Enhancement mode HEMT (high electron mobility transistor) device

Abstract

The invention belongs to the technical fields of semiconductors, and particularly relates to an enhancement mode HEMT (high electron mobility transistor) device. According to the enhancement mode HEMT device, a reverse polarization layer is grown on the upper surface of a barrier layer between a grid electrode and a drain electrode; the reverse polarization layer and the barrier layer produce reverse polarization to form two-dimensional hole gas (2DHG) in heterojunction interface; the reverse polarization layer, barrier layer, buffering layer form polarization super junctions; meanwhile, a metal grid electrode is not positioned between a source electrode and the drain electrode any more, instead, an insulation gate electrode is formed by etching a groove in the edge of the source edge far from the drain electrode; on one hand, longitudinal conductive channels between the source electrode and two-dimensional electron gas (2DEG) are cut by the 2DHG; the magnetic field control on the conductive channels is realized by applying voltage on the groove gate electrode so as to realize the enhancement mode; and the regulation and control on the threshold value voltage can be realized by doping parts of the conductive channels; and on the other hand, the polarization super junctions between the gate electrode and the drain electrode assist to use up a drifting region in a blocked state so as to optimize the transverse electric field distribution of the device and improve the voltage resistance of the device.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to an enhanced HEMT (High Electron Mobility Transistor, high electron mobility transistor) device. Background technique [0002] The wide-bandgap semiconductor gallium nitride (GaN) has the characteristics of high critical breakdown electric field (~3.3×106V / cm), high electron mobility (~2000cm2 / V s), and the heterojunction based on GaN material has high electron The mobility transistor (HEMT) also has a high concentration (~1013cm-2) of two-dimensional electron gas (2DEG), which makes the GaN HEMT device have the characteristics of high reverse blocking voltage, low forward conduction resistance, and high operating frequency. , Low power consumption, high voltage switching device application field has huge application prospects. [0003] For AlGaN / GaN HEMT devices, enhancement-mode (normally-off) HEMT devices have more advantages than depletion-mode (normally-on...

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Problems solved by technology

However, implanting fluorine ions in the barrier layer will cause damage to the material of the barrier layer on the one hand; on the other hand, the thinner barrier layer makes the distribution of fluorine ions difficult to control, and the fluorine ions located in the barrier layer are far away from the 2DEG trench. If the channel is very close, the concentration and mobility of electrons in the channel will be reduced, which will eventually greatly affect the current capability of the device and cause a decrease in reliability.

The literature (AkiraNakajima, et.al. "GaN-BasedSuperHeterojunctionFieldEffectTransistorsUsingthePolarizationJunctionConcept" IEEE ElectronDeviceLetters, vol.32, no.4, pp.542-544, 2011) adopts the idea of ​​a polarized superjunction, growing above the AlGaN barrier layer in the drift region A top layer of GaN, and two-dimensional hole gas (2DHG) is formed at its interface. The 2DHG and the 2DEG below form a natural "superjunction". So as to achieve the purpose of improving the withstand voltage, such as Figure 4 As shown, but the top layer of GaN and the gate electrode form an ohmic contact of holes, and when the forward conduction is conducted, the gate leakage current will be generated when the gate voltage is large, which limits the gate voltage swing.

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