Plasma Processing Method for Semiconductor Wafer Cleaning
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Solution Overview
Problem
Semiconductor manufacturing processes using plasma often result in impurities adhering to wafer surfaces, which can reduce yield and quality due to the confinement of charged particles by high-energy plasma barriers.
Innovation Solution
A plasma processing method that involves confining and then diffusing the plasma generation region after the desired process is completed, either by expanding the plasma generation area, lowering internal pressure, or changing reaction gases, to minimize impurity adherence during wafer de-chucking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma is generated and confined over the wafer to perform deposition or etching processes, then the desired manufacturing process is completed, but impurities adhere to the wafer surface reducing yield and quality
Solution Approach 1:
A plasma diffusion step is performed before wafer de-chucking to preliminarily remove impurities. The method generates plasma, completes the desired process, then performs an additional plasma diffusion step to eliminate charged particles and impurities from the wafer surface before removing the wafer from the chuck, preventing contamination at the point of removal.
Solution Approach 2:
The patent converts the harmful effect of plasma-confined charged particles into a beneficial cleaning mechanism. By controlling plasma parameters and using plasma diffusion with adjusted power and gas flow, the same plasma mechanism that deposits or etches is turned around to remove adhered impurities, transforming a harmful byproduct into a useful cleaning function.
2Manufacturing precision
If plasma generation region is confined over the wafer, then process precision is maintained, but plasma diffusion is limited and impurities remain concentrated
Solution Approach 1:
The plasma generation region is made dynamic by adjusting confinement ring positions and plasma power levels. During the desired process, rings are positioned to confine plasma for precision. During the diffusion step, rings are repositioned and power is adjusted to expand the plasma region, enabling impurity diffusion while maintaining process control through systematic parameter changes.
Solution Approach 2:
The patent systematically changes plasma parameters to transition from confined to diffused state. Power levels are adjusted, gas flow rates are modified, and confinement ring positions are changed to control plasma expansion. These parameter changes enable the plasma to transition from a confined state during processing to a diffused state for impurity removal.
3Productivity
If wafer is de-chucked immediately after process completion, then cycle time is reduced, but impurities adhere to wafer surface during de-chucking
Solution Approach 1:
Plasma diffusion is performed as a preliminary action before de-chucking. The method completes the desired process, then performs plasma diffusion to remove impurities, and only after this cleaning step is the wafer de-chucked. This preliminary cleaning prevents impurity adherence during removal without significantly extending total cycle time.
Solution Approach 2:
The plasma is kept generated and the process continuous throughout. Instead of stopping plasma generation after the desired process, the system maintains plasma generation and transitions to a diffusion mode, keeping the useful plasma action continuous while changing its function from processing to cleaning, thereby minimizing idle time and maintaining productivity.
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 method effectively reduces the amount of impurities adhering to the wafer surface, improving yield and quality by diffusing charged particles and lowering the plasma energy barrier, allowing for cleaner wafer de-chucking.
Implementation Method 1
generating a plasma over the wafer to perform a desired process
Implementation Method 2
the wafer may be chucked on an electrostatic chuck using an electrostatic force
Data Source
AI summary
Plasma processing methods of a semiconductor manufacturing apparatus which can minimize the amount of impurities adhered to the surface of a wafer, when a desired process using plasma is performed. According to the plasma processing methods of the semiconductor manufacturing apparatus, after the desired process is completed, the plasma generated over the wafer is diffused, and then the wafer is de-chucked.