CMP Wafer Heater Thermal Gradient Reduction
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Solution Overview
Problem
Chemical mechanical polishing processes face inefficiencies due to thermal gradients between the wafer and polishing pad, leading to potential thermal shock and prolonged transient stages, which affect the material removal rate and overall efficiency.
Innovation Solution
The implementation of a chemical mechanical polishing apparatus that heats both the wafer and polishing pad to matching temperatures before contact, utilizing thermal sensors and controllers to maintain a consistent thermal environment, along with a slurry heater to ensure optimal chemical reaction conditions, minimizes thermal gradients and enhances the material removal rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer and polishing pad are brought into contact without pre-heating, then the apparatus structure is simpler, but thermal gradients cause thermal shock and prolonged transient stages reducing polishing efficiency
Solution Approach 1:
The wafer and polishing pad are pre-heated to matching temperatures before contact through separate heating systems. The wafer is heated on a heated carrier head, while the polishing pad is heated by a heating element behind the pad structure. This preliminary thermal conditioning eliminates thermal gradients at contact, preventing thermal shock and reducing the transient stage duration, thereby improving polishing efficiency without compromising structural simplicity
Solution Approach 2:
The patent changes the thermal parameters of both the wafer and polishing pad before contact by introducing independent heating systems. The wafer temperature is controlled via a heated carrier head with temperature sensors, while the polishing pad temperature is controlled by a heating element positioned behind the pad. This parameter matching ensures both components reach optimal temperatures before interaction, eliminating thermal shock and improving material removal rate
2Use of energy by moving object
If thermal gradients are maintained during polishing, then less energy is consumed for heating, but thermal shock occurs affecting wafer integrity and polishing quality
Solution Approach 1:
Energy is consumed efficiently by pre-heating both the wafer and polishing pad to matching temperatures before contact, rather than attempting to heat them differentially during polishing. The wafer is heated on a heated carrier head, and the polishing pad is heated by a heating element behind the pad structure. This preliminary action ensures thermal equilibrium at contact, preventing thermal shock and protecting wafer integrity while maintaining reasonable energy consumption
Solution Approach 2:
Temperature sensors monitor the thermal state of both the wafer and polishing pad, providing feedback to control systems that adjust heating elements accordingly. This feedback mechanism ensures both components reach and maintain matching temperatures, preventing thermal gradients that would cause thermal shock to the wafer while optimizing energy consumption by avoiding unnecessary heating
3Speed
If the polishing process starts without thermal equilibrium, then the process initiation is faster, but the transient stage is prolonged reducing overall material removal rate
Solution Approach 1:
Both the wafer and polishing pad are pre-heated to matching temperatures before contact through independent heating systems, achieving thermal equilibrium rapidly at the start of the process. The wafer is heated on a heated carrier head, while the polishing pad is heated by a heating element behind the pad structure. This preliminary thermal conditioning eliminates the prolonged transient stage, allowing immediate stable polishing and maximizing material removal rate from the outset
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 reduces the risk of thermal shock, shortens the transient stage, and increases the overall efficiency of the polishing process by maintaining a consistent temperature across the wafer, polishing pad, and processing chamber, resulting in a higher and more stable material removal rate.
Implementation Method 1
a wafer heater (120) disposed in the processing chamber and configured to heat the wafer
Implementation Method 2
a pad heater (150) disposed in the processing chamber and thermally connected to the polishing pad (200), the pad heater (150) configured to heat the polishing pad (200)
Implementation Method 3
a slurry heater (190) configured to be thermally connected to the slurry (400) and configured to heat the slurry (400)
Implementation Method 4
The polishing action is partially mechanical and partially chemical. The mechanical elements of the process apply downward pressure while the chemical reaction that takes place increases the material removal rate
Implementation Method 5
at least one of the carrier head (130) and the platen (115) is rotated, causing the wafer (300) and the polishing pad (200) to rub against each other
Data Source
AI summary
A chemical mechanical polishing (CMP) apparatus includes a processing chamber, a platen, a wafer heater and a carrier head. The platen is disposed in the processing chamber and is configured to allow a polishing pad to be disposed thereon. The wafer heater is disposed in the processing chamber and is configured to heat a wafer. The carrier head is disposed in the processing chamber and is configured to hold the heated wafer against the polishing pad.