Oblique Sputtering Power Modulation for Film Uniformity
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Solution Overview
Problem
Conventional oblique incidence sputtering techniques result in nonuniform sheet resistance distribution when depositing magnetic films, especially with high power and multiple targets, leading to nonuniform film deposition and material distribution.
Innovation Solution
A sputtering apparatus and method that controls discharge power as a sine wave function relative to the rotational position of the substrate, adjusting power based on the positional relationship between the substrate and cathode to maintain uniform film thickness and composition, using a substrate-side magnet to form a directional magnetic field and a controller to calculate and apply varying power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If discharge power is increased to achieve higher sputtering rates, then productivity is improved, but film thickness uniformity deteriorates
Solution Approach 1:
The discharge power is applied periodically in synchronization with substrate rotation, using sinusoidal or triangular waveforms that vary power throughout the rotation cycle. High power is applied when the cathode is in favorable positions relative to substrate regions needing more material, and reduced when in positions that would cause over-deposition, thereby maintaining uniformity while achieving high average sputtering rates
Solution Approach 2:
The system transitions from static constant power application to dynamic power modulation that adapts to the changing geometric relationship between cathode and substrate during rotation. The power level is continuously adjusted based on real-time positional feedback, enabling high overall deposition rates while compensating for local variations in material flux
2Adaptability or versatility
If multiple targets are used for co-sputtering to achieve complex film compositions, then film composition versatility is improved, but composition uniformity deteriorates
Solution Approach 1:
Each target's discharge power is modulated periodically and independently according to its specific positional relationship with the substrate during rotation. This allows sophisticated temporal control of material flux from each target, enabling complex compositions to be deposited uniformly by compensating for geometric effects on a per-target basis
Solution Approach 2:
The power modulation scheme is tailored to each individual target's location and orientation relative to the substrate. Each target receives a customized power waveform that accounts for its specific geometric relationship with different substrate regions, ensuring that each material contributes uniformly to the final composite film
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
Achieves high uniformity in in-plane film distribution, reducing nonuniformity to less than 1%, enabling the manufacturing of high-performance electronic devices with consistent film properties.
Implementation Method 1
a cathode which supports a target is arranged offset diagonally above the substrate. While rotating the substrate along its processing surface, the target material is sputtered by oblique incidence sputtering
Implementation Method 2
applying a high voltage to a cathode to generate a discharge between the cathode and a substrate holder
Implementation Method 3
a substrate-side magnet to form a directional magnetic field
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A sputtering apparatus includes a substrate holder (22) which holds a substrate (21) to be rotatable in the plane direction of the processing surface of the substrate (21), a substrate-side magnet (30) which is arranged around the substrate (21) and forms a magnetic field on the processing surface of the substrate (21), a cathode (41) which is arranged diagonally above the substrate (21) and receives discharge power, a position detection unit (23) which detects the rotational position of the substrate (21), and a controller (5) which controls the discharge power in accordance with the rotational position detected by the position detection unit (23).