JP3377896B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device having a self-aligned contact structure using polysilicon and a semiconductor device having the same. The present invention relates to the manufacturing method. 2. Description of the Related Art In a semiconductor device such as an LSI, a technology for contacting a dense pattern of gate electrodes on an element is strongly demanded in order to increase the degree of integration. In a method of forming a contact hole using a resist mask formed by a photolithography technique in an interlayer insulating film, there is a limit in forming a fine contact such as a resolution limit and a margin for alignment. As a technique for contacting a pattern where the gate electrodes are densely formed, a gate electrode and a sidewall insulating film are formed on the side walls thereof, and a patterned polycide is formed on the diffusion layer formed between the gate electrodes and on the sidewalls. And self-aligned contacts (Self-A
(Signed Contact: SAC) is promising. Conventionally, against such contact, to form the wiring layer or a contact plug, such as a polycide (tungsten silicide (WSi _X) / polysilicon). A manufacturing process of a conventional semiconductor device having a self-aligned contact will be described with reference to FIG. First, a gate insulating film 23 is formed on a silicon substrate 21 by a normal MOS transistor forming process, and then a polysilicon film 24 and a tungsten silicide film 25 serving as a gate electrode are laminated, and a silicon oxide film is further formed thereon. 26 are formed, patterned into the shape of a gate electrode, and low-concentration impurity regions 22b of source / drain regions are formed by ion implantation. Thereafter, an insulating film is deposited on the entire surface and etched back to form a sidewall 27 on the side wall of the gate electrode.
A high concentration impurity region 22a of the drain region is formed. Next, an insulating film 28 is deposited at about 500 ° (FIG.
(A)). Next, patterning of the photoresist 29 for forming a contact hole is performed so that a part of the gate electrode is overlapped, and etching of the insulating film 28 is performed by using both wet etching and dry etching. Avoid over-etching (Fig. 3
(B)). This makes it possible to form a contact between fine gate electrode patterns, which is effective in reducing the cell area. Next, a polycide film (polysilicon film 31) is used.
And tungsten silicide film 32) and NSG film 33
Is deposited (FIG. 3C), the polycide film is doped with impurities through the NSG film 33 by ion implantation, and the NSG film 33 on the polycide film is removed by wet etching. Thereafter, the polycide film is etched using the patterned photoresist. The self-aligned contact having the polycide wiring manufactured in this manner has a cross-sectional structure as shown in FIG. When a fine contact hole is used in addition to the polycide wiring structure as described above, a technique of forming a plug using tungsten is used. When this tungsten plug is used, a method of forming a barrier metal composed of a titanium nitride layer / titanium layer between the tungsten plug and the substrate is generally used in order to prevent tungsten from diffusing into the substrate. Also, when aluminum silicide is used in the polycide wiring structure, diffusion of aluminum into the substrate occurs, and it is considered that a similar method is employed. The formation of the barrier metal is promising because a sputtering apparatus equipped with a collimator for performing anisotropic sputtering can sufficiently form a barrier metal layer on the bottom of the contact. However, when a self-aligned contact technique of forming a polycide between gate electrodes of a substrate, forming an interlayer insulating film, and forming a contact hole is used, after the formation of the contact hole, A barrier metal will be formed. In the formation of a barrier metal by a sputtering apparatus equipped with a collimator, the sputter deposition has anisotropy. Therefore, as shown in FIG. It is difficult to form a film, and the coating of the barrier metal 36 is incomplete. As a result, there is a problem that the tungsten 35 diffuses into the silicon substrate 21 through the polysilicon film 31 and junction leakage increases. An object of the present invention is to provide a semiconductor device having a barrier metal layer with good coverage even for a fine contact hole having a step structure in the base. Means for Solving the Problems To solve the above problems
The present invention, over a part of the gate electrode on a plurality of diffusion layers formed in the semiconductor substrate between the gate electrode and on the side wall having a side wall made of an insulating film
A polysilicon film having a step structure by lapping, a barrier metal comprising a silicide film of a transition metal or a refractory metal and a nitride film of the transition metal or a refractory metal on the entire surface of the polysilicon film. film is formed, via the barrier metal film, a semiconductor device the conductive layer and which is formed in the contact hole formed in the interlayer insulating film and the polysilicon film is characterized by being electrically connected It is. In addition, on a diffusion layer formed on a semiconductor substrate between a plurality of gate electrodes having a curved side wall formed of an insulating film and on the side wall ,
From the flat substrate surface to the position where the part of the gate electrode overlaps through the curved part on the sidewall
Patterning a polysilicon film so as to cover a step portion of the above, a step of depositing a transition metal or a high melting point metal on the entire surface of the polysilicon film, and a heat treatment to form the polysilicon film and the transition metal or the high melting point metal. The step of forming a silicide film of the transition metal or high melting point metal, and after removing the unreacted transition metal or high melting point metal,
Heat treating the silicide film in a nitrogen atmosphere to form a nitride film of the transition metal or refractory metal on the surface, a step of forming an interlayer insulating film,
From the flat part on the board surface to the curved part on the sidewall
Form a contact hole in the polysilicon film top over a part
A step of forming, to form a conductive layer in the contact hole, characterized in that a step of electrically connecting the conductive layer and the polysilicon film through the silicide film and nitride film And a method for manufacturing a semiconductor device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments of the present invention. FIG. 1 is a structural sectional view of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a manufacturing process diagram of the semiconductor device shown in FIG. 1 and 2, reference numeral 1 denotes a silicon substrate, 2 denotes an isolation oxide film, 3a denotes a low concentration impurity diffusion layer, 3b denotes a high concentration impurity diffusion layer, 4 denotes a gate insulating film, 5 denotes a gate electrode, and 6 denotes an insulating film. , 6a are sidewalls, 7 is a polysilicon film, 8 is a titanium (Ti) film, 9
Is a titanium silicide film, 10 is a titanium nitride film,
Reference numeral 11 denotes an interlayer insulating film, 12 denotes a tungsten plug, and 13 denotes a wiring. In this embodiment, a titanium film is used, but Ti, Co,
What reacts with polysilicon and forms a silicide layer, such as W, Ni, Mo, Ta, and TiW, is used. As shown in FIG. 1, the semiconductor device according to the present invention has a structure on the high-concentration impurity diffusion layer 3b formed on the semiconductor substrate 1 between the gate electrodes 5 having the side walls 6a made of the insulating film 6 and the side walls. 6a, a polysilicon film 7 having a predetermined shape is formed on the entire surface of the polysilicon film 7; and a silicide film 9 of a transition metal or a high melting point metal and a nitride film 10 of the transition metal or the high melting point metal are formed on the entire surface. A barrier metal layer is formed, and a conductive layer buried in a contact hole formed in the interlayer insulating film 10 is electrically connected to the polysilicon film via the barrier metal layer. Of the barrier metal layers, the nitride film 10 functions as a diffusion barrier, and the silicide film 9 functions to reduce contact resistance. Next, a manufacturing process of the semiconductor device according to one embodiment of the present invention will be described with reference to FIG. First, a silicon substrate 1 is formed by a conventional technique.
A gate electrode 4 made of polysilicon is formed thereon via a gate insulating film 5, and a low concentration impurity diffusion layer 3a is formed by ion implantation using the gate electrode 4 as a mask. Thereafter, an insulating film is formed on the entire surface, sidewalls are formed by etch back, and then the high concentration impurity
To form [0019] Next, the polysilicon film 7 is formed approximately 500 Å, a polysilicon film 7 (which is also applicable in implantation of phosphorus P.) Arsenic As the implantation energy 80 keV, a dose of 6 × 10 ¹⁵ cm ^-2 And then patterning into a predetermined shape. The conditions for implantation into the polysilicon film 7 are optimized in terms of both the suppression of the short Chanel effect and the reduction of the Kelvin resistance. For example, when the dose is increased, the short channel effect tends to deteriorate, and when the dose is decreased, the resistance tends to increase. Next, a thickness of 300
A titanium film 8 having a thickness of about 2000 ° is formed. in this case,
Since it is desirable that the titanium film 8 is entirely a titanium silicide film (a step of removing the unreacted titanium film later can be omitted), the film thickness is desirably about 300 ° (FIG. 2).
(A)). The deposition of the titanium film 8 is preferably performed by a CVD method or a sputtering method that does not use a collimator and has good coverage for the step. Next, using a RTA in a nitrogen atmosphere,
When heating is performed at 0 ° C. to 700 ° C., particularly about 675 ° C. for about 30 seconds, a reaction between the titanium film 8 and the polysilicon film 7 occurs, and a silicide film 9 is formed (FIG. 2B). 70
If the temperature exceeds 0 ° C., silicidation occurs rapidly, which is not preferable. At this time, the unreacted titanium film 7 and the titanium film 7 on the insulating film are removed by etching at about 150 ° C. using a mixed solution of H ₂ SO ₄ + H ₂ O ₂ + H ₂ O. In the step of removing the unreacted titanium film 8, if the unreacted titanium film 8 remains, 850 for lowering the resistance of the later silicide film 9 is performed.
At the time of the heat treatment at about ° C, silicidation is further promoted, so that junction leakage may increase or a short circuit may occur between the gate electrode and the diffusion layer. Through the above steps, the titanium silicide film 9 is exposed on the entire surface of the polysilicon film 7. Next, heat treatment is performed in a nitrogen atmosphere at 800 ° C. or higher, preferably 850 ° C., for 10 seconds to obtain a structure necessary for lowering the resistance of the titanium silicide film 9. A nitride film 10 is formed (FIG. 2C). Next, the interlayer insulating film 11 is formed using a conventional technique.
After forming a contact hole, a tungsten plug 12 is formed, and an aluminum wiring 13 is formed by a normal sputtering method (FIG. 2D). In the present embodiment, the process using the tungsten plug 12 has been described. However, even when a wiring is directly contacted with a polysilicon film serving as a contact pad without using a plug, the wiring and the contact pad are used. It is possible to apply the barrier metal according to the present invention between the polysilicon film. As described above in detail, according to the present invention, it is possible to obtain a barrier metal layer which is well-covered for a contact hole having a step in a base.
Junction leakage due to diffusion of tungsten used for the plug and aluminum used for the wiring can be significantly reduced. Therefore, a semiconductor device having fine contacts can be manufactured, and miniaturization and high integration of LSI can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural sectional view of a semiconductor device according to an embodiment of the present invention. FIG. 2 is a manufacturing process diagram of the semiconductor device according to one embodiment of the present invention; FIG. 3 is a manufacturing process diagram of a conventional semiconductor device. FIG. 4 is a diagram for explaining a conventional problem. [Description of Reference Numerals] 1 silicon substrate 2 isolation oxide film 3a low concentration impurity diffusion layer 3b high concentration impurity diffusion layer 4 gate insulating film 5 gate electrode 6 insulating film 6a sidewall 7 polysilicon film 8 titanium film 9 titanium silicide film 10 Titanium nitride film 11 Interlayer insulating film 12 Tungsten plug 13 Wiring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/28 301 H01L 21/768

Claims (1)

(57) Claims 1. On a diffusion layer formed on a semiconductor substrate between a plurality of gate electrodes having side walls having a curved side surface made of an insulating film, and on the sidewalls Top , flat
From the substrate surface to the position where a part of the gate electrode overlaps through the curved portion on the sidewall.
Patterning a polysilicon film so as to cover the difference portion ; depositing a transition metal or a refractory metal on the entire surface of the polysilicon film; and heat treating the polysilicon film and the transition metal or the refractory metal. Reacting and forming a silicide film of the transition metal or high melting point metal, and removing the unreacted transition metal or high melting point metal, and then heat-treating the silicide film in a nitrogen atmosphere. A step of forming a nitride film of a metal or a refractory metal, a step of forming an interlayer insulating film, and a step of forming a curved portion on a sidewall from a flat portion on a substrate surface.
A contact hole in the polysilicon film upper wide portion
Forming, and forming a conductive layer in the contact hole, and electrically connecting the conductive layer and the polysilicon film via the silicide film and the nitride film. , A method of manufacturing a semiconductor device.