GaN HEMT Gate-Field Plate Layout for Higher Breakdown Voltage
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Solution Overview
Problem
Gallium nitride-based high electron mobility transistor (HEMT) devices experience premature breakdown due to electric field concentration and uneven electric field distribution, particularly at the drain-side of the gate electrode, leading to lower-than-theoretical breakdown voltage and complex manufacturing processes with misalignment issues when using conventional field plates.
Innovation Solution
A method involving the simultaneous formation of gate and field plate receiving grooves using the same photomask, allowing for accurate placement of a field plate insulated from the epitaxial layer, which simplifies manufacturing and improves alignment accuracy, thereby enhancing breakdown voltage and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional field plate is disposed in a groove of the GaN-based device, then the breakdown voltage is increased and electronic effect under strong electric field is decreased, but the manufacturing process becomes complicated and misalignment occurs between the field plate and gate electrode
Solution Approach 1:
The patent combines the formation of the gate electrode groove and field plate groove into a single etching step using a unified photomask pattern. The photomask simultaneously defines both grooves, eliminating the need for separate etching processes and alignment steps. This merging of formation steps simplifies the manufacturing process while ensuring precise spatial relationship between the gate electrode and field plate, thereby maintaining high breakdown voltage without the complexity and misalignment issues of conventional separate formation methods
Solution Approach 2:
The photomask serves multiple functions: it defines the gate electrode groove, defines the field plate groove, and establishes the precise spatial relationship between these structures. By making the photomask a multi-functional tool that simultaneously patterns both critical features, the invention eliminates the need for multiple specialized photomasks and alignment procedures, thereby reducing manufacturing complexity while maintaining the reliability benefits of the field plate structure
2Reliability
If a conventional field plate is disposed in a groove of the GaN-based device, then the breakdown voltage is increased and electronic effect under strong electric field is decreased, but misalignment occurs between the field plate and gate electrode
Solution Approach 1:
The patent merges the patterning of the gate electrode groove and field plate groove into a single photolithography and etching step. The unified photomask pattern simultaneously defines both grooves with precise relative positioning, eliminating cumulative alignment errors that would occur with sequential processing. This ensures high manufacturing precision and accurate alignment between the field plate and gate electrode while maintaining the breakdown voltage enhancement provided by the field plate structure
Solution Approach 2:
The photomask is designed in advance to include the precise spatial relationship between the gate electrode groove and field plate groove patterns. By pre-defining the relative positions of both features in a single pattern, the invention eliminates the need for subsequent alignment operations, thereby ensuring high manufacturing precision and accurate alignment without the misalignment problems associated with conventional multi-step processes
Data Source
AI summary
A method for manufacturing a gallium nitride-based device includes: forming an epitaxial layer on a substrate, forming a source electrode and a drain electrode spaced apart from each other on the epitaxial layer, and forming a first dielectric layer between the source electrode and the drain electrode on the epitaxial layer; forming a second dielectric layer on the first dielectric layer, the second dielectric layer covering the source electrode and the drain electrode; etching the first dielectric layer and the second dielectric layer, so as to simultaneously form a gate receiving groove and a field plate receiving groove that expose the epitaxial layer between the source electrode and the drain electrode; forming a gate electrode in the gate receiving groove; and forming a field plate in the field plate receiving groove, the field plate being insulated from the epitaxial layer. A gallium nitride-based device is also provided.