JP3237557U - High speed annealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-speed annealing device applicable to a tempering process of a silicon carbide wafer. A high-speed bleaching apparatus includes a frequency conversion microwave power source system, a resonance chamber heating system, and a detection control system. The frequency conversion microwave power source system uses a solid state power amplifier, has the flexibility to sweep the frequency at high speed during heat treatment, and the resonance frequency changes due to the load effect due to the change in the temperature of the material to be ablated. Compensate to do. In order to improve energy utilization efficiency and provide sufficient microwave energy uniform region, TM010 resonance chamber configuration is adopted and tempered for 4 inch to 8 inch silicon carbide wafers. Processing can be performed. The detection and control system combines software and hardware to form an automated system with instant feedback, further improving the flexibility, stability, and reliability of the entire device. [Selection diagram] Fig. 1

Description

The present invention relates to a semiconductor device, and more particularly to a high-speed annealing device.

Silicon carbide (SiC) has a wide bandgap, high breaking electric field, high thermal conductivity, and excellent chemical inertness, making it an important semiconductor material for the manufacture of high temperature, high power waves, and high frequency devices. Ion implantation is an indispensable technique for manufacturing SiC semiconductor devices. Annealing is a necessary step after injecting the ions, removing lattice damage and activating the injected ions. In the case of silicon carbide, it is necessary to perform annealing after injecting ions at a temperature higher than 1,500 ° C.

Conventional annealing is generally performed in a ceramic furnace with resistance heating or low frequency induction heating. However, since the heating / cooling rate of the ceramic furnace is slow (20 ° C / min), it is difficult to anneal the silicon carbide at a temperature exceeding 1,500 ° C. When silicon carbide is exposed for a long time at a temperature exceeding 1,400 ° C, sublimation and redeposition of constituents (generally called step bunching) occur on the surface of the substrate, resulting in silicon carbide. The surface roughness of the wafer increases. This limits the maximum annealing temperature. Such limitations on the annealing temperature make it impossible to sufficiently activate the injected ions, resulting in higher resistance between the contact region and the channel region. At the same time, if the surface roughness is too large, the performance of the silicon carbide element is adversely affected, and one of them is that the mobility of the inversion layer is lowered and the conduction resistance of the silicon carbide MOSFET is reduced. Will be higher. Recently, several capping techniques have been proposed to suppress the above problems. However, these techniques still limit the maximum temperature and require complex processing steps. On the other hand, when silicon carbide is exposed to high temperature for a long time, a carbon-rich surface is formed, and finally a graphite surface is formed. Another bad effect of conventional annealing is that the injected boron ions cause outward and inward diffusion.

In addition to the above problems, conventional annealing also has operational drawbacks. The first problem is thermal efficiency. The main heat dissipation of the furnace body is radiation, and the amount of radiation increases in proportion to the fourth power of temperature. For this reason, widening the heating area significantly reduces the energy efficiency required for heating. In the case of a resistance heating furnace, it is common to adopt a two-tube structure, and it is possible to avoid contaminating the heater. For this reason, the area to be heated becomes wider. On the other hand, since the two-tube structure is adopted, the material to be heated is separated from the heat source. Therefore, it is necessary to set the temperature of the heater to be higher than the temperature of the material to be heated, which causes a significant decrease in efficiency. For this reason, the heat capacity of the heating system becomes very large, and the time for increasing or decreasing the temperature becomes long. As a result, the production amount decreases and the surface roughness of the material to be heated increases.

The second problem of conventional annealing concerns the waste of materials in the heating furnace. A material having a high melting point and high purity is required as a material used in a heating furnace that can withstand a temperature of 1,500 ° C. or higher. Conventionally, the materials that can be used in the silicon carbide annealing furnace are graphite and silicon carbide sintered bodies. However, since such materials are expensive, replacement is quite expensive if the furnace body is large. And the higher the temperature, the shorter the life of the furnace body, so the replacement cost is much higher than the technique of annealing a general silicon wafer.

In order to solve the problem that the heating rate of the conventional annealing technique is too slow and the surface of the silicon carbide wafer is deteriorated, it is necessary to develop a high-speed annealing technique. High-speed heat treatment is possible with halogen lamp and laser technologies, but there are still problems. For example, there are problems such as the highest achievable annealing temperature, surface melting, high residual defect density, and implant redistribution. On the other hand, microwave heating is an effective method for high-speed annealing of silicon carbide.

Silicon carbide can effectively absorb microwave energy (300 MHz to 300 GHz). A well-designed annealing system can be utilized to heat and cool silicon carbide wafers at high speeds with microwaves, and the annealing time can also be well controlled. Microwaves have the characteristic that they can be selectively heated. This is because the microwave is absorbed by the semiconductor wafer and not by the surrounding environment. Therefore, the heating rate of annealing is extremely high. Since the temperature rise of the environment around the silicon carbide wafer is limited during the high-speed annealing process, the cooling rate of the silicon carbide wafer is extremely high when the microwave source is turned off. Compared with the conventional annealing technique, when the silicon carbide is annealed by microwave, the heating rate exceeds 600 ° C / s and the temperature reaches 2,000 ° C as a result. When annealed with microwaves at 1,850 ° C for 35 seconds, the surface roughness is 2 nm. Compared to this, when annealing was performed at 1500 ° C for 15 minutes by the conventional annealing technique, the surface roughness was 6 nm. And, in terms of thin layer resistance and depth of injection element redistribute, annealing by microwave shows excellent results (SIDDARTH G. SUNDARESAN, etc; Journal of ELECTRONIC MATERIALS, Vol.36, No.4, 2007). ..

Resonant chamber coupling is a commonly used method during the process of microwave heating. The microwave heating furnace generally operates in the configuration of a fixed frequency single mode resonant chamber or a multimode resonant chamber. Since the strength of the electromagnetic field generated in the single-mode resonant chamber is higher than that in the multimode resonant chamber, it can be applied to high-speed heating. Higher heating rates, such as 10 ° C / sec to 100 ° C / sec, can be achieved with the single-mode resonant chamber, but slower with the multi-mode resonant chamber. However, according to the prior art, there are some technical hurdles when the heating rate is further much higher than 100 ° C./sec. First, during the process of heat treatment, when the physical properties of the substance to be heated change according to the change in temperature, the resonance frequency of the resonance chamber changes. The use of fixed frequency RF / microwave sources causes a mismatch with the resonant chamber. Then, the reflection of the input electromagnetic wave is greatly increased, which adversely affects the heating efficiency. Second, the resonant frequency of the resonant chamber can be mechanically adjusted, but the response time to change is slowed down and the heating rate is slowed down.

A main object of the present invention is to provide a high-speed annealing device that can be applied to a tempering process of a silicon carbide wafer.

In order to overcome the above-mentioned drawbacks of the prior art, the present invention proposes a technique and an apparatus for selectively heating at high speed using a frequency conversion microwave source, and according to the technique and the apparatus, a silicon carbide wafer. The heating rate of the annealing process can be increased, and the heating temperature can also be increased.

In the present invention, instead of the fixed frequency magnetron, a frequency conversion solid-state electronic element is used as a microwave power source. The frequency variable power source allows the selection of the highest working microwave frequency, and during the heat treatment process, the sweep frequency is flexible and compensates for the change in resonance frequency due to changes in the temperature of the material to be annealed. , Achieve the highest energy efficiency. Compared to the traveling wave tube (TWT) frequency conversion source used in conventional commercial systems, the solid-state microwave power source used in the present invention has lower manufacturing cost, smaller volume, and higher voltage system. It is not necessary and electronic control is facilitated.

The detection control system according to the present invention detects forward waves and reflected waves by using a directional coupler and a power meter, and detects the entire process of heating by microwaves by an infrared thermometer connected to a computer. , Adjust and control. High-speed heat treatment needs to be completed in a very short time, which makes manual adjustment and control difficult. Therefore, the detection control system according to the present invention constitutes an automated system having a function of immediately feeding back by combining with hardware and software. This improves the flexibility, stability and reliability of the entire device.

According to the high-speed bleaching apparatus according to the present invention, a frequency-converted microwave power source system that uses a solid-state frequency-converted microwave power source to provide a microwave having a first frequency, and a wafer pedestal and an antenna are provided. It is equipped with a resonance chamber heating system having a resonance chamber and a detection control system, and the resonance chamber of the resonance chamber heating system is provided with a chamber composed of an upper disk, a hollow cylinder and a lower disk, and the upper disk and the lower disk are , Each of which is provided on both sides of the hollow cylinder, the material to be annealed is placed on the wafer pedestal, and the microwave from the frequency conversion microwave power source system is input to the resonance chamber via the antenna. Then, in the resonance chamber, the material to be annealed is subjected to the annealing process by exciting the resonance mode, and the detection control system is the forward signal of the microwave from the frequency conversion microwave power source system and the resonance chamber. By detecting the reflected signal from the heating system, the power change is acquired by the forward signal and the reflected signal, and by detecting the temperature value of the material to be ablated, the adjustment command is given according to the temperature value and the power change. The generated and frequency-converted microwave power source system performs frequency sweep mode with tuning instructions, and immediately selects a suitable working microwave frequency with the lowest microwave reflection, replaces the first frequency and burns. It is characterized by compensating for a change in the resonance frequency of the resonance chamber due to a change in the temperature of the material to be used.

According to the high-speed bleaching apparatus according to the present invention, the frequency conversion microwave power source system includes a solid state frequency conversion microwave power source and an impedance matcher, and the impedance matcher is connected to an antenna to form a solid state frequency conversion microwave. The power source includes a microwave signal generator and a solid state power amplifier, and the microwave signal generator generates a low power microwave signal and sends it to the solid state power amplifier to send a high power microwave. It is characterized by generating.

According to the high-speed annealing device according to the present invention, the FM high-speed matching mechanism composed of the solid-state frequency conversion microwave power source and the impedance matcher reduces the microwave reflection at high speed, and the impedance matcher is fixed. Having impedance, the solid state frequency conversion microwave power source selects the best working microwave frequency suitable for the lowest microwave reflection by entering the frequency sweep mode by the tuning command of the detection control system, micro. The second frequency of the wave is characterized by compensating for a change in the resonance frequency of the resonance chamber due to a change in the temperature of the material to be ablated.

According to the high-speed incineration device according to the present invention, the detection control system further includes a pressure control system, the pressure control system is for detecting and controlling the pressure value of the resonance chamber, and the pressure control system is a pressure control system. A pressure detection unit provided in the resonance chamber is provided, the pressure detection unit is for detecting the pressure value of the resonance chamber, and the pressure control system further includes an exhaust unit and an exhaust unit which are connected to the resonance chamber, respectively. It is provided with a gas input unit, which is characterized in that the atmospheric pressure value of the resonance chamber is maintained at a planned atmospheric pressure.

According to the high speed annealing device according to the present invention, the detection control system includes a directional coupler, a power meter, an optical temperature measuring device, and a computer, and the directional coupler is a microwave from a frequency conversion microwave power source system. The forward signal and the reflected signal from the resonance chamber heating system are detected, the power meter acquires the power change by the forward signal and the reflected signal, and the computer generates the adjustment command according to the temperature value and the power change. Further, the detection control system further includes a monitor that is electrically connected to the computer, and the monitor displays the detection result of the detection control system immediately.

According to the high-speed annealing apparatus according to the present invention, the impedance matcher satisfies the matching condition because the impedance element is adjusted and the reflected microwave is extremely small before the high-power annealing process is performed. During a high-power annealing process, the physical properties of the material to be annealed change with increasing temperature, changing the resonant frequency of the microwave resonant chamber and increasing the amount of microwave reflection. .. At this time, the detection control system sends an adjustment command to the solid state frequency conversion microwave power source to adjust to the high speed frequency sweep mode to obtain the minimum reflection operating frequency and match it with the impedance of the resonant chamber heating system. It is characterized by that.

According to the high-speed annealing device according to the present invention, the antenna of the resonance chamber is composed of a metal ball and a metal rod connected to the metal ball, and the metal rod is provided on the upper disk and is a frequency conversion microwave power source. By connecting with the impedance matcher of the system, the microwave is input to the resonance chamber via the antenna.

According to the high-speed annealing apparatus according to the present invention, the upper disk and the lower disk are characterized by being parabolic disks, respectively.

According to the high-speed annealing device according to the present invention, the inner surfaces of the upper disk and the lower disk are each coated with an infrared reflective layer.

According to the high-speed annealing apparatus according to the present invention, the wafer pedestal is located in the center of the resonance chamber, and the center is the region where the microwave energy is the strongest.

According to the high-speed annealing apparatus according to the present invention, the wafer pedestal is rotatably provided in the resonance chamber, so that the uniformity of annealing of the material to be annealed is increased.

According to the high-speed annealing apparatus according to the present invention, the wafer pedestal is provided with a base and an upper lid, and the material to be annealed is placed in a chamber composed of the base and the upper lid.

According to the high-speed annealing device according to the present invention, the wafer pedestal pedestal absorbs a part of microwaves to generate heat energy, thereby conducting heat to the material to be annealed, and the wafer pedestal pedestal is microwaved. It is characterized by directly heating the material to be annealed in the chamber of the wafer cradle by allowing other parts to penetrate.

According to the high speed annealing apparatus according to the present invention, the wafer pedestal of the resonance chamber is composed of a microwave absorbing material and should be annealed by allowing more than 50% of microwaves to penetrate the material to be annealed. It is characterized by heating the material.

According to the high-speed annealing apparatus according to the present invention, the microwave absorbing material is characterized by being porous sintered silicon carbide or porous graphite having a porosity in the range of 20% to 30%.

According to the high-speed bleaching apparatus according to the present invention, the first frequency of the microwave is in the range of 433.05 to 434.79 MHz or 902 to 928 MHz, the frequency sweep range of the frequency sweep mode is ± 10 MHz, and resonance occurs. The chamber is configured in a single TM ₀₁₀ resonance mode and is characterized in that the quality coefficient (Q) of the vacant chamber of the resonance chamber exceeds 6,000.

According to the high-speed annealing device according to the present invention, the first frequency of the microwave is 434 MHz, and the diameter of the resonance chamber is 500 mm.

According to the high-speed annealing apparatus according to the present invention, the first frequency of the microwave is 500 MHz.

According to the high-speed annealing apparatus according to the present invention, the material to be annealed is silicon carbide.

According to the high-speed annealing apparatus according to the present invention, the material to be annealed is a silicon carbide wafer.

According to the high-speed annealing device according to the present invention, there are the following effects.
(1) When high-speed annealing is performed on a silicon carbide wafer using a 434 MHz microwave resonance chamber, if the single resonance TM ₀₁₀ mode is adopted, the electromagnetic field is uniform and a sufficient region is acquired, and 4 inches. Can process 8 inch wafers. The cylindrical resonant chamber has an inner surface composed of parabolas at the top and bottom. As a result, it is possible to solve the problem that a large amount of radiation loss occurs at a high temperature of the silicon carbide wafer, and it is possible to heat the silicon carbide to a temperature of 1,500 ° C to 2,000 ° C.
(2) Instead of a fixed frequency magnetron, a frequency conversion solid-state electronic element is used as a microwave power source. This allows the sweep frequency to be flexible during the heat treatment process, allowing the selection of the highest working microwave frequency and compensating for changes in the resonance frequency of the microwave resonance chamber due to changes in the temperature of the material to be tempered. be able to. At the same time, it can configure an impedance matcher and a fast match mode to meet the demands of fast annealing.
(3) The wafer pedestal of the resonance chamber can fix the silicon carbide wafer, absorb a part of the heat energy generated by the microwave, and uniformly conduct the heat to the silicon carbide wafer, and the internal heat of the silicon carbide wafer can be obtained. It is possible to prevent bursting due to stress. At the same time, it is possible to heat by allowing most microwaves to penetrate the silicon carbide wafer and prevent overheating of the edges of the silicon carbide wafer.
(4) The detection control system is combined with software and hardware to form an automated system capable of providing immediate feedback, so that the flexibility, stability and reliability of the entire device are improved.

It is a schematic diagram which shows the high-speed annealing apparatus which concerns on this invention. It is a block diagram which shows the circuit of the high-speed annealing apparatus which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The proportions of each member in the drawings of embodiments of the present invention are shown for easy understanding of the description and are not actual proportions. Further, the ratio of the dimensions of the assembly shown in the figure is for explaining each part and its structure, and of course, the present invention is not limited to this. On the other hand, for convenience of understanding, the same parts in the following embodiments will be described with the same reference numerals.

In addition, terms used throughout the specification and in the utility model claims are commonly used in this field, as disclosed herein, and as used in any particular context, unless otherwise stated. Has the meaning of. Some terms used to describe the invention are described below or elsewhere herein to provide those skilled in the art with additional guidance regarding the description of the invention.

The use of "1st", "2nd", "3rd", "4th", etc. in this article does not specifically indicate the order or sequence, but is also used to limit the present invention. It has not been. It is used only to distinguish between the components or operations described in the same terminology.

Second, when terms such as "contain", "prepare", "have", and "contain" are used in this article, they are all open terms. This means that they include, but are not limited to.

The present invention proposes a high-speed annealing device using microwaves, which can selectively heat the material to be annealed to an extremely high temperature at high speed, and requires high-speed heating and high-temperature heating in the annealing process of silicon carbide wafers. Can be satisfied with. The high-speed annealing device according to the present invention can be divided into three main parts. These are frequency conversion microwave power source systems, resonant chamber heating systems, and detection and control systems (ie, detection and control systems). The microwave is generated from a solid-state frequency-converted microwave power source, passes through an impedance matcher, and couples with a resonant chamber heating system to heat the target (ie, the material to be ablated). The detection control system regulates, detects and controls the process of heating by microwaves.

See FIGS. 1 and 2. FIG. 1 is a schematic diagram showing the configuration of the high-speed annealing device according to the present invention, and FIG. 2 is a block diagram of a circuit of the high-speed annealing device according to the present invention. The high-speed annealing device 100 according to the present invention includes a frequency conversion microwave power source system 10, a resonance chamber heating system 30, and a detection control system 50. The frequency conversion microwave power source system 10 according to the present invention utilizes the solid state frequency conversion microwave power source 12 to provide microwaves having a first frequency. The microwave frequency (that is, the first frequency) used in the present invention is, but is not limited to, 434 MHz as an example.

The resonance chamber heating system 30 includes a resonance chamber 36 having a wafer pedestal 32 and an antenna 34. The material 200 to be annealed is placed in the chamber 33 of the wafer pedestal 32 of the resonant chamber 36. Frequency-converted microwaves Microwaves from the power source system 10 enter the resonant chamber 36 via the antenna 34 of the resonant chamber heating system 30 to excite the resonant mode in the resonant chamber 36 and be ablated. 200 is annealed. The material 200 to be annealed is, for example, silicon carbide and, for example, a silicon carbide wafer. However, in the present invention, the material to be annealed is described by taking a silicon carbide material as an example, and in particular, a silicon carbide wafer is taken as an example, but the present invention is not limited to this. Any material that can be annealed can be applied to the present invention, regardless of whether high speed heating is required.

The detection control system 50 adjusts according to the change of the forward signal and the reflected signal by detecting the forward signal of the microwave from the frequency conversion microwave power source system 10 and the reflected signal from the resonance chamber heating system 30. Generate instructions immediately. The frequency conversion microwave power source system 10 enters the frequency sweep mode by this adjustment command, finds the highest working microwave frequency which is the lowest microwave reflection, and immediately sets the highest working microwave frequency which is the lowest microwave reflection. By replacing the original first frequency as the second frequency, the change in the resonance frequency from the material 200 to be annealed is compensated and the reflected wave is minimized.

Specifically, in the high-speed annealing apparatus 100 according to the present invention, the frequency conversion microwave power source system 10 includes a solid state frequency conversion microwave power source 12 and an impedance matcher (Match Box) 18. The impedance matcher 18 is connected to the above-mentioned antenna 34 (that is, a coupling antenna). The solid-state frequency conversion microwave power source 12 includes a microwave signal generator (Signal Generator) 14 and a solid-state power amplifier (SPLA) 16. The microwave signal generator 14 is for generating a low power microwave signal. The solid-state power amplifier 16 expands this low-power microwave signal to generate high-power microwaves. The frequency conversion microwave power source system 10 reduces the reflection of microwaves, increases the efficiency of energy use, and ensures the safety of the microwave power source by performing impedance matching by the impedance matcher 18. The present invention belongs to industrial use, and the usable frequency belongs to the ISM frequency band (Industrial Scientific Medical Band). According to the ITU Radio Regulations, the microwave range includes 433.05 to 434.79 MHz, 902 to 928 MHz, 2400 to 2483.5 MHz, and the like. The higher the microwave frequency, the smaller the dimensions of the resonant chamber and the smaller the energy uniform section. Since the goal of the present invention is to be able to process 8-inch wafers, TM ₀₁₀ single-mode resonance is adopted. The design of the resonant chamber is about 500 mm in diameter. At this dimension, microwaves with frequencies above 2400 MHz are difficult to adequately provide a uniform annealing region and are prone to excite other resonant modes. Therefore, the advantage of the single mode operation is lost, and it is difficult to maintain the uniformity of the microwave energy distribution. Therefore, the center frequency of the microwave used in the present invention is preferably in the range of about 433.05 to 434.79 MHz or 902 to 928 MHz, more preferably 434 MHz. The frequency sweep range in the frequency sweep mode is about ± 10 MHz. That is, the frequency sweep range increases or decreases the first frequency of the original microwave to 10 MHz, for example. This frequency sweep range is an example only, and of course, the numerical value of the frequency sweep range can be increased or decreased according to the actual need. The output power applied to the present invention can be changed according to the needs of the process and is not limited to a special range.

However, the microwave frequency applied to the present invention (ie, the first frequency) is not limited to the above range, for example, the present invention uses a microwave frequency of about 2400 to 2483.5 MHz. Further, frequencies that do not belong to the provisions of the ITU radio regulations may be used. For example, use 500 MHz, or any other frequency for which you need to apply for a license. However, it is preferable to change the design and processable size of the resonance chamber accordingly, and a person with general knowledge should know how to change the resonance chamber according to the contents disclosed in the present invention. Omitted.

Impedance matching is extremely important for achieving high speed heating. As the temperature of the material 200 to be annealed changes, the physical characteristics change, the resonance frequency of the resonance chamber changes, the reflection of microwaves decreases, and the heating performance deteriorates. Therefore, it is necessary to respond at high speed to reduce the reflection of microwaves and maintain the original heating efficiency. The above requirement can be achieved by utilizing the FM fast matching mechanism composed of the solid-state frequency conversion microwave power source 12 and the impedance matcher 18 adopted in the present invention. That is, first, the change in the resonance frequency and the impedance of the resonance chamber 36 in the process is measured and recorded, and if it corresponds to the range of the capacitance (C) and the inductance (L) when the impedance matching is achieved, it is within this range. Select an appropriate value to fix the impedance of the capacitance (C) and the inductance (L) and do not change it. When the resonance frequency and impedance of the resonance chamber 36 change in the annealing process, in the present invention, when the operating frequency of the solid state frequency conversion microwave power source 12 is changed to match the fixed impedance matching circuit described above, a high-speed match is performed. Response can be achieved. That is, the impedance matcher 18 has a fixed impedance, and the solid state frequency conversion microwave power source 12 sets the frequency sweep mode for the microwave signal by the adjustment command generated by the detection control system 50 by the reflection of the microwave. conduct. By finding the highest microwave frequency, we achieve our goal of lowering microwave reflections. In other words, the impedance matcher 18 can achieve the matching condition by adjusting the impedance element of the impedance matcher 18 before performing the high power annealing process so that the reflected microwaves are extremely small. During the high power annealing process, the physical properties of the material 200 to be annealed change with increasing temperature, changing the resonant frequency of the resonant chamber 36 and increasing the amount of microwave reflection. .. At this time, the detection control system 50 sends an adjustment command to adjust the solid state frequency conversion microwave power source 12 to the high-speed frequency sweep mode to acquire an operating frequency capable of obtaining the minimum reflection. Achieves impedance matching with the resonant chamber heating system 30. Since a person having ordinary knowledge clearly knows the detection method of the load impedance change range and the adoption of the fixed match circuit corresponding to the detection method by the contents disclosed in the present invention, the explanation is omitted.

In the resonance chamber heating system 30 of the high-speed annealing device 100 according to the present invention, the resonance chamber 36 of the resonance chamber heating system 30 includes a chamber composed of an upper disk 36a, a hollow cylinder 36b, and a lower disk 36c. The chamber is made of stainless steel. The upper disk 36a and the lower disk 36c are, for example, parabolic disks. As a result, the infrared rays emitted from the high-temperature silicon carbide wafer can be effectively reflected to the material 200 to be annealed. The upper disk 36a and the lower disk 36c are provided on both sides of the hollow cylinder 36b, respectively. The antenna 34 of the resonance chamber 36 is composed of, for example, a metal ball 34b having a diameter of about 20 mm and a metal rod 34a having a diameter of about 10 mm in contact with the metal ball 34b. The metal rod 34a is connected to the center of the top of the upper disk 36a and is connected to the impedance matcher 18 of the frequency conversion microwave power source system 10. As a result, the microwave is introduced into the resonance chamber 36 via the antenna 34, and the resonance mode is excited in the resonance chamber 36. One of the upper disk 36a and the lower disk 36c of the resonance chamber 36 is detachably connected to, for example, a hollow cylinder 36b in order to move the material 200 to be annealed in and out. As a result, the material 200 to be annealed can be taken in and out from above or below. However, the present invention is not limited to this. Of course, in the present invention, the material 200 to be annealed may be taken in and out from the side surface by adding an outlet to the hollow cylinder 36b. In other words, the present invention is not limited to this, and any technical means capable of loading and unloading the material 200 to be annealed belongs to the claims of the present application.

In order to increase energy utilization efficiency and suitable microwave energy uniform region, the present invention preferably employs a 434 MHz microwave source to generate microwaves. The resonance chamber 36 is preferably configured to be capable of generating a single TM ₀₁₀ resonance mode. Since the quality coefficient (Q) of the vacant chamber of the resonance chamber 36 exceeds 6,000, the intensity of the microwave is extremely high. The material 200 to be annealed is an example of a silicon carbide wafer, and the resonance chamber 36 has a diameter of about 500 mm and is annealed on silicon carbide wafers having various sizes (4 inches, 6 inches and 8 inches). Can be done. The silicon carbide wafer is placed in the wafer pedestal 32 in the center of the resonance chamber 36, and is located in the region where the microwave intensity is the highest. The wafer pedestal 32 is rotatably provided, for example, in the resonant chamber 36, thereby increasing the heating uniformity when annealing the material 200 to be annealed. The wafer pedestal 32 is provided on, for example, a shaft 35, and the shaft 35 is driven by, for example, a motor (not shown) to rotate. However, the wafer pedestal 32 according to the present invention is not limited to this, and may be rotated by any well-known technical means. The present invention exemplifies, but is not limited to, the resonance chamber 36 having a diameter of 500 mm. That is, the resonance chamber 36 according to the present invention may adopt another appropriate diameter or length in view of the actual need.

Silicon carbide wafers are dominated by radiant heat dissipation (proportional to the fourth power of temperature) at extremely high temperatures. At the same time, due to the planar structure of the wafer, the radiation area is large, which requires a significant reduction in radiation loss in order to improve heating efficiency and reach the heating temperature. In this embodiment, the upper and lower surfaces of the resonance chamber 36 adopt an optically polished parabolic structure (upper disk 36a and lower disk 36c), and the infrared reflective layer 37 is coated on the upper and lower surfaces of the resonance chamber 36, whereby the reflectance of infrared rays is reflected. Becomes an increasing reflector and minimizes radiation loss. For the infrared reflective layer 37, for example, a material that is metal and has a high reflectance is adopted. On the other hand, the infrared reflective layer 37 may or may not be applied to the inner surface of the hollow cylinder 36b of the resonance chamber 36. The silicon carbide wafer waiting for heating is preferably located in the resonance chamber 36 and in the wafer pedestal 32 made of a suitable microwave absorbing material. The wafer pedestal 32 is preferably located in the center of the resonance chamber 36. The center of the resonance chamber 36 is the region where the microwave energy is the highest.

The function of the wafer pedestal 32 is to fix the silicon carbide wafer (that is, the material 200 to be annealed) and to uniformly distribute the heat energy generated by absorbing microwaves to the silicon carbide wafer. It is possible to prevent bursting due to thermal stress inside the wafer. For example, the wafer pedestal 32 of the resonance chamber 36 includes a base 32a and an upper lid 32b. The top lid 32b forms the chamber 33, for example, by detachably covering the base 32a. The material 200 to be annealed is detachably positioned in the chamber 33 composed of the base 32a and the top lid 32b. On the other hand, the base 32a and / or the chamber 33 of the wafer pedestal 32 according to the present invention is not limited to a specific shape. For example, when the material 200 to be annealed is a wafer, the projected shape of the base 32a and / or the chamber 33 of the wafer pedestal 32 exhibits, for example, a circular shape. On the other hand, it is preferable that the upper lid 32b completely covers the material 200 to be annealed in the chamber 33 by the chamber 33 of the base 32a, but the present invention is not limited to this. That is, the upper lid 32b may cover a part of the chamber 33 of the base 32a and the remaining part of the surface of the material 200 to be annealed may be exposed.

In the present invention, the wafer pedestal 32 of the resonance chamber 36 absorbs, for example, a part of microwaves to generate heat energy, conducts heat to the material 200 to be ablated, and the wafer pedestal 32 is heated. By allowing the rest of the microwave to penetrate, the silicon carbide wafer placed in the chamber 33 of the wafer pedestal 32 is directly heated and reacted. The wafer pedestal 32 of the resonance chamber 36 is preferably made of a microwave absorbing material, preferably allowing more than 50% of microwaves to penetrate, heating the silicon carbide wafer. Silicon carbide, which has a sintered porosity of 20% to 30%, is a suitable material for wafer cradle, which absorbs silicon carbide at 434 MHz but has a penetration depth of microwaves. Since it exceeds 20 mm, the penetration depth is deeper than that of the porous silicon carbide produced by sintering, the function of the wafer pedestal 32 described above can be achieved, and multiple heating and cooling are performed. It does not burst even if it goes, and it has a long life. On the other hand, graphite may be used for the wafer pedestal 32.

Further, since the thickness of the silicon carbide wafer is extremely thin, when it is directly exposed to microwaves, the edge thereof tends to generate a distribution of high electric field strength, becomes overheated, and further causes tip discharge. Therefore, it is preferable that the wafer pedestal 32 covers the edge of the silicon carbide wafer waiting for annealing. This makes it possible to prevent the edge of the silicon carbide wafer from overheating.

In the present invention, the detection control system 50 further includes a barometric pressure control system 38 provided in the resonance chamber heating system 30. The air pressure control system 38 detects and controls the pressure of the resonance chamber 36 and the input gas flow rate, and holds the air pressure value of the resonance chamber 36 at, for example, a planned air pressure. The planned air pressure is about 0.1 atm to 10 atm and is set by looking at the process. The barometric pressure control system 38 includes a pressure detection unit 46 provided in the resonance chamber 36. The pressure detection unit 46 is for detecting the atmospheric pressure value of the resonance chamber 36, and is, for example, a vacuum gauge. The barometric pressure control system 38 further includes, for example, an exhaust unit 40, a pressure control unit 41, and a gas input unit 42. The exhaust unit 40 and the gas input unit 42 are connected to the resonance chamber 36, respectively. The pressure control unit 41 is a controller, and by receiving the air pressure value detected by the pressure detection unit 46, the operation of the exhaust unit 40 and / or the gas input unit 42 is controlled, and the air pressure value of the resonance chamber 36 is obtained. , Keep at the above planned pressure.

Specifically, in this embodiment, a gas such as nitrogen or argon flows into the resonance chamber 36 at a set flow rate via the gas input unit 42 and is connected to the exhaust unit 40 of the resonance chamber 36. It is discharged via the exhaust port. Before the above gas flows into the resonance chamber 36 via the gas input unit 42, first, the exhaust unit 40 bleeds the air in the resonance chamber 36 until the resonance chamber 36 reaches the above-mentioned planned pressure. A gas such as nitrogen or argon flows into the resonance chamber 36 via the gas input unit 42. As a result, the set pure gas atmosphere is realized in the resonance chamber 36. The gas input unit 42 is, for example, a gas source for the above gas, and the gas source is connected to the resonance chamber 36, for example, via a first control element (unsigned). The exhaust unit 40 is, for example, a vacuum pump, which is connected to the resonance chamber 36, for example, via a second control valve (unsigned).

In the present invention, a gas such as nitrogen or argon flows into the resonance chamber 36 via the gas input unit 42 at the above supply flow rate, and is combined with the exhaust unit 40 to form a certain exhaust flow rate from the exhaust unit 40. Then, the gas in the resonance chamber 36 is discharged. The above exhaust flow rate corresponds to the supply flow rate, so that the atmospheric pressure value of the resonance chamber 36 is maintained at the above-mentioned planned atmospheric pressure. However, the present invention is not limited to the above-mentioned technical means for maintaining the atmospheric pressure value, and all the technical means capable of maintaining the atmospheric pressure value of the resonance chamber 36 at the above-mentioned planned atmospheric pressure are used. It can be applied to the present invention. In the present invention, for example, the pressure control unit 41 is omitted, and the pressure value detected by the pressure detection unit 46 is received by the following computer 56, the supply flow rate of the gas input unit 42, and the exhaust of the exhaust unit 40. The flow rate may be controlled.

In the high-speed annealing device 100 according to the present invention, the detection control system 50 further includes a direction coupler 52 and a power meter 54. The directional coupler 52 detects the input and reflected microwave signals and sends the detected signals to the power meter 54 to detect the coupling between the microwave resonance chamber 36 and the material 200 to be tempered. It is a thing. Specifically, the directional coupler 52 is provided between the solid state power amplifier 16 and the impedance matcher 18 to detect input and reflected microwave signals. That is, the directional coupler 52 is for detecting the forward signal of the microwave from the frequency conversion microwave power source system 10 and the reflected signal from the resonance chamber heating system 30. Next, the directional coupler 52 sends the detected signal to the power meter 54 to immediately detect a change in coupling (for example, a power change) between the microwave resonance chamber 36 and the material 200 to be annealed. It is a thing. As a result, the computer 56 receives the power change data and immediately generates an adjustment instruction based on the power change data to control the operation of the frequency conversion microwave power source system 10.

The detection control system 50 further includes an optical temperature measuring device (Optical Pyrometer) 58. The optical temperature measuring device 58 is for immediately detecting the temperature value of the material 200 to be annealed, and is, for example, an infrared high temperature thermometer. Further, the computer 56 is electrically connected to the optical temperature measuring device 58, so that an adjustment command is generated by the temperature value detected by the optical temperature measuring device 58 and the power change described above, and the micro is generated. Controls the energy of the wave input. Thereby, it is possible to control to reach the required heating temperature and cooling temperature. In the present invention, the emissivity of the silicon carbide material detected using the black body radiation source is 0.74, and when this emissivity value is input to the optical temperature measuring device 58, it is disclosed in the present invention. All temperatures of the technology can be measured. On the other hand, the detection control system 50 further includes, for example, a monitor 60 electrically connected to the computer 56. The monitor 60 can instantly display the detection results of each component of the detection control system 50, for example, all microwave and temperature data are input to a computer for recording and processing to monitor 60. It can be displayed immediately.

According to the high-speed annealing device according to the present invention, there are the following effects.
(1) When high-speed annealing is performed on a silicon carbide wafer using a 434 MHz microwave resonance chamber, if the single resonance TM ₀₁₀ mode is adopted, the electromagnetic field is uniform and a sufficient region is acquired, and 4 inches. Can process 8 inch wafers. The cylindrical resonant chamber has an inner surface composed of parabolas at the top and bottom. As a result, it is possible to solve the problem that a large amount of radiation loss occurs at a high temperature of the silicon carbide wafer, and it is possible to heat the silicon carbide to a temperature of 1,500 ° C to 2,000 ° C.
(2) Instead of a fixed frequency magnetron, a frequency conversion solid-state electronic element is used as a microwave power source. This allows the sweep frequency to be flexible during the heat treatment process, allowing the selection of the highest working microwave frequency and compensating for changes in the resonance frequency of the microwave resonance chamber due to changes in the temperature of the material to be tempered. be able to. At the same time, it can configure an impedance matcher and a fast match mode to meet the demands of fast annealing.
(3) The wafer pedestal of the resonance chamber can fix the silicon carbide wafer, absorb a part of the heat energy generated by the microwave, and uniformly conduct the heat to the silicon carbide wafer, and the internal heat of the silicon carbide wafer can be obtained. It is possible to prevent bursting due to stress. At the same time, it is possible to heat by allowing most microwaves to penetrate the silicon carbide wafer and prevent overheating of the edges of the silicon carbide wafer.
(4) The detection control system is combined with software and hardware to form an automated system capable of providing immediate feedback, so that the flexibility, stability and reliability of the entire device are improved.

10 Frequency conversion microwave power source system 12 Solid state frequency conversion microwave power source 14 Microwave signal generator 16 Solid state power amplifier 18 Impedance matcher 30 Resonance chamber heating system 32 Wafer cradle heating system 32 Wafer pedestal 32a Base 32b Top lid 33 Chamber 34 Antenna 34a Metal Rod 34b Metal ball 35 Shaft 36 Resonance chamber 36a Upper disk 36b Hollow cylinder 36c Lower disk 37 Infrared reflective layer 38 Pressure control system 40 Exhaust unit 41 Pressure control unit 42 Gas input unit 46 Pressure detection unit 50 Detection control system 52 Directional coupler 54 Power Total 56 Computer 58 Optical temperature measuring device 60 Monitor 100 High-speed ablation device 200 Material to be ablated

Claims (19)

A frequency-converted microwave power source system that utilizes a solid-state frequency-converted microwave power source to provide microwaves with a first frequency.
A resonant chamber heating system with a resonant chamber with a wafer pedestal and an antenna,
Detection control system and
Equipped with
The resonant chamber of the resonant chamber heating system comprises a chamber composed of an upper disk, a hollow cylinder and a lower disk.
The upper disk and the lower disk are provided on both sides of the hollow cylinder, respectively.
The material to be annealed is placed on the wafer pedestal, and the microwave from the frequency-converted microwave power source system is input to the resonant chamber via the antenna and in the resonant chamber. By exciting the resonance mode, the material to be annealed is subjected to an annealing treatment.
The detection control system detects the forward signal of the microwave from the frequency conversion microwave power source system and the reflected signal from the resonance chamber heating system, so that the power is changed by the forward signal and the reflected signal. And by detecting the temperature value of the material to be annealed, an adjustment command is generated according to the temperature value and the power change.
The frequency conversion microwave power source system performs a frequency sweep mode by the adjustment command and immediately selects a suitable working microwave frequency with the lowest microwave reflection to replace the first frequency. It is characterized by compensating for a change in the resonance frequency of the resonance chamber due to a change in the temperature of the material to be ablated.
High-speed annealing device. The frequency-converted microwave power source system comprises a solid-state frequency-converted microwave power source and an impedance matcher, the impedance matcher is coupled to the antenna, and the solid-state frequency-converted microwave power source is micro. A wave signal generator and a solid state power amplifier are provided, and the microwave signal generator generates a low power microwave signal and sends it to the solid state power amplifier to generate the high power microwave. The high-speed incineration device according to claim 1, wherein the high-speed microwave apparatus is used. The FM high-speed matching mechanism composed of the solid-state frequency-converted microwave power source and the impedance matcher rapidly reduces the reflection of the microwave, and the impedance matcher has a fixed impedance and is described. The solid-state frequency-converted microwave power source selects the preferred highest working microwave frequency at the lowest microwave reflection by entering the frequency sweep mode by the tuning command of the detection control system. The high-speed annealing device according to claim 2, wherein the second frequency of the wave compensates for a change in the resonance frequency of the resonance chamber due to a change in the temperature of the material to be annealed. The detection control system further includes a barometric pressure control system.
The air pressure control system is for detecting and controlling the air pressure value of the resonance chamber.
The barometric pressure control system comprises a pressure sensing unit provided in the resonant chamber.
The pressure detection unit is for detecting the atmospheric pressure value in the resonance chamber.
The atmospheric pressure control system further includes an exhaust unit and a gas input unit, which are connected to the resonance chamber, respectively, whereby the atmospheric pressure value of the resonance chamber is maintained at a predetermined atmospheric pressure. , The high-speed annealing apparatus according to claim 1. The detection control system includes a directional coupler, a power meter, an optical temperature measuring device, and a computer.
The directional coupler detects the forward signal of the microwave from the frequency conversion microwave power source system and the reflected signal from the resonant chamber heating system.
The power meter acquires the power change by the forward signal and the reflected signal, and obtains the power change.
The computer generates the adjustment command in response to the temperature value and the power change, and the detection control system further includes a monitor electrically connected to the computer, and the detection control system by the monitor. The high-speed annealing device according to claim 1, wherein the detection result of the above is displayed immediately. The antenna of the resonance chamber is composed of a metal ball and a metal rod connected to the metal ball, and the metal rod is provided on the upper disk and is an impedance matcher of the frequency conversion microwave power source system. The high-speed annealing device according to claim 1, wherein the microwave is input to the resonance chamber via the antenna. The high-speed annealing device according to claim 6, wherein the upper disk and the lower disk are parabolic disks, respectively. The high-speed annealing device according to claim 6, wherein an infrared reflective layer is coated on the inner surfaces of the upper disk and the lower disk, respectively. The high-speed annealing device according to claim 1, wherein the wafer pedestal is located at the center of the resonance chamber, and the center is a region where the microwave energy is the strongest. The high-speed annealing device according to claim 1, wherein the wafer pedestal is rotatably provided in the resonance chamber to increase the uniformity of annealing of the material to be annealed. The high-speed annealing apparatus according to claim 10, wherein the wafer pedestal includes a base and an upper lid, and the material to be annealed is placed in a chamber composed of the base and the upper lid. .. The wafer pedestal absorbs a part of the microwave to generate heat energy, so that the wafer pedestal is conducted to the material to be annealed and heated.
11. The wafer pedestal is characterized in that it directly heats the material to be annealed in the chamber of the wafer pedestal by allowing other parts of the microwave to penetrate. High-speed annealing device described in. The wafer pedestal of the resonance chamber is composed of a microwave absorbing material and heats the material to be annealed by allowing more than 50% of the microwave to penetrate the material to be annealed. 12. The high-speed annealing apparatus according to claim 12. The high-speed annealing apparatus according to claim 13, wherein the microwave absorbing material is porous sintered silicon carbide or porous graphite having a porosity in the range of 20% to 30%. The first frequency of the microwave falls in the range of 433.05 to 434.79 MHz, or 902 to 928 MHz, the frequency sweep range of the frequency sweep mode is ± 10 MHz, and the resonance chamber is a single TM ₀₁₀ . The high-speed annealing device according to claim 1, wherein the resonance mode is configured, and the quality coefficient (Q) of the vacant chamber of the resonance chamber exceeds 6,000. The high-speed annealing device according to claim 1, wherein the first frequency of the microwave is 434 MHz, and the diameter of the resonance chamber is 500 mm. The high-speed annealing device according to claim 1, wherein the first frequency of the microwave is 500 MHz. The high-speed annealing apparatus according to claim 1, wherein the material to be annealed is silicon carbide. The high-speed annealing apparatus according to claim 1, wherein the material to be annealed is a silicon carbide wafer.

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