KR20010016698A - Method of forming shallow trench isolation layer in semiconductor device - Google Patents

Abstract

PURPOSE: A method for manufacturing a shallow-trench-isolation(STI) type isolation layer of a semiconductor device is provided to prevent a blowing-up phenomenon of a nitride layer in a high temperature oxide process, by using a buffer layer composed of a nitride layer and an oxide layer which are formed in a trench. CONSTITUTION: A pad oxide layer and a pad nitride are sequentially stacked on a semiconductor substrate(10). After the pad nitride layer and the pad oxide layer are patterned by performing a photolithography process using an isolation mask, a trench is formed in the substrate to a predetermined depth. A nitirde layer and an oxide layer are sequentially deposited in the trench to form a multilayered buffer layer for reducing stress of the substrate of the trench and a gap fill oxide layer(22) to be formed later. After the gap fill oxide layer is filled and planarized in the trench of the substrate having the buffer layer, the pad nitride layer is eliminated to form an isolation layer.

Description

Method of forming shallow trench isolation layer in semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device isolation method of a semiconductor device. In particular, a thin nitride film is used as an oxidation barrier after trench etching, and subsequently, a blow-up phenomenon of the nitride film can be prevented due to the gapfill oxide process of the trench. A method of forming an STI type isolation film for a semiconductor device.

Recently, as the development of semiconductor device manufacturing technology and the application of memory devices have been expanded, the development of large-capacity memory devices has been progressed. It has been promoted by a memory cell study. In particular, the reduction of the device isolation film that separates the devices has emerged as one of the important items in the technology of miniaturization of memory devices.

Conventional device isolation technology has mainly been a LOCal Oxidation of Silicon (LOCOS) technology to selectively grow a thick oxide film on the semiconductor substrate to form a device isolation film. However, the LOCOS technique cannot reduce the width of the device isolation region due to side diffusion and bird's beak of the device isolation layer. Therefore, the LOCOS technology cannot be applied to a large-capacity memory device whose device design dimension is reduced to less than a submicron, and thus, a new device isolation technology is required.

As a result, a trench capable of electrically separating devices by forming trenches having a width of about 1Å or less and a depth of several tens to hundreds of Å on a semiconductor substrate due to the necessity of a new device isolation technology and the development of etching technology. Device isolation technology has emerged. The device isolation technology using this trench can reduce the device isolation region by nearly 80% compared to the conventional LOCOS technology.

Moreover, recently, the STI (Shallow Trench Isolation) process, which greatly reduces the stress applied to the wafer substrate and improves the problem of the trench isolation layer, has emerged. In other words, the STI process is a technique of forming a device isolation film by forming a trench having a predetermined depth in the semiconductor substrate, depositing an oxide film on the trench by chemical vapor deposition, and etching an unnecessary oxide film by a chemical mechanical polishing process.

For example, in the prior art STI type isolation film manufacturing process, a pad oxide film is formed on a silicon substrate, and a pad nitride film is laminated thereon. The pad nitride layer and the pad oxide layer are patterned by a photolithography and an etching process using a device isolation mask, and the substrate exposed by the patterned layer is selectively etched to form trenches up to a predetermined depth.

Subsequently, a thermal oxide film is formed in the trench to remove the surface charge trap, and then a liner nitride thin film is formed on the entire surface of the substrate. In this case, the thin nitride film serves as an oxidation barrier for removing the etch pit by infiltrating oxygen of the substrate during a high-temperature gap fill oxide film deposition process.

Then, using a high density plasma (HDP), the trench is completely filled with a gap fill oxide film, and the pad nitride film is used as an etch stop film, and the nitride film remaining after the gap fill oxide is flattened by a chemical mechanical polishing process is removed. To form.

However, in the conventional STI type device isolation process, the liner nitride film is blued-up due to the stress generated during the gapfill oxide film process. The blue-up phenomenon of the nitride film in the substrate may cause defects during high temperature thermal processing in the device fabrication process, thereby lowering the electrical characteristics of the device.

An object of the present invention is to bluish the nitride film during the high temperature oxidation process of the gapfill oxide film by forming an oxide film by chemical vapor deposition before or after the deposition of the liner nitride film which serves as an oxidation barrier after the trench etching to solve the problems of the prior art as described above An object of the present invention is to provide a method for forming an STI type device isolation film in a semiconductor device which can prevent the up-up.

1A to 1D are flowcharts illustrating a method of forming an STI type isolation layer in a semiconductor device according to an embodiment of the present invention.

2 is a cross-sectional view illustrating an isolation layer of a semiconductor device in accordance with another embodiment of the present invention;

3 is a cross-sectional view illustrating an STI type isolation film of a semiconductor device according to still another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10 silicon substrate 12 pad oxide film

14: pad nitride film 16: trench

18: nitride film 20: oxide film

22: gap fill oxide ISO: device isolation film

In order to achieve the above object, the present invention provides a method of forming a device isolation film having a trench structure for defining an active region and an isolation region of a device on a semiconductor substrate, the method comprising sequentially depositing a pad oxide film and a pad nitride film on the semiconductor substrate; Forming a trench to a predetermined depth of the substrate after patterning the pad nitride layer and the pad oxide layer by performing a photolithography process and an etching process using a separation mask; and depositing a nitride layer / oxide layer sequentially in the trench to form a substrate of the trench and a gap fill to be formed thereafter. Forming a multilayer buffer film to alleviate stress of the oxide film, and filling the gap fill oxide film in the trench of the substrate on which the buffer film is formed, and planarizing it, and then removing the pad nitride film to form a device isolation film on the substrate. It is done.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1A to 1D are flowcharts illustrating a method of forming an STI type device isolation film of a semiconductor device according to an embodiment of the present invention. Referring to this, an embodiment of the device isolation process of the present invention is as follows.

First, as shown in FIG. 1A, a thin pad oxide film 12 of about 30 to 100 microseconds and a pad nitride film 14 of 500 to 2000 microsecond thickness are sequentially stacked on a silicon substrate 10 as a semiconductor substrate. After the photoresist film (not shown) for device isolation mask is applied thereon, a dry etching process is performed to pattern the pad nitride film 14 and the pad oxide film 12 and to expose the substrate by the patterned films 14 and 12. The trench 16 is formed in 10. At this time, the trench 16 may have an etching depth that varies depending on the design rules of the applied device, but in the present embodiment, the trench 16 may be etched at about 2000 to 4000 microseconds. In addition, for accurate patterning during the trench etching process, an anti-reflective film that prevents diffuse reflection may be further stacked on the pad nitride layer 14 by about 200 to 500 mW.

Then, as shown in FIGS. 1B and 1C, the nitride film 18 / oxide film 20 is sequentially deposited in the trench 16 to relieve stress of the trench substrate and the gap fill oxide film to be formed later, thereby bluing the nitride film. A multilayer buffer film is formed to prevent -up.

In this embodiment, the buffer film has a structure in which the nitride film 18 and the oxide film 20 are stacked. Here, the nitride film 18 serves as an oxidation barrier to prevent etching pits by infiltrating oxygen from the substrate during the high temperature gap fill oxidation process. In addition, the oxide film 20 is deposited by chemical vapor deposition of any one of tetra-etly-ortho-silicate, monostyrene (SiH ₄ ), and dichlorosilane (SiH ₂ Cl ₂ ). Get

In addition, the thickness of the nitride film 18 is preferably 50 to 80 kPa, and the thickness of the oxide film 20 is preferably 30 to 150 kPa.

Next, as shown in FIG. 1D, the gapfill oxide film 22 is buried in the trench of the substrate on which the nitride film 18 and the buffer film of the oxide film 20 are formed by using an HDP (High Density Plasma) method. After polishing the gap fill oxide film 22 until the pad nitride film 14 is exposed, the pad nitride film 14 is removed with a phosphoric acid solution to form an STI type isolation film ISO according to the present invention.

2 is a cross-sectional view illustrating a device isolation film of a semiconductor device according to another embodiment of the present invention. Referring to this, the device isolation process of the present invention is as follows.

First, a trench etching process is performed in the same manner as in the above-described embodiment, and a conventional thermal oxidation process (dilution film, sidewall oxide film deposition) is performed to prevent surface charge traps due to trench etching damage in the trenches of the substrate.

Subsequently, after depositing the oxide film 30 to a thickness of 100 kPa by chemical vapor deposition, the liner nitride film 32 is deposited to about 70 kPa to form a multilayer buffer film that relieves stress of the trench substrate and the gap fill oxide film to be formed thereafter. The rest of the process proceeds. Therefore, in the present embodiment, the buffer film of the oxide film and the nitride film structure is formed in the trench, thereby improving adhesion of the nitride film and preventing the bluing-up phenomenon during the gap fill oxide film process.

3 is a cross-sectional view illustrating an STI type device isolation film of a semiconductor device according to still another embodiment of the present invention. Referring to this, another STI type device isolation process of the present invention is as follows.

As in FIG. 1A, a trench etching process is performed on the substrate.

Next, as shown in FIG. 3, the first oxide film 40 is deposited to a thickness of 100 GPa, the liner nitride thin film 42 is deposited to about 70 GPa, and then the second oxide film 44 is deposited to a thickness of 100 GPa. A multilayer buffer film is formed to reduce the stress of the substrate of the trench and the gapfill oxide film to be formed later, and to prevent the blueing-up phenomenon of the nitride film. Thereafter, the gap fill oxidation process and the planarization process are performed to form an STI type isolation layer ISO.

Accordingly, the device isolation film according to the embodiment of the present invention includes an oxide film, a nitride film, and an oxide film buffer layer in the trench, so that the etching rate of the oxide film before and after the nitride film is the same during the planarization process. moat) to improve the phenomenon.

As described above, the present invention further provides an oxide film by chemical vapor deposition before or after the deposition of the nitride film in the manufacturing process of the device isolation film including the liner nitride film as an oxide barrier in the trench to remove the etch pit in the substrate.

Accordingly, the buffer film formed of the nitride film and the oxide film in the trench prevents the blue-up phenomenon of the nitride film during the high temperature oxidation process of the gapfill oxide film and prevents the mott phenomenon occurring at the edge of the device isolation film, thereby improving the electrical characteristics of the device. Improve.

Claims (6)

In forming a device isolation film having a trench structure to define an active region and an isolation region of a device on a semiconductor substrate, Sequentially depositing a pad oxide film and a pad nitride film on a semiconductor substrate; Forming a trench to a predetermined depth of the substrate after patterning the pad nitride layer and the pad oxide layer by performing a photolithography and an etching process using a device isolation mask; Sequentially depositing a nitride film / oxide film in the trench to form a multilayer buffer film that relieves stress of the substrate of the trench and the gapfill oxide film to be formed later; And And forming a device isolation film on the substrate by filling the gap fill oxide film into the trench of the substrate on which the buffer film is formed, and planarizing the gap fill oxide, thereby forming a device isolation film on the substrate. The method of claim 1, wherein the oxide film of the buffer film is formed by depositing any one of tetraethyl orthosilicate, monosilylene, and dichloroxylene by chemical vapor deposition. The method for forming an STI type device isolation film for a semiconductor device according to claim 1, wherein the nitride film constituting said buffer film is 50-80 GPa, and the oxide film constituting said buffer film is 30-150 GPa. The method of claim 1, wherein the gap fill oxide film is deposited by a high density plasma method. In forming a device isolation film having a trench structure to define an active region and an isolation region of a device on a semiconductor substrate, Sequentially depositing a pad oxide film and a pad nitride film on a semiconductor substrate; Forming a trench to a predetermined depth of the substrate after patterning the pad nitride layer and the pad oxide layer by performing a photolithography and an etching process using a device isolation mask; Sequentially depositing an oxide film / nitride film in the trench to form a multilayer buffer film that relieves stress of the substrate of the trench and the gapfill oxide film to be formed later; And And forming a device isolation film on the substrate by filling the gap fill oxide film into the trench of the substrate on which the buffer film is formed, and planarizing the gap fill oxide, thereby forming a device isolation film on the substrate. In forming a device isolation film having a trench structure to define an active region and an isolation region of a device on a semiconductor substrate, Sequentially depositing a pad oxide film and a pad nitride film on a semiconductor substrate; Forming a trench to a predetermined depth of the substrate after patterning the pad nitride layer and the pad oxide layer by performing a photolithography and an etching process using a device isolation mask; Sequentially depositing an oxide film / nitride film / oxide film in the trench to form a multilayer buffer film that relieves stress of the substrate of the trench and the gapfill oxide film to be formed thereafter; And And forming a device isolation film on the substrate by filling the gap fill oxide film into the trench of the substrate on which the buffer film is formed, and planarizing the gap fill oxide, thereby forming a device isolation film on the substrate.