PECVD Showerhead Plasma Field Segmentation
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Solution Overview
Problem
Plasma-enhanced chemical vapor deposition (PECVD) processes often result in non-uniform thin film thickness across semiconductor wafers, particularly as wafer sizes increase, due to variations in the RF plasma field, which can compromise the integrity and performance of integrated circuit devices.
Innovation Solution
A PECVD apparatus is designed to create multiple plasma fields in different zones within the process chamber, with a central inner plasma field and an outer peripheral field, using independently controllable power sources and gas distribution showerheads to ensure uniform film deposition across the wafer surface, particularly for larger 450 mm wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single plasma field is used for deposition, then the process is simple, but film thickness uniformity across the wafer deteriorates
Solution Approach 1:
The single plasma field is segmented into multiple independent plasma fields (central and peripheral zones) that can be independently controlled. This segmentation allows different regions of the wafer to receive optimized plasma exposure, improving film thickness uniformity across the entire wafer surface while maintaining manageable system complexity through modular zone control.
Solution Approach 2:
Different plasma field characteristics are applied to different zones of the wafer surface. The central zone receives one plasma field configuration while the peripheral zone receives another, allowing local optimization of deposition parameters for each region to achieve uniform film thickness across the entire wafer.
2Productivity
If wafer size is increased to improve productivity, then more IC devices can be built per wafer, but film thickness uniformity deteriorates
Solution Approach 1:
The plasma field is segmented into multiple independently controllable zones that can be optimized for larger wafer dimensions. This allows the deposition process to scale to larger wafer sizes (450mm and beyond) while maintaining uniform film thickness by independently adjusting plasma parameters in different radial zones of the wafer.
Solution Approach 2:
The plasma field control is extended from simple radial zoning to include vertical dimension control through multiple showerheads at different heights. This multi-dimensional plasma field configuration enables uniform deposition across larger wafer areas by compensating for edge effects and radial variations through coordinated control of multiple plasma sources.
3Productivity
If RF plasma field strength is increased to improve deposition rate, then productivity improves, but film thickness uniformity deteriorates due to preferential central region deposition
Solution Approach 1:
The plasma field is divided into multiple independently controllable zones with different power levels. This allows the central region to receive higher plasma power for faster deposition while peripheral regions receive optimized power levels to compensate for edge effects, maintaining uniform film thickness across the wafer while achieving high overall deposition rates.
Solution Approach 2:
The plasma field configuration is made dynamically adjustable through independent power control of multiple zones and showerheads. This dynamic control allows real-time optimization of deposition rates and uniformity by adjusting plasma parameters during the deposition process, enabling both high productivity and film thickness uniformity.
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 achieves significantly improved film thickness uniformity across the wafer surface, reducing die reject rates and maintaining the integrity and performance of IC devices by fine-tuning deposition rates in both central and peripheral regions.
Implementation Method 1
A reactant or process gas containing the desired film material chemical precursors is introduced into the chamber and energized by a power source that generates an RF (radio frequency) (AC) or DC signal sufficient to excite a capacitive discharge and form an ionized gas plasma above the wafer
Implementation Method 2
Plasma-enhanced chemical vapor deposition (PECVD) is a chemical-based process used to deposit thin semiconductor material films or layers on a substrate such as a wafer
Data Source
AI summary
An apparatus and method are disclosed for forming thin films on a semiconductor substrate. The apparatus in one embodiment includes a process chamber configured for supporting the substrate, a gas excitation power source, and first and second gas distribution showerheads fluidly coupled to a reactive process gas supply containing film precursors. The showerheads dispense the gas into two different zones above the substrate, which is excited to generate an inner plasma field and an outer plasma field over the wafer. The apparatus deposits a material on the substrate in a manner that promotes the formation of a film having a substantially uniform thickness across the substrate. In one embodiment, the substrate is a wafer. Various embodiments include first and second independently controllable power sources connected to the first and second showerheads to vary the power level and plasma intensity in each zone.