JPH03199376A - Hard carbon film forming method - Google Patents

Abstract

PURPOSE:To form a hard carbon film having a high degree of adhesion to a substrate by forming middle layers including a soft carbon film on the substrate and then forming a diamondlike carbon film. CONSTITUTION:A soft polymeric carbon film (middle layer) 15 is formed on a substrate 7. A polymeric carbon film (middle layer) 16 having higher hardness than the film 15 is formed on the film 15. A diamondlike carbon(DLC) film 20 is then formed on the film 16. About 10<10>dyn/cm<2> compressive stress remains usually in the DLC film 20 and compressive stress nearly equal to that in the film 20 has been produced in the upper layer part of the lower polymeric carbon film 16. The film 16 contains the same carbon as the DLC film 20 contains.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hard carbon film forming method for forming a hard carbon film on a substrate.

[Conventional technology]

In general, l) L C (Diamond Like C
arbon) 1m is superior to diamond l in terms of hardness, insulation, thermal conductivity, light transmittance, and chemical stability.
It has been attracting attention recently because it has excellent properties similar to that of ゛.

This DLCM! For manufacturing, ion beam method, sputtering method, ion blating method, and plasma CV
Various methods such as D method are used.

Recently, as a type of plasma CVD method, ECR (Electron Cy
Clotron Re5onance) Plasma CVD
A method has been developed and is already in use.

In the F, CR plasma CVI) method, a high-density plasma is generated under low gas pressure by exciting electron cyclotron resonance. This plasma flow is extracted by a divergent magnetic field from an ECR ion source, and is irradiated onto a sample such as a substrate to form a film.

[Problem to be solved by the invention]

611 DI on the substrate using the manufacturing method described above.

When a C film is formed, the DLC film has a 10” dyne/
A high compressive stress on the order of "cra" remains.For this reason,
The adhesion between the DLC film and the substrate, especially the metal substrate, is poor.
Problems such as peeling and cracking occur during the production of the LC film.

Therefore, it is conceivable to provide an intermediate layer having good adhesion to the substrate, for example, an intermediate layer made of a silicon component, between the substrate and the DLC film. With such a method, it is possible to increase the adhesion between the substrate and the intermediate layer. However,
The interatomic distance between silicon atoms is larger than the interatomic distance between carbon atoms contained in the DI and C films. For this reason, the middle class and D
There is a limit to sufficiently increasing the adhesion between the film and the LC film.

An object of the present invention is to provide a method for forming a hard carbon film that has high adhesion to a substrate.

(Means for Solving the Problem) The hard carbon film forming method according to the present invention is a method for forming a hard carbon film on a substrate (and includes the following steps).

◎ Forming an intermediate layer containing a soft carbon film on the substrate.

◎ Forming a diamond-like carbon film on the intermediate layer.

[Effect]

In the hard carbon film forming method according to the present invention, first, an intermediate layer containing soft carbon l1ff is formed on a substrate.

A diamond-like carbon film is then formed on this intermediate layer. This intermediate layer is soft and has good adhesion to the substrate. Furthermore, since this intermediate layer contains carbon atoms contained in the diamond-like carbon film, it has good adhesion to the diamond-like carbon film. Therefore, the intermediate layer acts as a buffer material, and a hard carbon film is formed that has high adhesion to the substrate and is free from peeling, cracking, and the like.

[Fruitful: Example]

First, an ECR plasma C to which an embodiment of the present invention is applied
The VD device will be explained. Figure 2 shows ECR plasma C
It is a cross-sectional horizontal view of the VD device.

In the figure, the plasma chamber l is the microwave (
It is configured to be a cavity resonator for a frequency of 2.45 GI + □), and has a diameter of 20 cm and a height of 20 cm, for example.
It is a cylindrical chamber of ca+. A cooling jacket 10 is provided around the plasma chamber I to prevent the rise in temperature -L of the wall surface due to plasma formation. Cooling water can be circulated through this cooling jacket 10. A waveguide 3 having a rectangular cross section for introducing microwaves is connected to the plasma chamber 1 via a microwave introduction window 2 made of quartz or the like. A gas introduction hole 13 is formed in the upper part of the plasma chamber l. Further, around the plasma chamber 1, electromagnetic coils 4a and 4b are arranged as a magnetic circuit for generating plasma. Electromagnetic coil 4a
, 4b is determined such that the conditions for electron cyclotron resonance due to the M/F U waves are established inside the plasma chamber I. These electromagnetic coils 4a and 4b form a completely destroyed magnetic field that diverges downward.

A sample chamber 5 is provided below the plasma chamber 1 .

In the lower part of the sample chamber 5, a substrate 7 is held by a substrate holder 8, and is irradiated with a plasma flow M extracted from the plasma chamber 1. The cutting board holder 8 is attached to a support shaft 9. Further, a high frequency power source (eg, frequency 13.56 MH2) 11 is connected to the substrate holder 8G via a support shaft 9, so that a predetermined high frequency voltage is applied to the substrate 7. Further, the high frequency power source 11 is configured to be able to change the power supply voltage applied.

Note that the substrate holder 8 is equipped with a jacket (not shown) through which cooling water circulates. Further, a shutter 12 that can be opened and closed is provided above the substrate holder 8. By adjusting the opening degree of this shunter 12, the irradiation of the plasma flow M to the base Fi7 can be adjusted. , an exhaust hole 5a is formed in the lower part of the sample chamber 5,
This exhaust hole 5a is connected to an exhaust system (not shown).

Next, a method for forming a hard carbon film will be explained while explaining the operation of this apparatus.

First, the substrate 7 on which a film is to be formed is held by the substrate holder 8. Next, the plasma chamber 1 and the sample chamber 5 are brought into a vacuum state by an exhaust system (not shown), and the internal gas F[ is reduced to 5×10−
'Reduce Torr or less. Then, a hydrocarbon gas, for example C1 gas, is introduced into the plasma chamber 1 through the gas introduction hole 13.

Next, the electromagnetic coil 4a provided around the plasma chamber 1
, 4b so that the magnetic flux density in the plasma chamber 1 becomes 875 Gauss. Further, at this time, no high frequency voltage is applied to the substrate 7. From this state, microwaves with a frequency of 2.45 cut are introduced into the plasma chamber 1 via the waveguide 3 to generate plasma in the plasma chamber 1.

Under these conditions, in the plasma chamber 1, 87
The frequency of the electrons rotating due to the 5 Gauss Lufi field and the microwave frequency of 2.45Glh match, and the electron zaiku ``Kawa and Me 1!8'' do not occur. The accelerated electrons efficiently collect energy and accelerate.The accelerated electrons collide with gas molecules and ionize and destroy the gas molecules, generating high-density plasma at other gas pressures.Plasma chamber The plasma generated in the magnetic coil 1 is drawn out along the lines of magnetic force of the diverging magnetic field formed by the electromagnetic coils 4a and 4b.

Next, the shutter 12 is opened. Then, the Blaz°7 flow drawn out from the plasma chamber 1) is irradiated onto the Jii plate 7, and a soft polymeric carbon crotch (intermediate N) 15 is formed on the substrate 7, as shown in FIG. 1A. . The compressive stress within this soft polycarbonate film 15 is approximately zero. Therefore, the soft polymeric carbon film 15 is attached to the substrate 7. L
Adheres well to.

When the soft polymeric carbon film 15 reaches the required thickness, a frequency of 13.56 is applied to the substrate 7 from the high frequency power source 11.
A high frequency voltage of M1+□ is applied, and the applied voltage is gradually increased. Then, in the same manner as above (, CL gas plasma is generated in the plasma chamber l. Also, at this time,
The board 7 is connected to a frequency 13. 56M1l
Since the high frequency voltage Z is applied, positive and negative potentials are periodically applied. As a result, a negative self-bias (-100V or less) is generated in the substrate 7. Due to this negative self-bias, positive ions in the plasma are drawn toward the substrate 7 side, and as shown in FIG. A polymeric carbon film 16 (intermediate layer) is formed. This polymeric carbon film 16 has hardness and compressive stress comparable to that of the soft polymeric carbon film 15 in its lower layer region, and the hardness and compressive stress increase toward the upper layer.

Next, the power of the high-frequency wave Y applied to the substrate 7 is increased, and high-density plasma is generated in the plasma chamber 1 under the same ECR plasma conditions as described above.

The emitted plasma flow M is electrically lit 21 il 4a,
It is pulled out into the sample chamber 5 by the divergent magnetic field of 4b and irradiated onto the substrate 7. At this time, since a negative self-bias (-100 V or less) is generated in the substrate 7, positive ions in the plasma are drawn toward the substrate 7, and as shown in FIG. 1C, the polymeric carbon film 16 DI, C film 2 on top
0 is formed.

This DLC film 20 usually has 1010 d yn
A compressive stress on the order of e/C1"rl" remains. on the other hand,
D.I.

A compressive stress comparable to this compressive stress is generated in the upper layer portion of the polymeric carbon film 16 which is the lower layer of the C film 20.

Further, the polymeric carbon film 16 contains carbon contained in the DLC film.

Therefore, the DLC film 20 is composed of polymeric carbon +19
Adheres well to 16.

In this way, it is possible to form an LC film on the substrate 71 through a series of treatments (1) which has good adhesion to the substrate 7 and does not cause peeling or cracking.

Next, the results of comparing the physical properties of the DL,C film and the soft polymeric carbon film will be shown.

Experiment ItoThe term "polymer carbon film" mentioned below refers to the first
This refers to the soft polymer carbon film 15 in Figure C.

(1) Experimental method The substrate used in the experiment was a 6-inch S resistor. Further, the film forming conditions were set so that the film thickness distribution was within ±5%. Under these conditions, the film deposition rate was 75 people/mi
It was n.

(2) Hardness For hardness measurement, use a microhardness meter II M V2O manufactured by Uozu ■.
00 was used. The indenter used was a Knoop indenter.

A DLC film with a thickness of 1 μm was formed on a Si wafer substrate 1, and the hardness was measured. As a result, the hardness of the DLC film was 2150 kg/mm'', and the hardness of the polymeric carbon film was about 100 kg/m.

(3) Refractive index For measurement of refractive index, Ar-II e laser (63
Shima Ritsu's automatic polarization analyzer AI'i using 28 people)
P-100 was used. In addition, the absolute membrane of the sample was measured in advance using a stylus-type membrane meter, and then the measurement was carried out using the polarization analyzer described in +iii. As a result, D
The refractive index of the LC film is 2.09, and the refractive index of polymeric carbon 1 is 1.09. It was 6.

(4) JIC resistance rate 1) 1. The resistivity of the CJ model is more than IQIZΩ・c1n, and the resistivity of the polymeric carbon film is about 3X
It was 101zΩ·cm.

(5) Chemical stability The measurement was performed using the same method as the force method used to measure the etching rate of B II I” (buffered hydrofluoric acid), which is a method for evaluating the acid resistance of SiNx films. l”
A liquid mixture of No., No., and rr at a ratio of 1:6 was used, and the liquid temperature was set at 30°C. As a result, DLCH'A [
1) The IF etching rate was about 10 people/h.

Further, although no measurements were made for polymeric carbon films, the B It F etching rate for Si wafers was approximately 110 etching/h.

(6) Raman hand I/Ruraman spectroscopy is one of the important means of evaluating the internal structure of carbon films, since it is possible to evaluate even amorphous materials. The laser used was an argon ion laser.
A 4.5 nm oscillation line was used. In the case of D L, C film,
The obtained Raman spectrum had a Raman hand around 1550 cm-' and a shoulder band around 1350 crrr'. on the other hand,
Regarding the polymeric carbon crotch, significant fluorescence was emitted during Raman spectroscopy.

(7) Hydrogen concentration in the film The hardness of the film is thought to depend on the hydrogen content in the film. Therefore, we used heavy ions to knock out the carbon and hydrogen in the membrane.
ERl) A (+41asLic
Recoil [1action analysis
The hydrogen concentration in one simulation was measured using the is) method.The results were as follows: 1. , the II/C original P number ratio of the C film is 0.17
It was in the range of ~0.34. On the other hand, polymeric car I
! The H/C atomic ratio of N-Kin was in the range of 0.53 to 0.80. This value is +1 °ζ compared to the L C film about 2 to 3
It's twice as expensive.

(8) Emission spectrum The emission spectrum from methane plasma during film formation was observed. As a result, there was almost no change in the relative intensity ratio of the 11 emission spectra between the formation of the DLC film and the formation of the polymeric carbon film, but the density of the 11 radicals observed during the formation of the polymeric carbon film was , DLC
It was found that the membrane was about 25 times more sensitive than when it was produced. Therefore, it is considered that when the density of the [■] radicals is high, the [1] radicals are taken into the film during film formation, and as a result, a soft polymeric carbon film is produced.

A summary of the above results is shown in the table below.

[Other Examples]

(a) In the third embodiment, by changing the high frequency voltage (bias voltage) applied to the substrate 7,
polymeric carbon crotch 15.16 as an intermediate layer, and D
1. /R was made to form a C film, but
Application of the present invention is not limited to this.

For example, it is possible to form a polymeric carbon film and a DLC film in the same way by setting the microwave power and pressure under appropriate conditions.

(1)) Formation method G1 of polymeric carbon film and DLC film is not limited to ECR plasma CVD method.

For example, plasma CVD method or sputtering method.

Alternatively, ζ may be formed using the ion bee method.

(C) In the above examples, polymeric carbon film and film 1. CIQ (7) Formation CR plasma C
Although VD device wt was used, polymeric carbon film and l
) 1. c III may be formed in separate devices.

For example, the formation of a polymeric carbon film is performed by vapor deposition, followed by LiCR plasma CVD deposition.
1. It is also possible to form a C film.

(,')! 'l: I aL! Loss of consciousness! ! In the example, the intermediate layer is 1 layer of polymeric carbon and 1 layer! 'i, 16(
2) The figure consists of 211 m, but the middle layer is
(() may be a single layer and may be 7-7, or may be composed of multiple layers of 3-layer plates 1-2) ((also 4L).

[Effect of 191] In the hard carbon film forming method according to the present invention, diamond [
The carbon crotch is formed on the substrate I through an intermediate layer containing soft carbon 1, so it forms a hard carbon film that has good adhesion to the substrate and does not peel off when cranks, etc. be able to.

[Brief explanation of drawings]

1A to tC are diagrams for explaining a hard carbon film forming force method according to an embodiment of the present invention, and FIG. 2 is an IE CI? to which an embodiment of the present invention is applied. Plas°Z CV
FIG. 3 is a schematic cross-sectional configuration diagram of the D device. 'l...Substrate, 15...Soft polymer-like carbon film, 16...Polymer-like carbon film, 20...I)
L C] model.

Claims (1)

[Claims] (1) A hard carbon film forming method for forming a hard carbon film on a substrate, which comprises forming an intermediate layer including a soft carbon film on the substrate, and forming a diamond-like carbon film on the intermediate layer. A hard carbon film forming method comprising: