Laval Nozzle Supersonic Release for Wafer Polishing
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Solution Overview
Problem
The existing polishing methods for semiconductor wafers face challenges in preventing contamination of release nozzles and ensuring proper fluid delivery into small gaps between the wafer and the membrane, leading to potential damage to the wafer and contamination of subsequent wafers.
Innovation Solution
A polishing method utilizing a Laval nozzle to eject a supersonic parallel flow as a release jet, which prevents contaminants from adhering to the nozzle and allows for effective delivery into small gaps without inflating the membrane excessively, thus preventing wafer damage and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional release nozzle is used to eject fluid into the gap between the wafer and membrane, then the wafer can be released, but contaminants adhere to the nozzle causing damage to fine interconnects and contamination of subsequent wafers
Solution Approach 1:
The patent replaces the conventional subsonic fluid ejection system with a supersonic fluid ejection system using a Laval nozzle. The supersonic flow regime fundamentally changes the fluid dynamics, creating a jet that maintains coherence and prevents contaminant adhesion to the nozzle surface, thereby eliminating the contamination problem while effectively releasing the wafer
Solution Approach 2:
The patent changes the flow parameters from subsonic to supersonic by using a Laval nozzle geometry. This parameter change transforms the fluid behavior, creating a high-velocity jet that prevents contaminant accumulation on the nozzle and delivers cleaning fluid effectively into the small gap between the wafer and membrane without causing damage
2Manufacturing precision
If the membrane is inflated excessively to deliver fluid into the small gap, then fluid delivery improves, but the wafer and fine interconnects may be damaged
Solution Approach 1:
The patent replaces the mechanical inflation method with a supersonic jet injection method. The Laval nozzle generates a high-velocity fluid jet that penetrates the small gap between the wafer and membrane without requiring excessive membrane inflation, thus maintaining wafer integrity while achieving effective fluid delivery
Solution Approach 2:
The patent employs periodic or pulsed supersonic jet injection rather than continuous high-pressure inflation. This periodic action allows precise control of fluid delivery into the gap, achieving manufacturing precision while avoiding sustained high forces that could damage fine interconnects
3Ease of manufacture
If cleaning fluid is ejected onto the polishing head above the pusher, then the polishing head is cleaned, but the release nozzle becomes contaminated with abrasive grains and polishing debris
Solution Approach 1:
The patent replaces the conventional subsonic cleaning fluid ejection with supersonic ejection. The supersonic jet creates a coherent flow that prevents abrasive grains and polishing debris from adhering to the release nozzle surface, enabling effective cleaning of the polishing head without contaminating the release nozzle
Solution Approach 2:
The patent converts the potentially harmful effect of high-velocity flow (which could dislodge and spread contaminants) into a beneficial effect. The supersonic jet's coherence and pressure distribution prevent contaminant adhesion to the nozzle, transforming what could be a contamination risk into a self-cleaning mechanism for the release nozzle
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 effectively prevents nozzle contamination, ensures accurate release of the wafer without damaging fine interconnects, and increases throughput by maintaining a clean and efficient polishing process.
Implementation Method 1
ejecting a supersonic parallel flow as a release jet
Implementation Method 2
utilizing a Laval nozzle to eject a supersonic parallel flow
Data Source
AI summary
A polishing method which can prevent a contamination of a release nozzle for releasing a substrate, such as a wafer, from a polishing head, is disclosed. The polishing method includes: polishing a substrate by pressing the substrate against a polishing pad on a polishing table by a polishing head while moving the polishing table and the polishing head relative to each other; moving the polishing head, holding the substrate, to a predetermined position above a substrate transfer device; cleaning the substrate by ejecting a cleaning fluid onto the substrate held by the polishing head located at the predetermined position; during cleaning of the substrate, discharging a fluid from a release nozzle located at the substrate transfer device; and after cleaning of the substrate, releasing the substrate from the polishing head by ejecting a releasing shower from the release nozzle into a gap between the polishing head and the substrate.