JPS60206045A - Wiring - Google Patents

Abstract

PURPOSE:To obtain the wiring of high reliability by preventing failures such as disconnection due to causes except electromigration by a method wherein at least one kind of required element is added to an Al wiring, thus setting its width to a fixed value or less. CONSTITUTION:In order to inhibit the formation of a bamboo joint structure formed in the Al wiring, at least one kind of element selected out of Sb, P, and B is added into an Al or Al alloy film at 0.2% or more, thus setting the width of the metallic film approximately at 3mum or less. This manner enables the prevention of failures such as disconnection due to causes except electromigration, and the wiring of high reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to wiring for semiconductors, and particularly to fine wiring having a width and thickness of about 3 μm or less and suitable for improving reliability of semiconductor devices.

[Background of the invention]

Conventionally, disconnection due to electromigration has been the biggest problem regarding the reliability of fine AQ wiring. However, studies conducted by the present inventors have revealed that there are causes of defects such as wire breakage other than electromigration, and that sufficient reliability cannot necessarily be obtained simply by preventing electromigration. Disconnection defects due to such causes have not been reported in the past, and it is expected that this will become a major cause of f7!41 defects as wiring becomes finer in the future. Conventional Aβ or AQ
If alloy is used as material and goes through the current semiconductor manufacturing process,
In a wiring having a width and thickness of 3 μm or less, a structure is formed in which one crystal grain boundary 11 crosses the wiring 10 as shown in FIG. 1 (such a structure is called a bamboo structure). It has been found that in such wiring, defects occur due to causes other than the electromigration described above, and the reliability of the device cannot be ensured.

(Objective of the Invention) An object of the present invention is to solve the above problems, prevent defects such as disconnection due to causes other than electromigration, and provide highly reliable wiring.

[Summary of the invention]

In order to achieve the above object, the present invention prevents disconnection of wiring by making it difficult to form bamboo structures in wiring using conventional materials and manufacturing methods. To this end, in order to suppress the formation of a bamboo structure, it is effective to add an element that inhibits grain growth to AQ to prevent the growth of AQ crystal grains. The addition of this element requires
Two methods can be used: a method in which impurity elements are almost uniformly added to AQ, and a method in which a laminated structure of AQ and an impurity element is created and the impurity element is supplied into AQ by thermal diffusion. Furthermore, the formation of a laminated structure prevents the AQ crystal grain boundary from moving beyond the layer of different atoms, thereby suppressing the formation of structures that suppress coarsening of the crystal grains.

The above element includes at least one of sb, p, or B.
Seeds can be used.

Furthermore, although the above heat treatment is related to both temperature and time, for example, when the time between heat treatments is 1 to 10 hours, the temperature of the heat treatment is approximately 300° C. or less.

The formation of bamboo structures is effectively prevented.

[Embodiments of the invention]

The present invention will be explained in detail below.

Table 1 "5b=0.2~2%"B=0.2~3% *P=0.2~/'% The width of each wiring is 1.0.2.0.2.5. 3.0.4.0
There are 6 types of 5.0 μm thick, 1 μm thick, and 1 m long. FIG. 2 shows the results of determining the proportion of grain boundaries (bamboo structure) that cross the wiring for a length of approximately 100 μm of the wiring by observation using a transmission electron microscope.

Here, the ratio is the ratio of the number of grain boundaries.

As is clear from FIG. 2, when the line width is small, the formation of bamboo structures increases, but this increase in structures is significantly suppressed by the addition of Sb, B, or P.

In addition, after keeping each of the above wirings at 250°C for 1000 hours,
The percentage of wires that were disconnected at grain boundaries was calculated. The number of samples is approximately 100 each.
It is ke. The results are shown in Table 2.

Table 2 The following can be seen from Table 2. (1) The defective rate is particularly high for wirings with a width of 3 μm or less. (11) Since no heat treatment is applied to the same Afi/St wiring, the crystal grain size is small and the ratio of bamboo formation is low, and the defective rate is low. (lit)B,
By adding at least 0.2% or more of P or sb, the defect rate becomes about 1710 or less. By making the crystal grains finer in this way, it is possible to significantly reduce the disconnection failure rate and improve the long-term reliability of the device. It can also be seen that the defective rate can be reduced by reducing the heat treatment.

It has been found that the above Sb, B and P may be added alone as described above, or that two or more of them are equally effective.

Example 2 A film having the structure shown in Table 3 was formed on an Sj substrate whose surface was thermally oxidized, and a wiring pattern was created.

All third surface films were formed by continuous electron beam heating vapor deposition or sputter deposition without breaking the vacuum.

The wiring width was 0.8 μm to 3.6 μm. When these samples were heat treated in an H2 atmosphere at 450"c x 1 hour and the crystal structures of these interconnects were observed using a transmission electron microscope, no bamboo structure was observed in samples #1 to #7 even in the thinnest interconnects.Current quantity In the #8 sample, which is commonly used, a bamboo structure was observed even in the thickest wiring with a width of 3.6 μm.In addition, a two-layer AΩ・2% Si layer formed by temporarily suspending vapor deposition was also observed. Film (film thickness 400 nm/40
0 nm), the crystal structure was similarly observed. As a result, the two-layer film can be distinguished immediately after deposition, but after heat treatment, the boundary between the two layers disappears due to mutual diffusion between the upper and lower layers, and the structure becomes almost the same as that of sample #8, again forming a bamboo structure. , it was found that laminating Al2-8i had no effect.

These wirings were subjected to a 250°C storage test, and the disconnection failure rate after 1000 hours was determined. Sample #8 had a defective rate almost equivalent to that of sample #1 shown in Table 2 of Example 1. No disconnection defects occurred over all wiring widths in samples #1 to #7.

〔Effect of the invention〕

As described above, according to the present invention, the disconnection failure rate of fine interconnects can be reduced by about two orders of magnitude or more, and is therefore extremely useful for increasing the reliability of semiconductor devices using these interconnects.

[Brief explanation of drawings]

Figure 1 is a schematic diagram for explaining the formation of a bamboo structure.
FIG. 2 is a curve diagram showing the effect of the present invention. 1O...A12 alloy wiring, 11...Grain boundary of bamboo structure, 1st mouth release 2)

Claims (1)

[Claims] 1. All that does not include one grain boundary crossing in the width direction
Or wiring made of 11 alloy film. 2. The wiring according to claim 1, wherein the width of the AΩ or AQ alloy film is approximately 3 μm or less. 3. The above AQ or AQ alloy film has sb, p and B
3. The wiring according to claim 1, which contains at least one element selected from 1sty-;z.