JPH05121776A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor device provided with a photodiode, where an antireflection film small in reflectivity variation can be formed without increasing a manufacturing process. CONSTITUTION:Antireflection films 12, 16, and 20 are provided to the photodetective section of the photodiode of a semiconductor device, where the antireflection films concerned are formed of silicon nitride. In the semiconductor device, an SiO2 layer 10 is formed on a silicon substrate 1, and the SiO2 layer formed on the photodetective section of the photodiode is selectively etched. A silicon nitride film 12 is deposited on the SiO2 layer 10 and the photodetective section, and then a first process where the silicon nitride film 12 is selectively etched to form a MIS capacitive section, a second process where an interlayer insulating film 16 of silicon nitride is deposited, and a third process where an overcoat layer 20 is formed by depositing a silicon nitride film are provided for the formation of a semiconductor device of this design.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a photodiode section.

[0002]

2. Description of the Related Art Conventionally, compact disc players,
A semiconductor device having a pn junction or pin junction photodiode portion is used for a video disc player and various remote controls.

In a semiconductor device having a photodiode section, an antireflection film having a low reflectance is required in the light receiving section of the photodiode section. The reflectance is determined by the refractive index of the antireflection film, the absorption coefficient, and the wavelength of incident light. Further, the reflectivity also changes due to the film thickness variation of the antireflection film in the manufacturing process of the semiconductor device. When the antireflection film has a multi-layered structure of two or more layers, the fluctuation of the reflectance is large due to the fluctuation of each film thickness, as compared with the case of the antireflection film of the single layer structure.

Conventionally, the antireflection film is formed after forming the semiconductor device upper structure. Usually, as shown in FIG.
The upper structure of the semiconductor device has the following configuration. (A) First interlayer insulating film 32 made of SiO ₂ layer formed on silicon substrate 30 by atmospheric pressure CVD (B) First aluminum wiring layer 34 (C) Second formed by plasma CVD SiO
₂ layers, silicon nitride film formed by plasma CVD,
Alternatively, a second interlayer insulating film 36 composed of two layers of a silicon nitride film layer / a SiO ₂ layer formed by plasma CVD (D) a second aluminum wiring layer 38, and (E) formed by plasma CVD Overcoat layer 40 made of a silicon nitride film

In the first conventional method, the above-mentioned semiconductor device upper structure formed on the light receiving portion of the photodiode portion is subjected to reactive ion etching (RI).
After removal by E) or the like, an antireflection film 42 is formed (see FIG. 4). The antireflection film is, for example, a silicon nitride film single layer formed by plasma CVD, a SiO ₂ film single layer formed by plasma CVD, or a silicon nitride film / SiO ₂ film formed respectively by plasma CVD. Composed of layers.

Alternatively, in the second conventional method,
As the antireflection film, the above-described semiconductor device upper structure (see FIG. 3) is used as it is. In this case, the first interlayer insulating film 32, the second interlayer insulating film 36 made of SiO ₂ layer or the like, and the anti-reflection film overcoat layer 40 made of a silicon nitride film made of SiO ₂ layer is structured.

[0007]

In the first conventional method of forming the antireflection film after forming the upper structure of the semiconductor device, an additional step of forming the antireflection film is required, and the manufacturing process of the semiconductor device is performed. And an increase in manufacturing cost.

In the second conventional method in which the upper structure of the semiconductor device is used as it is as an antireflection film, the antireflection film is composed of two or more kinds of thin films. Therefore, when the film thickness of each thin film changes, the reflectance of the antireflection film also changes. Compared with the case where the antireflection film has a single-layer structure, in the case of a multilayer structure, there is a problem that the fluctuation of the reflectance becomes large because the fluctuations of the film thickness of each thin film are accumulated.

Therefore, an object of the present invention is to use the conventional MIS capacitor portion forming process to form an antireflection film having a small fluctuation in reflectance without increasing the manufacturing process of a semiconductor device. It is to provide a semiconductor device having a diode portion and a method for manufacturing the same.

[0010]

In order to achieve the above object, the semiconductor device of the present invention is characterized in that an antireflection film is provided on the light receiving portion of the photodiode portion, and the antireflection film is made of a silicon nitride film. And The photodiode part is p
It has an n-junction or a pin-junction.

The antireflection film is composed of a silicon nitride film for forming the MIS capacitance portion, an interlayer insulating film made of a silicon nitride film, and an overcoat layer made of a silicon nitride film.

The semiconductor device having a photodiode of the present invention comprises: (a) a step of forming a SiO ₂ layer on a silicon substrate and then selectively etching the SiO ₂ layer on the light receiving portion of the photodiode; ) A step of depositing a silicon nitride film on the SiO ₂ layer and the light receiving part, and then selectively etching the silicon nitride film to form a MIS capacitor part, and (c) a step of forming a first wiring layer And (d) depositing a silicon nitride film as an interlayer insulating film,
(E) a step of forming a second wiring layer, and (f) a step of depositing a silicon nitride film to form an overcoat layer,
It can be manufactured by a manufacturing method comprising.

[0013]

In the semiconductor device of the present invention, the conventional MIS
A capacity part forming process is used. Therefore, even though the antireflection film is made of a silicon nitride film, unlike the conventional first method, an additional step of forming the antireflection film is unnecessary, and the manufacturing cost of the semiconductor device can be reduced. You can
Moreover, since the antireflection film is composed of one kind of material, that is, the silicon nitride film, the antireflection film suppresses the fluctuation of the reflectance of the antireflection film as compared with the conventional second method having a multilayer structure. You can

[0014]

EXAMPLE A process of forming an antireflection film will be described below with reference to FIGS. The method for manufacturing a semiconductor device having a photodiode section according to the present invention utilizes a conventional MIS capacitor section forming step.

SiO is formed on the silicon substrate 1 by atmospheric pressure CVD.
_{The two} layers 10 are formed, and emitter diffusion annealing for activating arsenic in the emitter portion is performed. Next, in order to form the MIS capacitor portion, the SiO ₂ layer 10 is formed by low pressure CVD.
Are selectively etched to form openings 12 (see FIG. 1).
(See (A)). This opening serves as a light receiving portion of the photodiode portion.

After that, the SiO ₂ layer 10 and the opening 12 are formed.
Then, a silicon nitride film 14 is formed by low pressure CVD, and then unnecessary silicon nitride film is removed by etching (see FIG. 1B). As a result, the MIS capacitor section is formed. Then, in order to improve the condition of the surface of the silicon substrate, heat treatment is performed using N ₂ . This heat treatment
It is unnecessary in some cases.

Next, wiring is formed for each element portion of the semiconductor device. That is, a first contact hole portion is formed in the SiO ₂ layer, a polysilicon layer is formed by CVD, and then a first metal layer made of, for example, aluminum is formed by an evaporation method.
The SiO ₂ layer is deposited on the opening and the first contact hole. After that, the polysilicon layer and the first metal layer other than the portion used as the wiring are patterned and removed by etching to form the first wiring layer. Then, by performing a sintering process, the silicon substrate and the first wiring layer are made to conform to each other to form a good contact. Note that FIG. 1 shows only the photodiode portion, and does not show the first contact hole portion and the first wiring layer.

After that, a silicon nitride film is deposited in the opening by plasma CVD, the silicon nitride film is smoothed by RIE, and a silicon nitride film is further deposited by plasma CVD to form an interlayer insulating film 1 of the silicon nitride film.
6 is formed on the entire surface (see FIG. 1C). Next, after ion implantation of argon, a second contact hole portion is formed in the interlayer insulating film made of a silicon nitride film.

Then a second, for example made of aluminum
Is deposited on the interlayer insulating film and on the second contact hole portion, and the second metal layer is patterned and etched to remove unnecessary portions to form the second wiring layer 18 (see FIG. 1). (D)). The first wiring layer and the second wiring layer are connected by the second contact hole. The second wiring layer 18 also has a function of shielding the semiconductor device other than the portion where the photodiode portion is formed from light.

Then, by performing a sintering process, the first wiring layer and the second wiring layer are made to conform to each other to form a good contact. Then, in order to protect the surface of the semiconductor device and enhance reliability, a silicon nitride film is formed by plasma CVD to form the overcoat layer 20 (see FIG. 2).

[0021]

In the semiconductor device of the present invention, an additional step of forming an antireflection film is unnecessary, and the manufacturing cost of the semiconductor device can be reduced. Moreover, since the antireflection film is made of one kind of material, that is, the silicon nitride film, it is possible to suppress the fluctuation of the reflectance of the antireflection film as compared with the case where the antireflection film has a multilayer structure.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a semiconductor device showing a method for manufacturing a semiconductor device having a photodiode section according to the present invention.

FIG. 2 is a sectional view of a photodiode portion of a semiconductor device of the present invention.

FIG. 3 is a cross-sectional view showing an upper structure of a semiconductor device having a conventional photodiode section.

FIG. 4 is a sectional view showing an antireflection film of a conventional semiconductor device having a photodiode section.

[Explanation of symbols]

1 Silicon Substrate 10 SiO ₂ Layer 12 Opening 14 Silicon Nitride Film 16 Interlayer Insulating Film 18 Second Wiring Layer 20 Overcoat Layer

Claims (3)

[Claims] 1. A semiconductor device having a photodiode portion, wherein an antireflection film is provided on a light receiving portion of the photodiode portion, and the antireflection film is made of a silicon nitride film. 2. The antireflection film is a silicon nitride film for forming a MIS capacitor portion, an interlayer insulating film made of a silicon nitride film,
The semiconductor device according to claim 1, wherein the semiconductor device comprises an overcoat layer made of a silicon nitride film. 3. A method of manufacturing a semiconductor device having a photodiode, comprising: (a) forming a SiO ₂ layer on a silicon substrate and then selectively etching the SiO ₂ layer on a light receiving portion of the photodiode. And (b) depositing a silicon nitride film on the SiO ₂ layer and the light receiving portion, and then selectively etching the silicon nitride film,
A step of forming a MIS capacitor portion, (c) a step of forming a first wiring layer, (d) a step of depositing a silicon nitride film as an insulating film between wiring layers, and (e) a second wiring layer A method of manufacturing a semiconductor device, comprising the steps of: (f) depositing a silicon nitride film to form an overcoat layer.