Plasma Film Formation Wall Surface Composition Control
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Solution Overview
Problem
Film formation methods using plasma vapor deposition often result in composition shifts due to reverse sputtering, particularly for elements with high vapor pressure, leading to films with compositions different from the target material, which is undesirable for achieving desired properties in materials like PZT and Zn-containing compounds.
Innovation Solution
A film formation method where the substrate is surrounded by a wall surface with adhering target constituents, and physical treatments such as heat or AC voltage are applied to release these components into the film formation atmosphere, minimizing composition shifts by promoting the release of susceptible elements and maintaining the target composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sputtering is used to form films, then film formation is achieved, but composition shifts occur due to reverse sputtering of elements with high vapor pressure
Solution Approach 1:
The wall surface is pre-coated with constituent elements of the target material before film formation begins. This preliminary action creates a reservoir of material that continuously replenishes elements lost to reverse sputtering, maintaining composition accuracy without requiring excessive initial target material.
Solution Approach 2:
The wall surface acts as an intermediary between the target and substrate. It temporarily stores constituent elements and releases them gradually during film formation, mediating the composition transfer and compensating for reverse sputtering losses of volatile elements.
2Manufacturing precision
If target composition is increased to compensate for reverse sputtering, then desired film composition can be achieved, but target material is wasted
Solution Approach 1:
Instead of discarding the volatile elements that are reverse-sputtered from the target, the invention recovers them by depositing them on the wall surface. These elements are then continuously released back into the film formation atmosphere, converting what would be waste into a useful source of material.
3Productivity
If wall surface is heated to release adhering components, then film formation speed is improved, but control of composition becomes more difficult
Solution Approach 1:
AC voltage is applied periodically to the wall surface to release adhering components in cycles. This periodic action maintains a continuous supply of constituent elements without requiring constant high-temperature heating, thereby improving film formation speed while maintaining composition control through rhythmic release patterns.
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 minimizes composition shifts between the target and formed film, stabilizing the desired composition and improving film formation speed, applicable to various composition systems prone to reverse sputtering, including piezoelectric films.
Implementation Method 1
reverse sputtering is a phenomenon in which, if there is a large difference in ease of sputtering (sputter rate) among the constituent elements, a constituent element which is more susceptible to sputtering than the other constituent elements among the constituent elements deposited on the substrate is preferentially sputtered out of the surface of the film
Implementation Method 2
heating to release the components adhering to the surface into the film formation atmosphere
Implementation Method 3
applying an AC voltage to release the components adhering to the surface into the film formation atmosphere
Data Source
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Figure 5
AI summary
When a film containing constituent elements of a target (T) is formed on a substrate (B) through a vapor deposition process using plasma with placing the substrate (B) and the target (T) to face to each other, the film is formed with surrounding the substrate (B) with a wall surface (10S, 41S) having the constituent elements of the target (T) adhering thereto, and applying a physical treatment to the wall surface (10S, 41S) to cause the components adhering to the wall surface (10S, 41S) to be released into the film formation atmosphere.