JPH05129593A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] [Structure] Impurity is ion-implanted through the oxide film into the source / drain region of the semiconductor substrate in which the gate electrode having the sidewall is provided through the gate oxide film. Then, the first heat treatment is performed, the oxide film on the semiconductor substrate is removed, a silicide film is laminated to form a contact pad, and then the second heat treatment is performed. Method. [Effect] Insertion type defects that occur in the semiconductor substrate ion-implanted through the oxide film can be eliminated by directly depositing silicide on the semiconductor substrate and performing high temperature treatment. Further, the step coverage can be improved by using the silicide as the contact pad of the bit line. Therefore, it is possible to reduce the leak current and to manufacture a highly reliable semiconductor device with high yield.

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 A method of manufacturing a conventional MOS type memory cell having an LDD (Lightly Doped Drain) structure will be described with reference to FIG. First, an element isolation region including an active region and a field oxide film is formed on a P-type silicon substrate (11) to secure an element formation region, and then a SiO ₂ film (12) is formed as a gate oxide film. A gate electrode (13) made of polysilicon having a thickness of 3500 to 4000 Å is formed on the device forming region, and S is formed by a CVD method.
An iO ₂ film is deposited to a thickness of 2500 to 3500Å, and a sidewall (14) made of SiO ₂ is formed on the gate electrode (13) by a reactive ion etching (RIE) method and H.
It is formed by the F wet etching method, and about 100 to 400 Å SiO ₂ is formed on the silicon substrate (11).
A film (21) is formed.

Then, using the gate electrode (13) as a mask, SiO _{2 is formed in the} regions to be the source / drain regions (16).
Ion implantation of N-type impurities such as As is performed through the film (21) (FIG. 2A). Then, in order to diffuse the impurities in the source / drain regions (16), for example, 800 ° C.
The first heat treatment is performed at the temperature of 1 hour.

After that, in order to suppress out-diffusion of the source / drain regions (16), NS is formed on the SiO ₂ film (21).
A G film (17) is deposited, a BPSG film (18) is deposited thereon to reduce the interlayer step on the NSG film (17), and a second heat treatment is performed at 950 ° C. for 30 minutes, for example. Source / drain regions (16) are formed. Then, a contact hole (22) is opened above the source / drain region (16) by a photoetching process, and, for example, AlSi (19) to be a first wiring layer is deposited to form a bit line (FIG. 2B). ).

[0005]

The existence of crystal defects (20) in the source / drain regions (16) can be cited as one of the causes of fluctuations in various characteristics of the fine MOS transistor. of the manufacturing method, since the ion implantation is performed through the SiO ₂ film (21), when implanted ions pass through the SiO ₂ film (21), an oxygen atom of the SiO ₂ film (21) in the recoil As a result, the ions are implanted into the silicon substrate (11) together with the implanted ions, and the oxygen implanted in the silicon substrate (11) has a problem that crystal defects (20) are generated in the silicon substrate (11).

Further, there has been a problem that the crystal defects (20) are not eliminated even by the subsequent heat treatment, which causes an electric leak of the semiconductor device and a decrease in yield. The present invention has been made in view of such problems, and an object thereof is to provide a method for manufacturing a semiconductor device having a high yield without causing crystal defects.

[0007]

In order to solve the above-mentioned problems, according to the present invention, a source / drain of a semiconductor substrate in which a gate electrode having a sidewall is provided via a gate oxide film A step of ion-implanting an impurity into a region to be a region and performing a first heat treatment; a step of removing an oxide film on a semiconductor substrate and thereafter forming a silicide film to form a contact pad; It is characterized by including a step of performing a second heat treatment afterwards.

In the present invention, a semiconductor substrate (for example,
A gate oxide film (eg, SiO 2) is previously formed on the silicon substrate.
_The gate electrode is formed by forming the sidewall through the _two films). Then, this semiconductor substrate has an oxide film (for example, SiO 2) on the entire surface including the gate electrode portion.
₂ film) is formed. As, which is an impurity, is diffused through the oxide film into the source / drain regions of the semiconductor substrate.
Ion implantation of P or the like is performed by a known method.

Then, in the present invention, this impurity is added to the source / source.
A first heat treatment is performed to diffuse into the drain region. This first heat treatment can be achieved by performing the first heat treatment in the temperature range of about 750 to 850 ° C. for about 30 to 60 minutes. Then, after removing the oxide film of the semiconductor substrate by a known method, a silicide film is laminated to form a contact pad. MoSi ₂ , WSi ₂ , or TiSi ₂ can be used for the silicide formed as the contact pad, and it is preferable to stack the WSi film by 300 to 800 Å by a known method such as a sputtering method. Then, after that, a second heat treatment is performed. By performing the second heat treatment at about 800 to 900 ° C. for 10 to 30 minutes, a defect-free impurity diffusion region can be formed.

[0010]

According to the method described above, crystal defects such as insertion type stacking faults that occur in the semiconductor substrate when ions are implanted into the source / drain regions through the oxide film are formed by directly depositing silicide on the semiconductor substrate. , The second processing causes the second processing to disappear. That is, W that is a silicide
The Si film receives tensile stress on the silicon substrate, which is a semiconductor substrate, and Si / WSi is used to relax the stress.
At the interface, Si atoms are introduced from the semiconductor substrate into the WSi film, and the vacancies are forcedly introduced into the silicon substrate to form a defect-free impurity diffusion region.

Further, the step coverage is improved by utilizing the silicide deposited directly on the semiconductor substrate for the contact pad of the bit line.

[0012]

EXAMPLE An example of a method of manufacturing a semiconductor device according to the present invention will be described with reference to FIG. First, silicon substrate (1)
An element formation region is secured by forming an element isolation region composed of an active region and a field oxide film thereon, and a SiO ₂ film (2) is laminated as a gate oxide film. Then, 3500 to 4000 Å Forming a gate electrode (3) of polysilicon having a thickness of. 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 to 3500Å, and a sidewall (4) made of SiO ₂ is formed on the gate electrode (3).
Is formed by reactive ion etching (RIE) method and HF wet etching method, and a SiO ₂ film of about 100 to 400 Å is formed on the silicon substrate (1). Then, using the gate electrode (3) as a mask, the source /
Impurities such as As are added to the region to be the drain region (9) through the SiO ₂ film at 80 KeV, 5 × 10 ¹⁵ ions / c.
Ion implantation is performed with m ² to form source / drain regions (9) (FIG. 1A). Then, in order to diffuse the generated impurities in the source / drain regions (9), for example, 8
A first heat treatment is performed at a temperature of 00 ° C. for 1 hour.

After that, the SiO ₂ film on the gate electrode (3) and the silicon substrate (1) is removed, and a WSi film is laminated to about 800 Å by, for example, a sputtering method. 5) (FIG. 1A). Then, an NSG film (6) is deposited on the gate electrode (3) and the contact pad (5), and a BPSG film (7) is deposited on the NSG film (6) to reduce an interlayer step on the NSG film (6). , A second heat treatment for 30 minutes at 950 ° C.
A drain region (9) is formed. Then, the NSG film (6) and the BPSG film (7) above the contact pad (5)
A contact hole (10) is opened by a photoetching process, and a first wiring layer, for example, AlSi (8) is deposited to form a bit line (FIG. 1).
(B)).

[0014]

According to the method of manufacturing the semiconductor device of the present invention, the silicide is directly deposited on the semiconductor substrate, and the second
By performing the heat treatment of (1), voids can be forcibly introduced into the semiconductor substrate, and crystal defects such as insertion type stacking faults generated in the semiconductor substrate can be eliminated. Further, the step coverage can be improved by using the silicide deposited on the semiconductor substrate as the contact pad of the bit line.

Therefore, a defect-free impurity diffusion region can be formed, a leak current can be reduced, and a highly reliable semiconductor device can be manufactured with a high yield.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view of a waist showing a manufacturing process of a conventional semiconductor device manufacturing method.

[Explanation of symbols]

1 Silicon substrate (semiconductor substrate) 2 SiO ₂ film (gate oxide film) 3 Gate electrode 4 Sidewall 5 Contact pad 9 Source / drain region

Claims (1)

[Claims] 1. A first electrode is formed by ion-implanting an impurity through an oxide film into a portion of a semiconductor substrate in which a gate electrode having a sidewall is formed through a gate oxide film, which is to be a source / drain region. Of the semiconductor device, the step of removing the oxide film on the semiconductor substrate, the step of stacking a silicide film to form a contact pad, and the step of performing the second heat treatment. Production method.