In-line metrology of nanoscale features in semiconductor manufacturing systems

- This paper presents a system for rapid inspection of nanoscale features.
- The system consists of a single-chip AFM, flexure-based positioning stage, and passive wafer alignment stage.
- The single-chip AFM is capable of scanning a 15 μm × 15 μm area with vertical resolution of 0.48 nm.
- The overall wafer in to wafer out cycle time of the system is less than 1 min.
- Miniaturization of moving parts has enabled high throughput scanning with single-chip AFMs.

Quality control and defect monitoring are of great importance to the semiconductor industry. This article presents a system to enable inspection of nanoscale features in-line with nanomanufacturing processes. The ultimate goal of this research is to integrate this metrology system into current semiconductor manufacturing processes to enable true in-line wafer inspection and quality control. In the system presented in this paper, AFMs that have been shrunk down on to a single MEMS chip are used to scan the surface of a sample. A flexure-based mechanism allows the MEMS-based AFM to be positioned over a millimeter range of motion, with nanometer level precision when properly actuated. The performance of the system in areas such as positioning repeatability, AFM stability and measurement resolution are evaluated in this study. Owing to the small size of single-chip AFM (1 million times smaller than a conventional AFM instrument), it is a good candidate for multipoint detection. Overall, the system presented in this paper significantly shortens inspection time and dramatically decreases the setup time required for an AFM to load, approach, and measure a sample making in-line inspection of nanoscale features in semiconductor manufacturing systems feasible.