Plasma Sheath Engineering for Conformal 3D Feature Treatment
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Solution Overview
Problem
Conventional plasma processing apparatuses lack control over the angular spread of ions, making it difficult to uniformly treat the sidewalls of small, three-dimensional structures such as trench capacitors and FinFETs, as ions are primarily directed at 0° or up to 5° angles of incidence.
Innovation Solution
The plasma sheath shape is modified by using insulating modifiers, such as pairs of insulators, to control the boundary between the plasma and the plasma sheath, allowing ions to impact the workpiece at a range of incident angles, from +60° to -60°, enabling more uniform treatment of small three-dimensional features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ions are directed at 0° or up to 5° angles of incidence in conventional plasma processing, then the plasma processing apparatus is simple to operate, but it cannot uniformly treat the sidewalls of small three-dimensional structures
Solution Approach 1:
An insulating modifier is introduced as an intermediary element between the plasma and the workpiece. This insulating modifier has a specific shape designed to modify the plasma sheath boundary, thereby controlling the angular spread of ions without requiring direct modification of the plasma source or chamber geometry. The insulating modifier acts as a mediator that translates the simple plasma generation into controlled angular ion distribution.
Solution Approach 2:
The shape of the plasma sheath boundary is changed by the insulating modifier, which alters the electric field distribution and consequently the angular spread parameter of the ion beam. By modifying the geometric parameters of the insulating modifier (such as its height, width, and position), the angular spread of ions can be precisely controlled to achieve uniform sidewall treatment.
2Manufacturing precision
If the plasma sheath shape is modified using insulating modifiers to allow ions to impact at a range of incident angles, then uniform treatment of three-dimensional features is achieved, but the device complexity increases
Solution Approach 1:
The insulating modifier serves multiple functions simultaneously: it acts as an electrical insulator to maintain plasma sheath integrity, a geometric element to control ion angular spread, and a positioning element to define the plasma-workpiece boundary. This multi-functionality reduces the need for separate components and justifies the added complexity by consolidating multiple control functions into a single element.
3Adaptability or versatility
If ions are directed only at 0° angles, then the plasma processing apparatus is simple, but it cannot effectively treat small three-dimensional structures such as trench capacitors and FinFETs
Solution Approach 1:
The insulating modifier creates local variations in the plasma sheath boundary, resulting in different ion incident angles at different locations on the workpiece. The local geometry of the insulating modifier is tailored to produce the desired angular distribution specifically at the sidewall regions of three-dimensional structures, while maintaining appropriate ion flux at other areas.
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 allows for conformal deposition and etching of complex three-dimensional structures by varying the range of incident angles, improving the uniformity of ion distribution and enhancing the ability to treat small features effectively.
Implementation Method 1
The plasma is bounded by a region proximate the workpiece generally referred to as a plasma sheath. The plasma sheath is a region that has fewer electrons than the plasma.
Implementation Method 2
Ions from the plasma are attracted towards a workpiece. Ions that are accelerated towards the workpiece generally strike the workpiece at about a 0° angle of incidence relative to the plane
Data Source
AI summary
A plasma processing tool is used to deposit material on a workpiece. For example, a method for conformal deposition of material is disclosed. In this embodiment, the plasma sheath shape is modified to allow material to impact the workpiece at a range of incident angles. By varying this range of incident angles over time, a variety of different features can be deposited onto. In another embodiment, a plasma processing tool is used to etch a workpiece. In this embodiment, the plasma sheath shape is altered to allow ions to impact the workpiece at a range of incident angles. By varying this range of incident angles over time, a variety of differently shaped features can be created.