CMP Pad Polishing Frequency Analysis via Binary Matrix Overlay
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Solution Overview
Problem
The existing chemical-mechanical polishing (CMP) process faces challenges in accurately analyzing the polishing frequency and number of polishing times on polishing pads with different patterns and profiles, leading to errors in material removal rates and endpoint detection.
Innovation Solution
A method is developed to analyze polishing frequency and number of polishing times by establishing analytical models, converting design images into binary numerical matrices, and applying correction methods such as least pixel number, scale factor, cross-section check, and straight line-path effective polishing factor to account for different patterns and profiles, ensuring accurate material removal and endpoint detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing pads with different patterns and profiles are used to improve material removal uniformity, then polishing effectiveness is improved, but measurement precision of polishing frequency and number of polishing times deteriorates
Solution Approach 1:
The patent transforms the physical polishing pad pattern into a numerical matrix representation, allowing computational analysis of polishing frequency and number of polishing times. By changing from direct physical measurement to numerical parameter calculation, the system can handle complex patterns while maintaining measurement precision.
Solution Approach 2:
The patent replaces mechanical measurement methods with computational modeling. Instead of physically measuring polishing frequency on complex-patterned pads, the system uses numerical matrices and algorithms to calculate polishing parameters, eliminating measurement errors associated with complex physical patterns.
2Productivity
If theoretical formulas are used to calculate polishing frequency, then calculation speed is improved, but manufacturing precision of material removal rate deteriorates
Solution Approach 1:
The patent pre-establishes numerical matrices representing the polishing pad patterns before the actual polishing process. This preliminary numerical representation allows for accurate calculation of polishing frequency and number of polishing times during the process, combining computational speed with precision.
Solution Approach 2:
The patent divides the polishing pad pattern into discrete numerical matrix elements, allowing independent calculation of polishing parameters for each segment. This segmentation enables both fast computational processing and precise tracking of material removal at different locations.
3Manufacturing precision
If endpoint detection is performed to ensure accurate material removal, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent implements a feedback mechanism where the calculated number of polishing times is continuously compared with actual polishing cycles. This allows real-time detection of polishing endpoint based on computational models rather than time-consuming physical measurements, maintaining accuracy while reducing time loss.
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 method effectively evaluates the polishing frequency and number of polishing times, reducing errors and improving the precision of material removal rates, enabling early prediction of uneven areas on wafers and optimizing the CMP process.
Implementation Method 1
The method of chemical-mechanical polishing (CMP) process is one of global planarization techniques which utilizes the mechanical manner by grinding material
Implementation Method 2
the chemical manner by acid-base balance solution to partially remove surface portion of the wafer
Implementation Method 3
the functions of the polishing pads includes: (1) uniformly spreading the slurry on the polished surface of the wafer
Implementation Method 4
MRR is described by Preston's formula: MRR=Cp×P×V, where 'Cp' is Preston coefficient, 'P' is down force or pressure, and 'V' is the relative velocity of wafer to pad
Data Source
AI summary
A method for analyzing the effectiveness of polishing frequency and the number of polishing times on the polishing pads having different patterns and profiles while performing the chemical-mechanical polishing process on the wafers is described. This method is to convert the images of various patterns and topography of the chips and grinding pads into binary images, and then calculates the binary images by numerical matrix method, which only needs to calculate the modified model of the position changed and the frequency of grinding during the rotation and deformation of different patterns and topography during relative movement, and then uses overlay model of effective grinding frequency to predict the distribution of effective grinding frequency at a fixed period of grinding time under a set grinding path. Further proposes the overlay model of the grinding frequency of “Least Pixel Number (LPN)”, “Cross-section Check CSC”, “Straight Line-Path Effective polishing Factor (SLEF)” and “Scale Factor (SF),” so as to develop the procedures of analyzing the distribution condition of effective grinding frequency on the surface of the chips. It is referential to design better patterns and topography of grinding pads as well as setting the assembly parameters for CMP machines in the future.