JPH02186633A - Semiconductor device and manufacture thereof of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to avoid a trouble due to an electromigration and a stress-migration by a method wherein an interface layer due to ion irradiation is formed on the interface between an insulating layer and a wiring layer. CONSTITUTION:A wiring layer 1 and an insulating layer 2 are formed and thereafter, impact is inflicted on atoms constituting the layers 1 and 2 by ion irradiation. Moreover, the atoms in the layer 2 are sputtered in the interior of the layer 1 to diffuse in the layer 1 and reversely, the atoms in the layer 1 are diffused in the layer 2 and an interface layer is formed in the vicinity of the interface between the layers 1 and 2.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a highly integrated semiconductor device having fine wiring and a method for manufacturing the semiconductor device, and more particularly, to Concerning techniques for improving migration resistance and stress migration resistance.

(Prior Art) In recent years, with the rapid development of semiconductor technology, there continues to be a demand for higher density and higher integration of semiconductor devices.

Due to the demand for high density and high integration, electromigration and stress migration have become major issues in semiconductor devices with fine wiring. In other words, this electromigration is
This is a phenomenon in which mass movement is induced by electric current in wiring that is maintained at room temperature or higher. When this phenomenon occurs,
Because the conductive material that makes up the wiring is partially removed or accumulated, disconnections or short circuits may occur in the wiring. Stress migration is a phenomenon in which mass movement is induced by internal stress in wiring that is kept above room temperature without current flowing. When this phenomenon occurs, it causes local disconnections in the wiring. becomes.

In order to prevent this electromigration and stress migration, aluminum alloys have conventionally been used as a conductive material constituting minute wiring provided in semiconductor integrated circuits.

For example, 1 to 10% by weight of aluminum (AI),
The aluminum alloy wiring preferably formed by adding 2% by weight of copper (Cu) (Japanese Unexamined Patent Publication No. 4951871)
The purpose is to suppress the movement of AI atoms by CuA1□ particles interposed in the A1 grain boundaries, and the use of this alloy wiring extends the average lifespan against electromigration.

(Problem to be Solved by the Invention) However, as the circuit density of integrated circuits increases and the width of wiring for interconnection becomes finer as devices become smaller, the above-mentioned Cu-added A1 Even with alloy wiring, sufficient resistance to electromigration cannot be obtained. In particular, the wiring width is 1.5 μm
Below this, the f injection amount was such that failures likely to be caused by electromigration and stress migration became noticeable.

An object of the present invention is to solve the above-mentioned problems, and to provide a semiconductor device and a method for manufacturing a semiconductor device that can avoid failures due to electromigration and stress migration in forming fine-width wiring corresponding to high integration. The purpose is to

[Structure of the invention]

(Means for Solving the Problems) As a result of extensive research to achieve the above object, the present inventors have developed an approach to reduce electromagnetic effects in microwirings by forming an interface layer by ion irradiation at the interface between an insulating layer and a wiring layer. The present invention was completed based on the discovery that migration resistance and stress migration resistance are significantly improved.

That is, the present invention provides a method for manufacturing a semiconductor device that includes the steps of forming a wiring layer on a semiconductor substrate via an insulating layer, and forming an insulating layer covering the wiring layer.
A process of irradiating ions capable of forming an interface layer is added to the interface between the insulating layer and the wiring layer to generate a strong interface layer at the interface, thereby suppressing wire breakage due to electromigration and stress migration. It is something to do.

This ion irradiation forms a wiring layer on the semiconductor substrate via an insulating layer, and after forming an insulating layer covering this wiring layer,
It may be applied to the entire semiconductor substrate to form an interface layer at each interface between the wiring layer and an insulating layer on the lower side and upper side of this wiring layer, or it may be applied to the entire semiconductor substrate to form an interface layer on the interface between the wiring layer and the insulating layer on the lower side and the upper side of this wiring layer. After forming the wiring layer, an interface layer is first formed at the interface between the insulating layer and the wiring layer, and then an insulating layer covering the wiring layer is formed, and the wiring layer and this wiring layer are separated by ion irradiation again. A method may also be used in which an interface layer is formed at the interface with an insulating layer covering the substrate.

In the present invention, examples of materials constituting the wiring layer include aluminum alloys such as Al-3t and Al-3i-Cu, and copper alloys.

Further, in the present invention, examples of the material constituting the insulating layer include inorganic compounds such as silicate glass, silicon nitride, and silicon oxynitride, and organic compounds such as polyimide resin.

In the present invention, the types of ions to be irradiated include inert gas such as argon (Ar), silicon (Si
), oxygen (0□), etc.

The accelerating voltage during ion irradiation is 10 keV or more.
000 keV or less is desirable. This setting is
A voltage of 10 keV or more is required for ions to pass through the interface between the wiring layer and the insulating layer below or above this wiring layer, and an accelerating voltage of 1000 keV or more will destroy the active material formed in the semiconductor substrate. This is because it damages the layer.

In addition, the ion irradiation amount is 10'4/CIf or more 102
Desirably less than °/d. This setting is 10′4 pieces/c
I11 or less is insufficient to diffuse atoms near the interface between the wiring layer and the insulating layer by impact to form an interface layer;
This is because if the number is more than 1020 pieces/d, the effect will not be increased and, on the contrary, damage to the wiring layer and insulating layer will increase.

Note that when ion irradiation is performed on the interface between the wiring layer and the insulating layer, the irradiation may be performed in several parts.

(Function) The present inventor has conducted various studies on the disconnection phenomenon caused by electromigration and stress migration, the structure of wiring layers, and the like. As a result, the width of the wiring layer made of aluminum alloy is 1 month.

When the thickness is about 5 μm or less, as shown in FIG. 1, the wiring layer 1 often takes a so-called bamboo structure in which single crystals of the metal crystals constituting the wiring layer 1 are lined up in a row along its longitudinal direction. It has been found that when a disconnection occurs due to electromigration or stress migration in the wiring layer 1 of such a bamboo structure, it is strongly controlled by the properties of the interface 3 between the wiring layer 1 and the insulating layer 2, as described later. did.

For example, electromigration is a phenomenon in which current, or electrons, collide with and activate atoms in the wiring material, accelerating the diffusion of atoms, and this diffusion of atoms promotes the generation and growth of voids, resulting in wire breakage. However, as shown by the arrow in Figure 2, atomic diffusion 4 occurs frequently at the interface 3 between the wiring layer 1 and the insulating layer 2 when a current is passed through the wiring held above room temperature. . That is, it can be seen that the diffusion 4 of atoms at this interface 3 contributes to electromigration.

Further, voids 5 often occur at points of contact between grain boundaries 6 and interfaces 3. Therefore, it can be said that electromigration depends on the properties of the interface 3 between the wiring layer 1 and the insulating layer 2, ie, the microstructure, interface energy, strength, etc.

Stress migration is a phenomenon in which the triaxial tensile stress in the wiring layer caused mainly by thermal stress accelerates the diffusion of atoms, promoting the generation and growth of voids and leading to disconnection. As shown, atomic diffusion 7 in the wiring that is kept above room temperature and no current is flowing occurs frequently at the interface 3 between the wiring layer 1 and the insulating layer 2, and the atomic diffusion 7 at this interface 3 It can be seen that 7 contributes to stress migration.

Further, voids 5 also occur and grow from the contact points between grain boundaries 6 and interfaces 3.

Due to the nature of this electromigration and stress migration, in order to prevent electromigration and stress migration especially in the wiring layer 1 having a bamboo structure crystal with a small wiring width, atoms at the interface 3 between the wiring layer I and the insulating layer 2 must be It can be seen that it is effective to suppress the interfacial diffusion of , and it is also effective to reduce the energy of the interface 3 and grain boundaries 6, which are the sites where voids 5 occur.

In the present invention, after forming the wiring layer l and the insulating layer 2,
By bombarding the atoms constituting the wiring layer 1 and the insulating layer 2 with ion irradiation, the atoms of the insulating layer 2 are internally sputtered and diffused into the wiring layer l, and conversely, the atoms of the wiring layer l are insulated. By sputtering into layer 2,
An interface layer is formed near the interface 3 between the wiring layer 1 and the insulating layer 2. Due to the diffusion of the atoms of the insulating layer 2 into the wiring layer 1 and the formation of an interface layer by the atoms of the wiring layer 1, the diffusion of the atoms of the wiring layer 1 at the interface 3 is suppressed, and the wiring layer 1 is subjected to electric current and thermal stress. It is possible to prevent failures such as wire breakage due to electromigration and stress migration caused by atomic diffusion when ions are applied.

Furthermore, when the atoms constituting the wiring layer 1 and the insulating layer 2 are bombarded by ion irradiation, crystal defects such as voids 5 and interstitial atoms are induced in the crystal of the wiring layer 1, resulting in an increase in wiring resistance and crystallization. An increase in the diffusion rate within the grains may adversely affect electromigration and stress migration. To deal with this adverse effect, a temperature of 1/4 to 3/4 of the absolute melting point of the material constituting the wiring layer l,
For example, in the case of AI, the melting point at absolute temperature is 933, so annealing at a temperature of 233 to 700, which is 1/4 to 3/4 of that, will substantially affect the generated interface layer. The induced crystal defects can be removed without causing any damage.

Further, the wiring layer 1 may be formed of two or more layers such as silicide and metal, but in this case as well, a strong interface layer is generated between the wiring layer 1 and the insulating layer 2 by ion irradiation. Both have the advantage that the interface between two or more types of wiring layers is strongly bonded, diffusion at the interface can be suppressed, and contact resistance between the wiring layers can be reduced.

(Example) Hereinafter, an example of the semiconductor device according to the present invention will be described.
This will be explained with reference to FIG.

First, C was applied to the surface of the silicon substrate 8 (diffusion layer not shown).
Film thickness 1 made of borate phosphate silicate glass by VD method
．． An insulating layer 2a having a thickness of 2±0.2 μm was formed. A predetermined pattern such as a contact hole (not shown) was formed in this insulating layer 2a by a lithography process. Next, Al-
Sputtering was performed using a 0.5% Si alloy as a target to form an A I -0.5% S film with a film thickness of 08-0.1 μm.
After depositing the i-layer, the width is 1.2μ by a lithography process.
A wiring layer 1 of m was formed. Subsequently, an insulating layer 2b made of phosphosilicate glass and having a thickness of 0.5±0.1 μm was formed on the entire surface by CVD. After that, using an ion irradiation device, argon ions (Ar+
) 5X10Is/c+! Irradiated. Further, annealing heat treatment was performed at 350° C. for 15 minutes in the atmosphere.

For comparison, a semiconductor device was manufactured that was completely the same as the above example except for ion irradiation.

2X106A/ci! A current of 2 is passed through the atmosphere,
The failure rate due to electromigration was measured after holding at 00°C for 500 hours. As a result, the failure rate was 7% in the comparative example without ion irradiation, whereas
No failures were observed in the examples.

Further, other semiconductor devices manufactured in the above Examples and Comparative Examples were held in the atmosphere at 180° C. for 2000 hours, and the failure rate due to stress migration was measured. As a result, in a comparative example without ion irradiation, the failure rate was 12%.
In contrast, no failure was observed in the example.

〔Effect of the invention〕

As detailed above, according to the semiconductor device and the method for manufacturing a semiconductor device according to the present invention, failures due to electromigration and stress migration can be effectively prevented, and this is particularly noticeable when the wiring width is 2 μm or less. It is possible to achieve high reliability of the element in fine wiring, such as the effects seen, and its industrial usefulness is extremely high.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of wiring in a bamboo structure, Fig. 2 is a schematic diagram of wiring rupture due to electromigration, and Fig. 3 is a schematic diagram of wiring rupture due to stress migration.
FIG. 4 is a sectional view of a semiconductor device manufactured in an example of the present invention. 1... Wiring layer 2.2a, 2b... Insulating layer 3... Interface 4, 7... Diffusion of atoms 5.
...Void 6...Grain boundary

Claims (2)

[Claims] (1) In a semiconductor device in which a wiring layer and an insulating layer covering the wiring layer are formed on a semiconductor substrate via an insulating layer, an interface layer formed by ion irradiation is provided at the interface between the insulating layer and the wiring layer. A semiconductor device characterized by: (2) In a method for manufacturing a semiconductor device, the method includes forming a wiring layer on a semiconductor substrate via an insulating layer, and forming an insulating layer covering the wiring layer, at an interface between the insulating layer and the wiring layer. 1. A method for manufacturing a semiconductor device, comprising the step of applying ion irradiation capable of forming an interface layer.