JPS62234345A - Al alloy containing n and c for semiconductor wiring material - Google Patents

Abstract

PURPOSE:To prevent the generation of electromigration and hillocks by constituting an Al alloy containing N and C of one kind or two kinds or more of alloying elements selected from a group consisting of Ti, etc., N, C and Al and unavoidable impurities. CONSTITUTION:An Al alloy containing N and C is organized of 0.002-0.7wt. % 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. % N, 0.002-0.5wt. % C and Al and unavoidable impurities as the remainder. An A%l-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 semiconduc tor wiring material. One parts of Me, N and C are changed into MeNx and MeCx 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 Al alloy precipitates to a grain boundary and effectively works for preventing voids by electromigration and the formation of hillocks.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an aluminum aluminum alloy for semiconductor wiring material used for connection wiring of each electrode of an MO5 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 (Sin).

(d) Chemically stable and does not react with SiO□.

(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 disadvantages of the Al wiring film are: (a) It causes electromigration and breaks when the current density exceeds 10@A/cm. Especially during sputtering or vacuum evaporation. It is difficult to form a film with a uniform thickness in areas with steps, and as shown in Figure 1, if a thin area 3 is formed in some areas, the current density in that area increases, causing the above-mentioned electromigration. , the wire may be disconnected from that part.

(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
Atoms obtain kinetic energy by colliding with electrons and move in the direction of electron movement, so atomic vacancies are generated in the traces of Al atoms movement, resulting in a decrease in the cross-sectional area of the wiring and an increase in current. This is a phenomenon in which the density further increases and the temperature rises due to Joule heat, etc., which accelerates the growth of voids and eventually leads to wire breakage. This movement of Al atoms is normally caused by grain boundary diffusion that propagates through Al crystal grain boundaries, 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. To prevent this, as with voids, it is effective to block the grain boundaries with some kind of precipitate to make it difficult for grain boundary diffusion to occur.

As mentioned above, in order to prevent voids and hillocks due to electromigration, it is considered effective to precipitate some elements at grain boundaries and suppress grain boundary diffusion.There are several alloying elements that cause precipitation at zero grain boundaries. Elements with high solubility in the matrix cannot be used because they increase the electrical resistance of the Al alloy. Therefore, as a result of intensive research on alloying elements, the inventors found that Ti, Zr, Hf, V, Nb
, found that adding one or more alloying elements Me selected from the group consisting of Ta, Cr, Mo, and W together with N and C has a large grain boundary diffusion inhibiting effect, and based on this knowledge, The present invention has been accomplished. This is M
This is considered to be because M e N x particles and M e Cx particles, which are compounds of e, N, and C, contribute to suppressing grain boundary diffusion.

[Structure of the invention] In other words, one aspect of the present invention is (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.

NO,002~0.5wt%, CO,002~0.
N-containing Al alloy for semiconductor wiring material consisting of 5wt%, balance Al and unavoidable impurities, 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.

NO,002~0.5wt%, GO,00
2-0.5wt%, Si 0.5-1.5wt%
.

Provided is an N- and C-containing Al alloy for semiconductor wiring material, the remainder of which is Al and unavoidable impurities.

[Effects of the Invention] The N and C-containing Al alloy of the present invention is effective in preventing electromigration and hillock formation, and 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.

When the amount of N added in the alloy composition of the present invention is 0.002 wt%, the wiring material Al or A L -S i
M e N x will not precipitate as it will completely dissolve in the alloy, and if it exceeds 0.5 wt%, the electrical resistance of the wiring will increase, which is undesirable, so the amount added should be 0.002 to 0.5 wt.
%. If the amount of C added is 0.002wt%, it will be completely dissolved in the wiring material Al or Al-Si alloy, and M e Cx will not be precipitated.
If the amount exceeds 0.002 to 0.5 wt%, the electrical resistance of the wiring increases, which is undesirable. Ti,
Zr, Hft Vt Nb, Ta, Cr, M
When the amount of one or more alloying elements Me selected from the group consisting of o and W is less than 0.002 wt%, it is completely dissolved in Al or Al-Si alloy as the wiring material. If M a N x or MeCx does not precipitate, and if it exceeds 0.7 wt%, the electrical resistance of the wiring will increase, which is not preferable, so the amount added should be 0.002 to 0.7 wt%.
%. More preferably, Al-Me-N- of the present invention
By adding Si to the C 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-5i 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 0.
．． The content should be 5 to 1.5 wt%.

The above aluminum alloys for semiconductor wiring materials are usually high purity (99,999wt%) Al or high purity (99,4) Al.
Ti, Z
r, Hft Vt Nbt Ta.

One or two selected from the group consisting of Cr, Mo and W
More than one type of alloying element Me, and N) @A I N.

SiN and M e N x, etc., and C is AIC, Si
C, M e Cx, etc. can be melted and cast in the atmosphere, and then this cast material can be machined as it is to make a vacuum evaporation material or a target plate for sputtering. In the target plate created in this way, part of Me, N, and C was converted into Me N x and M e Cx during the above-mentioned casting.
As a result, these M e N x and M e Cx cause a nucleation effect, making the casting structure finer, and the large amount of Me, N, and C remaining in the casting material impairs the uniformity of the thin film produced by sputtering or vacuum evaporation. Furthermore, in this thin film, the above-mentioned Me, N and C are
eNx and MeCx, which precipitate at grain boundaries and act extremely effectively to prevent the formation of voids and hillocks due to electromigration. In addition, instead of a cast material, it is also possible to process the material into a predetermined shape after casting and further heat-treat it to make a sputtering or vacuum evaporation material. In this case, when the material is recrystallized by heat treatment, M e N x and M e Cx are precipitated, the crystals become finer due to the nucleation effect, and the uniformity of the structure of the sputtered or vacuum evaporated material is improved. 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 AI
-Si alloy, high purity (99.95wt%) AIN,
High purity (99.95wt%) AIC and Ti, Zr,
Hf, V, Nb, Ta, Cr.

After adjusting one or more types of high-purity metal Me selected from the group consisting of Mo and W to the composition shown in Table 1, it is charged into a high-purity aluminum crucible and heated in the atmosphere in a resistance heating furnace. Dissolved. After melting, it was cast into a predetermined 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 with a current density of 1X10'A/cm'' was passed continuously at a temperature of 175°C.

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

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

As is clear from Table 1 above, conventional pure Al, Al7
Compared to Cu alloy and Al-Cu-Si alloy, Al-Me-N-C alloy and A I -S i -M of the present invention
The mean failure time of vapor-deposited wiring films made of e-N-C alloys at high temperatures and under continuous energization has been significantly improved, and Al-C
This is more than twice that of u-Si alloy. In this way, the Δl-Me-N-C alloy of the present invention and A l -S i -
The M e -N -C alloy is effective in preventing the formation of voids and hillocks due to electromigration,
It can be seen that it is an extremely excellent material for wiring and materials for semiconductor integrated circuits.

[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, N0.002 to
0.5wt%, C0.002-0.5wt%, balance Al
and N and C-containing Al alloys for semiconductor wiring materials, which are composed of 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, N0.002 to
0.5wt%, C0.002-0.5wt%, Si0.
An N and C-containing Al alloy for semiconductor wiring materials, consisting of 5 to 1.5 wt%, balance Al and unavoidable impurities.