What Is CMP?
CMP, chemical mechanical polishing, is a technology used for precision polishing of semiconductor wafers in large scale integration (LSI) and micro electro-mechanical systems (MEMS).
This process, requiring nanometer-level precision, smoothens surfaces to an extremely fine degree, achieving angstrom-level surface smoothness. It combines mechanical and chemical processes by applying a chemical abrasive on a polishing pad to polish the substrate surface.
Advanced technology and expertise are essential in CMP equipment, polishing pads, and abrasives to achieve such precision.
Uses of CMP
CMP is critical in semiconductor device manufacturing, polishing substrates like silicon wafers. It is also used in MEMS substrates, glass substrates for displays, HDDs, and solar cell production. CMP’s precision makes it vital for producing high-performance semiconductor chips and displays.
Principles of CMP
CMP involves three key elements: polishing abrasives, chemical agents, and a polishing pad.
1. Polishing Abrasives
These are in liquid or slurry form, containing abrasive particles. The abrasive type varies depending on the substrate material and desired finish.
2. Chemical Agents
Chemical agents assist abrasives in smoothing the surface. They include oxidants, reducers, additives, and solvents like water or alcohol.
3. Polishing Pad
The pad is mounted on a rotating table larger than the substrate. During polishing, the substrate is pressed against the pad while both rotate in opposite directions.
After polishing, the substrate undergoes cleaning and inspection for surface flatness and roughness.
How to Choose CMP
Choosing CMP involves either building an in-house line or outsourcing to a specialized company.
1. In-House Line Construction
In-house CMP requires selecting suitable equipment, designing processes, maintaining systems, and training engineers.
2. Outsourcing to Specialized Companies
Outsourcing involves selecting a company that can provide comprehensive CMP services, including equipment and process development.