JPH03270153A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an impurity region in a self-aligned manner by avoiding the part of a bird's beak of an oxide film by a method wherein an insulating film is left so as to be wider than the oxide film formed by a selective oxidation method and impurities are introduced into a semiconductor substrate by making use of the remaining insulating film as a mask. CONSTITUTION:An SiO2 film 16 formed by a selective oxidation method is covered; a resist pattern 19 is left from the end part of a bird's beak of the SiO2 film 16 up to its outside at about 0.1mum. Then, SiO2 films 18, 12 are etched and removed by making use of the resist pattern 19 as a mask; then, an element region (A) and an element isolation region (B) are formed. Then, arsenic ions are implanted selectively into an Si substrate 11 by making use of a gate electrode 21 and an SiO2 film 18a in the element isolation region (D) as a mask; after that, a heat treatment is executed; As is diffused deep; S/D regions (impurity regions) 22a to 22d are formed. Then, an SiO2 film is formed on the whole surface; after that, it is etched anisotropically; an SiO2 film 23 for insulation use of the gate electrode 21 is formed; then, a MIS transistor is completed.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figure 2) Examples of means and actions for solving the problem to be solved by the invention (Figure 1) Effects of the invention [Summary] Regarding a method of manufacturing a semiconductor device, more specifically, regarding a method of manufacturing a semiconductor device that includes a step of forming an element isolation region by a selective oxidation method, crystal distortion due to the selective oxidation method is generated in a semiconductor substrate. The purpose of the present invention is to provide a method for manufacturing a semiconductor device that can prevent the effect from affecting the element region even when the semiconductor substrate has an opening, and selectively processes the semiconductor substrate by using an anti-oxidation film on the semiconductor substrate as a mask. a step of oxidizing and forming an oxide film within the 080 portion; a step of removing the anti-oxidation film; a step of depositing an insulating film on the semiconductor substrate and covering the oxide film; selectively forming a mask and selectively removing the insulating film using the mask;
The method includes a step of remaining in a width larger than the width of the formed oxide film, and a step of introducing conductive impurities into the semiconductor substrate using the remaining insulating film as a mask to form an impurity region.

[Industrial use bone def]

The present invention relates to a method of manufacturing a semiconductor device, and more specifically, to a method of manufacturing a semiconductor device including a step of forming an element separation region by a selective oxidation method.

[Prior Art] FIGS. 2(a) to 2(d) show a conventional method of forming an element switching region using an MIS (MetaI-1nsuIator).
-5eaicoductor) FIG. 5 is a cross-sectional view illustrating a case where the method is applied to fabrication of a transistor.

First, as shown in the same figure (a), a SiO2 film as a reaction prevention film for a 5iJn film on a Si substrate is formed on a p-type Si substrate 1.
□After sequentially forming film 2 and 5iJ4H3 as an oxidation prevention film, these are patterned to form element isolation regions (B
) is formed in the region where the opening 4 is to be formed. Subsequently, p-type impurity ions are selectively implanted into the Si substrate 1 through the opening 4. As a result, the s+ substrate 1 at the bottom of the opening 4
An ion implantation region 5 is formed.

Next, as shown in FIG. 4(b), Si
The surface of the substrate 1 is selectively thermally oxidized. As a result, SiO□WIJ6 is formed in the element swing region (B), and
Impurities that have already been introduced also diffuse and spread, and StO□
A p° type isolation diffusion region 5a is formed at the periphery of the film 6.

Next, after removing Si3N and M3, the entire surface is etched to remove the 5in2 film 2. Next, through the usual process, Si0
Then, a gate electrode 8 is formed (FIG. 3(c)).

Next, as shown in the same figure (d), using the gate electrode 8 and sio and J12a of the element switching region (B) as a mask, S
i on board 1! By introducing a large amount of n-type impurities, the source
Drain (S/D) 61 regions 9a to 9d are formed.

Thereafter, as shown in FIG. 2(e), an insulating film is formed to insulate the gate electrode 8 from the S/D electrode (not shown). After forming O, the MIS transistor is completed.

(18 to be solved by the invention) By the way, the selective oxidation method shown in FIG. 2(b)
N. It is inevitable that a bird's beak will occur at the opening 4@ of the 5iJalffff2 due to the strain caused by the stress exerted on the St substrate 1 from the bite 2.

Therefore, as shown in FIG. 6(e), since distortion remains in the St substrate l under the bird's beak, the pn junctions of the S/D regions 9a to 9d formed here and the s
+Crystal defects may occur in the substrate 1, and leakage current tends to flow through these crystal defects. Therefore, S/
Since the leakage current between the Delf regions 9a to 9d and the Si substrate increases, there is a problem that the paste freshness characteristics of semiconductor memories and the like deteriorate.

The present invention has been made in view of these conventional problems, and aims to prevent crystal distortion caused by selective oxidation from affecting the element region even if crystal distortion occurs in the semiconductor substrate. It is an object of the present invention to provide a method for manufacturing a semiconductor device that allows for the manufacturing of semiconductor devices.

(Means for Solving the Problems) The above problems include a step of selectively oxidizing the semiconductor substrate using an oxidation prevention film on the semiconductor substrate having an opening as a mask to form an oxide film in the opening; A step of removing the anti-oxidation film and applying tI! on the semiconductor substrate. , Ii n
'J, to cover the oxide film, selectively forming a mask on the surface of the insulating film, selectively removing the insulating film using the mask, and removing the formed oxide film. A method for manufacturing a semiconductor device, comprising: a step of leaving H in a width larger than the width; and a step of introducing a conductivity type impurity into a semiconductor substrate using the remaining insulating film as a mask to form an impurity region. achieved.

[Function] According to the method for manufacturing a semiconductor device of the present invention, since the insulating film remains with a width larger than the width of the oxide film formed by the selective oxidation method, this remaining insulating film is masked. By introducing impurities into the semiconductor substrate, an impurity region can be formed in a self-aligned manner avoiding the bird's beak portion of the oxide film.

Thereby, even if crystal distortion occurs in the semiconductor substrate due to stress from the 5iJa WJ used in the selective oxidation method, it can be prevented from affecting the element region.

[Example] Hereinafter, examples of the present invention will be specifically described with reference to the drawings.

FIGS. 1(a) to 1(h) show a method for forming an element isolation region using a selective oxidation method according to an embodiment of the present invention using MIS (Meta
l-Insulator-5emiconductor
) FIG. 2 is a cross-sectional view illustrating a case where the method is applied to fabrication of a transistor.

First, as shown in the same figure (a), a reaction prevention film between the Si substrate 11 and Si, N, and films was formed on a p-type Si5 plate (semiconductor substrate) 11 by thermal oxidation at a temperature of 900°C. The P! Film thickness 500 CV D (Che+5ical Vapor Dep
A 513N4 WIJl 3 having a thickness of about 1000 Å is formed on the 5i02 film 12 by the 513N4 WIJl 3 film (position) method.

Next, after forming a resist pattern having an opening (not shown) in the region where the element isolation region (B) is to be formed, Si, N, selectively etching film I3. Subsequently, the 5i02 film 12 is etched by a dry etching method using C11h gas to form an opening 14, and then the Si-based Fi film at the bottom of the opening 14 is etched.
, acceleration voltage 100 keV dose Ill XIO”
Boron, which is a p-type impurity, is selectively ion-implanted under the condition of "cm-" to selectively form an ion-implanted region 15 (FIG. 3(b)).

Next, a thermal oxidation method using wet 02 gas was applied to the residual 5i3Na v! at a temperature of 1000°C. (Anti-oxidation Jlff) Using 13a as a mask, Si substrate 11 is
Jj! , SLO□N is heavily oxidized and has a film thickness of approximately 3000 mm.
(Oxide film) 16 is formed, and poron in the ion implantation region 15 is diffused deeper to form a p'-type isolation diffusion region 15a. At this time, Si, N, rPj, 1
A bird's beak 17 is formed at the periphery of the opening 14 due to distortion due to the stress from 3a. (Figure (C)).

Next, after removing the remaining 5isN and film 13a, CV
D (Chemical Vapor Deposit
A 510□ film (
An insulating film) 18 is formed ((d) in the same figure).

Next, a SiO□ film 16 formed by a selective oxidation method is coated, and 0
．． The resist pattern 19 is left to the outside by about 17 ym.

Next, using the resist pattern 19 as a mask, SiO□I
When IΔ18.12 is etched and removed, the element region (
A) and elemental RjJ 'pm region (B) are formed (
Figure (e)).

Next, the Si substrate 11 is thermally oxidized to form an SiO2 film 2 with a thickness of about 300 in the element region (A) to the gate oxidation number.

After forming, a polysilicon film having a thickness of about 3000 Å, which will become a gate electrode, is formed by CVD. Subsequently, this polysilicon film is patterned to form a gate electrode 21 (FIG. 4(f)).

Next, Si of the gate electrode 21 and the element isolation region (B) is
Using the NG film 18a as a mask, apply i! to the Sil temporary 11! After a large amount of arsenic (As) is ion-implanted, heat treatment is performed, and A
Diffuse s deeply to create S/D ftI region (impurity region)
22a to 22d are formed. In addition, the reference numeral 22c in the figure.

22d is an adjacent M! through the fin expansion rPi region 15a.
s! This is the S/D fi, II region of the transistor ((g) in the same figure).

Next, after forming a 510□ film on the entire surface, anisotropic etching is performed to complete a 3-film type 3MIS transistor with 23 SiO□ films for insulating the gate electrode 21 ((h) in the same figure).
.

As described above, according to the embodiment of the present invention, since the upper SiO film I8a remains in a width larger than the width of the SiO□M16 formed by the selective oxidation method, this remaining SiO□ film By introducing As into the Si substrate 11 using 18a as a mask, a bird's beak 1 of 5 to J l 6 is formed.
S/D areas 22a to 22 in a self-aligned manner avoiding the part 7.
d can be formed.

Therefore, even if crystal distortion occurs in 5iIvil due to stress from the 5iiNa film 13a used in the selective oxidation method, it can be prevented from affecting the element region (A).

Therefore, the S/DH region 22a caused by crystal distortion
An increase in leakage current between ~22d and the Si substrate 11 can be prevented.

Thereby, it is possible to increase the density and improve the characteristics and reliability of the semiconductor device.

〔Effect of the invention〕

As described above, according to the method for manufacturing a semiconductor device of the present invention, since the upper insulating film remains with a width larger than the width of the insulating film formed by the oxidation method, this remaining insulating film By introducing impurities into the semiconductor substrate using the mask as a mask, an S/D region or the like as an impurity region can be formed in a self-aligned manner while avoiding the bird's beak portion of the insulating film formed by selective oxidation.

Therefore, even if crystal distortion occurs in the semiconductor substrate due to stress from the 5izes film used in the selective oxidation method, it can be prevented from affecting the element region.

Therefore, an increase in leakage current between the S/DeM region and the semiconductor substrate due to crystal distortion can be prevented.

Thereby, it is possible to increase the density and improve the characteristics and reliability of the semiconductor device.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating a method for creating an element bone N region according to an embodiment of the present invention, and FIG. 2 is a sectional view illustrating a method for creating an element isolation region in a conventional example. [Explanation of symbols] 1...Si substrate, 2.6, 10.12, 20.23...5i02 film, 3
...SiJ, film, 4.14...opening, 5□ 15...ion implantation region, 5a, 15a...isolation diffusion region, 7a, 20a...gate oxide film, 8.21.・・Gate electrode, 9 a to 9d・−3/Df+1 region, 11・Si substrate (semiconductor substrate), 13.13a”・SiJ, n (oxidation prevention gas, 16・
...SiO□ film (oxidized W!J), 17...Bird's beak, 1 B, 18a ・=SlOt film (insulating film), 19
...Resist pattern, 22a to 22d-S/D fiJl region (impurity region), A...device region, B...device isolation region.

Claims (1)

[Claims] a step of selectively oxidizing the semiconductor substrate using an oxidation prevention film on a semiconductor substrate having an opening as a mask to form an oxide film in the opening; a step of removing the oxidation prevention film; depositing an insulating film on and covering the oxide film; selectively forming a mask on the surface of the insulating film; and selectively removing the insulating film using the mask;
The method is characterized by comprising a step of remaining in a width larger than the width of the formed oxide film, and a step of introducing a conductivity type impurity into the semiconductor substrate using the remaining insulating film as a mask to form an impurity region. A method for manufacturing a semiconductor device.