JPH0194657A - Electrode and wiring for semiconductor device - Google Patents

Abstract

PURPOSE:To prevent peeling off of W or Mo and to further prevent increase in contact resistance between an electrode and a diffusion layer by depositing W or Mo on a layer in which metals of groups IVa, Va and VIa, or metals such as Co, Ni or the silicides thereof are nitrided. CONSTITUTION:Tungsten or molybdenum layer 8 is deposited by a chemical vapor deposition (CVD) method on a layer 7 in which metals belonging to groups IVa, Va and VIa in the periodic table, metals such as cobalt or nickel or the silicides thereof are nitrided, and these layers are provided with desired profiles. For example, a p<+>-diffusion layer 3 and n<+>-diffusion layer 4 are formed within an n-well 1 and a p-well 2 which have been arranged on a silicon substrate, and then a silicon oxide containing boron and phosphorus is deposited as an interlayer insulating film 6. Then after forming a contact hole in the insulating film 6, titanium nitride 7 is deposited on the diffusion layers and insulating film 6 within the contact hole. Then after depositing tungsten 8 by the CVD method, a tungsten layer 8 and a titanium nitride layer 7 are formed to provide an electrode and wiring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrode wiring for semiconductor devices, and particularly to electrode wiring suitable for tungsten and molybdenum formed by chemical vapor deposition.

[Prior art] Tungsten and molybdenum electrodes and wiring, which have excellent microfabriability, durable stress migration resistance, and electromigration resistance, have been developed to replace Afl-based wiring, which has been widely used as fine electrodes and wiring for ultra-highly integrated circuits. Attention has been paid. Conventionally, focusing on the feature of good coverage over device steps, attempts have been made to deposit the metal directly on silicon and insulating layers by chemical vapor deposition to form electrodes and wiring. About them, see Extended Abstracts on the 18th (1986 International) Conference on Solid State Devices and Materials A-1.
0-3, (1986) pp. 499-502 (Ex
tended AbStracts of thel
8th (1986 International) C
onference 5olid 5tate D
evices and Materials Tokyo
o.

1986, A-10-3, PP499-502゜198
6 is described in detail.

[Problem that the invention seeks to solve]

In the above conventional technology, it is difficult to deposit tungsten or molybdenum on insulators such as silicon oxide, phosphosilicate glass, or boron-phosphosilicate glass provided in silicon semiconductor devices, and even if tungsten or molybdenum is deposited, the metal has a problem in that it has a weak adhesion to the above-mentioned insulator and peels off during the semiconductor manufacturing process. In addition, in electrodes and wiring made of the metal, during a high-temperature heat treatment process at 800 to 1000°C, these elements easily diffuse into the metal layer from the insulating layer containing phosphorus or boron, and the metal layer contacts the silicon layer. There was a problem in that poor conduction occurred. For example, at the contact part between the tungsten electrode and the p-type diffusion layer,
Phosphorus in the insulating film passes through the Dungesten layer and reaches the p-type diffusion layer.

Insulation resistance between electrode and diffusion layer is 10""δΩ・10-
It was increased to 8Ω・■. Furthermore, in electrodes and wiring made of these metals, the metal and silicon layer easily react with each other due to heat treatment, and the reaction layer peels off due to volumetric contraction accompanying the reaction. The problem was that there was no.

An object of the present invention is to realize a tungsten or molybdenum electrode/wiring that solves the problems of the above technology.

[Means for solving problems]

The above purpose is to deposit N a on the silicon layer and the insulating layer.

After forming in advance a nitride layer of transition metals such as Va, Group VIa, cobalt, and teracel, or their silicon compounds, tungsten or molybdenum is deposited thereon by chemical vapor deposition, and the metal and the nitride are deposited thereon by chemical vapor deposition. By processing the into the desired electrode/wiring shape,
achieved.

[Effect]

The metal nitride layer can be formed by a sputtering method using a sputter target made of a desired nitride.

Further, a metal nitride can be obtained by forming a planarized layer using a specified metal or silicon compound target and then heat-treating it in a nitrogen gas or ammonia gas atmosphere. Furthermore, a film formed by sputtering can be made to have strong adhesion to an insulator by optimizing its formation conditions. Note that since the IVa group metal or its compound has a strong adhesive force to the silicon oxide insulating film, it will not peel off from the insulating layer even if it is formed by chemical vapor deposition. Since tungsten and molybdenum formed by chemical vapor deposition on such a metal nitride film have strong adhesive strength, the problem of peeling off of electrodes and wiring made of these metals, which was a drawback of the prior art, does not occur. Further, in the metal nitride, the diffusion rate of phosphorus and boron is 1 to 4 orders of magnitude lower than that of the metal or silicon compound that constitutes the metal nitride. Therefore, the nitride acts as a barrier to diffusion of phosphorus and boron from the silicon oxide containing phosphorus and boron into the tungsten and molybdenum layers, and can prevent an increase in contact resistance between the electrode and the diffusion layer due to heat treatment.

Furthermore, by providing the metal nitride layer between the tungsten and molybdenum layers and the silicon layer,
The reaction between the metal layer and the silicon layer can also be suppressed by high-temperature heat treatment at 0°C. This shows that even after high-temperature heat treatment of about 1000°C, the metal nitride remains intact with silicon and tungsten.
This is to prevent a rapid reaction with molybdenum.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG.

[Example 1] A p-diffusion layer 3 in which boron is diffused and an n-diffusion layer 4 in which arsenic is diffused are formed in a predetermined region in an n-well 1yP-well 2 provided in a silicon substrate, and then an interlayer insulating film layer 6 is formed. As, boron is 10mo1%.

600nm silicon oxide containing 5mol1% phosphorus
After the deposition, a contact hole with a diameter of 0.5 μm to 1.0 μm was opened in the insulating film using 0-order photolithography technology and dry etching technology. Titanium is sputtered from a titanium target, and titanium nitride 7 is deposited on the diffusion layer in the contact hole and on the insulating film.
00n was deposited.

Next, the above sample was loaded into a reaction vacuum chamber of a chemical vapor deposition apparatus and heated to 300°C, and then tungsten fluoride gas and hydrogen were introduced into the vacuum chamber to cause a chemical reaction between the gases and form a 500 nm layer on the sample. of tungsten 8 was deposited. The tungsten and titanium nitride layers thus formed were processed into electrode/wiring shapes using conventional photolithography and anisotropic dry etching using a reactive gas containing sulfur fluoride as a main component. Finally, in argon gas, 9
A semiconductor device was manufactured by performing heat treatment at 50° C. for 30 minutes. No peeling of tungsten occurred during the heat treatment step of this device fabrication process, and no significant reaction between titanium nitride, tungsten, and the silicon substrate was observed. Further, the contact resistance between the tungsten electrode/wiring and the n+ and p+ diffusion layers both showed good values of 5×10 −7 Ω·d or less, indicating ohmic characteristics. This is due to the barrier effect of titanium nitride against impurity diffusion from the phosphorus- and boron-containing silicon oxide to the tungsten layer. Note that zirconium or hafnium is used instead of the titanium nitride mentioned above.

Similar experiments were conducted with tantalum vanadium and niobium nitrides, and almost the same effect was obtained.

[Example 2] In this example, molybdenum chloride 8 was deposited on metal nitride 7 by chemical vapor deposition using a molybdenum chloride source instead of tungsten in Example 1. As the nitride, cobalt was deposited to a thickness of 50 nm by sputtering, and then heat treated in an ammonia gas atmosphere to form cobalt nitride. To form electrodes and wiring, the molybdenum layer was first processed using an anisotropic dry etching technique using sulfur fluoride gas using a resist as a mask. Next, using these as masks, cobalt nitride was processed into the same shape as the molybdenum layer using an ion silling device to form electrodes and wiring. The cobalt nitride of this example also showed the same effect as Example 1. Further, nickel nitride was formed using the same method, and the effects of the present invention were confirmed. However, the chromium, tungsten, and molybdenum nitrides formed by the sputtering method were formed by ammonia gas heat treatment as in this example, but the electrodes and wiring were formed on them by chemical vapor deposition. Processed at the same time as molybdenum or tungsten.

〔Effect of the invention〕

According to the present invention, it is possible to prevent tungsten or molybdenum formed on a semiconductor device by chemical vapor deposition from peeling off, and also to prevent boron and phosphorus impurities contained in the interlayer insulating film and the diffusion layer in the silicon substrate from penetrating into the metal. This has the effect of preventing an increase in contact resistance between the electrode and the diffusion layer.

Furthermore, since metal nitrides and silicon layers do not show any noticeable reaction up to high temperatures of around 1000°C, high-temperature heat treatment becomes possible even in the production of semiconductor devices using tungsten or molybdenum electrodes and wiring, increasing the flexibility of the manufacturing process. It has the effect of improving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. 1... n-type well provided in Si substrate, 2... p
type well, 3...p + diffusion layer, 4...n÷diffusion layer,
5... Inter-element isolation insulating film, 6... Interlayer insulating film, 7.
...Metal nitride layer, 8... tandem layer formed by chemical vapor deposition method 9 u/,,,fl'! l-well 8...

Claims (1)

[Claims] 1. Metals belonging to groups IVa, Va, and VIa of the element synchronization table,
In addition, metals such as cobalt and nickel or their silicon compounds are made into nitrides, and tungsten or molybdenum is deposited by chemical vapor deposition on the layer.
An electrode/wiring for a semiconductor device characterized by processing these layers into a desired shape.