JPS63278254A - Wiring material of aluminum alloy - Google Patents

Abstract

PURPOSE:To obtain a material for a target which causes few defects due to heat by a method wherein a wiring material is formed by an evaporated film containing aluminum and a prescribed alloy constituent. CONSTITUTION:A wiring material is formed by an evaporated film containing more than 95 wt.% of aluminum and less than 5 wt.% of an alloy constituent which is composed of 2 mol of boron and 1-2 mol of a group VIa metal of the periodic table. This wiring material of an aluminum alloy is supplied as a material for a target. Because the melting point of this material for the target is about 3000 deg.C, the material can become a crystalline nucleus when the aluminum is solidified and, accordingly, a very fine crystal is expected. In addition, because this material is an intermetallic compound and becomes big as a block of a molecule, a movement of an aluminum atom during a heat treatment during the supply of an electric current; accordingly, the crystal growth and the formation of various migrations and hillocks are improved. It is, therefore, possible to prevent a defect from being caused during a wiring process of a multilayer film and to enhance the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] Industrial Application Field The present invention relates to a target material used in means such as sputtering vapor deposition and a target used in means such as electron beam vapor deposition to form wiring for semiconductor integrated circuits, etc. It relates to materials and films formed using the same.

Conventional technology A vapor-deposited film of aluminum or an aluminum-based alloy is formed to form wiring in semiconductor integrated circuits, etc.
Etching and then heat treatment are performed to remove internal strain and form ohmic contact with the silicon substrate.

If such wiring is made of aluminum, electromigration may occur when electricity is applied, changing the characteristics of the board, or changing the cross-sectional area of the wiring, making it more likely to break. Alloys containing small amounts of both are often used. Such a vapor-deposited film of an aluminum alloy is preferably used because it is less prone to the so-called hillock phenomenon, in which aluminum crystals grow abnormally and protrude from the film surface during heat treatment, and electromigration when electricity is applied. However, as semiconductors become more highly integrated,
Even in such conventional vapor-deposited aluminum alloy films, the occurrence of defects has become impossible to ignore.

Problems to be Solved Due to the above-mentioned circumstances, there is a demand for a vapor deposited film for forming interconnections with even fewer defects, and the present invention aims to provide a target material for forming a vapor deposited film that can meet such demands. .

In other words, an object of the present invention is to minimize the occurrence of heat-induced defects even when a vapor-deposited film obtained by sputtering, electron beam, etc. is subjected to heat treatment, and to have physical properties suitable for wiring and electrodes, and excellent etching properties. It is an object of the present invention to provide a target material for sputtering or electron beam for forming a vapor deposition film for wiring and a film that exhibits chemical properties such as:

What is thought to be a particular problem in the future is the so-called bamboo phenomenon caused by hillocks and crystal coarsening that occur after heat treatment.

[Structure of the invention] Means for solving the problem The physical or chemical properties necessary to solve the above problem can be summarized as follows.

That is, A9. and A (S contained in the base material)
When i is etched with H (JL gas), it needs to be a substance that is etched at the same time and preferably scatters in the form of scraps.

The target material for vapor deposition of the present invention is 90 to 99.99% by weight of aluminum or an aluminum-silicon alloy containing 10 times less silicon and 0.0% by weight of titanium boride, zirconium boride, or hafnium boride compound.
The materials used in the sputtering process, consisting of 1-10% by weight, aluminum or aluminum alloys for conventional integrated circuits (AI-8iAl-S, -C,A (L-Cc
etc.) Materials used in sputtering processes consisting of 90-99.99% by weight and 10-0.01% by weight of titanium boride, zirconium boride, hafnium boride, and aluminum or aluminum alloys for conventional integrated circuits 5
It is a material used in the electron beam method, consisting of 0 to 99% by weight and 50 to 1% by weight of a metal boride belonging to group IV-a of the periodic table.

To prepare the target material of the present invention, aluminum or conventional integrated circuit aluminum alloy wiring material (A
When melting and producing alloys such as Kano-sz, AI-S, '-CL, An C1, boron and periodic table IV-
Metals of group a are simultaneously dissolved in an atomic ratio of 1:1 or close to 1:2, preferably boron and IV of the periodic table.
-A metal is melted and pulverized in advance at the appropriate atomic ratio, then melted together with the base material aluminum or aluminum alloy, alloyed, cast, processed into the required shape, and used as a target material. .

Effect The target material for vapor deposition of the present invention obtained as described above contains aluminum or an aluminum alloy containing Group IV-a of the periodic table and boron either singly or in the form of an intermetallic compound and has a melting point much higher than that of aluminum. high, about 3
．． Since it is around 0OO0Q, it can become a crystal nucleus during solidification of aluminum, so very fine crystals are expected. In addition, since it is an intermetallic compound, it becomes large in molecular units and prevents the movement of aluminum atoms during heat treatment or when electricity is applied, resulting in crystal growth and various migrations.
Hillrock formation is improved.

Among conventional alloys, aluminum-silicon-copper alloys containing copper are highly effective in inhibiting crystal growth, migration, and hillock formation, and this effect was increased by increasing the copper content.

However, as the copper content increases, the copper is converted into a non-volatile substance such as copper chloride against the etching that occurs in subsequent processes, which tends to reduce the reliability of the resulting integrated circuit. On the other hand, in the alloy of the present invention, the hagelonides of boron and the hagelonides of metals of group IV-a of the periodic table, which are thought to be generated by dry etching, are volatile and therefore have an adverse effect on the reliability of integrated circuits. There's nothing wrong with that.

It is inevitable that the effects of these alloys will increase as the content of the additives related to the present invention increases, but on the other hand, the electrical conductivity will decrease significantly and the etching properties will also change. It is not practical for the total amount of added metals in the thin film to exceed 5% by weight once it is formed as a thin film.

In the case of a thin film of 5% by weight, the sputtering target material may be any alloy containing approximately the same weight%, but in the case of an electron beam material, for a film composition of 5% by weight, the boride according to the present invention Although it varies depending on the shape and weight of the device and material, it corresponds to about 50% by weight at most.

Example 1 0.5% by weight of titanium boride (TLB) pre-alloyed to 99.5% by weight using a low uranium, thorium concentration aluminum alloy containing 1% by weight of silicon as a base material
A plate-shaped sputtering target was manufactured by blending and melt-casting.

Sputtering deposition was performed on a silicon wafer using a processed and shaped sputtering target of 6'φ×5t to form an aluminum alloy deposited film with a thickness of about 1 mm. The sputtering conditions were ~10 Torr substrate heating at 200''C, sputtering power at 2KW high frequency, and magnetron method.

Next, the silicon wafer on which the aluminum alloy vapor deposited film was formed was annealed at 450'C in a 20 m + Nz atmosphere, and the results before and after the annealing treatment were compared using an electron microscope and a surface roughness meter. A conventional aluminum-silicon alloy was also subjected to the same treatment under the same conditions and compared. As a result, Hillrock, which was measured using a 3,000x magnified photograph, was compared to the conventional aluminum product.
In the case of the silicon alloy, there were almost zero particles before annealing, but the number increased to 85 after annealing. On the other hand, in the alloy containing titanium boride of the present invention, the number was 6 after annealing and zero before annealing.

The results measured by a surface roughness meter also produced almost the same results.

Example 2 3% by weight of pre-alloyed titanium boride (T, B2) was blended with 97% by weight of a material made of a low uranium and thorium aluminum alloy base material containing 2% by weight of silicon and melted. A plate-shaped sputtering target was manufactured by casting.

As a result of conducting the same test under the same conditions as in Example 1, the number of hillocks was zero before the annealing process, but decreased to two after the annealing process. No difference was found using a surface roughness meter before and after annealing.

Example 3 Using 95% by weight of a 99.999% pure aluminum alloy containing 11% by weight of silicon as a base material, zirconium and boron were weighed at an atomic ratio of 1:2 to give a total of 5% by weight. Then, a master alloy was produced by arc melting, and an alloy according to the present invention was produced by vacuum melting to produce an electron beam target material. A tablet with a diameter of 20 mm and a thickness of 10 mm was made by processing, and an aluminum alloy film of 1 μm was formed on a silicon wafer using an electron beam. As a result of performing the same test as in Example 1 on the formed aluminum alloy film, it was confirmed in an electron micrograph that the number of hillocks, which were zero before annealing, was 10 after annealing.

[Effects of the Invention] The target material for vapor deposition of the present invention and the alloy film formed by vapor deposition are used as wiring forming materials in semiconductor integrated circuits, etc. When the film is vapor-deposited on a silicon substrate, internal strain is removed by heat treatment and ohmic contact is achieved. Since abnormal crystal growth that occurs when the process is completed does not occur, hillocks in the planarization process in the fabrication of semiconductor integrated circuits, especially hillocks, are minimized, thereby preventing the occurrence of defects in the multilayer wiring process and increasing reliability.

Claims (2)

[Claims] (1) An aluminum alloy wiring material comprising a vapor deposited film containing 95% by weight or more of aluminum and 5% by weight or less of an alloy component consisting of 2 moles of boron and 1 to 2 moles of a metal belonging to Group 4A of the periodic table. (2) 97% by weight or more of aluminum, 5% by weight or less of a first alloy component consisting of 2 moles of boron and 1 to 2 moles of a metal belonging to Group 4A of the periodic table, and boron and a metal belonging to Group 4A of the periodic table. An aluminum alloy wiring material comprising a vapor deposited film containing 4% by weight or less of a second alloy component that does not contain any metal belonging to the above.