Stress-Free Polishing Nozzle with Bubble Isolation
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Solution Overview
Problem
The existing stress-free polishing technology for semiconductor wafers faces issues with bubble generation in nozzles used as electrodes, leading to poor surface roughness and defects due to incomplete electrolyte contact and uneven electrolyte distribution, which damages low K dielectric layers and affects the quality of semiconductor devices.
Innovation Solution
A nozzle design featuring an insulated foundation, conductive body, and nozzle head with a tube that separates electrolyte into two streams, preventing bubbles from entering the main fluid path and allowing for controlled electrolyte distribution and recycling, thereby improving surface roughness and removal uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common nozzle is used as an electrode for stress-free polishing, then the polishing process can be performed without mechanical force, but bubbles are generated in the nozzle and ejected on the wafer causing poor surface roughness and defects
Solution Approach 1:
The nozzle is divided into distinct functional sections: a conductive body serving as the electrode, an insulated foundation, and a separate tube forming the fluid path. This segmentation isolates the bubble generation zone (at the conductive body) from the electrolyte ejection path (through the tube), preventing bubbles from contaminating the wafer surface while maintaining electrochemical polishing functionality.
Solution Approach 2:
The tube acts as an intermediary element between the electrolyte supply and the wafer surface. It provides a dedicated fluid transport channel that bypasses the bubble-prone conductive body region, allowing clean electrolyte delivery to the wafer while the auxiliary fluid path carries away bubbles generated at the electrode.
2Productivity
If a common nozzle is used, then the structure remains simple, but the electrolyte distribution range and shape on the wafer surface cannot be controlled well, affecting removal rate and uniformity
Solution Approach 1:
The nozzle design incorporates adjustable parameters including the tube's position, orientation, and ejection port configuration. These dynamic elements allow optimization of electrolyte distribution patterns to match different wafer processing requirements, improving removal rate and uniformity without requiring a completely different nozzle design for each application.
3Productivity
If the nozzle ejects bubbles with electrolyte, then the polishing process continues, but the bubbles block electrolyte contact with the wafer surface causing incomplete polishing and charge accumulation
Solution Approach 1:
The harmful bubbles are extracted from the main electrolyte delivery path through a separate auxiliary fluid path. This extraction occurs at the source (near the conductive body where bubbles form) and directs bubbles away from the wafer surface, ensuring that only bubble-free electrolyte contacts the wafer for complete and uniform polishing.
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 nozzle design enhances the polished surface quality by preventing bubble ejection and allowing for customizable electrolyte distribution, improving the removal rate and uniformity of metal layers on semiconductor wafers.
Implementation Method 1
The stress-free polishing technology is based on the electrochemical polishing mechanism to remove the unnecessary copper layers without mechanical force
Implementation Method 2
An auxiliary fluid path is formed between an inner circumferential surface of the receiving portion and an outer circumferential surface of the tube
Data Source
AI summary
A nozzle for charging and ejecting electrolyte in SFP process is disclosed. The nozzle includes an insulated foundation defining a through-hole, a conductive body as negative electrode connecting with a power source for charging the electrolyte and an insulated nozzle head. The conductive body has a fixing portion located on the insulated foundation. The fixing portion forms a receiving portion inserted into the through-hole and defining a receiving hole passing therethrough. The insulated nozzle head has a cover assembled with the insulated foundation above the conductive body and a tube extending through the cover and defining a main fluid path through where the charged electrolyte is ejected for polishing. The tube is inserted in the receiving hole and stretches out of the receiving hole of the conductive body forming an auxiliary fluid path between an inner circumferential surface of the receiving portion and an outer circumferential surface of the tube.