JPH0766409A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the substratum attack due to HF punching in the case of HF treatment, the withstand voltage deterioration, the contamination penetration of Si based material from the outside, the deterioration of quality, and the influence upon the substratum at the time of etching a gate insulating film in a process, when electrode structure is formed by using the Si based material. CONSTITUTION:Electrode structure 1 composed of Si based conductive material is formed and provided with at least a nitrogen containing Si based conductive material layer 2 which is composed of N-doped Si. In the manufacturing method of a semiconductor device provided with electrode structure composed of Si based conductive material, at least one time deposition process for forming an Si based material film, and at least one time deposition process for forming a nitrogen containing Si based material Film are performed in an arbitrary order. Thereby a semiconductor device is manufactured wherein electrode structure provided with at least one nitrogen containing Si based conductive material layer is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and its manufacturing method. The present invention particularly relates to a semiconductor device having an electrode structure made of a silicon-based conductive material, and a manufacturing method thereof. INDUSTRIAL APPLICABILITY The present invention can be preferably used for a semiconductor device having a structure of electrode-insulator-semiconductor material, which is called MOS or MIS, for example. In this specification, MOS or MIS is used in a broad sense and generally refers to a semiconductor device having an electrode structure on a semiconductor material with an insulator interposed therebetween.

[0002]

2. Description of the Related Art A typical structure of a semiconductor device having an electrode structure made of a silicon-based conductive material is a silicon-based material such as polysilicon on a gate insulating film (SiO ₂ or SiN) on a semiconductor substrate. LP-CVD (low pressure C
It is formed by the VD method and is provided with an electrode structure in which impurities (phosphorus) are introduced into the polysilicon by ion implantation or phosphorus diffusion from a phosphorus-containing material such as PSG.

The conventional semiconductor device as described above has some problems.

One is a process problem. In the processing after forming the polysilicon, HF treatment is performed several times. At this time, HF penetrates the polysilicon and attacks the underlying gate insulating film. And this
The pressure resistance may be deteriorated.

As a countermeasure for the above problem, a PH
In-situ Doped, in which impurities (phosphorus) are introduced at the same time as film formation using a gas with ₃ added
Poly-Si and Phos. Doped Amor
Although a technique for forming dense-Si has been proposed, it is not yet sufficient.

Another problem is a structural problem, and the polysilicon electrode has a possibility that external contamination may pass through the polysilicon electrode and affect the semiconductor device. This problem is that, even in the process, when the gate insulating film is processed by etching, contamination through polysilicon (for example, alkali metal such as Na or heavy metal such as Fe) may affect the base. Leads to problems. A gate insulating film, an oxide film - nitride - oxide film, for example, SiO ₂ -S
This problem can be suppressed by adopting the MONOS structure having the iN-SiO ₂ structure, but the MONOS structure has a complicated forming process.

[0007]

It is an object of the present invention to solve the above-mentioned problems of the prior art, and when an electrode structure is formed of a silicon-based material such as polysilicon, when HF treatment or the like is performed in processing after formation. Also prevents the attack of the base due to the penetration of HF, thus preventing the deterioration of the pressure resistance, and also prevents the passage of the contamination from the outside of the silicon-based material such as polysilicon, and thus the performance deterioration and the gate in the process. An object of the present invention is to provide a semiconductor device capable of preventing an influence on a base due to contamination passing when an insulating film is processed by etching, and a semiconductor device manufacturing method capable of realizing the same with a simple structure.

[0008]

According to a first aspect of the present invention, in a semiconductor device having an electrode structure made of a silicon-based conductive material, the electrode structure includes at least one nitrogen-containing silicon-based conductive material layer. A semiconductor device characterized by having the above-mentioned object.

According to a second aspect of the present application, in a method of manufacturing a semiconductor device having an electrode structure made of a silicon-based conductive material, at least one deposition step for film-forming a silicon-based material and at least one nitrogen step. A method for manufacturing a semiconductor device, characterized in that an electrode structure having at least one nitrogen-containing silicon-based conductive material layer is formed by performing a deposition step for forming a content-containing silicon-based material layer in an arbitrary order. Therefore, the above object is achieved thereby.

[0010]

In the semiconductor device of the present invention, since the electrode structure made of the silicon-based conductive material has at least one nitrogen-containing silicon-based conductive material layer, this nitrogen-containing silicon-based conductive material layer serves as a stopper. As a result, the passage of contamination from the outside is blocked, and the adverse effect on the semiconductor device is prevented. In addition, the nitrogen-containing silicon-based conductive material layer also serves as a stopper for the processing liquid (HF or the like) even in the manufacturing process, and prevents the processing liquid from adversely affecting the base. It also serves as a stopper against the passage of contaminants when the gate insulating film is processed by etching, and prevents the influence of contamination on the base.

In the method for manufacturing a semiconductor device of the present invention, at least one deposition step for forming a silicon-based conductive material film and at least one deposition step for forming a nitrogen-containing silicon-based conductive material layer are optional. By carrying out in this order, an electrode structure having at least one nitrogen-containing silicon-based conductive material layer is formed. Therefore, a semiconductor device having the above effect can be easily obtained with a simple structure. In addition, in the manufacturing method of the semiconductor device of the present invention, the nitrogen-containing silicon-based conductive material layer serves as a stopper for the processing liquid (HF, etc.) in the manufacturing process to prevent the processing liquid from adversely affecting the base. This also serves as a stopper against the passage of contamination when the gate insulating film is processed by etching, etc., and exhibits the effect of preventing the influence of contamination on the underlying layer.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Of course, the present invention is not limited to the embodiments.

Example 1 In this example, the present invention is applied to a semiconductor device having a polysilicon gate electrode structure and its manufacture. In the present embodiment, the present invention is embodied in the MOS transistor portion of the CCD constituting the image pickup device.
As for the CCD constituting the image pickup device, improvement of acid resistance (prevention of punch-through) in the thin film polysilicon gate structure, prevention of damage that affects MOS characteristics, and prevention of contamination (contamination) are desired. The present invention can be preferably used.

Referring to FIG. As shown in FIG. 1, the semiconductor device of this embodiment is a semiconductor device including an electrode structure 1 made of a silicon-based conductive material.
Is at least one nitrogen-containing silicon-based conductive material layer 2
have.

More specifically, the electrode structure 1 of this embodiment is
On the gate insulating film 4 (SiO _{2 in} this embodiment) formed on the silicon substrate which is the semiconductor substrate 3, the polysilicon (or the amorphous silicon) which is the silicon-based material layer 1a in order from the lower side (from the substrate 3 side). Layer, N-doped polysilicon (or amorphous silicon) layer that is the nitrogen-containing silicon-based material layer 2, and silicon-based material layer 1b
Is polysilicon (or amorphous silicon)
It has a three-layer structure composed of layers. The nitrogen-containing silicon-based material layer 2 is sandwiched between two silicon-based material layers 1a and 1b.

The semiconductor device of this embodiment is manufactured by the process shown in FIG. That is, in manufacturing a semiconductor device having the electrode structure 1 made of a silicon-based conductive material, at least one deposition step Ia, I for depositing a silicon-based conductive material is performed.
b and the deposition step II for forming the nitrogen-containing silicon-based conductive material layer at least once in any order,
An electrode structure (see FIG. 1) having at least one nitrogen-containing silicon-based conductive material layer 2 is formed.

In this embodiment, the deposition process is LP-CVD.
Insi performed by the (low-pressure CVD) method and at the same time when the silicon-based material is formed by introducing impurities for imparting conductivity.
The tu method was adopted. More specifically, as shown in FIG. 2, a silicon substrate wafer (a semiconductor substrate having a necessary impurity diffusion layer formed on which a gate oxide film is formed), which is a semiconductor substrate to be processed, is loaded into a CVD apparatus (see FIG. II of 2
I), the chamber of the CVD apparatus is evacuated IV to a predetermined pressure atmosphere. Then, a silicon material was deposited.

In the present embodiment, first, the gas system introduced as the source gas is SiH ₄ gas introduction ON and PH ₃ gas introduction ON, whereby SiH ₄ gas and PH are introduced.
₃ Gas is used to form a polysilicon (or amorphous silicon) layer in which phosphorus is introduced as an impurity.
This is the first deposition step Ia for depositing a silicon-based conductive material in this example.

Next, in this embodiment, SiH ₄ gas introduction is turned on and NH ₃ gas introduction is turned on, whereby SiH ₄ gas and NH ₃ gas are used to form a polysilicon (or amorphous silicon) layer containing nitrogen. Form. This is the deposition step II for forming the nitrogen-containing silicon-based conductive material layer in this embodiment. The deposition step II for forming the nitrogen-containing silicon-based conductive material layer should be performed continuously with the first deposition step Ia for forming the silicon-based conductive material film and adding NH ₃ gas thereto. You can

In this embodiment, next, deposition for film formation of a silicon-based conductive material is performed again. That is, the gas system to be introduced as the source gas is SiH ₄ gas introduction ON and PH
₃ , gas introduction is turned on, and thereby a SiH ₄ gas and a PH ₃ gas are used to form a polysilicon (or amorphous silicon) layer in which phosphorus is introduced as an impurity. That is, the second deposition step Ib for depositing a silicon-based conductive material in this example is performed.

Evacuate, purge with nitrogen (VII),
Leak VIII is performed and the wafer is unloaded X. With this, the CVD is completed, and thereafter, pattern formation is carried out by a photoresist method, and a silicon-based conductive material layer / nitrogen-containing silicon-based conductive material layer /
Formed by etching a three-layer gate structure of a polysilicon (or amorphous silicon) layer / a nitrogen-containing polysilicon (or amorphous silicon) layer / a polysilicon (or amorphous silicon) layer, which is a structure of a silicon-based conductive material layer. To do. After that, the interlayer insulating film 5
To form.

According to this embodiment, after the gate electrode is formed,
Even when the surface is subjected to HF treatment, the HF is blocked by the nitrogen-containing silicon-based material layer 2 and penetrates the polysilicon gate film that is the electrode structure 1 made of a silicon-based conductive material to attack the underlying gate insulating film. Is prevented. This makes it possible to suppress the phenomenon that the MOS breakdown voltage is deteriorated.

Particularly in the case of the semiconductor device used for the CCD light receiving element as in this embodiment, since it is desired to form a thin polysilicon gate film of 100 nm or less, the above operation is extremely useful in this case.

Further, according to the present embodiment, even when the gate insulating film is processed by etching, the contamination (eg, the alkali metal such as Na or the heavy metal such as Fe) through the polysilicon is blocked, and the contamination underlying layer is formed. The effect of can be prevented.

Even in the semiconductor device device structure, it was possible to prevent the contamination from the outside from passing through the silicon-based electrode structure and affecting the semiconductor device device.

This embodiment has the same advantages as when the gate insulating film has an MONOS structure in which an oxide film-nitride film-oxide film, for example, a SiO ₂ -SiN-SiO ₂ structure is used.
It can be said that the MOS structure has a simple structure.

In the present embodiment, in forming a silicon-based gate electrode, in the LP-CVD process, a certain amount of NH ₃ gas is added to SiH ₄ gas during the film formation, so that polysilicon containing several% of nitrogen ( Or amorphous silicon) or SixNy (silicon nitride) is formed and sandwiched by polysilicon (or amorphous silicon), the resulting MOS gate has H
F resistance can be improved, deterioration of MOS breakdown voltage can be suppressed, metal impurities during etching can be blocked, interface characteristics and Si bulk MOS characteristics can be improved, and dark current can be favorably maintained.

In the present embodiment, the in situ method is adopted in which the impurity for imparting conductivity to the silicon material is introduced simultaneously with the introduction of the impurity for imparting conductivity to the silicon material (polysilicon) film formation. Other than that, phosphorus is ion-implanted into silicon-based materials (polysilicon, amorphous silicon, etc.). PSG (phosphorus-containing silicon glass) in the silicon-based material (polysilicon, amorphous silicon, etc.) layer
After forming a film, it is thermally diffused. A silicon-based material (polysilicon, amorphous silicon, or the like) containing phosphorus-containing gas (for example, POCl ₃
Spread the vapor and introduce phosphorus. Means such as can also be used arbitrarily. (The same is true for the other examples).

Example 2 In this example, the electrode structure has a lower layer (gate insulating film side) of a polysilicon (or amorphous silicon) layer and an upper layer of a nitrogen-containing polysilicon (or amorphous silicon) layer. . The means for forming each layer is
Same as Example 1. This embodiment also brings about the same effect as that of the first embodiment.

Embodiment 3 In this embodiment, the electrode structure has a lower layer (gate insulating film side) of a nitrogen-containing polysilicon (or amorphous silicon) layer and an upper layer of polysilicon (or an amorphous silicon layer). The means for forming each layer is
Same as Example 1. This embodiment also brings about the same effect as that of the first embodiment.

Example 4 In this example, nitrogen was introduced into a silicon material (polysilicon or amorphous silicon) by ion implantation. Others were the same as in Example 1. This embodiment also brings about the same effect as that of the first embodiment.

[0032]

According to the present invention, when an electrode structure is formed of a silicon-based material such as polysilicon, even when an HF treatment is performed during processing after the formation, the underlayer is attacked due to HF penetration. Therefore, it is possible to prevent the deterioration of pressure resistance, and also to prevent the passage of contamination from the outside of silicon-based materials such as polysilicon, performance deterioration and when processing the gate insulating film in the process by etching, etc. It is possible to provide a semiconductor device capable of preventing the influence on the base due to the passage of contaminants, and a method of manufacturing the semiconductor device capable of realizing this with a simple configuration.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor device according to a first embodiment.

FIG. 2 is a flow chart showing a manufacturing process of the semiconductor device of the first embodiment.

[Explanation of symbols]

1 Silicon Electrode Material 1a, 1b Silicon Material Layer (Polysilicon or Amorphous Silicon) Layer 2 Nitrogen-Containing Silicon Material (Polysilicon Containing Nitrogen or Amorphous Silicon) Layer 3 Semiconductor Substrate 4 Gate Insulating Film

Claims (2)

[Claims] 1. A semiconductor device having an electrode structure made of a silicon-based conductive material, wherein the electrode structure has at least one nitrogen-containing silicon-based conductive material layer. 2. A method of manufacturing a semiconductor device having an electrode structure made of a silicon-based conductive material, comprising: a deposition step for forming a silicon-based material film at least once;
By performing at least one deposition step for forming the nitrogen-containing silicon-based material layer in any order, at least 1
A method of manufacturing a semiconductor device, comprising forming an electrode structure having a nitrogen-containing silicon-based conductive material layer.