JP3252397B2 - Wiring formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a wiring which is useful in a manufacturing process of a semiconductor device and the like, and particularly to a method for forming a so-called aluminum spike in a contact portion having a barrier metal made of a titanium (Ti) material layer. The present invention relates to a method for forming a wiring with improved resistance.

[0002]

2. Description of the Related Art As the wiring pattern becomes finer with the increase in the density of semiconductor devices, the junction of the wiring becomes shallower and the contact hole becomes finer. Due to elution of aluminum (Al) or precipitation of silicon (Si) from the electrode wiring material in the contact hole, defects such as breakage or deterioration of the junction or increase in contact resistance are likely to occur. Therefore, alloying reaction between the electrode wiring material and the Si substrate,
It is common to provide a barrier metal between the two for the purpose of preventing the precipitation of the metal. This barrier metal is usually a transition metal or a nitride thereof, a carbide, an oxynitride, a transition metal compound such as a boride, a refractory metal silicide,
It is formed of an alloy or the like. The structure is not limited to a single layer, and a plurality of types of films are often combined. As this kind, Ti is sequentially arranged from the substrate side to the Al-based material layer side.
There is a barrier metal (Ti / TiN-based) having a two-layer structure in which a layer and a TiN layer are stacked.

Since the Ti layer has a high affinity for oxygen, it has a function of reducing a natural oxide film formed on the surface of the impurity diffusion layer, and is a contact material for stabilizing a low-resistance ohmic contact. However, the function alone cannot sufficiently function as a barrier metal. That is, even if a Ti layer is solely interposed between the Si substrate and the Al-based material layer, both the reaction between Si and Ti and the reaction between Ti and Al proceed, so that Al penetrates the Si substrate, That is, the occurrence of aluminum spikes cannot be prevented.

On the other hand, the TiN layer is thermodynamically stable to Si and has a higher barrier property than the Ti layer, but has a problem that the contact resistance to p-type Si is particularly high.
In addition, since the crystal grain size when the film is formed by the vacuum thin film forming technique is about 200 ° and has a columnar structure, Al diffuses at the grain boundary after the heat treatment to sufficiently remove aluminum spikes. It cannot be prevented. Further, when formed directly on a Si substrate, oxygen taken in as an impurity in the film tends to segregate at the interface with the Si substrate,
It is difficult to always form a low-resistance ohmic contact by itself.

Therefore, a Ti layer is first formed on a Si substrate, and then a TiN layer is laminated.

[0006]

In order to further improve the barrier properties, a two-layer barrier metal (Ti / TiON) has been proposed in which a TiON layer is formed by introducing oxygen during the formation of a TiN layer. This is to prevent the diffusion of Al at the grain boundary by segregating oxygen at the grain boundary of TiN.

[0007]

When the TiON layer is used, although the barrier property is improved, the following problems newly arise.

The first problem is that the sheet resistance increases more than three times as compared with the TiN layer containing no oxygen.

A second problem is that after-corrosion is more likely to occur than in the case where a TiN layer is used. As a gas for dry etching of the Al-based material layer and the barrier metal, a chlorine-based gas such as BCl ₃ is usually used, and this gas reacts with oxygen in the TiON layer to form Cl 2 gas.
_{This is because 2} is generated. After-corrosion
Besides these chemical factors, there are also structural factors. That is, the TiON layer has a rough surface morphology and a TiN layer.
This is because the wettability with the Al-based material layer is inferior to that of the Al-based material layer, so that it is easy to provide a place for retaining residual chlorine at the interface with the Al-based material layer.

[0010] The third problem is the deterioration of step coverage (step coverage). In a highly integrated semiconductor device, the diameter of a connection hole formed in an interlayer insulating film has been reduced in order to connect a lower wiring and an upper wiring, and the aspect ratio has become more than one. However, the TiON layer has a rough surface morphology as described above, and is poor in wettability and reactivity with an Al-based material. Is easy to occur.

As described above, in the conventional technology, low resistance,
It is difficult to form a contact that simultaneously satisfies the requirements of high barrier properties and excellent step coverage. Accordingly, an object of the present invention is to provide a wiring forming method that can simultaneously satisfy these requirements.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a semiconductor device having a contact hole formed in an insulating film on a substrate.
The titanium layer, titanium nitride layer, and aluminum-based material layer
A step of forming a titanium layer on a lower layer side of the connection hole, a step of forming a titanium nitride layer on an upper layer side of the titanium layer, Forming an amorphous titanium nitride layer by ion-implanting nitrogen into the titanium nitride layer formed on the bottom and side walls; and forming an aluminum-based material layer to fill at least the connection hole. And a step of performing

[0013]

[Function] By forming an amorphous titanium nitride layer by ion-implanting nitrogen into the titanium nitride layer, the barrier property against aluminum spikes is improved, and the surface morphology is degraded and after-corrosion is promoted. Etc. are suppressed.

The desired amorphization of the thin titanium nitride layer can be achieved with good controllability by appropriately setting conditions such as implantation energy and dose amount.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

This embodiment is an example in which the present invention is applied to the formation of a contact in the source / drain region of a MOS transistor, and is made amorphous by ion-implanting N ₂ into a TiN layer. This process will be described with reference to FIGS.

First, as shown in FIG.
A field oxide film 2 is formed on a substrate 1 by, for example, a LOCOS method, and a gate electrode 4 made of DOPOS or the like is formed in a device formation region defined by the field oxide film 2 via a gate oxide film 3 made of silicon oxide or the like. I do.

Next, after the first ion implantation for forming the source / drain regions 5 using the gate electrode 4 as a mask, sidewalls 6 made of silicon oxide or the like are formed by a conventional method such as CVD and RIE. To form Thereafter, a second ion implantation for increasing the impurity concentration in a part of the source / drain region 5 is performed using the gate electrode 4 and the sidewall 6 as a mask, and the LD
Form a D structure. Further, for example, CV
D to form an interlayer insulating film 7 by depositing silicon oxide or the like, and then pattern the interlayer insulating film 7 to
A contact hole 8 facing the drain region 5 is opened.

Subsequently, a barrier metal having a two-layer structure of Ti / TiN system is formed. First, the lower Ti layer 9 has an Ar flow rate of 50 SCCM and a gas pressure of 0.47 Pa as an example.
(3.5 mTorr), DC sputter power 4 kW,
By sputtering at a substrate temperature of 300 ° C., a thickness of about 300 · was formed. In addition, T
As an example, the iN layer 10 has a N ₂ flow rate of 50 SCCM, a gas pressure of 0.47 Pa (3.5 mTorr), and DC sputtering.
Reactive sputtering is performed at a power of 6 kW and a substrate temperature of 300 ° C. to form a film having a thickness of about 700 °.

Next, as an example, the implantation energy is 50 ke.
V, N under the condition of dose amount 5 × 10 ¹⁵ atom / cm ²
The ion implantation of No. ₂ was performed on the entire surface of the substrate, and as shown in FIG. 1B, the TiN layer 10 was changed to an amorphous TiN layer 9a.

Further, Al-1% by sputtering
A Si layer is formed to a thickness of about 4000 °. The sputtering conditions are, for example, an Ar flow rate of 100 SCCM, a gas pressure of 0.47 Pa (3.5 mTorr), a DC sputtering power of 22.7 kW, and a substrate temperature of 200 ° C. At this time, the entire surface of the base is covered with the Al-1% Si layer, and the inside of the contact hole 8 can be evenly buried without generating voids.

Finally, dry etching is performed using a chlorine-based mixed gas such as a BCl ₃ / Cl ₂ system,
The Al-1% Si layer, the amorphized TiN layer 10a, and the Ti layer 9 were simultaneously patterned to form an Al-based wiring pattern 11 as shown in FIG. After the completion of the dry etching, remarkable after-corrosion was not observed as in the case of using the TiON layer on the upper layer side of the barrier metal having the two-layer structure.

In order to confirm the barrier property of the amorphized TiN layer 10a in the MOS transistor formed through the above-described steps, the MO was held at a predetermined temperature for 30 minutes.
The junction leak current was measured by applying a voltage of -5.5 V to the gate electrode of the S transistor. As a result, the MOS transistor did not show any increase in junction leak current even after annealing at 600 ° C. This means that 60
Even at 0 ° C., the amorphized TiN layer 10a functions as an effective barrier metal without reacting with Al, which means that penetration of Al into the source / drain regions 5 is prevented.

By the way, the present invention is not limited to the above-mentioned embodiment. For example, the ion implantation for amorphizing the TiN layer 10 is not performed on the entire surface of the substrate, but by using a suitable mask, for example. It may be performed only in the vicinity of the contact portion via the contact.

[0025]

As described above, by applying the method of the present invention, it is possible to form a contact having low resistance, excellent barrier properties and excellent step coverage. Therefore, the present invention is suitable for manufacturing a semiconductor device that requires high integration and high performance based on a fine design rule.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example in which the present invention is applied to the manufacture of a MOS transistor in the order of steps,
(A) is a state in which a two-layered barrier metal composed of a Ti layer and a TiN layer is laminated by covering an interlayer insulating film in which a contact hole is formed, and (b) is a state in which the TiN layer is amorphous by ion implantation. (C) shows a state in which an Al-based wiring pattern is formed.

[Explanation of symbols]

Reference Signs List 1 Si substrate, 4 Gate electrode, 5 Source / drain region, 7 Interlayer insulating film, 8 Contact hole, 9 Ti layer, 10 TiN layer, 10a Amorphized TiN layer, 11 Al-based wiring pattern

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3205 H01L 21/3213 H01L 21/768

Claims (1)

(57) [Claims] 1. A connection hole formed in an insulating film on a substrate.
The titanium layer, titanium nitride layer, and aluminum-based material layer
In the method for forming are sequentially formed wire, forming a titanium layer on the lower layer side of the connection hole, forming an upper layer on the titanium nitride layer of the titanium layer, the bottom of at least the connection hole and the side wall portions Forming an amorphous titanium nitride layer by ion-implanting nitrogen into the titanium nitride layer formed in the above, and forming an aluminum-based material layer so as to fill at least the connection holes. A method for forming a wiring, comprising: