GaN HEMT Guard Ring Layout for Surge Resistance in Compact Chips
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Solution Overview
Problem
High-electron-mobility transistors (HEMTs) using group III-V semiconductors like gallium nitride (GaN) face limitations in surge resistance due to the small gate capacity, which can lead to increased on-resistance and decreased breakdown voltage when exposed to static electricity, especially in compact transistor designs where the guard ring formation region is insufficient.
Innovation Solution
The semiconductor device incorporates a guard ring structure with a shield portion and a first shield electrode connected to the source electrode, forming a depletion region around the active region to disconnect the two-dimensional electron gas (2DEG) from the outside, enhancing surge resistance while maintaining the 2DEG at a source potential, and utilizing a pad-over-active (POA) structure to reduce chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guard ring formation region is arranged around an element region to increase resistance to static electricity, then surge resistance is improved, but chip area increases
Solution Approach 1:
The patent transitions from a planar guard ring structure to a three-dimensional structure by forming a recess in the semiconductor substrate and filling it with a conductive material. This vertical dimensionality change allows the guard ring to provide enhanced surge protection without proportionally increasing the chip area, as the protective structure extends downward into the substrate rather than only outward on the surface.
Solution Approach 2:
The guard ring structure is nested within the semiconductor substrate by forming a recess and filling it with conductive material. This nesting approach integrates the protective guard ring into the existing device structure, utilizing the substrate volume efficiently and minimizing the additional area required while maintaining effective electrostatic shielding.
2Area of stationary object
If the guard ring formation region is reduced to downsize the transistor, then chip area is reduced, but surge resistance becomes insufficient
Solution Approach 1:
By forming the guard ring in a recess that extends vertically into the substrate, the patent achieves effective electrostatic shielding in a compact footprint. The vertical extent of the recess provides enhanced protection without requiring a larger lateral area, thus maintaining surge resistance while enabling transistor downsizing.
Solution Approach 2:
The patent changes the geometric parameters of the guard ring structure by forming it in a recess with specific depth and cross-sectional dimensions. By optimizing these parameters, the guard ring achieves effective surge protection with a minimized area, allowing for compact transistor design without sacrificing reliability.
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 solution effectively improves surge resistance and reduces the chip area by creating an annular disconnection region of the 2DEG under the guard ring, preventing surge entry into the active region and maintaining the 2DEG at a source potential, thus enhancing the reliability and operation of the HEMT.
Implementation Method 1
a second semiconductor layer (18) arranged on the first semiconductor layer (16) to generate a two-dimensional electronic gas (2DEG) in the first semiconductor layer (16) in a vicinity of an interface between the second semiconductor layer (18) and the first semiconductor layer (16)
Implementation Method 2
the guard ring (30) is arranged in a peripheral part (R11) of the element region (R1) and includes a fourth semiconductor layer (32) arranged on the second semiconductor layer (18) and including an acceptor impurity, and a first electrode (34) arranged on the fourth semiconductor layer (32) and electrically connected to the source electrode (22) or the 2DEG (20)
Data Source
AI summary
A semiconductor device includes a first semiconductor and a second semiconductor layer arranged thereon to generate a 2DEG in the first semiconductor layer. A source electrode and a drain electrode are arranged on the second semiconductor layer. A third semiconductor layer including an acceptor impurity is arranged on the second semiconductor layer between the source electrode and the drain electrode. A gate electrode is arranged on the third semiconductor layer. The second semiconductor layer defines a boundary between an element region including an FET and an element separation region. A guard ring is arranged on the second semiconductor layer in a peripheral part of the element region. The guard ring includes a fourth semiconductor layer arranged on the second semiconductor layer and including an acceptor impurity and a first electrode arranged on the fourth semiconductor layer and electrically connected to the source electrode or the 2GEG.