JPH05182959A - Method of isolating semiconductor element utilizing local polyoxide - Google Patents

Abstract

PURPOSE: To provide an element isolating method with good electric characteristics even for the isolation of a 0.5 μm design role essential to the development of a highly integrated element of >=16 M bits as one of isolating methods utilizing a silicon substrate by making good use of polysilicon and eliminating a bird's beak generated by a LOCOS method. CONSTITUTION: This is a method which uses polysilicon as a material of silicon at the time of oxidation so as to form oxide for element separation; and an oxide film 12 is grown on the silicon substrate 11 and a nitride film 13 is formed to form a nitride film pattern as well as the LOCOS method. After oxide grown by etching and oxidizing a polysilicon film 15 is etched to above the nitride film by utilizing an etching baking process, the nitride film and oxide film are etched similarly to the advance in the LOCOS process to form the oxide for element separation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for isolating a semiconductor device, and more particularly, it utilizes polysilicon to provide LOCOS.
OS: Local oxidation of sil
Bird's beak (Bird's)
Local poly-oxidation required to develop a device with good electrical characteristics, in which the size of the bird's beak shape) is reduced and the impurity ions etc. implanted into the silicon substrate during the oxidation process are not redispersed by the oxide film. The present invention relates to a method for isolating a semiconductor device using an object.

[0002]

2. Description of the Related Art Generally, with the progress of research on high integration of semiconductors, a technique for separating semiconductor elements on the same substrate encounters an important problem on a chip array.

Currently, in manufacturing a 64M DRAM, isolation between elements is required to 0.5 μm or less, and Bird's beak generated in the LOCOS method for manufacturing such a semiconductor element is reduced. Must.

Accordingly, in the proposed device isolation method, the conventional isolation (Is) using a trench is used.
a lot of interest was concentrated in the early stage of development, and research is still in progress.

However, the trench (Tr
nch) element isolation (Isolation)
Many problems remain in the method and the like in the process and electrical characteristics.

In addition, the presently proposed isolation (Isolati
On method, etc., the isolation method used most for 16M DRAM is LOCOS.
OS) process is improved.

However, the element isolation limit applicable to the element in the manufacturing process utilizing this plane is about 0.7 μm.

To this end, the present invention is one of isolation methods using a plane, and utilizes polysilicon (LOCOS).
Bird's b generated by the OS method
eak) and redispersion of impurities (Redistr)
i.b.), which is essential for the development of highly integrated devices of 16 Mbit or more. 0.5 μm isolation (Isolatio)
n) is also applicable and, subsequently, an element isolation method having good electrical characteristics is provided.

The present invention is easy to reduce the chip area and is applicable to high integration.

2A to 2E show a device isolation method utilizing the conventional LOCOS method. FIG. 2A shows a process of forming an oxide film (2) with a predetermined thickness on the upper surface of a silicon substrate (1) and forming a nitride film (3) with a predetermined thickness on it.

FIG. 2B shows a photolithography (Photolithography) after forming a photosensitive film (4) on the above.
The pattern formation of the nitride film (3) is illustrated by using the (Raphy) process.

FIG. 2C shows a channel stop (Channel).
The process of injecting an impurity (I ² P) for el stop and performing oxidation is shown.

FIG. 2D shows a process of growing the element isolation oxide film (5).

FIG. 2E shows an oxide film (6) formed by etching the nitride film (3) and etching the oxide film (2).

Such a technique is described in US Pat.
965221 and the like.

[0016]

In the above manufacturing process,
Impurities for channel stop are caused by the oxidation process (Ox
An oxide film located on the silicon substrate to match a chemical potential during the idation process is redistributed, and thus electrical characteristics for device isolation are deteriorated.

Also, the bird's beak becomes large because the oxidation process is performed with only the nitride film having a predetermined pattern formed on the oxide film.

In such a process, high integration is required6
In a manufacturing process of 4M DRAM or less, there are problems that are not applied.

Accordingly, the present invention is directed to a general locos (LO
Bird's beak generated by the COS method
It is an object of the present invention to provide a manufacturing method using a local polyoxide required for high integration by reducing the size of (break) and at the same time preventing redispersion of impurities.

[0020]

According to the features of the present invention,
A method for isolating a semiconductor device includes a step of sequentially stacking an oxide film (12) and a nitride film (13) on a silicon substrate (11),
Forming a channel block layer by applying a photoresist film (14) on the nitride film (13) and removing a nitride film on a portion where an oxide film for element isolation is formed by using a photolithography process; In order to implant impurities into the silicon substrate (11), forming a polysilicon film (15) thereon, and oxidizing the polysilicon film (15) to form a polyoxide. Poly oxide film (1
6) and a step of forming the field oxide film (17), the poly oxide film (16) is replaced with the nitride film (13).
Etching and removing even the surface, and the nitride film (13)
And a step of etching and removing the oxide film (12) in order.

According to another feature of the present invention, in the impurity implanting step, oxide spacers (28) are formed on the sidewalls of the oxide film and the nitride film in the impurity implanting region, and then impurities are implanted to isolate the semiconductor device. Can be done.

Explaining the specific steps, a method of isolating a semiconductor device is as follows: a step of sequentially forming an oxide film (22) and a nitride film (23) on silicon (21);
3) A step of removing the nitride film (23) and the oxide film (22) on the surface of the silicon substrate (21) on which a device isolation oxide film is formed after forming a photosensitive film (24) of a predetermined pattern on the surface. And a step of forming an oxide film spacer (28) in the etching of the oxide film (22) and the nitride film (23), and the silicon substrate after removing the photoresist film having the predetermined pattern to form a channel blocking layer. A step of injecting impurities into (21), a step of forming a polysilicon layer (25) on the exposed portion of the patterned nitride film and the substrate, and a step of forming the polysilicon layer (25) into a poly oxide film. The step of oxidizing and forming the poly oxide film (26), the step of etching the poly oxide film (26) to the upper surface of the nitride film, and the step of forming the field oxide film in order to form the field oxide film Eclipse Characterized in that it comprises a step of.

According to another aspect of the present invention, a method of isolating a semiconductor device is provided with an oxide film (42) on a silicon substrate (41).
And a buffering polysilicon film (43) and a nitride film (44) are sequentially stacked, and a photolithography process is performed after applying the photosensitive film (45) on the nitride film (44) to oxidize for device isolation. A step of removing the nitride film on the portion where the film is formed, a step of implanting impurities in the silicon substrate (41) to form a channel support layer, and a polysilicon film (46) formed thereon. A step of forming a polyoxide film (47) after oxidizing the polysilicon film (46) to form a polyoxide, and a step of forming the polyoxide film (4) to form a field oxide film (48).
7) a step of etching and removing the surface of the nitride film (44) and a step of sequentially etching and removing the nitride film (44), the polysilicon film (43) and the oxide film (12).

[0024]

The manufacturing process of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1A to 1G show an element isolation method according to an embodiment of the present invention. In FIG. 1A, an oxide film (12) is grown on a silicon substrate (11) to a thickness of about 10 to 100 nm, and a nitride film (3) is formed on the upper surface of the oxide film (3) to 100 to 100 nm.
It shows a process of forming with a thickness of about 200 nm.

FIG. 1B shows a photosensitive film (Photores).
ist) (14) and photolithography (P
The pattern (Pattern) of the nitride film (13) formed using the photolithography process is shown.

FIG. 1C shows a channel stop (Cha).
Impurities (1E13-1E1) due to nnel Stop
5) shows the injection.

In FIG. 1D, a polysilicon film (Polysil) is used to form an element isolation oxide for element isolation.
Ion) (15) is formed with a thickness of about 100 to 400 nm.

FIG. 1E shows a poly oxide (Poly o).
In order to manufacture xide), the polysilicon (1
5 shows a process of forming a poly oxide film (16) after oxidizing (5).

In FIG. 1F, the poly oxide film 16 is etched and baked up to the upper side of the nitride film 13.
The process of forming a field oxide film (17) for device isolation after performing back etching is shown.

FIG. 1G shows a nitride film (3) and an oxide film (1).
It shows the form after etching 2) in order.

In the embodiment described above, the oxidation process is performed after the polysilicon layer 15 is entirely formed on the exposed portions of the patterned nitride film 13 and the oxide film 12. In addition, it becomes possible to prevent the impurity ions already implanted in the semiconductor substrate during the oxidation step from being re-diffused into the oxide film of the semiconductor substrate or the field region.
In addition to improving the electrical characteristics of the device for device isolation, the size of any Bird's beak in the polysilicon layer (15) having a buffer function can be reduced.

3A to 3G show an element isolation method according to the second embodiment of the present invention. In FIG. 3A, an oxide film (22) is grown on a silicon substrate (21) to a thickness of about 10 to 100 nm, and a nitride film (23) is formed on the upper surface of the oxide film (22) by about 10 nm.
It indicates that the film is formed with a thickness of about 0 to 200 nm.

In FIG. 3B, the photosensitive film (2
4) is formed, and photolithography (Photol
The nitride film (2
The pattern formation of 3) is shown.

FIG. 3C shows polysilicon (Polysi).
In order to prevent the surface of the silicon substrate (1) from being oxidized during the oxidation of the silicon film (25), an oxide spacer (Oxide spa) is formed on the side surface of the nitride film or the oxide film.
cer) (28) forming the channel stop (Ch
Impurities (1E13-1) due to annel stop
The process of injecting E15) is shown.

FIG. 3D shows the above-mentioned polysilicon film of about 10
After being applied to a thickness of about 0 to 400 nm, this polysilicon film (26) is oxidized to form a poly oxide film.

As described above, the poly oxide (Poly oxi)
After the polysilicon (25) is oxidized to manufacture de), a poly oxide film (2) is formed as shown in FIG.
6 shows a process of etching after applying 6).

In FIG. 3F, the poly oxide film (26) is etched to the upper side of the nitride film (23) by etching bake.
ck), field oxide (2
7) shows the formation of 7).

Prior to forming the polysilicon layer (25) in the second embodiment described above, the oxide spacers (28) are formed and the impurity ions already implanted in the substrate to proceed with the oxidation. Is not re-diffused, the electrical characteristics are improved due to device isolation, and Bird's Beak (Bird's
Not only can the size of the (break) be reduced, but also the surface of the semiconductor substrate can be prevented from being oxidized due to the oxidation spacer.

FIGS. 4A to 4G show an element isolation method according to the third embodiment of the present invention. FIG. 4A shows that an oxide film (42) is formed on a silicon substrate (41) in an amount of about 10 to 100 n.
The growth is performed to a thickness of about m, a buffer polysilicon film (43) is formed on its upper surface to a thickness of about 50 to 200 nm, and a nitride film (44) is formed thereon to a thickness of about 100 to 200 nm. It shows a process of forming (deposit).

In FIG. 4B, a nitride film (44) is etched using a nitride film mask, and a photosensitive film (Photo) is formed thereon.
The pattern formation is shown in the nitride film (44) using the resist.

The above process is compared with the LOCOS method, and the first polysilicon film 43 acts as a buffer between the oxide film 42 and the nitride film 44 during the oxidation. ..

FIG. 4C shows the implantation of impurities (1E13-1E15) for removing the photosensitive film (45) and for channel stop (ChannelStop).

FIG. 4D shows a manufacturing process in which a polysilicon film (46) is formed with a thickness of about 100 to 400 nm to form an element isolation oxide.

FIG. 4E shows a process of forming the polyoxide (47) after oxidizing the polysilicon film (46) to manufacture the polyoxide.

In FIG. 4F, the poly oxide film (47) is etched and baked (Etch) up to the middle portion of the nitride film (44).
A process of forming a field oxide film (48) for element isolation after performing back is shown.

FIG. 4G shows a nitride film (4
4) is removed and the polysilicon first film 43 and the oxide film 42 are sequentially etched to form an oxide film 49.

In the above embodiment, the buffer polysilicon layer (4
3) is formed between the oxide film (42) and the nitride film (44) on the silicon substrate (41), and impurity ions and the like implanted into the substrate (41) are not further diffused into the field region during the oxidation process. ..

That is, by forming the polysilicon layer 43, the degree of re-diffusion of the impurity ions can be reduced as desired in comparison with the first and second embodiments.

Therefore, according to the present invention, a polysilicon film (Polysilicon) is formed and oxidized as compared with the conventional process, and an etching bake process is added, but the process is relatively simple and the device is relatively simple. There is no re-dispersion of impurities for channel stop due to utilizing polysilicon for isolation oxide, and at the same time oxide bird's beak for device isolation.
There is an advantage that k) does not become large.

Thus, the present invention is particularly useful for providing a highly integrated DRAM device. Other various modifications can be easily and easily carried out by a person having ordinary skill in the art without departing from the spirit and scope of the present invention.

Therefore, the scope of the appended claims is not limited by the contents of the specification described herein, and includes all novel features of the present invention for which patent is granted, and the technology to which the present invention belongs. Includes every feature that is treated as an equivalent by business operators in the field.

[0053]

According to the present invention, a general locos (LO
Bird's beak generated by the COS method
It is possible to provide a manufacturing method using a local polyoxide required for high integration by reducing the size of the peak) and at the same time preventing redispersion of impurities.

[Brief description of drawings]

1A to 1G are cross-sectional views of steps illustrating a method for isolating a semiconductor device using a local polyoxide according to an embodiment of the present invention.

FIG. 2 (A) to (E) are conventional locos (LOCO).
Sectional drawing which shows the element isolation method using S).

3A to 3G are cross-sectional views of steps illustrating a method for isolating a semiconductor device using a local polyoxide according to a second embodiment of the present invention.

4A to 4G are cross-sectional views of steps illustrating a semiconductor device isolation method using a local polyoxide according to a third embodiment of the present invention.

[Explanation of symbols]

 1, 21, 31 Silicon substrate 2, 22, 32 Oxide film 3, 23, 33 Nitride film 4, 24, 34 Photosensitive film 15, 25 Polysilicon 16, 26 Poly oxide film 17, 27 Field oxide film 28 Spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Lee Ho-sung, Quan-dong, Jung-dong, Dong-gu, Korea 9-408

Claims (3)

[Claims] 1. A semiconductor manufacturing method comprising: an oxide film (12) and a nitride film (1) formed on a silicon substrate (11).
3) are sequentially laminated, and a photolithography (Photolithography) is performed after applying a photosensitive film (14) on the nitride film (13).
y) a step of removing the nitride film on the portion where the element isolation oxide film is formed by using the step, and a step of implanting impurities into the silicon substrate (11) to form a channel blocking layer, A step of forming a polysilicon film (15) thereon, a step of oxidizing the polysilicon film (15) to form a polyoxide and then forming a polyoxide film (16), and a field oxide film (17). ), The poly oxide film (16) is etched to the surface of the nitride film (13) and removed, and the oxide film (13) and the oxide film (1) are removed.
2. A method for isolating a semiconductor device using a local polyoxide, comprising the step of sequentially etching and removing 2). 2. A semiconductor manufacturing method comprising: an oxide film (22) and a nitride film (2) formed on a silicon substrate (21).
3) are formed in sequence, a nitride film (23) formed on the surface of the silicon substrate (21) on which a device isolation oxide film is formed after a photosensitive film (24) having a predetermined pattern is formed on the nitride film (23). ) And the oxide film (22) are removed, a step of forming an oxide film spacer (28) in the etching of the oxide film (22) and the nitride film (23), and the above-mentioned predetermined process for forming the channel blocking layer. A step of implanting impurities into the silicon substrate (21) through the exposed portion of the oxide film (22) after removing the photoresist film of the pattern; and a polysilicon layer on the exposed portion of the nitride film and the substrate of the pattern. A step of forming (25), a step of oxidizing the polysilicon layer (25) to form a poly oxide film (26), a step of etching the poly oxide film (26) to the upper surface of the nitride film, and a field. Oxidation The semiconductor device isolation method using a local poly oxide, which comprises the step of sequentially etching the nitride film and an oxide film of the pattern to be formed. 3. A method for manufacturing a semiconductor, comprising a step of sequentially laminating an oxide film (42), a buffer polysilicon film (43) and a nitride film (44) on a silicon substrate (41), and the nitride film (44). A step of removing the nitride film on the portion where the oxide film for element isolation is formed by using a photolithography process after applying the photosensitive film (45) thereon, and impurities for forming a channel blocking layer are added as described above. The step of implanting into the silicon substrate (41), the step of forming a polysilicon film (46) on it, and the step of forming the polysilicon film (4) to form the polysilicon oxide film (47).
6) a step of oxidizing the oxide film and a step of removing the polyoxide film (47) to the surface of the nitride film (44) to form a field oxide film (48), the nitride film (44) and the polysilicon film A method of isolating a semiconductor device using a local polyoxide, comprising a step of etching (43) and an oxide film (12) in order.