JPH0682856B2 - Semiconductor device manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention provides a substrate having an insulating surface with a non-single crystal semiconductor including an amorphous semiconductor having at least one junction capable of generating a photoelectromotive force by light irradiation. Further, the present invention relates to a method for manufacturing a photoelectric conversion device capable of generating a high voltage in which a plurality of photoelectric conversion elements (also simply referred to as elements) are electrically connected in series.

"Prior Art" Conventionally, an amorphous semiconductor is known as a non-single-crystal semiconductor to which hydrogen or a halogen element is added. However, since such a semiconductor has an amorphous structure and does not actively use the crystallinity, the carrier depletion layer of the I-type semiconductor layer in the PIN junction is as narrow as 0.3 μ or less, and the AM1.5
The depletion layer became shorter due to the light irradiation at (100 mW / cm ² ) and the deterioration occurred.

“Problems to be Solved by the Present Invention” With respect to a non-single-crystal semiconductor including such an amorphous semiconductor, crystallization is promoted in an active I-type semiconductor region that generates electrons and holes by light irradiation, and a particularly long wavelength is obtained. It is required to improve the light collection efficiency and the conversion efficiency. Further, in the photoelectric conversion device having the PIN junction, the width of the depletion layer in the I-type semiconductor is increased to 1 μm or more, and the connecting portion for integration is not crystallized but has a high resistance of an amorphous structure. It is required to leave the region as it is and prevent the occurrence of leakage through the semiconductor in this region.

"Means for Solving the Problem" The present invention provides a pulsed intense light (pulse width 10 nm or less) with a wavelength of 400 nm or less from a back electrode side to a non-single crystal semiconductor before or after forming an N-type or P-type semiconductor layer. ˜100 nsec) to promote crystallinity while preserving hydrogen or a halogen element inside the I-type semiconductor layer or this I-type semiconductor layer and the N- or P-type semiconductor layer on the back surface side close to the I-type semiconductor layer. Is.

As a result, for semiconductors containing silicon as the main component, 1.
The energy band width can be narrower than 3-1.6 eV and 1.7-1.8 eV of an amorphous semiconductor. Therefore, it becomes possible to improve the collection efficiency of long-wavelength light.

In particular, the present invention has a small light absorption of 400 nm or less, for example, KrF.
Alternatively, the pulsed intense light of an excimer laser using XeCl is used to form the crystallinity of the I-type semiconductor in a sufficiently deep internal region (on the back electrode side opposite to the light irradiation surface), and then from the back surface side. It was irradiated and accelerated, and so-called optical annealing was performed. Therefore, the light used has a wavelength of 400 nm or less, which has a relatively large light absorption coefficient of the semiconductor.

The present invention is a further improvement of a patent application filed by the present inventor (Japanese Patent Application No. Sho 59-181097 semiconductor device, filed on August 24, 1984).

According to the present invention, this photo-annealing should not allow the leakage in the peripheral portion due to the increase in the electrical conductivity which accompanies at the same time. Therefore, in the integrated structure, the isolation at the connecting portion should not be hindered. Therefore, in the present invention, this optical annealing is performed only on the region forming the photoelectric conversion element.

[Operation] As a result, since the crystallization promoting region obtained by laser annealing is not performed on the isolation region between each cell (element) and its outer periphery, it does not affect other manufacturing processes of the integrated photoelectric conversion device. It has the feature that it can be completed without any extra steps.

The arrangement, size and shape of the elements in the device of the present invention are determined by design specifications. However, in order to simplify the content of the present invention, in the following detailed description, the first electrode on the lower side (substrate side) of the first element and the second electrode of the second element arranged on the right side of the first electrode will be described. The electrode (on the semiconductor, that is, the rear surface side away from the substrate) of No. 1 is electrically connected in series to the pattern.

The defined position is irradiated with an excimer laser using KrF or XeCl, for example, a wavelength of 248 nm. The present invention, the substrate is formed on a translucent glass semiconductor, to the light irradiation side of the upper surface, the laser light annealing of 400nm or less from the back side is performed, without increasing the manufacturing process An object of the present invention is to provide an epoch-making photoelectric conversion device manufacturing method capable of increasing the yield to 87% from the conventional 60%.

The present invention will be described in detail below with reference to the drawings.

Example 1 FIG. 1 is a vertical sectional view showing a manufacturing process of the present invention.

In FIG. 1 (A), a substrate having an insulating surface, for example, a glass substrate (1), having a length (horizontal direction in the drawing)
10 cm and a width of 10 cm were used. Further, a first conductive film (2) is formed on the entire upper surface of the transparent conductive film in an amount of 0.1 to 0.5.
It was formed to a thickness of μ.

As the transparent conductive film (2), a transparent conductive film containing tin oxide as a main component to which a halogen element such as fluorine is added, or
ITO (tin oxide indium) (500 to 5000Å, typically 500 to 1500Å) was formed by a sputtering method or a spray method.

After this, from the upper side of this substrate, YAG laser (wavelength 1.06μ
m (Pulse width 80nsec) processing machine (made by NEC) with average output 0.3 to 3W (focal length 40mm), condensing laser light with diameter 5mmφ, spot diameter 20 to 70μφ typically 40μ
φ is controlled by a microcomputer to irradiate a laser beam from above, and the scanning thereof forms a first open groove (13) for a scribe line, and each element region (31),
The first electrode (15) was formed on (11) by laser scribing (referred to as LS).

The groove (13) formed by LS has a width of about 50 μm and a length of 10 cm, and the depth of each groove is completely cut and separated to form the first electrode.

Thus, the width of the regions forming the first element (31) and the second element (11) was set to 5 to 40 mm, for example 10 mm.

After this, plasma CVD method, photo CVD method or
Non-single-crystal semiconductors that generate photoelectromotive force by light irradiation by the LPCVD method, that is, PIN junction, NIP junction, or PI junction or
The non-single-crystal semiconductor layer (3) having an NI junction and added with hydrogen or a halogen element has a minimum oxygen concentration of 5 × 10 ¹⁸ cm ⁻³ or less in the I-type semiconductor and a thickness of 0.3 to 3.0. μ was typically formed to 1.5 μ.

The first representative example is the case where the light irradiation is from the substrate side, so a P-type (SixC _1-x 0 <x <1) semiconductor (about 200Å)
-I type amorphous silicon semiconductor (about 1.5μ) -One PIN consisting of semiconductor with N type microcrystal (about 500Å)
The non-single crystal semiconductor (3) having a junction was formed over the entire surface with a uniform film thickness.

In the second representative example, a non-single-crystal semiconductor (3) having one PI junction having a P-type semiconductor-I-type amorphous semiconductor is formed over the entire surface.

Further, an outline of excimer laser light annealing for emitting ultraviolet light having a wavelength of 400 nm or less in the method of the present invention will be shown.

The irradiated semiconductor is shown in FIG. A semiconductor before or after forming the N-type semiconductor forming the PIN junction (after forming the PI junction, that is, the second representative example) or after (forming the PIN junction after forming the PIN junction, that is, the first representative example) in an optical annealing step Used as.

This object was stored in vacuum or in a hydrogen atmosphere, and pulsed light was externally applied to the object through a synthetic quartz window.

An excimer pulse laser beam with an irradiation light area of the light source of 120 mm ² was used. In particular, this width is the same as the width of the region that constitutes the element, and irradiation to the same part is performed by repeating the irradiation of pulsed light once or less than 10 times, moving the irradiation part, and irradiating the entire area that constitutes the element with light. Annealed.

Here, an excimer laser oscillator manufactured by KESTECH was used.

This laser light is focused by a lens and has a rectangular shape of 10 mm ×
Pulsed light with an area of 12 mm (repetition frequency 30 Hz to 300 Hz)
Was used. This irradiation width is the element area (11), (3
I made it match the width of 1).

This irradiation light (25) was irradiated onto the substrate to be moved at a constant speed on the surface to be irradiated.

By doing so, it was possible to crystallize a region having a depth of 0.1 to 0.4 μm, which is a part of the thickness of the back surface electrode side of the I layer in the non-single crystal semiconductor. The fact of this crystallization was revealed by performing laser Raman spectroscopy after this step. in addition,
Since the annealing according to the method of the present invention is an optical pulse annealing having a short pulse width of 10 to 50 nsec, hydrogen or halogen elements already contained are hardly degassed during crystallization. In addition, since the crystallinity or order is promoted by photo-annealing, the photo-degradation property is reduced, and in addition, the PI
It has a dual feature that the width of the depletion layer in the I layer between the two can be extended to 1 to 3 μ from 0.3 μ in the PIN junction having an amorphous structure. Therefore, the optimum thickness of the I layer is 0.5 μm when only the amorphous semiconductor is used in the I layer.
Due to the composite structure with a semiconductor having higher crystallinity, 0.5 to
It can be made as thick as 2.0 μm, short wavelength light is absorbed in amorphous silicon semiconductor regions (35-1), (35'-1), and long wavelength light is polycrystalline silicon semiconductor region (35-2), By absorbing at (35'-2), it became possible to perform photoelectric conversion over a wide wavelength range. As a result, the current of the photoelectric conversion device can be increased.

This laser light annealing is the regions (31) and (11) constituting the device in FIG. 1 (C) (35-2) and (35 ').
-2) only. The region forming the connecting portion (4) is a high resistance semiconductor, particularly an amorphous semiconductor,
The electrodes (39), (3
I tried not to leak between 9 ').

Further, this laser annealing is performed within 1 to 2 mm from both end portions in the width direction of the element (end portions in the front-rear direction in the drawing) so as not to reach both end portions. As a result, the regions (31) and (11) forming the element are made to remain in the amorphous semiconductor in all of the outer peripheries of the polycrystallized regions (35-2) and (35'-2). In other words, the outer peripheral portion of the region constituting the element is surrounded by the amorphous semiconductor of high resistance, and thus the semiconductors (35-2), (35'-
It was possible to prevent the leakage between the upper and lower electrodes in the peripheral part of 2), that is, the reduction of the series resistance in the equivalent circuit.

Further, in the first example of the present invention, after this laser annealing, as shown in FIG. 1 (B), the second groove is formed on the left side (first element side) of the first groove (13).
The open groove (14) was formed by the second LS process. In this drawing, the centers of the first and second open grooves (13) and (14) are
It is shifted by 100μ.

Thus, the second groove (14) exposed the side surface (8) of the first electrode.

Further, in the second example, since only the PI junction was formed, an N-type semiconductor was formed thereon by the plasma CVD method to form a PIN junction semiconductor. Subsequently, the open groove (14) was formed as described above.

In FIG. 1, a second conductive film (5) on the surface was further formed on this upper surface as shown in FIG. 1 (C).

Furthermore, after this, the third LS cuts and separates to form a plurality of second electrodes (39) and (39 ') for forming a third groove (20).
Was formed and isolated.

This second conductive film (5) is made of metal and a transparent conductive oxide film (CT).
A multilayer film with F) was used. The thickness is 300-1500 respectively
Å formed.

As the CTF, a translucent conductive film made of a non-oxide conductive film such as a chromium-silicon compound may be used.

These are electron beam evaporation method or sputtering method, photo CV
A CVD method including a D method and a photo-plasma CVD method was used to form the semiconductor layer at a temperature of 250 ° C. or lower so as not to deteriorate the semiconductor layer.

Thus, as shown in FIG. 1 (C), a photoelectric conversion device in which a plurality of elements (31) and (11) are connected in series at the connecting portion (4) could be manufactured.

FIG. 1 (D) further completes the present invention as a photoelectric conversion device. That is, a silicon nitride film (21) is uniformly formed to a thickness of 500 to 2000Å as a passivation film by the plasma vapor phase method or the photo plasma vapor phase method, and the leakage current between the elements is generated by adsorption of moisture or the like. Was further prevented.

FIG. 2 shows an energy band diagram in a vertical sectional view taken along the line AA ′ in FIG. 1 (D). Drawing shows light irradiation (1
The (0) plane side has a P-type semiconductor (6), and has an amorphous semiconductor (35-1) and a polycrystalline semiconductor (35-2).

Therefore, the I-type semiconductor has an amorphous semiconductor (7-1) and a polycrystalline semiconductor (7-2), and an N-type semiconductor is placed behind it.
It constitutes a type semiconductor (8). Polycrystalline semiconductor (7-2)
It had a thickness of 0.1-0.4μ and was effective in absorbing long-wavelength light.

This N-type semiconductor may be formed with an amorphous or microcrystalline structure after photoannealing. This increases the number of steps. However, it is possible to prevent local diffusion into the N-type semiconductor and the I-type semiconductor due to the optical annealing, and the yield is improved.

Furthermore, external lead-out terminals (24) and (24 ') are provided in the peripheral area.

Thus, with respect to the irradiation light (10), the substrate (10 cm × 10 cm) as in this example is provided on a strip with a width of 10 mm × 92 mm of each element, and the width of the connecting portion is 150 μm. mm, and the peripheral portion 4 mm, there are substantially 9 steps within 88 mm × 92 mm.

As a result, when the segment had a conversion efficiency of 12.2% (1.05 cm ² ), it was possible to have 10.4% in the panel by means of a 9-stage series connection resistor.

"Effect" The present invention improves the collection efficiency of long-wavelength light by performing laser annealing before or after the formation of the N or P type semiconductor layer, which is a step after the formation of the I type semiconductor, and thus improves the conversion efficiency. Let Further, at that time, since the same amorphous structure as that in the initial stage was retained in the connecting portion and the peripheral portion, it was possible to prevent the resistance from being lowered due to the crystallization of the semiconductor here and further prevent the increase of the leak current.

In addition, by polycrystallizing only the internal semiconductor on the side opposite to the incident light, while maintaining a high current density there, it is completely difficult to integrate the amorphous photoelectric conversion device. I was able to achieve it without losing its characteristics.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a manufacturing process of a photoelectric conversion device of the present invention. FIG. 2 shows the energy band width corresponding to the longitudinal section of AA 'of the present invention. 1 ... Transparent substrate 2 ... Transparent conductive film 3 ... Non-single crystal semiconductor 31,11 ... Photoelectric conversion element 4 ... Coupling 35-1,35'-1 ... Amorphous semiconductor 35-2 , 35'-2 …… Polycrystalline semiconductor 25 …… Excimer laser light 10 …… Irradiation light 6 …… P-type semiconductor 7-1 …… Amorphous I-type semiconductor 7-2 …… Polycrystalline I-type semiconductor 7 …… I Type semiconductor 8 …… N type semiconductor 5 …… Backside electrode conductor

Claims (4)

[Claims] 1. A method for manufacturing a photoelectric conversion device having a structure in which a plurality of photoelectric conversion elements are integrated, comprising: a substrate having an insulating surface; a first electrode; A step of forming a non-single-crystal semiconductor having an NI junction added with hydrogen or a halogen element, and irradiating the semiconductor with pulsed intense light from the back surface side opposite to the substrate to perform optical annealing to perform an I-type semiconductor Of crystallization, a step of forming an N or P-type semiconductor by stacking, and a step of forming a second electrode after the step, and adjacent photoelectric conversions are performed during the optical annealing. A method for manufacturing a semiconductor device, characterized in that a region for connecting elements is not annealed by light. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the optical annealing uses an excimer laser having a wavelength of 400 nm or less. 3. A step of forming, on a substrate having an insulating surface, a first electrode, and a non-single-crystal semiconductor doped with hydrogen or a halogen element having a PI or NI junction in close contact with the first electrode, A step of irradiating the semiconductor with pulsed strong light from the back surface side opposite to the substrate to perform optical annealing to crystallize the I-type semiconductor; and a step of stacking and forming an N-type or P-type semiconductor, And a step of forming a second electrode after the step. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the optical annealing uses an excimer laser having a wavelength of 400 nm or less.