Pattern Wafer CMP Endpoint Detection Using Orientation Scan Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes face challenges in reliably detecting the endpoint due to variations in material thickness and types on patterned semiconductor substrates, making it difficult to accurately determine when the polishing process is complete.
Innovation Solution
The method involves using a controller to position sensors, a carrier head, and a platen in consistent orientations relative to each other, scanning the substrate surface during polishing, and comparing the generated scan data to library data to adjust the polishing process and determine the endpoint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CMP processes use a sensor disposed in a polishing platen to detect the endpoint, then the polishing process can be monitored, but the detection reliability deteriorates due to variations in material thickness and differing material types on patterned semiconductor substrates
Solution Approach 1:
The system performs preliminary actions by determining substrate orientation before polishing begins, and by pre-processing sensor data to compensate for orientation effects. This allows the endpoint detection to account for varying material thickness and types at different substrate locations, improving both accuracy and reliability of endpoint detection across patterned semiconductor substrates
Solution Approach 2:
The system changes the parameter of substrate orientation determination and incorporates it into the endpoint detection process. By adjusting detection parameters based on substrate orientation and material distribution, the system maintains reliable endpoint detection despite variations in material thickness and types across the substrate surface
2Ease of operation
If the substrate is polished without controlling orientation, then the polishing process is simpler to operate, but the manufacturing precision deteriorates due to inability to distinguish material removal from structural artifacts
Solution Approach 1:
The system replaces manual orientation control with an automated optical or metrology-based orientation determination system. This substitution maintains ease of operation by automating the process while simultaneously enabling precise endpoint detection through correlation of sensor data with known substrate orientation and material distribution patterns
3Measurement precision
If sensors scan the substrate surface during polishing, then the endpoint detection capability is improved, but the device complexity increases due to additional orientation control and data processing requirements
Solution Approach 1:
The system achieves multi-functionality by using the same sensor system for both orientation determination and endpoint detection. The sensor serves dual purposes: establishing substrate orientation at the beginning and monitoring material removal during polishing, thereby improving endpoint detection precision without proportionally increasing device complexity
Solution Approach 2:
The system introduces data processing algorithms as an intermediary that correlates sensor scan data with substrate orientation information. This intermediary layer enables precise endpoint detection by distinguishing material removal signals from structural artifacts, while keeping the physical hardware complexity manageable through software-based solutions
Data Source
AI summary
In one embodiment, a method of processing a substrate in a chemical mechanical polishing (CMP) system, comprises determining an orientation of a substrate relative to a first carrier head. The method further includes initiating a polishing process of a surface of the substrate engaged with a polishing pad. The method further includes scanning, during the polishing process, a first portion of the surface of the substrate repeatedly using at least one endpoint sensor coupled to the polishing pad to generate orientation dependent scan data of a property of the first portion of the surface. The method further includes comparing the orientation dependent scan data to a library of orientation dependent scan data to determine when the endpoint of the polishing process has been reached.