JPH0963982A - Semiconductor device formed by controlling conductive type by knock-on - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop the technique with which the conductive type of a superthin region can be controlled easily by utilizing the phenomenon called knock-on, and also to develop a semiconductor device by adapting the above- mentioned technique. SOLUTION: A thin film 2 is formed on a semiconductor board 1, the atoms of the thin film 2 are implanted to the semiconductor board 2 by ion-implanting to the thin film 2, the conductive type of the semiconductor board 1 is controlled, and a semiconductor device is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device.

[0002]

2. Description of the Related Art There is a technique of implanting ions into a semiconductor substrate made of gallium arsenide or silicon to heat-treat it, and controlling the conductivity type of the implanted portion of the semiconductor substrate to produce a transistor or a diode. This is called an ion implantation method. The ion implantation method can strictly control the carrier concentration.
However, it was difficult to control the conductivity type only in an extremely thin region by the ion implantation method. With a certain probability, the implanted ions go through the gaps between the atoms of the semiconductor substrate, and the carrier concentration has a distribution that is tailed in the depth direction.

[0003]

In recent years, there has been an increasing demand for higher integration, miniaturization, and higher speed of semiconductor elements, and the establishment of a technique for controlling the conduction type in an ultrathin region has been desired.
The present invention intends to develop a technique for easily controlling the conduction type in an extremely thin region by utilizing the phenomenon of knock-on, and to apply this to develop a semiconductor device.

[0004]

A method of controlling conduction type in an extremely thin region by knock-on will be described with reference to FIG. (A) The thin film (2) is formed on the semiconductor substrate (1). (B) A mask of photoresist (3) is further attached to the semiconductor substrate (1) on which the thin film (2) is attached. (C) Ion implantation is performed on the semiconductor substrate (1) provided with the thin film (2) and the photoresist (3). (D) The implanted ions (4) pass through the thin film (2) and reach the inside of the semiconductor substrate (1) to form a doping layer (5) for the implanted ions. (E) When the implanted ions (4) pass through the thin film (2), they strike the atoms of the thin film (2) to knock them out. This phenomenon is called knock-on. As a result, the atoms of the thin film (2) enter the semiconductor substrate (1). Then, a very thin knock-on doping layer (6) is formed. (F) When the photoresist (3) is removed and heat treatment is performed, the implanted ion doping layer (5) and the knock-on doping layer (6) function as p-type or n-type doping layers, respectively. .

[0005]

The atoms of the thin film (2) entering the semiconductor substrate (1) due to the knock-on move only a short distance in the semiconductor substrate (1) as compared with the implanted ions (4). Therefore, a doping layer (6) is formed by knocking on atoms of the thin film (2) that are extremely thin. With this method, it is possible to easily control the conductivity type in the extremely thin region.

[0006]

Example 1 Using a semiconductor substrate (1) with gallium arsenide, a thin film (2) with magnesium nitride, and implanted ions (4) with silicon atoms, ion implantation was performed by the method shown in the means for solving the above problems. A doping layer is formed. Depending on the thickness of the thin film (2), the energy of the implanted ions (4), and the amount of implantation, by adjusting these, the implanted ion doping layer (5) becomes n-type, and the knock-on doping layer (6). Can be p-type. This pn junction can be used as a diode.

[0007]

Example 2 Using a semiconductor substrate (1) using gallium arsenide, a thin film (2) using magnesium nitride, and implanting ions (4) using silicon atoms, ion implantation was performed by the method shown in the means for solving the above problems. A doping layer is formed. Depending on the thickness of the thin film (2), the energy of the implanted ions (4), and the amount of implantation, by adjusting these, the implanted ion doping layer (5) becomes n-type, and the knock-on doping layer (6). Can be of a weaker n-type than the implanted ion doping layer (5). Magnesium nitride magnesium atom knocks on semiconductor substrate (1)
This is because it neutralizes the action of the silicon atoms of the implanted ions (4) having the action of turning gallium arsenide into an n-type semiconductor. After that, as shown in FIG. 2, a metal film (7) is formed on the doping layer. A depletion layer (8) is formed at the interface of the semiconductor substrate (1) with the metal film (7) and exhibits electrical rectification characteristics. It functions as a Schottky diode. Even if there is no knock-on doping layer (6), a depletion layer (8) is formed at the interface with the metal film (7) of the semiconductor substrate (1) and exhibits rectifying characteristics, but there is a knock-on doping layer (6). Compared to the case, the depletion layer (8) becomes thinner and the reverse breakdown voltage becomes lower due to the leakage current due to the tunnel effect.

[0008]

Example 3 Using the semiconductor substrate (1) gallium arsenide, the thin film (2) silicon nitride, and the implanted ions (4) silicon atoms, ion implantation is performed by the method described above as means for solving the problems. Then, a doping layer is formed. Depending on the thickness of the thin film (2), the energy of the implanted ions (4), and the amount of implantation, by adjusting these, the implanted ion doping layer (5) becomes n-type, and the knock-on doping layer (6). Can be a stronger n-type. This is because silicon atoms of silicon nitride enter into the semiconductor substrate (1) by knocking on and the concentration of silicon near the surface of the semiconductor substrate (1) increases. Thereafter, as shown in FIG. 3, a low melting point metal film (9) is formed on the doping layer and heat-treated. Then, the interface between the semiconductor substrate (1) and the low melting point metal film (9) exhibits ohmic characteristics. Although the interface with the low melting point metal film (9) of the semiconductor substrate (1) shows ohmic characteristics even when the knock-on doping layer (6) is not present, the electrical resistance becomes smaller when the knock-on doping layer (6) is present. Become. This can be used for the electrode portion where the semiconductor device exchanges electric power and signals with the outside.

[0009]

Fourth Embodiment FIG. 4 shows a gallium arsenide field effect transistor produced by applying the conduction type control method shown in the first embodiment to form the channel (10). K-on p-type doping layer (11) for channel (10)
have.

[0010]

Fifth Embodiment FIG. 5 shows a gallium arsenide field effect transistor produced by applying the conduction type control method shown in the second embodiment to the formation of the channel (10). Since the channel (10) has the weak n-type doping layer (16) due to knock-on, the reverse breakdown voltage of the gate electrode (12) is high.

[0011]

Sixth Embodiment When a gallium arsenide field effect transistor is produced, magnesium or beryllium is ion-implanted with a higher energy to form a buried p-type doping layer (17) of implanted ions under the channel (10). There is. When a thin film of magnesium nitride is formed on the semiconductor substrate of gallium arsenide at the time of this ion implantation, magnesium atoms of magnesium nitride enter into the semiconductor substrate by knock-on, and p-type is doped on the upper part of the channel (12). There are created layers. After fabrication of the entire field effect transistor, the upper part of the channel (10) becomes a p-type or weak n-type doping layer (18) due to knock-on. If there is a p-type or weak n-type doping layer (18) due to knock-on, the reverse breakdown voltage of the gate electrode (12) becomes high. FIG. 6 shows the configuration.

[0012]

Example 7 Silicon was used for the semiconductor substrate (1), yellow phosphorus was used for the thin film (2), and boron atoms were used for the implanted ions (4).
Ion implantation and doping layer formation are carried out by the method shown in the means for solving the above problems. These are adjusted depending on the thickness of the thin film (2), the energy of the implanted ions (4), and the implantation amount. As a result, the implanted ion doping layer (5) becomes n-type, and the knocked-on doping layer (6)
Can be p-type. This pn junction can be used as a diode.

[0013]

[Effect] Next, the effect of the embodiment will be described.

In the first embodiment, the pn junction can be formed by one-time ion implantation, and the process of manufacturing the pn junction diode can be simplified.

The second embodiment can form a Schottky diode having a high reverse breakdown voltage.

In the third embodiment, the semiconductor device can be used in the electrode portion for exchanging power and signals with the outside, and the electric resistance of the electrode portion is lowered.

The fourth, fifth and sixth embodiments can be field effect transistors having a high reverse breakdown voltage of the gate electrode (12). The characteristics of the fourth embodiment, the fifth embodiment, and the sixth embodiment are different from each other. Therefore, when these are used to configure an electronic circuit, they are properly used.

In the seventh embodiment, the pn junction can be formed by one-time ion implantation, and the process of making a diode can be simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of controlling a conduction type in an extremely thin region by knocking on.

FIG. 2 is a cross-sectional view of a Schottky diode using a weak n-type doping layer formed by knock-on.

FIG. 3 is a cross-sectional view of an electrode portion in which a semiconductor device uses a strong n-type doping layer formed by knock-on to exchange power and signals with the outside.

FIG. 4 shows a pn formed by knocking on a channel.
FIG. 6 is a cross-sectional view of a gallium arsenide field effect transistor having a junction.

FIG. 5 is a cross-sectional view of a gallium arsenide field effect transistor having a weak n-type doping layer formed in the channel by knock-on.

FIG. 6 has a p-type or weak n-type doping layer formed on the channel by knock-on associated with ion implantation when forming a buried p-type doping layer,
FIG. 3 is a cross-sectional view of a gallium arsenide field effect transistor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Thin film 3 Photoresist 4 Implanted ions 5 Doped layer of implanted ions 6 Doping layer by knock-on 7 Metal film 8 Depletion layer 9 Low melting point metal film 10 Channel 11 P-type doping layer by knock-on 12 Gate electrode 13 n + layer 14 Source electrode 15 Drain electrode 16 Weak n-type doping layer due to knock-on 17 Embedding p-type doping layer of implanted ions 18 P-type or weak n-type doping layer due to knock-on

Claims (12)

[Claims] 1. A thin film (2) is formed on a semiconductor substrate (1), and by implanting ions through the thin film (2), the atoms of the thin film (2) are implanted into the semiconductor substrate (1) to obtain a semiconductor substrate. A semiconductor device produced by controlling the conductivity type of (1). 2. A pn junction formed by performing conductivity type control according to claim 1, wherein gallium arsenide is used for the semiconductor substrate (1), magnesium nitride is used for the thin film (2), and silicon atoms are used for implanted ions (4). 3. A pn junction diode using the pn junction according to claim 2. 4. A weak n-type semiconductor formed by conducting type control according to claim 1, wherein gallium arsenide is used for the semiconductor substrate (1), magnesium nitride is used for the thin film (2), and silicon atoms are used for implanted ions (4). Doping layer. 5. A Schottky diode using the weak n-type doping layer of claim 4. 6. A semiconductor substrate (1) is made of gallium arsenide, a thin film (2) is made of silicon nitride, and implanted ions (4) are made of silicon atoms. Doping layer. 7. An electrode portion, which uses the strong n-type doping layer according to claim 6, for a semiconductor device to exchange power and signals with the outside. 8. A gallium arsenide field effect transistor having a pn junction according to claim 2 in a channel (10). 9. The weak n of claim 4 in the channel (10).
-Field-effect transistor with gallium arsenide doping layer. 10. A gallium arsenide field effect transistor having a p-type doping layer (19) formed on the channel upper portion by knock-on accompanying ion implantation when forming a buried p-type doping layer (18) of implanted ions. 11. A gallium arsenide field effect transistor having a weak n-type doping layer (19) formed on the channel by knock-on accompanying ion implantation when forming a buried p-type doping layer (18) of implanted ions. . 12. The semiconductor substrate (1) is made of silicon, the thin film (2) is made of yellow phosphorus, and the implanted ions (4) are made of boron atoms.
A pn junction formed by forming the doping layer according to claim 1.