CMP Exhaust Flow Control for Thermal Management
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Solution Overview
Problem
Conventional methods for controlling temperature in CMP apparatuses, such as thermal contact conductance and dry gas spraying, face challenges in effectively managing heat removal and preventing contamination, leading to inefficient polishing and potential damage to surfaces.
Innovation Solution
An exhaust flow rate control apparatus that adjusts the flow rate of the processing space to maintain a predetermined temperature range by utilizing latent vaporization heat, where air is drawn into the space to facilitate the state change of polishing liquids and remove heat from the polishing pad and wafer surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a cooling plate is placed in contact with the polishing surface to remove heat by thermal conduction, then heat removal effectiveness is improved, but contamination of the polishing pad and slurry occurs due to contact with the cooling plate
Solution Approach 1:
The patent introduces an intermediary cooling mechanism where a cooling fluid (water or water-glycol mixture) flows through channels in the polishing table rather than using direct thermal contact between a cooling plate and polishing pad. This intermediary fluid approach removes heat from the polishing surface through the table structure without introducing contamination from cooling plate contact
Solution Approach 2:
The patent replaces the mechanical thermal contact conductance system (cooling plate physically touching polishing pad) with a fluid-based thermal convection system. Cooling fluid circulates through channels in the polishing table, absorbing heat through convection and conduction from the table structure to the fluid, eliminating mechanical contact contamination
2Temperature
If dry gas is sprayed onto the polishing pad surface to remove latent heat of vaporization, then cooling effect is improved, but slurry splashing occurs reducing polishing effectiveness
Solution Approach 1:
The patent replaces the gas spray evaporation cooling method with a liquid-based convection cooling system. Cooling fluid flows through channels in the polishing table, providing continuous thermal management through convection without the mechanical disruption of gas spraying that causes slurry splashing
Solution Approach 2:
The patent uses hydraulic cooling where fluid flows through channels in the polishing table under controlled pressure. This hydraulic system provides stable, continuous cooling through fluid convection without the pneumatic disruption that occurs with dry gas spraying, maintaining slurry integrity and polishing effectiveness
3Productivity
If pressure is increased or relative velocity is increased to increase polishing rate, then productivity is improved, but frictional heat generation increases causing temperature rise
Solution Approach 1:
The patent implements continuous cooling through constant circulation of cooling fluid through the polishing table channels. This continuous thermal management allows sustained high-pressure and high-velocity polishing operations without temperature accumulation, maintaining both high productivity and controlled temperature
Solution Approach 2:
The system incorporates temperature sensors that continuously monitor polishing surface temperature and provide feedback to the cooling fluid flow control. This feedback mechanism dynamically adjusts cooling intensity based on actual temperature conditions, enabling optimal balance between polishing rate and temperature 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
This approach effectively manages and controls the temperature within a predetermined range, preventing degradation of the polishing pad and maintaining a consistent polishing rate, while avoiding issues like slurry splashing and contamination, thus enhancing the planarity of the polished surface and improving CMP apparatus productivity.
Implementation Method 1
utilizing latent vaporization heat, where air is drawn into the space to facilitate the state change of polishing liquids and remove heat from the polishing pad and wafer surfaces
Implementation Method 2
facilitate the state change of polishing liquids
Implementation Method 3
a cooling plate is placed in contact with the polishing surface of the polishing pad to remove heat therefrom by means of thermal conduction
Data Source
AI summary
The present invention is intended to set the temperature of a predetermined location inside a processing space in which a polishing pad is disposed to within a predetermined temperature range. A substrate processing apparatus includes a CMP apparatus and an exhaust flow rate control apparatus configured to exhaust a polishing space in which the CMP apparatus is disposed. The exhaust flow rate control apparatus is provided with a first exhaust line, a first exhaust flow rate-variable device and an exhaust control unit. The exhaust control unit includes a storage device storing control data on previously-calculated exhaust flow rates necessary to set the temperature of a predetermined location of the CMP apparatus.