Ion Source Baffle Structure for Uniform Plasma Beam Etching
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Solution Overview
Problem
Existing ion etching technologies face challenges in achieving uniform plasma density distribution across the target substrate due to varying plasma density from the central to peripheral regions, leading to non-uniform etching rates.
Innovation Solution
An ion source baffle with baffles arranged symmetrically on its inner wall is introduced, which gradually increases plasma quantity from the peripheral to central region, compensating for the larger outer holes in the screen grid design, ensuring uniform plasma beam formation by adjusting the plasma distribution across the target substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the screen grid has outer small holes larger than inner small holes to compensate for plasma density decrease from central to peripheral region, then etching uniformity is improved, but the plasma density distribution becomes non-uniform leading to peripheral region etching being too rapid
Solution Approach 1:
The ion source baffle is introduced as an intermediary component between the plasma generation region and the screen grid. It actively regulates plasma distribution by blocking excess plasma in the central region and allowing more plasma to reach the peripheral region, thereby compensating for the natural plasma density decrease without relying solely on variable hole sizes in the screen grid
Solution Approach 2:
The baffle structure changes the plasma distribution parameters by creating a non-uniform blocking effect - with larger blocking area in the central region and smaller blocking area in the peripheral region. This parameter change in plasma distribution compensates for the natural density gradient and achieves more uniform plasma density across the target substrate
2Device complexity
If plasma density continuously decreases from central to peripheral region in the discharge chamber, then the ion source structure is simplified, but etching uniformity deteriorates due to rapid etching in peripheral region
Solution Approach 1:
The ion source baffle serves as a mediating structure that modifies the natural plasma distribution without changing the basic ion source architecture. It provides a simple yet effective means to regulate plasma flow and achieve uniform etching while maintaining relatively simple device structure
Solution Approach 2:
The baffle is designed with non-uniform characteristics - with different blocking areas for different regions (larger blocking in central region, smaller blocking in peripheral region). This local variation in baffle structure creates the desired local plasma density adjustment to achieve overall etching 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
The ion source baffle ensures uniform plasma beam distribution by adjusting plasma density, thereby enhancing etching uniformity and ensuring the quality of the machining process.
Implementation Method 1
after plasma is shielded by the ion source baffle, the quantity of the plasma gradually increases from a peripheral region of the discharge chamber to a central region of the discharge chamber
Implementation Method 2
the ionized gas of Ar and O2 enters into a quartz discharge chamber through a specially-designed gas pressure equalizing insulator, and is excited through a high frequency wave initiated by an RF coil, so that electrons and positive ions in the plasma gas are mixed to form a plasma
Implementation Method 3
the plasma is transmitted to a target substrate in the form of an ion beam through a Grid assembly to etch the surface of the target substrate (wafer)
Data Source
AI summary
An ion source baffle includes a baffle body, wherein the baffle body is of a hollow structure; baffles are symmetrically fixedly arranged on an inner wall of the baffle body; the baffles extend towards the center of the baffle body; and in the direction from the inner wall of the baffle body towards the center of the baffle body, a shielding area formed by the baffles is reduced. The ion etching machine includes a discharge chamber, a reaction chamber and an ion source baffle, wherein the ion source baffle is clamped on an inner wall of the discharge chamber; and plasma sequentially passes through the ion source baffle and an ion source grid assembly. In the ion etching machine, the ion source baffle is additionally provided, such that after plasma is shielded by the ion source baffle.