JPS62240739A - B-, c-, and n-containing aluminum alloy for semiconductor wiring material - Google Patents

Abstract

PURPOSE:To prevent the breaking of wires and a short circuit between adjacent wirings, by adding, together with B, C, and N, specific amounts of Ti, Ar, Hf, V, Nb, Ta, Cr, Mo, and W to Al containing elements having an elec tromigration-preventing effect, such as Cu, etc. CONSTITUTION:0.0001-0.02% one or more alloying elements M by weight, among Cu, Co, Mn, Ni, Sn, In, Au, and Ag, 0.002-0.07% of one or more alloying elements Me among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, 0.002-0.5% respectively, of B, C, and N, and, if necessary, 0.5-1.5% Si are added to Al. In the above composition, when the additive quantities of the elements B, C, N, and Me are less than the above ranges, B, C, N, and Me perfectly enter into solid solution in Al or Al-Si alloy and therefore MeBx, MeCx, and MeNx are not precipitated and, when they exceed the above ranges, electric resistance is increased. This alloy is used as wiring material for semiconductor device in sputtering and vapor deposition and is effective in preventing electromigration and hillock formation.

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.

Currently, AI deposited films are often used as 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 (SiO2).

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

(e) Processing with photoresist is easy.

(to) Good lead bonding properties.

This is because it is considered to be advantageous overall. An Al-1wt%Si alloy is usually used as the vapor deposition material 1 alloy.

[Problems to be Solved by the Invention] On the other hand, the disadvantages of the AI wiring film are: (a) Electromigration occurs and the wire breaks when the current density exceeds 10'A/am''. In particular, it is difficult to form a film to 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 will be high. -Migration may occur and 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 to solve the problem] Electromigration is the process by which AI is produced under high current density.
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 movement of A I 1M atoms, and as a result, the cross-sectional area of the wiring decreases. However, the current density increases further, causing a rise in temperature due to Joule heat, etc., which accelerates the growth of voids, eventually leading to wire breakage. This A
The movement of I atoms is normally caused by grain boundary diffusion that propagates through the crystal grain boundaries of Al, and if the grain boundaries are blocked with some kind of precipitate, grain boundary diffusion is difficult to occur. Rielec I-ROM migration prevents the generation and growth of voids. be able to.

Next, hillocks are formed by AIJW molecules 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 some 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, as a result of extensive research into alloying elements, the inventors found that Ti, Zr, Hf, V, Nb
, Ta, Cr, Mo, and W, and one or more alloying elements Me selected from the group consisting of B.

When added together with C and N, the effect of suppressing grain boundary diffusion is large, and furthermore, Cu, Co, and M, which are metal elements that are known to be effective in preventing electromigration, are added.
Adding a small amount of one or more alloying elements M selected from the group consisting of n, Ni, Sn, In, Au, and Ag further increases the effect of inhibiting grain boundary diffusion and increases the electromigration prevention effect. The present invention was made based on this finding.

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

(1) 0.0001 to 0.02 wt% of one or more alloying elements selected from the group consisting of Cu, Co, Mn, Ni, Sn, In, A-static U, and Ag, Ti,
Zr, Hf# 0.002 to 0.7 wt% of one or more alloying elements selected from the group consisting of V, Nb, Ta, Cr+Mo, and W.

B 0.002~0.5wt%, G 0.002~
0.5 wt%, N 0.002 to 0.5 wt%, balance B for semiconductor wiring material consisting of Al and unavoidable impurities;
C, N-containing aluminum alloy and (2) one or more alloying elements selected from the group consisting of Cu, Co, Mn, Ni, Sn, In, Au and Ag in an amount of 0.0001 to 0. 02wt%, 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.
02-0.5wt%, G 0.002-0.5wt%
, N 0.002-0.5 wt%.

B and C for semiconductor wiring materials consisting of 0.5 to 1.5 wt% Si, the remainder AI and unavoidable impurities.

Provided is an N-containing aluminum alloy.

[Effects of the Invention] The B, C, and N-containing aluminum 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.

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 AI or Al
-MeBx, M'eC are completely dissolved in Si alloy.
x and M e N x do not precipitate, and if it exceeds 0.5 wt%, the electrical resistance of the wiring increases, which is not preferable.
Let it be wt%.

Ti, Zr, Hf, V, Nb, Ta, Cr, M.

If the addition amount of one or more alloying elements Me selected from the group consisting of However, MeBx, MeCx or M e N x will not precipitate, and if it exceeds 0.7 wt%, the electrical resistance of the wiring will increase, which is undesirable, so the amount added should be 0.002 to 0.
．． It is set to 7wt%. Also, Cu, Co, Mn, Ni, S
n, In.

If the addition amount of one or more alloying elements M selected from the group consisting of Au and Ag is less than 0.0001wt%, it will have no effect on preventing electromigration at all, and if it exceeds 0.02wt%, the wiring will fail. Since the electrical resistance becomes large, which is undesirable, the amount added should be 0.0OO1 to 0.0.
It is set to 2wt%.

More preferably, Al-Me-B-C-N- of the present invention
Mutual diffusion of semiconductor Si and Al can be suppressed by adding Si to M alloy.If the amount of S x added is less than 0.5%, Si and Al in a part of Al-Si contact 1 The effect of preventing mutual diffusion is small.

Moreover, if L exceeds 5 wt%, the electrical resistance of the wiring increases, which is not preferable, so 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, TB, Cr, Mo and W, and Cu, Co p M n HN ie S n #
1 selected from the group consisting of I n + A u and Ag
type or two or more types of alloying element M and high purity (99,9
5wt%) of crystal B, Ct & AIC, SiC and M
e Cx, etc., and NteA IN, S i N, M e N can. The target plate made in this way is M e during the above casting.

Parts of B, C and N are MaBx, MeCx and MeNx
Therefore, these MeBx, MeCx and M e N
x causes a nuclear effect and refines the casting structure, and since there are many Me, B, C, and N remaining in the casting material, the uniformity of the thin film by sputtering or vacuum evaporation is extremely excellent, and furthermore, In this thin film, the Me,
B, C and N are MaBx, MeCx and M e N x
Coupled with the effect of the metal element M, which precipitates at grain boundaries and is effective in preventing electromigration, it acts extremely effectively in preventing 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 recrystallized by heat treatment, MeBx, MeCx
and M e N x precipitate, the crystals become finer due to the nuclear effect, and the uniformity of the structure of the sputtering or vacuum evaporation material improves, thereby improving the uniformity of the thin film. I will explain about it.

[Example] High purity (99,999wt%) At or high purity Al-8
i alloy, delivery B with high purity (99.95 wt%), AIC with high purity (99.95 wt%).

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
and Cu, Co, Mn, Ni, and Sn.

After adjusting the composition of one or more alloying elements M selected from the group consisting of In, Au, and Ag 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. It was dissolved in 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 1 x 10''A/cm'' was passed continuously at a temperature of 175°C. Average time to failure at that time (mean time to failure)
are shown in Table 1.

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

As is clear from Table 1 above, conventional pure AL, A
1 compared to 1-Cu alloy and Al-Cu-8i alloy.
Al-Me-B-C-N-M alloy of the present invention and Al-8
The mean failure time of vapor-deposited wiring films made of i-Ms-BAl-8i-alloy under high temperature and continuous energization is significantly improved.
This is more than twice that of Al-Cu-3i alloy. In this way, the A L -M e -B -C-N -M of the present invention
It can be seen that the alloy and AI-8i-Me-BAl-8i-alloy are effective in preventing the formation of voids and hillocks due to electromigration, and are extremely excellent materials as wiring materials 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) 0.0001 to 0.02 wt% of one or more alloying elements selected from the group consisting of Cu, Co, Mn, Ni, Sn, In, Au and Ag, Ti, Zr,
0.00 of one or more alloying elements selected from the group consisting of Hf, V, Nb, Ta, Cr, Mo and W.
2-0.7wt%, B0.002-0.5wt%, C0
．． 002~0.5wt%, N0.002~0.5wt%
, the remainder Al and unavoidable impurities, an aluminum alloy containing B, C, and N for semiconductor wiring materials. (2) 0.0001 to 0.02 wt% of one or more alloying elements selected from the group consisting of Cu, Co, Mn, Ni, Sn, In, Au and Ag, Ti, Zr,
0.00 of one or more alloying elements selected from the group consisting of Hf, V, Nb, Ta, Cr, Mo and W.
2-0.7wt%, B0.002-0.5wt%, C0
．． 002~0.5wt%, N0.002~0.5wt%
, 0.5 to 1.5 wt% Si, the remainder Al and unavoidable impurities, an aluminum alloy containing B, C, and N for semiconductor wiring materials.