KR20080024371A - Method of forming contact plug in a semiconductor device - Google Patents

Abstract

A method for forming a contact plug in a semiconductor device is provided to prevent overhang occurring on the top of passivation layer, generating seams by forming an enlarged upper width of a drain contact hole during the formation of the drain contact hole. A method for forming a drain contact plug in a semiconductor device comprises the steps of: forming an etching stopper(202), an insulator film(204), and a hard mask on a semiconductor substrate(200); sequentially etching the hard mask, insulator film, and etching stopper to form a drain contact hole(210); forming a passivation layer on a lower side of the drain contact hole; removing a part of the insulator film overhanging the passivation layer, so as to enlarge an upper side of the drain contact hole; removing the passivation layer within the drain contact hole; and forming a contact plug(213) within the drain contact hole.

Description

Method of forming contact plug in a semiconductor device

1A to 1D are cross-sectional views illustrating a method for forming a contact plug of a semiconductor device according to the prior art.

2A to 2E are cross-sectional views illustrating a method for forming a contact plug of a semiconductor device according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

200: semiconductor substrate 202: etching prevention film

204: First interlayer insulating film 206: Second interlayer insulating film

208: poly hard mask 210: drain contact hole

212: antireflection film 214: wet barrier nitride film

216: Drain Contact Poly Plug

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a contact plug of a semiconductor device, and in particular, by forming a wider upper width of a drain contact hole in a drain contact hole forming process, generation of a seam when forming a drain contact plug is suppressed. The present invention relates to a method for forming a contact plug of a semiconductor device capable of manufacturing a more stable device.

1A to 1E are cross-sectional views illustrating a method for forming a contact plug of a semiconductor device according to the prior art.

Referring to FIG. 1A, an etch stop layer 102 and a first interlayer insulating layer 104 are formed on a semiconductor substrate 100 on which a predetermined pattern such as an isolation layer (not shown), a gate (not shown), a gate spacer (not shown) is formed. ) Are formed sequentially. The first interlayer insulating layer 104 and the etch stop layer 102 are etched to form a source contact hole (not shown), and the polysilicon is embedded in the formed source contact hole (not shown), and then CMP (Chemical Mechanical Polishing) The process forms a source contact plug (not shown). A second interlayer insulating film 105, an amorphous carbon mask 106, a SiON 107 and a bottom anti-reflective coating 108 are sequentially formed on the entire structure, and then a photoresist is formed thereon. 109 is formed.

Referring to FIG. 1B, after the lower antireflection film 108, the SiON 107, and the amorphous carbon mask 106 are patterned using the photoresist 109, the photoresist 109 and the lower antireflection film 108 are patterned. And SiON 107 is removed. The drain contact hole 110 is formed by sequentially etching the second interlayer insulating film 105 and the first interlayer insulating film 104 using the patterned amorphous carbon mask 106. The etching process for forming the drain contact hole 110 is terminated by exposing the etch stop layer 102 formed below. In this case, a bowing profile is formed in the middle portion of the drain contact hole 110. That is, since the upper width is formed to be narrower than the width of the middle portion, an overhang may occur in a subsequent contact hole filling process, thereby causing seam.

Referring to FIG. 1C, after removing the amorphous carbon mask 106, a polysilicon layer 112 is formed on the entire structure including the drain contact hole 110 to completely fill the drain contact hole 110 with polysilicon. do. At this time, the seam 114 is generated inside the drain contact hole 110 due to the bowing profile of the drain contact hole 110. Thereafter, a contact plug is formed by removing the polysilicon layer 112 on the second interlayer insulating layer 105 by a chemical mechanical polishing (CMP) process or an etch back process. At this time, a part of the shim 114 formed inside the contact plug is exposed to the outside.

Referring to FIG. 1D, the barrier metal layer 130 is formed on the entire structure by using titanium / titanium nitride (Ti / TiN). At this time, as shown in the enlarged view of the seam 114, since the formation of the barrier metal layer 130 at the seam 114 generation site is incomplete, the barrier metal layer 130 is not formed at the place where the seam 114 is repaid. Part occurs. As a result, in a subsequent process of forming tungsten using a fluorine-based reaction gas to form a conductive material layer (not shown), the reaction gas introduced into the shim 114 reacts with the contact plug. Therefore, there is a problem in that the contact plug is lost, which adversely affects the performance of the device and reduces the reliability of the device.

Disclosure of Invention An object of the present invention devised to solve the above problems is to provide a method for forming a contact plug of a semiconductor device capable of manufacturing a more stable element by suppressing generation of seams when embedding a polysilicon material in a drain contact plug. There is.

In an embodiment, a method of forming a contact plug in a semiconductor device may include forming an etch stop layer, an insulating layer, and a hard mask on a semiconductor substrate, and sequentially etching the hard mask, insulating layer, and an etch stop layer to form a contact hole. Forming a protective film under the contact hole, removing a portion of the insulating film protruding higher than the protective film so that an upper portion of the contact hole is widened, and removing the protective film inside the contact hole. And forming a contact plug inside the contact hole.

A portion of the insulating film may be removed by the sputtering process.

The sputtering process may use argon gas or a gas mixed with argon and oxygen.

Before performing the sputtering process, a wet etching process may be performed.

The protective film may be formed as an antireflection film.

The anti-reflection film may be a conformal type or a planar type.

The forming of the passivation layer under the contact hole may include forming the passivation layer with a thickness of 300 mV to 1500 mV over the entire structure including the contact hole and selectively removing the passivation layer inside the contact hole. have.

When selectively removing the protective layer inside the contact hole, a single oxygen gas may be used, or oxygen and argon or oxygen and helium or a mixed gas of oxygen and nitrogen may be selected and used.

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

2A through 2E are cross-sectional views of devices sequentially illustrated to explain a method for forming a contact plug of a semiconductor device according to an embodiment of the present invention.

As shown in FIG. 2A, an etch stop layer 202 and a first interlayer insulating layer are formed on a semiconductor substrate 200 on which a predetermined pattern, such as an isolation layer (not shown), a gate (not shown), a gate spacer (not shown), etc., is formed. 204 are formed sequentially. The first interlayer insulating layer 204 and the etch stop layer 202 are etched to form a source contact hole (not shown). After embedding polysilicon into the formed source contact hole (not shown), a source contact plug (not shown) is formed through a CMP process.

Subsequently, a second interlayer insulating film 205, an amorphous carbon mask (not shown), a SiON (not shown), and a lower antireflection film (not shown) are sequentially formed on the entire structure, and then a photoresist (not shown) is formed thereon. To form. After patterning the lower anti-reflection film (not shown), SiON (not shown) and amorphous carbon mask (not shown) using a photo resist (not shown), the photo resist (not shown), the lower anti-reflection film (not shown) And SiON (not shown). A drain contact hole 210 is formed by sequentially etching the second interlayer insulating layer 205, the first interlayer insulating layer 204, and the etch stop layer 202 using a patterned amorphous carbon mask (not shown). The etching process for forming the drain contact hole 210 is terminated by exposing the etch stop layer 202 formed at the bottom. At this time, a boeing profile is formed in the middle portion of the drain contact hole 210.

In the above, the second interlayer insulating film 206 may be formed of an HDP oxide film or a PE-TEOS film. An amorphous carbon mask (not shown) may be formed to a thickness of 1500 kPa to 4000 kPa. The thickness of SiON (not shown) may be formed to a thickness of 200 kPa to 500 kPa.

Referring to FIG. 2B, after removing the etch stop layer 202 under the drain contact hole 210, the passivation layer 211 may be formed on the upper surface of the entire structure to have a thickness of 300 μm to 1500 μm. The drain contact hole 210 is then buried in the protective film 211. The protective film 211 may be formed using a conventional anti reflective coating (ARC), and may be either a conformal type antireflection film or a planar type antireflection film. The passivation layer 211 prevents the reaction gas from directly contacting the semiconductor substrate 200 under the drain contact hole 210 in a subsequent sputtering process.

Subsequently, the protective film 211 in the protective film 211 and the drain contact hole 210 on the upper surface of the entire structure using a single oxygen gas or a mixed gas in which oxygen and argon, oxygen and helium, oxygen and nitrogen are mixed. Remove part of). As a result, the upper portion of the interlayer insulating layer between the upper portion of the drain contact hole 210 and the drain contact hole 210 is partially exposed.

In the above, the boeing profile generated during the above-described drain contact hole 210 formation process should be exposed by removing the protective film 211. In this case, the thickness of the protective film 211 removed in the drain contact hole 210 may be appropriately changed in consideration of the height of the boeing profile.

Referring to FIG. 2C, an upper portion of the second interlayer insulating layer 205 exposed between the drain contact holes 210 is partially etched by performing an argon sputtering process. Accordingly, the upper width of the drain contact hole 210 may be wider, and at the same time, the upper edge of the drain contact hole 210 may be rounded. At this time, the argon sputtering process may use argon gas or a gas mixed with argon and oxygen.

 Meanwhile, the wet etching process may be performed first before the sputtering process. When the wet etching process is performed, the upper portion of the second interlayer insulating layer 205 between the drain contact holes 210 is preliminarily etched, so that the upper portion of the second interlayer insulating layer 205 may be more easily etched in a subsequent sputtering process. have. The wet etching may use a BOE solution of 100: 1 to 300: 1.

Referring to FIG. 2D, all of the passivation layer 211 in the drain contact hole 210 are removed and the polysilicon layer 212 is formed on the entire structure. At this time, since the upper width of the second interlayer insulating layer 205 between the drain contact holes 210 is wider and the corners of the upper part of the drain contact hole 210 are rounded, the drain contact hole (the polysilicon layer 212) is formed. When filling 210, the occurrence of shims can be suppressed as much as possible.

Referring to FIG. 2E, the contact plug 213 is formed by removing the polysilicon layer on the second interlayer insulating layer 205 by a chemical mechanical polishing (CMP) process or an etch back process.

Thereafter, an etch stop layer 230 and an interlayer insulating layer 231 are formed on the entire structure, and then a patterning process is performed to etch predetermined regions of the interlayer insulating layer 231 and the etch stop layer 230 to form a wiring region. A barrier metal layer 232 is formed on the entire structure, a tungsten layer or an aluminum layer is formed to fill the wiring region, and then a CMP process is performed to form the wiring 233 on the contact plug 231.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, according to the present invention, after forming the drain contact hole, the width of the upper part of the interlayer insulating film between the drain contact holes and the corners are rounded, thereby deliberation caused by the bowing profile in the contact plug in the subsequent contact plug forming process. Formation can be suppressed. As a result, a more stable device can be manufactured.

Claims (8)

Forming an etch stop layer, an insulating layer, and a hard mask on the semiconductor substrate; Forming a contact hole by sequentially etching the hard mask, the insulating film, and the etch stop layer; Forming a passivation layer under the contact hole; Removing a portion of the insulating layer protruding higher than the passivation layer so that an upper portion of the contact hole is widened; Removing the protective layer inside the contact hole; And And forming a contact plug in the contact hole. The method of claim 1, A method of forming a contact plug in a semiconductor device by performing a sputtering process to remove a portion of the insulating film. The method of claim 2, The sputtering process is a contact plug forming method of a semiconductor device using argon gas or a gas mixed with argon and oxygen. The method of claim 2, And a wet etching process prior to the sputtering process. The method of claim 1, And forming the protective film as an anti-reflection film. The method of claim 5, And the anti-reflection film is a conformal type or a planar type. The method of claim 1, Forming the passivation layer below the contact hole, Forming the protective film on the entire structure including the contact hole at a thickness of 300 mW to 1500 mW; And selectively removing the passivation layer in the contact hole. The method of claim 7, wherein The method of claim 1, wherein a single oxygen gas is used to selectively remove the passivation layer inside the contact hole, or a mixed gas including oxygen and argon or oxygen and helium or oxygen and nitrogen is used.

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