Wafer Cleaning Return-Portion Rinsing for Backside Particle Control
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Solution Overview
Problem
Conventional semiconductor wafer cleaning apparatuses still generate particles on the back surface of wafers despite existing technologies, necessitating a solution to suppress this issue.
Innovation Solution
The semiconductor wafer cleaning apparatus incorporates a disk-shaped rotary table with a cylindrical return portion and a nozzle head featuring a return portion rinse nozzle to supply pure water towards the return portion, positioned radially outward from the rotary table's inner wall, and a gas supply nozzle positioned at least 90 degrees away from the return portion rinse nozzle, to effectively rinse and dry the wafer surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-wafer cleaning apparatus is used, then cross-contamination between wafers is avoided and cleaning solution usage is reduced, but particles are still generated on the back surface of wafers
Solution Approach 1:
The invention extracts and separately addresses the source of particle generation (the return portion where chemical solution accumulates) by providing a dedicated rinse function for it, distinct from the main wafer cleaning process. This separates the contamination prevention function from the particle generation source, allowing both issues to be addressed independently.
Solution Approach 2:
The invention introduces an intermediary rinse function (return portion rinse function) that mediates between the chemical solution supply and the back surface of the wafer. By rinsing the return portion with pure water, it prevents chemical solution residues from becoming particles that could contaminate the wafer back surface.
2Manufacturing precision
If chemical solution is supplied to clean the back surface of the wafer, then polishing powder is removed, but chemical solution splashes and adheres to the back surface causing etching marks and particles
Solution Approach 1:
The invention converts the harmful effect of chemical solution splashing into a beneficial rinsing action. The returned chemical solution, which would normally cause contamination, is instead used to rinse the return portion itself, preventing it from becoming a source of particles and etching marks on subsequent wafers.
Solution Approach 2:
The invention performs a preliminary rinsing action on the return portion before it can contaminate the wafer back surface. By rinsing the return portion with pure water during or after chemical solution supply, it prevents the formation of etching marks and particles in advance.
3Productivity
If the rotary table rotates at high speed during drying, then the wafer surface is dried efficiently, but scattered chemicals are carried by airflow and adhere to the back surface
Solution Approach 1:
The invention performs preliminary cleaning of the return portion by rinsing it with pure water before the high-speed rotation drying process. This removes chemical solution residues that would otherwise be picked up by the airflow during high-speed rotation and deposited on the wafer back surface.
Solution Approach 2:
The invention extracts and removes the source of chemical residues (the return portion) by providing a dedicated rinse function, separating it from the main drying process. This allows high-speed rotation for efficient drying without the harmful effect of chemical adhesion.
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 configuration significantly reduces particle generation on the back surface of semiconductor wafers, as demonstrated by a decrease in light point defects post-cleaning, enhancing the cleaning process's effectiveness.
Implementation Method 1
a return portion rinse nozzle is provided in the recess of the nozzle head to supply pure water toward the return portion to rinse the return portion
Implementation Method 2
chemical solution such as hydrofluoric acid (HF) is supplied from the lower chemical supply nozzle 15 and the upper chemical supply nozzle 17 to remove polishing powder, etc. from the front and back surfaces of the semiconductor wafer W
Implementation Method 3
a drive unit (not shown) rotates the rotary table 11 at a predetermined rotational speed to rotate the semiconductor wafer W
Implementation Method 4
the supply of pure water from the wafer back surface rinse nozzle 16 and the wafer front surface rinse nozzle 18 is stopped, the rotational speed of the semiconductor wafer W is increased, and a gas such as nitrogen (N2) is supplied from a gas supply nozzle (not shown) to dry the front and back surfaces of the semiconductor wafer W
Data Source
AI summary
A semiconductor wafer cleaning apparatus that can suppress the generation of particles on the back surface of the semiconductor wafer. A semiconductor wafer cleaning apparatus comprises a rotary table having an opening in the center; a wafer holder provided on the top surface of the rotary table; a return portion provided on the bottom surface of the rotary table; a nozzle head having a centrally located recess and a horizontal portion disposed on the radially outer side of the recess; a lower chemical supply nozzle; and a wafer back surface rinse nozzle, the return portion is disposed near the opening, and a return portion rinse nozzle is provided in the recess of the nozzle head to supply pure water toward the return portion to rinse the return portion.