| As metal oxide semiconductor field-effect transistors（MOSFET）continue to develop toward miniaturization,Si-based MOSFETs have been aggressively scaled-down several times and are approaching their physical limit.More recently,germanium（Ge）has attracted a great deal of interest as a channel material in high-performance transistors,due to the high hole and electron mobility.The potential application of germanium in future metal oxide semiconductor field-effect transistors has led to the active exploration of suitable germanide,owing to its low resistivity,low formation temperature,and feasibility for self-aligned germanidation process.Nickel germanide（Ni Ge）has been selected as the most promising contact material for Ge-based MOSFET devices.However,the traditional thermal annealing process is difficult to control the junction depth of the source and drain regions due to slow heating and cooling and long heat treatment time.Even though rapid thermal annealing（RTA）can alleviate this problem due to its rapid heating and short heating time,as the process size is further reduced,the conventional RTA cannot meet the requirements due to its high thermal budget.Although the new ultra-rapid annealing process（such as laser annealing）can achieve a lower thermal budget,the spot size is small which will take a great deal of time to cover the entire surface area of the sample.Recently,microwave annealing has attracted more and more attention from researchers due to its rapid heating,good temperature control performance,selective heating,overall heating,energy-saving,and high efficiency.The major work of this paper is to use a microwave annealing method to study the solid-phase reaction process of nickel（Ni）and germanium（Ge）as follows aspects:（1）The effect of microwave annealing at different temperatures on the formation of Ni Ge is studied.It has been found that under the mediation of Ti interlayer,planar and uniform Ni Ge films can be prepared on Ge（100）substrates by microwave annealing.In addition,during the formation of Ni Ge,the Ti intermediate layer becomes an ideal covering layer on the top of Ni Ge after Ni-Ge reaction,thus further protecting the contact performance of Ni Ge.（2）The influence of different substrates under low-temperature microwave annealing on the Ni Ge film formation is investigated.It is found that,as the formation of high-quality Ni Ge thin films,the microwave annealing temperature of Ni/Ti/Ge samples on P-type Ge substrate is 250℃,and that of Ni/Ti/Ge samples on intrinsic Ge substrate is 350℃.The microwave annealing temperature of the P-type germanium substrate sample is 100℃ lower than the annealing temperature of the intrinsic germanium substrate sample,which may be caused by the difference of conductivity between them. |
