Electrochemical Polishing Pad Layout for Silicon Carbide Planarization
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Solution Overview
Problem
Existing electrochemical mechanical polishing/planarization equipment faces challenges such as surface scratches, particle contamination, metal contamination, and high costs due to complex circuit designs and material wear, particularly when processing conductive substrates like silicon carbide, which require high polishing pressures and strong oxidizing slurry.
Innovation Solution
A novel electrochemical mechanical polishing/planarization equipment design featuring a polishing pad with penetrating holes for electrolyte, a simplified circuit through the polishing head, and independent control of electrochemical and mechanical polishing processes, reducing the need for conductive contacts on the pad and enabling efficient oxidation of silicon carbide surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple mechanical polishing is used to grind the silicon carbide wafer surface on a polishing pad, then the equipment structure is simple, but a high polishing pressure is required, the removal rate is low, resulting in low equipment production efficiency and high consumable consumption
Solution Approach 1:
The patent merges electrochemical reactions with mechanical polishing into a unified electrochemical mechanical polishing process. The polishing pad serves dual functions: mechanical abrasion through abrasive particles and electrochemical oxidation through electrolyte delivery via penetrating holes. This combination allows the system to achieve high removal rates without requiring high mechanical pressure, thereby improving productivity while maintaining reasonable device complexity.
Solution Approach 2:
The patent changes the chemical and electrical parameters of the polishing environment by introducing an electrolyte solution through penetrating holes in the polishing pad. This electrolyte enables electrochemical reactions that modify the silicon carbide surface, reducing its hardness and increasing the removal rate. The parameter change from purely mechanical to electrochemical-mechanical transformation allows efficient material removal at lower pressures.
2Productivity
If a chemical mechanical polishing process is used to polish silicon carbide, then the polishing rate can be increased, but a strong oxidizing slurry is required, which posts a significant challenge on corrosion resistance of equipment hardware
Solution Approach 1:
The patent changes the chemical parameters of the polishing slurry by controlling the electrolyte composition, pH value, and conductivity. The electrolyte contains oxidizing agents that enable electrochemical oxidation of silicon carbide at milder conditions compared to conventional strong oxidizing slurries. This parameter optimization achieves high polishing rates while reducing the corrosiveness to equipment hardware, thereby improving reliability.
Solution Approach 2:
The polishing pad incorporates penetrating holes that form a porous structure for electrolyte delivery. This porous design allows controlled distribution of the electrolyte across the polishing surface, enabling efficient electrochemical reactions without requiring excessive amounts of strong oxidizing chemicals. The localized electrolyte delivery reduces overall chemical exposure to equipment, minimizing corrosion risks.
3Reliability
If conductive contacts are added on the polishing pad to establish a circuit for electrochemical mechanical polishing, then the electrochemical reaction can be achieved, but the device complexity increases and may cause surface scratches and contamination
Solution Approach 1:
The polishing pad is designed with multi-functionality: it provides mechanical abrasion through abrasive particles, delivers electrolyte through penetrating holes for electrochemical reactions, and serves as an electrical conductor through its conductive material composition. By making the polishing pad itself conductive rather than adding separate conductive contacts, the system achieves electrochemical reaction capability while simplifying the overall device structure and eliminating potential sources of surface scratches and contamination.
Solution Approach 2:
The patent merges the electrical conduction function into the polishing pad structure itself. The conductive polishing pad integrates the functions of mechanical polishing, electrolyte delivery, and electrical conduction into a single component. This merging eliminates the need for separate conductive contacts, reducing device complexity and avoiding the harmful effects of additional contact elements on the wafer surface.
4Manufacturing precision
If a conventional chemical mechanical polishing process is used, then the surface defectivity can be reduced compared to mechanical polishing, but the planarization performance and polishing efficiency are limited for conductive substrates
Solution Approach 1:
The patent merges electrochemical reactions with mechanical polishing to create an electrochemical mechanical polishing process that simultaneously achieves high polishing efficiency and excellent surface quality. The electrochemical oxidation softens the silicon carbide surface for easier removal, while the mechanical polishing component maintains surface smoothness. This combination overcomes the limitations of conventional chemical mechanical polishing for conductive substrates by enhancing both productivity and manufacturing precision.
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
Significantly improves substrate material removal rates, reduces costs, minimizes surface defects and contamination, and extends polishing pad lifetime by integrating electrochemical reactions with mechanical polishing, while maintaining equipment reliability and simplicity.
Implementation Method 1
A chemical liquid is delivered to the polishing pad, and an electrochemical reaction occurs on the polishing surface of the conductive wafer substrate in the hole area
Implementation Method 2
silicon carbide surface can be oxidized through electrochemical reactions. If a considerable current density can be achieved, surface oxidation of silicon carbide materials can be significantly accelerated
Implementation Method 3
the polishing head pushes on the back of a wafer substrate, and the front surface of the wafer substrate or a wafer front surface film is polished or planarized on a polishing pad
Implementation Method 4
a polishing pad attached to an upper surface of the polishing table, and a polishing head rotates and moves relative to the polishing table
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention discloses an electrochemical mechanical polishing/planarization equipment for processing a polishing surface (51) of a conductive wafer substrate (5), which includes a power supply (1); a polishing table (2) with conductivity; a polishing pad (3) including an insulating active layer (31) and having holes (311) where a conductive chemical liquid (4) is accommodated; a polishing head (6) having conductivity and being attached to the back of the polishing surface (51). The power supply (1), the polishing table (2), the chemical liquid (4), the conductive wafer substrate (5), and the polishing head (6) in sequence form a conductive loop, and an electrochemical reaction layer is formed on the polishing surface (51) of the conductive wafer substrate (5). The polishing head (6) drives the wafer substrate (5) to move relative to the polishing pad (3), and to implement a mechanical polishing or a chemical mechanical polishing of the electrochemical reaction layer.