CMP Retainer Ring Thermoelectric Heat Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) processes experience temperature increases due to friction, leading to erosion and dishing at the edge of wafers, and non-uniform surface polishing, which are not effectively mitigated by existing cooling methods due to the low thermal conductivity of polyurethane polishing pads.
Innovation Solution
Incorporation of a retainer ring with a heat absorbing element, a thermoelectric element, and a heat dissipating element to absorb and dissipate heat generated during the polishing process, using a thermoelectric element to control temperature and a cooling element to efficiently cool the heat dissipating element, thereby reducing temperatures and preventing erosion and dishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling device is arranged in the platen, then the heat during CMP process is lowered, but the heat reduction is ineffective due to low thermal conductivity of polyurethane polishing pad
Solution Approach 1:
A thermoelectric element is introduced as an intermediary between the heat absorbing element (in contact with the wafer) and the heat dissipating element. This thermoelectric element actively transports heat from the polishing pad/wafer interface to the dissipating element, overcoming the low thermal conductivity barrier of the polyurethane material and enabling effective heat removal.
Solution Approach 2:
The passive thermal conduction system (relying on natural heat flow through the polishing pad) is replaced with an active thermoelectric heat pumping system. This substitution enables directional heat transport against the temperature gradient and overcomes the limitations of the polyurethane material's thermal properties.
2Manufacturing precision
If conventional cooling methods are used, then cooling structure is simple, but erosion and dishing occur at the edge of the wafer due to insufficient heat control
Solution Approach 1:
The cooling device is segmented into three functional elements: a heat absorbing element positioned at the wafer interface, a thermoelectric element for active heat transport, and a heat dissipating element for heat rejection. This segmentation allows targeted heat management at different locations, preventing edge erosion and dishing while maintaining polishing uniformity.
Solution Approach 2:
Different regions of the polishing system are given different thermal properties and functions. The heat absorbing element is positioned where heat generation occurs (at the wafer interface), the thermoelectric element provides localized active cooling, and the heat dissipating element is positioned for efficient heat rejection. This local differentiation of thermal management strategies achieves uniform surface polishing.
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 solution effectively reduces temperatures of the polishing pad, wafer edge, and slurry, preventing erosion and dishing, and ensuring a uniform surface polishing rate by efficiently managing heat during the CMP process.
Implementation Method 1
a thermoelectric element disposed in the heat absorbing element
Implementation Method 2
a heat dissipating element disposed on the thermoelectric element to dissipate heat absorbed by the heat absorbing element
Data Source
AI summary
A retainer ring configured to reduce heat generated during a polishing process may include a heat absorbing element, a thermoelectric element, and a heat dissipating element. A polishing head configured to polish a wafer may include a wafer carrier, a retainer ring, and a cooling element. A chemical mechanical polishing apparatus including a polishing pad formed on a platen and a polishing head including a retainer ring.