Research On Source And Drain Ohmic Contact Resistance Of Ge MOSFET

We are living in an era that electronic information industry develops rapidly,and the microelectronics industry is the backbone of the electronic information industry.In the past few decades,the application of semiconductor materials represented by silicon has enabled the IC industry to develop rapidly.However,with the development of technology,the size of semiconductor devices has become smaller.Traditional materials are facing limitations in technical and physical.Simply shortening the channel length to improve the integration of integrated circuits and improve the performance of semiconductor devices has become more and more difficult.In order to improve the performance of the device,it is necessary to find a new semiconductor material to make up the shortcomings of silicon materials.Because Ge has higher electron and hole mobility than Si,and Ge are compatible with Si semiconductor device processes,it is the ideal candidates.There are many factors have influence on the performance of semiconductor devices and the resistance is an important factor.The resistance of a semiconductor device is composed of material body resistance and contact resistance in source and drain.When the size of the semiconductor device is large,the contact resistance in source and drain accounts for a small proportion of the total device resistance,and has little influence on the performance of the semiconductor device.However,as the device size becomes smaller,the contact resistance of the semiconductor device source and drain.The contact resistance accounts for an increasing proportion of the entire device resistance,and the influence on the performance of the semiconductor device is also increasing.In order to reduce the contact resistance on the source and drain electrodes of semiconductor devices and improve the performance of semiconductor devices,we have studied the ohmic contact resistance of Ge or Ge Sn with metals from several different aspects.At first,we studied the effect of heavy doping on the contact resistance of metal and semiconductor.In the experiment,we used the control variable method.Taking a piece of Ge,half of which was heavily doped as the experimental group and the other was not doped as the control group.The experimental results show that heavy doping has an important influence on the contact resistance of metals and semiconductors.Then we studied the effect of different metal materials on the contact resistance of metal and semiconductor materials.In the experiment,the metals Ni and Ti were selected as the contact metals for comparative.Under the same experimental conditions,the results show that Ni is more suitable as a contact electrode for Ge and Ge Sn materials.Finally,we are supposed to find the most suitable annealing temperature when metal is in contact with Ge and Ge Sn materials.Choosing the appropriate annealing interval and setting different annealing temperatures,we have obtained the following conclusion: The optimal annealing temperature for p-Ge contact is 400?,the optimum annealing temperature of n-Ge,n-Ge Sn and p-Ge Sn contact is 350?.These experimental results have important guiding significance for forming good ohmic contact and improving the performance of the device.In the above experiments,we found that the contact resistivity between n-Ge and metal materials is higher than p-Ge.It is because of the Fermi pinning effect in Ge.Due to the Fermi pinning effect,ordinary ion implantation is difficult to obtain a high concentration of P+ in Ge,and since P+ is easily diffused at high temperatures in Ge,n-Ge contact with low contact resistivity has been a challenge.This paper proposes a new experimental scheme to reduce the diffusion of P+ on the Ge.We use ion implantation,contact formation,and ion re-implantation to make the diffused P+ regains a higher concentration at the contact interface,thereby reducing the contact resistance between metal and Ge.The experimental results show that this method has a significant effect on reducing the n-Ge contact resistance,and the contact resistance of the n-Ge and Ni is reduced to one-sixth of the original.