In-Line Polishing Liquid Mixing for CMP Uniformity
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Solution Overview
Problem
Conventional CMP devices face issues with aggregation/precipitation and oxidation of polishing liquids in blending tanks, leading to non-uniform slurry concentrations, which affects the polishing process.
Innovation Solution
A polishing liquid supply device with a blending flow channel that mixes slurry and pure water immediately before the CMP device, using mixing units with stirring screws and pressurizing tanks to ensure uniform concentration and prevent liquid stagnation, utilizing flow rate sensors and control mechanisms to adjust the dilution ratio and prevent liquid exhaustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a blending tank with stirring device is used to mix slurry and pure water, then the polishing liquid can be supplied to the CMP device, but the liquid stays in the tank for a long time causing aggregation/precipitation or oxidation, making it difficult to supply uniform slurry concentration
Solution Approach 1:
The patent removes the blending tank from the system and performs mixing directly in the flow channel. The mixing unit is integrated into the flow path, allowing continuous mixing without storage, thereby eliminating the problem of liquid stagnation and maintaining uniform slurry concentration throughout operation.
Solution Approach 2:
The mixing operation is made continuous by integrating the mixing unit into the flow channel. The slurry and pure water are continuously mixed as they flow through the channel, ensuring that the polishing liquid supplied to the CMP device is always at the correct concentration without interruption or stagnation.
2Quantity of substance
If a blending tank is used to store and mix polishing liquid, then the CMP device can receive polishing liquid, but aggregation/precipitation and oxidation occur in the tank, affecting polishing quality
Solution Approach 1:
The patent eliminates the blending tank entirely and replaces it with an in-line mixing unit in the flow channel. This removes the storage function that causes liquid stagnation, aggregation, precipitation, and oxidation, while still providing the necessary mixing function for preparing the polishing liquid.
Solution Approach 2:
The polishing liquid is rapidly mixed and passed through the flow channel without being held in a tank. The continuous flow through the mixing unit and directly to the CMP device minimizes the time the liquid is exposed to conditions that would cause aggregation, precipitation, or oxidation.
3Productivity
If slurry is stored in a drum and pumped through flow channels, then the polishing liquid can be supplied, but liquid exhaustion in the drum can occur, interrupting the polishing process
Solution Approach 1:
The patent prepares the polishing liquid by mixing slurry and pure water in the flow channel just before it reaches the CMP device. This ensures that the polishing liquid is always fresh and at the correct concentration, preventing issues related to liquid exhaustion and maintaining continuous reliable supply.
Solution Approach 2:
The continuous flow system with in-line mixing ensures that slurry is continuously mixed with pure water and supplied to the CMP device without interruption. This eliminates the risk of liquid exhaustion in storage drums and maintains uninterrupted polishing operation.
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 configuration stabilizes the supply of polishing liquids with uniform concentrations, reducing maintenance needs, minimizing chemical attack and particle scratches, and maintaining consistent polishing properties.
Implementation Method 1
a stirring screw in the cylindrical body. It may be configured to mix while stirring the liquids flowing in from the first inflow port and the second inflow port by passing through the stirring screw
Implementation Method 2
one or a plurality of pressurizing tanks provided between the drum in the first flow channel and the branching point
Data Source
AI summary
Provided is technical means capable of supplying a polishing liquid having a uniform slurry flow rate to a CMP polishing device. There is a blending flow channel 40 communicating with a flow channel in which a slurry, ultra-pure water, a chemical, and hydrogen peroxide water are transferred. In this blending flow channel 40, a plurality of types of liquids are blended, and the blended liquid is supplied to the CMP polishing device 8 as a plurality of polishing liquid. A blending tank 52A storing the polishing liquid obtained by blending the liquids is included. A flow channel reaching the CMP polishing device 8 is a circulation flow channel that returns to the blending tank 52A via a branching point 17A from the blending tank 52A toward the CMP polishing device 8.