Rotating PVD Wafer Support With Capacitive RF Coupling
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Solution Overview
Problem
Existing PVD systems face challenges in achieving uniform thin film thickness across a wafer surface without compromising deposition rates or chamber geometry, particularly in multi-layer deposition sequences, and struggle with effective RF coupling and temperature control.
Innovation Solution
A PVD apparatus with a rotatable substrate support and capacitive RF coupling between a stationary and rotating portion, allowing for improved thickness uniformity, RF bias control, and temperature management without altering the chamber's basic geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If target to wafer separation is increased to improve uniformity, then thickness uniformity is improved, but deposition rate is reduced
Solution Approach 1:
The substrate support is made rotatable rather than stationary, allowing the substrate to rotate during deposition. This dynamic motion distributes the deposited material more uniformly across the substrate surface without requiring increased target-to-wafer separation, thereby maintaining high deposition rates while achieving improved thickness uniformity
Solution Approach 2:
The invention introduces rotational motion as a new dimension of control. Instead of adjusting only the spatial dimension (target-to-wafer separation), the system utilizes temporal dimension (rotation during deposition) to achieve uniformity, decoupling the trade-off between uniformity and deposition rate
2Manufacturing precision
If an off-axis rotating wafer support is used to improve uniformity for thin films, then thickness uniformity is improved, but chamber size and hardware complexity increase
Solution Approach 1:
The invention employs an off-axis rotation where the substrate rotates around a point that is offset from the substrate center. This asymmetric rotation pattern creates overlapping deposition zones that achieve superior uniformity for thin films while maintaining a compact chamber design without complex hardware
Solution Approach 2:
The rotation mechanism is segmented into independent components: the substrate support rotates independently on bearing elements, allowing simple implementation without requiring complex integrated chamber designs
3Manufacturing precision
If a rotating wafer support is used to improve uniformity, then thickness uniformity is improved, but RF coupling reliability deteriorates
Solution Approach 1:
An RF coupling mechanism is introduced as an intermediary between the stationary RF source and the rotating substrate support. This intermediary maintains continuous electrical connection through the rotation, enabling reliable RF bias application to the substrate throughout the deposition process while preserving the uniformity benefits of rotation
Solution Approach 2:
The invention replaces direct mechanical electrical connections with capacitive or inductive RF coupling that can accommodate rotational motion. This substitution eliminates the need for sliding contacts or flexible cables, improving reliability while maintaining the ability to apply RF bias to the rotating substrate
4Manufacturing precision
If a rotating wafer support is used to improve uniformity, then thickness uniformity is improved, but temperature control reliability deteriorates
Solution Approach 1:
A thermal coupling mechanism serves as an intermediary between the stationary heating/cooling system and the rotating substrate support. This intermediary maintains reliable thermal contact throughout rotation, enabling effective temperature control of the substrate while preserving the uniformity advantages of rotational deposition
Solution Approach 2:
The substrate support structure is designed to simultaneously perform multiple functions: mechanical support, rotational motion, electrical RF coupling, and thermal management. This multi-functionality integrates temperature control capability into the rotating assembly, ensuring reliable thermal regulation during deposition
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 apparatus achieves uniform film thickness with reduced non-uniformity (%1σ) to less than 0.1%, maintains high deposition rates, and ensures reliable RF and thermal coupling, enhancing process efficiency and reliability.
Implementation Method 1
the upper and lower portions are spaced apart so that RF power supplied to the lower portion is capacitively coupled to the upper portion
Implementation Method 2
a target material is sputtered onto a substrate by applying a potential difference between the target cathode and an anode. Positively charged Ar+ ions are attracted to the target and 'sputter' material from the target
Data Source
AI summary
A Physical Vapour Deposition (PVD) apparatus having a PVD chamber, a target, a substrate support in the PVD chamber comprising an upper rotatable portion having an upper surface on which a substrate can be supported and a lower stationary portion, an RF source configured to supply an RF signal having an RF power to the lower stationary portion, and an arrangement for rotating the upper rotatable portion during a PVD process performed in the PVD chamber. The upper rotatable portion and the lower stationary portion are spaced apart so that the RF power supplied to the lower stationary portion is capacitively coupled to the upper rotatable portion.