CN1782123A - Diamond-like carbon film and preparation method thereof - Google Patents

Abstract

The invention provides a diamond-like carbon film which is wear-resistant, can be formed by a low-temperature process and has high adhesion and a manufacturing method thereof. Finally, a surface layer which is substantially made of the diamond-like carbon material is deposited and plated on the middle layer by taking the hydrogen-containing carbon source as the film so as to form the diamond-like carbon film with high adhesive force. The diamond-like carbon film provides proper hardness/toughness ratio, so that the intermediate layer has enough mechanical supporting force, and the diamond-like carbon material with high hardness is attached to the base material and is not easy to fall off.

Description

Diamond-like carbon film and preparation method thereof

technical field

The present invention relates to a kind of high adhesion diamond-like carbon (Diamond-Like Carbon, DLC) thin film and preparation method thereof, especially a kind of diamond-like carbon thin film coated on the base material by plasma thin film deposition method and its formation Methods.

Background technique

Diamond-like carbon (DLC) film has the characteristics of high hardness, corrosion resistance, smooth surface, small friction coefficient, high film density, good electrical insulation, good thermal conductivity, good biocompatibility, and can grow at low temperature. Therefore, diamond-like carbon films can be applied in molds, cutting tools, optical components, electronic components, surface coatings and biomedical materials.

Generally speaking, the formation of diamond-like carbon film is to accelerate the hydrocarbon ions (CH _x ⁺ ) generated in the plasma and penetrate into the surface of the substrate to form a film with high hardness, wear resistance and deep industrial application value. However, there is a compressive stress in the film, which affects the ability of the diamond-like carbon material to adhere to the substrate.

In order to solve this problem, the industry generally adds an intermediate layer between the substrate and the diamond-like carbon film, such as titanium nitride, titanium carbide, (multilayer coating) to form a multilayer intermediate layer by multilayer coating , as a barrier layer for dislocation movement, the use of the film interface can generate energy deflection and release residual stress to improve surface adhesion. However, this method needs to properly control the hardness/toughness ratio of the multilayer film combination. If the hardness is too high and the adhesion is insufficient, it will not be resistant to impact; if the toughness is too high, although the impact resistance is good, but the hardness is not enough, it will not be resistant to wear. And other issues. Furthermore, titanium nitride and titanium carbide belong to high-temperature process (operating temperature is about 450°C), while the coating of diamond-like carbon material is a low-temperature process. It is necessary to wait for the temperature of the intermediate layer to drop before coating the diamond-like carbon material; When the temperature rises and falls, it not only causes waste of time and energy, but also generates thermal stress that affects the adhesion of the diamond-like carbon film.

In addition, titanium nitride and titanium carbide are less protective in acidic or alkaline environments, so it is necessary to provide a diamond-like carbon with high adhesion, wear resistance, low temperature process, and good chemical inertness in the middle layer. film.

Contents of the invention

The main purpose of the present invention is to provide a high-adhesion diamond-like carbon film that is wear-resistant, can be formed by a low-temperature process, and has an intermediate layer with good chemical inertness.

According to the present invention, it is mainly to use organosiloxane compound, such as hexamethyldisiloxane (HMDSO) mixed with hydrogen-containing carbon source, to continuously change the ratio of organosiloxane compound in the method of film deposition, on the substrate A progressive intermediate layer is formed. The intermediate layer is composed of silicon-oxygen functional groups (Si-O-Si) dispersed in the diamond-like carbon material at molecular level, and the density of the silicon-oxygen functional groups gradually changes along the thickness of the intermediate layer. Finally, a surface layer substantially made of diamond-like carbon material is deposited and plated on the middle layer by using a hydrogen-containing carbon source as a film, so as to form a diamond-like carbon film with high adhesion.

The present invention firstly provides a diamond-like carbon film, comprising at least:

a substrate;

An intermediate layer, located on the substrate, the intermediate layer has at least silicon oxide material; and

A surface layer is located above the middle layer.

The intermediate layer may include a single-layer structure, a multi-layer structure or a progressive layer structure. The intermediate layer is formed by mixing a silicon-oxygen material into a diamond-like carbon material, and the silicon-oxygen material includes silicon oxide or a material containing silicon-oxygen functional groups. The distribution density of the silicon-oxygen functional groups gradually changes with the thickness of the silicon-oxygen intermediate layer.

Simultaneously, the present invention also provides the manufacture method of diamond-like carbon film, comprises at least:

providing a substrate;

forming an intermediate layer on the substrate, the intermediate layer has at least silicon-oxygen material; and

A surface layer is formed on the middle layer.

The method for forming an intermediate layer further includes: forming a diamond-like carbon material on the substrate, and mixing a silicon-oxygen material into the diamond-like carbon material; or, forming a silicon-oxygen material on the substrate, and mixing A diamond-like carbon material is in the silicon-oxygen material.

According to a specific embodiment of the present invention, the method for forming an intermediate layer may further include:

Mixing and feeding an organosiloxane compound and a hydrogen-containing carbon source to perform a deposition process;

The ratio of the organosiloxane to the hydrogen-containing carbon source is gradually changed.

In the present invention, the hydrogen-containing carbon source may be one or more selected from the group consisting of methane, ethane, acetylene, ethylene, and benzene.

In the diamond-like carbon thin film process, the invention provides an intermediate layer of a low-temperature process. Since the process temperature of the surface layer of diamond-like carbon material is lower than the high-temperature process of traditional technology, the low-temperature process intermediate layer of the present invention not only saves the cooling time and heat consumption of the surface layer of diamond-like carbon material, but also provides suitable hardness. /Toughness ratio, so that the middle layer has sufficient mechanical support, and the surface layer of high hardness diamond-like carbon material can be attached to the substrate and is not easy to fall off. The hardness test has confirmed that under appropriate conditions, the critical load is greater than 50 Newtons, and the hardness can reach 21.75×109 Pa (Pa).

The invention also conducts thermal stress experiment and stability test for the diamond-like carbon film with high adhesion. It shows that the adhesion and hardness of the diamond-like carbon film of the present invention are not affected by thermal stress. The structure will not change in the environment with a temperature as high as 400 ℃.

From the test results described above, it can be confirmed that the diamond-like carbon film provided by the present invention has the technical advantages of high adhesion, wear resistance, can be formed by a low-temperature process, and the intermediate layer has good chemical inertness.

Description of drawings

FIG. 1 is a schematic diagram illustrating an operating system of a plasma ion evaporation process.

FIG. 2 is a schematic diagram showing progressive layer decomposition of a diamond-like carbon film formed on a steel substrate according to a preferred embodiment of the present invention.

Fig. 3 is a Raman spectrum analysis diagram drawn according to the stability test of the present invention.

A brief description of the symbols in the figure:

10 base material 20 silicon-oxygen intermediate layer 30 diamond-like carbon layer

Detailed ways

According to a preferred embodiment of the present invention, the diamond-like carbon film with high adhesion includes an intermediate layer containing silicon oxide and a surface layer substantially made of diamond-like carbon material formed on a metal or non-metallic solid substrate.

The intermediate layer has silicon oxide (Si-O-Si) functional groups. The silicon-oxygen functional group is a curved structure centered on oxygen, which contributes to the stress absorption of the diamond-like carbon film itself, so as to enhance the adhesion of the surface layer of the diamond-like carbon material. In some embodiments, the surface layer of the diamond-like carbon material can be closely combined with the substrates such as steel, tungsten steel, nickel, chromium, and aluminum. According to some embodiments of the present invention, the intermediate layer may be a single-layer structure, a multi-layer structure or a progressive layer structure, but is preferably a progressive layer structure.

For the formation of the intermediate layer, firstly, the organosiloxane compound is mixed with a hydrogen-containing carbon source into the reactor, and a gradual layer is formed on the substrate through a thin film deposition process, and the properties between the layers will not change drastically. , gradually changing the proportion of organosiloxane compounds in the process to control the distribution density of silicon-oxygen functional groups (Si-O-Si).

In a preferred embodiment of the present invention, the unit chemical formula of organosiloxane compound, such as hexamethyldisiloxane (HMDSO) is (CH ₃ ) ₃ SiOSi(CH ₃ ) ₃ , and the hydrogen-containing carbon source is methane. The film deposition process used includes chemical vapor deposition, ion evaporation or sputtering, preferably plasma ion evaporation process. FIG. 1 illustrates the operating system used in the plasma ion evaporation process. In this preferred embodiment, the substrate carrier is connected to a high-frequency power supply, and then a capacitive discharge is generated with the wall of the vacuum chamber of the reactor to dissociate the working gas (HMDSO and methane), and its ions are driven by the high-frequency self-bias ( self bias) get energy to directly bombard the substrate. The process pressure is maintained at 1.9×10 ^-2 Torr, and the high frequency power is 100W. The plasma ion evaporation process of the working gas (HMDSO and methane) is a low-temperature process, and the operating temperature is less than 300°C.

In this preferred embodiment, the ratio of organosiloxane compound (HMDSO) to methane ranges from 32% to 0.1%, gradually changing along the thickness of the deposit. FIG. 2 shows a schematic diagram of progressive layer decomposition of a diamond-like carbon film formed on a steel substrate according to a preferred embodiment of the present invention, showing the ratio distribution of organosiloxane compound (HMDSO) and methane. In this preferred embodiment, the proportion gradient of the organosiloxane compound (HMDSO) on the steel substrate 10 decreases from a maximum of 32% to 0.1% along the thickness of the silicon-oxygen intermediate layer 20, and the thickness of the intermediate layer ranges from Between 1.2 μm and 3 μm. In another embodiment of the present invention, the method for forming the intermediate layer further includes, for example, firstly forming a diamond-like carbon material on a substrate, and then doping silicon-oxygen material into the diamond-like carbon material. In yet another embodiment of the present invention, the method for forming the intermediate layer further includes, for example, firstly forming a silicon-oxygen material on a substrate, and then doping a diamond-like carbon material into the silicon-oxygen material.

Finally, a diamond-like carbon layer 30 is formed on the middle layer to form a diamond-like carbon film with high adhesion. The diamond carbon layer 30 is composed of diamond-like carbon material; the diamond-like carbon layer 30 is formed by passing a 100% hydrogen-containing carbon source into a reactor through a film deposition process. In this preferred embodiment, the hydrogen-containing carbon source is methane, and the film deposition process used includes chemical vapor deposition, ion evaporation or sputtering, preferably plasma ion evaporation process. The thin film deposition process also connects the substrate carrier to a high-frequency power source, so that the vacuum chamber wall of the reactor generates capacitive discharge plasma methane dissociation, so that the energy obtained by the high-frequency self bias (self bias) of methane ions can be directly Bombard the substrate. The process pressure is maintained at 1.9×10 ^-2 Torr, and the high frequency power is 100W. A preferred thickness of the diamond-like carbon layer ranges from 0.1 μm to 0.5 μm.

In order to prove that the diamond-like carbon film provided by the present invention has the characteristics of high adhesion, high hardness, and wear resistance, the present invention conducts thermal stress experiments and stability tests on the diamond-like carbon film with high adhesion.

The thermal stress test is to place the diamond-like carbon film provided by the present invention in an oven, the temperature is controlled at room temperature and 400°C respectively and maintained for 20 minutes, and the cycle is repeated 50 times; then the microhardness measurement and scratch test are carried out. Observing the scratch test results under an optical microscope, when the diamond head was loaded with a load of 50 Newtons, the diamond-like carbon film was still well attached to the substrate. Observing the hardness measurement results under an atomic force microscope (AFM) also found that the hardness value did not decrease. , showing that the diamond-like carbon film of the present invention is not affected by thermal stress.

The stability test is to maintain the diamond-like carbon film provided by the present invention in an environment with a temperature of 400° C. for 2 hours, and then perform Raman spectroscopic analysis. Fig. 3 is according to the Raman spectrum analysis figure drawn by the stability test of the present invention, two absorption spectra before and after the test in the figure have absorption peaks at wavenumber 1500 and 3750 respectively, and the absorption wavelength of expression spectrum does not change; Show The structure of the high-adhesion diamond-like carbon film did not change in this environment (structural graphitization).

Although traditional intermediate layer materials, such as titanium nitride and titanium carbide, can withstand higher temperatures, the intermediate layer of the diamond-like carbon film provided by the present invention is composed of silicon oxide and diamond-like carbon materials. Excellent chemical inertness in aggressive environments.

According to the above description, it can be confirmed that the diamond-like carbon film provided by the present invention has the technical advantages of high adhesion, high hardness, wear resistance, low temperature process, and good chemical inertness of the intermediate layer.

Although the above-mentioned embodiments have described the technical characteristics and advantages of the present invention in detail, it is worth noting that any modifications and changes that do not exceed the scope of the present invention are still included in the protection scope of the present invention, for example, the present invention The diamond-like carbon film structure can be a multilayer structure having at least an intermediate layer and a surface layer, and is not limited to the scope disclosed in the above-mentioned embodiments; the above-mentioned embodiments are only used to illustrate the content of the present invention. It is not intended to limit the scope of the present invention, and the scope of protection of the present invention should be determined by the claims.

Claims (14)

1. A diamond-like carbon film, comprising at least: a substrate; An intermediate layer, located on the substrate, the intermediate layer has at least silicon oxide material; and A surface layer is located above the middle layer. 2. The diamond-like carbon film according to claim 1, wherein the intermediate layer comprises a single-layer structure, a multi-layer structure or a progressive layer structure. 3. The diamond-like carbon film according to claim 2, wherein the surface layer further comprises a type of diamond-like carbon material. 4. The diamond-like carbon film according to claim 3, wherein the intermediate layer is formed by mixing silicon-oxygen material into diamond-like carbon material. 5. The diamond-like carbon film as claimed in claim 4, wherein the silicon-oxygen material comprises silicon oxide or a material containing silicon-oxygen functional groups. 6. The diamond-like carbon film as claimed in claim 5, wherein the distribution density of the silicon-oxygen functional groups changes gradually with the thickness of the silicon-oxygen interlayer. 7. A method for manufacturing a diamond-like carbon film, comprising at least: providing a substrate; forming an intermediate layer on the substrate, the intermediate layer has at least silicon-oxygen material; and A surface layer is formed on the middle layer. 8. the manufacture method of diamond-like carbon thin film as claimed in claim 7, wherein the method for forming intermediate layer also comprises: forming a diamond-like carbon material on the substrate; and Mixed with silicon-oxygen material in diamond-like carbon material. 9. the manufacture method of diamond-like carbon film as claimed in claim 7, wherein the method for forming intermediate layer also comprises: forming a silicon oxide material on the substrate; and A diamond-like carbon material is mixed into the silicon-oxygen material. 10. the manufacture method of diamond-like carbon film as claimed in claim 7, wherein the method for forming intermediate layer also comprises: Mixing and feeding an organosiloxane compound and a hydrogen-containing carbon source to perform a deposition process; The ratio of the organosiloxane to the hydrogen-containing carbon source is gradually changed. 11. The method for manufacturing a diamond-like carbon film according to claim 10, wherein the organosiloxane compound includes a compound having a unit chemical formula (CH ₃ ) ₃ SiOSi(CH ₃ ) ₃ . 12. the manufacture method of diamond-like carbon thin film as claimed in claim 7, wherein the formation method of said surface layer, comprises: A hydrogen-containing carbon source is introduced; A thin film deposition process is performed. 13. The method for manufacturing a diamond-like carbon film according to claim 12, wherein the operating temperature of the film deposition process is less than 300°C. 14. The method for producing a diamond-like carbon film according to claim 10 or 13, wherein the hydrogen-containing carbon source is selected from one or more of methane, ethane, acetylene, ethylene or benzene.