JPS62234344A - Al alloy containing b 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 and N of one kind or two kinds or more of alloying elements selected from a group consisting of Ti, etc., B, N and Al and unavoidable impurities. CONSTITUTION:An Al alloy containing B and N is organized of 0.002-0.7wt. % alloying elements of one kind or two kinds or more selected from a group composed of Ti, Zr, Rf, V, Nb, 'ra, Cr, Mo and W, 0.002-0.5 wt. % B, 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 and N are changed into MeBx and MeNx on casting in a target board prepared in this manner, a nucleate 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 hillocks.

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 is obtained by X-vacuum deposition.

(c) Good adhesion to silicon oxide film (S i 0.).

(d) Chemically stable and S i 0. and does not react.

(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, a 1-1 wt % 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 (voids) are generated in the traces of the movement of Al atoms, 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 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. 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 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 have conducted extensive research on alloying elements. As a result of stacking, Ti, Zr, Hf, V, Nb
, Ta, Cr, Mo, and W. We found that adding one or more alloying elements selected from the group consisting of M a & B and N has a large grain boundary diffusion suppressing effect, and based on this knowledge, we As a result, the present invention was completed. This is considered to be because M e B x particles and M e N x particles, which are compounds of Me, B, and N, contribute to suppressing grain boundary diffusion.

[Configuration of the Invention That is, the present invention includes the following: (1) Tx t Z r', Hf y Vp Nb
tTap One or more alloying elements selected from the group consisting of CreMo and W in an amount of 0.002 to 0.7
wt%.

B 0.002~0.5wt%, N 0.002~
B-containing Al alloy for semiconductor wiring material consisting of 0.5 wt%, balance Al and unavoidable impurities, and (2) Zr, H
One or more alloying elements selected from the group consisting of f, V, Nb, Ta, Cr, MQ and W at 0.002
~0.7wt%, B0.002~0.5wt%, N0.
002-0.5wt%v SIO-5-1.
5wt%.

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

[Effects of the Invention] The B and N-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.

If the amount of B added in the alloy composition of the present invention is 0.002 wt%, it will be completely dissolved in the wiring material Al or Al-8i alloy, and M e B x will not precipitate, and 0. If the amount exceeds 5 wt%, the electrical resistance of the wiring increases, which is undesirable, so the amount added is set at 0.002 to 0.5 wt%. If the amount of N added is less than 0.002 wt%, it will be solid dissolved in the wiring material Al or Al-Si combined Si, and M e N x will not precipitate, and if it exceeds 0.5 wt%. Since this increases the electrical resistance of the wiring, which is undesirable, the amount added is set at 0.002 to 0.5 wt%. Ti, Zr
, Hf, V, Nb, Ta, Cr, Mo, and W, if the amount of one or more alloying elements Me selected from the group consisting of Or M becomes a complete solid solution in the Al-8i alloy.
e B x or MeNx does not precipitate, and 0.7 wt%
If it exceeds this, the electrical resistance of the wiring will increase, which is undesirable, so the amount added is set at 0.002 to 0.7 wt%. More preferably, Si can be added to the Al-Me-B-N alloy of the present invention to suppress interdiffusion between semiconductor Si and Al. A if the amount of Si added is less than 0.5%
The effect of preventing interdiffusion of Si and Al in the l-8i contact part is small, and if it exceeds 1.5 wt%, the electrical resistance of the wiring increases, which is undesirable, so the amount added should be 0.5 to 1.
．． It is set to 5wt%.

The above aluminum alloys for semiconductor wiring materials are usually high purity (99,999wt%) Al or high purity (99,999wt%) Al.
9 wt%) 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 N are AIN
.

SiN, M e N x, etc. can be melted and cast in the atmosphere, and then the 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, during the above-mentioned casting, some of Me, B and N are converted into M e B x and M
e N x, this MeBX and M s N
x causes a nuclear effect, making the casting structure finer, and since there are large amounts of Me, B, and N remaining in the casting material, the uniformity of the thin film produced by sputtering or vacuum evaporation is extremely excellent, and furthermore, in this thin film, The aforementioned Me, B, and N become M e BX and M a N x and are pushed out to the grain boundaries, and act 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, M e
B x and M e N x precipitate 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-8
i alloy, high purity (99.95 wt%) crystal B, high purity (99.95 wt%) AIN 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 investigate the characteristics of this thin film, a current with a current density of 1x10@A/am' was passed continuously at a temperature of 175°C.The average time until failure occurs at that time (average failure time)
are shown in Table 1.

Table 1 also shows test results for pure Al, At-CU gold alloy, and Al-Cu-8i alloy as comparative examples.

As is clear from Table 1 above, conventional pure Al, Al-
1 compared to the Cu alloy and the A1-Cu-Si alloy.
-8i-Al-8i-The mean failure time of the vapor-deposited wiring film under high temperature and continuous energization is significantly improved, and the
-It is more than twice that of Cu-8i alloy. In this way, the A1-Me-B-N alloy of the present invention and the AI
Si Me-B-N alloy is 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.

[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%, N0.002-0.5wt%, balance Al
B and N-containing Al alloys for semiconductor wiring materials, which consist 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, B0.002 to
0.5wt%, N0.002-0.5wt%, Si0.
A B and N-containing Al alloy for semiconductor wiring materials, consisting of 5 to 1.5 wt%, the balance being Al and unavoidable impurities.