Pulsed RF Bias for Molybdenum Oxide Reduction in BEOL
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Solution Overview
Problem
Existing methods for removing molybdenum oxide layers in semiconductor manufacturing, such as reactive-ion etching with continuous RF bias, degrade the dielectric constant of low-k substrates and are inefficient, leading to increased contact resistance and signal attenuation.
Innovation Solution
Applying an RF pulsed bias with a duty cycle to the substrate support, alternating between an ON period for ion excitation and an OFF period for by-product removal, enhances molybdenum oxide removal while preserving the dielectric constant of low-k substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous RF bias is applied during reactive-ion etching to remove molybdenum oxide, then the oxide removal process is continuous, but the dielectric constant of low-k substrates is degraded and the process is inefficient
Solution Approach 1:
The patent applies pulsed RF bias instead of continuous RF bias, creating periodic cycles of ion bombardment followed by relaxation periods. This allows oxide removal during the pulse phase while protecting the substrate dielectric during the off-phase, resolving the contradiction between removal efficiency and substrate integrity
Solution Approach 2:
The system dynamically adjusts the RF bias by switching between on and off states, controlling the ion flux to the substrate in real-time. This dynamic control enables efficient oxide removal while preventing excessive ion damage to the low-k substrate dielectric constant
2Reliability
If continuous RF bias voltage is applied throughout the treatment process, then the substrate surface is continuously bombarded, but this degrades the dielectric constant and is inefficient for removing molybdenum oxide layers
Solution Approach 1:
By implementing periodic pulsed RF bias cycles, the system achieves reliable oxide removal that reduces contact resistance, while the periodic nature prevents the harmful degradation of dielectric constant that would otherwise occur with continuous bombardment
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 pulsed RF bias method improves molybdenum oxide reduction efficiency, reduces contact resistance, and maintains the integrity of low-k substrates, enhancing the electrical performance of integrated circuits.
Implementation Method 1
an inductive coil disposed about the dielectric lid and configured to generate a plasma within the processing chamber
Implementation Method 2
A radio frequency (RF) power supply creates an electromagnetic field that ionizes the gas to create a plasma
Implementation Method 3
deliver an RF signal from an RF power source coupled to the inductive coil to form a plasma over the surface of the substrate support
Data Source
AI summary
Embodiments herein are generally directed to systems and methods for removing metal oxide layers for back-end-of-line processes. A substrate processing system includes a processing chamber configured to generate a plasma within the processing chamber, a substrate electrode embedded within a substrate support assembly disposed within the processing chamber, a radio frequency (RF) generator assembly coupled to the substrate electrode, and a controller. The controller is configured to flow a cleaning gas over a surface of a substrate support disposed within a processing chamber and generate a radio frequency (RF) pulsed bias that delivers an RF waveform for a first portion of a pulse period and halts the delivery of the RF waveform for a second portion of the pulse period and apply the RF pulsed bias to the substrate electrode while the plasma is present in the processing chamber.