Substrate Rinse Timing to Prevent Back Surface Particle Contamination
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Solution Overview
Problem
Conventional polishing methods for semiconductor substrates fail to prevent particles on the back surface from contaminating the front surface due to improper timing and flow rate control of the rinse liquid, leading to reduced yield and device contamination.
Innovation Solution
A polishing method and apparatus that controls the timing and flow rate of the rinse liquid, starting with the front surface and delaying the rinse liquid to the back surface by a preset time or adjusting the flow rates to ensure the front surface liquid reaches the peripheral area before the back surface liquid, thereby preventing particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rinse liquid is fed simultaneously to both the front surface and back surface of the substrate, then both surfaces are cleaned efficiently, but particles on the back surface flow around to the front surface causing contamination
Solution Approach 1:
The rinse liquid is fed to the front surface of the substrate before being fed to the back surface. This preliminary action ensures that the front surface is already cleaned and ready to receive the substrate without particle contamination from the back surface rinse liquid, thereby resolving the contradiction between cleaning efficiency and contamination prevention
Solution Approach 2:
The feeding of rinse liquid to the front surface and back surface is performed in periodic sequence rather than simultaneously. The front surface is rinsed first, then after a predetermined time interval, the back surface is rinsed. This periodic action prevents particle contamination while maintaining cleaning efficiency
2Manufacturing precision
If the rinse liquid is fed to the back surface first or simultaneously, then the back surface is cleaned, but the cleaning time for the front surface is reduced due to time constraints
Solution Approach 1:
The rinse liquid feeding to the front surface and back surface is performed continuously in sequence without interruption. The front surface is rinsed first, then immediately followed by back surface rinsing, ensuring both surfaces receive adequate cleaning time while maintaining continuous productive action
Solution Approach 2:
The front surface rinsing is performed as a preliminary action before back surface rinsing. This ensures the front surface receives sufficient cleaning time and is prepared in advance, preventing time loss while maintaining high cleaning quality for both surfaces
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
Effectively prevents particles on the back surface from flowing to the front surface, reducing contamination and enhancing yield by ensuring the front surface is cleaned before the back surface liquid reaches it, thus maintaining the integrity of the device surface.
Implementation Method 1
The rinse liquid fed to the front surface and back surface of the substrate flows toward the peripheral portion of the substrate by a centrifugal force resulting from the rotation of the substrate
Data Source
AI summary
A polishing apparatus 100 includes a holding stage 4 that holds a central portion of a back surface of a substrate W, a motor M1 that rotates the holding stage 4, a front surface nozzle 36 that feeds a rinse liquid to a front surface of the substrate W, a back surface nozzle 37 that feeds the rinse liquid to a back surface of the substrate W, a rinse liquid control section 110 that feeds the rinse liquid through the back surface nozzle 37 after a preset time elapses since the start of feeding of the rinse liquid through the front surface nozzle 36 and a polishing head assembly 1A that polishes a peripheral portion of the substrate installed on the holding stage 4 after the rinse liquid control section 110 feeds the rinse liquid to the substrate W.