Face-Up Wafer Planarization Using Electrochemical Metal Removal
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) methods face challenges in uniformly polishing substrates, leading to non-uniform film thickness and dishing of metal materials, which can result in lithography issues and reduced die yield.
Innovation Solution
The introduction of electrochemical planarization apparatuses that position the substrate face-up, using a conductive end effector and electrolyte with applied electric current to selectively remove metallic materials while preventing non-metallic material removal, combined with chuck mechanisms to flatten the substrate and improve uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP methods are used to planarize substrates, then material removal is achieved, but non-uniform film thickness and dishing of metal materials occur
Solution Approach 1:
The patent replaces the conventional mechanical CMP process with an electrochemical planarization process. Instead of using mechanical abrasion with polishing pads and slurry, the invention uses electrochemical reactions where a conductive end effector applies controlled current to selectively remove metallic materials through electrochemical dissolution. This substitution eliminates the mechanical stress that causes non-uniform removal and dishing, achieving superior planarity and thickness uniformity across the substrate surface.
Solution Approach 2:
The invention changes the fundamental parameter of material removal from mechanical force-based to electrochemical current-based. By controlling electrical current density, voltage, and electrochemical reaction conditions, the process achieves uniform material removal rates across different materials (metallic vs. non-metallic). The electrochemical parameters can be precisely controlled to prevent dishing while maintaining high removal rates, resolving the contradiction between material removal efficiency and uniformity.
2Productivity
If mechanical force is applied during CMP operations, then material removal is achieved, but exposed portions of different materials are removed at different rates leading to uneven polishing
Solution Approach 1:
The patent replaces mechanical force application with electrochemical current application. The conductive end effector delivers controlled current through the electrolyte to the substrate surface, inducing electrochemical dissolution of metallic materials. This eliminates the differential mechanical removal rates that occur in CMP because different materials respond differently to mechanical abrasion. Electrochemical dissolution provides more uniform material removal across different material types while maintaining high productivity through controlled current density.
Solution Approach 2:
The invention introduces an electrolyte as an intermediary medium between the conductive end effector and the substrate. The electrolyte facilitates ion transport and enables the electrochemical reaction to proceed uniformly across the substrate surface. This intermediary allows for controlled and uniform material removal by mediating the electrochemical interaction, preventing the direct mechanical contact that causes non-uniform polishing rates for different materials.
3Shape
If CMP is used for planarization, then substrate flattening is achieved, but metal materials are removed faster than dielectric materials resulting in dishing
Solution Approach 1:
The patent replaces mechanical polishing with electrochemical planarization using a conductive end effector. The electrochemical process selectively removes metallic materials through controlled electrochemical dissolution while leaving dielectric materials unaffected. This selective removal mechanism prevents dishing of metal features because the electrochemical reaction can be precisely controlled to match the desired removal profile, achieving both substrate flatness and metal feature uniformity simultaneously.
Solution Approach 2:
The invention applies local quality by using a conductive end effector that can deliver electrochemical treatment selectively to different regions of the substrate. The end effector design and current distribution can be optimized to provide localized material removal where needed while preserving metal features in other areas. This localized control of the electrochemical process enables precise shaping and planarization without causing dishing, as each region receives the appropriate amount of treatment based on its specific requirements.
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 enables uniform film thickness and improved metal feature uniformity across the substrate, reducing dishing and increasing die yield by selectively removing metallic materials without mechanically stressing the substrate.
Implementation Method 1
substrate electrochemical planarization apparatuses
Implementation Method 2
using a conductive end effector and electrolyte with applied electric current to selectively remove metallic materials
Data Source
AI summary
Exemplary substrate electrochemical planarization apparatuses may include a chuck body defining a substrate support surface. The apparatuses may include a retaining wall extending from the chuck body. The apparatuses may include an electrolyte delivery port disposed radially inward of the retaining wall. The apparatuses may include a spindle that is positionable over the chuck body. The apparatuses may include an end effector coupled with a lower end of the spindle. The end effector may be conductive. The apparatuses may include an electric contact extending from the chuck body or retaining wall. The apparatuses may include a current source. The current source may be configured to provide an electric current to an electrolyte within an open interior defined by the retaining wall.