JPH08125214A - Manufacture of thin-film element - Google Patents

Abstract

PURPOSE: To improve manufacturing yield when filming each semiconductor film using each separate filming device in a method of manufacturing a thin-film element where i-type semiconductor film is laminated on n-type semiconductor film. CONSTITUTION: In the manufacturing method of a thin-film element for successively forming a first conductive film (metal electrode), an n-type semiconductor film consisting of amorphous silicon where phosphorus is doped, I-type semiconductor film consisting of amorphous silicon, and a second conductive film (transparent electrode), an n-type semiconductor film 12 is formed and then a film 13a for protecting interface consisting of the i-type semiconductor thin film which is thinner than the i-type semiconductor film is formed. Then, after breaking vacuum, an i-type semiconductor film 13b is formed on the film 13a for protecting interface, thus preventing an n-type semiconductor film 12 from being damaged due to the presence of the film 13a for protecting interface even if a surface treatment such as the elimination of natural oxide film is performed when changing the filming device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin film element, and more particularly to a method for manufacturing a sandwich type photodiode having a semiconductor film sandwiched between conductive films.

[0002]

2. Description of the Related Art Photodiodes as thin film elements are
It has a sandwich structure in which an n-type semiconductor film and an i-type (intrinsic) semiconductor film are sandwiched between conductive films. In this photodiode, Si (silicon) doped with P (phosphorus) is deposited on a glass substrate on which a metal film is deposited in advance to form an n-type semiconductor film. ) Consists of i
It is manufactured by depositing a type semiconductor film on an n-type semiconductor film and further depositing a metal film. In this case, the n-type semiconductor film and the i-type semiconductor film are usually formed by independent film forming devices.

The reason for depositing the n-type semiconductor film and the i-type semiconductor film by different film depositing devices is that each film depositing device can be used for a plurality of purposes by operating each film depositing device independently. This is because it can be used to improve production efficiency. Further, when the film is formed by the same film forming apparatus, the i-type semiconductor film may be contaminated by P (phosphorus) attached to the film forming jig, and the film is formed by another film forming apparatus. The above-mentioned contamination can be completely prevented.

[0004]

However, when the n-type semiconductor film and the i-type semiconductor film are formed by different film forming apparatuses, the i-type semiconductor film is exposed to the film in the step of forming the i-type semiconductor film. There was a case where a phenomenon in which air bubbles were generated. When the dome-shaped bubbles are generated, most of them are generated over the entire surface of the glass substrate, so that the production yield of the photodiode (thin film element) is remarkably reduced and the production is greatly affected.

The above phenomenon will be specifically described with reference to FIG. A metal thin film 21 is deposited on the glass substrate 20, the glass substrate 20 on which the metal thin film 21 is deposited is placed in a film deposition apparatus, and amorphous Si (silicon) doped with P (phosphorus) is deposited. By depositing the film, the n-type semiconductor film 2
2 is formed (FIG. 3A). After that, the glass substrate 20 is taken out from the film forming apparatus and placed in another film forming apparatus, and the i-type semiconductor film 23 made of amorphous Si (silicon) is formed, for example, at a substrate temperature of 200 degrees and a CVD pressure of 0.5 Torr. Film is deposited under the conditions. At this time, since the surface of the n-type semiconductor film 22 is released to the atmosphere, a natural oxide film is formed on the n-type semiconductor film 22 by the oxygen in the atmosphere as shown by an arrow A, or contamination is generated. It adheres. In order to remove such a natural oxide film and contamination, the surface treatment of the n-type semiconductor film is performed using a chemical such as buffered hydrofluoric acid (BHF) (FIG. 3 (b)).

However, if the surface of the n-type semiconductor film 22 is treated with buffered hydrofluoric acid (BHF), the surface of the n-type semiconductor film 22 may be locally damaged (FIG. 3C). ). As a result, the adhesive force between the n-type semiconductor film 22 and the i-type semiconductor film 23 is reduced, and the diameter of the interface between the n-type semiconductor film 22 and the i-type semiconductor film 23 is several μm to several mm as shown by an arrow B. Dome-shaped bubbles may occur (FIG. 3 (d)).

When such dome-shaped bubbles are generated,
The bubbles burst during the next step, causing a problem such as film peeling on the i-type semiconductor film 23, making it impossible to form a desired pattern (FIG. 3E). In addition, in order to improve the characteristics of the photodiode, the deposition condition of the i-type semiconductor film 23 may be changed. For example, the i-type semiconductor film 23
Substrate temperature of 250 degrees C
When the film is formed under the condition of VD pressure of 0.3 Torr, the film quality such as film stress of the i-type semiconductor film 23 is changed, and thus the damaged n-type semiconductor film 22 and i-type semiconductor film 23. Further, the adhesion force with and the generation rate of dome-shaped bubbles increased, which had a great influence on the manufacturing yield.

As one of the methods for avoiding the generation of such dome-shaped bubbles, for example, before deposition of an n-type semiconductor film (second semiconductor film) doped with P (phosphorus) A method for continuously depositing an i-type semiconductor film of the same type as the first semiconductor film has been proposed (see JP-A-11-11187). However, the above-mentioned method is a case where the i-type semiconductor film is used as the first semiconductor film, and the n-type semiconductor film (second semiconductor film) doped with P (phosphorus) is deposited thereon. , Buffed hydrofluoric acid (BHF) as described above
It does not solve the generation of bubbles due to local damage on the surface of the n-type semiconductor film (first semiconductor film) due to treatment or the like.

The present invention has been made in view of the above circumstances, and in the method of manufacturing a thin film element in which an i-type semiconductor film is laminated on an n-type semiconductor film, the respective semiconductor films are formed by different film forming devices. In this case, it is an object to provide a method capable of improving the manufacturing yield.

[0010]

In order to solve the above problems, the method of the present invention comprises a first conductive film, an n-type semiconductor film made of amorphous silicon doped with phosphorus, and amorphous silicon. In a method of manufacturing a thin film element, in which an i-type semiconductor film made of and a second conductive film are sequentially formed, after the n-type semiconductor film is formed, the i-type semiconductor thin film is thinner than the i-type semiconductor film. The interface protection film is formed, then the vacuum is broken, and then the i-type semiconductor film is formed on the interface protection film.

[0011]

According to the method of the present invention, after the n-type semiconductor film is deposited, the interface protection film made of the i-type semiconductor film is continuously deposited, and then the n-type semiconductor film deposition device is separately provided. Since the i-type semiconductor film is deposited on the interface protection film by the film deposition device of
Even if a surface treatment such as removal of a natural oxide film is performed when changing the film deposition apparatus, it is possible to prevent the n-type semiconductor film from being damaged by the presence of the interface protection film.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the method of manufacturing a thin film element of the present invention, a manufacturing process for manufacturing a photodiode will be described below with reference to FIGS. A Ti film having a thickness of 200 nm is deposited on the glass substrate 10 by a sputtering method to form a metal thin film 11 which will be a lower electrode of the photodiode. After the glass substrate 10 is thoroughly washed with ultrapure water or the like, a P (thickness of 0.1 μm is formed so that the photoelectric conversion layer 13b of the photodiode described later and the metal thin film 11 are in ohmic contact with each other. Amorphous Si (silicon) (n-type semiconductor film) 12 doped with phosphorus is deposited.

Here, the deposition of the n-type semiconductor film 12 is
For example, parallel plate type plasma CVD is used as follows. That is, the glass substrate 10 on which the metal thin film 11 is deposited is placed on the ground electrode side of the counter electrode of plasma, evacuated to about 10 ⁻² Pa, and then heated to a substrate temperature of about 250 ° C. After that, 1% P
The H ₃ / SiH ₄ gas was introduced into the chamber through a shower plate (gas introduction hole) provided on the RF electrode side of the counter electrode of the plasma while controlling the flow rate at 1000 SCCM.
Sufficiently stabilize the temperature while automatically adjusting the contactance valve to 39.9 Pa. After sufficient temperature and gas stabilization, the RF electrode is set to 1 at 13.56MHz.
RF power of 00 W is applied to generate plasma on the parallel plate electrodes, and the n-type semiconductor film 12 is deposited on the metal thin film 11 (FIG. 1A).

Next, the photoelectric conversion layer 13b of the photo diode described later is not broken without breaking the vacuum of the plasma CVD apparatus.
Non-doped amorphous Si (silicon) which is the same member as
The interface protection film 13a formed of (i-type semiconductor film)
The film is continuously deposited so that the film thickness is 12 nm. That is, 100% SiH ₄ gas is introduced into the chamber while controlling the flow rate to 1000 SCCM, and the gas is stabilized by automatically adjusting the conductance valve to 39.9 Pa. Then, 13.56MHz on the RF electrode,
An i-type semiconductor film interface protection film 13a is deposited on the n-type semiconductor film 12 with an RF power of 100 W. After that, the glass substrate 10 is moved from the reaction chamber to the extraction chamber, N ₂ is introduced into the extraction chamber to bring it to atmospheric pressure, and the glass substrate 10 is taken out from the CVD device (FIG. 1B).

Next, in order to remove the natural oxide film formed on the surface of the interface protection film 13a by taking it out into the atmosphere, hydrofluoric acid (HF) and ammonium hydrofluorate (NH ₄ ) are used.
F) has a volume ratio of 1: 200 buffered hydrofluoric acid (BH
F) is used to perform light etching on the surface of the interface protection film 13a on the glass substrate 10 for about 1 minute to 1 minute 30 seconds (FIG. 1).
(C)).

Next, while keeping the glass substrate 10 in an N ₂ atmosphere so as not to come into contact with the atmosphere, the glass substrate 10 is charged into the plasma CVD apparatus, and the glass substrate 10 is fixed to the ground electrode side of the counter electrode of plasma, and 10 ^{−2 is set.} The substrate is heated to a temperature of about 200 ° C. while being evacuated to about Pa. The film deposition is performed as follows, for example. 100% SiH ₄ gas is introduced into the chamber while controlling the flow rate to 1000 SCCM, and the temperature and gas are sufficiently stabilized by automatically adjusting the conductance valve to 66.5 Pa. After stabilizing sufficiently, 13.56M on the RF electrode
RF power of 150 W at Hz is applied to generate plasma in the parallel plate electrodes, and an i-type amorphous film having a thickness of 1.3 μm to be a photoelectric conversion layer of a photodiode is formed on the interface protection film 13a. A Si (silicon) (i-type semiconductor film) 13b is deposited. After that, the glass substrate 10 is moved from the reaction chamber to the extraction chamber, N ₂ is introduced into the extraction chamber to bring it to atmospheric pressure, and CVD is performed.
The glass substrate 10 is taken out from the device (FIG. 1 (d)). Next, an ITO film having a thickness of 60 nm is deposited on the i-type semiconductor film 13b by a sputtering method to form a transparent conductive film 14 which will be an upper electrode of the photodiode (FIG. 1).
(E)).

A desired resist pattern is formed on the laminated film in which the metal thin film 11, the n-type semiconductor film 12, the interface protection film 13a, the i-type semiconductor film 13b, and the transparent conductive film 14 are sequentially formed on the glass substrate 10 by the above steps. 15 to form (Fig. 2
(A)), the transparent conductive film 14 is etched using hydrochloric acid (HCl) diluted 1: 7 with pure water (FIG. 2).
(B)). Further, the interface protection film 13a and the i-type semiconductor film 13
The three layers of the b and n-type semiconductor films 12 are simultaneously formed into SF ₆ , C ₂ HCl.
Dry etching is performed using ₂ F ₃ and O ₂ gas (see FIG. 2).
(C)). Then, the resist pattern 15 is stripped using O ₂ plasma ashing and a resist stripping solution,
A desired island-shaped photo diode shape is obtained (FIG. 2).
(D)).

Finally, a photoresist pattern for forming a pattern of the metal thin film 11 which will be the lower electrode of the photo diode is newly formed and the metal thin film 11 is etched to form a photo diode. Is completed.

In this embodiment, the thickness of the interface protective film 13a composed of the i-type semiconductor thin film is set to 12 nm, but the n-type semiconductor film 12 causes local damage due to buffered hydrofluoric acid (BHF). The film thickness may be enough to avoid it. The i-type semiconductor film 13b is for generating carriers by irradiation light, and has a film thickness of 1.3 μm in this embodiment. Further, this film thickness is preferably 500 nm or more in consideration of the spectral sensitivity characteristic.
That is, the film thickness of the i-type semiconductor film 13b corresponds to the film thickness of the i-type semiconductor film 23 in the conventional example of FIG. 3, and therefore, as the i-type semiconductor layer, the interface protection film 13a.
The i-type semiconductor thin film becomes thicker.

Further, according to the above manufacturing method, since the interface protection film (i-type semiconductor thin film) 13a is deposited by the same film deposition apparatus as the n-type semiconductor film 12, the interface protection film 13a is formed by P
Although it may be contaminated by (phosphorus), the film thickness of the interface protection film 13a is as thin as 12 nm, and the photoelectric conversion layer of the photodiode is formed of the i-type semiconductor film 13b. Will not be adversely affected.

[0021]

According to the present invention, after depositing an n-type semiconductor film, an interface protection film made of an i-type semiconductor film is continuously deposited, and thereafter, an n-type semiconductor film deposition apparatus is provided. Since the i-type semiconductor film is deposited on the interface protection film by another film deposition device,
Even if a surface treatment such as removal of a natural oxide film is performed when changing the film deposition apparatus, it is possible to prevent the n-type semiconductor film from being damaged by the presence of the interface protection film. Therefore, the n-type semiconductor film and i
It is possible to prevent the formation of dome-shaped bubbles between the semiconductor film and the semiconductor layer, and to improve the yield in the production of thin film elements.

[Brief description of drawings]

1 (a) to 1 (e) are cross-sectional explanatory views showing a part of a manufacturing process of a thin film element by the method of the present invention.

2 (a) to 2 (d) are cross-sectional explanatory views showing a part of a manufacturing process of a thin film element by the method of the present invention.

3 (a) to 3 (e) are cross-sectional explanatory views showing a part of a conventional manufacturing process of a thin film element.

[Explanation of symbols]

Reference numeral 10 ... Glass substrate, 11 ... Metal thin film (first conductive film), 12 ... N-type semiconductor film, 13a ... Interface protection film, 13b ... i-type semiconductor film, 14 ... Transparent conductive film (second conductive film) , 15 ... Resist pattern

Claims (1)

[Claims] 1. A first conductive film, an n-type semiconductor film made of amorphous silicon doped with phosphorus, an i-type semiconductor film made of amorphous silicon, and a second conductive film are sequentially formed. In the method of manufacturing a thin film element to be formed, after forming the n-type semiconductor film, an interface protection film made of an i-type semiconductor film thinner than the i-type semiconductor film is formed, and then, after breaking the vacuum, the interface is formed. A method of manufacturing a thin film element, comprising forming the i-type semiconductor film on a semiconductor film.