阅读说明：本技术 一种金刚石膜生长方法、具有金刚石膜的硅片与应用 (Diamond film growth method, silicon wafer with diamond film and application ) 是由 杨国永 江南 于 2020-05-06 设计创作，主要内容包括：本申请公开了一种金刚石膜生长方法、具有金刚石膜的硅片与应用,所述生长方法包括将硅片浸泡在金刚石粉分散液中,得到预处理后的硅片,其中,所述硅片的一面设有由沟槽形成的图形；对所述预处理后的硅片进行热丝化学气相沉积,得到具有金刚石膜的硅片,所述金刚石膜覆盖所述沟槽的底部和侧壁。该方法克服了在较窄较深沟槽内金刚石难形核、难生长问题,避免了沟槽底部及侧壁无法完好成膜导致的绝缘效应无法保证的问题；该方法尤其适合对带有宽16～50μm、深1～180μm沟槽的硅片进行成膜。(The application discloses a diamond film growth method, a silicon wafer with a diamond film and an application, wherein the growth method comprises the steps of soaking the silicon wafer in diamond powder dispersion liquid to obtain a pretreated silicon wafer, wherein one surface of the silicon wafer is provided with a pattern formed by grooves; and carrying out hot wire chemical vapor deposition on the pretreated silicon wafer to obtain the silicon wafer with the diamond film, wherein the diamond film covers the bottom and the side wall of the groove. The method solves the problems that the diamond in the narrower deep groove is difficult to nucleate and grow, and the problem that the insulation effect cannot be ensured due to the fact that the bottom and the side wall of the groove cannot be formed into a film perfectly is solved; the method is particularly suitable for forming a film on a silicon wafer with a groove with the width of 16-50 mu m and the depth of 1-180 mu m.)

1. A diamond film growth method is characterized by at least comprising the following steps:

(1) soaking a silicon wafer in diamond powder dispersion liquid to obtain a pretreated silicon wafer, wherein one surface of the silicon wafer is provided with a pattern formed by a groove;

(2) carrying out hot filament chemical vapor deposition on the pretreated silicon wafer to obtain a silicon wafer with a diamond film, wherein the diamond film covers the bottom and the side wall of the groove;

wherein, the hot wire chemical vapor deposition comprises the following specific conditions:

the number of the heating wires is 8-10, and the power of each heating wire is 700-1100W;

the gas source is H₂And CH₄In which H is₂The flow rate of (1) is 200-400 sccm, CH₄The flow rate of (a) is 1-8% of the hydrogen gas.

2. The method for growing a diamond film according to claim 1, wherein the diamond powder in the diamond powder dispersion liquid in the step (1) has a particle size of 50 to 100 nm.

3. The method for growing a diamond film according to claim 1, wherein the content of diamond powder in the diamond powder dispersion is 0.001 to 0.05 g/mL.

4. The method for growing a diamond film according to claim 1, wherein the solvent in the diamond powder dispersion in the step (1) is a volatile organic solvent;

the volatile organic solvent is selected from ethanol.

5. The diamond film growth method according to claim 1, wherein the step (1) specifically comprises:

(1-a) adding diamond powder into a volatile organic solvent, and ultrasonically dispersing for 5-10 min to obtain a diamond powder dispersion liquid;

and (1-b) adding the silicon wafer into the diamond powder dispersion liquid provided in the step (1-a) and soaking for 1-3 hours to obtain the pretreated silicon wafer.

6. The diamond film growth method according to claim 5, wherein the step (1-b) specifically comprises:

and (2) adding the silicon wafer into the diamond powder dispersion liquid provided in the step (1-a), soaking for 15-20 min, taking out, carrying out ultrasonic treatment on the diamond powder dispersion liquid again for 5-10 min, adding the taken-out silicon wafer, continuing to soak for 15-20 min, and repeating for 3-5 times.

7. The method for growing a diamond film according to claim 1, wherein the specific conditions of the hot-wire chemical vapor deposition in the step (2) further comprise:

the diameter of the monofilament is 0.1-0.7 mm;

the distance between the silicon chip and the heating wire is 5-15 mm;

the working pressure is 1-3 Kpa;

the working temperature is 700-1000 ℃;

the reaction time is 10-30 h;

preferably, the specific conditions of the hot wire chemical vapor deposition include:

the number of the heating wires is 8-10, the diameter of each monofilament is 0.1-0.7 mm, and the power of each monofilament is 870-890W;

the distance between the silicon chip and the heating wire is 8-15 mm;

the gas source is H₂And CH₄In which H is₂The flow rate of (1) is 200-250 sccm, CH₄The flow of (a) is 6-7.5% of the hydrogen;

the working pressure is 2-2.5 Kpa;

the working temperature is 850-890 ℃;

the reaction time is 25-30 h.

8. The method for growing a diamond film according to claim 1, wherein the width of the groove is 16 to 50 μm, and the depth of the groove is 1 to 180 μm.

9. A silicon wafer having a diamond film, which is produced by the diamond film growth method according to any one of claims 1 to 8.

10. The application of the silicon wafer with the diamond film prepared by the diamond film growth method according to any one of claims 1 to 8 in the fields of micromachines, microelectronics, microsensors and micro-opto-electromechanical systems.

Technical Field

The application relates to a diamond film growth method, a silicon wafer with a diamond film and an application, and belongs to the field of diamond materials.

Background

Diamond, as a special crystal structure, has a plurality of excellent properties such as high hardness, wear resistance, corrosion resistance, high melting point, wide band gap, high light transmittance, excellent physical and chemical stability, very good insulating property and the like, and has wide application in the fields of machining, marine dynamic sealing, micro-electro-mechanical systems, field emission, optical windows, electrochemistry, acoustics, biomedicine and the like.

The hot filament CVD has the advantages of simple device, good process controllability, easy realization of large-area deposition, lower preparation cost and the like, and becomes the most widely applied diamond film preparation technology at present.

With the development of microelectronic technology, various integrated patterns are manufactured on a silicon wafer, and the silicon wafer with the patterned diamond film can be used as devices such as microelectronics, microsensors and the like. For example, grooves are arranged on a silicon wafer according to a pattern, and a diamond coating is grown in the grooves to reach the insulation effect value of continuous film maintenance.

When the width of a silicon chip groove is narrow (less than 50 mu m) and the depth is too deep (more than 100 mu m), a temperature field film layer or particles are difficult to enter the groove in the existing hot wire CVD process, and with the reduction of energy or reaching a threshold value, films are difficult to form on the side wall and the bottom of the groove, so that the requirement of an insulation effect cannot be met.

Disclosure of Invention

According to the first aspect of the application, a diamond film growth method is provided, the method overcomes the problems that diamond in a narrow and deep groove is difficult to nucleate and grow, and the problem that the insulation effect cannot be ensured due to the fact that the bottom and the side wall of the groove cannot be formed into a film perfectly is avoided; the method is particularly suitable for forming a film on a silicon wafer with a groove with the width of 16-50 mu m and the depth of 1-180 mu m.

A diamond film growth method at least comprises the following steps:

(1) soaking a silicon wafer in diamond powder dispersion liquid to obtain a pretreated silicon wafer, wherein one surface of the silicon wafer is provided with a pattern formed by a groove;

(2) carrying out hot filament chemical vapor deposition on the pretreated silicon wafer to obtain a silicon wafer with a diamond film, wherein the diamond film covers the bottom and the side wall of the groove;

wherein, the hot wire chemical vapor deposition comprises the following specific conditions:

the number of the heating wires is 8-10, and the power of each heating wire is 700-1100W;

the gas source is H₂And CH₄In which H is₂The flow rate of (1) is 200-400 sccm, CH₄The flow rate of (a) is 1-8% of the hydrogen gas.

In the embodiment of the application, the groove is formed on the surface of the silicon wafer through a patterning process, the section of the groove can be U-shaped, rectangular and the like, and the U-shaped is preferred without limitation in the application.

Optionally, the particle size of diamond powder in the diamond powder dispersion liquid in the step (1) is 50-100 nm;

the content of diamond powder in the diamond powder dispersion liquid is 0.001-0.05 g/mL, preferably 0.01-0.03 g/mL.

The inventor finds that when the diamond particle size and the content of the diamond in the dispersion meet the requirements, the diamond powder can smoothly enter the groove and can be uniformly diffused in the groove, and favorable conditions are provided for nucleation to ensure the uniformity of film formation.

Optionally, the solvent in the diamond powder dispersion liquid in the step (1) is a volatile organic solvent;

the volatile organic solvent is selected from ethanol.

Optionally, step (1) specifically includes:

(1-a) adding diamond powder into a volatile organic solvent, and ultrasonically dispersing for 5-10 min to obtain a diamond powder dispersion liquid;

and (1-b) adding the silicon wafer into the diamond powder dispersion liquid provided in the step (1-a) and soaking for 1-3 hours to obtain the pretreated silicon wafer.

Optionally, the step (1-b) specifically includes:

and (2) adding the silicon wafer into the diamond powder dispersion liquid provided in the step (1-a), soaking for 15-20 min, taking out, carrying out ultrasonic treatment on the diamond powder dispersion liquid again for 5-10 min, adding the taken-out silicon wafer, continuing to soak for 15-20 min, and repeating for 3-5 times.

Because the opening of the groove is narrower and deeper, the problem that diamond powder cannot be immersed into the bottom of the groove due to the change of the density of the dispersed liquid can be prevented when the groove is immersed in the above mode, the nucleation density is further improved, and the uniformity of surface nucleation is also ensured.

Optionally, the specific conditions of the hot-wire chemical vapor deposition in the step (2) further include:

the diameter of the monofilament is 0.1-0.7 mm;

the distance between the silicon chip and the heating wire is 5-15 mm;

the working pressure is 1-3 Kpa;

the working temperature is 700-1000 ℃;

the reaction time is 10-30 h;

preferably, the specific conditions of the hot wire chemical vapor deposition include:

the number of the heating wires is 8-10, the diameter of each single wire is 0.1-0.7 mm, the power of each single wire is 700-1100W, and 750-950 ℃ is preferred;

the distance between the silicon chip and the heating wire is 5-15 mm;

the gas source is H₂And CH₄In which H is₂The flow rate of (1) is 200-400 sccm, CH₄The flow of (a) is 1-8% of the hydrogen;

the working pressure is 1-3 Kpa;

the working temperature is 700-1100 ℃, and preferably 750-1000 ℃;

the reaction time is 10-30 h.

Optionally, the width of the groove is 16-50 μm, preferably 16-30 μm; the depth of the groove is 1-180 mu m.

Optionally, the hot-wire chemical vapor deposition in the step (2) includes:

the number of the heating wires is 8-10, the diameter of each monofilament is 0.1-0.7 mm, and the power of each monofilament is 870-890W; the heating wire is preferably a tantalum wire;

the distance between the silicon chip and the heating wire is 8-15 mm;

the gas source is H₂And CH₄Mixed gas of (2), whichMiddle H₂The flow rate of (1) is 200-250 sccm, CH₄The flow of (a) is 6-7.5% of the hydrogen;

the working pressure is 2-2.5 Kpa;

the working temperature is 850-890 ℃; optionally, the temperature of the silicon wafer is increased by padding the silicon wafer under the silicon wafer; preferably, 2 quartz plates with a thickness of 15mm are laid on the mat.

The reaction time is 25-30 h.

The gas flow reflects the update rate of various indoor components, in the diamond film forming process, when the carbon content in the source gas proportion is larger, the non-diamond carbon content of the diamond film is too much, when the carbon content in the source gas proportion is smaller, the nucleation of diamond on the silicon wafer is too little, the diamond film is not easy to generate, when the temperature of the silicon wafer is higher, isolated diamond particles are easy to generate on the silicon wafer, and the diamond film is not easy to form.

In a second aspect of the present application, there is provided a silicon wafer with a diamond film prepared by the diamond film growth method described in any one of the above.

In a third aspect of the present application, there is provided an application of the silicon wafer with a diamond film prepared by the diamond film growth method described in any one of the above in the fields of micromachines, microelectronics, microsensors, and micro-opto-electromechanical systems.

The beneficial effects that this application can produce include:

according to the diamond coating growth method provided by the application, the nucleation density in the film nucleation stage is greatly improved by immersing diamond powder in the pretreatment step, the nucleation density is improved and the uniformity of surface nucleation is ensured by controlling the parameters of the hot wire treatment process, so that the problem that nucleation is difficult to grow in a narrow and deep groove is solved, and the problem that the insulation effect cannot be ensured due to the fact that the bottom and the side wall of the groove cannot be formed into a film perfectly is solved; the method is particularly suitable for forming a film on a silicon wafer with a groove with the width of 16-50 mu m and the depth of 1-180 mu m.

Drawings

FIG. 1 is a Raman spectrum of a silicon wafer having a diamond film provided in example 1;

FIG. 2 is an electron micrograph of a silicon wafer having a diamond film provided in example 1, wherein FIG. 2a is a sectional view showing a trench position, and FIG. 2b is a partially enlarged sectional view of a trench;

FIG. 3 is an electron micrograph of a silicon wafer having a diamond film provided in comparative example 1, wherein FIG. 3a is a sectional view of a trench bottom position and FIG. 3b is a top view of the trench position;

FIG. 4 is an electron micrograph of a silicon wafer having a diamond film provided in comparative example 2, wherein FIG. 4a is a top view of the bottom of a trench and FIG. 4b is a cross-sectional view of the trench position;

fig. 5 is an electron micrograph of a silicon wafer having a diamond film provided in comparative example 3, in which fig. 5a is a sectional view of a trench opening position and fig. 5b is a sectional view of a trench bottom position.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

The hot wire chemical vapor deposition equipment used in the method is HF-650 model provided by Beijing Taikono company;

the application obtains an electron microscope scanning image through an EVO18 model large cavity scanning electron microscope (SEM4) device provided by Germany ZEISS company;

the raman spectra were measured using a Renishaw inVia Reflex model confocal micro raman spectrometer (Renishaw) instrument from Renishaw corporation.

Example 1 preparation of silicon wafer having Diamond film

i) Pretreatment: adding diamond powder with the particle size of 50-100 nanometers into ethanol, and performing ultrasonic treatment for 10min at the ratio of 2.0g/100ml to obtain diamond powder dispersion liquid; and (3) soaking the silicon wafer in the diamond dispersion liquid for 20min, then taking out, ultrasonically treating the dispersion liquid for 10min again, continuously soaking the silicon wafer taken out for 20min, repeating the ultrasonic-soaking process for 4 times, and then finishing treatment to obtain the pretreated silicon wafer, wherein the silicon wafer is subjected to graphical treatment, and the surface of the silicon wafer is provided with a U-shaped groove with the opening width of 16 microns and the depth of 180 microns.

ii) chamber cleaning: the interior of the cavity of the hot wire chemical vapor deposition equipment is cleaned by using dust-free cloth and absolute ethyl alcohol.

iii) a substrate: and (3) filling a quartz plate with thickness of 15mm and thickness of 2 mm into the sample table to serve as a substrate so as to increase the temperature of the sample, binding 8 tantalum wires with the diameter of 0.35mm, keeping the distance between the silicon plate and the tantalum wires to be 8 mm (hereinafter referred to as wire distance), and vacuumizing the cavity to be lower than 0.01 Pa.

iiii) growth: growing a diamond film on the surface of the pretreated silicon wafer by hot wire chemical vapor deposition equipment to obtain the silicon wafer with the diamond film, wherein the specific conditions are as follows:

with H₂And CH₄As a reaction gas (gas source), wherein H₂Flow rate of (2) 200sccm, CH₄The flow rate of (1) is 6% of the hydrogen flow rate in the first half hour of the reaction, the subsequent time is 7.5% of the hydrogen flow rate, the working pressure is 2.3Kpa, the working temperature is 870 ℃, the monofilament power of the hot filament chemical vapor deposition device is 880W, and the reaction time is 30 h.

Comparative example 1

The preparation method is basically the same as that of example 1, except that:

tantalum wires with 7 wires and wire spacing of 10mm, and CH after reaction for half an hour₄Flow rate of H₂5.5% of the flow, 900W of filament power, 2.5pa of air pressure and 910 ℃ of working temperature.

Comparative example 2

The preparation method is basically the same as that of example 1, except that:

tantalum wire 7, CH after half an hour of reaction₄Flow rate of H₂5.5% of the flow, 860W of the filament power and 860 ℃ of the working temperature.

Comparative example 3

The preparation method is basically the same as that of example 1, except that:

7 tantalum wires, 900W of single wire power and 850 ℃ of working temperature.

Characterization of the diamond films provided in the examples:

the raman spectra were measured using a confocal micro raman spectrometer (Renishaw) instrument from Renishaw inc, model Renishaw inVia Reflex. The raman spectrometer was tested as shown in fig. 1 and as can be seen in fig. 5: the total number of Raman peaks of the diamond thick film is 6, and the Raman peaks are sequentially at 1134, 1192, 1332, 1350, 1470 and 1550cm^-1Here, in the typical nanocrystalline diamond raman spectrum, it can be seen that example 1 gives a diamond film.

An electron microscope scan of a silicon wafer with a diamond film was obtained by an EVO18 model large cavity scanning electron microscope (SEM4) apparatus supplied by ZEISS, germany. As shown in fig. 2, the diamond film provided in example 1 grows uniformly on the sidewall and bottom of the trench; as shown in FIG. 3, in comparative example 1, only a part of diamond particles were formed on the surface of the silicon wafer, and the bottom and the side walls in the groove were substantially free from nucleation; as shown in FIG. 4, in comparative example 2, the bottom and the side walls in the groove had only a part of diamond particles, but no film was formed; as shown in FIG. 5, in comparative example 3, the diamond continuous film was formed on the side walls of the groove, but the film was not formed in most of the region of the bottom of the groove.

A conclusion is drawn;

in the film forming process, because the groove is specially designed and processed, heat source and carbon source active particles generated by the hot wire are difficult to enter the groove to cause internal nucleation to be hindered to a certain degree, and certain nucleation density can be increased by diamond powder intake in cooperation with power, air pressure and H₂And CH₄The ratio value enables the active ions to reach the optimal adsorption value, and the optimal growth value is finally obtained.

TABLE 1 table of process parameters and results for examples and comparative examples

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.