JPH05114609A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor device having high reliability by incorporating the step of laminating a polysilicon layer on a semiconductor substrate and then ion implanting a source/drain region through the layer and the step of oxidizing the layer in an oxidative atmosphere. CONSTITUTION:An active region and an element isolating region 2 made of a field oxide film are formed on a silicon substrate 1. After a gate electrode 3 is formed on the region 2 through a gate oxide film 9 made of SiO2, As is implanted to form a source/drain region 5 in which a low concentration impurity is diffused. Further, a sidewall 4 made of SiO2 is formed on the electrode 3. Then, a polysilicon layer 6 is formed on the substrate 1. Thereafter, with the electrode 3 as a mask As is implanted through the layer 6 to form a high concentration impurity diffused region 5b on the low concentration impurity diffused region 5a. Thereafter, it is heat treated in an oxidative atmosphere.

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 semiconductor device, and more particularly to a method for manufacturing a MOS type semiconductor device.

[0002]

2. Description of the Related Art When manufacturing a conventional MOS transistor, a semiconductor substrate is first formed with an element isolation region including an active region and a field oxide film, and further with a gate electrode formed in the active region via a gate oxide film. Then, n ⁻ ions are implanted to form source / drain regions. Next, after forming a sidewall made of SiO _{2 on the} gate electrode, n ⁺ ions are implanted again into the source / drain regions to form the source / drain regions having the LDD structure.

[0003]

With the speeding up and miniaturization of devices such as MOS transistors, it is essential to form a source / drain with a shallow junction depth. In the method of manufacturing a semiconductor device described above, However, there are problems that the semiconductor substrate is damaged by ion implantation, and that the heat treatment promotes the diffusion of impurities into the semiconductor substrate. Therefore, there is a problem that a leak current occurs at the junction and it is difficult to form a shallow p / n junction having good junction characteristics.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device having excellent junction characteristics and capable of forming a shallow p / n junction.

[0005]

According to the present invention, in order to solve the above-mentioned problems, according to the present invention, a polysilicon film is formed on a semiconductor substrate on which a gate electrode having a sidewall is arranged and a source / drain region is formed. The method is characterized by including a step of implanting ions into the source / drain regions through the polysilicon layer after stacking the silicon layer, and a step of oxidizing the polysilicon layer in an oxidizing atmosphere.

In the present invention, the polysilicon layer is 20 to
It is preferably formed with a thickness of 60 nm. Further, in the semiconductor substrate in which the source / drain regions used in the present invention are formed, B or the like is 40 when the source / drain regions are P-type impurity diffusion regions, and As, P or the like is 40 when the source / drain regions are N-type impurity diffusion regions. ~80KeV, 1~3 × 10 ¹² cm ^-2 order is preferably one that is implanted at a concentration of, in the step of performing ion implantation into the source / drain regions through the polysilicon layer, the source / drain regions of the P-type impurity diffusion regions In the case of forming in the N type impurity diffusion region, As and P in the case of forming in the N type impurity diffusion region 40 to 80 KeV, 1 to 3 × 10 ¹⁵ c
It is preferable to inject at a concentration of about m ⁻² .

The gate oxide film, the side wall, etc., and the gate electrode and the polysilicon layer in the present invention can be formed by a known method such as a CVD method.
In the step of oxidizing the polysilicon layer in an oxidizing atmosphere, heat treatment after ion implantation can be performed at the same time. In this case, 30 in the temperature range of 900 to 1000 ° C.
It is preferable to carry out for about 1 minute to 1 hour. Furthermore, the polysilicon layer after this step is entirely oxidized and can be handled as an oxide film in a later step.

[0008]

According to the method of manufacturing a semiconductor device described above, a polysilicon layer is laminated on a semiconductor substrate on which a gate electrode having a sidewall is formed and a source / drain region is formed, and then the polysilicon layer is deposited. Since the step of implanting ions into the source / drain regions through the silicon layer and the step of oxidizing the polysilicon layer in an oxidizing atmosphere are included, first, the ion implantation is performed on the polysilicon layer stacked on the semiconductor substrate. Be seen. This avoids damage caused by ion implantation and forms the source / drain regions in which desired impurities are diffused by solid phase diffusion from the polysilicon layer in the semiconductor substrate.

Further, since the polysilicon layer is entirely oxidized, it is handled as an oxide film without removing the polysilicon layer in a later step. Therefore, a shallow p-shaped semiconductor substrate with less damage and good junction characteristics is provided.
A / n junction will be formed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described with reference to the drawings. First, an element isolation region (2) made of an active region and a field oxide film is formed on a silicon substrate (1) as a semiconductor substrate. Then, after forming the gate electrode (3) in the element formation region via the gate oxide film (9) made of SiO ₂ , As is 80 Ke, for example.
The source / drain region (5) is formed by implanting V at a concentration of about 1 × 10 ¹² cm ^{−2 and} diffusing low concentration impurities.
Further, a sidewall (4) made of SiO ₂ is formed on the gate electrode (3) (FIG. 1 (a)).

Then, about 20n is formed on the silicon substrate (1).
After forming a polysilicon layer (6) by stacking polysilicon having a thickness of m, As is 80 KeV through the polysilicon layer (6) using the gate electrode (3) as a mask,
The source / drain region (5) is formed by implanting at a concentration of about 1 × 10 ¹⁵ cm ⁻² and forming the high concentration impurity diffusion region (5b) on the low concentration impurity diffusion region (5a) ( FIG. 1B).

After that, in an oxidizing atmosphere, at 900 ° C. for 30 minutes.
Heat treatment is performed for a minute to diffuse the impurities into the source / drain regions (5) and oxidize the entire polysilicon layer (6) to form a SiO ₂ film (7) (FIG.
(C)). In this embodiment, the case where the NMOS is manufactured is described, but the PMOS or the CMOS is used.
Can be similarly performed.

[0013]

According to the method of manufacturing a semiconductor device of the present invention, a polysilicon layer is laminated on a semiconductor substrate having a gate electrode having a sidewall formed therein and having source / drain regions formed therein. After that, since a step of implanting ions into the source / drain regions through the polysilicon layer and a step of oxidizing the polysilicon layer in an oxidizing atmosphere are included, first, ions are implanted in the polysilicon layer stacked on the semiconductor substrate. The injection is done. This makes it possible to avoid damage caused by ion implantation in the semiconductor substrate, and form source / drain regions in which desired impurities are diffused by solid phase diffusion from the polysilicon layer.

Therefore, it is possible to form a shallow p / n junction with a small amount of damage and good junction characteristics in a semiconductor substrate without complicated manufacturing steps, and prevent leakage current at the junction to be reliable. It becomes possible to manufacture a semiconductor device having high property.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a method for manufacturing a semiconductor device according to the present invention.

[Explanation of symbols]

 1 Silicon Substrate (Semiconductor Substrate) 3 Gate Electrode 4 Sidewall 5 Source / Drain Region 6 Polysilicon Layer 9 Gate Oxide Film

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01L 27/092 7342-4M H01L 27/08 321 E

Claims (1)

[Claims] 1. A polysilicon layer is stacked on a semiconductor substrate on which a gate electrode having a sidewall is formed and a source / drain region is formed, and then an ion is deposited on the source / drain region through the polysilicon layer. A method of manufacturing a semiconductor device, comprising: a step of implanting and a step of oxidizing a polysilicon layer in an oxidizing atmosphere.