JPH11145425A - Manufacture of semiconductor element and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control diffusion of impurities into a diffusion layer by a method, wherein a silicon nitride film is deposited on a storage node electrode, a silicon film is deposited thereon, and they are oxidized. SOLUTION: After a field oxide film 102, a gate oxide film 103, a gate electrode 104 and N-types diffused layers 105 and 106 have been formed on a P-type silicon substrate 101, an interlayer insulating film 107 and bit line 108 are formed thereon. After the deposition of a silicon film by an LPCD method, a storage node electrode 109 is formed by performing dry etching using a photoresist film as a mask. Then, a silicon nitride film 110 is deposited using an LPCD method, and an amorphous silicon film 111 is deposited at the temperature of 500 to 550 deg.C through the LPCD method. A rapid thermal oxidation operation is conducted on the amorphous silicon film 111 for 20 to 40 seconds in the oxidation atmosphere of 800 to 1,000 deg.C, and a silicon oxide film 111 is formed. The time for the heat treatment can be made short and the heat treatment can be performed at a low temperature using amorphous silicon, etc., and the diffusion of impurities on a diffusion layer can be controlled.

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 element and a technique of a semiconductor device, and more particularly to a technique of manufacturing a capacitor insulating film of a semiconductor element having a capacitor.

[0001]

2. Description of the Related Art Conventionally, a silicon oxide film / silicon nitride film structure is used as a capacitive insulating film. This is because the leakage current can be suppressed by forming an oxide film on the surface of the nitride film. This is described as a reference in “Semiconductor Research@P.17”.

A method of manufacturing a capacitive element will be described with reference to FIGS.

[0003] First, a field oxide film 202 is formed in a device isolation region on the surface of a P-type silicon substrate 201.
A gate oxide film 203 is formed. After forming the gate electrode 204 also serving as a gate line, N-type diffusion layers 205 and 206 serving as source / drain regions are formed by ion implantation or the like.

Next, after depositing an interlayer insulating film 207 made of a silicon oxide based insulating film by a CVD (chemical vapor deposition) method, a bit line 208 is formed. Further, after depositing the interlayer insulating film 207, a contact hole is opened.

Next, after depositing a silicon film by LPCVD (Low Pressure Chemical Vapor Deposition), dry etching is performed using a photoresist film (not shown) as a mask to form a storage node electrode 209 (FIG. 6). ). Next, as shown in FIG. 7, a silicon nitride film 2 having a thickness of about 6 to 7 nm is formed.
10 is deposited by the LPCVD method.

Next, as shown in FIG. 8, the surface of the silicon nitride film is oxidized using a diffusion furnace,
Form one. The oxidation conditions at this time are 800-900 ° C.
And the thickness of the formed silicon oxide film 211 is 1 to 1.5 nm. Further, as shown in FIG. 9, the cell plate electrode 212 is formed, and the formation of the capacitor is completed.

[0007]

When oxidizing a nitride film as in the past, it is necessary to perform a heat treatment at a high temperature (800 to 900 ° C. or higher) for a long time (15 to 60 minutes). There is a problem that redistribution occurs, element isolation characteristics deteriorate, and yield decreases.

Therefore, an object of the present invention is to suppress the diffusion of impurities in a diffusion layer and to form a capacitive insulating film having a silicon oxide film / silicon nitride film structure.

[0009]

According to the present invention, there is provided a method for forming a capacitive insulating film of a semiconductor device, comprising the steps of: depositing a silicon nitride film on a storage node electrode; A method including a step of depositing a silicon film on the film and a step of oxidizing the silicon film was employed. . Here, the thickness of the silicon film may be 1 to 1.5 nm. Further, the silicon film is preferably an amorphous silicon film. The silicon film is made of silane (SiH4) or disilane (Si2H6) at a temperature of 500 to 550C.
It can also be crushed using. The step of oxidizing the silicon film can be performed by a rapid thermal oxidation method in an oxidizing atmosphere at a temperature of 800 to 1000 ° C. The step of oxidizing the silicon film is performed in an oxidizing atmosphere of 700 to 80.
It can also be carried out by pyrogenetic oxidation at about 0 ° C. The thickness of the silicon nitride film may be 6 to 7 nm. On the other hand, according to the present invention, in a semiconductor device having a capacitor insulating film on a capacitor lower electrode, the capacitor insulating film is formed by forming a silicon nitride film, an amorphous silicon film on the silicon nitride film, and oxidizing the amorphous silicon film. The structure was made to be. In that case, the thickness of the amorphous silicon film may be 1 to 1.5 nm.

The capacitor insulating film of the present invention is formed by depositing a silicon nitride film on a capacitor lower electrode, depositing amorphous silicon on the order of 1 to 1.5 nm, and then oxidizing amorphous silicon. Oxidation of amorphous silicon makes it possible to shorten the time required for heat treatment or to lower the temperature, thereby suppressing the spread of the diffusion layer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

First, a field oxide film 102 is formed in a device isolation region on a surface of a P-type silicon substrate 101,
A gate oxide film 103 is formed. After forming the gate electrode 104 also serving as a gate line, N-type diffusion layers 105 and 106 serving as source / drain regions are formed by ion implantation or the like.

Next, after depositing an interlayer insulating film 107 made of a silicon oxide-based insulating film by a CVD (chemical vapor deposition) method, a bit line 108 is formed. Further, after depositing the interlayer insulating film 207, a contact hole is opened.

Next, after depositing a silicon film by LPCD (Low Pressure Chemical Vapor Deposition) method, dry etching is performed using a photoresist film (not shown) as a mask to form a storage node electrode 109 (FIG. 1). ).

Next, as shown in FIG.
A silicon nitride film 110 is deposited by the LPCVD method. Up to this point, it is the same as the conventional method shown in FIGS.

Next, as shown in FIG.
At 50 ° C., the film thickness is 1 to 1.5 n by the LPCVD method.
An amorphous silicon film 111 of about m is deposited. At this time, the amorphous silicon film is used because it is superior to polysilicon in terms of controllability in depositing a thin film (1 to 1.5 nm).

Next, as shown in FIG. 4, the amorphous silicon film 111 is subjected to rapid thermal oxidation in an oxidizing atmosphere at 800 to 1000 ° C. for 20 to 40 seconds to form a silicon oxide film 111.

Further, as shown in FIG. 5, a cell plate electrode 113 is formed, and the formation of the capacitor is completed.

In the above description, the oxidation is performed by the rapid oxidation method. However, the oxidation can be performed by using a diffusion furnace. In this case, after depositing amorphous silicon, oxidation is performed in an oxidizing atmosphere at a temperature of about 700 to 800 ° C. for 10 to 15 minutes.

[0020]

According to the present invention, when forming a capacitor insulating film having an oxide film / nitride film structure, conventionally, a temperature of 800 to 900.degree.
However, redistribution of impurities in the diffusion layer occurs due to the need for a long heat treatment at a high temperature for a short time. In addition, it is possible to minimize the spread of the diffusion layer, thereby obtaining an effect of improving the yield.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a manufacturing process according to the embodiment of the present invention.

FIG. 3 is a schematic sectional view of a manufacturing process according to the embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a manufacturing process according to the embodiment of the present invention.

FIG. 5 is a schematic sectional view of a manufacturing process according to the embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a manufacturing process of a conventional capacitive element.

FIG. 7 is a schematic cross-sectional view of a manufacturing process of a conventional capacitive element.

FIG. 8 is a schematic cross-sectional view of a manufacturing process of a conventional capacitive element.

FIG. 9 is a schematic cross-sectional view of a manufacturing process of a conventional capacitive element.

[Explanation of symbols]

 101, 201 P-type silicon substrate 102, 202 Field oxide film 103, 203 Gate oxide film 104, 204 Gate electrode 105, 106, 205, 206 N-type diffusion layer 107, 207 Interlayer insulating film 108, 208 Bit line 109, 209 -Node electrode 110, 210 Silicon nitride film 111 Amorphous silicon film 112, 211 Silicon oxide film 113, 212 Cell plate electrode

Claims (9)

[Claims] 1. A method for forming a capacitive insulating film of a semiconductor device, comprising the steps of: depositing a silicon nitride film on a storage node electrode; depositing a silicon film on the silicon nitride film; Oxidizing the semiconductor device. 2. The method according to claim 1, wherein the silicon film has a thickness of 1 to 1.5 n.
2. The method according to claim 1, wherein m is m. 3. The method according to claim 1, wherein the silicon film is an amorphous silicon film. 4. The method according to claim 1, wherein the silicon film has a temperature of 500 to 550.
Silane (SiH4) or disilane (Si2
The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is crushed using H6). 5. The semiconductor device according to claim 1, wherein the step of oxidizing the silicon film is performed by a rapid thermal oxidation method in an oxidizing atmosphere at a temperature of 800 to 1000 ° C. Manufacturing method. 6. The method according to claim 1, wherein the step of oxidizing the silicon film is performed by pyrogenetic oxidation at about 700 to 800 ° C. in an oxidizing atmosphere.
5. The method for manufacturing a semiconductor device according to any one of 4. 7. The silicon nitride film has a thickness of 6 to 7 n.
2. The method according to claim 1, wherein m is m. 8. A semiconductor device having a capacitor insulating film on a capacitor lower electrode, wherein the capacitor insulating film is formed by forming a silicon nitride film, an amorphous silicon film on the silicon nitride film, and forming the amorphous silicon film on the silicon nitride film. A semiconductor device having an oxidized structure. 9. The amorphous silicon film having a thickness of 1
9. The semiconductor device according to claim 8, wherein the thickness is from 1.5 nm to 1.5 nm.