JPH03215392A - Manufacturing method of single crystal diamond - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing single crystal diamond, which is used particularly in the semiconductor field.

[Conventional technology]

Conventional methods for forming diamond thin films include hot filament CVD and microwave CVD. In the hot filament CVD method, the temperature inside the reaction chamber in which the filament and the substrate are installed is maintained at several tens of Torr, and
Reaction gases are introduced into this reaction chamber and heated by a filament to form a film. Furthermore, in the microwave CVD method, microwaves and a reaction gas are introduced into a reaction chamber in which a substrate is installed, and the reaction gas is decomposed by plasma generated using the microwave to form a film. There is.

[Problem to be solved by the invention]

In the conventional diamond thin film manufacturing method as described above,
Only polycrystalline films have been produced on foreign substrates. Furthermore, it is necessary to perform scratching treatment on the substrate before film formation.

As shown in FIGS. 6A and 6B, the polycrystalline film does not have a simple columnar structure because the size and growth process of each grain of the diamond 10 varies. Therefore, when uniform film quality and film thickness are required, it has been extremely difficult to manufacture them.

Therefore, the selective growth method used for silicon and the like has recently been applied to the production of diamond thin films.

In the selective growth method, an insulating layer such as a silicon oxide film is patterned on a silicon substrate, and the position where diamond nuclei are formed on the substrate is controlled.

However, in the selective growth method, it is essential to damage the substrate before patterning. This scratching process involves polishing the substrate surface with diamond paste or placing diamond abrasive grains in alcohol and subjecting them to ultrasonic treatment, but this process is very time-consuming. There is also a method of performing board damage reduction treatment after turning with bumps.
This process also requires work such as irradiation with an argon beam, which poses the problem of being time-consuming.

An object of the present invention is to provide a method for manufacturing single-crystal diamond that can manufacture single-crystal diamond without any scratching treatment.

[Means for Solving the Problems] The method for manufacturing single crystal diamond according to this invention includes the following steps.

◎ Forming an insulating layer with microholes at predetermined intervals on the surface of a conductive substrate.

◎The pressure in the reaction chamber where the substrate is placed must be set to a low pressure range where the bias effect appears.

O vapor phase growing a single crystal diamond thin film on the substrate under diamond film forming conditions while applying a positive bias voltage to the substrate;

[Effect]

In the present invention, the location where diamond nuclei are to be generated is designated by pattern processing. Pattern processing is performed in the same manner as in the conventional selective growth method, but the patterned substrate is processed without scratching, at a low pressure (below 10 Torr) where a bias effect occurs, and in addition, a positive bias is applied to the substrate. Generation is performed under diamond generation conditions while applying voltage.

Then, since the portion of the insulating layer on the substrate is in an electrically floating state, the potential becomes lower than the plasma potential. Therefore, only ions reach this insulating layer, and diamonds are not generated. On the other hand, since a positive bias voltage is applied to the microholes formed by patterning, that is, the exposed parts of the substrate, electrons gather, and diamonds are generated only in these parts.

By making this hole an appropriate size, a single crystal diamond grows in the center.

〔Example〕

FIG. 4 is a schematic cross-sectional configuration diagram of a film forming apparatus to which a diamond manufacturing method according to an embodiment of the present invention is applied. The plasma chamber 1 has a cavity structure, and a magnetron (not shown) as a microwave source is connected to the plasma chamber 1 via a waveguide 2. Further, the plasma chamber 1 is provided with a reactive gas supply port 1a, through which a reactive gas is introduced. Here, a mixed gas of carbon monoxide gas (CO) and hydrogen gas (HE) is used as the reaction gas. Electromagnets 3a and 3b are arranged around the plasma chamber 1, and these electromagnets 3a and 3
The strength of the magnetic field due to b is ma? The conditions for electron cyclotron resonance due to mouth waves are set so that they are established inside the plasma chamber l.

Further, a substrate 5 on which diamond is to be produced is placed near a position in the plasma chamber 1 where conditions for electron cyclotron resonance are satisfied. This substrate 5 is held by a substrate holder 6, and the substrate holder 6 is provided with a heater 7. Further, a positive DC bias voltage can be applied to the substrate 5 via an external DC bias power supply 8.

Next, a method for manufacturing single crystal diamond will be explained.

First, as shown in the plan view in FIG. IA and the cross-sectional view in FIG. The micro holes 4a are formed at equal intervals. this hole 4
The distance L between the holes a is about 10 μm, and the diameter l of the hole 4a is 1 μm.
degree.

Here, the distance L between the holes 4a is what you want to finally form? It can be changed depending on the thickness, but the diameter of the hole 4a! If it is made too large, the diamond produced will not be one single crystal but two or more or polycrystalline. If the thickness is 5 μm or more, multiple pieces are likely to be formed.

Next, the substrate 5 on which the SiO2 film is formed is mounted on the substrate holder 6 in the plasma chamber l. After evacuating the inside of the plasma chamber 1, carbon monoxide gas and hydrogen gas are introduced, and the pressure is set to a low pressure (0.IT) where a bias effect can occur.
orr).

Note that the bias effect is an effect unique to low pressure, in which diamond is generated when a positive bias voltage is applied to the substrate, and no diamond is generated when it is negative.

Next, microwaves are generated from the magnetron and introduced into the plasma chamber 1 via the waveguide 2,
A current is passed through the electromagnets 3a and 3b to form a magnetic field. At this time, electron cyclotron resonance occurs at a predetermined position in the plasma chamber 1, and the electrons efficiently absorb energy from the microwave. , a plasma region is formed under low pressure. Further, a positive DC bias of about 10 to 60 V is applied to the base Fi5 by a DC bias power supply 8. Note that the generation conditions are low pressure (0, I Torr) as described above.
), for example, the microwave power is 1300W, the substrate temperature is 650°C, GO/CO+
It is sufficient to set Hz = 5%.

When the generation is performed in the above state, as described above, the Sin. The portion of the membrane 4 becomes electrically floating. For this reason, the potential becomes lower than the plasma potential, and S
Only ions reach the iO2 film 4, as shown in FIG.

Therefore, no diamonds are produced. On the other hand, hole 4
Since a positive bias voltage is applied to the substrate 5, electrons gather in the exposed portion of the substrate 5 in the portion a, and diamonds are generated only in this portion. Then, one single crystal diamond 10 is formed at the center of each hole 4a in about two hours after the start of formation. This state is shown in FIG. 3A. And furthermore, will it continue to generate as it is? , the particles collide with each other, and after passing through the state shown in FIG. 3B, a substantially flat film is formed as shown in FIG. 3C.

The film thickness t at this time is determined by the interval between the holes 4a.

[Other Examples] (a) In the above embodiment, the SiO film 4 was left on the surface of the substrate 5, but the SiO film 4 was
Once the nucleus is formed, it may be removed. That is, Si
After the nt film 4 is removed, the substrate that has not been subjected to any processing is exposed, so even if the generation continues, diamond nuclei will not be generated in this area.

(b) In the above embodiment, the holes 4a formed by patterning were arranged at equal intervals, but the intervals between the holes 4a do not need to be equal, and may be changed as necessary.

For example, when making MES-FETs, diamond may be used as a conductive wire.

When creating an FET as shown in Figure 5A,
Holes 4b may be formed at intervals as shown in the figure and patterned for conductive wires. In addition, in FIG. 5A, 11 is a gate, 12.13 is a source, a drain, 14a, 14
b and a diamond film as a conducting wire.

(C) The diamond produced in the above embodiment can be used not only by being attached to the surface of the substrate 5, but also by being removed from the substrate 5 by etching or the like and used as an abrasive grain. At this time, if the patterns on the substrate 5 are arranged at equal intervals, abrasive grains with uniform grain sizes can be created.

(d) In the above embodiment, a magnetic field Cv is used as the CVD method.
Although method D was used, it does not necessarily have to be a magnetic field, and is not limited as long as it can form a film under low pressure.

〔Effect of the invention〕

As described above, in the present invention, since diamond is generated under low pressure while applying a positive DC bias, there is no need to scratch the substrate, which was indispensable in the past, and the work is simplified. Further, since the nucleus is generated from the center of the hole in the substrate, the adhesion with ah is good.

[Brief explanation of drawings]

Fig. IA is a plan view of a patterned substrate used in the method of this embodiment, Fig. IB is a sectional view taken along the line IB-IB, and Fig. 2 shows the effect when a positive DC bias voltage is applied to the substrate. Figures 3A and 3B, which are explanatory diagrams, are cross-sectional views showing the growth of a diamond single crystal, and Figure 4 is a schematic cross-sectional configuration diagram of a film forming apparatus to which the method of this embodiment is applied, and Figures 5A and 3B are cross-sectional views showing the growth of a diamond single crystal. FIG. 5B is a diagram for explaining another embodiment of the present invention, FIG. 6A is a plan view of a diamond manufactured by a conventional method, and FIG. 6B is a cross-sectional view thereof. 4...Sin. Film (insulating layer), 5...substrate, 8...
・DC bias power supply.

Claims (1)

[Claims] (1) Forming an insulating layer having microholes at predetermined intervals on the surface of a conductive substrate; setting the pressure in a reaction chamber in which the substrate is placed to a low pressure range where a bias effect appears; and A method for producing single crystal diamond, comprising: growing single crystal diamond on the substrate in a vapor phase under diamond forming conditions while applying a positive bias voltage to the substrate.