CMP Temperature Control via Radial Fluid Plenum
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes face challenges in temperature control, leading to non-uniformity and variability in polishing performance due to the poor thermal conductivity of polishing pads and non-uniform heat generation across the polishing pad surface, affecting within-wafer and wafer-to-wafer uniformity.
Innovation Solution
A temperature control system with a plenum having openings arranged in a specific pattern to deliver heated or cooled fluid onto the polishing pad, with varying mass flow rates radially to compensate for temperature non-uniformity, allowing for precise temperature control without direct contact, reducing contamination risks and improving process predictability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a solid heat exchange plate is used to control polishing pad temperature, then temperature control is achieved, but contamination of the pad and defects occur
Solution Approach 1:
The patent introduces a fluid (heated or cooled) as an intermediary medium to transfer thermal energy to or from the polishing pad. Instead of direct solid-to-solid contact which causes contamination, the fluid acts as a mediator that can be easily disposed of or recirculated without contacting the pad surface, thus achieving temperature control while avoiding contamination and defects.
Solution Approach 2:
The patent employs a fluid delivery system (hydraulic or pneumatic) to supply heated or cooled fluid to the polishing pad. The fluid is delivered through a plenum with openings positioned over the platen, using fluid dynamics to achieve uniform temperature distribution across the pad surface without mechanical contact.
2Device complexity
If uniform fluid delivery is used across the polishing pad, then simple system design is achieved, but temperature non-uniformity persists
Solution Approach 1:
The patent applies local quality by varying the fluid delivery characteristics across different radial positions of the polishing pad. The plenum includes multiple openings at different radial positions, each delivering a different amount of fluid based on local heat generation requirements. This creates non-uniform fluid distribution that compensates for non-uniform heat generation, achieving temperature uniformity while maintaining reasonable system complexity.
Solution Approach 2:
The patent changes the flow rate parameter of the fluid delivery system across different radial positions. By adjusting the amount of fluid delivered at each radial position, the system compensates for variations in heat generation, achieving temperature uniformity. This parameter adjustment is achieved through strategic placement and sizing of openings in the plenum at different radial positions.
3Device complexity
If temperature control is not implemented, then system simplicity is maintained, but within-wafer and wafer-to-wafer uniformity deteriorate
Solution Approach 1:
The patent incorporates temperature sensing and feedback control. Temperature sensors monitor the polishing pad temperature at multiple radial positions, and this information is fed back to a controller that adjusts the fluid delivery accordingly. This feedback mechanism enables precise temperature control, achieving within-wafer and wafer-to-wafer uniformity while keeping the overall system complexity manageable through automated control.
Solution Approach 2:
The patent performs preliminary temperature control by pre-heating or pre-cooling the fluid before it reaches the polishing pad. The fluid is heated or cooled in advance in a heat exchanger, so that when it is delivered to the pad, it immediately begins to adjust the pad temperature. This preliminary action allows for more efficient temperature control and improves uniformity without requiring complex real-time adjustment systems.
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 solution enables efficient and precise temperature control across the polishing pad, enhancing polishing uniformity and repeatability by reducing temperature variations, thereby improving within-wafer and wafer-to-wafer uniformity and allowing for quick testing and modification of temperature profiles.
Implementation Method 1
a plenum having a plurality of openings positioned over the platen and separated from the polishing pad for delivering the fluid onto the polishing pad
Implementation Method 2
By quickly and efficiently raising or lowering temperatures across the surface of a polishing pad
Implementation Method 3
a source of heated or coolant fluid and a plenum having a plurality of openings positioned over the platen and separated from the polishing pad for delivering the fluid onto the polishing pad
Data Source
AI summary
A chemical mechanical polishing apparatus includes a rotatable platen to hold a polishing pad, a carrier to hold a substrate against a polishing surface of the polishing pad during a polishing process, and a temperature control system including a source of heated or coolant fluid and a plenum having a plurality of openings positioned over the platen and separated from the polishing pad for delivering the fluid onto the polishing pad, wherein at least some of the openings are each configured to deliver a different amount of the fluid onto the polishing pad.