Semiconductor Wafer Sonic Cleaning With Pulsed Bubble Cooling
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Solution Overview
Problem
Conventional ultra or mega sonic cleaning methods for semiconductor wafers face challenges in efficiently removing particles from fin structures, trenches, and vias without causing damage to patterned structures, as high power levels required for effective cleaning often lead to significant wafer damage.
Innovation Solution
A method involving a sonic transducer that alternates power settings to control bubble cavitation, allowing for efficient particle removal while maintaining sonic mechanical force below damage thresholds by cooling down bubbles between power cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power sonic energy is used to remove particles efficiently, then particle removal efficiency improves, but wafer damage increases
Solution Approach 1:
The patent applies periodic pulsed sonic energy instead of continuous high power sonic energy. The system delivers sonic energy in controlled pulses with specific duty cycles (e.g., 10-90% power levels alternating between active and inactive periods), allowing bubble cavitation to be sustained for particle removal while providing cooling intervals that prevent wafer damage from excessive thermal accumulation.
Solution Approach 2:
The patent dynamically adjusts sonic power levels and pulse durations based on real-time process conditions. The system modulates the sonic transducer output to maintain optimal cavitation intensity for particle removal while adapting power delivery to prevent damage, transitioning from static high power to dynamic controlled power delivery.
2Productivity
If continuous high power sonic energy is applied, then particle removal efficiency increases, but bubble temperature rises causing wafer damage
Solution Approach 1:
The patent employs periodic pulsed sonic energy delivery with controlled duty cycles that alternate between active cavitation phases and inactive cooling phases. This allows bubble cavitation to generate sufficient mechanical force for particle removal during active phases while the inactive phases allow thermal dissipation, preventing bubble temperature from rising to damage levels.
Solution Approach 2:
The patent incorporates cooling intervals before bubble temperature reaches damaging levels. By anticipating thermal accumulation during continuous sonic energy application, the system preemptively introduces pause periods that allow thermal diffusion and cooling, cushioning against the harmful effects of excessive bubble temperature before they occur.
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 approach effectively removes foreign particles from semiconductor wafers without causing damage, maintaining stable cavitation and ensuring efficient cleaning while preventing structural harm.
Implementation Method 1
Ultra sonic or mega sonic waves generate bubble cavitation to apply mechanical force to the wafer structures under cleaning
Implementation Method 2
imparting sonic energy to the cleaning liquid from a sonic transducer during the cleaning process
Implementation Method 3
the bubbles in the cleaning liquid can be sufficiently cooled down after the cleaning in each first period of time to avoid damages to the wafer
Data Source
AI summary
A method for controlling damages in cleaning a semiconductor wafer comprising features of patterned structures, the method comprising: delivering a cleaning liquid over a surface of a semiconductor wafer during a cleaning process; and imparting sonic energy to the cleaning liquid from a sonic transducer during the cleaning process, wherein power is alternately supplied to the sonic transducer at a first frequency and a first power level for a first predetermined period of time and at a second frequency and a second power level for a second predetermined period of time, the first predetermined period of time and the second predetermined period of time consecutively following one another, wherein at least one of the cleaning parameters is determined such that a percentage of damaged features as a result of the imparting sonic energy is lower than a predetermined threshold.