JPS62234346A - Al alloy containing b, c and n for semiconductor wiring material - Google Patents

Abstract

PURPOSE:To prevent the generation of electromigration and hillocks by constituting an Al alloy containing B, C and N of one kind or two kinds or more of alloying elements selected from a group consisting of T, etc., B, C, N and Al and unavoidable impurities. CONSTITUTION:An Al alloy containing B, C and N is organized of 0.002-0.7wt. g alloying elements (Me) of one kind or two kinds or more selected from a group composed of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, 0.002-0.5wt. % B, 0.002-0.5wt. % C, 0.002-0.5wt. % N and Al and unavoidable impurities as the remainder. An Al-Si alloy in which high purity (99.999 wt. %) Al or high purity (99.999 wt. %) Si is dissolved is used normally as the aluminum alloy for a semiconductor wiring material. One parts of Me, B, C and N are changed into MeBx, MeCx and MeNx on casting in a target board prepared in this manner, a nuclear effect is generated, cast structure is fined while the uniformity of a thin-film by sputtering or vacuum deposition is improved, and the aluminum alloy precipitates to a grain boundary and effectively works for preventing voids by electromigration and the formation of hollocks.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an aluminum alloy for semiconductor wiring material used for connection wiring of each electrode of an MO8 type semiconductor.

[Prior Art] Semiconductor integrated circuits have developed rapidly in recent years, and as their functions have expanded, thin film metal interconnections that electrically interconnect constituent elements are becoming increasingly finer and denser.

Al-deposited films are currently widely used as thin-film metal interconnects. This is because Al (a) can easily make ohmic contact with silicon.

(b) A film with good conductivity can be obtained by vacuum evaporation.

(c) Good adhesion to silicon oxide film (SiO□).

(d) Chemically stable and does not react with Sin.

(e.) Processing with photoresist is easy.

(f) Good lead bonding properties.

This is because it is considered to be advantageous overall. As the Al alloy for vapor deposition, an Al-1wt%Si alloy is usually used.

[Problems to be Solved by the Invention] On the other hand, the drawbacks of the AI wiring film are: (a) Electromigration occurs and the wire breaks when the current density exceeds 10'A/am". Especially during sputtering or vacuum evaporation. It is difficult to form a film with a uniform thickness in areas with steps.

As shown in FIG. 1, when a thin portion 3 is formed in a portion, the current density in that portion becomes high, so that the above-mentioned electromigration occurs, and the wire may be disconnected from that portion.

(b) Protrusions called hillocks occur between adjacent wires (
In the case of multi-layer wiring, short circuits occur between the layers.

and so on.

[Means for solving the problem] Electromigration is the process by which Al
When the l-son collides with the electron, it gains kinetic energy and moves in the direction of the electron movement, so atomic vacancies (voids) are generated in the traces of the movement of the AI atom, and as a result, the cross-sectional area of the wiring decreases. This is a phenomenon in which the current density further increases, causing a rise in temperature due to Joule heat, etc., which further accelerates the growth of voids, eventually leading to wire breakage. This movement of AI atoms is normally caused by grain boundary diffusion that propagates through the grain boundaries of Al, and if the grain boundaries are blocked with some kind of precipitate, grain boundary diffusion is difficult to occur.To prevent the generation and growth of voids due to reelectromigration. I can do it.

Next, hillocks are formed by Al atoms that have migrated due to the electromigration and protrude toward the surface. In order to prevent this, it is effective to block one grain boundary with some kind of precipitate to make it difficult for grain boundary diffusion to occur, similar to voids.

As described above, in order to prevent voids and hillocks due to electromigration, it is considered effective to precipitate some element at grain boundaries to suppress grain boundary diffusion. There are several alloying elements that cause precipitation at grain boundaries, but elements with high solubility in the matrix cannot be used because they increase the electrical resistance of the Al alloy. Therefore, the present inventors
As a result of intensive research, we found that Ti, Zr, Hf, V, N
b. One or more alloying elements Me selected from the group consisting of Ta, Cr, Mo and W.

It was discovered that the effect of suppressing grain boundary diffusion is large when added together with C and N, and the present invention was completed based on this knowledge. This means that M e B x particles, MaC x particles, and M e N x particles, which are compounds of Me, B, C, and N,
This is thought to be because the particles contribute to suppressing grain boundary diffusion.

[Structure of the invention] That is, the present invention (1) Ti, Zr, Hf, V, Nb, Ta, Cr.

0.002 to 0.7 wt% of one or more alloying elements selected from the group consisting of MO and W.

8 0.002-0.5wt%, G 0.002-0
．． 5wt%, N 0.002-0.5wt%, balance A
B, C for semiconductor wiring materials consisting of l and unavoidable impurities
, N-containing AI alloy and (2) Ti, Zr, Hf,
V, Nb, Ta, Cr.

0.002 to 0.7 wt% of one or more alloying elements selected from the group consisting of Mo and W.

B 0.002~0.5wt%, G 0.002~
0.5wt%, N 0.002-0.5wt%.

B and C for semiconductor wiring materials consisting of 0.5 to 1.5 wt% Si, balance Al and inevitable impurities.

Provided is an N-containing Al alloy.

[Effects of the Invention] The B, C, and N-containing Al alloy of the present invention is effective in preventing electromigration and hillock formation;
It is an extremely excellent material as a wiring material for semiconductor integrated circuits.

[Detailed Description of the Invention] The alloy of the present invention is used as a wiring material for semiconductor devices by sputtering or vacuum deposition.

The amount of each of B, C and N added in the alloy composition of the present invention is 0.00
In the case of 2 wt% undropped, the wiring material Al or A
MeBx, M are completely dissolved in the l-Si alloy.
eCx and M e N x did not precipitate, and 0.5wt
%, the electrical resistance of the wiring increases, which is undesirable.
It is set to 5wt%. Tit Zr, Hf, V, Nb, Ta
The amount of one or more alloying elements Me selected from the group consisting of , Cr, Mo, and W is 0.002 wt%.
If it is not dropped, it will be completely dissolved in Al or At-Si alloy which is the wiring material, and MeBx, MeCX or M
e N x does not precipitate, and if it exceeds 0.7 wt%, the electrical resistance of the wiring increases, which is undesirable, so the amount added is reduced to 0.
．． 0.002 to 0.7 wt%.

More preferably, A l -M e -B - of the present invention
By adding Si to the C--N alloy, mutual diffusion between semiconductor Si and Al can be suppressed. If the amount of Si added is less than 0.5%, the effect of preventing mutual diffusion of Si and Al in the Al-Si contact portion is small, and if it exceeds 1.5 wt%, the electrical resistance of the wiring increases, which is not preferable. Therefore, the amount added is set to 0.5 to 1.5 wt%.

The above aluminum alloys for semiconductor wiring materials are usually high purity (99,999wt%) Al or high purity (99,999wt%) Al.
Ti, Z
One or more alloying elements Me selected from the group consisting of r, Hf, V, Nb, Ta, Cr, Mo, and W, high purity (99.95 wt%) crystal B, and C are AIC.
.

SiC and M e Cx, etc., N5AIN, SiN
and M e N x etc., by melting and casting in the atmosphere,
This cast material can then be machined as is into a vacuum evaporation material or a target plate for sputtering. In the target plate created in this way, during the above casting, part of Me, B, C, and N becomes MeBx, MeCx, and M e N x, and these MeBx, MeCx, and M e N x become nuclei. Because of the large amount of Me, B, C, and N remaining in the cast material, the thin film formed by sputtering or vacuum deposition has excellent uniformity. Me, B, C and N of MeBx, MeCx and M
eNx, which precipitates at grain boundaries and acts extremely effectively to prevent the formation of voids and hillocks due to electromigration. Note that instead of a cast material, it is also possible to process the material into a predetermined shape using a casting machine and further heat treat it to make a sputtering or vacuum deposition material. In this case, when recrystallized by heat treatment, MeBx, MeCx and Ma
N x precipitates and the crystals become finer due to the nuclear effect, improving the uniformity of the structure of the sputtered or vacuum evaporated material. This can also improve the uniformity of the thin film.

Next, an example will be described.

[Example] High purity (99,999wt%) Al or high purity Al
-Si alloy, high purity (99.95 wt%) crystal B,
High purity (99.95wt%) AIC.

High purity (99.95wt%) AIN and Ti.

One or more types of high purity metal Me selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, and W
After adjusting the composition to the composition shown in Table 1, it was charged into a high-purity aluminum crucible and melted in the atmosphere in a resistance heating furnace. After dissolving,
It was cast into a specified mold.

The cast material was machined as it was, cut and polished into a predetermined shape and used as a target plate for sputtering.

A sputtering deposition film having a width of 6 microns and a length of 380 microns was formed on a silicon substrate using the above target plate. In order to examine the characteristics of this thin film, a current was continuously applied at a temperature of 175° C. and a current density of 1×10@A/cm”.

Table 1 shows the average time to failure (average time to failure) at that time.

Table 1 also shows test results for pure Al, At-CU gold alloy, and Al-Cu-Si alloy as comparative examples.

As is clear from Table 1 above, conventional pure AI, Al-
Compared to the Cu alloy and the AL-Cu-Si alloy, the Al-Me-B-C-N' gold alloy of the present invention
-S i -M e -B - The mean failure time of the vapor-deposited wiring film made of the -C-N alloy under high temperature and continuous energization is significantly improved, and is more than twice as long as that of the At-Cu-Si alloy. In this way, Al-M e -B -C- of the present invention
N alloy and Al-8i-MeAl-8i-alloy are effective in preventing the formation of voids and hillocks due to electromigration.

It can be seen that this material is extremely excellent as a wiring material for semiconductor integrated circuits.

Margin below

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a portion where an Al wiring film is deposited on a silicon substrate. 1: Silicon substrate 2: Al wiring film

Claims (2)

[Claims] (1) Ti, Zr, Hf, V, Nb, Ta, Cr, Mo
and 0.002 to 0.7 wt% of one or more alloying elements selected from the group consisting of W, B0.002 to
0.5wt%, C0.002-0.5wt%, N0.0
An Al alloy containing B, C, and N for semiconductor wiring material, consisting of 0.02 to 0.5 wt%, the balance being Al and unavoidable impurities. (2) Ti, Zr, Hf, V, Nb, Ta, Cr, Mo
and 0.002 to 0.7 wt% of one or more alloying elements selected from the group consisting of W, B0.002 to
0.5wt%, C0.002-0.5wt%, N0.0
B for semiconductor wiring material consisting of 02 to 0.5 wt%, Si 0.5 to 1.5 wt%, balance Al and unavoidable impurities;
Al alloy containing C and N.