JP3042786B2 - Temperature measurement method and temperature control method and device for workpiece in vacuum - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for measuring the temperature of an object to be processed in a vacuum and a method and apparatus for controlling the temperature.

[Conventional technology]

The temperature of the workpiece during processing in conventional vacuum processing such as sputtering, CVD, and dry etching is one of the important processing conditions. As a method of measuring the temperature of the processing target (substrate) in vacuum, a thermocouple or the like is used. A contact type using a temperature sensor is simple and frequently used, and this conventional measuring method is disclosed in
As described in Japanese Patent Application Laid-Open No. -50462, generally, a temperature sensor is pressed against a substrate being processed with a constant force, and the temperature of a temperature measuring section at the tip of the sensor is approximated to the substrate temperature to measure the temperature. However, as is well known to those skilled in the art, the contact thermal resistance is large in a vacuum, and a large error may occur between the display value of the temperature sensor and the substrate temperature.

As a conventional method for controlling the temperature of a substrate, for example, as described in JP-A-60-115226, a substrate is electrostatically attracted to a holding table maintained at a constant temperature, and a heat is applied between the holding table and the substrate. A method of controlling a substrate temperature by interposing a conductive gas is known. This method is effective as a method for controlling the temperature of the object to be processed in vacuum, but when the thermal conditions such as the amount of incident heat fluctuate because the temperature of the target substrate is not actually measured,
The substrate temperature also fluctuates, and more accurate temperature control has been desired.

[Problems to be solved by the invention]

In the above prior art, when measuring the temperature of the target substrate, since the thermal resistance between the substrate and the temperature sensor is unknown, there has been a problem that the temperature error caused by this cannot be taken into account.
In addition, there is a problem that the temperature cannot be accurately controlled by adjusting the temperature control conditions for each substrate.

The inventors of the present application have calculated and studied the error between the temperature sensor display value and the substrate temperature due to a large contact thermal resistance in a vacuum, which is a problem of the prior art, as follows. FIG. 2 schematically shows the flow of heat into and out of the substrate and the temperature measuring unit. Here, the substrate 2 is held on the holding table 1, and the temperature sensor 4 penetrates through a hole 3 provided in a part of the holding table 1 and is pressed against the substrate 2 with a constant force. Per unit area q _b is the substrate 2
Is applied to the substrate 2 in accordance with the remaining heat amount of the heat amount flowing out to the holding table 1 in proportion to the heat transfer coefficient α _W (reciprocal of the thermal resistance).
Rises in temperature. The amount of heat proportional to the heat transfer coefficient α _j between the substrate 2 and the temperature sensor 4 flows into one of the temperature sensors 4, and the temperature measuring unit 5 of the temperature sensor 4 rises in temperature according to the heat capacity Y _j . Here, q _b is a one-dimensional flow that is uniform in the substrate 2 and has no heat flow in the plane direction. The temperature measuring section 5 at the sensor tip is very small and the inside of the temperature measuring section has a uniform temperature. Further, the temperature sensor section downstream of the temperature measuring section 5 has a low thermal conductivity, and the heat flowing out of the temperature measuring section downstream is low. Assume not. Calculations based on this assumption show less error than in practice.

FIG. 3 shows an example of the response of the temperature indicated by the substrate 2 and the temperature sensor 4 as a result of the calculation shown in FIG. When the horizontal axis represents time τ and the vertical axis represents temperature, the sensor temperature indicated by a dashed line with respect to the substrate temperature change indicated by a solid line in the case of constant values of q _b , T _H , Y _J , α _W , and α _j Is larger than the substrate temperature, and the smaller α _j is, the larger the difference is. When the response of the temperature sensor 4 shown in FIG. 3 is empirically determined, α _j is considered to be about 150 W / m ² ° C or less, and it can be seen that the error in the contact temperature measurement in vacuum is large. In addition, since this error changes due to fluctuations in thermal conditions such as the amount of incident heat and the contact state between the substrate 2 and the holding table 1, a value obtained by adding a constant value to the temperature sensor indication value as an error is used as the true substrate value. The result is that it cannot be considered as temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for measuring the temperature of an object to be processed in a vacuum, and a method and apparatus for controlling the temperature, which can accurately measure the temperature of a target substrate and accurately control the temperature to a predetermined temperature.

[Means for solving the problem]

In order to achieve the above object, in the method for measuring the temperature of an object to be processed in a vacuum according to the present invention, the object to be processed is contacted with a contact-type thermometer on a surface of the object to be processed which is opposite to the surface to be processed. The temperature of the object to be processed is measured a plurality of times, and the data on the temperature of the object to be processed obtained by the plurality of measurements is used. Is determined, and the temperature of the object to be processed is calculated from the thermal equilibrium equation using the unknown value determined, or the temperature of the object to be processed is brought into contact with the object to be processed held on a holding table by contacting the temperature. The temperature of the object is measured a plurality of times, and the data between the object, the holding table, and the contact-type thermometer in the vacuum chamber is used by using the data on the temperature of the object obtained by measuring the plurality of times. Calculating the temperature of the object to be processed from a plurality of thermal equilibrium equations.

In the temperature control method, a contact-type thermometer is brought into contact with a surface of the object to be processed which is opposite to the surface to be processed, and the temperature of the object is measured a plurality of times. Using the data on the temperature of the object to be processed, an unknown number in the thermal equilibrium between the object to be processed and the contact thermometer in the vacuum chamber is determined, and the determined unknown number is used by using the determined unknown number. Calculate the temperature of the processing object from a thermal equilibrium equation, and control or hold the temperature of the processing object via a holding table having the temperature control function based on the calculated temperature of the processing object. The temperature of the object to be processed is measured a plurality of times by bringing a contact thermometer into contact with the object to be processed held on a table, and the data is measured using the data about the temperature of the object to be processed obtained multiple times. Between the object to be processed, the holding table, and the contact thermometer inside the vacuum chamber Calculating the temperature of the processing object from a plurality of thermal equilibrium equations, and controlling the temperature of the processing object via a holding table having the temperature control function based on the calculated temperature of the processing object. It was done.

Further, the temperature control device includes an in-vacuum processing means provided in the vacuum vessel, a means for holding an object to be processed having a suitable positional relationship with the in-vacuum processing means, and an object mounted on a part of the holding means. It has a temperature measuring means for the processed object and a temperature control means provided inside or outside the holding means, and the temperature measuring means performs the processing on the basis of a plurality of temperature measurement data in the contact-type temperature measurement of the processing object in the vacuum. By calculating the unknowns in the thermal equilibrium equation between the object and the temperature sensor, or by solving the same number or more of the thermal equilibrium equations with unknown variables created from multiple temperature measurement data, This is achieved by calculating the temperature and controlling the temperature of the object to be processed by the temperature control means operating based on the measurement result calculated by the temperature measurement means.

[Action]

In the temperature measurement, for example, the temperature of the object to be processed is measured a plurality of times by contacting a contact-type thermometer with the surface opposite to the surface to be processed of the object to be processed during the processing, and the plurality of times is measured and obtained. Using the data on the temperature of the object to be processed, an unknown number in a thermal equilibrium equation between the object to be processed and the contact thermometer inside the vacuum chamber is determined, and from the thermal equilibrium equation using the determined unknown number. The temperature of the object to be processed can be accurately calculated together with the thermal resistance and the like.

In the temperature control, for example, the temperature of the processing target is controlled via a holding table having a temperature control function based on the temperature of the processing target calculated as described above.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of a film forming apparatus showing one embodiment of a method for measuring the temperature of a workpiece in vacuum and a method and apparatus for controlling the temperature according to the present invention.

First, the configuration of the film forming apparatus will be described. A film forming means 12 is arranged above a vacuum vessel 11, and a holding table 1 is arranged on a base 13 at a position facing the film forming means 12, and a substrate (object to be processed) 2 is It is placed on the holding table 1. The temperature sensor 4 is mounted so as to be able to come into contact with the substrate 2 at a constant pressure through the base 13 and the central hole 3 of the holding table 1. The holding table 1 has a built-in electrostatic suction electrode 14, and the substrate 2 can be suctioned to the holding table 1 by a voltage supplied from a holding power supply 15. Cooling gas introduced from piping 16 is
And enters between the substrate 2 and the holding table 1 maintained at a constant temperature to perform heat transfer between the substrate 2 and the holding table 1. The gas pressure in the pipe 16 is maintained at a constant pressure by a flow control valve 19 that adjusts the opening in accordance with a valve opening command issued by a cooling pressure controller 18 that receives a pressure signal from a vacuum gauge 17. For example, a thermocouple 20 of the temperature sensor 4 is connected to a temperature measuring / calculating unit 21. Holding power supply 15, cooling pressure control unit 18, temperature measurement / calculation unit 21
Are respectively connected to the temperature control unit 22, and the temperature control unit 22 is further connected to the central control unit 23. Further, the central control unit 23 is
Is connected to a film forming power supply 24 that supplies film forming power to the apparatus. The inside of the vacuum vessel 11 is maintained at a pressure suitable for the film formation processing of the substrate 2 by a vacuum exhaust unit and a processing gas supply unit (not shown).

Next, the operation of the film forming apparatus having the above configuration will be described. After mounting the substrate 2 on the holding table 1, the film forming power is supplied from the film forming power supply 24 to the film forming means 12 by the film forming command of the central control unit 23, and the substrate 2 is
A film is formed thereon. Further, the temperature measurement / calculation unit 21 receives a temperature measurement command from the temperature control unit 22 according to a temperature command from the central control unit 23, and measures the temperature of the substrate 2 and other heat conditions based on the temperature signal from the thermocouple 20 of the temperature sensor 4 And sends the calculated data to the temperature control unit 22. The temperature control unit 22 compares the calculated data with the set temperature, sends a holding command to the holding power source 15 as necessary, and moves the substrate 2 to the holding table 1 by the supply voltage from the holding power source 15.
A pressure control command is sent to the cooling pressure control unit 18 and the flow control valve 19 of the pipe 16 is controlled by a valve opening command according to the pressure signal of the vacuum gauge 17 from the cooling pressure control unit 18. By maintaining the pressure of the cooling gas at a predetermined value, the substrate 2 is controlled at a predetermined temperature.

Next, a calculation example of the temperature measurement / calculation unit 21 in the operation of the film forming apparatus having the above configuration will be described. The calculation by the temperature measurement / calculation unit 21 is performed by calculating the substrate temperature by calculating an unknown in the thermal equilibrium equation from a plurality of data of the time versus the temperature sensor indicated value, or by calculating the thermal equilibrium of at least the same number as the unknown variables. The formula is used to calculate the thermal resistance and the substrate temperature by solving the equations simultaneously. Here, a case is shown in which thermal equilibrium equations for each of the substrate 2 and the temperature sensor 4 are solved simultaneously.

FIG. 2 is a schematic diagram showing the flow of heat by enlarging the substrate 2 and the temperature measuring section 5 of the temperature sensor 4 in FIG. Second
As shown in the figure, q _b ... The amount of heat incident on the substrate 2 per unit area α _W ... The heat transfer coefficient T _W between the substrate 2 and the holder 1... The substrate temperature T _H. Further, when Y _W ...... capacity τ ...... time per unit area of the substrate 1, the heat balance equation for the substrate temperature T _W is Becomes

Becomes Here, T _W0 : T _W when τ = 0. T _W∞ : T _W when τ = ∞, Becomes Here, α _W is defined as α _C : heat transfer coefficient due to intervening gas α _R : heat transfer coefficient due to radiation. By setting α _W = α _C + α _R , a value considering the influence of radiation heat transfer is taken. Can be. Next, α _j : heat transfer coefficient between the substrate 2 and the temperature sensor 4 T _j : indicated value of the temperature sensor E: constant indicating the amount of heat flowing out to the back of the sensor by the sensor temperature measuring unit 5 T _a : sensor Terminal temperature Y _j : heat capacity of sensor temperature measuring unit 5 Assuming that, thermal equilibrium equation for temperature sensor 4 is: Becomes

Next, a method of calibrating unknowns in the thermal equilibrium equation will be described. (4) T _j is the sensor reading by the formula, can be measured with the temperature change [Delta] T _j / .DELTA..tau per hour. Substrate temperature T
_{If W} is measured using a separate temperature measuring means, the unknowns α _j , E, T _a , and Y _{j in} equation (4) are obtained as follows.

Each data at time τ = i, i + 1, i + 2, i + 3 is represented by subscript i, i + 1, i + 2, i + 3 respectively. Becomes

By solving these four equations simultaneously, the temperature sensor 4
Constants E, T _a , and Y _j are obtained. Substituting this value into equation (4), the unknown variables in equation (4) in the actual measurement system are α _j and
The two T _W. Therefore the substrate temperature T _W during processing performs multiple measurements, to obtain a plurality of formulas for (2) and (4).

For example, when α _W , α _j , T _W , T _W0 , and q _b are unknown, four measurements are performed. As shown in the following equation, the unknown variables are α _W , α _j , T _W , q
_{With b} and T _Wi , T _{Wi + 1} , T _{Wi + 2} , and T _{Wi + 3} , the number of equations is also eight, and a solution can be obtained.

After calculating all unknown variables once by this method,
When the next substrate 2 is subsequently processed, if there is an item that can be regarded as a constant value from the previous measurement, the number of measurements can be reduced. This relationship is shown in Table 1 below.

By this calculation, α _W , α _j (the reciprocals of the thermal resistance) and the instantaneous value T _W of the substrate temperature are obtained, and by substituting into the equation (2), the temperature T _Wi at an arbitrary time τ _i is obtained.
By substituting into the equation (3), the saturation temperature T _W∞ can be obtained.

In the above calculation, α _W and α _j are fixed. However, when T _W increases, the influence of radiation proportional to the fourth power of the absolute temperature increases, and in this case, the relationship between α _W and α _j and the temperature is The constants may be calculated in the same manner as above by increasing the number of measurements as necessary to obtain the constants in the formulas shown.

Then T _Wi or T _W0 calculated by the temperature measurement and computing unit 21 is the temperature control unit 22 at a different time and the target value is temperature controlled by the following method. (2) the substrate temperature T _W As is clear from the equation varies with the incident heat q _b or heat transfer coefficient alpha _W or the temperature T _H of the holder 1 between the substrate 2 and the supporter 1. Here q _b is determined by the processing conditions and T _H is not changed in a short time because the heat capacity of the holder 1, thus the control of the T _W alpha _W
It is effective to change For this purpose, the clearance δ between the substrate 2 and the holding table 1 or the force F for pressing the substrate 2 against the holding table 1 or the pressure P of the heat transfer gas interposed between the substrate 2 and the holding table 1 may be changed. Usually F or P
by. If this F or P is increased, α _W is increased, but by calibrating this relationship in advance,
Force F or pressure P required for controlling the T _W of interest
Set can be controlled on the substrate temperature T _W of interest.

Accordingly, the force F for pressing the substrate 2 against the holding table 1 can be changed by the voltage supplied to the suction electrode 14 according to a holding command from the adjusting unit 22 in the case of the electrostatic suction method, for example. Further, at this time, the temperature distribution in the substrate 2 is measured, and by changing the voltage supplied to each of the adsorption electrodes 14 to change the voltage, the heat transfer coefficient α _W corresponding to the temperature distribution of the substrate 2 is set to a desired value. Temperature distribution can be controlled.

The operation of the temperature measurement / calculation unit 21 and the temperature control unit 22
In this case, the substrate 2 is cooled by depriving the holding table 1 of heat. However, in addition to the above, the holding table 1 is heated by heating the substrate 2 or the holding table 1 is provided with a means for generating radiation heat such as infrared rays. In the case where the substrate 2 is built in and heated, the temperature of the substrate 2 can be similarly measured and controlled.

In the above embodiment, a film forming apparatus for forming a thin film on the substrate 2 has been described. In addition, a processing apparatus for processing a thin film on a substrate, a driving apparatus for driving a thin film into a specific impurity, or a plasma surface modification. It can also be applied to devices and the like.

〔The invention's effect〕

According to the present invention, the temperature of the object to be processed can be accurately measured by calculating the unknown in the thermal equilibrium equation between the object to be processed and the temperature sensor at the time of the contact type measurement of the object to be processed in a vacuum.

Further, the temperature can be accurately controlled to a predetermined temperature by adjusting the temperature control conditions based on the temperature measurement data of the object to be processed. At this time, a predetermined temperature distribution can be controlled by changing the temperature control conditions according to the temperature distribution of the object to be processed.

In this way, in vacuum processing such as film formation, processing, ion implantation, and plasma surface modification, precise control of the temperature of the object to be processed, which affects its characteristics, has the effect of improving the performance and accuracy of the processing. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a film forming apparatus showing one embodiment of the present invention, FIG. 2 is a schematic diagram showing the flow of heat by enlarging a substrate and a temperature sensor section of FIG. 1, and FIG. It is explanatory drawing which shows the response of the instruction | indication temperature of the board | substrate of the figure and a temperature sensor. DESCRIPTION OF SYMBOLS 1 ... Stand, 2 ... Substrate, 3 ... Hole, 4 ... Temperature sensor, 5 ... Temperature measuring part, 11 ... Vacuum container, 12 ... Film forming means,
13 ... Base, 14 ... Adsorption electrode, 15 ... Holding power supply, 16 ...
... Piping, 17 ... Vacuum gauge, 18 ... Cooling pressure controller, 19 ...
Flow control valve, 20 ... Thermocouple, 21 ... Temperature measurement / calculation unit, 22 ...
... Temperature control unit, 23 ... Central control unit, 24 ... Deposition power supply.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 C23C 16/00-16/56 H01L 21/302 G01K 1/00-19 / 00 JICST file (JOIS) INSPEC (DIALOG)

Claims (8)

(57) [Claims] 1. A method for measuring the temperature of an object to be processed in a vacuum chamber, wherein a contact thermometer is brought into contact with a surface of the object to be processed which is opposite to a surface to be processed. Measuring the temperature of the object to be processed a plurality of times, and using the data on the temperature of the object to be processed determined and measured the plurality of times to measure the temperature of the object and the contact-type thermometer inside the vacuum chamber. A method for measuring the temperature of an object to be processed in a vacuum, comprising: determining an unknown in the thermal equilibrium equation between the two; and using the determined unknown to calculate the temperature of the object to be processed from the thermal equilibrium equation. 2. A method for measuring the temperature of an object held on a holding table inside a vacuum chamber, wherein the temperature of the object held on the holding table is brought into contact with a contact-type temperature. The temperature of the object to be processed is measured a plurality of times, and the temperature of the object to be processed, the holding table, and the contact-type temperature in the vacuum chamber using data on the temperature of the object to be processed obtained by the plurality of measurements. A method for measuring the temperature of an object to be processed in a vacuum, comprising calculating a temperature of the object to be processed from a plurality of thermal equilibrium equations between the object and a gauge. 3. A method for controlling the temperature of an object to be processed held on a holding table having a temperature control function inside a vacuum chamber, wherein the surface of the object to be processed is processed. The contact type thermometer is brought into contact with the surface on the opposite side to measure the temperature of the object to be processed a plurality of times, and in the vacuum chamber using data on the temperature of the object to be processed obtained by measuring the plurality of times. Determine the unknown in the thermal equilibrium equation between the object to be processed and the contact thermometer, calculate the temperature of the object to be processed from the thermal equilibrium equation using the determined unknown, and calculate the calculated A method for controlling the temperature of a workpiece in a vacuum, comprising controlling the temperature of the workpiece via a holding table having the temperature control function based on the temperature of the workpiece. 4. A method for controlling the temperature of an object held on a holding table having a temperature control function inside a vacuum chamber, the method comprising: contacting the object held on the holding table. Measuring the temperature of the object to be processed a plurality of times by contacting a thermometer,
Using the data on the temperature of the object to be processed obtained by the plurality of measurements, the object to be processed is obtained from a plurality of thermal equilibrium equations between the object, the holding table, and the contact thermometer in the vacuum chamber. Calculating a temperature of the processing object, and controlling the temperature of the processing object via a holding table having the temperature control function based on the calculated temperature of the processing object. How to control the temperature of things. 5. The processing in a vacuum according to claim 3, wherein the control of the temperature of the processing target is performed in a state where gas is introduced between the processing target and the holding table. How to control the temperature of things. 6. An in-vacuum processing means provided in a vacuum vessel, holding means for holding an object having a suitable positional relationship with the in-vacuum processing means, and an object to be mounted mounted on a part of the holding means. Temperature measurement means, and a temperature control means provided inside or outside the holding means, the temperature measurement means and the processing object from the multiple times temperature measurement data in the contact-type temperature measurement of the processing object in vacuum The temperature of the object to be processed is calculated by calculating the unknowns in the thermal equilibrium equation between the temperature sensor and the unknown variables created from the temperature measurement data multiple times and solving the same number of thermal equilibrium equations. A temperature control device for an object to be processed in a vacuum, wherein the temperature of the object is controlled by a temperature control means which operates based on the calculated result calculated by the temperature measuring means. 7. A temperature measuring means calculates temperatures at a plurality of positions of the object to be processed, and controls a temperature distribution at the plurality of positions of the object to be processed by a temperature control means which operates based on the measurement result calculated by the temperature measuring means. 7. The temperature control device for a workpiece in a vacuum according to claim 6, wherein 8. A holding means for holding an object to be processed by mechanical clamping or electrostatic attraction, and a temperature control means by gas conduction between the object to be processed and a holding table of the holding means or radiant heating from the holding table. The temperature control device for a workpiece in a vacuum according to claim 6, wherein the temperature control device is configured to control the temperature.