JPH0524983A - Manufacture of semiconductor diamond thin film - Google Patents

Abstract

PURPOSE:To provide method for manufacturing semiconductor diamond capable of controlling the p type and n type by effective doping small in the introduction of defects. CONSTITUTION:A diamond thin film 2 is first formed on a substrate 1 by a CVD deposition method, and when its film thickness reaches a suitable one, the implantation of ions 3 is executed. As the ions 3 to be implanted, III group elements such as B, Al, Ga and In or V group elements such as N, P, As and Sb are effectively used. As for the energy of the ions, the one of 50eV to 100keV is effective. After the doping stage by the above ion implantation, the formation of the diamond thin film 4 is executed once more. In the diamond thin film forming stage by CVD or the like, the selective removing effect of a part having a structure other than diamond (such as a graphite structure) is produced, by which a defective part 5 formed by the ion implantation is removed. On the removed part, diamond is immediately formed, and damage by the ion implantation is not left in the film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semiconductor diamond thin film, which is expected as an environment-resistant element, and particularly utilizes ion implantation of a dopant into diamond to obtain an n-type or p-type semiconductor. The present invention relates to a thin film forming method.

[0002]

2. Description of the Related Art Conventionally, as semiconductor diamonds, natural p-type semiconductor diamonds containing B and synthetic diamonds doped with B have been reported, but no n-type semiconductor diamonds have been reported. Moreover, control of the conductivity type of diamond by ion implantation has not been achieved.
This is because it is difficult to restore the diamond structure destroyed by the ion irradiation by heat treatment. That is, since the equilibrium state of carbon is a graphite structure and the diamond structure is a metastable state, graphite is generated by a normal heat treatment. Diamond thin film is C
It has been reported that it can be formed by a VD vapor deposition method or the like. (Diamond thin film; Kyoritsu Shuppan, Nao Inuzuka) Regarding diamond thin films, B-doped semiconductor diamond thin films have been reported, but formation of n-type semiconductor diamond thin films has not been achieved.

[0003]

In order to form a semiconductor diamond thin film, it is necessary to develop an effective doping method during the formation of a diamond thin film and to introduce few defects. Further, it is necessary to keep the damage caused by the ions as small as possible when the dopant is implanted by the ion implantation so that the implanted ions can efficiently enter the lattice position. It is an object of the present invention to provide a method for manufacturing a semiconductor diamond that solves these problems and that enables efficient doping with few defects introduced.

[0004]

According to the present invention, by performing ion implantation with relatively low energy and diamond thin film formation by CVD deposition alternately, it is possible to suppress the introduction of defects and to perform high-concentration doping. age,
This is to solve the above problem.

[0005]

In the process of forming a diamond thin film such as CVD, a portion having a structure other than diamond (graphite structure or the like) is selectively removed, and a portion of a defect formed by ion implantation is removed. Diamond is immediately formed in the removed portion, and ion implantation damage does not remain in the film. It is considered that the damage due to the ion implantation is formed in the vicinity of the surface of the substrate in the above ion energy range and is mainly distributed closer to the surface than the ion stop position. Therefore, the probability that the dopant is removed by the selective removal is small, while the damage is almost completely removed.

[0006]

EXAMPLE In the present invention, a process of forming a diamond thin film on a substrate and a process of ion implantation are alternately performed to grow a thin film. As shown in FIG. 1, a diamond thin film 2 is first formed on a substrate 1 by a CVD vapor deposition method. When the film thickness becomes appropriate, the gas introduction is stopped and the diamond thin film formation is stopped, and the vacuum degree is raised to 10-4 Torr or less. Next, ion implantation is performed. The ions 3 implanted here are group III elements such as B, Al, Ga, In or N,
It was confirmed that Group V elements such as P, As and Sb were effective. It has been confirmed that the ion energy is effectively 50 eV or more and 100 keV or less. Below 50 eV, the dopant is not driven into the diamond and 100 keV
The above damages the diamond too much. The direction of ion incidence is diamond <110>, <100>, <1
It was also confirmed that the channeling direction such as the 21> direction is effective because deep doping with low damage can be performed.

After the doping process by ion implantation, the diamond thin film 4 is formed again.
In the process of forming a diamond thin film such as CVD, a portion having a structure other than diamond (graphite structure or the like) is selectively removed, and the defect portion 5 formed by ion implantation is removed. Diamond is immediately formed in the removed portion, and ion implantation damage does not remain in the film. It is considered that the damage due to the ion implantation is formed in the vicinity of the surface of the substrate in the above ion energy range and is mainly distributed closer to the surface than the ion stop position 6. Therefore, the probability that the dopant is removed by the selective removal is small, while the damage is almost completely removed.

By this diamond thin film forming process, 5
When the film thickness is 00 nm (if it is less than this, it can be arbitrarily selected in relation to the energy of ion implantation), the growth is stopped,
The process of ion implantation is repeated again. If diamond is formed to a film thickness of 500 nm or more, a uniform dopant profile cannot be obtained due to the subsequent ion implantation.

By repeating the diamond thin film forming process and the ion implantation process in this way, a doping-controlled diamond thin film with little damage could be formed to an arbitrary thickness.

The present invention will be described in more detail with reference to specific examples. (Embodiment 1) A first embodiment of the present invention will be described. First, 1 μm by a microwave plasma CVD method using a Si substrate.
Forming a diamond thin film having a thickness of. Next, the degree of vacuum was set to 1 × 10 −4 Torr, and B was ion-implanted with an energy of 5 keV and a dose amount of 1 × 10 15. Next, a diamond thin film having a film thickness of 100 nm was formed by the microwave CVD method. Next, the same ion implantation of B as described above was performed, and the cycle of ion implantation-diamond thin film formation was repeated 10 times. Finally, a 2 μm diamond thin film showing p-type electrical conductivity was obtained. Similar results were obtained for the other ions described above.

Example 2 Using a diamond single crystal as a substrate, a 100 nm diamond thin film was first formed on the surface of the substrate by a microwave CVD method. Next, B was ion-implanted under the same conditions as in Example 1. The cycle of ion implantation-diamond thin film formation was repeated 10 times. Finally, a 1 μm diamond single crystal thin film showing p-type electrical conductivity was obtained by homoepitaxial growth. Similar results were obtained for the other ions described above.

[0012]

According to the method for producing a semiconductor diamond thin film of the present invention, it is possible to form a semiconductor element using n-type and p-type of diamond, an environment-resistant semiconductor element is obtained, and the industrial value of the present invention is high. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a procedure of a method for producing a semiconductor diamond thin film.

[Explanation of symbols]

1 substrate 2 Diamond thin film 3 Ions to be implanted 4 diamond thin film

Claims (5)

[Claims] 1. A process of irradiating diamond with accelerated particles other than carbon, and a CV for growing a diamond thin film.
A method for producing a semiconductor diamond thin film, characterized in that a process such as D vapor deposition is alternately performed. 2. Particles other than accelerated carbon are B, Al, G.
The method for producing a semiconductor diamond thin film according to claim 1, wherein the group III element such as a and In or the group V element such as N, P, As and Sb is a group V element. 3. The method for producing a semiconductor diamond thin film according to claim 1, wherein the energy of the accelerated particles other than carbon is 50 eV or more and 100 keV or less. 4. The incident direction of accelerated particles other than carbon to diamond is <110> or <100 of diamond.
2. The method for producing a semiconductor diamond thin film according to claim 1, wherein the direction is a channeling direction such as a> or <121> direction. 5. The method for producing a semiconductor diamond thin film according to claim 1, wherein the thickness of the formed film in the process of forming the diamond thin film by CVD deposition is 500 nm or less per cycle.