JPS5979550A - Manufacture of wiring structure - Google Patents

Abstract

PURPOSE:To obtain a wiring of high reliability by forming an intermetallic compound in uniform and sufficient thickness containing the side surface of an Al wiring, omitting an etching process and simplifying processes while eliminating problems caused by etching. CONSTITUTION:The Al wiring 3 in approximately 1mum thickness is formed on an Si substrate 1 with an SiO2 film 2, WF6+H2 are mixed into N2 gas, and W4 is applied selectively in the thickness of 300Angstrom . Most of W reacts with Al through treatment at 450 deg.C and an intermetallic compound layer is formed to the surface of the wiring 3, and the corrosion resistance and electromigration resistance of the wiring can be improved. Layer thickness coated hardly depend upon directions because of a CVD method, and the side surface of the wiring, particularly, only an Al surface, can also be coated with the metallic layer in uniform and sufficient thickness. Accordingly, a problem to be caused with the removal of a metal being not reacted can be avoided.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing a wiring structure such as an integrated circuit element. This method selectively deposits a different material such as tungsten over the entire surface of the wiring. The properties are further improved when the alloy is formed by heat treatment.

[Prior art]

Although not publicly known, as a prior art, aluminum wiring k
After patterning, there is a technique in which vanadium is vapor-deposited over the entire surface of the substrate, and the temporary, unreacted vanadium formed on the surface of the aluminum wiring by heat treatment is removed. However, this method has the following problems that should be improved. 1) Since the vanadium layer is formed by vapor deposition, the vanadium layer on the side surface of the aluminum wiring is thinner than the top surface of the wiring. Further, depending on the shape of the wiring pattern and the evaporation method used, vanadium may hardly be deposited on the side surfaces. This l-1: The reliability of wiring is completely reduced.

2) There are many steps including vanadium vapor deposition, heat treatment, and removal of unreacted vanadium. 3) It is difficult to remove unreacted vanadium. It is best to perform etching that has sufficient selectivity between intermetallic compounds and unreacted metals and hardly etch the silicon oxide film tongue on the substrate.

[Purpose of the invention]

The purpose of the present invention is as follows. ■) Forming and forming a metal compound layer of uniform and sufficient thickness on the surface of the wiring including the side surfaces, and (2) Simplifying the process by making the etching process a key point, and at the same time eliminating the effects caused by etching. To avoid problems and provide a completely reliable manufacturing method for deep red wiring.

[1 shot of I-Ko] 1) In the chemical vapor deposition method, the thickness of the deposited layer does not depend on the direction. By utilizing this, it is easy to provide a uniform and sufficiently thick metal layer on the side surfaces of patterned aluminum wiring.

2) Furthermore, with this method, the entire metal layer can be deposited only on the surface (including the side surfaces) of the aluminum wiring. Problems associated with removing unreacted metals can therefore be avoided. That is, a second dissimilar metal is formed on the aluminum or aluminum alloy wiring by selective chemical vapor deposition, and then an intermetallic compound layer is formed at the interface thereof.

[Embodiments of the invention] The present invention will be explained below using examples.

Example 1 On a silicon substrate 1 on which a silicon oxide film 2 as shown in FIG. A wiring pattern 3 as shown in the figure was prepared. Tungsten 4 was deposited on this substrate to a thickness of 300 mm by selective chemical vapor deposition as shown in FIG. The case presented was as follows. Nitrogen gas was mixed with reaction gas, tungsten hexafluoride gas, and hydrogen gas and passed to the reaction chamber. Reduce the pressure inside the pipe to approximately 0. When the reaction was carried out while maintaining the temperature at a total temperature of 450 C, it was possible to selectively deposit 300 tungsten particles only on the aluminum surface in 5 minutes. The thickness of the tungsten layer on the side surface of the wiring was almost the same as that on the top surface. After stopping the reaction gas and completely stopping the deposition, continue (2 to 450CQ・-'', stand still for 1 hour,
Alloying of aluminum and tungsten was carried out. Through this treatment, most of the deposited tungsten reacted with aluminum, and an intermetallic compound layer was formed on the surface of the aluminum wiring.

It has been found that the conditions under which tungsten can be selectively grown on aluminum wiring are as follows. Conditions that can be easily controlled include temperature, pressure, hydrogen gas flow rate, and tungsten hexafluoride gas flow rate. Among these, the conditions for selective growth strongly depend on the flow rates of the two gases, hydrogen gas and tungsten hexafluoride gas, and selective growth occurs when the flow rates are within a certain range. In the case of a furnace with a diameter of 10crr1 and a length of 220mm (771) used in the experiment, the following are: Temperature: 450C1 Pressure (carrier gas is nitrogen)
At 0.1 Torr, when the flow rate of tungsten hexafluoride gas is 126 cm3/min, the hydrogen gas flow rate is 10 to 40 cm3/min.
Selective growth occurs in the crn3/min range. When the tungsten hexafluoride gas flow rate is reduced, the range of hydrogen gas flow rate becomes narrower.If the flow rate of tungsten hexafluoride is 3077713/min, the range of hydrogen gas is 10~13c! n3/min. Weak dependence on temperature. When the temperature is lowered, the range of selective growth moves to the side where the hydrogen gas flow rate is large, and the growth rate sharply decreases.

Example 2 By the method shown in Example 1, aluminum whose entire surface was covered with tungsten and aluminum-copper alloy wiring were entirely fabricated. The time (lifetime) for this wiring to run through high-density current until disconnection was measured and compared with wiring without a surface alloy layer. Wiring dimensions are width 2μm, thickness 0.6μm, length 100μm.
1 Also, the current conditions are: temperature 250C x current density 2.5
X 10'A/cm". The results are shown in Figure 4. In the case of aluminum, by providing an alloy layer, the lifespan was extended by 30 to 80 times. In the case of aluminum-copper alloy, the life was also extended by about 15 times. Life expectancy is increasing.

Example 3 The corrosion resistance of the wiring fabricated by the method shown in Example 1 was investigated in the following manner. Chips i, T cut to 3X4 rpm
Silver paste was applied to the o-5 stem, and wires were connected using an ultrasonic bonding method. No noise is provided in the wiring of this chip, and the chip is exposed on the -1 stem. Under conditions of a temperature of 85C and 85% humidity, a full Vides electric field was applied and the time (life) until disconnection corrosion was measured. The average lifespan of aluminum wiring with a surface alloy layer is approximately 900 years.
Value for wiring without surface alloy layer, ■70
A lifespan approximately 5 times longer was obtained.

〔Effect of the invention〕

According to the present invention, as shown in the above embodiments, a long-life At or At alloy wiring Cl structure can be obtained, and its industrial value is extremely large.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are cross-sectional views of a semiconductor element, and FIG. 4 is a diagram showing the energization life of wiring. 1... Silicon substrate, 2... Silicon oxide film, 3.
...A No. 1 Diagram Z Diagram 3 Diagram■ 4 Diagram

Claims (1)

[Claims] In manufactured aluminum or aluminum alloy wiring whose surface is covered with a dissimilar metal or a complete compound of that metal and aluminum, a dissimilar metal, especially a metal that forms an intermetallic compound between it and aluminum, is , forming by a selective chemical vapor deposition method (il- A method for manufacturing an interconnect structure characterized by: