JPS6388843A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve performance and reliability and lengthen lifetime by forming an upper surface and a lower surface in copper film wirings coated with aluminum layers, lowering the resistance of the film wiring constituting a circuit and preventing disconnection due to migration. CONSTITUTION:An n<+> type diffusion region 2 organizing a semiconductor element is shaped to the surface of a p-type Si substrate 1, an silicon dioxide (SiO2) lower-layer insulating film 3 is formed onto the substrate, and a wiring contact window 4 from which the n<+> type diffusion region 2 is exposed is shaped to the lower-layer insulating film 3. A Cu film wiring 7, a lower surface of which has a first Al layer 5 in approximately 1000Angstrom thickness and an upper surface of which is coated with a second Al layer 6 in approximately 1000Angstrom thickness and which has thickness of approximately 6000-8000Angstrom , is brought into contact with the n<+> type diffusion region 2 in the wiring contact window 4 section and extended and disposed onto the lower-layer insulating film 3, and a coated insulating film 8 consisting of phosphosilicate glass (PSG) is formed onto the disposing surface of the Cu film wiring 7.

Description

[Detailed description of the invention] [Summary] By covering the upper and lower surfaces with an aluminum (^l) layer, it is possible to increase wiring resistance due to oxidation and improve device characteristics due to diffusion during heat treatment during vapor phase growth of a covering insulating film, etc. A semiconductor device that uses copper (Cu) wiring that prevents deterioration, reduces wiring resistance, and prevents disconnection due to electromigration and stress migration.

[Industrial application field]

The present invention relates to semiconductor devices, and particularly to improvements in the wiring structure of semiconductor devices.

2. Description of the Related Art Semiconductor integrated circuit devices (ICs) are becoming increasingly large-scale and highly integrated, such as LSIs and ultra-LSRs, and the width of wiring forming circuits is also becoming extremely narrow.

As the wiring width decreases, the performance and reliability life of the semiconductor device decreases due to an increase in wiring resistance, an increase in the incidence of disconnection, etc., and improvements are desired.

[Conventional technology]

Aluminum (A) is used as a wiring material for semiconductor devices because it is easy to form, has oxidation resistance, and has low electrical resistance.
I) is commonly used.

In recent years, the phenomenon of spilling that occurs between diffusion regions that have become shallower due to higher integration, or A
From the viewpoint of preventing bond breakdown due to the phenomenon that silicon (St) melts into I and forms a recess on the Si surface, 1.
Al--Si alloy wiring containing approximately 3% silicon (Si) has become particularly popular.

However, in interconnects whose main component is A1, such as the above-mentioned Al-5 alloy, when the interconnect width is extremely narrowed and its cross-sectional area is significantly reduced, the electromigration effect increases due to the increase in current density. Disconnection is likely to occur due to stress migration due to tensile stress caused by the difference in coefficient of thermal expansion between the semiconductor device and the insulating film, resulting in a reduction in the reliability and life of the semiconductor device.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is that, as mentioned above, the Al wiring commonly used in semiconductor devices is
When the wiring width is reduced, wire breaks are more likely to occur due to electromigration or stress migration, reducing the reliability and lifetime of semiconductor devices.

[Means for solving problems]

The above problem is that the top and bottom surfaces are made of aluminum layers (5) (
The problem is solved by the semiconductor device according to the present invention, which includes a copper-coated wiring (7) covered with (6).

[Function] That is, the present invention protects the upper surface with an A1 layer to prevent wiring by oxidation in processes that involve oxidation after wiring formation, such as vapor phase growth of a covering insulating film performed at a high temperature of about 350 to 430°C. It prevents an increase in resistance and also has A1 on the bottom surface.
By providing a layer to prevent deterioration of semiconductor device performance due to the diffusion of the wiring material into the Si substrate at the high temperature at the contact portion of the wiring with the Si substrate, it is possible to This makes it possible to use Cu as a wiring material, which is advantageous in reducing wiring resistance and has an electromigration resistance that is about 100 times that of 81, and also has excellent stress migration resistance. This is intended to improve the performance, reliability, and lifespan of highly integrated semiconductor devices by suppressing an increase in wiring resistance and preventing disconnection when semiconductor devices become highly integrated and the wiring width becomes extremely narrow. It is.

〔Example〕

The present invention will be specifically explained below with reference to illustrated embodiments.

FIG. 1 is a schematic side sectional view showing one embodiment of the present invention;
Figures (a) to (e) are process cross-sectional views of the method for forming Cu wiring according to the present invention.

Identical objects are indicated by the same reference numerals throughout the figures.

The semiconductor device according to the present invention, for example, as shown in FIG.
An n-type diffusion region 2 constituting a semiconductor element is formed on one surface of a p-type St substrate, and silicon dioxide (Si) is formed on the substrate.
O2) A lower insulating film 3 is formed, a wiring contact window 4 exposing the n-type diffusion region 2 is formed in the lower insulating film 3, and a first layer 5 with a thickness of about 1000 is formed on the lower surface. and the upper surface is covered with a second Al16 layer with a thickness of about 6000 to 8000 mm.7
is disposed in the wiring contact window 4 portion in contact with the n" type diffusion region 2 and extending on the lower layer insulating film 3, and the C
A covering insulating film 8 made of phosphosilicate glass (PSG) is formed on the surface on which the u-covered wiring 7 is provided.

The second layer 6 provided on the upper surface of the Cu-coated wiring 7 is made of carbon when the coating insulating film 8 is formed by vapor phase growth.
The first A1 layer 5 provided on the lower surface has a protective function of preventing oxidation of the upper surface of the U-coated wiring 7, and the
In order to have a barrier function of preventing u from diffusing into the Si substrate such as the n-type diffusion region 2, and to sufficiently fulfill the above protection function and barrier function, the first and second A1 layers 5. The thickness of 6 is required to be at least 1000 Å or more.

In addition, since the specific resistance of Cu is about 81:2 parts 3 as mentioned above, the thickness of the Cu coated wiring 7 to obtain the same wiring resistance as the conventional 1 μm thick Al wiring is as follows. 1. Considering the existence of the second A1 layer 5.6, it is sufficient to have about 6,000 or more people.

The Cu coated wiring 7 according to the present invention described above can be used, for example, in the following manner.
It is formed by the method described with reference to FIGS.

Refer to FIG. 2 Fal. That is, first, an n-type diffusion region 2 constituting a semiconductor element is formed on a p-type Si substrate 1 by a conventional method, and then a diffusion region 2 is formed on the substrate by thermal oxidation and chemical vapor deposition (CVD) as usual. For example, a lower layer insulating film 3 having a thickness of about 6,000 to 8,000 layers is formed, and a wiring contact window 4 exposing the n-type diffusion region 2 is formed in the lower layer insulating film 3 by ordinary lamination technology. A first AI layer 5 with a thickness of about 1,000 layers is deposited on the substrate to be processed using a normal sputtering method.
, a Cu coating 7 with a thickness of about 6,000 to 8,000 layers, and a second 11 layer 6 with a thickness of about 1,000 layers are sequentially formed.

Referring to FIG. 2(b), a thickness of 20 mm is then deposited on the second A1 layer 6 by the CVD method.
About 00 people form a titanium nitride (TiN) film 109,
A resist film pattern IO having a shape corresponding to the wiring pattern is formed on the TiN film 109, and using the resist film pattern IO as a mask, the TiN film 109 is etched by reactive ion etching (RIE) using chlorine gas.
and the second A1 layer 6 are selectively etched away.

Refer to FIG. 2 FC+ Next, after removing the resist film pattern 10, a pattern of TiN film 109 having a shape corresponding to the wiring pattern formed by the above etching process, that is, a Ti
Using the N film pattern 9 as a mask, the Cu film 107 is selectively etched by ordinary ion beam etching (ion milling) using argon. Here, a pattern of Cu film wiring 7 is formed.

FIG. 2 (see di) Next, using the TiN film pattern 9 as a mask, the first At layer 5 is selectively etched and removed by RIB treatment using chlorine-based gas, and then over-etching is performed to remove the TiN film pattern 9. By removing it, a Cu-coated wiring 7 according to the present invention having a first AI layer 5 on the lower surface and covered with a second 41 layer 6 on the upper surface is formed.

Refer to FIG. 2 (tel) Next, a PSG covering insulating film 8 is formed on the wiring formation surface by the CVD method.

Thereafter, the semiconductor device according to the present invention is completed by exposing the bonding pads (not shown), dicing, bonding, etc.

As shown in the above embodiments, in the semiconductor device according to the present invention, the second AI layer 6 is provided on the upper surface to prevent Cu from being oxidized during high-temperature treatment during vapor phase growth of a coating insulating film, and the lower surface is provided with the By providing the first A1 layer 5 that prevents Cu from diffusing into the Si substrate during processing, defects that degrade wiring and semiconductor elements can be eliminated, and specific resistance can be reduced to A1.
Cu, which is smaller than I and has much higher resistance to electromigration and stress migration than Δ1, was used as a film wiring for circuit formation.

Therefore, the performance of the semiconductor device is improved because the wiring resistance can be lowered than in the past, and the reliability and life of the semiconductor device is improved because disconnection is prevented.

〔Effect of the invention〕

As described above, according to the present invention, the resistance of the film wiring constituting the circuit is reduced, and disconnection due to migration is also prevented, thereby improving the performance and reliability of the semiconductor device.

[Brief explanation of the drawing]

FIG. 1 is a schematic side cross-sectional view showing an embodiment of the present invention, and FIG. Substrate, 2 is an n diffusion region, 3 is a lower insulating film, 4 is a wiring contact window, 5 is a first layer, 6 is a second layer, 7 is a Cu film wiring, 8
1 is a coating insulating film, 9 is a TiN film pattern, 1O is a resist pattern, 107 is a Cu film, and 109 is a TiN film.

Claims (1)

[Claims] A semiconductor device comprising a copper film wiring (7) whose upper and lower surfaces are covered with aluminum layers (5) and (6).