JP7418448B2 - Temperature measuring device, temperature measuring method, and program for temperature measuring device - Google Patents

Description

The present invention relates to a temperature measuring device that measures the temperature in a measurement target space based on the absorbance of gas existing in the measurement target space.

As shown in Patent Document 1, for example, in a semiconductor manufacturing process, a process gas is supplied at a predetermined concentration into a chamber containing a silicon substrate, and the silicon substrate is heated by a heater to generate plasma in the chamber. , substrate processing such as film formation and etching is performed.

In such substrate processing, if the temperature distribution (hereinafter also referred to as two-dimensional temperature distribution) in the plane along the face plate direction of the silicon substrate in the chamber is non-uniform, the processing results will also be non-uniform. Put it away.

Therefore, in order to control the above-mentioned two-dimensional temperature distribution, temperature measurement is performed two-dimensionally by tunable diode laser absorption spectroscopy (TDLAS).

Specifically, laser beams of two different wavelengths in which the process gas present in the chamber exhibits infrared absorption are emitted into the chamber, and the absorbance at each wavelength is measured. After the absorbance ratio is calculated from the measured absorbance, the corresponding temperature is calculated based on the absorbance ratio and from the temperature characteristic, which is the relationship between the absorbance ratio and the temperature, which has been experimentally determined in advance.

By the way, when temperature is measured based on the absorbance of a process gas, it is necessary to select at least two wavelengths at which changes in temperature can be easily detected.

However, depending on the type and concentration of process gas, it may be difficult to find two wavelengths suitable for measurement. That is, depending on the process gas, the absorbance spectrum may be broad, and the absorbance ratio may not change much with respect to temperature changes. In addition, the absorbance is also affected by the concentration of the gas, so for example, when the concentration of the process gas is low, the absorbance ratio may not exhibit sufficient sensitivity to temperature changes.

Even if two wavelengths suitable for temperature measurement exist, the temperature characteristics will differ depending on the type of process gas and the wavelength used. For this reason, when a process gas with unknown temperature characteristics is used, a database of temperature characteristics must be created in advance through experiments, and it is very time-consuming to measure temperature based on absorbance.

Japanese Patent Application Publication No. 2012-204692

Meas. Sci. Technol. 9 (1998) 545-562 ECS Journal of Solid State Science and Technology, 7 (11) Q211-Q217 (2018) Characteristic evaluation of two-dimensional temperature distribution measurement in high temperature and high pressure range using CT semiconductor laser absorption method” Transactions of Society of Automotive Engineers of Japan, 2015, Vol. 46, No. 6, p. 1031-1037

The present invention has been made in view of the above-mentioned problems, and provides a temperature measuring device that can measure the temperature in a measurement target space based on absorbance even when a process gas with unknown temperature characteristics is used. The purpose is to provide

The temperature measuring device according to the present invention is a temperature measuring device that measures the temperature in a chamber to which a process gas is supplied or a flow path through which a process gas is passed, and measures the temperature in the target space to be measured. , a laser emission mechanism that emits into the measurement space a laser beam having a wavelength that includes an absorption line of the temperature measurement gas that does not affect the process, and which is a different type of gas from the process gas; A laser detection mechanism that detects laser light; and a temperature calculator that calculates the temperature in the measurement target space based on the output of the laser detection mechanism, and the output of the laser detection mechanism is a temperature measurement gas. The temperature measurement gas is a gas containing hydrocarbon, and the temperature measurement gas is supplied into the measurement target space together with the process gas. Alternatively, after the temperature is measured with the temperature measurement gas and the temperature measurement gas is exhausted from the measurement object space, the process gas is supplied into the measurement object space.

Further, the temperature measurement method according to the present invention is a temperature measurement method that measures the temperature in the measurement target space, with the inside of the chamber to which the process gas is supplied or the inside of the flow path through which the process gas flows as the measurement target space. a gas supply step of supplying a temperature measurement gas, which is a different type of gas from the process gas, into the measurement target space to realize a state in which temperature measurement is possible; and a laser injection mechanism to detect the absorption line of the temperature measurement gas. a laser emitting step of emitting a laser beam having a wavelength including the wavelength into the measurement space, a laser detection step of detecting the laser beam passing through the measurement space by a laser detection mechanism, and the laser detection mechanism in the temperature measurable state. The method is characterized by comprising a temperature calculation step of calculating the temperature in the measurement target space based on the absorbance calculated from the output of.

If this is the case, even if the temperature characteristics of the process gas, which is the relationship between absorbance and temperature, are unknown, it is possible to use a temperature measurement gas with known temperature characteristics without creating a database, etc. The temperature of the measurement target space can be measured.

Furthermore, since the temperature measurement gas is a gas containing hydrocarbons, for example, even if the temperature measurement gas is supplied together with the process gas, it will not affect the substrate processing performed using the process gas in the chamber. It is possible to have no impact, or even if it does have an impact, it can be made to a negligible extent. In other words, the temperature measurement gas can be a gas that does not affect the process carried out by the process gas in the chamber, so that the temperature can be measured in real time even while substrate processing is progressing in the chamber, for example. It is also possible to prevent the quality of substrate processing from being affected even if the temperature measurement gas remains in the chamber.

In addition, if the temperature measurement gas described above is used, the temperature measurement gas with a predetermined concentration or higher is supplied into the measurement target space, and the measured absorbance has sufficient sensitivity to temperature changes. It can be done as shown.

Furthermore, once the temperature characteristics of the temperature measurement gas are created as a database, it can be commonly used in processes using various process gases. Therefore, the effort required for temperature measurement can be significantly reduced.

As a gas that does not react with the process gas and is particularly suitable for absorbance-based temperature measurement, the temperature measurement gas contains a compound selected from the group consisting of CH ₄ , C ₂ H ₆ , and C ₃ H ₈ . Examples include those containing at least one.

Even if the temperature measurement gas contains O ₂ and is supplied during the process, the temperature of the space to be measured can be measured without affecting the process.

In order to enable temperature measurement based on absorbance with sufficient sensitivity, the temperature measurement gas may be supplied into the measurement target space at a predetermined concentration or higher at which the temperature can be calculated.

For example, in order to be able to measure the temperature in the measurement target space not only during purging but also while substrate processing is being performed, a temperature measurement gas is supplied into the measurement target space together with the process gas. It is fine as long as it is something.

A specific configuration for preventing inaccurate temperature calculation by calculating the temperature in the measurement target space only when a temperature measurement gas is present in the measurement target space. As an example, the gas control unit may further include a gas control unit that controls a gas supply mechanism that supplies temperature measurement gas into the measurement target space to realize a state in which temperature measurement is possible; Laser light having a first wavelength and a second wavelength corresponding to two absorption lines is emitted into the measurement target space, and the temperature calculator detects the first wavelength and the second wavelength from the output of the laser detection mechanism. an absorbance ratio calculation unit that calculates an absorbance ratio of the temperature measuring gas; a temperature characteristic storage unit that stores a temperature characteristic that is a relationship between the absorbance ratio of the first wavelength and the second wavelength and the temperature of the temperature measurement gas; and a temperature output unit that outputs the temperature in the measurement target space based on the absorbance ratio and the temperature characteristic, and the temperature calculator outputs the temperature in the measurement target space based on the temperature measurement possible state. An example is one configured to calculate the temperature in the measurement target space based on the measurement target space.

In order to be able to enjoy almost the same effect as the temperature measuring device according to the present invention by updating the program in an existing temperature measuring device, it is necessary to update the absorption line of the temperature measuring gas, which is a different type of gas from the process gas. a laser emitting mechanism that emits a laser beam having a wavelength including a wavelength within a chamber to which a process gas is supplied or a flow path through which the process gas flows into a measurement target space; and a laser beam that has passed through the measurement space is detected. A program for use in a temperature measurement device that measures the temperature in the measurement target space, the program comprising: a laser detection mechanism; A gas control unit that controls a gas supply mechanism to achieve a temperature measurable state, and a temperature in the measurement target space based on the absorbance calculated from the output of the laser detection mechanism in the temperature measurable state. What is necessary is to use a temperature calculator and a program for a temperature measuring device, which is characterized by causing a computer to perform the functions of the temperature calculator.

Note that the temperature measuring device program may be distributed electronically, or may be recorded on a recording medium such as a CD, DVD, HDD, or flash memory.

As described above, according to the temperature measuring device according to the present invention, the temperature measuring gas, which is a gas containing a different type of hydrocarbon than the process gas, is supplied into the measurement target space, and the temperature is determined based on the absorbance of the temperature measuring gas. Therefore, even if the temperature characteristics of the process gas are unknown, the temperature can be calculated without preparing a database of temperature characteristics in advance through experiments or the like. Furthermore, since the concentration of the temperature measurement gas can be easily adjusted to a value suitable for temperature measurement, for example, the sensitivity of absorbance to temperature changes can be increased and accurate temperature measurement can be achieved.

FIG. 1 is a schematic diagram showing a temperature measuring device according to a first embodiment of the present invention. FIG. 1 is a functional block diagram of a temperature measuring device according to a first embodiment. FIG. 2 is a schematic diagram showing a temperature measuring device and a substrate processing system according to a second embodiment of the present invention. FIG. 2 is a schematic perspective view showing the configuration of a laser emitting mechanism and a laser detection mechanism of the temperature measuring device. FIG. 3 is a schematic cross-sectional view showing the structure around the chamber of the temperature measuring device according to the embodiment. FIG. 3 is a functional block diagram of the temperature measuring device according to the embodiment. A modification of the temperature measuring device according to the second embodiment of the present invention.

200...Substrate processing system 100...Temperature measurement device 10...Chamber 20...Laser injection mechanism 30...Laser detection mechanism 40...Control device 44...Temperature calculator 441... Absorbance ratio calculation unit 442...Temperature characteristic storage unit 443...Temperature output unit

Below, a temperature measuring device 100 according to a first embodiment of the present invention will be described.
The temperature measuring device 100 of the first embodiment takes a flow path L for supplying process gas into various chambers 10 or the inside of the chamber 10 as a measurement target space in a semiconductor manufacturing process, and measures the temperature based on absorbance. It is something.

As shown in FIG. 1, the temperature measuring device 100 includes a laser emitting mechanism 20 that is connected to the chamber 10 and that emits a laser beam to a flow path L through which at least a process gas is passed. It includes a laser detection mechanism 30 that detects laser light, and a control mechanism 40 that acquires a light intensity signal of the laser light detected by the laser detection mechanism 30. The laser beam emitted from the laser emitting mechanism 20 is configured to reach the laser detecting mechanism 30 via a transmission window provided in the flow path L.

For example, an etching process is performed within the chamber 10 . When etching silicon, a fluorine carbide gas such as SF ₆ , HBr, and CF ₄ is supplied into the chamber 10 through the flow path L as a process gas.

Furthermore, in the first embodiment, a gas different from the process gas, such as CH ₄ (methane), is also flowed into the flow path L as a temperature measurement gas, either alone or in a mixed state with the process gas. Here, the temperature measurement gas is a gas that does not affect various processes performed in the chamber CH. Note that the supply of the process gas or the temperature measurement gas to the flow path L is controlled by the gas supply mechanism GS provided on the upstream side of the flow path L. In the first embodiment, the control mechanism 40 is configured to calculate the temperature in the measurement target space based on the absorbance of CH ₄ . In addition, when the temperature measurement gas is flowed alone into the flow path L, which is the measurement target space, the temperature measurement device 100 performs temperature measurement based on the absorbance of the temperature measurement gas, and then the flow path L After the temperature measurement gas is exhausted from the chamber CH, a process gas is supplied to the flow path L and the chamber CH by the gas supply mechanism GS. Note that the temperature measuring gas is not limited to methane, and may be alkanes such as C ₂ H ₆ or C ₃ H ₈ or other hydrocarbon gases. Further, the temperature measuring gas may be any gas having an absorption wavelength band in the near-infrared region, and may be, for example, oxygen (O ₂ ).

That is, the laser emitting mechanism 20 emits laser beams with wavelengths corresponding to two different absorption peaks of the temperature measuring gas, and the laser detecting mechanism 30 outputs light intensity signals at the respective wavelengths. Furthermore, the temperature measurement gas does not react with the substrate to be processed or the film formed on the substrate during the process in the chamber 10, or is substantially negligible compared to the effect of the process gas. things are selected. Furthermore, the temperature measuring gas used is one whose temperature characteristics are known in terms of at least two absorption peaks.

More specifically, the control mechanism 40 is physically a dedicated or general-purpose computer equipped with a CPU, an internal memory, an input/output interface, an A/D converter, a D/A converter, etc. As shown in FIG. 2, the CPU and other components work together based on the program for the temperature measuring device, and as shown in FIG. It is configured to perform the functions of the container 44 and the like.

The gas control unit 41 controls the gas supply mechanism GS to supply methane gas, which is a temperature measurement gas, into the flow path L, and realizes a state in which temperature measurement is possible in which the concentration of methane gas is equal to or higher than a predetermined concentration. For example, before the process gas is supplied to the chamber 10, the gas control unit 41 controls the gas supply mechanism GS to supply only methane gas into the flow path L. Here, the concentration of methane gas is set to a concentration value that is equal to or higher than a predetermined concentration and has an absorbance ratio at the first wavelength and the second wavelength that is sufficiently sensitive to temperature changes. Here, the predetermined concentration is, for example, a value such that the detected absorbance is about 10 ^-4 or more than 10 ^-4 .

The laser control unit 42 controls the laser injection mechanism 20 in a state where the temperature measurement gas is supplied to the flow path L from the gas supply mechanism GS under the control of the gas control unit 41. Specifically, the laser control unit 42 controls the current or voltage applied to the laser emitting mechanism 20 to emit laser beams corresponding to a first wavelength and a second wavelength corresponding to the absorption peak of the temperature measuring gas. It is ejected from the mechanism 20.

The light intensity signal acquisition unit 43 digitizes a light intensity signal, which is an output when the laser detection mechanism 30 detects the laser light that has passed through the flow path L, into a light intensity value indicated by the signal, and imports it into the computer.

The temperature calculator 44 calculates the temperature within the measurement target space based on the output of the laser detection mechanism 30. That is, the temperature calculator 44 calculates the corresponding temperature from the absorbance ratio at the first wavelength and the second wavelength generated in methane gas, which is the temperature measurement gas. Here, the temperature calculation algorithm based on the absorbance ratio of the first wavelength and the second wavelength by the temperature calculator 44 is a known algorithm described in, for example, Non-Patent Document 1.

More specifically, the temperature calculator 44 includes an absorbance ratio calculation section 441, a temperature characteristic storage section 442, and a temperature output section 443.

The absorbance ratio calculation unit 441 calculates the absorbance ratio from the light intensity signals of the first wavelength and the second wavelength obtained from the laser detection mechanism 30.

The temperature characteristic storage unit 442 stores the temperature characteristic, which is the relationship between the absorbance ratio of the first wavelength and the second wavelength and the temperature, for the temperature measurement gas. This temperature characteristic is stored in advance as a database created through experiments. Here, the absorbance at the first wavelength is a value that depends on temperature and concentration, and the second wavelength is a value that does not depend on temperature but only on concentration. Therefore, the concentration of the temperature measurement gas can be calculated from the absolute value of the absorbance at the second wavelength. Moreover, the absorbance ratio of the first wavelength and the second wavelength has a unique correspondence with temperature, so that the temperature can be calculated, assuming that the concentration is kept constant.

The temperature output unit 443 refers to the above-described temperature relationship using the calculated absorbance ratio of the first wavelength and the second wavelength, and outputs the corresponding temperature.

According to the temperature measurement device of the first embodiment configured in this way, the temperature of the measurement target space is measured based on the absorbance ratio of the temperature measurement gas different from the process gas. Even if there are no at least two absorption wavelength peaks from which the temperature can be easily calculated in the process gas, the temperature can be easily measured.

Further, since the temperature characteristics of the temperature measurement gas are known, there is no need to create a database of temperature characteristics as a preparation before temperature measurement. Therefore, even if the process gas does not have a known composition as exemplified, but has unknown characteristics, it is possible to measure the temperature of the measurement target space based on the absorbance.

Below, a temperature measuring device 100 and a substrate processing system 200 according to a second embodiment of the present invention will be described with reference to FIGS. 3 to 6.

The substrate processing system 200 of this embodiment is used in a semiconductor manufacturing process, and performs substrate processing such as film formation and etching on a substrate such as a silicon wafer. This substrate processing system 200 includes a chamber 10, a gas supply mechanism GS that supplies various gases into the chamber 10, a gas exhaust mechanism that exhausts the gas inside the chamber 10 to the outside, and a gas exhaust mechanism that uses the inside of the chamber 10 as a measurement target space. It includes at least a temperature measuring device 100 that measures temperature.

Specifically, as shown in FIG. 3, the chamber 10 that accommodates a substrate (not shown) has a process gas supply path L1 that supplies process gas, and a process gas discharge path L2 that discharges the process gas supplied to the chamber 10. are connected. Note that in the second embodiment, SF ₆ is supplied into the chamber 10 as a process gas in order to etch the silicon substrate inside the chamber 10.

The chamber 10 is formed with an internal space S for accommodating a substrate, and this internal space S is provided with a heater H for heating the substrate. Then, the substrate processing described above is performed by heating the substrate with the heater H and generating plasma in the internal space S of the chamber 10 while supplying process gas to the chamber 10.

The chamber 10 is formed with a plurality of supply ports P1 through which process gas is supplied and an exhaust port P2 through which the process gas supplied to the internal space S is discharged.

The process gas supply path L1 has one end connected to the above-mentioned supply port P1, and the other end connected to the process gas source Z1. Here, a process gas supply path L1 is connected to each of the plurality of supply ports P1, and these plurality of process gas supply paths L1 are provided in parallel with each other. Thereby, the flow rate and the like of the process gas flowing through each process gas supply path L1 can be independently controlled.

Each process gas supply path L1 is provided with a part of a gas supply mechanism GS made up of a plurality of fluid devices. Specifically, the gas supply mechanism GS includes one or more on-off valves V1 provided in each process gas supply path L1, and a first fluid control device MFC1 that controls physical quantities such as the flow rate and pressure of the process gas. ing. The first fluid control device MFC1 here is a differential pressure type or thermal type mass flow controller that controls the flow rate of the process gas flowing into the process gas supply path L1, calculates the actual flow rate flowing into the process gas supply path L1, and calculates the actual flow rate flowing into the process gas supply path L1. A fluid control valve (not shown) is controlled so that the flow rate approaches a target flow rate input in advance.

Further, each process gas supply path L1 is connected to a temperature measurement gas supply path L3 through which a temperature measurement gas such as methane gas, which is different from the process gas, flows. , are provided in parallel with each other. Thereby, the flow rate and the like of the temperature measuring gas flowing through each temperature measuring gas supply path L3 can be independently controlled. In the second embodiment, a laser beam having a wavelength corresponding to the absorption line of methane gas is introduced into the chamber 10, and its absorbance is measured.

Each temperature measurement gas supply path L3 has one end connected to the process gas supply path L1, and the other end connected to a gas source Z2 of the temperature measurement gas. Moreover, a part of the gas supply mechanism GS is provided on each temperature measurement gas supply path L3. Specifically, the gas supply mechanism GS includes one or more on-off valves V2 provided on each temperature measurement gas supply path L3, and a second fluid control that controls physical quantities such as the flow rate and pressure of the temperature measurement gas. The device further includes a device MFC2. The second fluid control device MFC2 here is, like the first fluid control device MFC1 described above, a differential pressure type or thermal type mass flow controller that controls the flow rate of the temperature measuring gas.

Further, each process gas supply path L1 is connected to a temperature measurement gas supply path L3 through which a temperature measurement gas such as methane gas, which is different from the process gas, flows. , are provided in parallel with each other. Thereby, the flow rate and the like of the temperature measuring gas flowing through each temperature measuring gas supply path L3 can be independently controlled. In the second embodiment, a laser beam having a wavelength corresponding to the absorption line of methane gas is introduced into the chamber 10, and its absorbance is measured.

Each temperature measurement gas supply path L3 has one end connected to the process gas supply path L1, and the other end connected to a gas source Z2 of the temperature measurement gas. Moreover, a part of the gas supply mechanism GS is provided on each temperature measurement gas supply path L3. Specifically, the gas supply mechanism GS includes one or more on-off valves V2 provided on each temperature measurement gas supply path L3, and a second fluid control that controls physical quantities such as the flow rate and pressure of the temperature measurement gas. The device further includes a device MFC2. The second fluid control device MFC2 here is, like the first fluid control device MFC1 described above, a differential pressure type or thermal type mass flow controller that controls the flow rate of the temperature measuring gas.

Further, each material gas supply path L1 is connected to a dilution gas supply path L4 through which a diluent gas such as nitrogen gas for diluting the process gas flows, and these plurality of dilution gas supply paths L4 are provided in parallel with each other. It is being Thereby, the flow rate and the like of the diluent gas flowing through each diluent gas supply path L4 can be independently controlled.

Each diluent gas supply path L4 has one end connected to the process gas supply path L1 and the other end connected to a dilution gas source Z3, and has one or more on-off valves V3 and a dilution gas flow rate and A third fluid control device MFC3 that controls physical quantities such as pressure is provided. The second fluid control device MFC3 here is, like the first fluid control device MFC1 described above, a differential pressure type or thermal type mass flow controller that controls the flow rate of the diluent gas.

The process gas discharge path L2 has one end connected to the above-mentioned discharge port P2, and the other end connected to, for example, a suction pump P located outside the chamber 10. This process gas discharge path L2 is provided with a pressure regulating means V4 such as a pressure regulating valve and an on-off valve V5 which constitute a gas discharge mechanism.

As shown in FIG. 4, the temperature measuring device 100 of this embodiment includes a laser emitting mechanism 20 that emits a laser beam into the chamber 10 so as to cross the inside of the chamber 10, and each laser beam that passes through the chamber 10. The apparatus further includes a laser detection mechanism 30 that detects light, and a control mechanism 40 that acquires light intensity signals of each laser beam detected by the laser detection mechanism 30 and controls operations of various devices. Here, the configurations of the chamber 10, the laser emitting mechanism 20, and the laser detection mechanism 30 are known, for example, as described in Non-Patent Document 2.

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

The chamber body 11 has, for example, an inner circumferential surface forming an internal space S in the shape of a rotating body, and an outer circumferential surface in which an entrance window W1 and an exit window W2 through which laser light is transmitted are formed. Further, the bottom wall of the chamber body 11 is formed with one discharge port P2 mentioned above. Note that the number and arrangement of the discharge ports P2 may be changed as appropriate.

The chamber body 11 of this embodiment has a polygonal outer peripheral surface, and an entrance window W1 is formed on one side of a pair of opposing sides of the outer peripheral surface, and an exit window W2 is formed on the other side. There is. The outer peripheral surface here is octagonal, and as shown in FIG. 4, an entrance window W1 is formed on one side, and an exit window W2 is formed on the side opposite to the entrance window W1.

Furthermore, one laser optical path X is formed in the chamber body 11, passing through the inner circumferential surface and the outer circumferential surface. This laser optical path X is formed along a plane perpendicular to the central axis C of the internal space S, in other words, along the substrate accommodated in the internal space S.

The upper lid member 12 constitutes the upper wall of the chamber 10, and has, for example, a circular flat plate shape in which the plurality of supply ports P1 described above are formed. The plurality of supply ports P1 are arranged, for example, at equal intervals on the circumference in a top view, and here, the four supply ports P1 are arranged at equal intervals around the central axis C of the internal space S. Note that the number and arrangement of the supply ports P1 may be changed as appropriate.

The porous member 13 is arranged below the upper lid member 12 with a gap in between. Thereby, the internal space S is partitioned into an upper space S1 above the porous member 13 and a lower space S2 below the porous member 13. A large number of small holes h1 penetrating in the thickness direction are formed in this porous member 13, and the process gas supplied from the supply port P1 to the upper space S1 is distributed to the lower space h1 while being dispersed in the lower space. It is made to spread throughout S2.

The lower lid member 14 is formed with a plurality of through holes h2 that guide the process gas supplied to the internal space S to the exhaust port P2, and here also serves as a substrate holding member on which a substrate (not shown) is placed. used. The lower lid member 14 is, for example, in the shape of a circular flat plate in which a plurality of through holes h2 are formed at positions corresponding to, for example, the above-mentioned supply ports P1. Further, a plurality of heaters H such as cartridge heaters are provided on the lower surface of the lower lid member.

Next, the laser injection mechanism 20, laser detection mechanism 30, and control mechanism 40 that constitute the temperature measuring device 100 will be explained.

The laser emitting mechanism 20, as shown in FIG. 4, emits a laser beam toward an entrance window W1 formed in the peripheral wall of the chamber 10. Specifically, this laser emitting mechanism 20 includes a laser light source 21 such as a semiconductor laser, guides the laser light emitted from the laser light source 21 through a fiber, and is arranged to face the entrance window W1. It is injected from the injection end 23. Further, the laser light source 21 is configured to emit laser beams having a first wavelength and a second wavelength corresponding to two different infrared absorption lines of methane gas, which is a temperature measurement gas. The laser light source 21 may be composed of, for example, two types of semiconductor lasers, or may be capable of changing the wavelength of the emitted laser light by changing the applied voltage. Here, the first wavelength and the second wavelength may be an absorption line of the temperature measuring gas but not an absorption line of the process gas.

The laser detection mechanism 30 detects laser light that passes through the chamber 10 and exits from an exit window W2 formed in the peripheral wall of the chamber 10, as shown in FIG. Specifically, this laser detection mechanism 30 has a laser detection section 31 which is an end of the fiber for detecting the laser light emitted from the fiber and passed through the internal space S, and the laser detection section 31 includes: They are arranged opposite to the exit end portion 23 of the fiber so as to sandwich the internal space S therebetween. A light intensity signal indicating the intensity of the laser light detected by the laser detection section 31 is outputted to the control mechanism 40 described above via the amplifier A and the like.

The control mechanism 40 is physically a dedicated or general-purpose computer equipped with a CPU, an internal memory, an input/output interface, an A/D converter, a D/A converter, etc., and the temperature measuring device 100 stored in the internal memory. As shown in FIG. 6, the CPU and other components cooperate based on the program for controlling the gas control unit 41, laser control unit 42, light intensity signal acquisition unit 43, temperature calculator 44, and heater control. It is configured to perform the functions of the section 45 and the like.

The gas control unit 41 controls the gas supply mechanism GS to supply methane gas, which is a temperature measurement gas, into the chamber 10, and achieves a temperature measurement-enabled state in which the concentration of methane gas is equal to or higher than a predetermined concentration. For example, before the process gas is supplied to the chamber 10, the gas control unit 41 controls the gas supply mechanism GS to supply only methane gas into the chamber 10. Here, the concentration of methane gas is set to a concentration value that is equal to or higher than a predetermined concentration and has an absorbance ratio at the first wavelength and the second wavelength that is sufficiently sensitive to temperature changes. Here, the predetermined concentration is, for example, a value such that the detected absorbance is about 10 ^-4 or more than 10 ^-4 .

The laser control unit 42 causes the laser emission mechanism to emit a laser beam into the chamber 10 after the gas control unit 41 causes the concentration of methane gas, which is a temperature measurement gas, in the chamber 10 to reach a predetermined concentration or higher.

The light intensity signal acquisition unit 43 digitizes a light intensity signal, which is an output when the laser detection mechanism detects the laser light that has passed through the chamber 10, into a light intensity value indicated by the signal, and imports it into the computer.

The temperature calculator 44 calculates the temperature within the measurement target space based on the output of the laser detection mechanism 30. That is, the temperature calculator 44 calculates the temperature from the absorbance ratio at the first wavelength and the second wavelength generated in methane gas, which is the temperature measurement gas. Here, the temperature calculated by the temperature calculator 44 is the average temperature within the chamber 10.

More specifically, the temperature calculator 44 includes an absorbance ratio calculation section 441, a temperature characteristic storage section 442, and a temperature output section 443.

The absorbance ratio calculation unit 441 calculates the absorbance ratio from the light intensity signals of the first wavelength and the second wavelength of each optical path obtained from the laser detection mechanism 30.

The temperature characteristic storage unit 442 stores the temperature characteristic, which is the relationship between the absorbance ratio of the first wavelength and the second wavelength and the temperature, for the temperature measurement gas. This temperature characteristic is stored in advance as a database created through experiments. Here, the absorbance at the first wavelength is a value that depends on temperature and concentration, and the second wavelength is a value that does not depend on temperature but only on concentration. Therefore, the concentration of the temperature measurement gas can be calculated from the absolute value of the absorbance at the second wavelength. Moreover, the absorbance ratio of the first wavelength and the second wavelength has a unique correspondence with temperature, so that the temperature can be calculated, assuming that the concentration is kept constant.

The temperature output unit 443 refers to the above-described temperature relationship using the calculated absorbance ratio of the first wavelength and the second wavelength, and outputs the corresponding temperature as the average temperature of the chamber 10.

The heater control unit 45 controls each heater H based on the average temperature calculated by the temperature output unit 443 so that the temperature on the substrate becomes uniform at the target temperature.

According to the temperature measurement device 100 configured in this way, the temperature in the chamber 10, which is the measurement target space, can be measured based on the absorbance of the temperature measurement gas instead of the process gas.

In addition, the temperature measurement gas is selected to have known temperature characteristics and an absorption line in the infrared region at a wavelength that is easy to use for temperature measurement, making it possible to accurately measure temperature based on absorbance. Easy to implement. Furthermore, since the temperature characteristics are known, there is no need to create a database showing the relationship between the absorbance ratio and temperature in advance through experiments or the like.

Therefore, even if the temperature characteristics of the process gas are unknown, accurate temperature measurement can be achieved without requiring any effort before measurement.

In addition, since the gas used for temperature measurement is, for example, methane gas, it is easy to control the concentration in the measurement target space, and by adjusting the concentration to the appropriate concentration for temperature measurement based on absorbance, the absorbance ratio can be adjusted against temperature changes. It can be made to exhibit sufficient sensitivity.

Furthermore, methane gas, which is a temperature measurement gas, has an absorption line in the infrared region and does not react with the process gas, so it does not substantially affect silicon etching in the chamber 10. Therefore, even if the temperature is measured, the quality of the substrate will not be adversely affected.

Furthermore, in this embodiment, after the temperature inside the chamber CH is measured based on the absorbance of the temperature measurement gas, the process gas is supplied into the measurement target space after the temperature measurement gas is exhausted from the chamber CH. It can be used when the reaction is performed at particularly low pressure. That is, it is easier to maintain the inside of the chamber CH in a low pressure state than when the temperature measurement gas and the process gas are introduced into the chamber CH at the same time.

Next, a modification of the second embodiment will be described. Note that the configurations of the chamber 10, laser injection mechanism 20, and laser detection mechanism 30 in this modification are known, for example, as described in Non-Patent Document 2. The temperature measuring device 100 is not limited to having the single-pass laser optical path X described above, but may have a multi-pass laser optical path X. That is, as shown in FIG. 7, the laser emitting mechanism 20 may be configured to emit laser beams from a plurality of locations around the chamber 10, and the laser detection mechanism 30 may be configured to detect each laser beam.

Specifically, the entrance windows W1 are formed on half (four) of the continuous sides of the chamber 10, and the exit windows W2 are formed on the other continuous (four) sides. The laser detection mechanism 20 includes a fiber splitter 22 that splits the laser beam into each fiber, and emits eight parallel laser beams to each side, and detects the laser beam incident from each side in the chamber 10. It is structured so that the light intersects in a grid pattern.

Furthermore, the temperature calculator 44 calculates a two-dimensional temperature distribution within the chamber 10 based on the absorbance detected in each laser optical path X. Further, the control mechanism 40 individually controls each heater H based on the two-dimensional temperature distribution. Specifically, the control mechanism 40 increases the voltage applied to the corresponding heater H for portions of the two-dimensional temperature distribution that are lower than the target temperature, and increases the voltage applied to the corresponding heater H for portions that are higher than the target temperature. decrease.

Other embodiments will be described.

In the embodiment described above, the temperature was calculated based on the absorbance measured when only the temperature measurement gas was present in the measurement target space, but the temperature was calculated when the process gas and temperature measurement gas were present simultaneously. The temperature may be calculated based on the absorbance. With such a device, for example, changes in temperature can be monitored in real time even while substrate processing is being performed in the chamber, and feedback control of the heater can be performed sequentially. In other words, when the temperature measurement gas is supplied into the measurement target space together with the process gas, it takes a shorter time and in real time compared to when the temperature measurement gas and the process gas are supplied separately into the measurement target space. In addition to making it possible to measure temperature, it also becomes possible to simultaneously perform a reaction using a process gas along with temperature measurement.

The measurement target space is not limited to the inside of the chamber to which the process gas is supplied, but may be, for example, a flow path through which the process gas flows. In this case, the temperature can be measured by flowing a temperature measuring gas instead of the process gas into the flow path and measuring the absorbance of the laser beam.

The present invention is not applicable only to the silicon etching process as in each of the embodiments described above, but is also applicable to other processes. For example, the process may be a process for various substrate treatments such as aluminum or III-V semiconductor etching, or a CVD process.

The process gas used in the silicon etching process is a gas containing at least one compound selected from the group consisting of SF ₆ , HBr, CF 4 , and a halogen compound. Furthermore, in the case of an etching process for aluminum or III-V group semiconductors, the process gas is a gas containing at least one compound selected from the group consisting of Cl ₂ , BCl ₂ , SiCl ₄ , and CHCl ₃ . A different type of gas may be used as the temperature measuring gas.

Furthermore, in the MOCVD process, an organic metal material such as trimethyl gallium, trimethyl aluminum, or trimethyl indium is used as a process gas, and a gas different from these may be used as a temperature measurement gas. In either case, methane gas can be used as the temperature measuring gas.

The process gas used in the film forming process may be an insulating film forming gas, a ferroelectric forming gas, or an electrode forming gas. Specifically, the gas for forming an insulating film includes, for example, tetraethoxysilane (TEOS), trimethylborate (TMB), triethylborate (TEB), trimethylolpropane (TMP), trimethylphosphate (TMOP), triethylphosphate (TEOP), Tetrakisethylmethylaminozirconium (TEMAZ), tetrakisdiethylaminohafnium (TDMAH), tert-butyliminotris(ethylmethylamino)tantalum (TBTEMT), trisdimethylaminosilane (3DMAS), zirconium chloride ( _ZrCl4 ), hafnium chloride ( _HfCl4 ) ), tungsten hexachloride (WCl ₆ ), aluminum chloride (AlCl ₃ ), and molybdenum pentachloride (MoCl ₅ ).

Process gases used as ferroelectric forming gases or electrode forming gases include pentaethoxytantalum (Ta(OC ₂ H ₅ ) ₅ ) and tetra-t-butoxyhafnium (Hf(OtC ₄ H ₉ ) ₄ ). , tri-sec-butoxyaluminum (Al(O-sec-C ₄ H ₉ ) ₃ ), bis(ethylcyclopentadienyl)ruthenium (Ru(C ₅ H ₄ C ₂ H ₅ ) ₂ ), bis(dipy (isopropoxy)tris(dipivaloylmethanato)zirconium ₍ Zr( _{OiC 3 H 7} )(C ₁₁ H _{19 O 2} ) ₃ ), It contains at least one compound selected from the group consisting of di(isopropoxy)bis(dipivaloylmethanato)titanium (Ti(OiC ₃ H ₇ ) ₂ (C ₁₁ H ₁₉ O ₂ ) ₂ ).

Examples of temperature measurement gases that are preferable for measuring the temperature in the measurement target space in an etching process or film formation process that uses a process gas containing the above-mentioned compounds include methane (CH ₄ ), C _{2 H 6 , and C 2} H ₆ . Examples include gases containing at least one compound selected from the group consisting of alkanes such as ₃ H ₈ and other hydrocarbons. Since such a temperature measurement gas does not react with the process gas described above, the temperature of the measurement target space can be measured even during the process. Further, for example, if the temperature in the measurement target space is to be measured between processes, the temperature measurement gas may react with the above-mentioned process gas. In such a case, oxygen (O ₂ ) having an absorber in the near-infrared region can be used as the temperature measurement gas.

Note that the temperature measurement gas is not limited to those mentioned above, and other gases with known temperature characteristics may be used. In order to be able to measure temperature based on absorbance, the temperature measuring gas preferably has an absorption wavelength band in the infrared.

When calculating temperature from absorbance, the ratio of the peaks of the first wavelength and the second wavelength was used as the absorbance ratio, but for example, by sweeping the wavelength of the laser light in a predetermined band, The spectral area ratio may be used as the absorbance ratio.

In addition, various modifications of the embodiments and combinations of parts of each embodiment may be made as long as they do not go against the spirit of the present invention.

According to the present invention, it is possible to provide a temperature measuring device that can measure the temperature in a measurement target space based on absorbance even when a process gas whose temperature characteristics are unknown is used.

Claims (8)

A temperature measurement device that measures the temperature in a measurement target space, with the inside of a chamber to which a process gas is supplied or the inside of a flow path through which a process gas flows as a measurement target space,
a laser emitting mechanism that ejects into the measurement target space a laser beam having a wavelength that includes an absorption line of a temperature measurement gas that is a different type of gas from the process gas and does not affect the process;
a laser detection mechanism that detects laser light that has passed through the measurement target space;
a temperature calculator that calculates the temperature in the measurement target space based on the output of the laser detection mechanism,
The output of the laser detection mechanism is generated by a laser beam that passes through the measurement target space in which the temperature measurement gas exists,
The temperature measurement gas is a gas containing hydrocarbons,
The temperature measurement gas is supplied into the measurement target space together with the process gas, or the process gas is supplied after the temperature measurement gas is exhausted from the measurement target space after the temperature is measured with the temperature measurement gas. A temperature measuring device characterized in that: is supplied into the measurement target space. _The temperature measuring device according to claim 1, wherein the temperature measuring gas contains at least one compound selected from the group consisting of _CH4 , _{C2H6 ,} and _C3H8 . 3. The temperature measuring device according to claim 1, wherein the temperature measuring gas contains _O2 and is supplied during the process. The temperature measurement device according to any one of claims 1 to 3, wherein the temperature measurement gas is supplied into the measurement target space at a predetermined concentration or higher at which the temperature can be calculated. The temperature measurement device according to any one of claims 1 to 4, wherein a temperature measurement gas is supplied into the measurement target space together with a process gas. further comprising a gas control unit that controls a gas supply mechanism that supplies a temperature measurement gas into the measurement target space to realize a state in which temperature measurement is possible;
The laser emitting mechanism emits laser beams having a first wavelength and a second wavelength corresponding to two absorption lines of the temperature measurement gas into the measurement target space,
The temperature calculator is
an absorbance ratio calculation unit that calculates an absorbance ratio between a first wavelength and a second wavelength from the output of the laser detection mechanism;
a temperature characteristic storage unit that stores a temperature characteristic, which is a relationship between the absorbance ratio of the first wavelength and the second wavelength and temperature, for the temperature measurement gas;
comprising a temperature output unit that outputs the temperature in the measurement target space based on the calculated absorbance ratio and the temperature characteristic,
The temperature measuring device according to any one of claims 1 to 5, wherein the temperature calculator is configured to calculate the temperature in the measurement target space based on the output of the laser detection mechanism in the temperature measurable state. . A temperature measurement method that measures the temperature in a measurement target space, with the inside of a chamber to which a process gas is supplied or the inside of a flow path through which a process gas flows as a measurement target space, the method comprising :
a gas supply step of supplying a temperature measurement gas, which is a different type of gas from the process gas, into the measurement target space to realize a state in which temperature can be measured;
a laser emitting step of emitting a laser beam having a wavelength including an absorption line of the temperature measuring gas into the measurement target space by a laser emitting mechanism;
a laser detection step of detecting laser light passing through the measurement target space by a laser detection mechanism;
A temperature measuring method, comprising: a temperature calculating step of calculating a temperature in the measurement target space based on the absorbance calculated from the output of the laser detection mechanism in the temperature measurable state. A laser beam of a wavelength including an absorption line of a temperature measurement gas, which is a different type of gas than the process gas, is applied to the chamber to which the process gas is supplied or the flow path through which the process gas flows. A program used in a temperature measurement device that measures the temperature in the measurement target space , and includes a laser emitting mechanism that emits light into a measurement target space, and a laser detection mechanism that detects laser light that has passed through the measurement target space. And ,
a gas control unit that controls a gas supply mechanism that supplies a temperature measurement gas, which is a different type of gas from the process gas, into the measurement target space to realize a state in which temperature measurement is possible;
The computer is characterized in that the computer functions as a temperature calculator that calculates the temperature in the measurement target space based on the absorbance calculated from the output of the laser detection mechanism in the temperature measurable state. Program for temperature measuring devices.

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