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The main application and preparation method of titanium silicide

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Update time : 2020-04-26 10:59:43
With the rapid development of ultra-large scale integrated circuits (ULSI), the size of equipment and devices is getting smaller and smaller, and people's requirements for device size and film quality and thickness uniformity are also increasing. At present, the line width of semiconductor devices has been reduced to less than 0.1 μm, and the original process cannot obtain low-resistance continuous wires at this time. New materials, new methods, and new deposition systems must be found to improve or replace aluminum and heavily doped polysilicon for circuit metallization connections. Among these new materials, interest in metal silicides, which have high conductivity and high-temperature stability, and are compatible with current microelectronic manufacturing processes, has increased significantly. Among the currently widely studied metal silicides (such as TiSi2, NiSi, CoSi2, WSi2, TaSi2, MoSi2), titanium silicide (TiSi2) has ideal characteristics: high conductivity, high selectivity, excellent thermal stability, Good adsorption to Si, good process adaptability and low interference to silicon connection parameters. Therefore, in integrated circuit devices, titanium silicide is widely used in metal oxide semiconductor (MOS), metal oxide semiconductor field-effect transistor (MOSFET), and dynamic random access memory (DRAM) gate, source/drain, interconnection and ohm Contact manufacturing.
                           
 
Application of titanium silicide:
 
Titanium silicide is widely used in the manufacture of a metal oxide semiconductor (MOS), metal oxide semiconductor field-effect transistor (MOSFET) and dynamic random access memory (DRAM) gate, source/drain, interconnection, and ohmic contact, examples of its application as follows:
 
1) A titanium silicide barrier layer is prepared. The device using the method for manufacturing the titanium silicide barrier layer includes a non-silicide region and a silicide region separated by an isolation region. The upper surface of the device is covered with a sacrificial oxide layer. The present invention includes: The photolithography process is used to make the photoresist cover the non-silicide area, and the silicide area is exposed; the wet etching process is used to etch away the sacrificial oxide layer of the silicide area; and the silicon exposed in the silicide area is amorphized, As implantation; remove the photoresist remaining in the non-silicide area; sputtering titanium metal for the first alloying treatment; wet etching to remove the unalloyed metal titanium for the second alloying treatment. The invention deletes the silicide block oxide layer in the prior art, reduces the process cost; at the same time, it minimizes the loss of the isolation oxide film by etching and improves the process stability.
 
2) Preparation of an in-situ synthesized titanium silicide (Ti5Si3) particle reinforced aluminum titanium carbide (Ti3AlC2) matrix composite material. By adding a certain amount of silicon, Ti3AlC2 / Ti5Si3 composite materials with different volume ratios were prepared, in which the volume percentage of the titanium silicide particle reinforced phase was 10-40%. The specific preparation method is: first, titanium powder, aluminum powder, silicon powder, and graphite powder are used as raw materials, and the molar ratio of Ti: Al: Si: C is 3: (1.1-x): x: (1.8 ~ 2.0), where x is 0.1 ~ 0.5. The raw material powder is mixed by physical and mechanical methods for 8 to 24 hours, loaded into a graphite mold, the applied pressure is 10 to 20 MPa, sintered in a hot press furnace with a protective atmosphere, the heating rate is 10 to 50 ° C / min, the sintering temperature It is 1400 ~ 1600 ℃, sintering time is 0.5 ~ 2 hours, and sintering pressure is 20 ~ 40MPa. The invention can prepare the aluminum titanium carbide/titanium silicide composite material with high purity and high strength at a relatively low temperature and a short period of time.
                         

3) Preparation of composite functional titanium silicide coated glass. A thin film is deposited on a common float glass substrate, or a thin film of silicon is deposited between them. By preparing a composite film of titanium silicide and silicon or doping a small amount of active carbon or nitrogen in the film to obtain a composite film of titanium silicide composite silicon carbide or titanium carbide or titanium silicide composite silicon nitride or titanium nitride, the mechanical strength and chemical resistance of coated glass have been improved. The present invention is a new type of coated glass that combines the functions of dimming and heat insulation with low-E glass.

 4) 
Preparation of a semiconductor element, including a silicon substrate, a gate, source, and drain are formed on the silicon substrate, and an insulating layer is formed between the gate and the silicon substrate, the gate is located on the insulating layer. The polysilicon layer is composed of a titanium silicide layer on the polysilicon layer. A protective layer is formed on the titanium silicide layer. The protective layer, the titanium silicide layer, the polysilicon layer, and the insulating layer are surrounded by three structural layers, which are nitrogen, in turn, A silicon silicide spacer layer, a parent layer, and a silicon oxide spacer layer, a titanium silicide layer is formed on the source electrode and the drain electrode, an inner dielectric layer is formed on the silicon substrate, and a contact window opening is formed in the inner dielectric layer. By adopting the above technical solution, the utility model can completely insulate the grid and the wires in the contact window without short-circuiting.  
Preparation of titanium silicide
 
Metal silicides can be prepared by physical vapor deposition (sputtering and thermal evaporation, etc.) and chemical vapor deposition (CVD). The purpose of preparing titanium silicide is to obtain TiSi2 with low resistance. TiSi2 has two kinds of polycrystalline phases: metastable C49 phase and thermodynamically stable C54 phase. The C49 phase is an orthogonal bottom-centered crystal system; each unit cell is composed of 12 atoms; the unit cell size is: a = 0.362nm, b = 1.376nm, c = 0.360nm; resistivity ρ = 60 ~ 100μΩ · cm. The C54 phase is an orthogonal face-centered crystal system, and each unit cell is composed of 24 atoms; the unit cell size is: a = 0.826nm, b = 0.480nm, c = 0.853nm; resistivity ρ = 12 ~ 20μΩ · cm [ twenty four]. Since TiSi2 of the C54 phase has a resistivity equivalent to that of the metal body, the purpose of obtaining TiSi2 of the C54 phase is to prepare titanium silicide.

 
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