JP2716300B2 - Method for manufacturing semiconductor device - Google Patents

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 Conventional LDD (Lightly Doped Drain) structure
A method for manufacturing a MOS memory cell having a structure is described with reference to FIG.
Will be described. First, on a P-type silicon substrate (10)
An element isolation region consisting of an active region and a field oxide film
After forming an element formation region,
SiO2 as oxide film_TwoElement type with film (2) formed
3500-4000 mm thick polysilicon on the active area
Of a gate electrode (3) made of
_TwoA film is deposited to a thickness of 2500-3500 °
SiO on the side wall of electrode (3)_TwoSidewall consisting of
(4) using reactive ion etching (RIE) method and HF
It is formed by wet etching and
Approximately 100 to 400 ° of SiO_Twofilm
Form (6).

Then, using the gate electrode (3) as a mask, ion implantation of an N-type impurity such as As is performed on the region serving as the source / drain region (8) via the SiO ₂ film (6) through the source / drain region (8). 8) (FIG. 2)
(A)). Then, in order to diffuse the generated impurities in the source / drain regions (8), for example, a medium temperature heat treatment is performed at a temperature of 800 ° C. for one hour.

Thereafter, an NSG film (11) is deposited on the SiO ₂ film (6) in order to suppress outward diffusion of the source / drain region (8), and an interlayer step on the NSG film (11) is formed thereon. A BPSG film (12) is deposited to reduce the temperature, and a high-temperature heat treatment is performed at, for example, 950 ° C. for 30 minutes to form a source / drain region (8) (FIG. 2B).

[0005]

One of the causes of variations in the characteristics of the fine MOS transistor is the presence of crystal defects in the source / drain regions. However, in the above-described method for manufacturing a semiconductor device, since the ion implantation is performed through the SiO ₂ film (6), a silicon implanted ions when passing through the SiO ₂ film (6), an oxygen atom of the SiO ₂ film (6) in along with recoil has been implanted ions Oxygen implanted into the silicon substrate (10) will be implanted into the substrate (10).
There is a problem that a crystal defect (7) is generated in 0).

Further, the crystal defect (7) does not disappear even in the subsequent heat treatment, causing an electric leak of the semiconductor device and a reduction in the yield. The present invention has been made in view of such problems, and has as its object to provide a method for manufacturing a semiconductor device having a high yield without generating crystal defects.

[0007]

According to the present invention, in order to solve the above-mentioned problems, according to the present invention, a source of a semiconductor substrate in which a gate electrode having a sidewall formed on a side wall is disposed via a gate oxide film. A step of performing an intermediate temperature heat treatment by ion-implanting impurities through a oxide film into a portion serving as a / drain region, and a step of performing a high temperature heat treatment in an ammonia atmosphere after removing the oxide film on the semiconductor substrate. Features.

In the present invention, the intermediate temperature heat treatment is performed at 750 to 8
It is preferable to carry out in a temperature range of 50 ° C. for 30 to 60 minutes. The high-temperature heat treatment performed in an RTA apparatus under an ammonia atmosphere is performed in a temperature range of 1000 to 1100 ° C.
It is preferably performed for up to 60 seconds.

[0009]

According to the method described above, crystal defects such as insertion-type stacking faults generated in a semiconductor substrate when ions are implanted into a source / drain region through an oxide film are eliminated. That is, by performing the high-temperature heat treatment in the NH ₄ atmosphere of RTA, Si atoms are ejected from the semiconductor substrate in the high-temperature NH ₄ atmosphere, and holes are forcibly introduced into the semiconductor substrate. Then, the holes eliminate defects generated in the semiconductor substrate to form impurity-free impurity diffusion regions.

[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, silicon substrate (1)
An element formation region consisting of an active region and a field oxide film is formed thereon to secure an element formation region, and an SiO ₂ film (2) is laminated as a gate oxide film. A gate electrode (3) made of polysilicon having a thickness of 3 nm is formed. Then, Si is formed as an oxide film on the gate electrode (3) by a CVD method.
An O ₂ film is deposited to a thickness of 2500-3500 °, and a sidewall (4) made of SiO ₂ is formed on the side wall of the gate electrode (3) by reactive ion etching (RIE) and HF.
An SiO ₂ film (6) of about 100 to 400 ° is formed on the silicon substrate (1) while being formed by a wet etching method.

Next, using the gate electrode (3) as a mask, an impurity such as As is ion-implanted into the source / drain region (5) at 80 KeV and 5 × 10 ¹⁵ ions / cm ² to form the source / drain region (5). (FIG. 1)
(A)). Then, in order to diffuse the generated impurities in the source / drain regions (5), for example, a middle-temperature heat treatment is performed at a temperature of 800 ° C. for one hour.

Thereafter, the gate electrode (3) and the SiO ₂ film (6) on the silicon substrate (1) are removed, and RTA (Rapid) is removed.
Thermal annealing is performed at a high temperature of 1000 ° C. for 30 seconds in an NH ₄ atmosphere in the apparatus. In the silicon substrate (1) of the semiconductor device manufactured as described above, when ions are implanted through the SiO ₂ film (6), crystal defects (7) such as insertion type stacking faults are formed in the silicon substrate (1). Occurs. Therefore, by performing a high-temperature heat treatment in an NH ₄ atmosphere for a short time, the vacancies can be forcibly introduced into the silicon substrate (1), and the stacking fault (7) formed in the silicon substrate (1) can be formed. Disappeared and a uniform surface was confirmed.

[0013]

According to the method of manufacturing a semiconductor device according to the present invention, high-temperature heat treatment is performed for a short time in an ammonia atmosphere, so that holes are formed in insertion-type defects generated in a semiconductor substrate ion-implanted through an oxide film. Can be enforced. Therefore, a defect-free impurity diffusion region can be formed, the leak current can be reduced, and the yield is improved.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic sectional views of a waist showing an embodiment of a method of manufacturing a semiconductor device according to the present invention.

FIGS. 2A and 2B are schematic cross-sectional views of a waist showing manufacturing steps of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

Reference Signs List 1 silicon substrate (semiconductor substrate) 2 SiO ₂ film (gate oxide film) 3 gate electrode 4 sidewall 5 source / drain region 6 SiO ₂ film

Claims (1)

(57) [Claims] An impurity is ion-implanted through an oxide film into a portion to be a source / drain region of a semiconductor substrate in which a gate electrode having a sidewall formed on a side wall is disposed via a gate oxide film. A method for manufacturing a semiconductor device, comprising: a step of performing a medium temperature heat treatment; and a step of performing a high temperature heat treatment in an ammonia atmosphere after removing an oxide film on a semiconductor substrate.