JP6976658B2 - Chuck plate and annealing equipment - Google Patents

Description

The present invention relates to a chuck plate and the annealing equipment.

A technique for measuring the temperature of the surface of a semiconductor when a semiconductor wafer is heated at high speed by a flash lamp annealing method is known (Patent Document 1). For example, the temperature of the semiconductor surface can be measured by detecting the thermal radiation light from the surface of the semiconductor wafer.

Japanese Unexamined Patent Publication No. 2008-235858

When measuring the surface temperature of a semiconductor wafer by detecting the thermal radiation light from the semiconductor wafer, it may be difficult to accurately measure the temperature due to various factors. For example, when a semiconductor wafer is held on a holding table via a chuck plate and heated, it has been found that the measurement accuracy is lowered due to the shape of the chuck plate and the holding table under the semiconductor wafer. did. An object of the present invention is to provide a chuck plate and annealing equipment capable of enhancing the accuracy of the temperature measurement by detecting thermal radiation light.

According to one aspect of the invention
A chuck plate that is placed between the object to be annealed and the holding table and has a function of attenuating the thermal radiation emitted from the object to be annealed and directed toward the holding table.
The upper surface on which the annealing target is held has a uniform region that comes into contact with the annealing target while the annealing target is held, and a non-contact surface that overlaps the annealing target but does not contact the annealing target. Including areas
A dye that absorbs thermal radiation emitted from the annealing target and directed toward the holding table is applied to at least one of the non-contact region on the upper surface where the annealing target is held and the lower surface facing the holding table. A chuck plate provided with an absorbent film containing the mixture is provided .

According to another aspect of the invention
A holding table that holds the object to be annealed,
A chuck plate arranged between the holding table and the annealing target,
A heating mechanism for heating the annealed object held on the holding table,
It has a thermal radiation photodetector that is held on the holding table and detects thermal radiation from the annealed object that is heated by the heating mechanism.
The upper surface of the chuck plate on which the annealing target is held has a uniform region in contact with the annealing target while the annealing target is held, and the annealing target overlaps with the annealing target. Including non-contact areas that do not come into contact with
At least one of the non-contact region on the upper surface where the annealing target is held and the lower surface facing the holding table is a dye that absorbs thermal radiation emitted from the annealing target and directed toward the holding table. An annealing device that has been applied is provided.

It is possible to attenuate the heat radiation that goes downward from the object to be annealed, is reflected by the holding table, passes through the chuck plate and the object to be annealed, and is directed upward. As a result, when measuring the intensity of heat radiant light, it is less affected by the chuck plate and the holding table.

FIG. 1 is a schematic view of a laser annealing device according to an embodiment. FIG. 2A is a plan view of a part of the holding table, and FIG. 2B is a plan view of a part of the chuck plate. FIG. 3 is a diagram showing a part of the distribution of the detection result of the intensity of the thermal radiation obtained when the object to be annealed is annealed using the laser annealing device according to the comparative example. FIG. 4A is a cross-sectional view of a chuck plate, a holding table, and an object to be annealed in a portion of the laser annealing device according to a comparative example in which a through hole is not provided, and FIG. 4B is a cross-sectional view of a portion in which a through hole is provided. It is sectional drawing of the chuck plate, the holding table, and the object to be annealed. FIG. 5A is a cross-sectional view of a chuck plate, a holding table, and an object to be annealed in a portion of the laser annealing apparatus according to the embodiment in which a through hole is not provided, and FIG. 5B is a cross-sectional view of a portion in which a through hole is provided. It is sectional drawing of the chuck plate, the holding table, and the object to be annealed. FIG. 6 is a diagram showing the distribution of the detection results of the intensity of the thermal radiant light acquired when annealing is performed by the laser annealing apparatus according to the embodiment. FIG. 7 shows a comparison between the temperature measurement result when annealing is performed using the laser annealing device according to the comparative example and the temperature measurement result when annealing is performed using the laser annealing device according to the embodiment. It is a graph.

A laser annealing apparatus according to an embodiment will be described with reference to FIGS. 1, 2A, and 2B.

FIG. 1 is a schematic view of a laser annealing device according to an embodiment. The holding table 13 is supported by the moving mechanism 12 in the chamber 10. The moving mechanism 12 can move the holding table 13 in a horizontal plane. The object to be annealed 30 is held on the holding table 13 via the chuck plate 14. The holding table 13 includes a vacuum chuck mechanism, and the chuck plate 14 has a plurality of through holes for exerting the action of the vacuum chuck mechanism of the holding table 13 up to the annealing target 30. The annealing target 30 is, for example, a semiconductor wafer such as a silicon wafer into which a dopant is injected. The laser annealing apparatus according to the embodiment performs, for example, activation annealing of a dopant.

The holding table 13 is made of a metal such as aluminum. For the chuck plate 14, a material harder than the material of the holding table 13, for example, ceramic or the like is used. The chuck plate 14 is arranged and used between the holding table 13 and the object to be annealed 30, for example, for the purpose of obtaining high surface accuracy.

The laser light source 20 outputs a laser beam for annealing. As the laser light source 20, for example, a laser diode having an oscillation wavelength of about 800 nm is used. The laser beam output from the laser light source 20 passes through the transmission optical system 21, the dichroic mirror 22, and the lens 23, passes through the laser transmission window 11 provided on the top plate of the chamber 10, and enters the annealing object 30. do. The dichroic mirror 22 transmits a laser beam for annealing. The transmission optical system 21 includes, for example, a beam homogenizer, a lens, a mirror, and the like. The beam homogenizer and the lens 23 shape the beam spot on the surface of the object to be annealed 30 and make the beam profile uniform.

The thermal radiation emitted from the object to be annealed 30 passes through the laser transmission window 11, is reflected by the dichroic mirror 22 via the lens 23, and is further incident on the thermal radiation detector 25 via the lens 24. .. The dichroic mirror 22 reflects thermal radiation in a wavelength range of 1 μm or more. The thermal radiant photodetector 25 measures the intensity of thermal radiant light in a specific wavelength range. The measurement result of the thermal radiation light by the thermal radiation photodetector 25 is input to the control device 40 as a voltage value.

The lens 23 and the lens 24 form an image on the surface of the object to be annealed 30 on the light receiving surface of the thermal radiation photodetector 25. Thereby, the intensity of the thermal radiant light emitted from the region of the surface of the annealed object 30 having a conjugate relationship with the light receiving surface of the thermal radiant photodetector 25 is measured. The surface area to be measured is set so as to be included inside the beam spot of the laser beam, for example.

The control device 40 controls the moving mechanism 12 to move the annealed object 30 held in the holding table 13 in the two-dimensional direction in the horizontal plane, and controls the laser light source 20 to make a pulse laser from the laser light source 20. Output the beam. Further, the control device 40 acquires the detection result of the thermal radiation photodetector 25 in synchronization with each shot of the pulsed laser beam output from the laser light source 20. The acquired detection result is stored in the storage device 41 in association with the position in the plane of the annealing target 30.

As an example, a time change in the intensity of thermal radiation can be obtained for each shot of the pulsed laser beam. The detection result stored in the storage device 41 is, for example, the peak value or the integrated value of the intensity of the thermal radiation light for each shot of the pulsed laser beam. The control device 40 outputs information on the intensity distribution of thermal radiation light in the surface of the annealed object 30 to the output device 42 as an image, a graph, or a numerical value.

FIG. 2A is a plan view of a part of the holding table 13. A hole 15 and a groove 16 are provided on the upper surface of the holding table 13. The holes 15 and the grooves 16 form, for example, a part of a holding mechanism for holding the object to be annealed 30.

FIG. 2B is a plan view of a part of the chuck plate 14. A through hole 18 is provided at a position corresponding to the hole 15 of the holding table 13 in a state where the chuck plate 14 is aligned and placed on the holding table 13. Further, a plurality of through holes 19 are distributed along the groove 16 of the holding table 13. The region where the through holes 18 and 19 are not arranged has a uniform flat surface. When the annealing target 30 is held on the upper surface of the chuck plate 14, the annealing target 30 comes into contact with the uniform flat surface, and in the region where the through holes 18 and 19 are arranged, the annealing target 30 is a chuck plate. Do not touch 14. As described above, the upper surface of the chuck plate 14 has a uniform region that contacts the annealing target 30 while the annealing target 30 is held, and a non-contact that overlaps the annealing target 30 but does not contact the annealing target 30. Includes areas.

Next, the results of an evaluation experiment using a laser annealing device according to a comparative example will be described with reference to FIGS. 3, 4A, and 4B. In the laser annealing apparatus according to the comparative example, the chuck plate 14 (FIGS. 1 and 2B) shown in FIG. 1 is made of ceramic. A silicon wafer was used as the object to be annealed 30.

FIG. 3 is a diagram showing a part of the distribution of the detection result of the intensity of the thermal radiant light acquired at the time of annealing the annealing object 30. It indicates that the dark gray area is cooler than the light gray area. The vertical striped pattern appears in FIG. 3 because the silicon wafer was scanned in the vertical direction by the laser beam.

At the location directly above the through hole 18 (FIG. 2B), the heat generated by the silicon wafer is not transferred to the outside via the chuck plate 14 (FIG. 2B), so that the temperature tends to be higher than the location in contact with the chuck plate 14. Conceivable. However, in the measurement result shown in FIG. 3, the measured value of the temperature at the position 32 corresponding to the through hole 18 (FIG. 2B) is lower than the measured value of the ambient temperature. Further, it can be seen that the measured value of the temperature is low corresponding to the region where the groove 16 (FIG. 2A) is provided.

With reference to FIGS. 4A and 4B, the reason why the measured value of the temperature at the position corresponding to the through hole 18 (FIG. 2B) is lower than the measured value of the ambient temperature will be described.

FIG. 4A is a cross-sectional view of the annealing target 30, the chuck plate 14, and the holding table 13 at a location where the through hole 18 is not provided. When the laser beam is incident on the object to be annealed 30 and heated, thermal radiation is emitted from the high temperature portion 31. The upward thermal radiation is directly incident on the thermal radiation detector 25 (FIG. 1). In the present specification, the thermal radiant light incident on the thermal radiant photodetector 25 from the hot spot 31 upward is referred to as "direct light".

The heat radiant light heading downward from the high temperature portion 31 propagates in the thickness direction of the chuck plate 14, is reflected on the surface of the holding table 13, and then passes through the chuck plate 14 and the annealing target 30 to generate heat. It is incident on the radiation detector 25. In the present specification, the heat radiant light incident on the heat radiant photodetector 25 after being reflected downward on the upper surface of the holding table 13 from the hot spot 31 is referred to as “indirect light”. As described above, in the region where the through hole 18 is not provided, the total intensity of the direct light and the indirect light is measured.

FIG. 4B is a cross-sectional view of the annealing target 30, the chuck plate 14, and the holding table 13 at the location where the through hole 18 is provided. The heat radiated light radiated downward from the high temperature portion 31 is radiated from the back surface of the chuck plate 14 to the cavity inside the through hole 18 and the hole 15. Therefore, the downward heat radiation is not reflected by the upper surface of the holding table 13 and does not enter the heat radiation detector 25.

In the region where the through hole 18 is arranged, the intensity of only the direct light is measured, and the intensity of the indirect light is not added to the measured value. As a result, the measured value of the temperature at the place where the through hole 18 is provided becomes lower than the measured value of the temperature around the portion.

In the region where the groove 16 (FIG. 2A) is provided, the temperature measurement result is low for the same reason.

Since the measurement environment differs between the location where the through hole 18 is provided and the location where the through hole 18 is not provided, accurate temperature measurement cannot be performed. In the examples described below, accurate temperature measurement can be performed.

5A and 5B are cross-sectional views of the chuck plate 14, the holding table 13, and the annealing target 30 held on the chuck plate 14 of the laser annealing apparatus according to the embodiment. FIG. 5A is a cross-sectional view of a portion where the through hole 18 is not provided, and FIG. 5B is a cross-sectional view of the portion where the through hole 18 is provided.

The chuck plate 14 used in the laser annealing apparatus according to the embodiment includes a main body 14A and an absorption film 14B coated on the upper surface thereof. As the main body 14A, for example, a plate made of ceramic is used. The absorption film 14B absorbs or attenuates light in the wavelength range of thermal radiation (for example, a wavelength of 1 μm to 3 μm). As the absorbent film 14B, for example, a film containing a black dye is used.

As shown in FIG. 5A, the heat radiated light emitted downward from the portion 31 in which the through hole 18 is not provided is absorbed or attenuated by the absorption film 14B. Further, the heat radiant light reflected by the holding table 13 and directed upward is also absorbed or attenuated by the absorption film 14B. Therefore, the intensity of the indirect light incident on the thermal radiant photodetector 25 (FIG. 1) is sufficiently lower than the intensity of the direct light.

As shown in FIG. 5B, indirect light does not enter the thermal radiation photodetector 25 (FIG. 1) even in the place where the through hole 18 is provided, as in the example shown in FIG. 4B.

As described above, in the embodiment, the intensity of only the direct light going upward from the high temperature portion 31 is measured at both the portion where the through hole 18 is provided and the portion where the through hole 18 is not provided. Can be done. Therefore, it can be said that the temperature measurement conditions are substantially the same between the portion where the through hole 18 is provided and the location where the through hole 18 is not provided. Therefore, the measurement accuracy of the temperature distribution can be improved.

FIG. 6 is a diagram showing a part of the distribution of the detection result of the intensity of the thermal radiant light acquired when annealing is performed by the laser annealing apparatus according to the embodiment. It indicates that the dark gray area is cooler than the light gray area. The measured value of the temperature at the position 32 where the through hole 18 is provided is higher than the measured value of the ambient temperature. This measurement result is consistent with the prediction that the temperature at the position where the through hole 18 is provided will be higher than the ambient temperature.

FIG. 7 shows a comparison between the temperature measurement result when annealing is performed using the laser annealing device according to the comparative example and the temperature measurement result when annealing is performed using the laser annealing device according to the embodiment. It is a graph. FIG. 7 shows the measurement results along a straight line parallel to the scanning direction (vertical direction in FIGS. 3 and 6) of the annealing target 30. The horizontal axis represents the position of the object to be annealed 30 on the surface, and the vertical axis represents the voltage detected by the thermal radiation photodetector 25 (FIG. 1) in the unit "mV". The detected voltage corresponds to the intensity of the thermal radiation. The intensity of the thermal radiation corresponds to the temperature of the object to be annealed 30. The thick solid line in the graph of FIG. 7 is the case where the chuck plate 14 according to the embodiment is used (FIG. 6), and the thin solid line is the case where the chuck plate 14 according to the comparative example without the absorption film is used (FIG. 3). The measurement result in is shown.

In the region A where the through hole 18 is provided, the two measurement results are almost the same. This is because, as shown in FIGS. 4B and 5B, the measurement environment is substantially the same for both. In the region where the through hole 18 is not provided, the measurement result (FIGS. 5A and 6) when the laser annealing device according to the embodiment is used is the measurement result when the laser annealing device according to the comparative example is used (FIG. 6). 3. Lower than FIG. 4A). Such a measurement result was obtained in the comparative example in which the indirect light also incidents on the thermal radiation photodetector 25 (FIG. 1), whereas in the embodiment, the indirect light is incident on the thermal radiation photodetector 25 (FIG. 1). This is because it is substantially not incident on FIG. 1).

The difference between the thick solid line and the thin solid line in the region where the through hole 18 is not provided corresponds to the intensity of the indirect light. From the comparison results of the graphs shown in FIG. 7, it can be seen that the intensity of the indirect light is about 10% of the intensity of the direct light.

In order to measure the temperature distribution with sufficient accuracy, it is preferable that the intensity of the indirect light is 1/100 or less of the intensity of the direct light. In order to satisfy this condition, the object to be annealed 30 travels downward from the high temperature portion 31, reflects on the upper surface of the holding table 13, and then propagates through the object 30 to be annealed and travels upward. In the meantime, it is preferable to attenuate the intensity of the thermal radiation by 90% or more.

In the above embodiment, it was shown that accurate temperature distribution can be measured even when the chuck plate 14 is provided with the through hole 18. Even when the chuck plate 14 is not provided with the through hole 18, by using the laser annealing device according to the above embodiment, the reflection characteristics of the upper surface of the holding table 13 are not affected by the in-plane variation. The effect of being able to measure an accurate temperature distribution can be obtained.

Next, a modification of the above embodiment will be described.
In the above embodiment, a film containing a black dye was used as the absorption film 14B (FIGS. 5A and 5B), but the light in the wavelength range to be detected by the thermal radiation photodetector 25 (FIG. 1). A film containing a material that absorbs or attenuates the light may be used. Further, the absorption film 14B may be provided on the lower surface instead of being provided on the upper surface of the main body 14A of the chuck plate 14, or may be provided on both the upper surface and the lower surface. In addition, the chuck plate 14 may be formed of a material having a function of attenuating thermal radiation.

The absorption film 14B may be provided on the upper surface of the holding table 13 instead of being provided on the chuck plate 14.

In the above embodiment, the object 30 to be annealed is heated by the laser beam, but it may be heated by another heating mechanism. For example, it may be heated by a flash lamp or the like.

It goes without saying that the above embodiment is an example, and partial replacement or combination of the configurations shown in the examples and modifications is possible. Similar effects and effects due to the same configuration of Examples and Modifications will not be mentioned sequentially for each Example and Modification. Furthermore, the present invention is not limited to the above-mentioned examples and modifications. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

10 Chamber 11 Laser transmission window 12 Moving mechanism 13 Holding table 14 Chuck plate 14A Chuck plate body 14B Absorption film 15 Lift pin hole 16 Groove 17 Lift pin 18 Lift pin through hole 19 Suction through hole 20 Laser light source 21 Transmission optical system 22 Dichroic mirror 23, 24 Lens 25 Thermal radiation detector 30 Annealed object 31 High temperature point 32 Position corresponding to through hole 40 Control device 41 Storage device 42 Output device

Claims (3)

A chuck plate that is placed between the object to be annealed and the holding table and has a function of attenuating the thermal radiation emitted from the object to be annealed and directed toward the holding table.
The upper surface on which the annealing target is held has a uniform region that comes into contact with the annealing target while the annealing target is held, and a non-contact surface that overlaps the annealing target but does not contact the annealing target. Including areas
A dye that absorbs thermal radiation emitted from the annealing target and directed toward the holding table is applied to at least one of the non-contact region on the upper surface where the annealing target is held and the lower surface facing the holding table. A chuck plate provided with an absorbent film containing it . A holding table that holds the object to be annealed,
A chuck plate arranged between the holding table and the annealing target,
A heating mechanism for heating the annealed object held on the holding table,
It has a thermal radiation photodetector that is held on the holding table and detects thermal radiation from the annealed object that is heated by the heating mechanism.
The upper surface of the chuck plate on which the annealing target is held has a uniform region in contact with the annealing target while the annealing target is held, and the annealing target overlaps with the annealing target. Including non-contact areas that do not come into contact with
Thermal radiant light emitted from the annealed object toward the holding table on at least one of the non-contact region of the upper surface of the chuck plate on which the annealed object is held and the lower surface facing the holding table. Annealing device coated with a dye that absorbs. The annealing device according to claim 2 , wherein the chuck plate attenuates thermal radiation in a wavelength range detected by the thermal radiation detector.

Images