JPH077752B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device using a semiconductor amorphous film containing a dopant, and more specifically, to a semiconductor amorphous film containing a dopant having a low resistance. The present invention relates to a method for manufacturing a semiconductor device suitable for manufacturing.

[Background of the Invention]

In semiconductor devices using semiconductor amorphous films such as amorphous silicon solar cells and thin film transistors,
Conventionally, since the semiconductor amorphous film has a high resistance, there has been a problem that a semiconductor device having excellent characteristics cannot be manufactured. In order to solve such a problem, the following three methods have been conventionally proposed.

The first method is plasma vapor deposition (hereinafter referred to as plasma CVD
It is intended to reduce the resistance of the formed semiconductor amorphous film by adjusting the plasma generation conditions and atmospheric gas conditions when forming the semiconductor amorphous film (Journal of Electronic Materials 11 , 749,1).
982).

The second method is to introduce a hydrogen gas while forming a semiconductor amorphous film by plasma CVD to reduce the resistance of the semiconductor amorphous film formed by the action of hydrogen plasma (Solid-State Electronics). 11 , 683,1968).

The third method is to reduce the resistance of the semiconductor amorphous film by annealing the semiconductor amorphous film at a high temperature of 700 ° C. or higher.

However, the above-mentioned first method and second method have a problem in that it is necessary to carefully set various conditions, which requires a great deal of time and labor. Further, in the third method, since the entire semiconductor device is heated at a high temperature of 700 ° C., the adverse effect of the heating on a portion other than the semiconductor amorphous layer (eg
There is a problem that defects occur in the crystal structure).

[Object of the Invention]

The present invention has been made in view of the above-mentioned problems of the conventional technique, and it is possible to easily reduce the resistance of a semiconductor amorphous film containing a dopant without adversely affecting a portion other than the semiconductor amorphous film such as defect generation. It is an object of the present invention to provide a method for manufacturing a semiconductor device.

[Outline of Invention]

The method for manufacturing a semiconductor device of the present invention is performed by applying excimer laser light (ultraviolet pulsed laser light) having a wavelength of 150 nm to 370 nm to a semiconductor amorphous film containing a dopant at 0.05 J / cm ² to 2.0 J / cm ^2.
Irradiation is performed with a laser energy density of ² .

It is known that when a semiconductor amorphous film is irradiated with laser light, the semiconductor amorphous film can be crystallized or crystal defects can be removed.
A continuous wave laser beam in the visible to infrared region such as a laser has been used.

On the other hand, the present inventors have found that when excimer laser light with a wavelength of 150 nm to 370 nm which is a pulsed laser light in the ultraviolet region with good absorption efficiency is used, a phenomenon completely different from the conventional one occurs. That is, when the semiconductor amorphous film is irradiated with excimer laser light having a wavelength of 150 nm to 370 nm,
Since it absorbs energy instantaneously and does not supply energy for a certain period of time, the movement of silicon necessary for crystallization and removal of crystal defects does not occur easily, but the dopant that can move relatively freely can move and be activated. It was found that the resistance of the semiconductor amorphous film can be lowered by reducing the resistance.

In that case, it was confirmed that the excimer laser light used had a laser energy density in the range of 005 J / cm ² to 2.0 J / cm ² and that the semiconductor amorphous film containing the dopant could have a good resistance reduction. That is, the best laser energy density depends on the type of substrate used,
Generally, in the range where the laser energy density is 0.15 J / cm ² or less, crystallization of the semiconductor amorphous film is difficult to occur, but activation of the dopant reduces the resistance to 0.15 J / cm ²
Within the above range, the activation of the dopant and the crystallization of the semiconductor amorphous film work together to reduce the resistance. When the laser energy density is 0.05 J / cm ² or less, the laser energy density is too low to reduce the resistance of the semiconductor amorphous film, and when the laser energy density is 2.0 J / cm ² or more, the laser energy density is too high and the semiconductor amorphous layer. Was confirmed to be destroyed.

Irradiation of excimer laser light (ultraviolet pulse laser light) may be performed in air, vacuum, or an inert gas, and it has been confirmed that the semiconductor amorphous film has a sufficiently low resistance.

It was also confirmed that the substrate temperature was room temperature, and that the substrate may be heated at a low temperature.

Example of Invention

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention. As shown in the figure, an amorphous film 2 was formed on the glass substrate 1 by the plasma CVD method, and the ultraviolet laser light a having a wavelength of 150 nm to 370 nm was irradiated to reduce the resistance of the amorphous silicon film.

Specific Examples 1 to 5 Specific Examples 1 to 5 shown in Table 1 form a boron-doped N-type amorphous silicon film as the amorphous film 2 and use KrF excimer laser light having a wavelength of 248 nm as the ultraviolet laser light a. Laser energy density 0.05 J / cm ^{2 to} 2.0 J / cm ²
It shows the change in conductivity when irradiated with.

As is clear from Table 1, it was confirmed that the conductivity was significantly improved before and after the irradiation with the KrF excimer laser light, and the resistance of the N-type amorphous silicon film was significantly reduced.

Specific Examples 6 to 10 In Specific Examples 6 to 10 shown in Table 2, a phosphorus-doped P-type amorphous silicon film is formed as the amorphous film 2, and KrF excimer laser light having a wavelength of 248 nm is used as the ultraviolet laser light a. Laser energy density 0.05 J / cm ^{2 to} 2.0 J / cm ²
It shows the change in electric conductivity when irradiated with.

As is clear from Table 2, it was confirmed that the conductivity was significantly improved before and after the irradiation with the KrF excimer laser light, and the resistance of the P-type amorphous silicon film was significantly lowered.

What is particularly noteworthy is that the activation of the dopant occurs independently of the microcrystallization, and the resistance of the P-type amorphous silicon film is significantly reduced.

FIGS. 3 to 5 are data for demonstrating this point. FIG. 3 shows the half width of the Si (111) peak obtained by the X-ray diffraction method for the samples shown in the specific examples 6 to 10. FIG. 4 is a diagram showing the relationship between the polycrystalline grain size and the irradiation laser energy density obtained from FIG. 4, and FIG. 4 shows the transmitted light intensity and irradiation in the wavelength range of 500 to 700 nm for the samples shown in the specific examples 6 to 10. FIG. 5 is a diagram showing a relationship between energy densities, and FIG. 5 is a diagram showing a relationship between conductivity and irradiation laser energy density when an amorphous silicon film containing no dopant is irradiated with laser.

As shown in FIG. 3, as long as the measurement is performed by the X-ray diffraction method, a peak showing crystallinity is not found in the irradiation with a laser energy density of 0.15 J / cm ² or less, and a polycrystalline grain size is observed with an irradiation energy higher than that. It shows how it grows.
Similarly, in FIG. 4, the laser energy density is 0.15 J /
It is shown that there is no change in the translucency with irradiation of cm ² or less, and the translucency sharply decreases with irradiation energy higher than that.

From the above data, it is reported that crystallization progresses at a laser energy density of 0.15 J / cm ² or more and contributes to the improvement of conductivity, but crystallization occurs at a laser energy density of 0.15 J / cm ² or less. Despite not being present, specific examples in Table 2
It is concluded that the conductivity is improved as shown in (3) because the dopant is activated. This can be explained from the behavior of the amorphous silicon film containing no dopant shown in FIG.
No improvement in conductivity is observed below 0.15 J / cm ² .

What I would like to emphasize especially here is the laser energy density.
This means that activation of the dopant occurs even with irradiation of 0.15 J / cm ² or more. That is, comparing FIG. 5 with the examples shown in Table 2 of the present invention, in the case of FIG. 5 containing no dopant, the conductivity was improved by only about 3 digits, whereas in the present example, ~ 6 digit improvement was seen.
That is, the mere crystallization alone provides only an improvement of about 3 digits, whereas the present invention shows that the addition of 2 to 3 digits is achieved due to the activation of the dopant. This means that the improvement in conductivity obtained by the present invention is caused in part by the crystallization of the amorphous film, but activation of the dopant occurs over the entire irradiation energy density, and the activation of the dopant and the amorphous film The crystallization can be combined to significantly improve the conductivity.

Specific Examples 11 to 15 Specific Examples 11 to 15 shown in Table 3 form a boron-doped N-type amorphous silicon film as the amorphous film 2 and use ArF excimer laser light having a wavelength of 193 nm as the ultraviolet laser light a. It shows the change in conductivity when irradiated with an energy density of 0.05 J / cm ^{2 to} 2.0 J / cm ² .

As is clear from Table 3, it was confirmed that the conductivity was significantly improved before and after the irradiation with the ArF excimer laser light, and the resistance of the N-type amorphous silicon film was significantly lowered.

Concrete Examples 16 to 20 Concrete Examples 16 to 20 shown in Table 4 form a phosphorus-doped P-type amorphous silicon film as the amorphous film 2 and use ArF excimer laser light having a wavelength of 193 nm as the ultraviolet laser light a. Laser energy density 0.05 J / cm ^{2 to} 2.0 J / cm ²
It shows the change in electric conductivity when irradiated with.

As is clear from Table 4, it was confirmed that the conductivity was significantly improved and the resistance of the P-type amorphous silicon film was significantly lowered before and after the irradiation with the ArF excimer laser light.

Specific Examples 21 to 23 In Specific Examples 21 to 23 shown in Table 5, a boron-doped N-type amorphous silicon film is formed as the amorphous film 2 and XeCl excimer laser light having a wavelength of 308 nm is used as the ultraviolet laser light a. Laser energy density 0.1 J / cm ^{2 to} 1.5 J / cm ²
It shows the change in electric conductivity when irradiated with.

As is clear from Table 5, it was confirmed that the conductivity was significantly improved and the resistance of the N-type amorphous silicon film was significantly lowered before and after the irradiation with the XeCl excimer laser light.

Specific Examples 24 to 26 Specific Examples 24 to 26 shown in Table 6 form a phosphorus-doped P-type amorphous silicon film as the amorphous film 2 and use XeCl excimer laser light having a wavelength of 308 nm as the ultraviolet laser light a. Laser energy density 0.1 J / cm ^{2 to} 1.50 J / cm
^It shows the change in conductivity when irradiated with ² .

As is clear from Table 6, it was confirmed that the conductivity was significantly improved and the resistance of the P-type amorphous silicon film was significantly lowered before and after the irradiation with the XeCl excimer laser light.

Specific Examples 27 to 29 Specific Examples 27 to 29 shown in Table 7 form a boron-doped N-type amorphous silicon film as the amorphous film 2 and use XeF excimer laser light having a wavelength of 351 nm as the ultraviolet laser light a. Laser energy density 0.1 J / cm ² to 1.5 J / cm ²
It shows the change in electric conductivity when irradiated with.

As is clear from Table 7, it was confirmed that the conductivity was significantly improved and the resistance of the N-type amorphous silicon film was significantly decreased before and after the irradiation with the XeF excimer laser light.

Specific examples 30 to 32 Specific examples 30 to 32 shown in Table 8 are those in which a phosphorus-doped P-type amorphous silicon film is formed as the amorphous film 2, and XeF excimer laser light having a wavelength of 351 nm is used as the ultraviolet laser light a. It shows the change in conductivity when irradiated with a laser energy density of 0.1 J / cm ^{2 to} 1.5 J / cm ² .

As is clear from Table 8, it was confirmed that the conductivity was significantly improved and the resistance of the P-type amorphous silicon film was significantly reduced before and after the irradiation with the XeF excimer laser light.

In the above-mentioned specific examples 1 to 32, the resistance of the amorphous film 2 was confirmed to be low, and further, the energy band width was reduced due to the polycrystallization of the amorphous film 2.

FIG. 2 is a diagram showing a second embodiment of the present invention. As shown in the figure, a transparent electrode 4 is formed on the glass substrate 3 by vapor deposition, and then phosphorus is doped by a plasma CVD method to form P.
An amorphous silicon layer 5, an i-amorphous silicon layer 6 without any doping, and an N-type amorphous silicon layer 7 by doping with boron. Then, on the N-type amorphous silicon layer 7, the concrete examples 33 to 33 in Table 9 are formed.
As shown in 36, laser energy density of 0.2 J / cm was used for each of ArK excimer laser (Example 33), KrF excimer laser (Example 34), XeCl excimer laser (Example 35) and XeF excimer laser (Example 36). Irradiate with ² . Then, the aluminum electrode 8 was formed by vapor deposition to manufacture a photoelectric converter, and the photoelectric conversion characteristics were measured. Specific examples 33 to 39 in Table 9 show the measurement results.

As is clear from Table 9, the specific examples 33 to 36 in which the excimer laser light is irradiated are more open-circuit voltage, short-circuit current, and curve than the comparative example in which the N-type amorphous silicon layer 7 is not irradiated with the excimer laser light. Both the factor and the photoelectric conversion efficiency showed high values. Here, the fill factor is the value of the area enclosed by the curve showing the current-voltage characteristics of the photoelectric converter and the current axis and the voltage axis, and the value of (open circuit voltage) x (short circuit current). And the ratio. In the above specific examples 1 to 36, the amorphous silicon film is used as the semiconductor amorphous film, but the present invention is not limited to this and can be applied to all semiconductor amorphous films.

〔The invention's effect〕

As is clear from the above description, according to the present invention, it is possible to easily reduce the resistance of only the semiconductor amorphous layer without adversely affecting the portion other than the semiconductor amorphous film such as the defect generation. Since the energy band width of the amorphous layer can be changed according to the purpose, the characteristics of the manufactured semiconductor device can be significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG. 2 is a diagram showing a second embodiment of the present invention. 3 to 5 are data for demonstrating the effect of the present invention, and FIG. 3 shows the Si (111) peaks obtained by X-ray diffraction for the samples shown in Examples 6 to 10. FIG. 4 is a diagram showing the relationship between the polycrystal grain size obtained from the half-width and the irradiation energy density. FIG. 4 shows the transmitted light intensity and irradiation in the wavelength range of 500 to 700 nm for the samples shown in specific examples 6 to 10. FIG. 5 is a diagram showing the relationship with the energy density, and FIG. 5 is a diagram showing the relationship between the conductivity and the irradiation laser energy density when the amorphous silicon film containing no dopant is irradiated with the laser. 1, 3 ... Glass substrate, 2 ... Amorphous film, 4 ... Transparent electrode, 5 ... P-type amorphous silicon layer, 6 ... i-Amorphous silicon layer, 7 ... N-type amorphous silicon layer,
8 ... Aluminum electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Tanaka, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Hitachi, Ltd. Institute of Industrial Science (72) Inventor Kazufumi Higashi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd., Production Engineering Laboratory (72) Inventor Mitsuo Nakatani, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture, Ltd. Production Engineering Laboratory, Hitachi (72) Inventor Tadashi Saito 1-280, Higashi Koigakubo, Kokubunji, Tokyo Address: Central Research Laboratory, Hitachi, Ltd. (56) Reference JP-A-58-56409 (JP, A) JP-A-57-155726 (JP, A)

Claims (2)

[Claims] 1. A dopant is activated by irradiating a semiconductor amorphous film containing a dopant with excimer laser light (ultraviolet pulsed laser light) having a wavelength of 150 nm to 370 nm at a laser energy density of 0.05 J / cm ² to 2.0 J / cm ² . A method for manufacturing a semiconductor device, comprising: 2. The semiconductor device according to claim 1, wherein the excimer laser light is ArF excimer laser light, KrF excimer laser light, Xecl excimer laser light, or XeF excimer laser light. Method.