Wafer Particle Removal via Multi-Cycle Spin Rinse
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Solution Overview
Problem
Current methods for removing particles from semiconductor wafers during the self-aligned silicide process are ineffective, leading to residual particles and non-uniformity, particularly in the 65 nm process and below, due to limitations in the wet station batch spin method.
Innovation Solution
A multi-cycle intermediate rinse process involving high-speed and low-speed wafer-rotation procedures, with specific rotational speed ranges and durations, alternating rotational directions, and the use of deionized water and ultrasonic vibration to enhance particle removal, followed by a final rinse process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batch spin method is employed in wet station to remove unreacted nickel and platinum, then 25 to 50 wafers can be treated collectively, but particle removal capability is limited and non-uniformity problems occur
Solution Approach 1:
The batch spin method is segmented into multiple sequential spin cycles (first spin cycle, second spin cycle, third spin cycle) with different rotational speeds and durations. Each cycle targets different particle sizes and locations, with the first cycle at high speed for large particles, the second at medium speed for medium particles, and the third at low speed for fine particles, thereby achieving uniform particle removal across all wafers while maintaining batch processing capacity
Solution Approach 2:
The rotational speed dynamics are optimized across multiple cycles: the first spin cycle uses high speed (300-500 rpm) for initial particle removal, the second cycle uses medium speed (200-300 rpm) for intermediate particles, and the third cycle uses low speed (100-200 rpm) for fine particles. This dynamic adjustment of rotational parameters enables effective particle removal across different scales while maintaining batch processing efficiency
2Productivity
If high rotational speed is used to remove particles, then particle removal efficiency increases, but non-uniformity and residual particles increase
Solution Approach 1:
The particle removal process employs periodic action through multiple sequential spin cycles with alternating speed patterns. The first cycle uses high speed for efficient particle removal, followed by a second cycle at medium speed to address remaining particles, and a third cycle at low speed to eliminate fine particles and prevent non-uniformity. This periodic variation in rotational speed maintains high overall removal efficiency while ensuring uniform wafer surface quality
Solution Approach 2:
The rotational speed parameter is systematically changed across different spin cycles: high speed (300-500 rpm) in the first cycle for efficient particle removal, medium speed (200-300 rpm) in the second cycle for intermediate particles, and low speed (100-200 rpm) in the third cycle for fine particles. This parameter optimization ensures both high removal efficiency and uniform wafer surface quality without residual particles
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 removes residual particles from the wafer surface, improving process yield and uniformity by combining mechanical and chemical forces with controlled rotational speeds and solvent temperatures.
Implementation Method 1
rotating the wafer at a high speed (a high-speed wafer-rotation procedure) first, and then conducting a procedure of rotating the wafer at a low speed
Implementation Method 2
a flushing solvent delivered to at least one cycle of the multi-cycle intermediate rinse process includes deionzied water
Implementation Method 3
ultrasonic vibration is concurrently performed during each cycle of the intermediate rinse process
Data Source
AI summary
A method of removing particles from a wafer is provided. The method is adopted after a process for removing unreactive metal of a salicide process or after a salicide process and having oxide residue remaining on a wafer or after a chemical vapor deposition (CVD) process that resulted with particles on a wafer. The method includes performing at least two cycles (stages) of intermediate rinse process. Each cycle of the intermediate rinse process includes conducting a procedure of rotating the wafer at a high speed first, and then conducting a procedure of rotating the wafer at a low speed.