JPH01203293A - How to form diamond crystals - Google Patents

Abstract

PURPOSE:To easily form diamond crystals useful for an optical thin film, etc., at a low cost by forming recesses having a prescribed depth and width on the surface of a substrate and forming crystals on the substrate by a vapor phase method. CONSTITUTION:Recesses 2 having 50-5,000Angstrom depth and width are formed on the surface of a substrate 1 of a semiconductor such as Si or Ge by dry etching or other method. Mixed gaseous starting materials such as CH4 and H2 are then fed to the surface of the substrate 1 and heated to generate diamond nuclei in the recesses 2 and to form diamond crystals 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming diamond crystals by growing diamond crystals on a substrate by a vapor phase method. Diamond crystals formed according to the present invention can be used, for example, in optical thin films, mechanical protective films for sliding parts, etc., semiconductor integrated circuits, optical integrated circuits, and the like.

[Prior Art] Several methods have been known for forming diamond films and diamond-like carbon films. For example, hydrogen gas and carbon-containing gas are thermally decomposed or made into a plasma state to activate the carbon-containing gas. A method of generating seeds and forming a diamond film on a substrate from the active seeds (Japanese Unexamined Patent Publication No. 58-9
1100, JP-A-58-110494, JP-B-61-2632, etc.), a method of forming a diamond film on a substrate by ionizing a raw material gas and drawing it out using an electric field (JP-A-53-10634) Publications, etc.), sputter deposition is performed by irradiating charged particles onto a target such as graphite or diamond, and a diamond film is formed on the substrate using the sputter-deposited carbon atoms.
The so-called ion beam sputtering method (Japanese Unexamined Patent Publication No. 56-226
Publication No. 16, etc.).

Furthermore, it is known that if scratches are formed on the surface of a substrate using diamond abrasive grains or the like in advance and the vapor phase method described above is applied to the substrate, the density of diamond nucleation in the scratched portions increases. .

[Problem to be solved by the invention]

However, when the nucleation density is increased by the formation of scratches, it is still unclear what type of scratches can improve the diamond nucleation density.

The purpose of the present invention is to find the size and depth of scratches (concavities) on a substrate that can favorably generate diamond nuclei, and to provide a method for easily forming diamond crystals by forming such scratches. It's about doing.

[Means for Solving the Problems] The present invention provides a method for forming a diamond crystal that includes a process of growing a diamond crystal on a substrate by a vapor phase method, in which a recess with a depth and width of 50 to 5000 A is formed on the substrate in advance. This is a method for forming a diamond crystal, which is characterized by forming a diamond crystal.

Hereinafter, the method of the present invention will be explained in detail along the steps and with reference to the drawings. Note that FIGS. 1(a) and 1(b) are drawings for briefly explaining the steps of the present invention, and FIG.
Figure (b) is a partial cross-sectional view of the substrate after diamond nuclei have grown.

First, a substrate is prepared on the surface of which a diamond crystal can be grown by a vapor phase method. Examples of such substrates include semiconductor substrates such as Si and Ge, oxide substrates such as quartz, and metal substrates such as Mo and W. Note that, as will be described later, using the method of the present invention makes it easier to generate diamond nuclei, so it may be possible to use a substrate made of a material in which diamond nuclei are conventionally difficult to grow.

Next, as shown in FIG. 1(a), a recess 2 is formed on the base 1 at a portion where a diamond crystal is to be formed. The recess can be of any shape with a depth and width of 50 to 5000 Å, preferably 100 to 500 Å. For example, it may be linear or dotted, and in the case of a linear recess, the length of the flaw may be 5000A or more as long as the width of the flaw is within the above range. The method for forming the recesses is not limited to a specific method, for example, FIB (
It can be formed by various methods such as a focused ion beam method, an EB chrysography method, a dry etching method, a wet etching method, and a mechanical method. In the present invention, by forming recesses selectively on the substrate, a thin film pattern made of diamond crystal can be easily formed.

Next, as shown in FIG. 1(b), a diamond crystal is grown on the base 1 in which the recess 2 is formed by a vapor phase method. At this time, since diamond nuclei are easily generated from the concave portion 2 on the base 1, the diamond crystal 3
begins to grow easily.

[Example J Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example I A large number of hole-shaped recesses with various diameters as shown in Table 1 were formed on a St (100) single crystal substrate by a patterning method using an electronic lithography device. Note that the diameter of the substrate was 1 inch and the thickness was 0.5 mm.

Next, a diamond film was formed on the substrate by the W filament method for 5 minutes. Note that the raw material gas used at this time was a mixed gas of CH4 and H2 with a CH4 concentration of 0.5%. Also, the pressure is 50 Torr, and the substrate temperature is 850
°C, and the filament temperature was 2100 °C.

With the above film formation, the diameter of the concave portion on the substrate is 100 to 2.
00A diamond crystals were precipitated, and almost no diamond crystals were generated in areas other than the recesses.

Table 1 shows the probability of diamond crystal formation for the concave portion of the can diameter. From these results, it was confirmed that diamond nuclei could be favorably generated according to the present invention.

Comparative Example 1 A film was formed in the same manner as in Example 1 except that no recesses were formed. Table 1 shows the number of crystal nuclei precipitated per 1 am2.

Comparative Example 2 A film was formed in the same manner as in Example 1 except that the diameter of the recess was 10,000. From the results shown in Table 1, it was confirmed that the width of the recessed portion of the present invention is effective when it is 5000A or less.

Table 1 [Effects of the Invention 1 As explained above, according to the present invention, a recess with a depth and width suitable for the growth of diamond crystals is formed on the substrate, so that the diamond crystal can be grown on the recess. can be easily grown using the vapor phase method. therefore,
Manufacturing costs can be reduced, and furthermore, a thin film pattern made of Guyanmond crystal can be easily formed.

The diamond crystal formed by the method of the present invention as described above is useful for use in, for example, optical thin films, mechanical protective films for sliding parts, etc., semiconductor integrated circuits, optical integrated circuits, and the like.

[Brief explanation of the drawing]

FIG. 1(a) is a partial cross-sectional view of the substrate in which a recess is formed, and FIG. 1(b) is a partial cross-sectional view of the substrate after diamond nuclei have grown. 1...Base 2...Recess 3...Diamond core patent applicant Canon Co., Ltd.

Claims (1)

[Claims] A method for forming a diamond crystal, which includes the step of growing a diamond crystal on a substrate by a vapor phase method, characterized in that a recess having a depth and width of 50 to 5000 Å is formed in advance on the substrate. Method.