CMP Slurry Mixing Control for Stable Oxidizing Power
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) processes face challenges in dynamically adjusting the slurry mixing ratio based on process conditions, leading to inefficiencies and waste due to pre-prepared slurry instability and batch preparation.
Innovation Solution
A CMP apparatus with integrated storage tanks for hydrogen peroxide, DI water, and additives, along with flow rate control units and a mixer, allows for real-time adjustment of the slurry mixing ratio and flow rate within the apparatus, ensuring optimal slurry preparation directly for the polishing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If slurry is prepared in advance using batch preparation method, then the polishing process can be maintained, but the slurry mixing ratio cannot be adjusted dynamically and waste occurs due to instability
Solution Approach 1:
The patent implements dynamic slurry preparation by replacing the static batch preparation method with a continuous mixing system. The mixer continuously combines slurry stock solution with oxidizing agents (hydrogen peroxide and/or ozone) and additives at adjustable ratios, allowing the slurry composition to be dynamically adjusted according to real-time process conditions rather than being fixed in advance.
Solution Approach 2:
The system changes the concentration parameters of the slurry by controlling the flow rates of various components (slurry stock solution, hydrogen peroxide, ozone, additives) through flow rate control units. This enables precise adjustment of the oxidizing power and composition of the slurry to match different polishing requirements, resolving the contradiction between adaptability and waste.
2Reliability
If slurry is pre-prepared, then the polishing process can proceed, but oxidizing power deteriorates over time leading to quality issues
Solution Approach 1:
The system performs preliminary preparation of the slurry stock solution separately from the oxidizing agents. The slurry stock solution is prepared in advance and stored stably, while the oxidizing agents (hydrogen peroxide and/or ozone) are added continuously just before use. This preliminary separation allows the base slurry to be prepared without degradation, while the oxidizing power is maintained fresh through continuous addition.
Solution Approach 2:
The continuous mixing system ensures that the slurry is continuously replenished with fresh oxidizing agents and additives, maintaining consistent oxidizing power throughout the polishing process. This continuous action prevents the deterioration that occurs in batch-prepared slurry, ensuring reliable polishing quality over extended periods.
3Adaptability or versatility
If fixed ratio slurry preparation is used, then the system is simple, but it cannot adapt to different polishing process conditions
Solution Approach 1:
The slurry preparation system is segmented into separate functional units: a slurry stock solution supply unit, oxidizing agent supply units (hydrogen peroxide and/or ozone), additive supply units, and flow rate control units for each component. This segmentation allows independent control and adjustment of each component's flow rate, enabling adaptation to different process conditions while keeping each individual unit relatively simple.
Solution Approach 2:
The continuous mixing system serves multiple functions: it prepares the slurry stock solution, mixes in oxidizing agents and additives at variable ratios, controls flow rates, and supplies slurry to the polishing pad. This multi-functionality allows a single integrated system to handle different polishing process conditions without requiring separate preparation systems for each condition.
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 precise control over the slurry composition and quantity, reducing waste and maintaining optimal oxidizing power, thus improving the CMP process efficiency and substrate polishing quality.
Implementation Method 1
a mixer connected to the plurality of flow rate control units and configured to mix a slurry stock solution, the hydrogen peroxide, the DI water, and the additive with each other to prepare a slurry having a predetermined flow rate
Implementation Method 2
a plurality of flow rate control units configured to control a flow rate of the hydrogen peroxide, the DI water, and the additive
Implementation Method 3
a slurry supply unit configured to draw out the slurry stored in the slurry storage unit and to supply the slurry to a polishing pad
Data Source
AI summary
A chemical mechanical polishing apparatus includes: supply pipes to which a slurry stock solution and a diluent are supplied; flow rate control units, respectively disposed on the supply pipes to control flow rates of the slurry stock solution and the diluent; a mixer connected to the flow rate control units and configured to mix the slurry stock solution and the diluent, supplied from the supply pipes, to prepare a slurry; a slurry storage unit connected to the mixer and configured to store the slurry prepared in the mixer; a slurry supply unit configured to draw out the slurry stored in the slurry storage unit and to supply the slurry to a polishing pad; and a control unit configured to control the flow rate control units to control a mixing ratio of the slurry stock solution and the diluent and a flow rate of the slurry to the polishing pad.