JPS6367721A - Manufacture of amorphous carbon semiconductor film - Google Patents

Abstract

PURPOSE:To manufacture an amorphous carbon semiconductor film which is easily controlled in the quality of the film without heating nor damaging on a substrate to be deposited and has a resistance value to be easily semiconductor by using as sputtering gas mixture gas of hydrogen gas and nitrogen gas, and specifying the mixture ratio and the whole pressure of the sputtering gas. CONSTITUTION:A graphite target is mounted on a carbon target electrode 5, a substrate 8a to be deposited is disposed near the upper wall of a vacuum chamber 1, a substrate 8b to be deposited is disposed near the sidewall of the chamber 1, and a substrate 8c to be deposited is disposed on an opposed electrode 4. Then, a vacuum vessel 1 is evacuated, for example, to 1.33X10<-5> Pa (10<-7> Torr), and 1-50 Vol.% of N2/H2+N2 of mixture gas is introduced. Then, after the total pressure (PH2+N2) in the chamber 1 is set to 1.3-665 Pa, power of high frequency (13.56 MHZ) is set, for example, to be 6.8 W/cm<2>, and sputtered for 5 hours. As a result, electric resistivities as characteristic of the carbon thin film formed on the substrates 8a, 8b, 8c at setting positions are lowered as compared with the case that only hydrogen gas is used as sputtering gas. Absorption of SP<3> bond of the carbon thin film due to C-H elongation and shrinkage vibrations is reduced by the spectrum of line (b), but SP<2> (absorption at 3025cm<-1>) bond is not almost observed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to a method for manufacturing an amorphous carbon semiconductor film.

B0 Summary of the invention This invention is a method for performing reactive sputtering using graphite as a target electrode, in which the sputtering gas is a mixture of hydrogen gas and nitrogen gas,
The mixing ratio (8ri) is 1.0 to 50 vot.

H2+N2 H, total pressure of sputtering gas (PH2+N2) 1.3 to 6
65 Pa, it is possible to produce an amorphous carbon semiconductor film without heating or damaging the deposited substrate, easily controlling the film quality, and having a resistance value that makes it easy to convert into a conductor. be.

C1 Prior Art Conventionally, methods for manufacturing diamond-like carbon thin films or amorphous carbon thin films include ion beam methods, plasma CVD methods, and the like.

Furthermore, in recent years, as a new method for producing carbon thin films, a method has been used in which graphite is sputtered with hydrogen gas or a mixed gas of hydrogen and other gases.

D1 Problems to be Solved by the Invention However, such conventional methods have the following problems.

(b) In the ion beam method, since the substrate is irradiated with an ion beam, structural defects are likely to occur at the interface, and it is difficult to form a film on areas that are easily attacked by the ion beam, such as organic materials and semiconductors. Ta.

(b) In the plasma CVD method, the substrate is easily exposed to plasma and is easily damaged, and in order to improve the film quality, the substrate temperature must be raised to 200°C or higher, which limits its application. It is easy to receive.

6) In the method of sputtering graphite,
A very high quality carbon thin film can be formed, but when considered as a semiconducting carbon thin film as an intrinsic semiconductor film, depending on the application,
Too much resistance.

The present invention has been made to address these conventional problems, and does not cause heating or damage to the deposition substrate.
The object of the present invention is to obtain an amorphous carbon semiconductor film whose film quality can be easily controlled and which has a resistance value that is easy to convert into a semiconductor.

Means for Solving Problem E6 The present invention introduces a sputtering gas consisting of a mixture of hydrogen gas and Ω element gas into the vacuum chamber of a sputtering apparatus using graphite as a target electrode, and then mixes the hydrogen gas and nitrogen gas. Mixing ratio (N8□2+N2) from 1 to 50 vot,%
The structure is such that the reactive sputtering is performed under the condition that the total pressure (PH2+N2) of the mixed gas is 1.3 to 665 Pa.

By sputtering, the 18-active hydrogen gas combines with C of graphite, which is a ditarget, to form C-Hfl[, and this C-Hg adheres to the deposition substrate to form a film. Further, since the nitrogen gas is mixed with the sputtering gas, it has the effect of reducing the localized level at the band edge and reducing the resistance of the formed amorphous carbon film.

G. Examples Hereinafter, a method for manufacturing an amorphous carbon semiconductor film according to the present invention will be explained in detail based on examples shown in the drawings.

First, a sputtering apparatus used in the present invention will be explained based on FIG.

In the figure, numeral 1 is a vacuum chamber, 2 is a sputtering source gas introduction pipe, and 3 is an exhaust pipe, which are connected to a vacuum pump (not shown). Reference numeral 4 indicates an electron extraction counter electrode at ground potential, and reference numeral 5 indicates a target electrode, which are connected to a high frequency (R, F,) power source 7 via a matching box 6. 8a, 8
Reference numeral b denotes a deposition substrate placed within the vacuum chamber 1 and outside the region to which the plasma excitation source is transported, and 8c denotes a deposition substrate placed on the counter electrode 4.

In addition, in the same figure, part A, part B, and part 0 indicate conceptually divided areas within X vacant room 1, and part A indicates the range surrounded by song ia, and both This is a region in a plasma state that is generated between the electrodes and around it, and in this region, C, CM, CH2, CM generated from the target electrode 5
Particles such as 5, CHII, C2H1l, and C2H6 are present.

Part B indicates the range excluding part A, which is surrounded by the curve,
This is the region in which the particles present in the plasma are transported, and the speed thereof is determined by the pressure of the atmospheric gas and the voltage between the electrodes.

Section C indicates an area within the vacuum chamber 1 excluding sections A and B, and is an area where the above-mentioned particles are transported and softly deposited onto the deposition substrate 8 placed on the inner wall of the vacuum chamber 1.

In this embodiment, using the sputtering apparatus having the above configuration, sputtering is performed under the following conditions.

That is, the graphite target is connected to the carbon target electrode 5.
The deposition substrate 8a was placed near the upper wall 9 of the vacuum chamber 1, the deposition substrate 8b was placed near the side wall of the vacuum chamber 1, and the deposition substrate 8c was placed near the counter electrode 4.

Then, the pressure inside the vacuum chamber 1 is 1.33X10-'Pa (IQ
-7Torr) and N2/H2+N2 to 1o
vot,% mixed gas at 67 P& (0,5 Tart
).

Next, after the gas pressure (PH2+N2) in the vacuum chamber 1 stabilizes, high frequency (13,56MH2) 1! power 6.8
Sputtering was performed for 5 hours at a setting of W/cm.

As a result, the deposition substrate 8a at each setting position.

The characteristics of the carbon thin films formed on 8b and 8c are shown in the table below. For comparison, the characteristics when nitrogen gas (N2) is not mixed are also shown in the right column of the table.

As shown in the table above, when nitrogen gas is mixed with hydrogen gas at a ratio of 10 VO 4%, the electrical resistivity is lower than when only hydrogen gas is used as the sputtering gas. The results were obtained.

FIG. 2 shows the infrared absorption spectrum (line A) of the carbon thin film formed on the deposition substrate 8a placed on the upper wall of the vacuum chamber 1;
This is a graph showing the infrared absorption spectrum (height) of a sample sputtered with only hydrogen gas.

As shown in the same figure, the absorption due to the C-H stretching vibration of the SP5 bond in the carbon thin film fabricated by sputtering in the presence of a mixed gas of nitrogen gas and hydrogen gas is reduced from the line -〇 spectrum. However, SF3 (absorption at 3025 cm-') bond is rarely seen.

Also, based on nitrogen (N-H (3350-3300crn
-' ) and C-N (2820~, 2760crn-1)
No signal was seen.

In addition, Figure 3 shows the absorption coefficient (α) measured to determine the optical band gap (Ego) with respect to the photon energy (αhν) versus hν (hniblank constant, si:
It is plotted in the form of (frequency of light).

Similarly to FIG. 2, line A shows the characteristics of the carbon thin film according to this example, and line a shows the characteristics of the carbon thin film based only on hydrogen gas.

According to the figure, the characteristic of line A is that absorption at photon energies below Ego is reduced compared to the characteristic of the line mouth. This means that by mixing nitrogen gas with the sputtering gas (sputtering source gas), the localized level at the band edge is reduced, and this is one of the factors that reduce the resistance.
It is thought that there is one.

Furthermore, FIG. 4 shows PH2+N2 ("3's.+N2
Let's say 1 vo4 chi. ) and the optical bandgap Ego measured by changing the value from 1.3 Pa to 267 Pm.
Figure 5 is a graph showing the relationship between PH2+N2
Assuming 67Pa, N5/1!2+N2 is 1 voL%~
It shows the relationship between ρ and Ego when it is changed to 50 vo4%.

As described above, the carbon thin film produced by this method has Ego
While maintaining a wide gap of = 1.8 aV or more, it has a relatively low resistance value of ρ = lO ~ 10 Ω・m, and is an amorphous carbon intrinsic (1 ntrinsic) semiconductor film containing almost no SP2 bond. This becomes clear.

Note that if PH2, N2 is below 1.3 Pa, Ego is too low, and if it exceeds 665 Pa (C5, OTart), defects such as voids tend to occur in the lower part of the resistance. is 1.3
Pa~665Pa.

The concentration of nitrogen gas relative to hydrogen gas is preferably 1 to 50 vol.

Although the embodiments have been described above, in the method for manufacturing an amorphous carbon semiconductor film according to the present invention, the structure of the sputtering device, the sputtering power for 1 hour, etc. are not limited to the method of the above embodiments, and the The setting position is not limited to the position set in the above embodiment.

Effects of the H0 Invention As is clear from the above explanation, 1. In the method for manufacturing an amorphous carbon semiconductor film according to the present invention, by using a mixed gas of hydrogen gas and nitrogen gas under predetermined conditions, (f) Maintain a wide gap of Eg = t, s eV or more.

(b) There are few localized levels near the band edge.

(c) ρ = 107 to 1010 Ω - a resistance value that is easy to convert into an extrinsic semiconductor.

This has the effect of making it possible to manufacture an intrinsic amorphous carbon semiconductor film having the above (a), (b), and (c).

Further, it has the effect of making it possible to produce a carbon film that contains almost no CC sp bonds and has a lower resistance value than conventional carbon films.

Furthermore, by locating the deposition substrate at a position outside the plasma state or transport region, surface damage caused by the ion beam can be prevented, and damage caused by exposure to plasma, deterioration of film quality, and temperature increase of the deposition substrate can be prevented. It has the effect of preventing

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a sputtering apparatus used in an example of the method for manufacturing an amorphous carbon semiconductor film according to the present invention, FIG. 2 is a graph showing an infrared absorption spectrum, and FIG. Figure 4 is a graph showing the relationship between αhν)0°5 and hν.
A graph showing the gas pressure dependence of go, Figure 5, shows the resistivity ρ
It is a graph showing the nitrogen concentration dependence of the optical band gap Ego. 1... True nitrogen chamber, 5... Target electrode. Fig. 1. 0 ← g 珂; 2-use Nisba/ri 117 ・G 珂 (2nd
Figure passed away)-43 (Gsuhe Kutkul 1 Show 1ri/7-733
CK) 3100 2900
2700 25(X) Yu Sui (am
) Fig. 3 (αhV) o, s and hv h0 function i nail 1 graph phyton energy (eV) Fig. 4 PH2+N2 (Torr)

Claims (1)

[Claims] A sputtering gas consisting of a mixture of hydrogen gas and nitrogen gas is introduced into the vacuum chamber of a sputtering device using graphite as a target electrode, and the mixture ratio of hydrogen gas and nitrogen gas (N^2/H_2+N_2 ) from 1 to 50 vol. %, and the total pressure of the mixed gas (P_H__2_+
_N___2) is 1.3 to 665 Pa, and reactive sputtering is performed.