Study On The Detection Method Of Amorphous Damage Layer Of Silicon Sub-Surface Based On The Selective Etching Of Hf Solution

Due to the rapid development of highly integration and functionalization of semiconductor products, it has been proposed strictly requirement for the surface machining quality for semiconductor materials, such as single crystalline silicon. Previous investigations indicated that the amorphization in the subsurface region is the main damage in the earlier stage of ultra-precision machining process of single crystalline silicon. Therefore, quantitative detection of the amorphous layer is of great importance for the evaluation of damage at the (sub)surface region of silicon. At present, there are several available methods in the market, which can be used for analysis of amorphous layer on silicon surface. Although these methods can analyze the mechanical, chemical or structural properties of the material surface, there are some bottlenecks for these methods, such as the complicated procedure for sample preparation, long period or expensive cost for the detection. Therefore, it is necessary to search a precise, fast and economic way to detect the properties of amorphous layer at silicon surface.Since previous investigations indicated that the subsurface damage layer of silicon could be selectively etched in HF solution, we proposed a rapid detection method to detect the thickness of sub-surface damage layer of silicon in present thesis. The validity of the method was verified by TEM analysis. Based on the proposed method, the thickness of damage layer of silicon subsurface was detected at different applied load and sliding speed.The main conclusions and innovative points could be summarized as follows:(1) Based on selective etching behavior of HF solution, a precise and rapid detection method was proposed to detect the thickness of amorphous layer at the subsurface of silicon. TEM analysis indicated that the subsurface amorphous layer could be selectively etched off in HF solution. Such results confirmed the validity of the method. This method is expected to be applied for the detection and control of the subsurface damage of silicon during wafer planarization process.(2) A new method was proposed to measure the density of amorphous layer at subsurface of silicon. The weight of amorphous layer could be measured by comparing the weight before and after the etching experiment, and its volume could be estimated by a professional software. Thus, the density of amorphous layer could be evaluated by the equation.(3) The effect of applied load and sliding speed on the subsurface damage of scratched region of silicon was studied. It was found that when the applied load was below 1.1 times of the critical yield load of silicon material, the thickness of damaged subsurface of scratched region decreased as the sliding speed increased. However, when the applied load was larger than 1.8 times of the critical yield load of silicon material, the thickness of damaged subsurface of scratched region would not change with the sliding speed.