Abstract
The accuracy of ion implantation is very important in semiconductor manufacturing and will directly affect the performance of the individual devices and even the whole chip. The deviations of ion implantation energy, dose and angle often result from abnormality of implant equipment or process design limit. The information of ion implantation energy, dose and angle can be qualitatively and quantitatively analyzed by SIMS (Secondary Ion Mass Spectrometry) [1], which provides a way to diagnose ion implanter issue. Based on SIMS analysis results, we can judge whether ion implanter meets the requirements and whether the process design achieves the expected goal. In this paper, we report a SIMS data analysis method determine the deviation of ion implantation angle. A term of deviation rate is defined and a related calculation method was introduced, which is proportional to the deviation angles of the ion implanter. Then, a statistical analysis on a large number of data of deviation rates and ion implantation angles showed that the sampling data followed normal distribution, and thus the corresponding 3 sigma could be obtained. Using the determined 3 sigma range of the deviation rates, we can define the acceptable range for deviation rate. Further, we can use the actual deviation rate to judge if the implant equipment needs maintenance or not, or suggest the direction for improvement. Finally, we set up an oriented and quantitative optimization method of angle deviation by the full mapping of SIMS depth profiles, which can directly set the relationship between the angle deviation and the adjustment parameters of ion implantation disk (Δ alpha, Δ beta). The equipment’s maintenance time and cost can thus be minimized. This method can be used as early detection to the abnormity of ion implant equipment.
