Method for manufacturing diamond-like carbon film

Abstract

A method for manufacturing diamond-like carbon (DLC) film is disclosed. The method mainly includes steps of: (a) fixing a substrate in a reaction chamber; (b) pumping the pressure of the reaction chamber below 10−6 torr; (c) introducing at least a carbon-containing gas into the reaction chamber; and (d) depositing a diamond-like carbon film on the substrate by sputtering a graphite target. The deposited DLC film is in a shape of flakes. The appearance of the deposited DLC film on the surface of the substrate is in a rose-like shape. Moreover, the height of the deposited DLC film is of micrometer level, and the thickness of the deposited DLC film is of nanometer level. Since the aspect ratio of the deposited flake-shaped DLC film is high, the deposited DLC film can enhance the field emission.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic expression of the sputtering reaction chamber 100 for preparing the diamond-like carbon film in a preferred embodiment of the present invention;

FIG. 2 a is an SEM photo showing the front surface of the substrate having a diamond-like carbon film on the surface in the preferred embodiment;

FIG. 2 b is an SEM photo of the lateral side of the substrate having a diamond-like carbon film on the surface in this preferred embodiment;

FIG. 2 c is an SEM photo of the diamond-like carbon film manufactured in this example, which was scraped off and put on the front surface of the substrate; and

FIG. 3 is the Raman spectrum of the diamond-like carbon film prepared in Examples 2 to 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

EXAMPLE 1

The method for manufacturing a diamond-like carbon film in a preferred embodiment of the present invention is illustrated as following. FIG. 1 is a schematic expression of the sputtering reaction chamber 100 for preparing the diamond-like carbon film in this example.

First a reaction chamber 100 for reaction was provided, which comprised a heater for heating substrate 1, a stage 11 for loading substrate 1, a power source 13 for applying voltage to target 12, and a plurality of gas-supplying elements A, B, and C for providing gas. Note that during manufacture of the diamond-like carbon film, the gas-supplying elements can be added or removed depending on the gas conditions required in the process, and are not limited to the setup described in this example.

Subsequently, the surface of the substrate was cleaned, and the substrate 1 was loaded on the stage 100 in the reaction chamber 11 to be fixed. Substrate 1 in this example is a silicon wafer made of a semiconductor. Pressure of reaction chamber 100 was pumped to below 1×10⁻⁵ torr, and substrate 1 was heated with a heater 10 to 400° C.

Then gases were provided by the gas-supplying elements A, B, and C, and the gas flow into the reaction chamber 100 was controlled by a mass flow controller (not shown). Gas-supplying elements A, B, and C in this example are sources of argon, methane, and hydrogen, respectively. Plus, whether the three gases were introduced into the reaction chamber 100 was controlled by gas-supplying a1, b1, and c1, in accordance with process conditions. In the example, gases introduced into the reaction chamber 100 include argon, methane, and hydrogen, with a ratio of 2:1:1.

In this example, when the reaction gases were introduced into reaction chamber 100, the pressure of the reaction was controlled around 9×10⁻³ torr. Of course, the pressure in the environment in which sputtering takes place is not restricted to that described in this example, and is adjustable depending on the requirements of the process.

Then pre-sputtering was performed on the graphite target 12 for 30 minutes with 200 W RF power, so that contaminants possibly existing on the surface of the graphite target 12 were cleared. Subsequently, shield 111 was opened, and the surface of substrate 1 was sputtered for 70 minutes to form a diamond-like carbon film on the surface of substrate 1.

Referring to FIGS. 2a, 2b, and 2c, FIG. 2a is an SEM photo showing the front surface of the substrate having a diamond-like carbon film on the surface in the preferred embodiment. FIG. 2b is an SEM photo of the lateral side of the substrate having a diamond-like carbon film on the surface in this preferred embodiment. FIG. 2c is an SEM photo of the diamond-like carbon film manufactured in this example, which was scraped off and put on the front surface of the substrate.

As shown in FIGS. 2a and 2b, the diamond-like carbon film prepared in this example was in a curved-strip shape or a long-strip shape, and the flake-shaped structure was arranged on the surface of substrate 1 in a 3-D rose-like pattern, wherein the average height of the flake-shaped structure was 1 μm, and the average thickness of each flake was 10 nm to 20 nm, such that the structure having a “high aspect ration” emphasized in the present invention was formed. Referring to FIG. 2c, when the formed diamond-like carbon film was scraped and positioned on the substrate, the average thickness was 10 nm to 20 nm, and the width was 1-3 μm.

Therefore, the diamond-like carbon film prepared in this example has a high aspect ratio, and the substrate was made of a conductive semiconductor material, the film can be directly applied in electron emission.

EXAMPLES 2 TO 6

Examples 2 to 6 proceeded with manufacture of the diamond-like carbon film in the same manner as Example 1, except that the gas conditions were different from those of Example 1, and other process parameters and procedures were similar to Example 1. Hydrogen introduced at various proportions was employed to control the density of the flake-shaped structure of the diamond-like carbon film.

The proportions of gases in Examples 2-6 are listed in Table 1.

	TABLE 1
	Argon	Methane	Hydrogen
	Example 2	8	8	8
	Example 3	10	5	5
	Example 4	10	5	2
	Example 5	16	8	0
	Example 6	16	4	0

FIG. 3 is the Raman spectrum of the diamond-like carbon film prepared in Examples 2 to 6. Referring to FIG. 3, the diamond-like carbon film prepared in the present invention was composed of SP³ 3-D structure and SP² planar structure, and consequently had a 1332 cm⁻¹ absorption peak of a tetrahedral diamond structure, and a 1580 cm⁻¹ absorption peak of a planar graphite structure.

In sum, a diamond-like carbon film having a flake-shaped structure in a micrometer scale can be prepared by the method of the present invention. Due to the high aspect ratio of the micrometer-scale flake-shaped structure, the film can serve as an especially suitable material for electron emission, and can be applied to cold-cathode emission sources such as field emission components, field emission displays or planar light sources.

Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.

Claims

1. A method for manufacturing diamond-like carbon films, the steps comprising: (a) fixing a substrate in a reaction chamber;(b) pumping the pressure of the reaction chamber below 10-6 torr;(c) introducing at least a carbon-containing gas into the reaction chamber; and(d) depositing a diamond-like carbon film on the substrate by sputtering a graphite target,wherein the deposited DLC film is in a shape of flakes, and the flake-shaped structure of the diamond-like film is arranged on the surface of the substrate in a rose-like shape.

2. The method of claim 1, wherein the introduced gases introduced in step (c) further comprise hydrogen, inert gases, or the combination thereof.

3. The method of claim 2, wherein the ratio of inert gas carbon-containing gas:hydrogen is 5-20:1-10:0-10.

4. The method of claim 1, wherein the introduced carbon-containing gas is a hydrocarbon gas.

5. The method of claim 4, wherein the hydrocarbon gas is methane or acetylene.

6. The method of claim 2, wherein the inert gas is argon gas.

7. The method of claim 1, further comprising heating the substrate to 350° C.-600° C. before sputtering in step (d).

8. The method of claim 1, further comprising heating the substrate to 400° C.-550° C. before sputtering in step (d).

9. The method of claim 1, wherein the material of the substrate is semiconductor or glass.

10. The method of claim 1, wherein the lateral height of the flake-shaped structure is 0.5 μm˜5.0 μm.

11. The method of claim 1, wherein the lateral height of the flake-shaped structure is 0.9 μm˜2.0 μm.

12. The method of claim 1, wherein the thickness of the flake-shaped structure is 0.005 μm to 0.1 μm.

13. The method of claim 1, wherein the thickness of the flake-shaped structure is 0.005 μm to 0.05 μm.

14. The method of claim 1, wherein the flake-shaped structure is in a curved-strip shape or a long-strip shape.

15. The method of claim 1, wherein the surface of the substrate further comprises a conductive layer which is sandwiched between the substrate and the diamond-like film.

16. The method of claim 1, wherein the material of the conductive layer is tin oxide, zinc oxide, tin zinc oxide, metal or alloy.

17. The method of claim 1, wherein power in the sputtering of step (b) process is lower than 200 watts.

18. The method of claim 1, wherein power in the sputtering of step (b) process is lower than 150 watts.

19. The method of claim 1, wherein the pressure of the reaction chamber is 1×10−3˜20×10−3 torr during sputtering.