JPS6240375A - Hard carbon film - Google Patents

Abstract

PURPOSE:To increase deposition speed and to form a carbon film having high hardness by depositing the hard carbon film contg. a specific ratio of fluorine by a plasma CVD method on a substrate. CONSTITUTION:A gaseous mixture in which a hydrocarbon compd. such as CH4 or C2H4 and gaseous fluoring-contg. compd. such as CF4 or CF2H2 and if necessary, a diluting gas such as H2 are made to exist mixedly is used and the hard carbon film is deposited on the substrate. C:F in the gaseous mixture is required to be 100:1-3:8 and the DC plasma CVD method, RF plasma CVD method, etc. are used. The substrate is installed to a cathode and about -300--1kV voltage is impressed and DC of about 50mA-2A DC current density is discharged. The carbon film having 0.1-30atom% fluorine, about 50-98atom% carbon and about 0.1-30atom% hydrogen is obtd. The hardness thereof is >=500 surface Vickers hardness. This hard carbon film can contain <=20atom% silicon.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a hard carbon membrane.

[Prior Art] Recently, a highly hard carbon film called a diamond-like carbon film has been formed by ion beam evaporation, ion beam sputtering, sputtering, CVD, plasma CVD, etc., and is used for surface hardening of cutting blades. It is attracting attention as a material, semiconductor, antireflection film for infrared optical components, hard protective film, insulating material, wear-resistant material, etc. (For example, "Electro Ceramics J May 19B5 issue 48-
(See “Hard Carbon Film” on page 54).

For example, when forming a hard carbon film by plasma CVD method, usually CH4, C2H4, C2H2, C4H
Hydrocarbon compounds such as IO, benzene, H2, Ar
, t(e, etc.) is plasma decomposed and deposited on the substrate to form a film.

[Problem to be Solved by the Invention 1] When attempting to form a conventional hard carbon film by the conventional method as described above, the deposition rate is as low as 0.1 to 5 persons/second, and the If the temperature is increased, the hardness decreases, and powder and film adhere to the interior of the chamber other than the electrode portion, causing pinholes and the like, resulting in a decrease in productivity.

The purpose of the present invention is to increase the deposition rate itself, and to form a hard carbon film that does not reduce the hardness of the film even if the deposition rate is increased, and that causes less powder or film to adhere to the inside of the chamber other than the electrode part. It is something to do.

[Means for Solving the Problems] The present invention involves mixing a compound containing fluorine as a constituent in the raw material gas when forming a conventional hard carbon film,
When a film is formed by the plasma CVD method, a hard carbon film can be formed with high productivity at a high deposition rate, and which has the characteristics that not only does the hardness not decrease even when the film is formed at a high deposition rate, but the hardness even increases. This was done based on the discovery that fluorine deposited on a substrate by plasma CVD method was
The present invention relates to a hard carbon film containing 0atll1%.

[Example] There are no particular limitations on the substrate used in the present invention, and plasma C
Any substrate on which a hard carbon film can be formed by the VD method can be used.

A specific example of such a substrate is, for example, No.

Substrates made of metals and alloys such as Cu, 1n, M, 1nSSUS, single crystal silicon, single crystal germanium, GaAs,
Semiconductor substrate such as GaP, SiCz M 203.
Ceramic substrate such as 5i07 or A(1, ■,
Metal substrates surface-treated with metals such as HOIN and Cu,
Examples include semiconductor substrates and ceramic substrates.

The hard carbon film of the present invention contains 0.1 to 30 at of fluorine.
ln%, preferably 1 to 15 atm%, more preferably 1 to 7 atm%, carbon 50 to 98 atIO%,
Preferably 80-95 atm%, hydrogen 0.1-30a
tm%, preferably 1 to 15 atm%,
If necessary, the silicon content is 20 atm % or less, preferably 0.
It may be contained in a range of 0.01 to 5 atm%.

When the fluorine content is less than 1% O, Iatll, the deposition rate, hardness, and the relationship between deposition rate and hardness are almost the same as those of a film containing only carbon or hydrogen without fluorine, and when it exceeds 30 atm%, the film's Peeling begins to occur.

When the carbon content is less than 50 atm %, the film tends to become polymeric and the hardness of the film becomes low, and when it exceeds 98%, the adhesion of the film to the substrate tends to decrease.

Note that the hydrogen content varies depending on the carbon content, fluorine content, film forming conditions, etc., and as long as it is within the above range, there is no problem in terms of high hardness, wear resistance, etc. of the hard carbon film of the present invention.

Furthermore, when silicon is contained within the above range, there is no problem in terms of high hardness, wear resistance, etc. of the hard carbon film of the present invention, especially when a metal substrate such as SUS, #, Cu, etc. is used. This improves the adhesion between the substrate and the hard carbon layer. It has already been proposed (Japanese Patent Application No. 83137/1983) that adding silicon to a hard carbon film that does not contain fluorine improves its adhesion; The same effect can be obtained.

The thickness and hardness of the hard carbon film of the present invention are not particularly limited, but since it is formed by plasma CVD, the film thickness is usually about 10 to 50 μm, and the hardness is generally that of a hard film. The surface Vickers hardness is considered to be within the range of 5.
00 or more, preferably about 1000 or more.

Although there is no particular limitation on the upper limit of hardness, the hardness that can actually be manufactured is 7000 to 8000, which is about the same level to slightly lower than that of diamond.

The hard carbon film of the present invention is produced by plasma CVD as described above.
The film is formed by the method. Specific examples of plasma CVD methods include normal DC plasma CVD method and RF plasma CVD method.
method, microwave plasma CVD method, DC and R
Examples include a plasma CVD method using a mixture of both F and F. Among these, the substrate is installed at the cathode, and the substrate has a
0V ~ -2KV, preferably L < Lt -300V ~-
IKM) Full voltage is applied, OCL current is about 50mA to 28,
Preferably, a film obtained by direct current discharge of a raw material gas at 1 to 2 A has higher hardness and higher electrical resistivity than a film obtained by a normal RF plasma CVD method. Zarani above DC
0.001 to 101II10d1 preferably 15 for discharge
When RF of ~10,100 O/crl is applied and an insulator is formed by a mixed discharge of both, a stable discharge can be obtained and the deposition rate can be increased, making it a more excellent method.

A specific example of the raw material gas is C, which is generally used when forming a hard carbon film by plasma CVD method.
Hydrocarbon compounds such as H4, C2H4, C2H2, C4H1o, benzene, and H2, Ar used if necessary
, CF4 is added to the mixed gas with diluent gas such as He.
, CF2 H2, C2Fa, C2Fs, C6F
Examples include those in which fluorine-containing compound gases such as 6, C, and F3H3 are mixed.

Next, the proportions of the hydrocarbon compound, fluorine-containing compound gas, and any gas used in the raw material gas will be explained.

C in hydrocarbon compounds and fluorine-containing compound gases:
F is 100:1 to 3:8, which increases the deposition rate by 10
It is necessary to increase the fluorine content to 0.1 to 30 atll1% in the formed film, and
The ratio is preferably 20:1 to 1:2. The gas used as necessary is a component used mainly for dilution, pressure adjustment, etc., and may be applied as appropriate.

For example, when forming a hard carbon film using CH4 and CF4.82, H2 is 50SCCH1CH4+ CF
Let a be 40SCCH, change the ratio, I To
DC voltage -600V (DC current 800mA)
) and RF of about 50 W (100 III W/cffl) for about 50 minutes, the film is formed at a deposition rate as shown in FIG. 1, and a film with hardness as shown in FIG. 2 is obtained. In addition, the capacity ratio is CFa / (CH4 + CF4)
is 0. The composition of the film obtained under the above conditions in '3 is:
Approximately H is B atm%, F is 4 atm%, and C is 88
Atm%, the Vickers hardness is approximately 6500.

In the above explanation, the case where C114, CF4, and H2 were used as raw material gases was explained, but CHa
10~50SCCH, C2Fs 5~40SCCH,
A combination such as H2100~500SCCH may also be used,
In addition, the film forming conditions are DC voltage -400V to -1 to V(
Current 200mA~18), RF power 50~200
W (100~400mW/ca!), pressure 0.1~
The hard carbon film of the present invention can be formed under conditions of about 10 Torr.

More precisely, the fluorine content in the hard carbon film of the present invention can be measured by a method such as ESCA, but it can also be measured by an IR absorption spectrum.

In other words, if a C-F bond exists in the membrane, 1o
oo ~ 1350cm'', absorption due to the stretching mode occurs, so it is only necessary to measure this magnitude.This measurement is performed by calculating the oscillator strength of the C-F stretching mode from the IR absorption spectrum as A and Sult, A X / =
d ω (where ω is the wave number where the C-F bond exists, α(C-F
) can be measured as an absolute content using the absorption coefficient at the wave number where the C-F bond exists.
m-', their integrated intensity (f-7;
7 dω) ratio f cos dω /fa(0-H) dω
ω ω(ω
is the wave number, α(C-■ and α(C-F) are each 28
00~3100cm+-1 and rj 1000~135
It is preferable to calculate the absorption due to each existing stretching mode) because it is easier and does not require accurate film thickness when determining the absorption coefficient.

Empirically, when the ratio of the integrated intensities is 0.001 to 100, the fluorine content in the hard carbon film of the present invention is 0.1 to 100.
It is known that it is 30 ati%, and 0.01 to 5
It is preferable that it is 0 because the fluorine content will be 1 to 20 atm%.

Note that the f-hoeing beam dω and the concave beam dω are ω
ωeach C
-F, the wave number at which the C-H stretching mode exists (C-F is 1000 to 1350 cm-', C-H is 2
800 to 3100 cl-').

The hydrogen content and fluorine content according to the IR absorption spectrum in the hard carbon film of the present invention are CFa /
As the ratio of (CH4 + CF4) increases, absorption due to C-H stretching in the vicinity of 2800 to 3100 cm-1 naturally decreases, and
The absorption due to C-F stretching near ~1350 cm-1 increases, and when the ratio of CF4/(CH4+CF4) is 06, the absorption of C-H becomes very small, and the C-F
As mentioned above, the hard carbon layer of the present invention has a high deposition rate, and has a high hardness despite the high deposition rate.Since it uses a compound containing fluorine, it has an etching effect, especially on the chamber wall, and has a high hardness. It is characterized by the fact that it is difficult for powders and films to adhere to it, and the film is made by converting raw material gases consisting of hydrocarbon compounds, fluorine-containing compound gases, and H2, Ar, He, etc. used as necessary into 1O- The film can be formed at a film formation rate of 20 A/sec.

Next, the hard carbon film of the present invention will be explained based on examples.

Example 1 A stainless steel substrate (1) was set on the electrode (cathode) [2) of a plasma CVD apparatus as shown in Fig. 3, the substrate temperature was adjusted to 300°C, and H250SCCH,C
A mixed gas of H432 SCCH and CF4 8 SCCH was flowed, and a voltage of 1600 V was applied to the substrate via the RF choke coil (3) at a reaction chamber pressure of 1 orr to generate a DC discharge with a DC current of 800 mA. At this time, about 5
Apply 0W (100mW/d) RF and DC
and RF discharge was generated. By applying this RF, the problem of charging that occurs when an insulator is deposited can be solved.

The discharge continued for about 60 minutes, and a film with a thickness of about 2.9 μm was obtained. The deposition rate was approximately 8 persons/second.

According to ESCA, the composition of the discipline obtained is approximately H10at.
m%, l''3atll1%, C87atm%, and the Vickers Ra degree was 5200.Furthermore, no film or powder was observed to adhere to the chamber wall other than the electrode portion.

Example 2 and Comparative Example 1 The total flow rate of H250SCCH, Cl14 and CFa was 4
゜5CCH, C) CFJ to the total flow rate of Is and CFa (7) Flow 1 (7) ratio, clogged capacity ratio (C
The capacitance ratio and the fluorine content in the film (ES
CA), the relationship between film deposition rate and Tsukaas hardness was measured.

Ta. These results are also shown in Table 1. Furthermore, the relationship between the capacity ratio and the deposition rate and the relationship between the capacity ratio and the hardness of the grain are shown in FIGS. 1 and 2, respectively.

Note that the pressure, RF power, substrate temperature, OC lightning voltage, etc. were the same as in Example 1.

[Margin below] From the results in Table 1 and Figure 1, the deposition rate increases as the capacity ratio increases, especially when it exceeds 0.1, it increases rapidly, and when it exceeds about 0.6, the deposition rate decreases. , about 085 or more, the film is no longer deposited.

Example 3 and Comparative Example 2 Example 1 and gas volume ratio (CF4 / (CH4
Crystalline silicon, SO3, Cu, N, No.
The adhesion strength of the film formed on the substrate was measured by a tensile test.

As a result of measurement, CF4 / (CH4 + CF4) is 0.35 in the case of substrates made of SO8, Cu, and crystalline silicon.
() to 40 (J/cd, which was good, but 0.4
When the adhesive strength exceeded the above range, the adhesion strength decreased and the film peeled off. In addition, even in the case of a substrate made of No, the adhesion strength is 30 to
It was good at 40 KO/aa, but when it exceeded 0.6, peeling of the film occurred.

Especially in the case of metal substrates such as SO3, Cu, and M, C
，! In the case of a hard carbon film consisting of l:H or a hard carbon film consisting of C, H and F, the hardness is 3006.
In the above film, the internal stress of the film is large and it is easy to peel off, but by including silicon in the above film in a range of 208 tm % or less, the internal stress is relaxed and the film does not peel off. In particular, the effect was remarkable when o, oi to 5 at+n%. The adhesion strength of this film was 30 to 70 Kg/cd.

[Effects of the Invention] When the hard carbon film of the present invention is formed by mixing a gas containing a fluorine-containing compound and performing glow discharge decomposition, the film deposition rate increases as described above, and a highly hard film is formed. Ru. In addition, there is less adhesion of powder and film inside the chamber, and productivity is improved.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the ratio of a specific raw material gas and deposition rate when forming a hard carbon film, and Figure 2 is a graph showing the relationship between the ratio of a specific raw material gas and the deposition rate when forming a hard carbon film. FIG. 3 is an explanatory diagram of an example of the apparatus used for manufacturing the hard carbon film of the present invention. (Main symbols on drawings) (1) Two boards

Claims (1)

[Scope of Claims] 1. A hard carbon film containing 0.1 to 30 atm % of fluorine deposited on a substrate by plasma CVD method. 2. The hard carbon film according to claim 1, which has a surface Vickers hardness of 500 or more. 3. The hard carbon film according to claim 1, wherein the plasma CVD method is an RF plasma CVD method, a DC plasma CVD method, or a plasma CVD method in which both RF and DC are mixed. 4. The hard carbon film according to claim 1, which contains silicon in a range of 20 atm% or less. 5 Ratio of integrated intensity of IR absorption spectrum (▲ There are mathematical formulas, chemical formulas, tables, etc. ▼) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (ω is the wave number, α (C-H) and α (C-F) are 2800~3100cm^-^1 and 1000~1 respectively
2. The hard carbon film according to claim 1, wherein the absorption amount (representing absorption due to each stretching mode existing at 350 cm^-^1) is from 0.001 to 100.