Micro-layer CMP Polishing Subpad Edge Uniformity
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes face challenges in achieving uniform planarization across semiconductor wafers, particularly at the edges, leading to yield losses due to edge fast or edge slow removal rates.
Innovation Solution
A CMP polishing pad with a polymeric matrix and a porous subpad structure, featuring a nonporous microlayer for secure adhesion, a single layer of closed cell micropores for compressive force transition, and a multilayer of gas-filled closed, open, or mixed cell micropores to distribute pressure and prevent slurry wicking, enhancing wafer yield and edge uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP polishing pads are used, then global planarization can be achieved, but edge fast or edge slow removal rates occur leading to yield losses
Solution Approach 1:
The polishing pad incorporates a nonporous microlayer at the periphery and a porous subpad at the center, creating different functional zones. The microlayer controls edge removal rate by preventing slurry wicking and providing consistent contact pressure, while the porous subpad allows slurry penetration for effective polishing at the wafer center, thereby eliminating edge effects and improving overall planarization uniformity
Solution Approach 2:
The polishing pad combines two distinct material structures: a nonporous microlayer made of solid polymer material and a porous subpad with interconnected pore structure. This composite construction allows each layer to perform its specific function - the microlayer for edge control and the subpad for bulk material removal - resulting in improved manufacturing precision and wafer yield
2Stability of the object's composition
If polishing pad compressibility is increased to improve conformality, then edge effects worsen due to uneven pressure distribution
Solution Approach 1:
The nonporous microlayer at the periphery provides a consistent, non-compressible contact surface that maintains uniform pressure distribution across the wafer edge, preventing edge fast or slow removal rates while the porous subpad at the center provides necessary compliance for conformal contact
3Productivity
If slurry flow rate is increased to improve polishing rate, then edge fast removal rate occurs
Solution Approach 1:
The nonporous microlayer acts as an intermediary barrier at the periphery that controls slurry access to the polishing interface. By preventing excessive slurry penetration at the edges while allowing adequate slurry flow through the porous subpad at the center, the microlayer mediates between high polishing rate requirements and uniform edge removal rate control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described polishing pad design improves wafer yield by reducing edge effects and maintaining consistent performance throughout the polishing process, ensuring uniform planarization and increased deflection for more efficient polishing.
Implementation Method 1
a single layer of closed cell micropores adjacent the nonporous microlayer for transitioning compressive forces from the bottom surface of the polishing pad to the porous subpad
Implementation Method 2
a multilayer of closed cell, open cell or a mixture of closed and open cell micropores adjacent the single layer of closed cell micropores wherein the multilayer of closed cell, open cell or a mixture of closed and open cell micropores are gas filled and the multilayer of closed cell, open cell or a mixture of closed and open cell micropores remains gas filled during an entire polishing life of the polishing pad
Implementation Method 3
a porous subpad adhered to the bottom surface of the polishing pad, the porous subpad including: a nonporous microlayer
Data Source
AI summary
The polishing pad has a polymeric matrix, a polishing surface useful for polishing at least one of semiconductor, magnetic and optical substrates and a bottom surface; a porous subpad adhered to the bottom surface of the polishing pad. The porous subpad includes a nonporous microlayer for securing the polishing pad to the porous subpad. The porous polymer network contains i) a single layer of closed cell micropores adjacent the nonporous microlayer for transitioning compressive forces from the bottom surface of the polishing pad to the porous subpad; and ii) a multilayer of closed cell, open cell or a mixture of closed and open cell micropores adjacent the single layer of closed cell micropores.