Electrical Properties Of Ta₂O₅High Dielectric Films And Stability Of The Device

In order to adapt to the rapid development and large scale integrated circuit,we continue to shrink the size of the device characteristrics.When device features size reduced to less than65nm,the traditional silica dielectric layers gate the thickness of the need to less than1.4nm, and so thin layer of silicon dioxide will greatly increase the power consumption of the device, and abate grid voltage control the ability of the channel. In the equivalent oxidation layer thickness remains the same, by the use of high dielectric material replace traditional grid of medium, medium thickness of the physical layer increased use of method, can significantly weakened direct tunneling effect, and increase the reliability of the device. So, looking for high dielectric medium material of the gate became a top priority. In the high dielectric gate medium material, the Ta2O5both has high dielectric constant (K-26), and can be compatible with the traditional silicon process, and that’s supposed to be in a new generation of dynamic random access memory (DRAM) capacitors in a material is quite a potential replacement. So, Ta2O5preparation and their performance film, strong practical value, has aroused people’s attention.This paper using RF sputtering method (RF) preparation five oxidation2tantalum gate medium film, a deep research annealing temperature and temperature on the grid work medium electrical influence on the performance of the film, and the effect on the stability of to the device.This thesis mainly the research content as follows:1. The different annealing temperature on Ta2O5film the influence of electrical properties. The results showed that the temperature of400℃annealing, leakage current density of the film is the largest. This is because the annealing temperature mainly in two aspects of leakage current, on the one hand, the annealing temperature increase process, also is the film from the amorphous into a more the process of crystal, along with the enhancement of crystallization, leakage current density get bigger; On the other hand in the annealing temperature increase of the process, oxidation silicon interface layer thickness will increase and decrease leakage current density, in the two aspects of the common role in400℃with film the largest leakage current density. Annealing temperature of600℃, the leakage current density smaller films. This is because in the annealing temperature of the process, oxidation layer of the capture charge will slowly disappear, all kinds of defects in the body will be reduced, and then the film leakage rheological small.2. The different working temperature of f Ta2O5film electrical performance influence. Work with the increase of temperature, film the leakage current density increase gradually. But, in a lower temperature (such as80～100K), leakage current increases rapidly. That there are two main influence factors, one is the interface between the generation of silicon oxide layer will promote the increase of leakage current, on the other hand is the sample defects will increase leakage current.3. The stability of the research to the device. To different annealing temperature treatment samples on Constant pressure, measuring its work under different temperature, leakage current changes with time rule. Results show that, just add voltage (time is0～2s), abandoned the leakage is sharply, as time continuous leakage current will not change. This is mainly due to the beginning, in the defect and under the influence of electron trapping make leakage current change sharply; Along with the continuous voltage applied, charge to a dynamic balance of migration, leakage current will no longer happen apparent change.