JPS62296438A - Device for manufacturing semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To increase capacity in a capacitor region for the improvement of an element in its stability by a method wherein a bird's beak is removed by etching after selective oxidation for the exposure of the semiconductor substrate surface and then an insulating film, electrode layer, etc., are formed in order. CONSTITUTION:An oxidation-resistant mask 14 built of a silicon nitride film is removed by using a heated solution of phosphoric acid. A process follows wherein a wet etching technique involving fluoric acid or a conventional plasma dry etching technique is applied to a pad oxide film 12, field oxide film 16, and bird's beak 16a for the exposure of the surface of a silicon substrate 11, whereby the width of the field 16 is so patterned as to be equivalent to the width of an opening 13, that is, to the distance between two broken lines A-A and B-B. After this, in a conventional MOS-manufacturing process, an approximately 200Angstrom -thick insulating film 17, which is a silicon oxide film for a capacitor region 11b, and an approximately 3500Angstrom -thick polycrystalline silicon electrode layer 18 are built, in that order. Difference in the surface of a capacitor region 11c in the vicinity of a field region 11a allows the surface area of the capacitor region 11b to be enlarged.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and in particular to a storage capacitor (hereinafter referred to as a canopy) in which information is stored by charge accumulation. The present invention relates to a method of manufacturing a bottom portion (referred to as a bottom portion).

[Conventional technology]

When manufacturing an integrated circuit by forming a large number of elements on a semiconductor substrate, it is necessary to electrically insulate and separate each element. Conventionally, selective oxidation has been widely used as a method for insulating and isolating each element. This selective oxidation method has the advantage of being able to form element regions and field regions in a self-aligned manner, and is currently considered the best method for device-to-device isolation. It is essential for manufacturing.

Hereinafter, a conventional example will be explained based on FIG.

First, as shown in FIG. 2(a), on a semiconductor substrate 21 made of a silicon substrate, a Nomurad oxide film (Sigh) 22 of about 500A and an oxidation-resistant film made of a silicon nitride film (SiiN4) are sequentially formed to about a zoooi degree. .

After coating, apply resist and turn.
A resist mask (not shown) is formed, and an opening 23 is formed in the silicon nitride film using a conventional selective etching method to form an oxidation-resistant mask 24. A channel stop region 25 is formed in the silicon substrate 21 by performing channel stop implantation via the silicon substrate 21.

Then, the resist mask is removed, and the pad oxide film 22 in the opening 24 is removed using a hydrofluoric acid-based etchant.

Next, as shown in FIG. 2(b), when oxidation treatment is performed in a high-temperature oxidation atmosphere, the field oxide film (St(h)
26 to about 6000A. At this time, bird's beaks 26 a dZ are generated due to lateral oxidation.

Thereafter, according to a normal MOS process, a silicon oxide film (insulating film 27 made of SiC2) for the capacitor portion 1b is formed.
By sequentially forming electrode layers 28 made of polysilicon (Poly-St) of about 200 Å and about 3 sooi, a cross-sectional structure as shown in FIG. 1(C) is obtained. Here, a region having a pattern width W obtained by adding the nose peak amounts on both sides to the @ of the opening 23 is a field region 21a, and 21b is an element region, here a capacitor portion. Furthermore, as is clear from the figure, the capacitor section 21b
is approximately horizontal near the field region 21a (IEICE Technical Research Report Semiconductor/Transistor 5)
(See SD77-23P, 1-9).

[Problem that the invention seeks to solve]

However, in the conventional example described above, when a field oxide film is formed by selective oxidation, lateral oxidation progresses and bird's beaks occur. The occurrence of this Z-beak is a serious hindrance in achieving higher density because it excessively expands the field area and narrows the element area within the limited chip area.

For example, when using the element region as a capacitor section,
Since the effective area of the capacitor section is reduced, there is a problem in that it is difficult to obtain sufficiently stable device characteristics.

By the way, in order to eliminate the above-mentioned bird's beak, a so-called trench method has been announced in which a trench is provided in a silicon substrate and an insulating film is buried in the trench to insulate and separate the shield region and the element region.

However, this trench method differs in technique from the conventional selective oxidation method, and requires difficult techniques such as etching.

Therefore, it is an object of the present invention to provide a method for developing a semiconductor device that can solve the above-mentioned problems, increase the area of the canopy of the device region, and realize higher density and higher stability of the device. shall be.

[Means for solving problems]

In the semiconductor device staging method according to the present invention, after forming a field oxide film by selective oxidation, the oxidation-resistant mask is removed by etching, and the pad oxide film, field oxide film, and bird's beak are removed to the extent that the bird's beak is substantially removed. is etched at the same time, and then an insulating film and an electrode layer are sequentially formed.

[For production]

As described above, according to the present invention, bird's beaks generated due to lateral oxidation during selective oxidation are removed by etching in the post-process.

Therefore, a reduction in the area of the element region due to the generation of a crystal peak can be avoided. Further, since the surface of the element region has a sloped shape due to the occurrence of bird's beak near the field region, the surface area increases, and when this is used as a canopy part, the canopy capacitance can be increased.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail based on FIG.

First, as shown in FIG. 1(a), a P-type silicon substrate (10
0) (hereinafter abbreviated as silicon substrate), a pad oxide film 12 made of a silicon oxide film (SiOz) of about 500A is grown by high-temperature oxidation in an oxidizing atmosphere of about 1000°C, and then Then, an oxidation-resistant film made of a silicon nitride film (S1sN4) is grown to a thickness of about 1500 Å using the CVD method. Next, a resist pattern (not shown) is formed and etched through the resist pattern to form an opening 13 in the silicon nitride film to form an oxidation-resistant mask 14.

Then, 30 KeV was applied through this oxidation-resistant mask 24.
.

B"O ions are implanted under implantation conditions of about 2.times.10.sup.13/- to form a T-type channel stop region 15 in the silicon substrate 11. Then, the resist mask and the rad oxide film 12 in the opening 13 are removed.

Here, the width of the opening 130 is W, and the width of the opening 130 is W, as shown in FIG.
The pattern width is the same as that of the field area 21a shown in C). That is, the field area 21a in FIG. 2(C)
The pattern width W in this figure 1(a) is wider than the width of the opening 23 shown in FIG. 2(a) by the width of the bird's beak 26a on both sides shown in FIG. The width of the opening 13 shown in ) is increased by the amount of bird's beak.

As described above, in this embodiment, the pattern width of the field area 11a that is finally obtained as described later is set as shown in the vlc2 diagram (
It is set to have the same dimensions as the conventional field area 21a shown in c), so that the effect of the present invention becomes clear.

Next, as shown in ) in the figure, selective oxidation is performed in a high-temperature oxidizing atmosphere through an oxidation-resistant mask 14 to grow a field oxide film 16 of about 10,000 Å. Note that during this selective oxidation, nose peak 1 is generated due to lateral oxidation.
6a occurs.

Next, as shown in FIG. 2C, the oxidation-resistant mask 14 made of silicon nitride film is removed using a hot phosphoric acid solution, and the pad oxide film is removed using hydrofluoric acid wet etching or ordinary plasma dry etching. 12. The field oxide film 16 and the bird's beak 16a are etched to expose the surface of the silicon substrate 11, and the pattern width of the field oxide film 16 is adjusted to the width of the opening 13 shown in FIG. (a), Φ) both broken lines A-A and B-B
The width should be narrowed by .

Thereafter, as shown in FIG. 1(d), a silicon oxide film for the capacitor portion 1b (
The insulating film 17 made of Polysilicon (Stow) is about 200mm thick, and the electrode layer 18 made of polysilicon (Poly-8T) is about 350mm thick.
Gradually grow to about 0A. In the figure, 11a indicates a field region, and llb indicates an element region as a canopy-side portion.

Here, as is clear from the comparison between FIG. 1(d) and the above-mentioned FIG. 2(c), both field regions 11a and 21a
have the same width W. Also, both capacitor parts 1 l b.

The widths of 21b are also the same in plan view.

However, in the case of the present invention, as shown in FIG. 1(d), the surface shape of the capacitor portion 11c near the field region 11a is sloped due to the occurrence of the bird's beak 16a, whereas in the conventional example, It is a substantially horizontal plane as shown in FIG. 2(c).

Therefore, the capacitor section 11 near the field region 11a
Due to the difference in surface shape c, in the case of the present invention, the surface area of the capacitor portion 11b can be made much larger.

〔Effect of the invention〕

As explained in detail above, the present invention takes advantage of the bird's beak, which is a serious obstacle in increasing the density of devices, by etching away the bird's beak after selective oxidation to expose the surface of the semiconductor substrate. Furthermore, an insulating film, an electrode layer, etc. are sequentially formed.

Therefore, it is possible to avoid a decrease in the integral of the element area due to the occurrence of the 1,6-beak beak, and by using the slope part of the semiconductor substrate after removing the bird's beak as a capacitor part, the capacitance of this canopy part can be increased, and the element This has the effect of improving the stability of.

Furthermore, the increased area of the capacitor section utilizing the bird's beak shape will occupy a larger proportion of the total area of the capacitor as the density of the device progresses, and therefore the effects of the present invention will become more significant.

[Brief explanation of drawings]

FIG. 1 is a process sectional view explaining one embodiment of the present invention, gg
FIG. 2 is a process sectional view explaining a conventional example. 11... Semiconductor substrate (P-type St substrate (100)), 1
1a... Field region, llb, llc... Element region (capacitor section), 12... Pad oxide film (Si
O2), 13... Opening, 14... Oxidation-resistant mask (S 1sN4), 15... Channel stop region (
P+ type), 16... field oxide film (Si(h),
16a... Bird's beak, 17... Insulating film (Sig
h), 1830. Electrode layer (Poly-8i). Patent applicant Oki Electric Industry Co., Ltd.! ! ! /! l-NNN Eve L xi Akira Turuko 1 Rihi road! "Face 0 Figure 1

Claims (1)

[Claims] (1) In a method of manufacturing a semiconductor device in which devices are insulated and separated by a thick field oxide film, (a) two layers of a pad oxide film having openings on a semiconductor substrate and an oxidation-resistant mask are formed by a conventional method; forming a field oxide film by performing selective oxidation through the film; (b) after etching and removing the oxidation-resistant mask, simultaneously etching the pad oxide film, field oxide film, and bird's beak to the extent that the bird's beak is removed; etching to expose the surface of the semiconductor substrate, and insulating and separating the semiconductor substrate into a field region and an element region using the remaining field oxide film; (c) After this, an insulating film and an electrode layer are removed by a conventional method 1. A method for manufacturing a semiconductor device, the method comprising the steps of sequentially forming a semiconductor device.