Nanocrystalline diamond capped AlGaN/GaN high electron mobility transistors via a sacrificial gate process

Abstract

Top-side integration of nanocrystalline diamond films in the fabrication sequence of AlGaN/GaN high electron mobility transistors is demonstrated. Reliable oxygen plasma etching of the diamond capping layer, required for a diamond-before-gate process, was implemented by using a sacrificial SiN "dummy" gate. Hall characterization showed minimal ($6%) reduction in sheet carrier density and commensurate increase in sheet resistance, while maintaining mobility and on-state drain current density. Off-state drain current and threshold voltage were increased, likely by fluorination of the AlGaN surface after removal of the sacrificial gate, even though a 20 nm thick Al 2 O 3 layer was used as a SF 6 -plasma etch stop. Pulsed I DS and on-resistance were improved, indicating that a 10 nm SiN/ 500 nm NCD could offer improved AlGaN surface passivation compared to a more conventional 100 nm thick PECVD SiN film.

High reverse breakdown voltage Schottky rectifiers without edge termination on Ga2O3

“…2,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] It has a high theoretical breakdown electric field ($8 MV/ cm), leading to a Baliga figure-of-merit almost four times higher than that for GaN. 2,11,15 Experimentally obtained breakdown field values up to 3.8 MV/cm in Sn-doped Ga 2 O 3 metal-oxide-semiconductor field-effect transistors (MOSFETs) grown by Metal Organic Chemical Vapor Deposition (MOCVD) on (100) semi-insulating substrates are already higher than the bulk critical field strengths of both GaN and SiC. 16 Power Ga 2 O 3 Schottky diode rectifiers, metal-semiconductor field-effect transistors (MESFETs), and metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on either bulk or thin film b-Ga 2 O 3 have been reported.…”

“…16 Power Ga 2 O 3 Schottky diode rectifiers, metal-semiconductor field-effect transistors (MESFETs), and metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on either bulk or thin film b-Ga 2 O 3 have been reported. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] The MOSFETs exhibited breakdown voltages >750 V with field-plate edge termination. 19 Schottky rectifiers are ideal devices for establishing material quality and have fast switching speed and low onstate losses, and as unipolar devices, they are good candidates for high power and high frequency applications because they do not suffer from minority-carrier storage effects that limit the switching speed.…”

Surface‐Oxide‐Controlled InAlGaN/GaN High‐Electron‐Mobility Transistors Using Al2O3‐Based Insulated‐Gate Structures with H2O Vapor Pretreatment

“…As shown in Table 2, the remarkable decrease in the mobility at the gate region of the Schottky-HEMT is attributed to the effect of plasma damage during the dry etching of the SiN passivation films. [43] Alternatively, in the case of MIS-HEMT, mobility degradation can be suppressed by depositing Al 2 O 3 films on the InAlGaN surface that functions as an etching stopper for SiN [44,45] ; moreover, the InAlGaN surface was prevented from exposure to the SF 6 plasma, leading to the improvement in I dmax .…”

Thermal Management of GaN-on-Si High Electron Mobility Transistor by Copper Filled Micro-Trench Structure

“…Composite substrates 15 and flip-chip bonding with epoxy under fill 16 methods have been implemented to decrease thermal impedance on the whole wafer; however, the problem of hot spots in the device channel region continues to exist. In other studies, several approaches towards suppression of the self-heating effect have been investigated, such as substrate transfer 17,18 and heat spreading using nanocrystalline diamondon the top surface of the device 19,20 . However, devices using these methods have shown moderate performance.…”