Magnetron Erosion Profile for Sputtering Uniformity
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Solution Overview
Problem
Sputtering processes face challenges in achieving uniform thickness and sheet resistance across semiconductor wafers due to non-uniform deposition rates, leading to variations in the deposited layer's properties.
Innovation Solution
A sputtering apparatus with a magnetron structure featuring a predetermined erosion rate profile and magnetic polarity arrangement, which guides ions to erode the target at varying rates to maintain uniform sheet resistance and thickness across the wafer, utilizing a pattern of magnets with opposed polarities to control plasma density and deposition patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional magnetron structure is used, then the sputtering process can be performed, but non-uniform deposition rates occur leading to variations in layer thickness and sheet resistance
Solution Approach 1:
The magnetron structure implements local quality by creating different erosion rates at different radial positions on the target. The erosion rate profile is designed with a first peak rate near the central axis and a second peak rate at 0.7-0.75 of the target radius, with intermediate regions having lower erosion rates. This non-uniform erosion pattern compensates for the natural deposition non-uniformity, achieving uniform thickness and sheet resistance across the wafer surface.
2Manufacturing precision
If the magnetron erodes the target uniformly, then the process is simple, but the deposited layer shows non-uniform thickness and sheet resistance
Solution Approach 1:
The magnetron structure changes the erosion rate parameter across the target surface to achieve uniform deposition. By designing the magnetic field configuration to produce a specific erosion rate profile (with peak rates at particular radial positions), the system transforms the uniform erosion parameter into a controlled non-uniform erosion pattern that compensates for deposition non-uniformity, thereby achieving uniform sheet resistance and thickness.
3Productivity
If the sputtering process runs at high speed, then productivity increases, but deposition uniformity across the wafer deteriorates
Solution Approach 1:
The magnetron structure performs preliminary action by pre-configuring the erosion rate profile before deposition begins. The magnetic field is arranged to create the desired non-uniform erosion pattern at the target surface, which proactively compensates for the non-uniform deposition that would otherwise occur during high-speed sputtering. This allows high productivity to be maintained while ensuring 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
The solution ensures a uniform deposition of the target material across the wafer, maintaining consistent sheet resistance and thickness, thereby improving the uniformity and quality of the deposited layer.
Implementation Method 1
Sputtering is a commonly used manufacturing process to deposit layers of metals and related materials in the fabrication of semiconductor integrated circuits
Implementation Method 2
A sputtering apparatus includes a magnetron with permanent magnet of opposite magnetic polarity
Data Source
AI summary
Some embodiments of the present disclosure provide a sputtering apparatus including a magnetron structure configured to erode a target according to a predetermined erosion rate profile symmetric to a central axis of the magnetron structure. The predetermined erosion rate profile includes a first peak rate in proximity to the central axis; and a second peak rate located at about from 0.7 to 0.75 of a radius of the target from the central axis.