KR0154767B1 - Fabrication method of semiconductor device - Google Patents

Abstract

The present invention is a method of forming an electrode wiring using a contact window and a barrier metal for electrically connecting a semiconductor device in which a pad oxide film, a field oxide film, a gate electrode, and an active region are formed on the silicon substrate to the outside. First, remove the pad oxide layer over the active region except the bottom of the gate electrode, and deposit a barrier metal layer with one or more metals from a group of metals consisting of titanium, tungsten, molybdenum, platinum, lead, tantalum, cobalt, chromium, and nickel on the front surface. do. After depositing the metal nitride film on the barrier metal layer, the metal nitride film and the barrier metal layer are photo-etched to leave only the portion located above the active region. An insulating oxide film and an interlayer insulating film are sequentially stacked and etched on the entire surface to form a contact window, and then an electrode wiring directly contacting the metal nitride film is formed through the contact window. In this way, the contact resistance is reduced by increasing the contact area between the barrier metal and the diffusion region, and the damage of the diffusion region due to plasma etching during formation of the contact window can be prevented by forming the barrier metal layer on the active region in advance.

Description

Manufacturing Method of Semiconductor Device

1 to 4 are cross-sectional views showing a method for forming electrode wirings of a conventional semiconductor device, in accordance with a manufacturing process sequence.

5 to 8 are sectional views of the manufacturing process of a preferred embodiment showing a method for forming electrode wirings of a semiconductor device according to the present invention.

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a barrier metal layer formed in a contact portion in a contact window for electrical connection with an adjacent semiconductor element.

In recent years, as semiconductor devices become more integrated, design dimensions become submicron or half micron, resulting in a decrease in the size of contact windows and an increase in aspect ratio. Therefore, when the metal wiring film is formed in the contact window having a large step, not only silicon precipitates are generated inside the contact window, but also the contact resistance increases and leakage current increases. Most semiconductor devices are made using silicon wafers or substrates to make doped regions, that is, regions where impurities are diffused or implanted with ions, become electrically conductive, or form PN junctions. Aluminum is commonly used as a metal for forming interconnects or interconnects that electrically connect to or contact an active region in a substrate. In general, in order to increase the integration density and the operating speed of the semiconductor device, the doping region must be made very small and shallow. For example, typical NMOS devices have source and drain doped regions having a depth of 0.3 μm to 0.3.5 μm and a channel length of 1 μm to 2 μm.

In order to shorten the channel length to, for example, about 0.7 µm to 0.8 µm, the threshold voltage is remarkably reduced, so the depth of the source and drain regions must be formed to 0.1 µm or less.

However, this causes a problem in that aluminum is abnormally diffused into the silicon substrate through crystal defects of silicon, thereby causing a problem in that the pn junction formed between the doped region and the silicon substrate is destroyed. Such anomalous diffusion of aluminum easily occurs even in a relatively low temperature process, which is often used in the manufacture of a semiconductor device, and as a result, it is difficult to obtain a reliable semiconductor device having a shallow doping region on a silicon substrate.

Therefore, in order to suppress the abnormal diffusion of aluminum into the silicon substrate, it is proposed to insert a barrier metal layer made of tungsten, molybdenum, titanium or the like between the silicon substrate and the aluminum electrode or the metal wiring layer.

Conventionally, a titanium metal and a titanium nitride film are formed by a sputtering method as a barrier metal for preventing silicon from depositing on the contact window. In this case, the electrical characteristics of the semiconductor device are degraded due to the interface instability between the titanium film and the silicon. In addition, it is difficult to reproduce the titanium nitride film having a stable composition ratio, and a large amount of particles are generated to deteriorate the film quality and cause poor contact of the semiconductor device.

1 to 4 are cross-sectional views showing a conventional method for forming electrode wirings in a semiconductor device according to manufacturing fixing procedures. A method of forming electrode wirings using a conventional barrier metal layer will be described with reference to the drawings.

First, referring to FIG. 1, a pad oxide film 101 of about several hundred microseconds is formed on a silicon substrate 100 according to a conventional semiconductor device manufacturing method, and then a field oxide film 102 is formed, followed by polysilicon. And a gate electrode 103 made of silicide and a spacer 104 surrounding the sidewalls of the gate electrode 103 in sequence, and then an active region 105 of a source / drain is formed.

Next, referring to FIG. 2, an insulating oxide film 106 is deposited on the entire upper surface of the semiconductor substrate in the above state, and then a photoresist film (not shown) is applied, and then the contact area is determined by a photographic process. A photoresist pattern is formed, and a contact portion 107 is formed by etching a predetermined portion of the insulating oxide film 106 above the active region using the photoresist pattern.

Next, referring to FIG. 3, after removing the thin pad oxide film 101 formed on the active region 105 in the contact window 107 using an aqueous hydrofluoric acid (HF) solution, each of several hundreds of titanium (Ti) ) And titanium nitride (TiN) barrier metals are sequentially deposited in an in-suit method, and then heat-treated at a temperature of 400 or more to stabilize the barrier metal layer 108, and then the barrier metal layer 108 An aluminum metal layer 109 is formed thereon.

Subsequently, referring to FIG. 4, a photoresist film is coated on the metal layer 109, and then a photoresist pattern (not shown) for forming metal wirings is formed by a photographic process, and the photoresist pattern is used. The metal layer 109 and the barrier metal layer 108 are sequentially etched to form electrode wiring.

According to the conventional metal wiring forming method as described above, in order to prevent the spike phenomenon of the aluminum-based metal layer and silicon or the silicon nodule at the contact portion of the active region and the electrode wiring, A barrier metal of titanium nitride is needed under the metal layer.

However, since titanium nitride has a very high specific resistance, it is required to form a titanium film under the titanium nitride film in order to reduce the contact resistance. As described above, although a titanium film having a constant thickness must be secured at the contact portion, it is very difficult to deposit a barrier metal having a uniform thickness in the minute contact portion as the width of the contact portion is reduced to less than submicron due to the recent high integration of semiconductor devices. Under conventional process conditions, the thickness of the barrier metal is 1500Å or less, and the titanium nitride is about 1000Å. As the design dimension of the semiconductor device is refined, for example, when the barrier metal is deposited on the contact portion through a contact window having a width of 0.6 μm or less, The contact resistance can be increased up to several,. This is because the step coverage of the heat-resistant metal is poor due to the increase in the aspect ratio due to the miniaturization of the design dimension, and thus the titanium film is not uniformly deposited in the contact window. Is a major obstacle to the high integration of semiconductor devices.

In addition, in the process of patterning the photoresist on the insulating oxide film and etching the insulating oxide to form a contact window on the insulating oxide film, an active region such as a source or a drain is etched by plasma etching and thus structurally damaged. There is a problem that causes a defect.

Accordingly, an object of the present invention has been made in view of the problems of the prior art, and a method of forming an electrode wiring using a barrier metal layer having a uniform thickness between the active region and the electrode wiring regardless of an increase in the aspect ratio of the contact window. To provide.

The electrode wiring forming method of the preferred embodiment of the present invention for achieving the above object comprises a contact window for electrically connecting the semiconductor device, the pad oxide film, the field oxide film, the gate electrode and the active region formed on the silicon substrate with the outside; A method of forming an electrode wiring using a barrier metal, the method comprising: removing the pad oxide layer on an upper portion of an active region excluding the lower portion of the gate electrode, titanium, tungsten, molybdenum, platinum, lead, tantalum, cobalt, Depositing a barrier metal layer with one or more metals from a group of chromium and nickel, depositing a metal nitride film on the barrier metal layer, and photoetching the metal nitride film and the barrier metal layer to leave only the portion located above the active region. Step, insulating oxide film and interlayer insulation on the entire surface of the resultant A step of sequentially stacked, forming a contact window, and then etching the interlayer insulating film and an insulating oxide film, and forming a wiring electrode in direct contact with the metal nitride film via the contact window.

According to this configuration, in the conventional electrode wiring, the contact area between the active region and the metal wiring is almost limited to the width of the contact window. However, in the present invention, the contact area between the barrier metal and the diffusion region becomes large, which greatly reduces the contact resistance. In addition, since the barrier metal layer is previously formed on the active region of the portion where the contact portion is to be formed, damage of the diffusion region due to plasma etching is prevented when forming the contact window.

Hereinafter, a method of forming electrode wirings of a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

5 to 8 are sectional views of the manufacturing process of the preferred embodiment of the method for forming the electrode wiring of the semiconductor device according to the present invention.

First, referring to FIG. 5, the cross-sectional state of the semiconductor device after the active region is formed by a conventional semiconductor device manufacturing method is shown. The silicon substrate 200, the pad oxide film 201, the field oxide film 202, The gate electrode 203 is formed of a gate electrode sidewall spacer 204 and a diffusion region 205.

Referring to FIG. 6, the pad oxide film 201 having a thickness of about 200 μs on the active region 205 is removed by wet etching with an aqueous hydrofluoric acid (HF) solution, and then the titanium film 206 having a thickness of about several hundred μs is formed. Titanium nitride 207 having a thickness of about 1000 μs is continuously deposited by in-shoot sputtering. In this case, as a method of forming the barrier metal, for example, one metal may be selected from a group of metals consisting of titanium, tungsten, molybdenum, platinum, lead, tantalum, cobalt, chromium, and nickel to form a single film, or the group The metal may be formed using an alloy film composed of at least two metals, or may be formed as a multilayer film laminated by combining a plurality of the above metals.

In the case of depositing barrier metal layers such as titanium in this manner, a heat treatment process for causing a silicide reaction is unnecessary. Then, a photosensitive film is applied to the entire surface of the resultant so that a barrier metal pattern is formed only on an active region such as a source, a drain, or an emitter, a base, and a collector or a gate, and the like, and then the barrier metal pattern is defined. After the photoresist pattern 208 is formed, the barrier metal layers 207 and 206 are sequentially etched by wet etching using hydrogen peroxide or a dry method using plasma using the photoresist pattern as an etching mask. At this time, the formed barrier metal pattern should cover the whole or part of the active region and the area of the barrier metal pattern should be larger than the contact area of the contact window.

Subsequently, referring to FIG. 7, the insulating oxide film 209 having a thickness of about several thousand micrometers is deposited on the entire surface of the resultant by chemical vapor deposition, and then heat-treated for densification of the insulating oxide layer, and then again, several thousand micrometers. A BPSG film 210 having a thickness is deposited by chemical vapor deposition, and the BPSG film 210 is reflowed through a heat treatment process. At this time, some titanium may be silicided by reacting with silicon through the heat treatment process for densification and reflow. While the specific resistance of titanium is 40 μΩ · cm to 50 μΩ · cm, the specific resistance of titanium silicide is 13 μΩ · cm to 16 μΩ · cm, and the contact resistance can be greatly reduced due to the formation of titanium silicide. Subsequently, after the photoresist film (not shown) is applied to the entire surface of the resultant, a photoresist pattern is defined to define a contact window, and then the contact window 211 is formed using the photoresist pattern as an etch stop layer. The contact portion of the bottom of the contact window 211 should be formed within a predetermined portion of the barrier metal pattern described above.

Next, referring to FIG. 8, after depositing an aluminum alloy-based metal on the entire surface of the resultant to form a metal layer (not shown), after applying a photosensitive film on the metal layer, the electrode wiring to the photosensitive film pattern Next, the electrode wiring 212 is formed using the photosensitive film pattern.

Therefore, according to the present invention as described above, after forming the titanium film and the titanium nitride film formed in the bottom of the contact window in advance, the insulating film is deposited to form a contact window, and the electrode wiring is formed to always ensure a barrier metal layer of a constant thickness. As a result, the contact resistance can be kept constant irrespective of the increase in the aspect ratio of the contact window, and it is possible to prevent the uniformity of the barrier metal thickness and the deterioration of the step coating ability, and also to prevent the titanium from the interface between the titanium film and the active region. Silicide is formed and the contact area between the barrier metal and the diffusion region is greatly increased, which can greatly reduce the contact resistance.

In the conventional method, after depositing a barrier metal such as titanium, titanium nitride or titanium tungsten, and heat treatment is not performed, aluminum atoms may penetrate through the unstable barrier metal layer, so that the heat treatment is performed after the deposition of the barrier metal layer. However, in the conditions of the present invention, since the structure of the barrier metal can be stabilized through the heat treatment process for the densification after the deposition of the barrier metal layer and the reflow after the deposition of the BPSG film, the barrier metal layer can be stabilized immediately after the deposition of the barrier metal layer. A separate heat treatment process can be omitted.

In addition, in the conventional method, structural defects occur in the silicon substrate due to damage to the upper portion of the diffusion region in the plasma etching process of the insulating oxide film for forming the contact window. Since the barrier metal of titanium and titanium nitride is deposited after removing the solution with an aqueous hydrofluoric acid solution, only the barrier metal on the top of the active region is exposed to the plasma when forming a contact window, thereby preventing damage to the diffusion region or structural defects of the silicon substrate. Can be.

Claims (3)

A method of forming an electrode wiring using a contact window and a barrier metal for electrically connecting a semiconductor device in which a pad oxide film, a field oxide film, a gate electrode and an active region are formed on a silicon substrate to the outside, the lower portion of the gate electrode Removing the pad oxide layer over the active region, except for depositing a barrier metal layer with one or more metals from a group of metals consisting of titanium, tungsten, molybdenum, platinum, lead, tantalum, cobalt, chromium, and nickel on the entire upper surface of the resultant. Depositing a metal nitride film on the barrier metal layer, photoetching the metal nitride film and the barrier metal layer to leave only a portion located above an active region, and sequentially stacking an insulating oxide film and an interlayer insulating film on the entire surface of the resultant product; The interlayer insulating film and the insulating oxide film are sequentially etched and contacted. Forming a window, the method of forming the electrode wiring of a semiconductor device including a step of forming an electrode wiring in direct contact with the metal nitride film via the contact window. The method of claim 1, wherein the barrier metal layer is etched by wet etching using a hydrogen peroxide solution. The method of claim 1, wherein the barrier metal layer is etched by dry etching using plasma.