Polishing Pad Temperature Control via Spiral Flow Passages
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Solution Overview
Problem
Conventional pad-temperature regulating apparatuses for CMP processes experience significant temperature fluctuations, leading to inconsistent polishing rates due to the time required to switch between hot and cold water supplies, resulting in large overshoots and undershoots in surface temperature control.
Innovation Solution
An apparatus and method that utilize a pad contact member with spiral heating and cooling flow passages, allowing simultaneous flow of heating and cooling liquids, with independent flow rate control based on the polishing pad's surface temperature, maintaining a stable target temperature by controlling the flow rates of the liquids through dedicated supply pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hot water or cold water is selectively supplied to the pad contact member by closing one valve and opening another, then the surface temperature of the polishing pad can be regulated, but large overshoot and undershoot occur causing significant temperature fluctuations
Solution Approach 1:
The patent applies preliminary action by pre-heating or pre-cooling the water in the supply pipes before it reaches the pad contact member. Temperature adjustment mechanisms are placed in the supply lines upstream, so the water is already at the desired temperature before contact with the polishing pad, preventing temperature overshoot and undershoot.
Solution Approach 2:
The patent introduces an intermediary thermal mass (the water in the supply pipes) that is pre-adjusted to the target temperature. This intermediary carries the temperature adjustment function away from the direct contact point, allowing smooth temperature transitions without fluctuations when switching between heating and cooling modes.
2Temperature
If the liquid supply is switched from hot water to cold water to cool down the pad contact member, then the surface temperature can be reduced, but it takes a certain amount of time causing large overshoot
Solution Approach 1:
The system performs preliminary temperature adjustment of the water in the supply pipes before it reaches the pad contact member. By the time the water arrives at the contact member, it is already at the target temperature, eliminating the delay associated with heating or cooling the water in-transit.
Solution Approach 2:
The patent maintains continuous temperature control by ensuring that both hot and cold water supplies are continuously available and pre-adjusted. This eliminates interruptions and delays in the temperature control action, allowing immediate response when temperature adjustments are needed.
3Temperature
If conventional valve switching control is used to regulate pad temperature, then temperature control is achieved, but the surface temperature fluctuates greatly with variations of about 20°C
Solution Approach 1:
The water in the supply pipes is pre-adjusted to the exact target temperature before reaching the pad contact member. This preliminary adjustment eliminates the need for rough valve switching control, achieving precise temperature control without fluctuations of about 20°C.
Solution Approach 2:
The patent incorporates temperature sensors and control mechanisms that continuously monitor the water temperature in the supply lines and adjust it to match the target temperature. This feedback control ensures that only water at the precise target temperature reaches the polishing pad, eliminating large temperature variations.
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 enables stable maintenance of the polishing pad's surface temperature at a desired target, reducing temperature fluctuations and ensuring consistent polishing rates by analog-like temperature control, preventing hunting and maintaining uniformity.
Implementation Method 1
passing a heating liquid and a cooling liquid simultaneously through a heating flow passage and a cooling flow passage, respectively, while placing a pad contact member in contact with a surface of the polishing pad
Data Source
AI summary
There is disclosed an apparatus which can maintain a surface temperature of a polishing pad at a desired target temperature. The apparatus for regulating a surface temperature of a polishing pad, includes: a pad contact member which is contactable with a surface of the polishing pad and which has a heating flow passage and a cooling flow passage formed therein; a heating-liquid supply pipe coupled to the heating flow passage; a cooling-liquid supply pipe coupled to the cooling flow passage; a first flow control valve attached to the heating-liquid supply pipe; a second flow control valve attached to the cooling-liquid supply pipe; a pad-temperature measuring device configured to measure a surface temperature of the polishing pad; and a valve controller configured to operate the first flow control valve and the second flow control valve based on the surface temperature of the polishing pad.