Composite Etch Stop Layer for Contact Field Plate
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Solution Overview
Problem
High voltage transistor devices face challenges in achieving high breakdown voltages while minimizing switching losses, as existing field plate configurations either burden the gate-to-drain capacitance or require additional processing steps increasing fabrication costs.
Innovation Solution
A high voltage transistor device with a field plate made from non-gate materials formed concurrent with the back-end-of-the-line metal layer, featuring a dielectric layer extending from the gate electrode to the drift region, and metal contacts extending through an inter-level dielectric layer to enhance electric field distribution and breakdown voltage without increasing fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a field plate is formed using existing configurations, then breakdown voltage can be enhanced, but gate-to-drain capacitance is burdened or additional processing steps are required
Solution Approach 1:
The field plate formation process is segmented into distinct stages: forming the first etch stop layer, depositing the field plate material, and selectively removing portions. This segmentation allows the field plate to be created without burdening the gate-to-drain capacitance by separating the field plate material deposition from the gate electrode structure.
Solution Approach 2:
A first etch stop layer is introduced as an intermediary element between the substrate and the field plate material. This intermediary layer facilitates the selective removal of field plate material while protecting underlying structures, enabling breakdown voltage enhancement without complicating the gate-to-drain capacitance structure.
2Strength
If existing field plate configurations are used, then breakdown voltage is improved, but additional processing steps increase fabrication costs
Solution Approach 1:
The field plate formation process is merged with existing fabrication工艺流程 by using the same etch stop layer and inter-level dielectric layer that are already present in the device structure. This merging eliminates the need for additional processing steps and reduces fabrication costs while still achieving enhanced breakdown voltage.
Solution Approach 2:
The first etch stop layer serves multiple functions: it acts as a protective layer during field plate material deposition, provides a selective etch barrier, and integrates with the existing inter-level dielectric structure. This multi-functionality reduces the need for additional processing steps and lowers fabrication costs.
3Reliability
If field plate material is deposited over the gate electrode, then electric field distribution is improved, but selective removal becomes difficult
Solution Approach 1:
The first etch stop layer is formed preliminarily before depositing the field plate material. This preliminary action creates a selective etch barrier that enables easy removal of the field plate material from specific regions while leaving it intact in other regions, solving the selective removal difficulty.
Solution Approach 2:
The field plate material is selectively removed from portions of the gate electrode based on local requirements. The first etch stop layer enables this local quality differentiation by providing a selective etch barrier, allowing the field plate to be present in regions where electric field distribution improvement is needed while being removed in other regions.
Data Source
AI summary
The present disclosure, in some embodiments, relates to a method of forming an integrated chip. The method may be performed by forming a gate structure over a substrate and between a source region and a drain region. A composite etch stop structure is formed over the gate structure and a first inter-level dielectric (ILD) layer is formed over the composite etch stop structure. The composite etch stop structure has a plurality of stacked dielectric materials. The first ILD layer is etched to concurrently define contact openings extending to the substrate and a field plate opening extending to the composite etch stop structure. The contact openings and the field plate opening are concurrently filled with one or more conductive materials.