JP2020181849A - Manufacturing method of semiconductor device and ion implantation device - Google Patents

Abstract

To provide a technique of shortening a time required for manufacturing a semiconductor device in a technique of forming a diffusion region while heating a silicon carbide substrate.SOLUTION: A manufacturing method of a semiconductor device includes an ion implantation step of implanting ions into an ion implantation region 42 of a silicon carbide substrate 40 while irradiating the ion implantation region 42 with laser light to heat the ion implantation region 42 of the silicon carbide substrate 40.SELECTED DRAWING: Figure 2

Description

The techniques disclosed herein relate to methods of manufacturing semiconductor devices. The techniques disclosed herein also relate to ion implantation devices used in methods of manufacturing semiconductor devices.

Patent Document 1 discloses a technique for ion-implanting ions into an ion-implanted region of a silicon carbide substrate. In this technique, ion implantation is performed in a state where the silicon carbide substrate is heated to a high temperature. It is said that this makes it possible to suppress the occurrence of crystal defects during ion implantation and suppress the deterioration of the electrical characteristics of the semiconductor device.

Japanese Unexamined Patent Publication No. 2014-39057

In the technique of Patent Document 1, the temperature of the silicon carbide substrate is controlled by using a heater mounted on a stage holding the silicon carbide substrate. In this technique, since the temperature of the entire silicon carbide substrate is controlled, there is a problem that the heating time before ion implantation and the cooling time after ion implantation are long, and the time required for manufacturing the semiconductor device is long. As described above, in the technique of forming the diffusion region in the state where the silicon carbide substrate is heated to a high temperature, a technique of shortening the time required for manufacturing the semiconductor device is required.

In the method for manufacturing a semiconductor device disclosed in the present specification, ions are implanted into the ion-implanted region while irradiating the ion-implanted region of the silicon carbide substrate with laser light to heat the ion-implanted region of the silicon carbide substrate. An ion implantation step, which is to be performed, can be provided. In this manufacturing method, a part of the silicon carbide substrate, that is, a range including the ion-implanted region of the silicon carbide substrate is selectively heated by irradiating the laser beam, so that it is necessary to heat the ion-implanted region. The time and the time required for cooling after ion implantation are short. Therefore, in this manufacturing method, the time required for manufacturing the semiconductor device can be shortened. Further, in this production method, since the ion implantation is performed while heating the ion implantation region with the laser beam, the ion-implanted ions can be diffused and activated at the same time. Therefore, if necessary, the annealing step for diffusing and activating the ion-implanted ions can be omitted as a subsequent step after the ion implantation. In this respect as well, this manufacturing method can shorten the time required for manufacturing the semiconductor device.

In the above manufacturing method, the laser beam may be applied to the surface of the silicon carbide substrate from an oblique direction. In this manufacturing method, laser light irradiation can be performed without interfering with ion implantation that is irradiated from the orthogonal direction to the surface of the silicon carbide substrate.

The manufacturing method may further include a heat treatment step of irradiating the ion-implanted region of the silicon carbide substrate with the laser beam to heat the silicon carbide substrate before the ion implantation step. By carrying out the ion implantation step after the temperature of the silicon carbide substrate reaches a predetermined temperature, it is possible to satisfactorily diffuse and activate the ions to be ion-implanted.

The manufacturing method may further include a film forming step of forming an external diffusion prevention film on the surface of the silicon carbide substrate before the heat treatment step. The outer diffusion prevention film is made of a material that prevents the silicon constituting the silicon carbide substrate from diffusing outward from the surface of the silicon carbide substrate. According to this manufacturing method, in the heat treatment step and the ion implantation step, the diffusion of silicon from the surface of the silicon carbide substrate to the outside is suppressed, and the surface roughness of the silicon carbide substrate is suppressed.

The ion implantation apparatus disclosed in the present specification can include a laser beam irradiating means configured to be capable of irradiating a laser beam to an object to be processed. Since such an ion implantation device can simultaneously perform ion implantation and laser light irradiation, it can be used in the method for manufacturing the semiconductor device.

The outline of the structure of the ion implantation apparatus of this embodiment is shown. The manufacturing flow which forms the diffusion region in the surface layer part of the silicon carbide substrate is shown. A cross-sectional view of the silicon carbide substrate in the process of forming a diffusion region on the surface layer portion of the silicon carbide substrate is schematically shown. A cross-sectional view of the silicon carbide substrate in the process of forming a diffusion region on the surface layer portion of the silicon carbide substrate is schematically shown. A cross-sectional view of the silicon carbide substrate in the process of forming a diffusion region on the surface layer portion of the silicon carbide substrate is schematically shown.

FIG. 1 schematically shows the configuration of an ion implantation device 1 used in manufacturing a silicon carbide semiconductor device. The ion implantation device 1 is a device for implanting ions into the ion implantation region of the surface layer portion of the silicon carbide substrate 40 held in the stage 30, and includes an ion implantation means 10 and a laser irradiation means 20. The ion implantation region is an n-type or p-type diffusion that constitutes an element mounted on the silicon carbide substrate 40, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), a diode, or the like. A region in which an n-type or p-type dopant is ion-implanted to form a region.

The ion implantation means 10 includes an ion source 12, an extraction electrode 14, a mass spectrometer 16, and an analysis slit 18. The various types of ion beams drawn from the ion source 12 through the extraction electrode 14 are separated by the mass spectrometer 16. The analysis slit 18 allows only the ion species necessary for ion implantation to pass through the ion beam separated by the mass spectrometer 16. The ion beam that has passed through the analysis slit 18 is irradiated to the ion implantation region of the surface layer portion of the silicon carbide substrate 40.

The laser light irradiating means 20 includes a laser light oscillator 22, a condenser lens 24, and a rectangular fiber 26. The laser light oscillator 22 is configured to oscillate laser light having a specific wavelength that does not pass through the silicon carbide substrate 40. For example, the laser light oscillator 22 is configured to oscillate infrared laser light using an LD-pumped solid-state laser. The wavelength of the laser light oscillated from the laser light oscillator 22 is appropriately adjusted based on the depth of the ion implantation region and the like. The condenser lens 24 is configured to collect the laser light oscillated from the laser light oscillator 22 and guide it to the incident end of the rectangular fiber 26. The rectangular fiber 26 is configured to emit the laser beam incident from the incident end from the emitted end and irradiate the ion implantation region of the surface layer portion of the silicon carbide substrate 40.

The exit end of the rectangular fiber 26 is arranged obliquely above the ion implantation region of the surface layer portion of the silicon carbide substrate 40. As a result, the laser beam emitted from the exit end of the rectangular fiber 26 is irradiated from the surface of the silicon carbide substrate 40 from an oblique direction toward the ion implantation region. As described above, the optical axis of the laser beam emitted from the rectangular fiber 26 is inclined with respect to the orbital axis of the ion beam passing through the analysis slit 18 (the axis along the orthogonal direction with respect to the surface of the silicon carbide substrate 40). doing. As a result, the ion implantation device 1 is configured so that laser light irradiation and ion implantation can be performed at the same time. Further, the exit end of the rectangular fiber 26 is configured so that the ion implantation region of the surface layer portion of the silicon carbide substrate 40 can be scanned. As a result, the ion implantation device 1 is configured to be able to selectively heat a range including the ion implantation region of the surface layer portion of the silicon carbide substrate 40.

A method of forming a diffusion region on the surface of the silicon carbide substrate 40 by using the ion implantation apparatus 1 of FIG. 1 will be described with reference to FIGS. 2 to 5. FIG. 2 shows a manufacturing flow. 3 to 5 schematically show a cross-sectional view of a silicon carbide substrate during a manufacturing process.

First, as shown in FIG. 3, the stage 30 is used to hold the silicon carbide substrate 40 to be processed, and the silicon carbide substrate 40 is prepared in the ion implantation apparatus 1 (step S1 in FIG. 2). An external diffusion prevention film 52 is formed on the surface of the silicon carbide substrate 40. The outer diffusion prevention film 52 is made of a material that prevents the silicon constituting the silicon carbide substrate 40 from diffusing outward from the surface of the silicon carbide substrate 40. As an example, as the outer diffusion prevention film 52, a carbon film, a silicon oxide film, or a resist is used. The outer diffusion prevention film 52 can suppress surface roughness caused by diffusion of silicon outward from the surface of the silicon carbide substrate 40 in the heat treatment step and the ion implantation step described later. Further, a mask layer 54 is formed on the surface of the outer diffusion prevention film 52. An opening is formed in the mask layer 54 corresponding to the ion implantation region 42 of the surface layer portion of the silicon carbide substrate 40. As an example, a silicon oxide film is used as the material of the mask layer 54. The mask layer 54 may be formed on the surface of the silicon carbide substrate 40 without forming the outer diffusion prevention film 52.

Next, as shown in FIG. 4, the ion implantation region 42 of the surface layer portion of the silicon carbide substrate 40 is irradiated with laser light to heat the ion implantation region 42 (step S2 in FIG. 2). In this heat treatment step, a laser beam is irradiated to selectively heat a part of the silicon carbide substrate 40, that is, a range including the ion implantation region 42. This heat treatment step is carried out until the temperature of the ion implantation region 42 reaches the melting temperature of silicon carbide.

Next, as shown in FIG. 5, ions are implanted into the ion implantation region 42 of the surface layer portion of the silicon carbide substrate 40 while continuing the laser irradiation (step S3 in FIG. 2). In this ion implantation step, the irradiation of the laser beam is continued, so that the temperature of the ion implantation region 42 is maintained at a high temperature. Therefore, in this ion implantation step, the occurrence of crystal defects during ion implantation is suppressed, and the deterioration of the electrical characteristics of the semiconductor device is suppressed. Next, the laser beam irradiation and ion implantation are stopped, and the ion implantation step is completed (step S4 in FIG. 2).

In the above manufacturing method, a part of the silicon carbide substrate 40, that is, a range including the ion implantation region 42 is selectively heated by irradiating the laser beam. Therefore, the time required for heating the ion implantation region 42 and the time required for cooling after ion implantation can be shortened, and the time required for manufacturing the semiconductor device can be shortened.

Further, in the ion implantation step of the above-mentioned manufacturing method, ion implantation is performed while continuing the irradiation of the laser beam. In particular, in the ion implantation step of the above manufacturing method, the temperature of the ion implantation region 42 is maintained above the melting temperature of silicon carbide by high-power laser irradiation, so that the ion-implanted ions are diffused and activated. It can proceed at the same time. Therefore, in the above manufacturing method, the annealing step for diffusing and activating the ion-implanted ions as a subsequent step after the ion implantation can be omitted. As a result, the time required for manufacturing the semiconductor device can be shortened.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

1: Ion implantation device 10: Ion implantation means 12: Ion source 14: Extraction electrode 16: Mass spectrometer 18: Analysis slit 20: Laser light irradiation means 22: Laser light oscillator 24: Condensing lens 26: Rectangular fiber 30: Stage 40: Silicon carbide substrate

Claims (5)

It is a manufacturing method of semiconductor devices.
A method for manufacturing a semiconductor device, comprising an ion implantation step of irradiating an ion implantation region of a silicon carbide substrate with laser light to heat the ion implantation region of the silicon carbide substrate while implanting ions into the ion implantation region. .. The method for manufacturing a semiconductor device according to claim 1, wherein the laser beam is applied to the surface of the silicon carbide substrate from an oblique direction. The semiconductor according to claim 1 or 2, further comprising a heat treatment step of irradiating the ion-implanted region of the silicon carbide substrate with the laser beam to heat the silicon carbide substrate prior to the ion implantation step. Manufacturing method of the device. Prior to the heat treatment step, a film forming step of forming an external diffusion prevention film on the surface of the silicon carbide substrate is further provided.
The semiconductor device according to claim 3, wherein the outer diffusion prevention film is made of a material that prevents silicon constituting the silicon carbide substrate from diffusing outward from the surface of the silicon carbide substrate. Production method. It is an ion implanter
An ion implantation apparatus including a laser beam irradiating means configured to irradiate an object to be processed with a laser beam.

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