the gas, and is, for example, a laminar flow element resistance body Wait.

The second pressure sensor 42 measures the pressure (secondary side pressure) of the thermally conductive gas on the downstream side of the first flow resistance element 44 . The second pressure sensor 42 is configured to be able to measure the pressure and temperature of the passing thermally conductive gas.

The fluid control valve 46 changes its valve opening according to the control signal from the control device 33, thereby changing the flow rate of the passing heat-conductive gas, such as piezoelectric actuator valve, electromagnetic actuator valve, thermal actuator valve Wait.

The third pressure sensor 43 measures the pressure of the thermally conductive gas on the downstream side of the fluid control valve 46 . The third pressure sensor 43 is configured to be able to measure the pressure and temperature of the passing thermally conductive gas.

The second flow resistance element 45 is provided in the through flow path 321 (more specifically, the portion passing through the adsorption plate 11 ) in the gas supply line 32 . The second flow resistance element 45 serves as a resistance when the thermally conductive gas flows, and has an inherent flow characteristic that determines the mass flow rate of the passing gas based on the primary side pressure, the secondary side pressure, and the temperature of the gas. Here, it is based on the pressure of the thermally conductive gas in the gas supply line 32 (primary side pressure), the pressure of the thermally conductive gas in the space G (secondary side pressure. The temperature of the thermally conductive gas determines the flow rate of the thermally conductive gas passing through the second flow resistance element 45 .

The second flow resistance element 45 of the present embodiment is a laminar flow element resistance body, and as shown in FIG. 3 , includes a flow path forming member 5 having a flow path (resistance flow path) 51 serving as a resistance. The flow path forming member 5 has, for example, a cylindrical shape, and its diameter (outer diameter) and length (dimension along the axial direction) are substantially the same as those of the through hole 113 of the adsorption plate 11 . Each of the flow path forming members 5 is fitted into each of the through holes 113 of the suction plate 11 without a gap with a fitting tolerance. The flow-path forming member 5 may contain, for example, any insulating material such as ceramics. The second flow resistance element 45 is preferably provided so that the downstream end surface and the adsorption surface 111 of the adsorption plate 11 are coplanar. In the present embodiment, the second flow resistance element 45 is provided in all of the plurality of through holes 113 formed in the adsorption plate 11 . Furthermore, the first flow resistance element 44 is also constructed in the same manner.

Each leakage line 34 branches from downstream (more specifically, further downstream than the third pressure sensor 43 ) of the fluid control valve 46 in the gas supply line 32 . Each leakage line 34 is configured to be evacuated by a vacuum pump 344 via the third flow resistance element 342 . The third flow resistance element 342 serves as a resistance when the thermally conductive gas flows, and has an inherent flow characteristic that determines the mass flow rate of the passing gas based on the primary side pressure, the secondary side pressure, and the temperature of the gas, and is, for example, a laminar flow element resistance. body etc. In addition, each leakage line 34 is provided with a bypass line 341 which branches on the upstream side of the third flow resistance element 342 and merges on the downstream side of the third flow resistance element 342 . The bypass line 341 is provided with an on-off valve 343 that is switched on and off according to a control signal from the control device 33 . The on-off valve 343 is, for example, an air valve, a piezoelectric actuator valve, an electromagnetic actuator valve, a thermal actuator valve, or the like.

The control device 33 is a general-purpose or special-purpose computer with a built-in central processing unit (CPU), an internal memory, or the like. The control device 33 cooperates with the CPU and its peripheral devices based on a predetermined program stored in the internal memory, and as shown in FIG. , the functions of the flow rate target setting unit 335 and the valve control unit 336 .

The flow rate calculation unit 331 individually calculates the flow rate of the thermally conductive gas introduced into each gas supply line 32 from the common line 31 .

Specifically, the flow rate calculation unit 331 is configured based on the inherent flow rate characteristic of the first flow resistance element 44 , the primary side pressure P ₁ of the first flow resistance element 44 , and the secondary side of the first flow resistance element 44 . The pressure P ₂ is used to calculate the mass flow rate Q _in of the thermally conductive gas introduced into each gas supply line 32 from the common line 31 . This mass flow rate _Qin is the mass flow rate of the thermally conductive gas passing through the first flow resistance element 44 provided in each gas supply line 32 . More specifically, the flow rate calculation unit 331 calculates the mass flow rate _Qin based on the following equation (1) representing the relationship between the intrinsic flow rate characteristic of each first flow resistance element 44 and the primary side pressure and the secondary side pressure.

···（1） [Number 1]

···(1)

In Equation (1), f _res1 : a function representing the flow rate characteristic of the first flow resistance element 44 , P ₁ : pressure applied to the primary side (upstream side) of the first flow resistance element 44 , P ₂ : applied to the first flow resistance element 44 The pressure on the secondary side (downstream side) of the first flow resistance element 44, T _in : the temperature of the thermally conductive gas passing through the first flow resistance element 44 (here, it is regarded as the thermal conductivity passing through the second pressure sensor 42 ) the temperature of the gas is equal).

The flow rate calculation unit 331 is configured to acquire the primary side pressure P ₁ from the first pressure sensor 41 , acquire the secondary side pressure P ₂ and the temperature T _in of the thermally conductive gas from the second pressure sensor 42 , and obtain from the memory unit 333 . The flow rate characteristic function f _res1 is obtained, and the mass flow rate Q _in is calculated based on the information and Equation (1). The flow rate characteristic function f _res1 previously stored in the memory unit 333 is, for example, a map or the like represented by a function that combines the primary side pressure P ₁ applied to the first flow resistance element 44 and the pressure P 1 applied to the first flow resistance element 44 . The secondary side pressure P ₂ and the temperature T _in of the thermally conductive gas passing through the first flow resistance element 44 are used as input variables, and the mass flow rate passing through the first flow resistance element 44 is used as an output variable.

Moreover, the flow rate calculation part 331 of this embodiment is comprised so that the mass flow rate of the thermally conductive gas discharged|emitted from each leak line 34 may be calculated.

Specifically, the flow rate calculation unit 331 is configured based on the inherent flow characteristics of the third flow resistance element 342 , the primary pressure P ₃ of the third flow resistance element 342 , and the secondary pressure P of the third flow resistance element 342 . _VAC , the mass flow rate Q _VAC of the thermally conductive gas discharged from each leak line 34 is calculated separately. This mass flow rate Q _VAC is the mass flow rate of the thermally conductive gas passing through the third flow resistance element 342 provided on each leakage line 34 . More specifically, the flow rate calculation unit 331 calculates the mass flow rate Q _VAC based on the following equation (2) representing the relationship between the inherent flow rate characteristic of the third flow resistance element 342 and the primary side pressure and the secondary side pressure.

···（2） [Number 2]

···(2)

In Equation (2), f _res3 : a function representing the flow rate characteristic of the third flow resistance element 342 , P ₃ : pressure applied to the primary side (upstream side) of the third flow resistance element 342 , P _VAC : applied to the third flow resistance element 342 Pressure on the secondary side (downstream side) of the three flow resistance element 342 , T _VAC : temperature of the thermally conductive gas passing through the third flow resistance element 342 . In addition, the value of the secondary side pressure P _VAC may be a value measured by a pressure gauge (not shown) provided downstream of the third flow resistance element 342 in the leakage line 34, or may be preset and stored. Arbitrary value (eg, 0 Pa) in the memory section 333 . In addition, the value of the temperature T _VAC may be measured by the thermometer 344 provided on the leakage line 34 , or may be regarded as equal to the temperature of the thermally conductive gas passing through the third pressure sensor 43 .

The flow rate calculation unit 331 is configured to acquire the primary side pressure P ₃ and the temperature T _VAC of the thermally conductive gas from the third pressure sensor 43 , acquire the flow rate characteristic function f _res3 and the secondary side pressure P _VAC from the memory unit 333 , and based on the From these information and equation (2), the mass flow rate Q _VAC is calculated. The flow rate characteristic function f _res3 stored in the memory 333 in advance is, for example, a map or the like represented by a function that applies the pressure P ₃ applied to the primary side of the third flow resistance element 342 to the third flow resistance element 342 The secondary side pressure P _VAC and the temperature T _VAC of the thermally conductive gas passing through the third flow resistance element 342 are used as input variables, and the mass flow through the third flow resistance element 342 is used as an output variable.

The pressure calculation unit 332 separately calculates the pressure of the thermally conductive gas in each of the plurality of regions set so as to radially divide the space G between the adsorption surface 111 and the adsorbed surface S (that is, each adsorption region Wafer backside pressure in D).

Specifically, the pressure calculation unit 332 is configured based on the mass flow rate Q _ESC of the thermally conductive gas supplied from the gas supply port 3 a , the primary side pressure P ₃ of the second flow resistance element 45 , and the value of the second flow resistance element 45 . Based on the inherent flow characteristics, the wafer backside pressure P _wafer in each region is calculated. In addition, the mass flow rate _QESC is the mass flow rate of the thermally conductive gas passing through the through-flow passage 321 of the gas supply line 32, and in the present embodiment in which the second flow resistance element 45 is provided in the through-flow passage 321, it passes through the second flow resistance element 45. The mass flow rate of the thermally conductive gas in the flow resistance element 45 .

More specifically, the pressure calculation unit 332 is configured so as to be based on a material balance (that is, the amount of the thermally conductive gas entering the gas supply line 32 and the amount of the self-gas The thermally conductive gas supplied from the gas supply port 3a is calculated from the following equation (3) and the mass flow Q _in of the thermally conductive gas introduced into the gas supply line 32 The mass flow Q _ESC . Further, the pressure calculation unit 332 is configured to calculate the wafer backside pressure based on the following equation (4) representing the relationship between the calculated mass flow rate _QESC of the thermally conductive gas and the inherent flow rate characteristic of the second flow resistance element 45 . P _wafer .

···（3） [Number 3]

(3)

In the formula (3), Q _in : the mass flow rate of the thermally conductive gas introduced into the gas supply line 32 , Q _VAC : the mass flow rate of the thermally conductive gas discharged from the leak line 34 , (V/Z·R _u ·T _gas ) (dP/dt): the mass flow rate Q _LEAK of the thermally conductive gas leaking into the chamber from between the suction plate 11 and the wafer W, V: the distance between the fluid control valve 46 and the second flow resistance element 45 in the gas supply line 32 The volume of the flow path between the two, Z: the compressibility coefficient of the gas (here, Z=1), R _u : the gas constant (8.3145 J·mol ^-1 ·K ^-1 ), T _gas : the self-fluid in the gas supply line 32 Average temperature of the thermally conductive gas in the flow path from the control valve 46 to the second flow resistance element 45, dP/dt: The thermally conductive gas in the flow path from the fluid control valve 46 to the second flow resistance element 45 in the gas supply line 32 time variation of pressure. Furthermore, considering that the surface properties (such as shape, roughness, etc.) of the adsorption surface 111 of the adsorption plate 11 are not uniform within the surface, and the heat energy exchange during the process is unstable, the supply of the thermally conductive gas is started from the gas supply line 32. After a sufficient time has elapsed, the mass flow rate Q _LEAK is not in a steady state (steady state), and dP/dt may not be 0.

Here, the pressure calculation unit 332 is configured to acquire the mass flow rate Q _in and the mass flow rate Q _VAC from the flow rate calculation unit 331 , acquire the average temperature T _gas from the third pressure sensor 43 provided on the gas supply line 32 , and store the The unit 333 acquires the volume V, compressibility Z, and gas constant R _u of the flow path, and calculates the mass flow rate Q _ESC of the thermally conductive gas supplied from the gas supply port 3 a based on the information and equation (3).

···（4） [Number 4]

(4)

In equation (4), f _res2 : a function representing the flow rate characteristic of the second flow resistance element 45 , P ₃ : pressure applied to the primary side (upstream side) of the second flow resistance element 45 , P _wafer : wafer back surface Pressure (pressure applied to the secondary side of the second flow resistance element 45 ), T _ESC : temperature of the thermally conductive gas passing through the second flow resistance element 45 (here, considered to be equal to the temperature of the adsorption plate 11 ).

The pressure calculation unit 332 is configured to acquire the primary side pressure P ₃ from the third pressure sensor 43 , acquire the temperature T _ESC of the thermally conductive gas from the fiber-optic thermometer 47 measuring the temperature of the adsorption plate 11 , and acquire the flow rate characteristic from the memory unit 333 . The function f _res2 is used to calculate the wafer back pressure P _wafer based on the information and equation (4). The flow rate characteristic function f _res2 stored in advance in the memory 333 is, for example, a map or the like represented by a function that applies the pressure P ₃ applied to the primary side of the second flow resistance element 45 to the second flow resistance The pressure P _wafer on the secondary side of the element 45 and the temperature T _ESC of the thermally conductive gas passing through the second flow resistance element 45 are set as input variables, and the mass flow rate passing through the second flow resistance element 45 is set as an output variable.

The diagnosis unit 334 diagnoses whether or not there is an abnormality in the suction-receiving surface S of the wafer W. Specifically, the diagnosis unit 334 is configured to compare the wafer backside pressure P _wafer in each suction area D calculated by the pressure calculation unit 332 with a predetermined pressure P _s stored in the memory unit 333 in advance to diagnose the wafer Is there any abnormality in the adsorbed surface S of W? For example, when the absolute value of the difference between the wafer back pressure P _wafer and the pressure P _s in each suction area D is greater than or equal to a predetermined value, it is diagnosed that the suction-receiving surface S of the wafer W is abnormal. Diagnosed as normal. In addition, this pressure P _s is set suitably according to the content of the vacuum process with respect to the wafer W. As shown in FIG.

The diagnosis unit 334 may be configured to diagnose the presence or absence of local warpage along the circumferential direction as an abnormality on the suction-receiving surface S of the wafer W. As shown in FIG. Specifically, the diagnosis unit 334 may be configured to be configured to be based on the wafer back surface pressure P _wafer of each suction region D in a state where the thermally conductive gas is supplied to the radially divided suction regions D at a constant mass flow rate Q _ESC distribution, and diagnose whether the wafer W has warpage. For example, by comparing the wafer back surface pressure P _wafer in each suction region D with a predetermined pressure reference value stored in the memory unit 333 in advance, it can be determined whether or not local warpage occurs on the wafer W.

In addition, the diagnosis unit 334 may be configured to calculate the warpage amount of the wafer W in each suction region D. As shown in FIG. For example, the diagnosis unit 334 may calculate the flow conductance in each suction region D based on the mass flow rate _QESC of the thermally conductive gas supplied to each suction region D and the wafer back surface pressure _Pwafer , and based on the flow conductance, calculate each The warpage amount of the wafer W in the suction region D. For example, the diagnosis unit 334 may calculate each adsorption area using table data that indicates the relationship between the value of the conductivity (or the mass flow rate Q _ESC and the wafer back pressure P _wafer ) and the warpage amount determined in advance by experiments or the like The amount of warpage of D. In addition, the diagnosis unit 334 may be configured to estimate each suction region using a machine learning model that calculates the correlation between the value of the flow conductivity (or the mass flow rate Q _ESC and the wafer backside pressure P _wafer ) and the warpage amount by machine learning The amount of warpage of D.

Furthermore, the flow rate target setting unit 335 is configured to set the flow rate target value Q _t introduced into each gas supply line 32 so that the wafer back surface pressure P _wafer in each region calculated by the pressure calculation unit 332 becomes a value within a predetermined range, and sent to the valve control unit 336 . Specifically, the flow rate target setting unit 335 is configured to compare the wafer backside pressure P _wafer in each region calculated by the pressure calculation unit 332 with the target value P _t stored in the memory unit 333 in advance, and the difference The flow rate target value Q _t of each gas supply line is set based on a predetermined relational expression calculated in advance by experiment or simulation so that the absolute value is within a predetermined range.

The valve control unit 336 sends a control signal to each of the fluid control valves 46 to control the valve opening. Specifically, the valve control unit 336 compares the mass flow rate Q _in calculated by the flow rate calculation unit 331 with the target value Q _t set by the flow rate target setting unit 335 , and performs feedback control on the opening of the fluid control valve 46 and the like so that the The mass flow rate Q _in calculated by the flow rate calculation unit 331 agrees with the target value Q _t .

According to the electrostatic chuck device 100 of the present embodiment configured in this way, it is possible to grasp the flow rate of the thermally conductive gas flowing in the gas supply line 32 corresponding to each of the regions radially divided between the adsorption surface 111 and the adsorption target surface S Therefore, by controlling the flow rate to control the wafer backside pressure P _wafer in each region, the uniformity of the surface temperature distribution of the wafer W can be improved. Here, since the first pressure sensor 41 is not provided on each gas supply line 32 individually, but the first pressure sensor 41 is provided on the common line 31 for common use, the number of parts can be reduced and the number of parts can be reduced. To reduce the manufacturing cost, the first pressure sensor 41 measures the primary side pressure of the first flow resistance element 44 required to calculate the flow rate of the thermally conductive gas flowing in each gas supply line 32 .

In addition, this invention is not limited to the said embodiment.

For example, as shown in FIG. 7 , the gas supply system 3 of another embodiment may include a second gas introduction line 35 . A gas supply source (not shown) is connected to the upstream side of the second gas introduction line 35 for introducing a second gas different from the thermally conductive gas to each of the gas supply lines 32 . Examples of the second gas include inert gases such as nitrogen and argon, and CF ₄ . The second gas introduction line 35 is connected to the upstream side of the first flow resistance element 44 in each of the gas supply lines 32 , and is shared among the gas supply lines 32 . The second gas introduction line 35 is provided with a fourth pressure sensor 48 for measuring the pressure of the second gas introduced into each gas supply line 32 . The fourth pressure sensor 48 is configured to measure the pressure and temperature of the second gas passing therethrough.

In this case, the flow rate calculation unit 331 is configured based on the inherent flow rate characteristic of the first flow resistance element 44 , the primary side pressure P ₄ of the first flow resistance element 44 , and the secondary pressure of the first flow resistance element 44 . The side pressure P ₂ is used to calculate the mass flow rate Q _cl of the second gas introduced from the second gas introduction line 35 to each gas supply line 32 . The specific calculation method of the mass flow rate Q _cl is the same as that of the above-described calculation method of the mass flow rate Q _in of the thermally conductive gas.

In addition, in the electrostatic chuck device 100 of another embodiment, as shown in FIG. 8 , the gas supply system 3 may not include the leakage line 34 . In this case, the pressure calculation unit 332 is configured to calculate P _wafer with "Q _VAC =0" in the above-mentioned formula (3).

In addition, in the said embodiment, although the 2nd flow resistance element 45 is provided in all the some through-holes 113, it is not limited to this. In other embodiments, only a part of the plurality of through holes 113 may be provided with the second flow resistance element 45 .

In addition, in the said embodiment, although the 1st flow resistance element 44, the 2nd flow resistance element 45, and the 3rd flow resistance element 342 are laminar flow element resistance bodies, it is not limited to this. The first flow resistance element 44 , the second flow resistance element 45 , and the third flow resistance element 342 may be any one as long as they have flow characteristics that determine the flow rate of the passing heat-conductive gas according to the pressure on the primary side and the pressure on the secondary side. resistance body.

In addition, the first flow resistance element 44 , the second flow resistance element 45 and the third flow resistance element 342 may not be resistance bodies provided in the flow path of the gas supply line 32 . The first flow resistance element 44 , the second flow resistance element 45 and the third flow resistance element 342 can be, for example, the flow paths themselves included in the gas supply line 32 with known flow characteristics. Even with such a configuration, the mass flow rate of the thermally conductive gas introduced into each gas supply line 32 or the wafer backside pressure in each adsorption region can be grasped by utilizing the flow rate characteristics of the flow path.

In addition, in the said embodiment, although all the some gas supply lines 32 are connected to the common line 31, it is not limited to this. In other embodiments, only a part (two or more) of the plurality of gas supply lines 32 may be connected to the common line 31 .

In addition, in the said embodiment, although the common line 31 is connected to the upstream end of each gas supply line 32, it is not limited to this. The common line 31 of other embodiments can be connected to any position as long as it is on the upstream side of the first flow resistance element 44 in each gas supply line 32 .

In addition, although the gas supply system 3 of the said embodiment is used together with the electrostatic chuck apparatus 100, it is not limited to this. The gas supply system 3 of the other embodiment can also be used together with a vacuum chuck device that sucks an object such as a wafer by vacuum suction, and supplies heat conduction to the space between the suction surface of the vacuum chuck device and the suctioned surface of the object. Sexual gas.

In addition, in the gas supply system 3 of the said embodiment, although the whole surface of the adsorption|suction surface 111 is divided into a radial shape (pizza cut shape), and several adsorption|suction area|regions D are set, it is not limited to this. In another embodiment, as shown in FIG. 9 , the suction surface 111 may be divided into a plurality of (here, three) suction regions D ₁ to D ₃ that are set in concentric circles. In addition, the annular adsorption area may be radially divided into a plurality of adsorption areas. Here, the outermost annular adsorption region _D3 is radially divided into a plurality of (for example, seven) adsorption regions. _In this way, by controlling the flow rate of the thermally conductive gas flowing in each _of the gas supply lines 32 corresponding to the inner adsorption region D1 and the adsorption region _D2 , the wafers in each _of the regions D1 and D2 can be controlled. The back pressure can improve the uniformity of the surface temperature distribution of objects such as wafers W. In addition, by monitoring the pressure of the thermally conductive gas supplied from each gas supply line 32 corresponding to each of the adsorption regions further divided into the outermost adsorption region _D3 , it is possible to detect the local gas pressure along the circumferential direction of the wafer W. warping occurs. In addition, the adsorption area on the inner side of the radially divided annular adsorption area _D3 may not be divided into a plurality of areas in a concentric circle, and as shown in FIG. 10 , only a single circle may be formed. adsorption area D ₁ . In addition, the radially divided annular suction region _D3 may not be the outermost annular region, and as shown in FIG. 11 , the annular suction region D4 may be further set _on the outer side. .

In addition, the diagnosis unit 334 in the above-described embodiment is configured to diagnose abnormalities such as local warpage of the wafer W based on the wafer backside pressure P _wafer in each region calculated by the pressure calculation unit 332 , but is not limited to this. In another embodiment, the diagnosis unit 334 may be configured to be based on the mass flow rate Q _ESC of the thermally conductive gas supplied from each gas supply port 3 a (that is, each area set in a radial shape) calculated by the pressure calculation unit 332 , Abnormalities such as local warpage of the wafer W are diagnosed.

In addition, this invention is not limited to the said embodiment, It cannot be overemphasized that a various deformation|transformation is possible in the range which does not deviate from the summary. [Industrial Availability]

According to the present invention, in the gas supply system for an electrostatic chuck device, the uniformity of the surface temperature distribution of an object such as a wafer can be improved, and the number of parts can be reduced, thereby reducing the manufacturing cost.

1: Electrostatic chuck unit 2: Cooling unit 3: Gas supply system 3a: Gas supply port 5: Flow path forming member 11: Adsorption plate 12: Internal electrode 13: Power source 21: Base plate 31: Common line 32: Gas supply line 33 : control device 34 : leakage line 35 : second gas introduction line 40 : fluid control valve 41 : first pressure sensor 42 : second pressure sensor 43 : third pressure sensor 44 : first flow resistance element 45: Second flow resistance element 46: Fluid control valve 47: Thermometer 48: Fourth pressure sensor 51: Flow path (resistance flow path) 100: Electrostatic chuck device 111: Adsorption surface (upper surface) 112: Lower surface ( Back) 113: Through hole 211: Cooling surface (upper surface) 212: Refrigerant flow path 321: Through flow path 331: Flow rate calculation unit 332: Pressure calculation unit 333: Memory unit 334: Diagnosis unit 335: Flow rate target setting unit 336: Valve control unit 341: Bypass line 342: Third flow resistance element 343: On-off valve 344: Vacuum pump C: Vacuum chambers D, D ₁ to D ₄ : Adsorption area G: Space P _J : Connection points P ₁ , P ₃ , P ₄ : Primary side pressure P ₂ , P _VAC : Secondary side pressure Q _in , Q _VAC , Q _ESC : Mass flow rate S: Adsorbed surface _Tin , T _ESC , T _VAC : Temperature W: Wafer (object )

FIG. 1 is a schematic diagram showing the overall configuration of the electrostatic chuck device according to the present embodiment. 2 is a cross-sectional view schematically showing the configuration of the electrostatic chuck device of the embodiment. 3 is a perspective view schematically showing the configuration of an electrostatic chuck unit and a cooling unit according to the embodiment. FIG. 4 is a plan view showing a suction region set on the suction surface according to the embodiment. FIG. 5 is a diagram schematically showing the configuration of the gas supply system of the embodiment. FIG. 6 is a functional block diagram showing the configuration of the control device according to the embodiment. FIG. 7 is a diagram schematically showing a configuration of a gas supply system according to another embodiment. FIG. 8 is a diagram schematically showing the configuration of a gas supply system according to another embodiment. 9 is a plan view showing a suction region set on the suction surface according to another embodiment. 10 is a plan view showing a suction region set on the suction surface according to another embodiment. 11 is a plan view showing a suction region set on the suction surface according to another embodiment.

3: Gas supply system

3a: Gas supply port

31: Shared pipeline

32: Gas supply line

33: Controls

34: Leak line

40: Fluid Control Valve

41: The first pressure sensor

42: Second pressure sensor

43: The third pressure sensor

44: First flow resistance element

45: Second flow resistance element

46: Fluid Control Valve

47: Thermometer

100: Electrostatic chuck device

341: Bypass line

342: Third flow resistance element

343: On-off valve

344: Vacuum Pump

P ₁ , P ₃ : Primary side pressure

P _J : connection point

Q _in , Q _VAC , Q _ESC : mass flow

P ₂ , P _VAC : Secondary side pressure

T _in , T _ESC : temperature

W: Wafer (object)

Claims (14)

A gas supply system for an electrostatic chuck device that supplies a thermally conductive gas to a space between an attracting surface of an electrostatic chuck device that attracts an object by electrostatic force and a surface to which the object is attracted, the gas supply for the electrostatic chuck device The system includes: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; a common line connected to each gas supply line, into which the thermally conductive gas is introduced; and a flow rate calculation unit for calculating the flow rate of the thermally conductive gas introduced into the respective gas supply lines from the common line, and The flow rate calculation unit is based on a flow rate characteristic of a first flow resistance element provided in each of the gas supply lines, a primary pressure of the first flow resistance element, and a secondary pressure of the first flow resistance element, Calculate the flow rate of the thermally conductive gas introduced into each of the gas supply lines, A pressure sensor measuring the primary side pressure is provided on the common line. The gas supply system for an electrostatic chuck device according to claim 1, wherein: A fluid control valve is provided downstream of the first flow resistance element in each of the gas supply lines, The gas supply system for the electrostatic chuck device is configured to feedback-control the opening degree of the fluid control valve based on the flow rate calculated by the flow rate calculation unit. The gas supply system for an electrostatic chuck device according to claim 2, wherein: A second flow resistance element is provided downstream of the fluid control valve in each of the gas supply lines, The gas supply system for the electrostatic chuck device further includes a pressure calculation unit that calculates the pressure of the thermally conductive gas in each of the regions, The pressure calculation unit calculates each of the pressures on the primary side of the second flow resistance element, the flow rate of the thermally conductive gas passing through the second flow resistance element, and the flow rate characteristic of the second flow resistance element. pressure of the thermally conductive gas in the region. The gas supply system for an electrostatic chuck device according to claim 3, wherein: Each of the gas supply lines includes a gas supply flow path opened on the adsorption surface, In each of the gas supply lines, the second flow resistance element is provided in the gas supply flow path. The gas supply system for an electrostatic chuck device according to claim 3 or claim 4, wherein, The pressure calculation unit calculates all the flow rates passing through the second flow resistance element based on the flow rate calculated by the flow rate calculation unit and a relational expression of a material balance representing the flow rate of the thermally conductive gas in the gas supply line. flow rate of the thermally conductive gas. The gas supply system for an electrostatic chuck device according to any one of Claims 3 to 5, further comprising a diagnosis unit that compares the calculated pressure of the thermally conductive gas with a predetermined reference pressure, An abnormality in the pressure value of the thermally conductive gas in each of the regions is diagnosed. The gas supply system for an electrostatic chuck device according to any one of claim 3 to claim 6, wherein, The flow rate of the thermally conductive gas introduced into each of the gas supply lines is adjusted so that the pressure of the thermally conductive gas calculated by the pressure calculation unit becomes a value within a predetermined range. The gas supply system for an electrostatic chuck device according to any one of claim 1 to claim 7, wherein, The plurality of regions are regions set by dividing the space into radial shapes. The gas supply system for an electrostatic chuck device according to any one of claim 1 to claim 7, wherein, The plurality of regions are regions set by dividing the space into concentric circles and further dividing the annular region therein into radial shapes. The gas supply system for an electrostatic chuck device according to claim 8 or claim 9 that references claim 6, wherein, The diagnostic unit is configured to diagnose based on the mass flow rate of the thermally conductive gas supplied to each of the radially divided regions or the pressure of the thermally conductive gas in each of the radially divided regions Whether or not the object is warped. The gas supply system of any one of claim 1 to claim 10, wherein, The thermally conductive gas is helium. The gas supply system for an electrostatic chuck device according to any one of Claims 1 to 11, further comprising a second gas introduction line connected to the gas supply lines of the respective gas supply lines upstream of the first flow resistance element, a second gas different from the thermally conductive gas is introduced into each of the gas supply lines, The flow rate calculation unit calculates each gas introduced into the gas based on the flow rate characteristic of the first flow resistance element, the primary side pressure of the first flow resistance element, and the secondary side pressure of the first flow resistance element the flow of the second gas to the supply line, A pressure sensor for measuring the primary side pressure is provided on the second gas introduction line. A gas supply method for supplying a thermally conductive gas to a space between an attracting surface of an electrostatic chuck device that attracts an object by electrostatic force and a surface to be attracted to the object, wherein: The electrostatic chuck device includes: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; and a common line connected to the respective gas supply lines for supplying the respective gases to the The supply line introduces the thermally conductive gas, The gas supply method is based on flow characteristics of a first flow resistance element provided on each of the gas supply lines, a primary pressure of the first flow resistance element, and a secondary pressure of the first flow resistance element , to calculate the flow rate of the thermally conductive gas introduced into the respective gas supply lines from the common line, A measurement value of a pressure sensor provided on the common line is used as the primary side pressure. A program for a gas supply system for supplying a thermally conductive gas to a space between an attracting surface of an electrostatic chuck device that attracts an object by electrostatic force and a surface to be attracted to the object, wherein: The electrostatic chuck device includes: a plurality of gas supply lines for supplying the thermally conductive gas to each of a plurality of regions set in the space; and a common line connected to each gas supply line for supplying each of the gases The supply line introduces the thermally conductive gas, The program for the gas supply system causes the computer to function as a flow rate calculation unit based on the flow rate characteristic of the first flow rate resistance element provided in each of the gas supply lines, and the flow rate of the first flow rate resistance element. The primary side pressure and the secondary side pressure of the first flow resistance element are used to calculate the flow rate of the thermally conductive gas introduced into the respective gas supply lines from the common line, The flow rate calculation unit uses a measurement value of a pressure sensor provided on the common line as the primary pressure.

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