Research Progress on Chemical Vapor Deposition for Contact Hole Processes

Abstract

Contact holes are critical interconnect structures in semiconductor devices, and the shape and composition of the materials that fill their interiors significantly impact devices performance. Traditional deposition methods like physical vapor deposition have been replaced by chemical vapor deposition due to the poor step coverage capability. However, depositing contacts with high aspect ratios becomes increasingly challenging as device dimensions shrink. As a result, the manufacturing processes impose higher demands on chemical vapor deposition technologies for material deposition. This paper explores the development of deposition techniques for filling vias. It first introduces tungsten CVD, which is the most widely used. Besides, it presents further advanced techniques such as atomic layer deposition and selective deposition. This paper analyzes the principles, advantages, and limitations of these techniques. After that, it compares their differences in cost and other aspects. Finally, it presents the other application scenarios of these CVD techniques. The conclusion points out that tungsten CVD can improve the device performance by depositing thinner barrier layers through atomic layer deposition. Nevertheless, selective deposition eliminates the need for these layers, thus resolving high-resistance issues fundamentally. Selective deposition is a key technique for overcoming contact resistance bottlenecks.