ECMP Voltage and Speed Control for Tungsten Planarization
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Solution Overview
Problem
Conventional planarization techniques for semiconductor fabrication, such as chemical mechanical polishing (CMP) and electrochemical mechanical polishing (ECMP), often result in incomplete planarization, varied results across a wafer, feature dishing, erosion, and high down force, especially when dealing with metallic materials like tungsten.
Innovation Solution
The implementation of an electrochemical mechanical polishing (ECMP) process that involves varying the voltage and rotational speed of the polishing pad and substrate during the polishing process, allowing for improved planarity and reduced dependence on feature density, with specific voltage and rpm settings optimizing the removal rate and surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemical mechanical polishing (CMP) or electrochemical mechanical polishing (ECMP) is used, then material removal is achieved, but incomplete planarization and varied results across the wafer occur
Solution Approach 1:
The patent applies dynamics by varying the polishing parameters (voltage, rotational speed) during the polishing process rather than maintaining constant values. The voltage is changed at different stages to optimize material removal and planarization, and the rotational speed is adjusted to ensure uniform polishing across the wafer surface, resolving the contradiction between achieving complete planarization and maintaining process consistency
Solution Approach 2:
The patent implements periodic action through multi-stage voltage application during ECMP. Different voltage levels are applied in sequence (e.g., initial voltage for material removal, followed by reduced voltage for planarization), creating a periodic pattern of high and low voltage phases that achieves both complete material removal and uniform planarization across the wafer
2Productivity
If higher down force is applied during polishing, then material removal rate increases, but feature dishing and erosion worsen
Solution Approach 1:
The patent uses dynamics by adjusting the voltage parameter during the polishing process to optimize the balance between removal rate and feature integrity. By varying voltage rather than relying solely on increased down force, the process achieves high productivity while preventing feature dishing and erosion through electrochemical control of the removal mechanism
Solution Approach 2:
The patent applies parameter changes by modifying the voltage and rotational speed parameters during polishing. These parameter adjustments allow optimization of the removal rate without increasing down force, thereby maintaining feature integrity while achieving high productivity through controlled electrochemical mechanical polishing
3Productivity
If conventional ECMP with constant voltage is used, then material is removed, but metal recess and varied planarity occur
Solution Approach 1:
The patent applies dynamics by implementing time-varying voltage and rotational speed during ECMP. The voltage is adjusted at different stages of the polishing process, and rotational speed is varied to maintain uniform material removal across the wafer surface, achieving both high productivity and excellent surface uniformity that constant voltage ECMP cannot achieve
Solution Approach 2:
The patent implements periodic action through multi-stage voltage application where different voltage levels are applied in sequence. This periodic variation in voltage allows for optimized material removal during high-voltage phases while maintaining surface uniformity during low-voltage phases, resolving the contradiction between productivity and surface uniformity
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 achieves more uniform and efficient planarization across the wafer with reduced metal recess and increased consistency, improving the overall planarity and removal rate compared to conventional methods, while minimizing the need for high down force and preventing island formation.
Implementation Method 1
electrochemical mechanical polishing (ECMP) process
Implementation Method 2
electrochemical mechanical polishing (ECMP) process
Implementation Method 3
varying the voltage and rotational speed of the polishing pad and substrate during the polishing process, allowing for improved planarity
Data Source
AI summary
A method of removing a material from a surface includes providing a substrate comprising a material having a surface, contacting the surface with a polishing medium, applying a voltage to the substrate to remove material from the surface, and changing the voltage during the removing material from the surface. An electro-chemical mechanical polishing method includes providing a substrate having a surface, applying a platen to the surface, applying a first voltage to the substrate, rotating the platen and surface relative to each other at a first rotational speed, increasing to a second voltage, and decreasing to a second rotational speed.