CMP Process Control Matrix for Target Removal Profiles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Generating a process model in matrix formulation that accurately predicts material removal profiles during chemical mechanical polishing (CMP) is challenging due to variations in initial substrate thickness, polishing pad condition, retaining ring condition, relative speed, and applied pressure, leading to inconsistencies in achieving a target material removal profile.
Innovation Solution
A method involving the use of a matrix model that relates process parameters to calculated removal profiles, incorporating control and state parameters, and an in-situ monitoring system to adjust process parameters dynamically, thereby improving control parameter convergence and reducing within-wafer and wafer-to-wafer non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP process control methods are used, then the process is simple to operate, but the manufacturing precision of material removal profile is poor due to variations in process parameters
Solution Approach 1:
The patent transforms the CMP process control from using raw process parameters (pressure, speed, slurry flow) to using derived process control parameters (PCPs) that are calculated from measured material removal rates. This parameter transformation enables precise control of the material removal profile by directly relating control parameters to actual process outcomes, resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent replaces conventional mechanical/process-based control methods with a computational model-based control system. By using a material removal rate model that incorporates wafer-specific characteristics and real-time measurements, the system substitutes traditional trial-and-error or fixed-parameter control with predictive computational control, achieving higher precision while managing complexity through software-based solutions.
2Manufacturing precision
If process parameters are adjusted to achieve target removal profile, then manufacturing precision improves, but the time required for process optimization increases
Solution Approach 1:
The patent performs preliminary characterization of each wafer's material properties, initial thickness profile, and removal rate characteristics before the actual CMP process. This pre-measurement and pre-modeling phase allows the system to predict the optimal process control parameters in advance, eliminating time-consuming trial-and-error adjustments during production and enabling direct achievement of target removal profiles.
Solution Approach 2:
The patent implements a feedback mechanism where material removal rates are measured during or after the CMP process, and these measurements are fed back into the control model. The model then adjusts the process control parameters for subsequent wafers or process stages based on actual performance data, enabling continuous optimization and rapid convergence to target profiles without extensive manual tuning time.
3Reliability
If conventional polishing control is used, then the equipment operation is straightforward, but the consistency of material removal across wafers deteriorates due to pad condition variations
Solution Approach 1:
The patent implements real-time or post-process measurement of material removal rates and feeds this data back into the control model. By continuously monitoring actual removal performance and adjusting process control parameters accordingly, the system compensates for variations in polishing pad condition, retaining ring wear, and other equipment state changes, maintaining consistent wafer-to-wafer results despite equipment degradation over time.
Solution Approach 2:
The patent transitions from static, fixed process parameters to dynamic, adaptive process control parameters that change based on real-time measurements and equipment state. The system continuously updates the optimal PCPs for each wafer based on current pad condition, pressure distribution, and removal rate measurements, enabling the control system to adapt to equipment aging and maintain reliability without requiring frequent manual intervention or equipment replacement.
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 method enhances the precision of achieving target material removal profiles by minimizing non-uniformity and optimizing the CMP process, ensuring product wafers meet desired specifications with reduced rejection rates.
Implementation Method 1
The exposed surface of the substrate is typically placed against a rotating polishing pad with a durable roughened surface
Implementation Method 2
Chemical mechanical polishing (CMP) is one accepted method of planarization
Data Source
AI summary
A method of processing substrates includes: subjecting each respective first substrate of a first plurality of substrates to a process that modifies a thickness of an outer layer of the respective first substrate; generating a plurality of groups of process parameter values, wherein the plurality of process parameters comprise a plurality of control parameters and a plurality of state parameters; generating a plurality of measured removal profiles; generating a matrix that relates the plurality of process parameters to a calculated removal profile; for each respective second substrate of a second plurality of substrates, determining a target removal profile and a plurality of state parameter values; calculating respective control parameter values to apply to the respective second substrate by applying the target removal profile and the state parameter values to the matrix; and subjecting each respective second substrate to the process using the respective process parameter values.