JPH0640027B2 - Method for measuring the temperature of an object to be heated in an optical heat treatment apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat treatment apparatus for heat-treating an object to be heat-treated, such as a semiconductor wafer, contained in a quartz process tube by a light irradiation type heating means. The present invention relates to a method for measuring the temperature of a processed material.

2. Description of the Related Art In recent years, a lamp annealing device capable of rapid heating and cooling has been used for annealing an ion-implanted semiconductor wafer. This lamp annealing apparatus heats a wafer placed in a quartz process tube by irradiating light from a halogen lamp, and it is important to control the temperature of the wafer to be heated, but as described below. However, it is difficult to directly measure the temperature of the wafer in the process tube during processing, and thus it is also difficult to accurately control the temperature of the wafer.

It is common to use a thermocouple to measure temperature,
Placing the thermocouple exposed in the process tube is not possible because the process tube is contaminated. To prevent contamination of the process tube, the thermocouple should be covered with a quartz tube and inserted, but in this case,
Due to the influence of the cladding tube, the value measured by the thermocouple becomes much lower than the actual wafer temperature, and the response is poor. Generally, when the wafer temperature is about 1000 ° C, the measured value is 1.
It becomes lower by about 00 to 200 ° C. Thus, with thermocouples,
It is difficult to directly measure the temperature of the wafer in the process tube during processing.

A radiation thermometer is also used to measure the temperature. However,
Since the output wavelength of the halogen lamp is 0.6 to 4.0 μm, when the detection wavelength of the radiation thermometer is 4 μm or less, the measurement is difficult due to the influence of the output wavelength of the lamp. When the temperature detection wavelength is longer than 4 μm, the output wavelength of the lamp has no effect, but the radiant energy is almost absorbed by the quartz process tube.
It is not possible to measure temperature from outside the process tube. Thus, even with a radiation thermometer, it is difficult to directly control the temperature of the wafer in the process tube during processing.

Therefore, in the conventional amplifier annealing apparatus, the temperature control of the wafer is performed as follows. That is, first, before processing an actual wafer to be a product, a dummy wafer is put into a process tube and the same processing as that for the actual wafer is performed. At this time, the exposed thermocouple inserted in the process tube is brought into direct contact with the surface of the dummy wafer to measure the temperature, and the lamp output is adjusted based on the measured value of the temperature so that the dummy wafer reaches the set temperature. After that, the process tube is washed, an actual wafer is put in the process tube, and processing is performed under the same conditions as in the case of the dummy wafer. At this time, since it is difficult to directly measure the temperature of the actual wafer being processed as described above, the actual wafer is set to the set temperature by performing the processing under the same conditions as those of the dummy wafer without measuring the temperature. I am trying to become. For this reason, the temperature control becomes open-loop control, and the actual wafer temperature varies due to the influence of disturbances such as output deterioration due to lamp deterioration and changes in the reflectance of the lamp reflector, making it difficult to perform accurate temperature control. Is.

Problems to be Solved by the Invention As described above, in the conventional heat treatment apparatus, even if a thermocouple or a radiation thermometer is used, the temperature of the heat treatment object in the process tube is directly measured during the heat treatment. Therefore, it is difficult to accurately control the temperature of the object to be heated.

An object of the present invention is to solve such a problem and to provide a method capable of directly and accurately measuring the temperature of an object to be heat-treated in a process tube during heat treatment.

Means for Solving the Problems The method of the present invention is applied to a process tube wall in a light heat treatment apparatus for heat-treating an object to be heat-treated placed in a quartz process tube by a light irradiation type heating means. The infrared radiation tube made of quartz is provided on the outside of the hole, and the detection unit is arranged inside the infrared radiation tube and through the hole to face the object to be heated in the process tube. A method of measuring temperature, wherein the radiation thermometer having a detection wavelength longer than the wavelength of the output light of the light irradiation type heating means is used, and the heat treatment apparatus or the heat treatment apparatus and the temperature measurement environment are equivalent. In order to measure the temperature of the dummy heat-treated product while attaching the above-mentioned detection part to the heating device and putting the same dummy heat-treated product as the above-mentioned heat-treated product inside. A thermocouple is provided, with the emissivity set in the radiation thermometer as a parameter, at least one kind of temperature calibration data of the actual temperature measured by the thermocouple with respect to the indicated temperature of the radiation thermometer is created in advance, When heating the object to be heated in the light heating apparatus, the infrared detection unit is attached to the light heating apparatus and the emissivity of the radiation thermometer is set to the parameter value of the temperature calibration data created in advance. Is set, and the actual temperature is obtained from the indicated temperature of the radiation thermometer based on the temperature calibration data created in advance using the emissivity set in the radiation thermometer as a parameter.

Example FIG. 1 shows a light heat treatment apparatus. This light heat treatment apparatus (10) is a casing (11) having a rectangular cross section, a quartz process tube (12) having a rectangular cross section provided in the casing (11), a process tube (12) and a casing ( 11) a plurality of halogen lamps (13) provided between and one end is connected to the hole (14) formed in the central portion of the lower wall of the process tube (12) and the other end of the casing (11). A quartz infrared ray guide tube (15) extending to the lower side and a through hole (1) attached to the outer surface of the lower wall of the casing (11) and concentric with the infrared ray guide tube (15).
6) the mounting base (17) and the semiconductor wafer (19) mounted on the quartz susceptor (18) provided in the process tube (12) facing the hole (14). Infrared, hole (1
4) and a radiation thermometer having a detection unit (20) mounted on a mounting base (17) so as to be able to receive light via an infrared ray guiding tube (15).

The upper wall and the lower wall of the casing (11) are formed by a water-cooled reflection plate (21) having a cold water passage (not shown) formed therein. Casing (11) and process tube (1
The front end of 2) is open. And process tubes (12)
The front end of the process tube (12) projects forward from the front end opening of the casing (11), and the front end opening of the process tube (12) is closed by a lid (22). A gas supply port (23) and a gas discharge port (24) are provided on the rear end wall of the process tube (12).

The hole (14) of the process tube (12) is provided with a crocodile tubular lead-out pipe connection (25). The inner peripheral surface of the outlet pipe connecting portion (25) is formed into a tapered surface (25a) whose diameter becomes smaller as it goes upward. The outer peripheral surface of one end of the infrared lead-out pipe (15) is formed into a tapered surface (15a) that matches the inner peripheral tapered surface (25a) of the lead-out pipe connecting part (25). The part is fitted in the outlet pipe connecting part (25).

In the space between the upper wall of the process tube (12) and the upper wall of the casing (11) and in the space between the lower wall of the process tube (12) and the lower wall of the casing (11), A plurality of halogen lamps (13) are arranged at equal intervals and in parallel with each other, and a plurality of halogen lamps (13) are arranged in the left-right direction at equal intervals and parallel to each other.

As a radiation thermometer, the infrared detection wavelength is a halogen lamp
The output wavelength of (13) longer than 0.6 to 4.0 μm, in this example, the wavelength of 5 to 8 μm from the infrared detection wavelength is used. The detection part (20) of the radiation thermometer consists of an outer case (20a) with a circular cross section, and a cross section with a front end protruding from the inside of the outer case (20a) and containing an objective lens, an infrared detection element (not shown), etc. The inner case (20b) has a circular surface shape, and the detection section mounting screw (20c) fitted to the base of the front end of the inner case (20b) and fixed to the front surface of the outer case (20a).

As the mount (17), a water-cooled type having a cold water passage (not shown) inside is used. Through hole in mounting base (17)
(16) is a lead-out tube insertion portion (1) in which the casing (11) is opened from one end surface of the hollow and the other end of the infrared lead-out tube (15) is inserted.
6a), a screw hole (16c) in which the other end surface of the mounting base (17) is drilled and the inner diameter is approximately the same as the outer diameter of the mounting screw (20c) of the detection part (20), and the lead-out tube insertion part ( 16a) and the screw hole (16c), and the filter housing (16b) whose inner diameter is larger than the inner end of the lead-out tube insertion part (16a) and smaller than the screw hole (16c). .

An O-ring (26) is interposed between the inner peripheral surface of the lead-out tube insertion portion (16a) and the infrared lead-out tube (15). Filter storage (16
An O-ring (27), an infrared transmission filter (28), and an annular opaque Teflon filter holder (29) are sequentially fitted in b). Then, the ring-shaped filter pressing member (30) is screwed into the screw hole portion (16c), so that the infrared transmission filter (28) causes the O-ring (27) to pass through the filter storage portion (16
It is fixed while being pressed against the annular stepped portion between b) and the lead-out pipe insertion portion (16a).

As the infrared transmission filter (28), the halogen lamp (13)
The one which shields the infrared light output from the device and transmits the infrared light having the detection wavelength of the radiation thermometer, in this example, the one which transmits the infrared light having a wavelength of 5 to 8 μm is used.

The detection unit (20) is attached to the mounting base (17) by screwing the mounting screw (20c) into the screw hole (16c). In this state, the inner case (20b) of the detection unit (20)
The front end of the filter is fitted into the filter retainer pressing member (30).

The light heat treatment device (10) has the following advantages. Infrared rays incident on the detection section (20) pass through the inside of the hole (14) and the infrared emission tube (15), so the process tube (12)
It is not absorbed by or the infrared discharge tube (15). Moreover, since the detection wavelength of the radiation thermometer is 5 to 8 μm, the output light of the halogen lamp (13) (wavelength 0.6 to 4.0 μm)
Not affected by. Also, infrared transmission filter
Most of the output light from the halogen lamp (13) is blocked by (28), and most of the output light from the halogen lamp (13) that has passed through the filter (28) is as shown by the chain line in FIG. Since the light is blocked by the filter retainer (29), it is possible to prevent the output light of the halogen lamp (13) from directly entering the detector (20). Therefore, the halogen lamp (1
The output light of 3) does not damage the detection unit (20).

Furthermore, a through hole (16) communicating with the infrared lead-out pipe (15)
Is sealed by the O-rings (26) (27) and the infrared transmission filter (28), the gas inside the process tube (12) leaks to the outside through the outlet pipe (15) and the through hole (16). It is possible to prevent it. Because of this, the process tube
The heat treatment of the semiconductor wafer (19) can be performed in a state where a predetermined gas is confined in the (12) or the process tube (12) is evacuated.

FIG. 2 shows a temperature calibration device. Temperature Calibration Device (40)
The casing is provided with a casing (41) having a rectangular cross-section with an open front surface, a constant temperature bath (43) having a substantially rectangular cross-section with an open front face and being housed in the casing (41), and a constant temperature bath (43). And a quartz process tube with a rectangular cross section and an open front (44)
A frame member (45) fitted to the open end of the casing (41) and detachably attached to the casing (41), and a reflector plate (46) fitted and fixed to the frame member (45). Horizontal infrared lead-out tube (47) that penetrates the center of the reflector (46)
And an infrared guide tube attached to the outer surface of the reflector (46).
(47) and a mounting base (49) having a through hole (48) concentric with each other.

A gas supply port (50) and a discharge port (50) (only one of which is shown) are provided on the rear end wall of the process tube (44). A quartz wafer supporting member (51) supported by a reflecting plate (46) is arranged in the process tube (44). This support member (51) has a dummy wafer (52) as described later.
Mounted forward and vertically.

The reflector (46) is a reflector used in the light heat treatment device (10).
It is a water-cooled type with the same structure as (21). Infrared discharge tube (4
The inner end of 7) is substantially flush with the inner surface of the reflecting plate (46), and the outer end of the infrared ray guiding tube (47) projects outward from the reflecting plate (46). The mount (49) is the same as the mount (17) used in the light heat treatment device (10). Therefore, the through hole (48) includes the lead-out tube insertion portion (48a), the filter storage portion (48b), and the screw hole portion (48c). The outer end portion of the infrared lead-out tube (47) is inserted into the lead-out tube insertion section (48a), and an O-ring (between the inner peripheral surface of the lead-out tube insert section (48a) and the infrared lead-out tube (47) is provided. 53) is intervening. Further, the O-ring (54), the infrared transmission filter (55) and the filter retainer (56) which are the same as those used in the light heat treatment device (10) are sequentially fitted into the filter housing portion (48b) and the screw hole portion is formed. It is fixed by a filter retainer pressing member (57) screwed into (48c).

The mounting base (49) is mounted with a detection unit (20) of a radiation thermometer to be used in the light heating treatment device (10) as described later. When the detection unit (20) is attached, the distance l between the front end face of the detection unit (20) and the dummy wafer (52) is set to the attachment unit (17) of the light heat treatment device (10). The dummy wafer (5) is set so as to be equal to the distance L (see FIG. 1) between the wafer (49) and the front end face of the detection section (20) when the wafer (20) is attached.
The mounting position of 2) is set.

This temperature calibrating device (40) is provided with a thermocouple (58) for detecting the temperature of the constant temperature chamber used for controlling the temperature of the constant temperature chamber (43) and a thermocouple (59) for detecting the temperature of the dummy wafer. ing.

Before the semiconductor wafer (19) is heat-treated by the light heat treatment device (10), the calibration device (40) is used to prepare temperature calibration data as follows. First, a dummy wafer made of the same material as the semiconductor wafer (19) to be heat-treated by the light heat treatment device (10)
The wafer (52) is attached to the support member (51). Next, the mounting base
The detector (20) of the radiation thermometer used in the light heat treatment device (10) is attached to (49). Then, the emissivity ε is set to an appropriate value by the emissivity adjusting knob attached to the radiation thermometer. After that, the temperature of the constant temperature bath (43) is raised in stages, and after each stage the temperature stabilizes, the temperature indicated by the radiation thermometer and the thermocouple for detecting the dummy wafer temperature are detected.
The actual temperature measured by (59) and the actual temperature are obtained. Then, the temperature calibration data of the actual temperature measured by the thermocouple (59) for the temperature indicated by the radiation thermometer is created. Change the emissivity setting value and create data in the same way as above. Then, a plurality of temperature calibration data is created using the emissivity set in the radiation thermometer as a parameter.

FIGS. 3 and 4 show the temperature calibration data created as described above. Figure 3 shows a dummy wafer (5
FIG. 4 shows the case where silicon is used as 2) and FIG. 4 shows the case where gallium arsenide is used as the dummy wafer (52).

After the temperature calibration data is created as described above, the heat treatment of the semiconductor wafer (19) by the light heat treatment apparatus (10) is performed as follows. First, the semiconductor wafer (19) to be heat-treated is processed by the susceptor of the optical heat treatment device (10).
Set to (18). The detection unit (20) attached to the temperature calibration device (40) is attached to the attachment base (17) of the light heating treatment device (10).

Next, the emissivity when the indicated temperature of the radiation thermometer and the actual temperature correspond to approximately 1: 1 is obtained from the temperature calibration data, and the emissivity is set in the radiation thermometer. For example,
If the wafer to be heat treated is silicon, the emissivity is set to 0.7, and if the wafer to be heat treated is gallium arsenide, the emissivity is 0.65.
Set to.

After this, the halogen lamp (13) was used to
9) Heat. At this time, the temperature of the semiconductor wafer (19) is controlled by a radiation thermometer. In this case, the temperature indicated by the radiation thermometer is the actual temperature.

In the above embodiment, the emissivity of the radiation thermometer is set to the parameter value (emissivity) of the temperature calibration data in which the indicated temperature of the radiation thermometer and the actual temperature correspond to approximately 1: 1. However, the value of other temperature calibration data parameters (emissivity)
Alternatively, the emissivity of the radiation thermometer may be set. In this case, during the heat treatment of the wafer (19), based on the temperature calibration data having the emissivity set in the radiation thermometer as a parameter, the temperature indicated by the radiation thermometer
Try to find the actual temperature in (19).

Further, in general, it is difficult for a radiation thermometer to measure the temperature in a low temperature range of 400 ° C. or lower. However, the emissivity of the radiation thermometer is set to the parameter (emissivity) of the calibration data, which has a relatively small parameter (emissivity) in the created temperature calibration data, and the heat treatment of the wafer (19) is performed. When the actual temperature is calculated from the temperature indicated by the radiation thermometer based on the temperature calibration data in which the emissivity set in the radiation thermometer is used as a parameter,
It is also possible to set the temperature in the low temperature range of ℃ or less.
For example, referring to FIG. 3, when silicon is used as the wafer (19), the radiation thermometer has an emissivity of 0.3.
Is set and the actual temperature is obtained as described above during the heat treatment of the wafer (19), it becomes possible to measure the temperature in the low temperature range of 300 to 400 ° C.

In the above embodiment, the temperature calibration data is created using the temperature calibration device (40) .However, the dummy wafer (52) is placed in the light heating treatment device (10) and the thermoelectric device for measuring the dummy wafer temperature is used. A pair (59) may be provided, and the dummy wafer (52) may be heated by the heat treatment device (10) to create temperature calibration data.

EFFECTS OF THE INVENTION In the method for measuring the temperature of an object to be heat-treated in the light heat treatment apparatus according to the present invention, infrared rays from the object to be heat-treated are not absorbed by the process tube. Further, since the detection wavelength of the radiation thermometer is longer than the wavelength of the output light of the light irradiation type heating means, the influence of infrared light for heating the object to be heated to the temperature indicated by the radiation thermometer does not appear. Then, since the actual temperature is obtained based on the temperature indicated by the radiation thermometer and the temperature calibration data, accurate temperature measurement can be performed. Also, data for temperature calibration with a relatively small emissivity as a parameter is created, and the emissivity is set in the radiation thermometer, and at the time of heating the object to be heated,
When the actual temperature is obtained from the temperature indicated by the radiation thermometer based on the temperature calibration data, it becomes possible to measure a low temperature below the temperature measurement range of the radiation thermometer.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an optical heat treatment device, FIG. 2 is a vertical cross-sectional view showing a temperature calibration device, and FIG. 3 is a graph showing temperature calibration data when silicon is used as a dummy wafer. FIG. 4 is a graph showing temperature calibration data when gallium arsenide is used as a dummy wafer. (10) …… Light heating treatment device, (12) …… Process tube,
(13) …… Halogen lamp, (14) …… Hole, (15) …… Infrared discharge tube, (19) …… Semiconductor wafer, (20) …… Radiation thermometer detector, (40) …… Temperature Calibrator, (52) …… Dummy wafer, (59) …… Dummy wafer temperature measurement thermocouple.

Claims (1)

[Claims] 1. An optical heat treatment apparatus for heat-treating an object to be heat-treated placed in a quartz process tube by a light irradiation type heating means, and a quartz infrared ray is led to the outside of a hole formed in a wall of the process tube. A method of measuring the temperature of an object to be heated by a radiation thermometer, in which a detector is arranged so as to face an object to be heated in a process tube through a hole and an inside of an infrared ray guiding tube, As the radiation thermometer, the one whose detection wavelength is longer than the wavelength of the output light of the light irradiation type heating means is used, and the above-mentioned heat treatment device or the above heat treatment device is attached to the above detection unit in a heating device in which the temperature measurement environment is equivalent, A dummy heat treatment object of the same kind as the heat treatment object is put inside, and a thermocouple for measuring the temperature of the dummy heat treatment object is provided, and the radiation thermometer is provided. With the emissivity determined as a parameter, at least one kind of temperature calibration data of the actual temperature measured by the thermocouple with respect to the temperature indicated by the radiation thermometer is created in advance, and the object to be heated is subjected to the light heating treatment. When heating in the device, the infrared detection unit is attached to the optical heating device and the emissivity of the radiation thermometer is set to the value of the parameter of the temperature calibration data created in advance, and the radiation thermometer is set. A method for measuring an object to be heated in an optical heating apparatus for obtaining an actual temperature from a temperature indicated by the radiation thermometer on the basis of temperature calibration data created in advance using the generated emissivity as a parameter.