JP5037988B2 - Method for manufacturing SiC semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a SiC semiconductor device.

SiC (Silicon Carbide) is superior in withstand voltage and heat resistance because it has a larger band gap than Si (Silicon), and is particularly used in devices capable of handling high voltages.
In general, when a diffusion region of a predetermined conductivity type is formed on a SiC substrate, as in the case of the Si substrate, a step of implanting ions as impurities into the SiC substrate and an activation for activating the impurities An annealing process is performed. Then, after the activation annealing step, a step of cooling the SiC substrate by a gas flow in a furnace is performed (for example, Patent Document 1).
JP 2002-261101 A

The activation annealing process for the SiC substrate usually takes at least 2 hours or more after the activation annealing process to cool to room temperature that does not cause burns even if touched by the operator after the activation annealing process. (See, for example, 200 in FIG. 2).
Therefore, shortening the cooling time after the activation annealing step has been a problem to be solved in manufacturing the SiC semiconductor device (device).
In view of the above problems, the present invention intends to provide a method for manufacturing a SiC semiconductor device.

A method for manufacturing a SiC semiconductor device according to an aspect of the present invention includes a first step of preparing a SiC substrate, a second step of implanting ions into the SiC substrate, and heating the SiC substrate with an annealing apparatus. The furnace includes a third step of heating at about 1500 ° C. to about 2000 ° C., and a fourth step of cooling the SiC substrate to room temperature at a rate of about 500 ° C./min to about 2000 ° C./min.
A method for manufacturing a SiC semiconductor device according to another aspect of the present invention includes a first step of preparing a SiC substrate, a second step of implanting ions into the SiC substrate, and heating the SiC substrate with an annealing device. A third step of heating at about 1500 ° C. to about 2000 ° C. in the furnace; and after cooling the SiC substrate in the furnace to a temperature of about 300 ° C. to about 1000 ° C., the SiC substrate is about 500 ° C./min Or a fourth step of cooling to room temperature at a rate of about 2000 ° C./min.

In the method for manufacturing a SiC semiconductor device of the present invention, the SiC substrate is rapidly cooled with pure water or the like after the activation annealing step, so that the cooling time after the activation annealing step can be shortened.
Moreover, since it becomes possible to perform cooling inside the annealing apparatus, it is possible to obtain an excellent effect that the worker does not touch the high-temperature SiC substrate at all and the safety of the worker can be ensured.

Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of a method for manufacturing a SiC semiconductor device embodying the present invention.
FIG. 1 shows a semiconductor device manufacturing apparatus 100 according to an embodiment of the present invention. The semiconductor manufacturing apparatus 100 includes a heat treatment chamber (heating furnace for annealing apparatus) 101 and a load lock chamber 102. Heat treatment chamber 101 is used to heat-treat the SiC substrate. The load lock chamber 102 is used to block the atmosphere. This is to prevent the heat insulating material and carbon of the susceptor 105 from being oxidized and burned by the atmosphere.
The semiconductor element manufacturing apparatus 100 further includes a gate valve 103 between the heat treatment chamber 101 and the load lock chamber 102. By opening and closing the gate valve 103, the heat treatment chamber 101 and the load lock chamber 102 can be partitioned.
The semiconductor element manufacturing apparatus 100 further includes a transport unit such as a sample transport bar 104. The sample transport rod 104 includes a susceptor 105 on which an SiC substrate is placed, and the susceptor 105 can be moved between the heat treatment chamber 101 and the liquid tank (tank) 106 of the load lock chamber 102.

The load lock chamber 102 includes a liquid tank 106. Moreover, although not shown in figure, it has the introductory water channel which introduce | transduces a pure water into the heating furnace from the liquid tank 106, and the outlet water channel which guide | induces a pure water from a heating furnace. The liquid tank 106 is filled with a chemically stable liquid such as pure water. In this case, pure water has a certain degree of purity. The liquid tank 106 may contain liquid argon (Ar) instead of pure water.
The load lock chamber 102 further includes a sample exchange port 107 so that the sample on the susceptor 105 can be exchanged. The load lock chamber 102 further includes a gas introduction port 108 and an exhaust port 109. The gas is introduced from the gas inlet 108 and discharged to the exhaust outlet 109.
The heat treatment chamber 101 includes an RF (Radio Frequency) coil 110, a gas introduction port 111, and an exhaust port 112. The RF coil 110 is used to heat the SiC substrate, and other heating means can be applied.
Gas (mainly inert gas) is introduced from the gas introduction port and discharged to the exhaust port. This is to prevent the SiC substrate from being exposed to oxygen and being oxidized.

FIG. 2 is an example of a temperature profile for implementing the semiconductor manufacturing apparatus shown in FIG.
First, a method of manufacturing an SiC semiconductor device that implements a temperature profile as indicated by 201 in FIG. 2 will be described.
The ion-implanted SiC substrate is attached to the susceptor 105 and moved to the heat treatment chamber 101. The heat treatment chamber 101 and the load lock chamber 102 are evacuated to remove the atmosphere, and then argon gas is introduced into both chambers (the heat treatment chamber 101 and the load lock chamber 102) to atmospheric pressure. The gate valve 103 is closed and an activation annealing process is performed. In this embodiment, the SiC substrate is heated to a predetermined temperature in a heat treatment chamber (heating furnace of an annealing apparatus) 101. Preferably, it is heated to about 1500 ° C to about 2000 ° C. Thereby, impurities in the SiC substrate can be activated.

Next, a step of cooling the SiC substrate to room temperature at a predetermined rate is performed. Preferably, it is cooled to room temperature at a rate of about 500 ° C./min to about 2000 ° C./min. In this embodiment, the gate valve 103 is opened, the susceptor 105 is moved downward by the sample transport rod 104, and the susceptor 105 on which the SiC substrate is placed is immersed in pure water in the liquid tank 106. As a result, the temperature of the susceptor 105 rapidly decreases to about 100 ° C. as indicated by 201 in FIG. Since the boiling point of pure water is 100 ° C., the water temperature does not rise above the boiling point. In the present embodiment, one of the reasons for using pure water having a certain degree of purity is to exclude the contribution of impurities to the SiC substrate when the impurities are contained in water.
In the present embodiment, an example of cooling to room temperature at a rate of about 500 ° C./min to about 2000 ° C./min is shown, but an embodiment in which cooling to room temperature at a slower rate than the above is also applicable to the present invention. Applicable.

As another aspect, when liquid argon is contained in the liquid tank 106, when the susceptor 105 on which the SiC substrate is placed is immersed in the liquid argon in the liquid tank 106, the temperature of the susceptor 106 is reduced to -183 ° C. Go down. Thereafter, by removing the susceptor 105 from the liquid tank 106 containing liquid argon, the temperature of the susceptor rises to room temperature in the load lock chamber.
Further, in the process of immersing the susceptor 105 in the liquid argon in the liquid tank 106, while the temperature of the susceptor 105 is decreasing, for example, the temperature of the susceptor is a predetermined temperature (for example, around 0 ° C. or load lock). It is also possible to use a configuration in which the susceptor 105 is taken out from the liquid tank 106 by detecting that the temperature has dropped to around the room temperature of the chamber.
In the manufacturing method of the SiC semiconductor device of the present embodiment, the SiC substrate is rapidly cooled with pure water after the annealing step, so that the cooling time after the activation annealing step can be shortened.

As another embodiment of the present invention, a method of manufacturing a SiC semiconductor device that implements a temperature profile as shown at 202 in FIG. 2 using the semiconductor manufacturing device of FIG. 1 will be described.
SiC is attached to the susceptor 105, and the SiC substrate is heated to a predetermined temperature in a heat treatment chamber (annealing device heating furnace) 101, preferably about 1500 ° C. to about 2000 ° C. Up to this point, the process is the same as in the previous embodiment.
In the present embodiment, after heating, cooling is performed with a gas flow in the furnace, and waiting for the temperature of the SiC substrate to drop to a predetermined temperature. Preferably, waiting for the temperature of the SiC substrate to drop to about 300 ° C to about 1000 ° C. In this embodiment, as shown at 202 in FIG. 2, the case where the temperature of the SiC substrate is cooled to about 1000 ° C. by the gas flow is shown. This temperature is determined in relation to the required cooling time, and a temperature profile that waits to drop to a temperature lower (or higher) than about 1000 ° C. may be used. Thereafter, the SiC substrate is immersed in the cooling bath 106, and the SiC substrate is cooled to room temperature at a predetermined rate, preferably at a rate of about 500 ° C./min to about 2000 ° C./min.
In the present embodiment, the SiC substrate is not rapidly cooled immediately after being heated, but the SiC substrate is slowly cooled to a predetermined temperature by a gas flow or the like, and then cooled rapidly to produce SiC. The present embodiment can be applied to the case where the influence of the rapid cooling process on the SiC substrate and the like is taken into consideration.
The subsequent steps are the same as those in the previous embodiment.

  While the above description has been made with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the spirit of the invention and the scope of the appended claims.

FIG. 1 is a diagram showing a configuration of a semiconductor manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between the cooling time and the substrate temperature in the cooling process of the semiconductor manufacturing apparatus according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Semiconductor device manufacturing apparatus 101 Heat processing chamber 102 Load lock chamber 103 Gate valve 104 Sample conveyance rod 105 Susceptor 106 Liquid tank 107 Sample exchange port 108, 111 Gas introduction port 109, 112 Exhaust port 110 RF coil

Claims (4)

A first step of preparing a SiC substrate;
A second step of implanting ions into the SiC substrate;
The ion implantation previously SiC substrate mounted on a susceptor, in a heating furnace of the annealing apparatus, at 1500 ° C. to 2000 ° C., and a third step of heating each of the susceptor the SiC substrate,
A fourth step of cooling the SiC substrate together with the susceptor to a normal temperature at a rate of 500 ° C./min to 2000 ° C./min;
Only including,
The fourth step is a method of manufacturing an SiC semiconductor device, wherein the SiC substrate together with the susceptor is immersed in pure water stored in a tank provided in the annealing device and cooled . A first step of preparing a SiC substrate;
A second step of implanting ions into the SiC substrate;
The ion implantation previously SiC substrate mounted on a susceptor, in a heating furnace of the annealing apparatus, at 1500 ° C. to 2000 ° C., and a third step of heating each of the susceptor the SiC substrate,
After the SiC substrate is cooled in a furnace to a temperature of 300 ° C. to 1000 ° C., the SiC substrate is cooled together with the susceptor to a normal temperature at a rate of 500 ° C./min to 2000 ° C./min. A fourth step of
Only including,
The fourth step is a method of manufacturing an SiC semiconductor device, wherein the SiC substrate together with the susceptor is immersed in pure water stored in a tank provided in the annealing device and cooled . 3. The method of manufacturing an SiC semiconductor device according to claim 1, wherein the annealing apparatus includes a transport unit that unloads the SiC substrate from the heating furnace and loads the SiC substrate into the tank. 3. The method of manufacturing an SiC semiconductor device according to claim 1, wherein the annealing apparatus has an introduction water channel for introducing the pure water from the tank into the heating furnace.