JPS62115710A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve characteristics of a solar battery photodiode and the like, by radiating 185nm light without mixing mercury vapor in reaction gas, when alloy is minutely crystallized by photo-excitation CVD method, so that a doping layer of extremely low resistance can be obtained with its band gap being different from that of a Si-single thin film. CONSTITUTION:In a semiconductor device whose main constituent is a non-single crystalline silicon group semiconductor containing hydrogen, at least one layer of p-type or/and n-type semiconductor layers is an alloy necessarily containing Si and H and containing at least one kind of C, N, and O, being provided with dopant such as P or B. Besides, the semiconductor layer is formed by a chemical gaseous phase growth method of light radiation so that conductivity of the semiconductor layer becomes 10<-3>OMEGA.cm<-1> or more. The semiconductor layer is formed by using Si2H6 as a Si source and using ultraviolet rays at least containing light whose peak wavelength is about 185nm as a light source. Hence, non-single crystalline alloy with a large band gap can be formed without use of laser light-radiation annealing.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a semiconductor device having a thin film semiconductor.

In particular, the present invention relates to a method for forming a semiconductor layer suitable for solar cells, photodiodes, or FET devices.

[Background of the invention]

Conventionally, in amorphous silicon-based photovoltaic devices, it has been common to use amorphous S i C:H for the two layers as disclosed in Japanese Patent Application Laid-open No. 58-171868. However, compared to amorphous SiC:H, amorphous SiC:H has a wider bandgap and better light transmittance, but has lower conductivity and 10Ω-
1.■-E to 10-δΩ-1.Cm-1. This low conductivity 1 leads to an increase in series resistance in photovoltaic devices, which limits the improvement of photovoltaic characteristics.

On the other hand, 1985 Spring Applied Physics Society Preliminary Lecture 31p-T-
As shown in Figure 5, amorphous SiC:H can be crystallized by laser irradiation annealing and its conductivity can be reduced to 10-8Ω-.
It is known that it can do more than "CIl-".

It has been proposed to apply this to photovoltaic devices.

However, in this method, d parts other than amorphous SiC:H, such as amorphous 5iC, are removed by laser beam irradiation.
The transparent electrode under the xH layer was also subjected to heat treatment, and the problem of diffusion of the material was unavoidable.

[Purpose of the invention]

An object of the present invention is to provide a method for forming a non-single crystal alloy having a large band gap and a conductivity of 10-8 Ω-1·Qll-'' or more without using laser light irradiation annealing. be.

[Summary of the invention]

As mentioned above, in alloys such as S i C: H,
It was known that annealing with laser light irradiation causes microcrystalization and a rapid decrease in resistance value. However, a method for microcrystallization during film formation using a plasma CVD method or the like has not been known. Since silicon hydride is more easily microcrystallized by photo-excited CVD than by plasma CVD, the inventor investigated conditions for microcrystallizing an alloy using photo-excited CVD. As a result, it was revealed that the conditions under which a doped layer with much lower resistance than before can be formed by irradiating with 185 nm light without mixing mercury vapor into the reaction gas were clarified.

As the reaction gas, the following can be used. Si sources include 5izHe, S
Silane gas such as iHa, 5iaHa, S i H
4,5iHz Gas containing halogen such as CQ2, CHa
An alkylsilane gas such as SiHa* (CI(s)zsiHz) can be used. As Cg, Cz H
Hydrocarbon gas such as x, Cz H4 or ((, H3)zs
Alkylsilane gas such as iHz can be used. Also.

For the preparation of SiN:H alloy, N[as NHa+N2
etc., and for producing SiO:H alloy, 0
Oz, NzO, etc. may be used as the source. Of course, in addition to the essential components of C, N, and O as mentioned above, F
, Ge, etc. may be included.

As dopants, B2H8 diluted with hydrogen was used to form a p-type film, and PH3 diluted with hydrogen was used to form an n-type film. Of course, gas diluted with He, Nx, Ar, etc. may be used, or BFa + PBra etc. may be used.

The gas used in the reaction contains H at a ratio of 0.5 or more to the Si source gas component in the mixed gas during the reaction for microcrystallization.
Must include z. If this ratio cannot be achieved only with H2 contained in the source gas as a diluent gas,
Separately introduce Hz gas.

Also, 1 unit gold 5ll-XXX: H (X = C + O
+N) is suitably 0.05 to 0.5 since it becomes difficult to lower the resistance if the ratio of X becomes too high. Furthermore, it is desirable that the deposition rate be slow;
．． It is preferable to perform the deposition at a rate of 0.05 to 0.5 people/S.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 This will be explained using FIG. 5bzO on glass substrate 1
A transparent electrode 2 made of Snow containing a was formed, and a semiconductor thin film made of a silicon-based alloy was formed thereon. First, the substrate was heated to 200°C.

100% 5izHa: 10%Cz'HzCHz dilution)
: 1% BzHa (Hz dilution) = 20:30:8 ratio of the reaction gas was introduced into the reaction chamber, and while evacuated to maintain the temperature at 2 Torr, a low-pressure mercury lamp was used to evacuate the reaction gas to at least 185 nm.
The window material was selected so that the light could reach the reaction chamber, and the light was irradiated. This allows p-type SiC:HM! Formed J3 with 100 members. When a thicker film was formed and the film quality was evaluated, the band gap was 2.1 eV and the conductivity was lXl0-"
It was Ω-1-■-1.

Next, 100% 5izH6 and 1 ppmB zHe (H
i-type amorphous Si doped with a trace amount of B by A dilution)
: 5000 people formed H layer 4. More 100% 5iz
n by He and 500 ppm P Ha (H2 dilution)
Type microcrystalline Si:H layer 4 was formed by 300 people. This i
Both the type layer and the n-type layer were formed by plasma CVD.

Next, as the back electrode 6, AQ was deposited in a pattern of 1 μm using a mask deposition method. Finally, etching was performed using the back electrode 6 as a mask to obtain the shape shown in FIG. Plasma etching was performed using DF40 oz (4-8%).

When the photoelectric conversion characteristics of this device were measured under sunlight (100 mW/a+F), a conversion efficiency of 10% was obtained.

Example 2 This will be explained using FIG.

P-type amorphous Si is formed on the SUS substrate 11 using 1000pp hazy BzHs (Hz dilution) and 100% 5iHa.
:H layer 12 was formed by 300 people, and then the i-type amorphous Si doped with a trace amount of B was formed.
5000 people were formed using 2H1 and 100% SiH4.

All of these were formed by plasma CVD. next,
100% 5izPIe, 500ppmP Ha (
H2 dilution), high purity 02 mixed gas is introduced into the reaction chamber, and 0
．． While maintaining the temperature at 5 Torr, light was irradiated with a low-pressure mercury lamp by selecting a window material so that light of at least 185 nm could reach the inside of the reaction chamber.

This results in a bandgap of 1.9eV and a conductivity of 1.0Ω.
-"Cl1-1 n-type Si○:H layer 14 was formed by 150 people.Finally, ITo(Ir+zOx+SnO
The photoelectric conversion efficiency was 8.5% in 6 devices in which 700 transparent electrodes 15 were formed using a mask made by the electron beam evaporation method.

In the above embodiments, all layers other than the alloy layer containing C and O were formed by plasma CVD, but they can also be formed by photo-CVD. In addition, as a light source for forming the above-mentioned alloy layer, not only a low-pressure mercury lamp but also a deuterium lamp, a Xe lamp, or a laser beam having a wavelength of 200 nm or less can be used. can. Further, the device structure is not limited to the above, for example, transparent electrode/pin(I)/pi
The present invention is also applicable to tandem solar cells such as n(■)/metal substrates. moreover.

Photodiodes and TFTs (Thin
Needless to say, the present invention can be similarly applied to (Film Transistor).

〔Effect of the invention〕

According to the present invention, a doped layer with a band gap different from that of a thin film of Si alone and a very low resistance can be obtained.
It has the effect of greatly improving the characteristics of solar cells, photodiodes, etc.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view showing a second embodiment of the present invention. 1...Glass substrate, 2...Transparent electrode, 3...p type S
iC: 8 layers, 4...i-type amorphous Si: HpIj
, 5... N-type microcrystalline Si: HpIj, 6... Back electrode, 11... S tJ S substrate, 12... P-type amorphous Si: 8 layers. 13・I-type amorphous S i: 8 layers, 14...
N-type layer i O: 8 layers, 15...transparent electrode.

Claims (1)

[Claims] 1. In a semiconductor device whose main component is a non-single crystal silicon semiconductor containing hydrogen, at least one of the p-type or n-type semiconductor layers is composed of Si and H
An alloy that always contains at least one of C, N, and O, and has a dopant such as P or B, and the semiconductor layer is formed using a chemical vapor deposition method using light irradiation. , the conductivity of the semiconductor layer is 10^-^8Ω^-^1.
A method for manufacturing a semiconductor device, characterized in that the thickness is at least cm^-^1. 2. In the formation of the semiconductor layer, Si_nH is used as a Si source.
2. The method of manufacturing a semiconductor device according to claim 1, wherein _2_n_+_2_1 (n≧2) is used. 3. In the formation of the above semiconductor layer, Si_2H is used as a Si source.
6. The method of manufacturing a semiconductor device according to claim 1, wherein ultraviolet light including light having a peak wavelength of at least approximately 185 nm is used as a light source. 4. In a semiconductor device whose main component is a non-single-crystal silicon-based semiconductor containing hydrogen, at least one layer of the semiconductor layer always contains Si and H, and also contains C, N, and O.
A method for manufacturing a semiconductor device, characterized in that the semiconductor layer is formed using a chemical vapor deposition method using light irradiation, wherein at least one of the semiconductor layers is a microcrystalline alloy.