Independent Electron and Ion Energy Distribution Control for Semiconductor Processing

Statement of the problem or situation that is being addressed in your application. The ability to use plasma etching to produce high aspect ratio (HAR) features is becoming increasingly important as the market demands solid-state non-volatile memory storage. To minimize defects in HAR features and produce higher aspect ratio features, precision and independent control of the ion and electron energy angular distribution functions (IEAD and EEAD) is required. Additionally, HAR etching requires longer processing time and higher etch rates are needed to reduce overall cost, which requires higher power systems. General statement of how this problem is being addressed. EHT is developing an industrially relevant bipolar pulse generator that allows for independent control over the positive and negative pulses. The system would consist of two separate waveforms alternately applied, with one waveform optimized to produce the desired IEAD and the second to produce the desired EEAD. To commercialize this power system in the semiconductor capital equipment market, independent control must be validated experimentally and connected with improved etching results. What is to be done in Phase I? The goal of the SBIR program is to develop an understanding of the complex power system-plasma dynamics through a combined experimental and computational program. In the Phase I program, EHT will modify the existing plasma chamber to enable use of electronegative plasmas (similar to those used in the semiconductor industry), demonstrate the ability to make EED measurements, and begin to investigate bipolar pulsing for IED/EED control. On the computational side, an existing model will be modified for the EHT conditions and validated. The baselined model then enables us to explore the plasma-power system connection on a time and length scale that would be challenging or impossible to measure experimentally. Additionally, the modelling will allow us to connect the plasma-power system effects with the IEAD/EEAD and ultimately to etch results. Commercial Applications and Other Benefits The market for solid-state, non-volatile memory storage is driving the demand for NAND flash. To overcome some of the challenges with manufacturing 2D NAND, the semiconductor processing industry has largely transitioned to 3D NAND, which requires precision etching of HAR features with aspect ratios exceeding 100:1. Improved control of the IEAD and EEAD improves the quality of HAR features. HAR etching requires longer processing time and higher etch rates are needed to reduce overall cost. EHTĺs new bipolar pulse generator for wafer bias has the potential to provide independent control of the IEAD and EEAD to improve the quality of HAR features while operating at the high power required to increase etching rates thereby reducing production time, lowering costs and increasing yield.