JPH0215631A - Al wiring part in semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of a hillock by a method wherein the maximum Al wiring width between an Al wiring part and an Al alloy wiring part in a semiconductor device and the mean grain size of Al in the case where an Al thin film is formed by a vacuum deposition method are set in a specified relation. CONSTITUTION:When the mean grain size of Al in the case where an Al thin film is formed by a vacuum deposition method is assumed to be d(ev), the maximum Al wiring width W between an Al wiring part and an Al alloy wiring part in a semiconductor device is within an extent of W<=5Xd(ev) and when the mean grain size of Al in the case where the Al thin film is formed by a sputtering method is assumed to be d(sp), the maximum Al wiring width W is within an extent of W<=50Xd(sp). In such a way, the wiring width between the Al wiring part consisting of an Al film and the Al alloy wiring part consisting of an Al alloy film in the semiconductor device is controlled by the mean grain size of Al. By limiting the absolute quantities of the distortions of the films and the absolute quantity of a grain boundary which is regarded as an active point of the generation of a hillock by a wiring width, the generation of a hillock is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to Al wiring for semiconductor devices that can prevent hillocks, and is applicable to polycrystalline silicon thin film transistors in general.

[Conventional technology]

In recent years, as semiconductor devices have become more highly integrated, multi-layer wiring has progressed in metal wiring technology, while large-area devices such as thin film transistor devices, in which polycrystalline silicon is deposited on an insulating substrate, have been developed as a new technological field. It's coming.

Along with this, the problem of hillock occurrence in wiring Alff4 has been brought into focus.

In other words, in a multilayer wiring metal structure, one layer metal/
Interlayer leakage due to hillocks in interlayer films/two-layer metals has had a negative impact on device yield and reliability. In addition, large-area devices, such as sensor drive TPTs, liquid crystal panels, and EL panel drive TPTs, are commonly completed by forming a device on the upper layer after forming a thin film transistor section. be. Therefore, similar to the multilayer wiring metal structure described above, there are problems in that failures and defects such as interlayer leakage occur due to hillocks.

As measures to prevent the occurrence of such hillocks, An alloy,
That is, several percent of Si and Cu are added to Al.

A method is known in which an Al alloy film is obtained by forming an alloy of T x + M g or the like by magnetron sputtering. For example, J, Vac, Sci, Tec
hnol, A5 (4), July/Aug1987゜” 5ubstrate Tell1perature
Dependence of Hillock, Gr.
ain, and Crystal○rientatio
nin 5 puttered A 12-alloy
Atoms of a different type than Al, which is an alloy component, are unevenly distributed at the grain boundaries of Al grains, and when Al recrystallizes due to the thermal history of the process, for example, alloy atoms
In this case, the intermetallic compound of Cu A Q is crystallized and grain boundary growth is hindered, and as a result, it helps prevent hillocks.

[Problem to be solved by the invention]

However, when using an Al alloy film as a wiring material, there are the following problems. That is, contact resistance increases, etching residue is produced in the etching process, and after-corrosion tends to occur, resulting in poor reliability. Furthermore, alloy films produced by sputtering are susceptible to slit-like cracks due to stress micro-crash (causing disconnection of interconnects), which becomes an even more serious problem in large-area thin film transistors.

Therefore, the present invention can prevent the occurrence of hillocks due to thermal history when Al or Δα alloy is used as a wiring material, improve process yield and reliability, and provide Al wiring for semiconductor devices that solves the above-mentioned problems. The purpose is to provide

[Means to resolve the problem]

In the present invention, in order to achieve the above object, the maximum AlQ line width W of Al and An alloy wiring in a semiconductor device is
If the Afl average crane size when the pancreas is formed by vacuum deposition method is d (ev), then W≦5Xd (e
v), and if the AlQ average crane size when the Al thin film is formed by sputtering is d (sp), then W≦50Xd (sp).

In this way, in the present invention, Al and Al in the semiconductor device
The wiring width of the alloy film is regulated by the AlQ average crane size. Namely.

When forming an Al or AlQ gold thin film by vacuum evaporation method,
Assuming that the Al average queen size is d (eV), the maximum wiring width W is designed in the range of W≦5Xd (eV), preferably in the range of WS2.8Xd (eV). In addition, when forming an Al or AlQ gold thin film by sputtering, and assuming that the AlQ average crane size is d (sp), W is in the range of W≦50×d (sp), preferably W≦20×d (sp). Design within the range of.

This prevents the occurrence of hillocks by limiting the absolute amount of strain in the film and the absolute amount of grain boundaries, which are active sites for hillock generation, by line width.

Parts where large currents flow, such as power lines in semiconductor devices,
It is possible to design multiple wires by using the Afl maximum wiring width mentioned above. The Al wiring is designed to have a current density of 10' A/cd or less, but this increases the maximum arrangement width of ΔQ mentioned above. In this case, the problem can be solved by using a plurality of wirings each having a width of W or less.

Next, examples will be shown.

Example: Al film was deposited by vacuum evaporation method at substrate temperature, room temperature (25°C), 10
The film was formed at 0°C and 200°C, and the Al film was deposited using magnetron sputtering at the substrate temperature in a room @ (25°C) and 200°C.

The film was formed at 400°C and A
Q-0.5 Ut% Cu alloy film was deposited at substrate temperature and room temperature (25
℃), 200°C, and 400°C.

After that, the wiring width was changed to 2 μm, 5 μm, 10 μm, and 20 μm.
and patterned by photolithography etching to a length of 3000 μm, and heated at 450°C and 60°C.
The hillock density and size (diameter) were determined using an optical microscope, and the crane size was determined using an SEM (Scanning Electron
It was determined from microscopic images.

Among these, the hillock density is shown in FIG. 1, and the crane size is shown in FIG. 2 in relation to the substrate temperature. these,
In FIGS. 1 and 2, (a) shows Al by vacuum evaporation, and (b) shows Al by magnetron sputtering.

And (C) is AQ- by the Macnetron sputtering method.
The case where 0.5wt% Cu was formed into a film is shown. And the first
In the figure, circles indicate the case where the wiring width is 20 μm, and square marks indicate the case where the wiring width is 10 μm.

From these FIGS. 1 and 2, it can be seen that the larger the crane size, the smaller the hillock density. Furthermore, no hillock was observed in any of the samples with a wiring width of 5 μm or less.

[Action/effect of the invention]

As described above, in the present invention, when the maximum wiring width W is manufactured by vacuum evaporation method and sputtering method, W≦50×d
(even and W≦50Xd(sp), so hillocks in Afl wiring are completely prevented,
Process yields are improved, and the reliability of semiconductor devices is also improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between substrate temperature and hillock density when Al and Al alloy are formed into films by vacuum evaporation and Macron sputtering. FIG. 2 is a diagram showing the relationship between substrate temperature and crane size when Al and Al alloy are formed into films by vacuum evaporation and magnetron sputtering.

Claims (1)

[Claims] 1. Maximum Al of Al and Al alloy wiring in semiconductor devices
If the wiring width W is the average crane size of Al when the Al thin film is formed by vacuum evaporation method, then W≦
5 x d(ev), and the average Al crane size when the Al thin film is formed by sputtering method is d(
An Al wiring for a semiconductor device, characterized in that, where W≦50Xd(sp), the range is W≦50Xd(sp).