KR100529607B1 - A method for manufacturing a semiconductor device using a shallow trench isolation - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a trench of a semiconductor device by dry etching after coating a lower organic antireflection film (BARC) during photoresist patterning in a semiconductor device having a shallow trench isolation (STI) structure. A method of manufacturing a semiconductor device using an STI according to the present invention includes the steps of: i) forming a pad oxide film and a nitride film on a semiconductor substrate; Ii) forming a bottom antireflective coating (BARC) on the nitride film; Iv) forming a photoresist film on the coated lower anti-reflection film, and patterning the photoresist to form a mask pattern; Iii) dry etching the lower anti-reflection film according to the first set of process conditions using the mask pattern as a mask; Iv) dry etching the nitride film according to a set second process condition using the mask pattern as a mask; And iii) further etching the pad oxide film and the silicon substrate exposed to the portion where the nitride film is etched to form a trench. According to the present invention, according to the detailed conditions of the dry etching process described above, it is possible to efficiently etch the BARC on the upper part of the nitride film, and to suppress the generation of voids when forming the trench separator due to the rounded portion of the upper part of the nitride film.

Description

A method for manufacturing a semiconductor device using a shallow trench isolation

The present invention relates to a method of manufacturing a semiconductor device using shallow trench isolation (STI), and more particularly, to a semiconductor device having an STI structure, a bottom organic antireflective coating (Bottom AntiReflective Coating: Hereinafter, the present invention relates to a method of forming a trench in a semiconductor device by coating a 'BARC') and performing dry etching.

In a semiconductor circuit, it is necessary to electrically isolate various elements such as transistors, diodes, and resistors formed on the semiconductor substrate. In addition, as the integration of semiconductor devices has progressed, fine patterns have been required in manufacturing devices, and the channel length of transistors and the width of field oxide films for device isolation have also been reduced.

As a method for forming such device isolation, a conventional LOCal Oxidation of Silicon (LOCOS) has been most commonly used.

The LOCOS device isolation is performed by sequentially forming a pad oxide film and a nitride film on a silicon substrate, patterning the nitride film, and selectively oxidizing the silicon substrate to form a field oxide film. In the selective oxidation of the silicon substrate, a bird's beak is generated at the end of the field oxide layer as oxygen penetrates into the side of the pad oxide layer under the nitride layer used as a mask. Since the field oxide film is extended to the active region by the length of the buzz beak by such a buzz beak, a so-called short channel effect is generated in which the channel length is shortened and the threshold voltage is increased, resulting in the electrical characteristics of the transistor. Worsens. In particular, the LOCOS device isolation exhibits limitations such as a punch-through occurs in which field oxide films on both sides of the active region are stuck as the channel length is reduced to 0.3 μm or less, thereby not accurately securing the width of the active region. It was.

Therefore, trench device isolation methods have been discussed in recent semiconductor manufacturing processes manufactured with design rules of 0.25 mu m or less. That is, a trench technique of partially etching the semiconductor substrate to form a predetermined trench between the devices and separating the devices is applied.

Recently, a silicon substrate is locally etched to form a trench at the time of device isolation, an insulating film (eg, an oxide film) is deposited, and an insulating film on the active region is etched by a chemical mechanical polishing (CMP) process. A shallow trench isolation (STI) technique is mainly used in which an insulating film remains only in the field region. In particular, the STI technique for forming the trench depth shallower than 3 µm has been applied to design rules of 0.15 µm or less without major problems.

The STI process may include forming a trench by etching a silicon substrate to a predetermined depth, depositing an insulating layer on the trench and the substrate, and etching the insulating layer by etching the entire surface by a back etching or a CMP method. Filling or filling the inside with an insulating film. Currently, undoped silicate glass (USG), tetra-ethyl-ortho-silicate (TEOS), high temperature oxide (HTO), or a combination thereof is used as an oxide film to fill a trench. The above materials have a lower heat budget and a higher throughput than the thermal oxide formed by the oxidation process, while the wet etching rate is fast. Therefore, when the trench oxide layer filled with the above materials is exposed to the surface, the trench oxide layer is etched much faster than the active region when the photoresist strip or hydrogen fluoride (HF) wet etching is performed in a subsequent process.

Hereinafter, a process of forming a device isolation layer using the STI technique according to the prior art will be described in detail with reference to FIGS. 1A to 1D.

1A to 1G are diagrams illustrating a semiconductor device isolation process using the STI technique according to the prior art.

As shown in FIG. 1A, a pad oxide film 13 and a nitride film 15 made of a thermal oxide film are sequentially formed on the silicon substrate 11.

Next, a photoresist (PR) 17 is applied on the pad oxide film 13 and the nitride film 15 (see FIG. 1B), and the photoresist film 17 is exposed and removed so that only the upper side of the device isolation region is removed. Develop (see FIG. 1C).

Thereafter, the trench A is formed by etching the nitride film 15, the pad oxide film 13, and the silicon substrate 11 by a dry etching method using the photosensitive film 17 ′, which has been selectively exposed and developed, as a mask. (See FIG. 1D). The trench A thus formed is for forming a shallow trench isolation (STI) element.

However, the technology of forming a device isolation layer using the STI technique according to the related art causes problems such as pattern bridge, descum, and CD uniform dimension uniformity due to reflection characteristics of the nitride layer. There is a problem.

An object of the present invention for solving the above problems is to provide a method for manufacturing a semiconductor device using the STI that can give a round to the upper end of the nitride film to suppress the generation of voids when forming the trench isolation film of the semiconductor device.

As a means for achieving the above object, a method of manufacturing a semiconductor device using the shallow trench isolation (Shallow Trench Isolation: STI) according to the present invention,

Iii) forming a pad oxide film and a nitride film on the semiconductor substrate;

Ii) forming a bottom antireflective coating (BARC) on the nitride film;

Iv) forming a photoresist film on the coated lower anti-reflection film, and patterning the photoresist to form a mask pattern;

Iii) dry etching the lower anti-reflection film according to the first set of process conditions using the mask pattern as a mask;

Iv) dry etching the nitride film according to a set second process condition using the mask pattern as a mask; And

Iii) further etching the pad oxide layer and the silicon substrate exposed to the portion where the nitride layer is etched to form a trench;

It includes.

Here, the lower anti-reflection film and the photosensitive film are preferably coated with a thickness of about 400 ~ 700 Å and 4000 ~ 5000 각각 respectively.

In addition, the etching of the lower anti-reflection film is preferably dry etching using high frequency power (RF Power) of 300 to 500 Watt while maintaining a pressure of 30 to 60 mTorr.

Here, the CHF ₃ is 10 to 50 sccm, the CF ₄ is 30 to 60 sccm, and the O ₂ is preferably injected at 5 to 15 sccm.

In order to track an etch end point of the lower anti-reflection film, a wavelength of about 4000˜5000 장비 is monitored by using an optical emission system (OES) device.

On the other hand, the nitride film is preferably dry etching using a high frequency power of 200 to 300 Watt while maintaining a pressure of 30 to 60 mTorr.

Here, the nitride film is preferably dry etching by injecting a reaction gas of CHF ₃ , Ar and O ₂ , the CHF ₃ is 40 to 80 sccm, the Ar is 5 to 50 sccm, and the O ₂ is 3 to 10 sccm is preferably injected.

And, in order to track the end point of etching of the nitride film using the OES equipment to monitor the wavelength of about 3700 ~ 3900Å.

Here, the additional etching of the step iii) may be additionally etched by about 50 to 100% than the etching of the iii) step.

According to the present invention, according to the detailed conditions of the dry etching process described above, it is possible to efficiently etch the BARC on the nitride film, and due to the rounded portion of the nitride film, it is possible to suppress the generation of voids when forming the trench separator of the semiconductor device.

Hereinafter, a method of manufacturing a semiconductor device using shallow trench isolation (STI) according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In order to improve the above-described problems of the prior art, a method of applying a pattern after applying BARC (Bottom AntiReflective Coating: BARC), which is a lower anti-reflection film, which prevents reflection of light, is used. Etching conditions for dry etching the wafer after application are presented.

2A to 2G are views illustrating a manufacturing process of a semiconductor device using an STI according to the present invention.

First, a 100-200 kPa pad oxide film 23 is grown on the silicon substrate 21, and a nitride film 25 of about 1000-2000 kPa is grown thereon (see FIG. 2A). Thereafter, BARC is formed on the order of 400 to 700 m 3 (see FIG. 2B). Next, the photoresist film 29 having a thickness of about 4000 to 5000 m is coated on the BARC 27 (see FIG. 2C), and then the photoresist film 29 is patterned to form a mask pattern 29 ′ (see FIG. 2D). ).

Subsequently, BARC 27 is etched using the following first process conditions (see FIG. 2E).

That is, etching is performed using a high frequency power (RF Power) of 300 to 500 Watt while maintaining a pressure of 30 to 60 mTorr. In this case, 10 to 50 sccm of CHF ₃ , 30 to 60 sccm of CF ₄ , and 5 to 15 sccm of O ₂ are injected into the reaction gas. In order to track an end point of the BARC 27, a wavelength of about 4000˜5000 μm is monitored using an optical emission system (OES) device. Here, reference numeral B denotes a portion where the BARC 27 'is etched.

Next, the nitride film 25 is etched using a second process condition (see FIG. 2F). At this time, the etching of the nitride film 25 is performed using a high frequency power of 200 to 300 Watt while maintaining a pressure of 30 to 60 mTorr. In addition, 40 to 80 sccm of CHF ₃ , 50 to 50 sccm of Ar, and 3 to 10 sccm O ₂ are injected into the reaction gas. At this time, in order to track the end point of the etching of the nitride film 25 using the OES equipment to monitor the wavelength of about 3700 ~ 3900Å. Here, reference numeral 25 'denotes a nitride film after etching is completed, and reference numeral C denotes a portion where the nitride film 25' is etched.

Subsequently, at a time when the pad oxide layer 23 'and the silicon substrate 21' are exposed, an etching of about 50 to 100% is additionally performed (see FIG. 2G). Here, reference numeral D denotes a trench formed by further etching.

In the etching method described above, when the nitride film etching step is performed after the BARC 27 is etched, etching is further performed on the upper edge portion of the nitride film 27 ′ to form a round.

3 is a photograph showing that a round is formed in the upper end of the nitride film during BARC etching according to the present invention, reference E shows that the round is formed in the upper end of the nitride film.

As a result, the detailed conditions of the above-described dry etching process can efficiently etch the BARC on the nitride film, and can suppress the generation of voids during the trench isolation of the semiconductor device due to the rounded portions of the nitride film. .

While the invention has been described above, these examples are intended to illustrate rather than limit this invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments are possible without departing from the technical details of the present invention.

In the method of manufacturing a semiconductor device using the STI according to the present invention, the upper portion of the nitride film may be rounded to suppress voids that may occur when forming the trench isolation layer of the semiconductor device.

1A to 1D are diagrams illustrating a device isolation layer forming process using STI according to the prior art.

2A to 2G are views illustrating a manufacturing process of a semiconductor device using an STI according to the present invention.

Figure 3 is a photograph showing that a round (round) is formed in the upper portion of the nitride film during BARC film etching according to the present invention.

Claims (10)

In the method for manufacturing a semiconductor device by using shallow trench isolation (STI), Iii) forming a pad oxide film and a nitride film on the semiconductor substrate; Ii) forming a bottom antireflective coating (BARC) on the nitride film; Iv) forming a photoresist film on the lower anti-reflection film and patterning the photoresist to form a mask pattern; Iii) Drying the lower anti-reflection film according to the first process conditions set to the reaction gas consisting of CHF ₃ , CF ₄ and O ₂ , a pressure of 30 to 60 mTorr, and a high frequency power of 300 to 500 Watt using the mask pattern as a mask. Etching; Iii) dry etching the nitride film according to a second process condition set to a reaction gas consisting of CHF ₃ , Ar and O ₂ , a pressure of 30 to 60 mTorr, and a high frequency power of 200 to 300 Watt using the mask pattern as a mask ; And Iii) further etching the pad oxide layer and the silicon substrate exposed to the portion where the nitride layer is etched to form a trench; Method for manufacturing a semiconductor device using a shallow trench isolation comprising a. delete The method of claim 1, CHF ₃ is 10 to 50 sccm, CF ₄ is 30 to 60 sccm, and O ₂ is 5 to 15 sccm under the first process conditions, the method of manufacturing a semiconductor device using a shallow trench isolation. . The method of claim 3, wherein the wavelength of about 4000 to 5000 GHz is monitored by using an optical emission system (OES) to track an etch end point of the lower anti-reflection film in the step iii). A method of manufacturing a semiconductor device using shallow trench isolation. delete The method of claim 1, In the second process conditions, CHF ₃ is 40 to 80 sccm, Ar is 5 to 50 sccm, and O ₂ is a method of manufacturing a semiconductor device using a shallow trench isolation, characterized in that the injection. The method of claim 6, Method of manufacturing a semiconductor device using a shallow trench isolation characterized in that for monitoring the end point of the etching of the nitride film of step iii) using the OES equipment to monitor the wavelength of about 3700 ~ 3900Å. The method of claim 6, The additional etching of the step iii) is about 50 to 100% more than the etching of the iii) step further etching method of manufacturing a semiconductor device using a shallow trench isolation. The method of claim 6, The lower anti-reflection film is a semiconductor device manufacturing method using a shallow trench isolation, characterized in that formed to about 400 ~ 700Å. The method of claim 6, The method of manufacturing a semiconductor device using shallow trench isolation, characterized in that the photosensitive film is formed to about 4000 ~ 5000Å.