GaN HEMT Field Plate Structure for Residue-Free Oxide Sealing
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Solution Overview
Problem
GaN HEMTs face issues such as residues forming at unwanted areas due to imprecise mask placement during field plate formation, leading to electrical performance loss and unwanted effects.
Innovation Solution
A semiconductor device structure with a thicker sealing oxide layer and separate field plate creation process, avoiding etching of the nitride layer for field plate formation, and a three-step gate contact etch process to improve precision and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used to create the SiN opening for field plate formation, then the field plate can be formed, but the mask may not be precisely located causing residues to remain in unwanted areas
Solution Approach 1:
The patent divides the field plate formation process into two separate steps: first forming the SiN opening, then forming the field plate structure. This segmentation allows each step to be optimized independently, reducing the risk of residues from mask placement errors affecting the entire structure.
Solution Approach 2:
The SiN opening is formed in advance before the field plate structure is created. This preliminary action allows the opening to be established with proper positioning, and subsequent field plate formation can proceed without risking residue contamination in unwanted areas.
2Ease of manufacture
If the SiN sealing layer is etched around the gate to create an opening for field plate formation, then the field plate can be formed, but too much SiN and SiO may be removed forming holes
Solution Approach 1:
The patent introduces an intermediary layer or process step between the SiN etching and field plate formation that provides better control over the etching depth and prevents over-etching. This intermediary mechanism ensures that the SiN opening is created with precise boundaries without forming holes.
3Reliability
If a thicker sealing oxide layer is used, then control over the electric field is improved, but the device structure becomes more complex
Solution Approach 1:
The patent optimizes the thickness parameter of the sealing oxide layer to achieve the desired electric field control. By carefully selecting and controlling the oxide layer thickness within specific ranges, the patent improves reliability without unnecessarily increasing device complexity.
Data Source
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AI summary
The semiconductor device (100) comprises a substrate (102) made of a semiconductor material, a gate structure (104) placed on the substrate, a passivation layer (106) placed on the substrate and on a portion of the gate structure, a sealing oxide layer (108) placed on the passivation layer, a first field plate (112) placed on a portion of the sealing oxide layer, a dielectric layer (114) placed on the first field plate and on the sealing oxide layer, a second field plate (132) placed on a portion of the layer, and a source contact metallization (124) and a drain contact metallization (126). The sealing oxide layer is thicker than the passivation layer.