JP3111623B2 - Method for producing vapor-phase synthetic diamond film with excellent surface smoothness - Google Patents

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 vapor-phase synthetic diamond film having excellent surface smoothness.

[0002]

2. Description of the Related Art In recent years, insulating films of electronic materials, heat transfer films, X
As a thin film such as a line exposure mask, a vapor-phase synthetic diamond film has been used. In general, the vapor-phase synthetic diamond film is subjected to friction or collision treatment on the polished and chemically etched surface of the Si wafer using diamond powder, and then, the surface of the friction or collision-treated Si wafer is subjected to normal gas synthesis. It is also known that it is formed by depositing and forming a diamond film by the method (for example, see JP-A-60-86096).

[0003]

The vapor-phase synthetic diamond film used for the insulating film, the heat transfer film, the mask for X-ray exposure, etc. of the above-mentioned electronic material is required to have as excellent surface smoothness as possible. However, none of the diamond films formed on the surface of the conventional Si wafer has sufficient surface smoothness because of the ultrasonic polishing treatment or the lapping treatment using a solution in which ordinary diamond fine powder is suspended and dispersed. Inevitably, a large scratch is formed on the surface of the Si wafer that has been damaged, and even if a vapor-phase synthetic diamond film is formed on the surface of the Si wafer having such a large scratch, it is possible to produce a vapor-phase synthetic diamond film having excellent surface smoothness. There was a problem that could not be done. However, omitting the friction or collision treatment so as not to damage the surface of the Si wafer extremely deteriorates the deposition and formation of the vapor-phase synthetic diamond film. There is no go.

[0004]

Therefore, the present inventor has proposed an S
Treat the surface of the i-wafer so that it will not be damaged
As a result of research on obtaining a vapor-phase synthetic diamond film having excellent surface smoothness, a round ultrafine diamond powder having an average particle diameter of 20 to 500 Å, preferably an average particle diameter of 40 to 80 Å. When the surface of the Si wafer is subjected to ultrasonic treatment or friction treatment using, a Si wafer having a smooth surface without large scratches on the surface of the Si wafer is obtained. It has been found that forming a diamond film by the method yields a vapor-phase synthetic diamond film having a smooth surface.

The present invention has been made based on this finding. (1) Ultrasonic treatment of a surface-polished Si wafer in a solution in which a round ultrafine diamond powder is suspended and dispersed, Forming a diamond film on the surface of a sonicated Si wafer by a gas phase synthesis method, a method for producing a vapor phase synthetic diamond film having excellent surface smoothness, (2) polishing the surface of the polished Si wafer to a round ultrafine diamond By rubbing with powder, S
a method for producing a vapor-phase synthetic diamond film having excellent surface smoothness, in which a surface of an i-wafer is subjected to a friction treatment, and then a diamond film is formed on the surface of the friction-treated Si wafer by a vapor-phase synthesis method. is there.

[0006] It has been found that ultrasonic treatment or friction treatment using the round ultrafine diamond powder is effective for diamond nucleation without causing significant damage to the surface of the Si wafer. The reason for this is that the crystals having a surface number of 10 angstroms are disturbed without such large scratches, and some of the ultra-fine diamond powder is left behind. Thus, when a diamond film is deposited and formed, nucleus formation is facilitated and a vapor-phase synthetic diamond film having excellent surface smoothness can be obtained.

[0007] The round ultrafine diamond powder used in the present invention is produced by detonating in an inert atmosphere and synthesizing carbon into diamond, showing a shape close to a sphere such as a sphere or an ellipsoid, and the average particle size thereof. Diameter is 20 ~
Preferably, the average particle diameter is in the range of 500 angstroms, particularly 40 to 80 angstroms. The average particle size of the round ultrafine diamond powder is 20 to 500.
The reason for limiting to Angstroms is that if the average particle size is less than 20 Angstroms, the surface is too fine to be efficiently subjected to ultrasonic treatment or friction treatment on the Si wafer surface, and the surface crystal disorder is sufficient for diamond nucleation. On the other hand, if it exceeds 500 angstroms, scratches will remain.

[0008]

【Example】

Example 1 A disk-shaped Si wafer having a surface of mechanically polished and having a radius of 75 mm was prepared, and immersed in an acetone solution in which a round ultrafine diamond powder produced by an explosion method with an average particle size of 50 Å was suspended and dispersed. The surface was activated by applying 1 MHz ultrasonic waves.

The thus-obtained Si wafer having a smooth surface is loaded into a quartz reaction vessel provided with a metal W filament, and the atmosphere pressure is 30 Torr, the substrate temperature is 750 ° C., and the reaction gas is methane gas / hydrogen gas. = 1.0% mixed gas, a gas-phase synthetic reaction was performed under the following conditions, a gas-phase synthetic diamond film having an average layer thickness of 2 μm was formed, and the surface roughness of the diamond film was measured by STM. Rmax: 100 angstroms Met.

Conventional Example 1 The chemically etched Si wafer prepared in Example 1 was subjected to ultrasonic wave in which square ultrafine diamond powder having an average particle size of 5 μm and manufactured by a normal ultrahigh pressure synthesis method was suspended and dispersed. The surface was activated by immersing it in a polishing liquid and applying 1 MHz ultrasonic waves, and the average layer thickness: 2 μm was applied to the surface of the thus obtained Si wafer by a gas phase synthesis method under the same conditions as in Example 1. To form a vapor-phase synthetic diamond film,
When the surface roughness of this diamond film was measured by STM, it was Rmax: 5000 Å.

Example 2 The chemically etched Si wafer prepared in Example 1 was subjected to friction treatment using a round ultrafine diamond powder produced by an explosion method having an average particle size of 40 Å. Then, on the surface of the friction-treated Si wafer, an average layer thickness was obtained by a vapor phase synthesis method under the same conditions as in Example 1.
A 2 μm vapor-phase synthetic diamond film was formed, and the surface roughness of the diamond film was measured by STM.
x: 200 angstroms.

Conventional Example 2 The chemically etched Si wafer prepared in Example 1 was subjected to friction treatment using ordinary square ultrafine diamond powder having an average particle diameter of 30 μm, and then subjected to friction treatment.
On the surface of the i-wafer, a vapor-phase synthetic diamond film having an average layer thickness of 2 μm was formed by a vapor-phase synthesis method under the same conditions as in Example 1, and the surface roughness of the diamond film was measured by STM to find that Rmax was 2000 Å. there were.

[0013]

From the measurement results shown in Examples 1 and 2 and Conventional Examples 1 and 2, the round ultrafine diamond fine powder produced by the explosion method of Examples 1 and 2 of the present invention was suspended and dispersed. The vapor-phase synthetic diamond film formed on the surface of the Si wafer subjected to the ultrasonic treatment or the friction treatment using the prepared solution is formed by using the angular ultrafine diamond powder produced by the ordinary ultra-high pressure synthesis method of Conventional Examples 1 and 2. It can be seen that the surface roughness is smaller and the surface is smoother than the vapor-phase synthetic diamond film formed on the surface of the Si wafer subjected to the ultrasonic polishing treatment or the friction treatment.

Therefore, the present invention can provide a vapor-phase synthetic diamond film having a smoother surface than conventional ones, and provide a thin film such as an insulating film, a heat transfer film, and an X-ray exposure mask excellent in electronic material. It has excellent industrial effects.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Takeuchi 2-10-11 Kasuga, Bunkyo-ku, Tokyo Jeunesse ARITA201 (56) References JP-A-1-119671 (JP, A) JP-A-61-163276 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 16/02 C23C 16/27 C30B 29/04 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A surface-polished Si wafer is subjected to ultrasonic treatment in a solution in which a round ultrafine diamond powder is suspended and dispersed, and then a diamond film is formed on the surface of the ultrasonically treated Si wafer by a gas phase synthesis method. A method for producing a vapor phase synthetic diamond film having excellent surface smoothness, characterized by being formed. 2. The surface of the polished Si wafer is rubbed by rubbing the surface of the Si wafer with a round ultrafine diamond powder, and then the surface of the rubbed Si wafer is subjected to a gas phase synthesis method. A method for producing a vapor-phase synthetic diamond film having excellent surface smoothness, characterized by forming a diamond film. 3. The round ultrafine diamond powder,
It is manufactured by the explosion method and has an average particle size of 20 to 500.
3. The method for producing a vapor-phase synthetic diamond film having excellent surface smoothness according to claim 1, wherein the thickness is in the range of angstrom.