JPH012315A - Method for forming semiconducting carbon thin film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention relates to a method for forming strong thin carbon S by reactive sputtering, and in particular to solid graphite used as a carbon source. For this purpose, the necessary dopants are embedded in the substrate, and this is used as a composite target in accordance with the extremely common sputtering method.
The present invention relates to a method of forming a film.

13.Dedication of the invention "+2 The present invention is based on the sputtering θ which is carried out using a graphite target 314 in a 1"C chamber in an atmosphere containing low pressure water and gas. 011~ in ratio
By using a composite target formed by embedding 10% aluminum.

This eliminates the need for a heart chamber that uses toxic gas and makes it easier to control 11N bamboo.

Conventional technology, plasma CVD (Chemical Vap
our 1) ep.

Carbon fiber with low number of dangling bonds and high resistance, 3μt, etc.
It is known that 1ift view j [ne 6 θ mi.

Therefore, like general semiconductors, this is jntrinq
It is conceivable to use the LC film as a wide gap (Eg=1.5 eV or more) semiconductor by doping it with appropriate impurities.

D1 Problem to be solved by the invention In the case of amorphous silicon manufactured by plasma CVD method, diborane (82H, ) and phosphine (Plj,
) are used, but each gas, including silane (SiH, ), which is the main raw material, is highly toxic.

Hydrogen gas or methane gas is used to form carbon thin films.

Ethane-based gases are often used, and if diborane or phosphine is used for doping, there is a problem in that a new highly toxic gas will be introduced.

Also, when introducing a gas, the ratio of dopant in the gas and F! It is said that the characteristics of the dopant in the film are generally not the same.

Kiichiaki attempts to solve the conventional problems described in ■-.

Means for Solving E0 Spots In main part I11, in order to solve the conventional problems described above, in a method for forming a charcoal thin film by reactive sputtering, O,] is added to graphite in terms of area ratio. In the present invention, a composite target formed by injecting ~10% aluminum is used.In the present invention, a thin film of charcoal is formed in the room by creating an atmosphere containing low-pressure water J3 gas. 9 plates were installed, and a composite graphite target formed by embedding 0.1 to 10% of aluminum per area ratio was installed on the electrode, and high frequency pressure was applied between this and the counter electrode. Then, (a carbon thin film is formed on the plate l-. Since the dopant aluminum is solid, it is easy to handle and control the concentration, and unlike gas, there is no waste in flowing it away).

G. Example DESCRIPTION OF THE DRAWINGS The invention will now be described in detail with reference to the figures.

FIG. 1 shows a sputtering apparatus used in this example. In the figure, 1 is a vacuum chamber, and this vacuum chamber 1 is equipped with an exhaust port 2 and an atmospheric gas inlet 3. In the vacuum chamber 1, a composite graphite target 4 and a counter electrode 5 which also serves as a first substrate holder are installed facing each other. A voltage is applied. A pair of second substrate holding parts 8 are provided opposite to the side wall 1- of the vacuum chamber 1, located on both sides of the opposing H'Xi between the composite graphite target 4 and the counter electrode 5, and a third substrate holding part 8 is provided. The section 9 is located behind the counter electrode 5 and is provided on the side wall of the vacuum chamber 1 . Reference numeral 10 denotes a substrate on which a carbon thin film is to be formed, which is attached to each substrate holder.

As shown in FIG. 2, the composite graphite target 4 is made of graphite with 0.3% aluminum (A
t) 11 is embedded.

When the sputtering apparatus of this embodiment is in operation, as shown in FIG. F2. A region where C, CI 1 species is transported, and a region C where C, C-HM is soft deposited are formed.And.

The second and third substrate holding parts 8.9 are both C1C-
It is arranged in region C where H species are soft deposited.

A specific example in which a fluorine Ely film was formed on the substrate 10F using the soot battering apparatus described in (1)-- will be described below.

- After installing the composite graphite target 4° in the vacuum chamber 1 and the substrate 10 on which the carbon thin film is to be formed, the inside of the vacuum chamber 1 is
．． Reduce the pressure to 33X10'Pa (10'Torr),
) (e/H, +He=50% mixed gas at 40 Pa (
0.3 Torr).

After the indoor pressure (PH,) has stabilized, the high frequency (13°5
6MHz) ffl force to target 4 by 6.8% I/
sputtering was performed for 5 hours. As a result, the characteristics of the carbon thin film formed on the substrate 10 set in each of the holding parts 5, 8.9 are shown in Table 1. For comparison, Table 2 shows the characteristics when using a target made only of graphite.

Table 2 As shown in Tables 1 and 2 above, the resistivity has decreased with almost no change in the bandgap, which indicates that Al
is considered to be incorporated into the carbon 1 film as an acceptor, and this film can be said to be a P-type conductive carbon thin film.

Figure 3 shows the SIMS (S
econdary Ion Mass 5pectro
Scopy (dual ion mass ion spectrometry), from which it is clear that At is incorporated into the film. Furthermore, it is clear from the table "-" that He gas mixing has the effect of increasing the Il formation speed without changing the film properties.

FIG. 4 shows the results of the resistivity ρ and b IC++ of the carbon thin film when the ratio of the area of the embedded aluminum portion to the area of the graphite target 4 was varied.

Fig. 5 shows a composite graphite target 4 in which 0.3% of A1 is embedded in the area cost, and the atmospheric pressure inside the vacuum chamber 1 is P.
H2◆He()le/H,+! 1e=50%) to 1,3
3P a (0, OITorr) ~267 P a
Resistivity ρ and Eg when changed to (2,0 Torr)
This shows the change in n.

The 6th UA is the infrared absorption spectrum of the carbon thin film formed on the substrate 1- set in the hole, where line 1 is the spectrum of the wood example and line 2 is the spectrum of the sample sputtered with only water gas. As shown in Figure 7, He gas and H
, SP of a thin film formed by sputtering of 12 mixtures of gases.
Among the absorptions due to the three-bond bond -H stretching vibration, -〇 H,
The absorption caused by
is decreasing.

However, since the properties hardly changed, it is thought that the amount of excess hydrogen that does not contribute to improving the properties of the semiconducting carbon thin film was reduced.

Figure 7 shows P H, +He between 1.3 Pa and 267 Pa.
Figure 8 shows the deposition rate (r) R) when changing it to Pal, ◆) la = 40 Pa, He Z HJ◆
Figure 9 shows Egn and film formation rate (D R) when He is varied from 3 to 99%, and the substrate temperature is varied from room temperature to 25%.
The film-forming speeds are shown when the temperature is changed to 0°C.

In addition, in Figures 7 and 9, the O mark indicates the film formation rate when lie is not mixed. All conditions not specified are the same. From the results of 1 or more, sputtering with a mixed gas of He gas and H2 gas It is clear that high-quality hemi-n-carbon carbon JM, which has a higher film-forming rate than sputtering using only H2 gas and contains less surplus hydrogen, can be obtained.

The samples shown in FIGS. 3 to 5 are all substrates 10 set in the second J1 (plate holder 8) of the sputtering apparatus shown in FIG. 1M and on which a carbon thin film was formed.

From the data below, the following conclusions can be drawn.

(1) Al embedded in the graphite target is 1
The area ratio is preferably 0.1 to 10%, and the amount of Al is 0.1
% or less, no change in resistivity was observed.

■X, g1. becomes too small, resulting in a wide-gap semiconductor, which is unsuitable.

(2) PH, +lle is 1.33Pa to 665Pa
is desirable, but below 1.33 Pa, both P and Egn are small and it becomes a wide gap semiconductor fB).

Below 1365 Pa, there is almost no doping effect; when the He concentration is less than 3%, no effect of increasing the deposition rate appears; when the He concentration is above 95%, Eg.

This is not desirable as a decrease in Therefore, PH2÷He is 1.33Pa to 665Pa, and He/H2+He =
3 to 95% is desirable.

In addition, for the purpose of increasing ρ and Ego in the 1ntrinsic state, a trace amount (1 to 100 ppm relative to H) is added.
) may be used as a mixed gas containing fluorine Fml oxygen o2, as shown in Table 3.
1n formed using the above mixed gas at
trisic film and embedded composite target (area ratio 0.3
%). In addition,
Other experimental conditions were the same as the previous ones.

In the L2 example, the vll amount gas was set to 1 to 1100 pp because the effect did not appear at 1 pp+*, and at 1100 pp
This is because in the above case, both ρ and Ega become smaller than in the case where they are not mixed.

Note that in carrying out the method of the present invention, various other devices can be used in addition to the sputtering device shown in FIG. Furthermore, implementation conditions that are not particularly limited in the scope of the claims are not limited to the conditions in the embodiments described above.

The method of embedding aluminum into a graphite target is
In addition to the method shown in FIG. 2(a), there are methods shown in FIG. 2(b) and (c). What is important in common to these is the area ratio and uniformity of the embedded portion, and all of these examples can achieve similar effects. The dopant filling method is as follows:
There are methods such as filling with powder and temporarily molding using a vacuum degassing molding method, but any method may be used as long as it does not contain impurity gas during film formation.

H6 Effects of the Invention As described above, in the present invention, in the method of forming a carbon thin film by reactive sputtering, a method is adopted in which a graphite target is embedded with 0.1 to 10% of aluminum in an area ratio of 0.1 to 10%. , has the following effects.

(1) A semiconducting carbon thin film doped with A1 can be formed safely and in a timely manner without using various types of gases such as a combination of special gases such as (CH, ) and A1.

(2) By changing the area ratio of aluminum in the composite graphite target, carbon? - The dopant concentration in the film can be easily controlled.

(3) Unlike the gas doping method, there is no waste of gas flowing, so there is a doping effect with a small amount.

(4) Since aluminum as a dopant can be used in powder or granular form, it is easy to handle.

(5) When the sputtering gas is a mixed gas of H7 and Hr=, it is possible to form a benign film with a small amount of hydrogen that does not interfere with the characteristic direction 1-.

(6) Since the mixed gas mentioned above increases the film formation rate, a constant film thickness can be obtained in a shorter time than when using only H2 gas.

(7) According to (1), it is possible to grow the substrate at temperatures up to 250°C.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention.
2(a), (
b) and (c) are composite graphite target ilZ
Figure 3 is a diagram showing the concentration profile by SIMS, Figure 4 is 'J4. Resistivity ρ due to aluminum surface 1d ratio of f-matching graphite target
Figure 5 is a diagram showing the dependence of resistivity ρ on mixed gas; Figure 614 is a diagram showing the infrared absorption spectrum of a carbon thin film formed on a partially set substrate; Figure 7 shows pH, +He: 1, :3 Pa-26
Figure 8 is a chart showing the film formation rate (IR) when changing it up to 7P a. EF! ++ and a chart showing the 1:9 deposition rate (Dl), and FIG. 9 is a chart showing the film deposition rate when the substrate temperature was changed from room temperature to 250°C. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 4... Composite graphite target, 5... Counter electrode, 6... High frequency power supply, 10...
Substrate, 11...aluminum. Fig. 1 Zupa, da disaster 1--Ichine Kokasumi 4--11 Graphite tardito 5--Ichisuke-sukejiken wo 6--Ji 1fl's 3 geese 10--53 counters 11-11 view l Hyaluminum ≦ Um Figure 3 According to SIMSIC = fi degree pro 7 Isle snow dust vr interval (min,) According to Figure 4 aE M9. Ego atlb surface ratio ('1.) Go to Figure 7' System temperature (D, R,) Gas pressure]K Dust resistance PHz
+He (Torr) CHe/Hz He = 50') Absorption # number (cm') ○ 9 (Ω・cm) Figure 8 fv-1M 宸Ego /l n'suL 藏洛KHe/
)-1z Now He ('/6) 9th
To the figure, the 4-plate temperature of the film temperature is 0C.

Claims (5)

[Claims] (1) In a sputtering method in which a carbon thin film is formed on a substrate using a graphite target in a vacuum chamber in an atmosphere containing low-pressure hydrogen gas, the graphite target is formed by embedding aluminum in an area ratio of 0.1 to 10%. A method for forming a semiconducting carbon thin film, characterized in that: (2) The method for forming a semiconducting carbon thin film according to claim (1), wherein the vacuum chamber pressure is set to 1.33 to 665 Pa. (3) The atmosphere in the vacuum chamber is a mixed gas of hydrogen gas and helium gas, and the ratio is He/H_2+He=3.
Claim No. 1 (1) characterized in that the ratio is 95%.
) The method for forming a semiconducting carbon thin film according to item 1. (4) The method for forming a semiconducting carbon thin film according to claim (1), wherein the temperature of the substrate is set in a range from room temperature to 250°C. (5) The method for forming a semiconducting carbon thin film according to claim (1), wherein the atmosphere in the vacuum chamber is a mixed gas atmosphere of fluorine gas, oxygen gas, and hydrogen gas.