Retaining Ring Negative Tapered Surface for CMP
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Solution Overview
Problem
Conventional CNC machining methods produce retaining rings with rough surfaces and inadequate flatness, leading to inefficient polishing processes and high capital and labor costs due to the need for extensive break-in procedures.
Innovation Solution
A retaining ring with a negative tapered sacrificial surface and a conditioning fixture that applies a lateral load to form a smooth, flat surface, allowing for efficient polishing and reducing particle generation during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CNC machining methods are used to manufacture retaining rings, then manufacturing simplicity is maintained, but the surface roughness and flatness are inadequate for efficient polishing
Solution Approach 1:
The patent applies preliminary action by pre-conditioning the retaining ring sacrificial surface before actual polishing operations. The conditioning fixture with tapered surface and applying apparatus prepares the surface in advance to achieve the required flatness and roughness, eliminating the need for extensive break-in procedures during production polishing runs.
Solution Approach 2:
The patent introduces an intermediary conditioning fixture that mediates between the conventional machining process and the polishing process. This fixture with its tapered conditioning surface acts as an intermediate tool to modify the retaining ring surface properties, bridging the gap between rough machined surfaces and the smooth surfaces required for efficient polishing.
2Manufacturing precision
If extensive break-in procedures are performed on new retaining rings using dummy wafers, then surface flatness and roughness are improved, but capital and labor costs increase significantly
Solution Approach 1:
The conditioning fixture performs the surface preparation action beforehand, before the retaining ring is installed in the polishing system. This preliminary conditioning eliminates the need for time-consuming break-in procedures with dummy wafers, reducing both time and cost while achieving the same surface preparation goals.
Solution Approach 2:
The patent extracts the conditioning function from the production polishing process itself. By separating the conditioning operation into a standalone preliminary step using a dedicated fixture, the time-consuming break-in procedure is removed from the critical production path, allowing retaining rings to be quickly prepared without consuming polishing system time and resources.
3Productivity
If the sacrificial surface is made smoother through conventional methods, then polishing efficiency improves, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The patent changes the geometric parameters of the conditioning fixture, specifically using a tapered surface with a controlled angle (e.g., 5 degrees). This parameter change in the conditioning apparatus geometry enables it to produce the desired surface characteristics on the retaining ring through simple mechanical contact, achieving smooth surfaces without complex manufacturing processes.
Solution Approach 2:
The conditioning fixture applies localized quality changes to the retaining ring surface by using a tapered conditioning surface that contacts only the sacrificial surface area. This localized approach modifies only the necessary region to achieve optimal polishing efficiency without requiring complex apparatus that would affect the entire retaining ring structure.
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 solution achieves optimal polishing with reduced particle generation and enhanced surface roughness, thereby improving the efficiency and cost-effectiveness of the CMP system by simplifying the production and conditioning of retaining rings.
Implementation Method 1
The sacrificial surface is conditioned by rotating the retaining ring on a rotating polishing pad in a CMP system
Implementation Method 2
A clamp device is provided that applies a lateral load to an inside diameter or outside diameter sidewall of the retaining ring
Data Source
AI summary
A retaining ring for a polishing process is disclosed. The retaining ring includes a body comprising an upper portion and a lower portion, and a sacrificial surface disposed on the lower portion, the sacrificial surface comprising a negative tapered surface having a taper height that is about 0.0003 inches to about 0.00015 inches.