RF Device Substrate Removal for Low Loss and Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-performance RF-devices face limitations due to linearity and low loss issues caused by interactions with the substrate, primarily attributed to electrical charges within the substrate material.
Innovation Solution
A method involving the formation of a BEOL-layer stack on a semiconductor substrate, attachment of a carrier structure, removal of the semiconductor substrate's lateral portion to expose the BEOL-layer stack's second main surface, and creation of a contacting region using metallization layers and metal contacts, including wolfram, to reduce substrate interactions and enhance electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the semiconductor substrate is retained to support the RF-device, then mechanical strength and structural stability are maintained, but substrate charges cause capacitive and inductive interactions that degrade linearity and increase loss
Solution Approach 1:
The patent removes the semiconductor substrate laterally around the device region, extracting the harmful substrate material that causes charge-induced interactions. The substrate is completely removed from the device region while the BEOL-layer stack remains supported by the carrier structure, eliminating the source of capacitive and inductive interactions without compromising device support.
Solution Approach 2:
The patent introduces a carrier structure as an intermediary to support the BEOL-layer stack after substrate removal. This carrier structure (which may be a temporary carrier or permanent support) mediates the mechanical support function, replacing the substrate's structural role while allowing complete lateral removal of the semiconductor material that causes harmful interactions.
2Reliability
If the lateral portion of the semiconductor substrate is removed to eliminate substrate charges, then linearity and loss performance are improved, but additional manufacturing steps and process complexity are required
Solution Approach 1:
The patent performs preliminary actions by attaching the carrier structure to the BEOL-layer stack before removing the substrate. This sequence ensures that the device structure is stabilized and supported before the substrate is laterally removed, preventing structural issues during and after substrate removal while achieving the desired linearity performance.
Solution Approach 2:
The patent segments the substrate removal process into specific lateral portions surrounding the device region. The removal is performed selectively around the device region rather than completely, allowing the device area to remain supported while eliminating harmful substrate material in the lateral portions, thus achieving linearity improvement with controlled process complexity.
3Reliability
If the contacting region of the BEOL-layer stack is opened to expose metal contacts, then electrical connectivity and device performance are enhanced, but the manufacturing process requires additional etching steps
Solution Approach 1:
The patent applies local quality by opening the contacting region specifically at locations where electrical connectivity is required. The etching process is localized to contact regions rather than being applied uniformly across the entire BEOL-layer stack, exposing metal contacts only where needed for electrical connection while leaving other areas intact, thus achieving enhanced connectivity with minimal additional manufacturing complexity.
Data Source
AI summary
A method for manufacturing a device includes: providing a semiconductor substrate having an RF-device; providing a BEOL-layer stack on the first main surface of the semiconductor substrate; attaching a carrier structure to a first main surface of the BEOL-layer stack; removing a lateral portion of the semiconductor substrate which laterally adjoins the device region to expose a lateral portion of the second main surface of the BEOL-layer stack; and opening a contacting region of the BEOL-layer stack at the lateral portion of second main surface of the BEOL-layer stack.