JPS6161264B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a semiconductor device, and particularly to metal materials for electrode portions and wiring. Recently, as semiconductor integrated circuits have become more highly integrated and faster, the selection of gate electrodes, wiring materials, etc. has become a major problem. Conventionally, polysilicon, aluminum, etc. have been used as gate electrode and wiring materials. However, the resistance value of polysilicon is higher than that of metals such as aluminum.
Since the speed was about 100 times higher, there was a problem in increasing the speed of the device. Also, since aluminum has a large crystal grain size, there is a problem in making the pattern finer. There were also other problems, such as large electromigration and lack of reliability of the semiconductor element. Therefore, recently, high-melting point metals (metals with melting points of 1400°C or higher, hereinafter referred to as metals), such as molybdenum and tungsten, which can be microfabricated and can withstand high-temperature heat treatment, have received renewed attention. This kind of technology is described in the US monthly magazine "Electrochemical Society".
“Self-Registered Molybdenum-Gate” in “Society” (August 1968 issue)
MOSFET)” (pages 874 to 876). However, these metals are extremely difficult to handle because they are easily oxidized even at temperatures as low as 400°C. Furthermore, it has the property of reacting with silicon to form silicide at low temperatures around 500°C, resulting in an increase in wiring resistance, or due to the difference in volumetric expansion and thermal expansion between silicide and silicon. Peeling occurs,
Alternatively, it has disadvantages such as increased contact resistance of the semiconductor element. Therefore, when molybdenum or tungsten is used as a wiring material, an added condition is that the substrate temperature should not be raised above 500 to 600° C. after the metal is attached to the silicon substrate. Therefore, not only are the original features of high-melting point metals not fully utilized, but they are also severely restricted in the production of semiconductor devices. To avoid these problems, it becomes necessary to deposit a barrier metal to prevent reactions between metals such as molybdenum, tungsten, etc. and the silicon substrate, resulting in a multilayer structure. However, this method not only has the disadvantage of complicating the process because it requires precise control of the film thickness, but also makes etching of multilayer metals particularly complicated and difficult for finer patterns. This is not a very desirable method. In addition, there have recently been reports of the use of molybdenum silicide or tungsten silicide deposited by sputtering as electrode and wiring materials. For example, the Electrochemical Society Full Meeting was held in the fall of 1977 in the United States.
``A New Gate Materials'' by ``Mical Society Fall Meeting'' (1977)
Devices, Molybdenum Silicide (MOS I2) (A New Gate Material
For Mos Devices, Molybdenum Silicide
(MoSi ₂ )” (pages 871 to 873). However, these also have problems such as higher resistance values than metals. SUMMARY OF THE INVENTION An object of the present invention is to provide an improved semiconductor device in view of the above-mentioned conventional method. This is particularly effective when manufacturing. The features of the present invention are that by adding rhenium to molybdenum metal, which has been conventionally used as an electrode and wiring material, it has strong oxidation and corrosion resistance, suppresses the formation of silicide, and has small recrystallized grains. An object of the present invention is to obtain a semiconductor device equipped with an alloy film having certain characteristics. Next, the present invention will be explained with reference to photographs. FIG. 1 is a photograph taken obliquely from above in the vicinity of the main surface of a cross section of a semiconductor device manufactured by a conventional technique, using a secondary electron image of a scanning electron microscope. FIG. 2 is a photograph of the vicinity of the main surface of a cross section of a semiconductor device manufactured according to the present invention taken from diagonally above using a secondary electron image using a scanning electron microscope. (The size of each part of the semiconductor device observed in the photographs shown in Figures 1 and 2 is determined by assuming that the vertical and horizontal lengths of these photographs are approximately 1.5 μm, and the dimensions are proportional to this length.) ) Here, the semiconductor device shown in the photograph in Figure 2 is
A metal 5 made of molybdenum doped with 2.5 atomic% rhenium is deposited on a silicon substrate 6, and then heat treated at 1000°C for 30 minutes.
It has a smooth surface 4. However, the first
Since the semiconductor device shown in the photograph in the figure is simply molybdenum deposited on a silicon substrate 3 and subjected to heat treatment, all of the deposited molybdenum becomes silicide 2. Further, this silicide 2 has an uneven surface 1. Therefore, not only the specific resistance is high, but also volume expansion has occurred, and many cracks or peelings 7 are observed in some areas. In comparison, as shown in the photograph of FIG. 2, the semiconductor device according to the present invention is extremely stable even on a silicon substrate, with almost no silicide being formed. This fact suggests that the resistance value of the deposited film retains the original value of the metal even after high-temperature heat treatment, as will be described later. In other words, this shows that this is a method that can fully utilize the inherent characteristics of high-melting point metals. Furthermore, as can be seen from FIG. 2, the recrystallized grain size is approximately 50 nanometers (nm), making it most suitable for semiconductor devices that require miniaturization. Furthermore, the alloy film according to the present invention has superior oxidation resistance, corrosion resistance, and temperature coefficient compared to metals such as molybdenum and tungsten, so it is extremely superior in terms of process and reliability. It can be said that it has certain properties. Furthermore, in terms of processability, patterning is possible without any problems if plasma etching or ion milling methods are applied. Based on the present invention, an alloy film is formed on a silicon thermal oxide film and a silicon substrate, and then heated at 1000°C for 30 minutes.
The following table shows the results of a comparison between the resistivity of the sample subjected to the heat treatment for 1 minute and that of the molybdenum sample formed by the prior art.

[Table] The specific resistance of the alloy film formed based on the present invention is 16
×10 ^-5 Ω・cm, which is approximately
Although the value is 2.5 times higher, when heat treated at 1000℃, the resistivity based on the present invention becomes 1.6×10 ^-5 Ω・cm, which is 1/10 of the value immediately after adhesion. is decreasing. This value is approximately the same as that of a molybdenum film heat-treated under the same conditions. On the other hand, when deposited on a silicon substrate, the alloy film based on the present invention exhibits almost the same behavior as on an oxide film, whereas the resistivity of a molybdenum film after heat treatment is 4 times higher than that based on the invention. This is due to the formation of silicide. It has also been revealed that the adhesion of the alloy film according to the present invention to the silicon oxide film is on the same level as that of a single metal such as molybdenum. The above results are an example of an alloy film in which 2.5 atomic% rhenium is added to a molybdenum film.
A similar effect can be obtained by varying it from 0.1 to 50 atomic%. As described above, alloy films obtained by adding molybdenum and rhenium, which are metals for metallization, can be used as electrodes or wiring materials for semiconductor devices to increase the degree of integration of semiconductor devices.
This produces effects such as higher speed and higher reliability.

[Brief explanation of the drawing]

FIG. 1 is a photograph taken obliquely from above in the vicinity of the main surface of a cross section of a semiconductor device manufactured by a conventional technique, using a secondary electron image of a scanning electron microscope. FIG. 2 is a photograph of the vicinity of the main surface of a cross section of a semiconductor device manufactured according to the present invention taken from diagonally above using a secondary electron image using a scanning electron microscope. In the figure, 1...the surface of the silicide, 2...
...Silicide, 3...Silicon semiconductor substrate, 7...
. . . cracks or peeling, 4 . . . surface of molybdenum-rhenium alloy film, 5 . . . molybdenum-rhenium alloy film, 6 . . . silicon semiconductor substrate.

Claims (1)

[Claims] 1. In a semiconductor device equipped with an electrode wiring etc. formed of a material containing molybdenum on a semiconductor substrate, the material containing molybdenum is 0.1 to 50 atomic%.
A semiconductor device characterized by being made of a molybdenum alloy material containing rhenium.