Polishing Pad Thickness Gauge Feedforward Control
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) methods, such as those using closed-loop control (CLC) with ITM or R-ECM, are costly and inefficient for second-step polishing after copper film removal, requiring thickness measurements and leading to decreased throughput and unstable polishing performance.
Innovation Solution
A feedforward control method that adjusts polishing time based on the wear or thickness of the polishing pad, using pre-calculated algorithms to maintain stable polishing performance without measuring the film thickness, applicable to both metal and oxide films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If closed-loop control (CLC) with ITM or R-ECM is used to maintain stable polishing performance, then polishing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a simple, inexpensive thickness gauge to measure polishing pad thickness instead of complex ITM or R-ECM systems. The polishing pad is treated as a consumable item whose thickness is periodically measured and used to adjust polishing time, replacing the need for expensive real-time control systems.
Solution Approach 2:
The patent replaces complex electronic control systems (ITM/R-ECM) with a simple mechanical measurement approach using a thickness gauge. The mechanical measurement of pad thickness combined with predetermined time correction values substitutes for the complex closed-loop control electronics.
2Manufacturing precision
If closed-loop control (CLC) with thickness measurement is used to maintain stable polishing performance, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent performs thickness measurement of the polishing pad in advance, before the actual polishing process. Correction values for polishing time are predetermined based on these advance measurements, allowing the main polishing process to proceed without interruptions for real-time measurements.
Solution Approach 2:
The patent extracts the thickness measurement step from the continuous polishing process and performs it separately in advance. This separation allows the polishing process to run continuously at full speed while thickness measurements are performed independently at convenient intervals.
3Manufacturing precision
If polishing time is adjusted according to polishing pad wear to maintain stable polishing performance, then manufacturing precision is improved, but operation complexity increases
Solution Approach 1:
The patent creates a lookup table of correction values in advance, based on predetermined relationships between polishing pad thickness and required polishing time adjustments. During operation, the operator simply needs to measure the current pad thickness and select the corresponding correction value from the table, rather than performing complex calculations.
Solution Approach 2:
The patent creates a simplified copy of the complex relationship between pad wear and polishing time in the form of a correction value table. This table copy allows operators to quickly determine the correct polishing time adjustment without understanding or calculating the underlying complex relationships.
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 allows for stable polishing performance throughout the life of the polishing pad at a lower cost than CLC methods, without decreasing throughput, and can handle second-step polishing effectively without thickness measurements.
Implementation Method 1
a substrate such as a semiconductor wafer is brought into sliding contact with the polishing surface, so that a film formed on the substrate is polished
Implementation Method 2
chemical mechanical polishing (CMP)... while a polishing liquid containing abrasive particles such as silica (SiO2) therein is supplied onto a polishing surface
Data Source
AI summary
A polishing method is used for polishing a film formed on a substrate by pressing the substrate against a polishing pad. The polishing method includes preparing, in advance, an algorithm for correction of polishing time from a relationship between a known amount of wear of the polishing pad or a known thickness of the polishing pad, and a polishing time and a polishing amount; setting a polishing target value for the film; and measuring an amount of wear of the polishing pad or a thickness of the polishing pad. The polishing method further includes determining an optimal polishing time for the polishing target value from the measured amount of wear of the polishing pad or the measured thickness of the polishing pad and from the algorithm; and polishing the film for the determined optimal polishing time.