JPH02250354A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance a performance and a yield of a semiconductor device by a method wherein a high-melting-point metal film is treated with a plasma in an atmosphere containing atoms of at least one kind selected from a group composed of nitrogen, carbon and boron and, after that, a second wiring layer is formed so as to come into contact with a plasma-treated surface. CONSTITUTION:A high-melting-point metal layer 20 is formed at least in parts exposed from connection holes 17 to 19. After that, the high-melting-point metal layer 20 is treated with a plasma in an atmosphere containing atoms of at least one kind selected from a group composed of nitrogen, carbon and boron; a plasma-treated layer 21 is formed on its surface. A wiring metal is applied onto an insulating film 16 by a sputtering method or the like; it is patterned, e.g. by a photolithographic method using a reactive ion etching operation; a wiring layer 22 connected to the layer 21 via the individual connection holes 17 to 19 is formed. Thereby, it is possible to effectively prevent a mutual diffu sion and a reaction between wiring parts and a substrate; a performance of a semiconductor device can be enhanced; a degree of designing freedom can be increased; a production yield can be enhanced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for manufacturing a semiconductor device, and particularly relates to a method for manufacturing a semiconductor device, and particularly relates to a method for manufacturing a semiconductor device, and in particular, a method for manufacturing a semiconductor device. The present invention relates to a method of manufacturing a semiconductor device, including a step of connecting a second wiring layer through a contact hole formed in the semiconductor device.

(Prior Art) Conventionally, when forming a semiconductor device on a silicon substrate, for example, a silicon substrate or a silicon wiring and an aluminum wiring are connected through a connection hole. In that case, it is known that if silicon and aluminum are left directly connected, they will react with each other during a post-heat treatment process such as annealing, which will adversely affect the element region within the substrate. In order to prevent such unfavorable interaction between silicon and aluminum, the following measures have been taken in the past.

(1) Silicon is preliminarily contained in aluminum at a supersaturated concentration that reaches the temperature of the post-heat treatment step.

(2) A barrier metal, for example, a refractory metal film several thousand angstroms thick, is interposed as a diffusion/reaction barrier layer at the interface between silicon and aluminum.

(Problem to be Solved by the Invention) The method (1) above has the problem that silicon is deposited in the wiring or in the connection hole after post-heat treatment because the wiring aluminum contains excessive silicon. . Such silicon precipitation significantly shortens the lifespan of interconnects and significantly deteriorates contact characteristics, resulting in lower production yields of semiconductor devices and restrictions on device design.

Method 1 (2) basically prevents mutual diffusion between aluminum and silicon. However, there is a close relationship between the barrier metal film thickness and its effectiveness.
Even though it is a barrier metal, unless it has a sufficient film thickness, it will not be possible to prevent the reaction between aluminum and silicon, and furthermore, the barrier metal may have defects such as pinholes.

Diffusion occurs through these defects, reducing the performance of the barrier metal.

As described above, conventional barrier metals require considerable thickness (eg, several thousand angstroms or more), which contributes to increased manufacturing costs and manufacturing times of semiconductor devices.

Therefore, the main object of the present invention is to provide a method of manufacturing a semiconductor device in which the above-mentioned conventional drawbacks are reduced or eliminated.

[Structure of the invention]

(Means for Solving Problems) In order to solve the above-mentioned conventional problems, the present invention provides a method in which the surface of a barrier metal (high melting point metal) is made of at least one material selected from the group consisting of nitrogen, carbon, and boron. A wiring layer is formed after plasma processing in an atmosphere containing one type of atoms.

That is, according to the present invention, there is provided a method for manufacturing a semiconductor device including a step of connecting a second wiring layer to a semiconductor substrate or a wiring layer formed on the semiconductor substrate through a connection hole formed in an insulating film. , a high melting point metal film is formed on at least the connection surface exposed in the connection hole of the semiconductor substrate or a wiring layer formed on the semiconductor substrate, and the high melting point metal film is made of a metal selected from the group consisting of nitrogen, carbon and boron. There is provided a method for manufacturing a semiconductor device, which comprises performing plasma treatment in an atmosphere containing at least one selected type of atom, and then forming the second wiring layer so as to be in contact with the plasma-treated surface. .

The high melting point metal film is preferably formed by selective vapor deposition, and preferred high melting point metals include tungsten, molybdenum, and titanium.

(Function) By treating a high melting point metal in a specific plasma atmosphere according to the present invention, the surface layer of the high melting point metal is converted into a corresponding nitride, carbide and/or boride. These nitrides, carbides, and/or borides dramatically improve the diffusion/reaction barrier effect of the high melting point metal itself.

(Example) This invention will be described below with reference to FIGS. 1A to 1C.
This will be explained in more detail by taking the manufacturing of OSFET as an example.

As shown in FIG. 1A, for example, a -conductive type silicon substrate l
A source region 12 and a drain region 13 are formed in l. A gate electrode 15 made of, for example, polycrystalline silicon is formed on this substrate 11 via a gate insulator 11fi14.

An insulating film 18 such as a silicon dioxide film is formed on the substrate 11 to a thickness of, for example, 5000 Å. after that.

For example, a contact hole is formed to partially expose the source region 12, drain layer 13, and gate electrode 15 by photolithography using reactive ion etching! ? , 18 and 13 are formed in the insulating film 16, respectively.

Thereafter, high melting point metal layer 20 is formed at least in the portions exposed from connection holes 17, 18 and 19. As this high melting point metal, tungsten, titanium, molyftene, hafnium, zirconium, tungsten silicide, titanium silicide, molybdenum silicide, cobalt silicide, nickel silicide, platinum silicide, etc. can be used. Among these, tungsten, titanium and molybdenum are preferred, and these refractory metal layers can be deposited by means such as sputtering. According to a non-selective deposition method such as a sputtering method, the high melting point metal layer is formed on the insulating film 16.
It can also be formed on top. Among the high melting point metals mentioned above, tungsten and molybdenum are grown by selective vapor phase growth.
As shown in Figure 1B, each connection hole 17, 18 and 18
It can be formed only on the exposed silicon surface portions.

Thereafter, the high melting point metal @20 is plasma-treated in an atmosphere containing at least one type of atom selected from the group consisting of nitrogen, carbon, and boron to form a corresponding nitride layer, carbide layer, and (or ) A boride layer (generally shown as plasma treated layer 21 in the figure) is formed. Here, nitrogen gas, ammonia gas, etc. can be used as the nitriding plasma source. As the carbon plasma source, methane gas, ethane gas, carbon dioxide gas, etc. can be used. Further, as a boron plasma source, borane, diporane, etc. can be used.

The above plasma treatment is carried out at room temperature (20°C) to about 500°C.
It can be carried out at low temperatures up to. therefore,
During this plasma treatment, diffusion regions formed in the substrate 11 (for example, source and drain regions 12, !3
) not only does not cause the problem of re-diffusion, but also makes it possible to perform a series of semiconductor device manufacturing processes including the next step in the same reaction apparatus. Since nitriding or the like by heat treatment requires high temperatures, such an effect cannot be obtained.

Furthermore, the nitride, carbide, and boride layers formed by the plasma treatment described in Section 2 can sufficiently exhibit diffusion and reaction barrier effects even if they are as thin as 30 to 40 Å. A thickness of about 300 to 800 Å is sufficient. Therefore, processing becomes easy and it can also contribute to planarization of the wiring layer and insulating layer formed on the substrate.

Note that when the high melting point metal layer 20 is formed by forming tungsten or molybdenum by a selective vapor deposition method and then cooled to room temperature, the selectively formed high melting point metal layer 20 and the connection 1 are formed.
A gap may be formed between the metal plate 7 and the side wall due to contraction of the high melting point metal. - This gap disappears when nitrides, carbides or borides are generated by the plasma treatment described above. This is thought to be because the nitride, carbide, or boride fills pinhole-like defects in the high melting point metal layer 20 and enters the crystal lattice of the high melting point metal, causing the high melting point metal layer to expand.

Thereafter, as shown in FIG. 1C, a wiring metal is deposited on the insulating film 18 by sputtering or the like, and patterned by, for example, a photolithography method using reactive ion etching, to form each connection hole 17.1B and Wiring layers 22 connected to layer 21 via 19 are respectively formed. This wiring metal may be aluminum-based metal (for example, aluminum, aluminum and copper, titanium or silicon (however,
It is also possible to use an alloy with silicon (e is less than the saturation concentration at the eutectic temperature), furthermore, tungsten, molybdenum, metal-rich metal silicide, or the like.

Hereinafter, an embodiment using the method explained along with FIGS. 1A to 1C will be described.

Example 1 This example uses a p-type silicon substrate 11 having source and drain regions 12,13 formed by diffusing arsenic to a depth of 170 OA. Gate insulation film! 4 as a gate electrode, and an insulating film 15.
As a result, silicon dioxide with a thickness of 5000A was formed (
1A), after forming each connection hole 17, 18, 19,
A tungsten layer 20 having a thickness of about 30 OA was formed only on the exposed silicon by selective vapor deposition using tungsten hexafluoride gas (FIG. 1B).

After that, a nitrogen gas atmosphere (N2.Partial pressure: ITo
rr) Tungsten nitride s2 with a thickness of about 3 OA was formed on the tungsten film by generating plasma using a high frequency of 56 MHz and performing a plasma treatment for 60 minutes.
1 was formed (Figure 1B).

An aluminum layer was formed by sputtering using an aluminum target with a purity of 99.999%, and patterned by a photolithographic method using reactive ion etching to form a wiring layer 22.

Example 2 Except for changing the formation of the high melting point metal and the formation of the layer 21,
A semiconductor device was manufactured in the same manner as in Example 1. In this example, titanium as a high melting point metal was formed on the entire surface by sputtering to a thickness of 80 OA, and this was buttered. In addition, this titanium layer was heated at 13.56 MHz in a methane gas atmosphere (methane gas partial pressure: 0, I Torr).
A titanium carbide film was formed on the titanium layer by generating plasma using high frequency waves and performing plasma treatment for 10 minutes.

The semiconductor devices manufactured in Examples 1 and 2 were heated to 450°C for 30 minutes to normalize the aluminum wiring! When the IF heat treatment was performed, no interdiffusion φ reaction between silicon and aluminum in the connection hole was observed.

On the other hand, when plasma nitriding treatment and plasma carbonization treatment were not performed as in Examples 1 and 2, the reaction between silicon and aluminum during the normalizing process was significant, and even if the thickness of the tungsten or titanium layer was 300 OA, Interaction between silicon and aluminum was observed, and the contact characteristics at the interconnection area deteriorated.

[Effects of the Invention] As described above, according to the present invention, mutual diffusion and reaction between the wiring and the substrate can be more effectively prevented than before, and the performance of semiconductor devices can be improved and the freedom of 39 calculations can be improved. It is possible to achieve an increase in efficiency and an improvement in manufacturing yield.

[Brief explanation of drawings]

No.! FIGS. A to tC are cross-sectional views showing one embodiment of the method for manufacturing a semiconductor device according to the present invention in the order of steps. No. 11, 17°, 20, 21...Substrate, No. 15, φ gate electrode, 18, 19-... Connection hole,... High melting point metal layer. ...Plasma treatment layer, 22... Writing line layer Fig. 1A

Claims (2)

[Claims] (1) A method for manufacturing a semiconductor device including a step of connecting a second wiring layer to a semiconductor substrate or a wiring layer formed on the semiconductor substrate through a connection hole formed in an insulating film,
A high melting point metal film is formed on at least the connection surface exposed in the connection hole of the semiconductor substrate or a wiring layer formed on the semiconductor substrate, and the high melting point metal film is selected from the group consisting of nitrogen, carbon, and boron. 1. A method for manufacturing a semiconductor device, characterized in that plasma processing is performed in an atmosphere containing at least one type of atom, and then the second wiring layer is formed so as to be in contact with the plasma-treated surface. (2) The method for manufacturing a semiconductor device according to claim 1, wherein the high melting point metal film is formed by selective vapor deposition.