CMP Pad Surface Property Measurement via Laser Reflection
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Solution Overview
Problem
Current CMP apparatuses lack the ability to accurately measure polishing pad surface properties, which are crucial for controlling CMP performance, as motor torque measurements are influenced by various factors beyond pad surface properties.
Innovation Solution
Incorporating a polishing pad surface property measuring device that applies a laser beam to the pad, receives reflected light, and uses Fourier transforms and numerical analysis to determine surface properties, allowing for closed-loop control of dressing conditions to maintain optimal pad performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor torque measurement is used to indirectly measure pad surface properties, then measurement capability is provided, but measurement precision deteriorates because torque is affected by multiple factors including substrate condition, dresser condition, and installation conditions
Solution Approach 1:
The patent extracts the measurement function from the mechanical motor torque system and creates a separate optical measurement system. The laser beam measurement device independently measures pad surface properties without being influenced by mechanical factors such as substrate condition, dresser condition, and installation conditions, thereby achieving precise measurement while maintaining system simplicity
Solution Approach 2:
The patent introduces an optical intermediary (laser beam) as a mediator between the measurement system and the pad surface. This optical mediator enables indirect measurement of surface properties through light reflection characteristics, avoiding direct mechanical contact and the associated interference from multiple factors
2Manufacturing precision
If polishing pad surface properties are not measured, then device complexity remains low, but manufacturing precision deteriorates because CMP performance cannot be controlled
Solution Approach 1:
The patent implements a feedback mechanism where the laser beam measurement device continuously monitors pad surface properties, and this information is fed back to control the polishing process. This enables real-time adjustment of polishing parameters to maintain optimal CMP performance, achieving precise manufacturing control through a relatively simple optical feedback system
Solution Approach 2:
The patent replaces complex mechanical measurement systems with a simpler optical measurement system. Instead of using mechanical sensors or indirect torque measurements, the invention uses laser light reflection to measure pad surface properties, achieving precise CMP performance control through non-contact optical measurement
3Reliability
If polishing pad is used repeatedly without monitoring, then productivity is maintained, but reliability deteriorates as polishing rate decreases and nonuniform polishing occurs
Solution Approach 1:
The patent applies preliminary action by measuring pad surface properties before polishing performance deteriorates. The laser measurement system detects changes in pad surface characteristics early, allowing proactive adjustment of polishing parameters or pad replacement before nonuniform polishing occurs, ensuring consistent reliability while maintaining productivity
Solution Approach 2:
The patent uses feedback from continuous pad surface property measurement to monitor polishing performance consistency. The measurement data provides real-time feedback on pad condition, enabling timely intervention to maintain uniform polishing quality throughout the pad's service life, thereby ensuring reliability without sacrificing productivity
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
Enables direct measurement and control of polishing pad surface properties, preventing abnormal CMP states, optimizing pad performance throughout its lifespan, and reducing consumable costs by extending the life of pads and dressers.
Implementation Method 1
a polishing pad surface property measuring device configured to apply a laser beam to a surface of a polishing pad and to receive reflected light from the polishing pad
Implementation Method 2
a processor configured to perform a Fourier transform on a reflection intensity distribution obtained by the polishing pad surface property measuring device to obtain a spatial wavelength spectrum of the surface of the polishing pad
Data Source
AI summary
The present invention relates to a CMP apparatus having a polishing pad surface property measuring device for measuring surface properties such as surface topography or surface condition of a polishing pad used for polishing a substrate such as a semiconductor wafer. The CMP apparatus includes a polishing pad surface property measuring device (30) configured to apply a laser beam to a surface of a polishing pad (2) and to receive reflected light from the polishing pad to obtain reflection intensity in each reflection angle, a processor (40) configured to perform a Fourier transform on a reflection intensity distribution obtained by the measuring device to obtain a spatial wavelength spectrum of the surface of the polishing pad and to obtain surface properties of the polishing pad by numerical analysis, a dressing control unit (23) configured to determine dressing conditions of the polishing pad (2) by a closed loop control based on the surface properties of the polishing pad obtained by the processor, and a dressing apparatus (20) configured to dress the polishing pad based on the dressing conditions determined by the dressing control unit.