Dynamic Temperature Control for CMP Dishing and Erosion
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Solution Overview
Problem
The non-planar surface of substrates during integrated circuit fabrication poses challenges in photolithography, leading to impaired light focusing and the need for periodic planarization. Chemical mechanical polishing (CMP) is used for planarization, but it faces issues with temperature control affecting polishing rate and uniformity.
Innovation Solution
A chemical mechanical polishing system with an in-situ monitoring system and a temperature control system, where the controller adjusts the temperature of the polishing process based on signals indicative of the amount of material on the substrate, thereby controlling dishing and erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If temperature is increased to maintain polishing rate, then productivity is improved, but dishing and erosion worsen
Solution Approach 1:
The patent implements dynamic temperature control by modulating the temperature of the polishing pad or substrate during the polishing process. The temperature is adjusted based on real-time monitoring of polishing conditions, material thickness, or process stage, transitioning from static to dynamic control to simultaneously maintain high polishing rates and minimize dishing and erosion
Solution Approach 2:
The patent changes the temperature parameter during polishing by heating or cooling the polishing pad, substrate, or slurry. This parameter modification allows optimization of polishing rate at higher temperatures while reducing dishing and erosion through temperature reduction, achieving both productivity and precision goals
2Manufacturing precision
If temperature is decreased to reduce dishing and erosion, then manufacturing precision is improved, but polishing rate decreases
Solution Approach 1:
The patent employs periodic temperature modulation during polishing, alternating between higher temperature phases for material removal and lower temperature phases for surface quality control. This periodic action allows the system to achieve both high overall polishing rates and minimal dishing and erosion through cyclic temperature variations
Solution Approach 2:
The patent applies preliminary heating before polishing to enhance material removal rate, then reduces temperature during critical polishing stages to minimize dishing and erosion. This preliminary action at high temperature followed by temperature reduction achieves both productivity and precision objectives
3Device complexity
If conventional temperature control is used, then device complexity is minimized, but polishing uniformity worsens
Solution Approach 1:
The patent implements feedback control by monitoring polishing process parameters such as material thickness, polishing rate, or surface quality and using this information to dynamically adjust temperature. This feedback mechanism improves polishing uniformity while maintaining reasonable system complexity through intelligent control algorithms
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 system effectively controls dishing and erosion, improves polishing uniformity, and maintains or increases throughput by modulating the temperature of the CMP process in response to real-time substrate conditions.
Implementation Method 1
The temperature control system may include an infrared heater to direct heat onto the polishing pad, a resistive heater in the support or carrier head
Implementation Method 2
a thermoelectric heater or cooler in the support or carrier head
Implementation Method 3
a heat exchanger configured to exchange heat with a polishing liquid before the polishing liquid is delivered to the polishing pad
Data Source
AI summary
A chemical mechanical polishing system includes a support to hold a polishing pad, a carrier head to hold a substrate against the polishing pad during a polishing process, an in-situ monitoring system configured to generate a signal indicative of an amount of material on the substrate, a temperature control system to control a temperature of the polishing process, and a controller coupled to the in-situ monitoring system and the temperature control system. The controller is configured to cause the temperature control system to vary the temperature of the polishing process in response to the signal.