Sun Mingren

Effect of plasma density on the distribution of incident ions and depth profile in plasma-based ion implanted layers

Abstract The retained dose and compositional depth profile were studied in the context of cylindrical target with different plasma density treated by plasma-based ion implantation (PBII). Nitrogen was implanted into silicon wafer clamped on the samples in order to acquire high quality profiles. Auger electron spectroscopy (AES) was used to acquire the nitrogen depth profile at the middle of Si wafer. A method, that combined fluid dynamic model to simulate plasma sheath expansion during high voltage pulse and TRIM code to simulate incident ion distribution in the solid was presented to simulate the experimental results. Both retained dose and N depth profile were compared with the results of theoretical simulation. The agreement between them for all three cases is good; that is, the model can give a good prediction and explanation to the experimental results. The retained dose for cylinder increases with increasing plasma density. The continuously distributed energy of incident ions and low N + /N 2 ratio in the plasma shift the N depth profile nearer to the surface and reduce the range significantly.

Simulation of the distribution of incident ions and depth profile in plasma-based ion implanted layers with different pulse width

The implantation dose and compositional depth profile were studied in the context of cylindrical target with different pulses treated by plasma-based ion implantation. Nitrogen was implanted into silicon wafer clamped on the samples in order to acquire high-quality profile. Auger electron spectroscopy was used to acquire the compositional depth profile at the middle of the Si wafer. The measured results, both implantation dose and depth profile, were compared with the results of theoretical simulation. A method, that combined fluid dynamic model to simulate the sheath expansion and TRIM code to simulate incident ion distribution in the solid was presented. The agreement between the measured results and theoretical calculations for all three cases is good. The implantation dose for the cylinder is increased with increase in pulse width, which is consistent with theoretical prediction. The continuously distributed energy of incident ions and N2+/N+ ratio in the plasma shift the depth profile nearer to the surface and reduce the projected range significantly.

Microstructure and properties of Nb/Ta multilayer films irradiated by a high current pulse electron beam

Nb/Ta multilayer films deposited on Ti6Al4V substrate with Nb and Ta monolayer thicknesses of 30 nm, 120 nm, and 240 nm were irradiated by a high current pulse electron beam (HCPEB) to prepare Nb—Ta alloyed layers. The microstructure and the composition of the outmost surface of melted alloyed layers were investigated using a transmission electron microscope (TEM) equipped with an X-ray energy dispersive spectrometer (EDS) attachment. The Ta content of the alloyed surface layer prepared from the monolayer of thickness 30 nm, 120 nm, and 240 nm was ~ 27.7 at.%, 6.37 at.%, and 0 at.%, respectively. It was found that the Ta content in the alloyed layer plays a dominant role in the microstructure of the films. The hardness and the wear rate of the alloyed layers decrease with the increasing content of Ta in the surface layer.

Measured and calculated retained dose with different process parameters in plasma based ion implantation

This paper reports the research that systematically studied the effect of the adjustable process parameters on the retained dose in plasma based ion implantation with an aim to provide a method for optimizing the implantation process. Nitrogen was implanted in a silicon wafer clamped on a cylindrical sample holder while varying parameters such as implantation voltage, radio frequency (RF) power, pulse width and target size. Auger electron spectroscopy was used to execute sputter depth profiling and to obtain the retained dose at the middle of the silicon wafer. The retained dose on the wafer was also predicted using fluid dynamic model, which simulates the sheath dynamic mode with consideration of the sputtering effect of the implanted ions. The measured results were compared with theoretical calculations, and the agreement for all the samples was good. The implantation dose for the cylinder will increase with increasing implantation voltage, pulse width or the RF power. A larger sample will result in a decreased dose, although the large ion reception area will push the sheath edge to a further position from the substrate.