High quality of N-polar GaN film fabricated by layer transfer technology using high selective material removal rate of CMP

Yu, Zicheng; Zhang, Li; Yu, Guo; Deng, Xuguang; Jiang, Chunyu; Tang, Wenxin; Yin, Haotian; Liu, Weining; Chen, Zhang; Zhang, Baoshun

doi:10.1016/j.mssp.2021.106440

Cited by 4 publications

(4 citation statements)

References 26 publications

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“…The on-resistance (R ON ) values of CMP and ICP sample are 6.51 Ω•mm and 8.87 Ω•mm, respectively. The improved output characteristics of the CMP sample are mainly due to the reduced deeplevel states defects induced by energetic ion bombardment [15]. Notably, it was found that the output curves shown in Figure 5b show negligible self-heating effects, i.e., current drop at the operating conditions of high I DS = 756.1 mA/mm and high V DS = 15 V. The improved thermal dissipation abilities of our device can be attributed to the layers having the worst thermal conductivity, i.e., high-Al-content AlGaN buffers having been totally removed by the CMP/ICP etching process [20].…”

Section: Resultsmentioning

confidence: 99%

“…Based on this method, an N-polar HEMT with the maximum drain current (I D ) of ~600 mA/mm was realized [13]. Our group also reported a high-selectivity etching process of N-polar AlGaN to GaN using chemical-material polishing (CMP), delivering a N-polar GaN surface with a roughness as low as 0.307 nm, and photoluminescence spectroscopy results indicated reduced deep level states in the CMP-fabricated sample, probably owing to the absent of ion bombardment [15], providing an approach to preparing N-polar GaN structrues through the ELT method.…”

Section: Introductionmentioning

confidence: 97%

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High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

Guo,

Yu,

Zhang

et al. 2024

Crystals

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This article presents the utilization of the chemical–mechanical polishing (CMP) method to fabricate high-performance N-polar GaN/AlGaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) through layer transfer technology. The nucleation and buffer layers were removed via CMP to attain a pristine N-polar GaN surface with elevated smoothness, featuring a low root-mean-square (RMS) roughness of 0.216 nm. Oxygen, carbon, and chlorine impurity elements content were low after the CMP process, as detected via X-ray photoelectron spectroscopy (XPS). The electrical properties of N-polar HEMTs fabricated via CMP exhibited a sheet resistance (Rsh) of 244.7 Ω/sq, a mobility of 1230 cm2/V·s, and an ns of 2.24 × 1013 cm−2. Compared with a counter device fabricated via inductively coupled plasma (ICP) dry etching, the CMP devices showed an improved output current of 756.1 mA/mm, reduced on-resistance of 6.51 Ω·mm, and a significantly reduced subthreshold slope mainly attributed to the improved surface conditions. Meanwhile, owing to the MIS configuration, the reverse gate leakage current could be reduced to as low as 15 μA/mm. These results highlight the feasibility of the CMP-involved epitaxial layer transfer (ELT) technique to deliver superior N-polar GaN MIS-HEMTs for power electronic applications.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

Guo,

Yu,

Zhang

et al. 2024

Crystals

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“…Alternatively, Yu et al chose to remove N-polar buffer layers by selectively chemical mechanical polishing (CMP), with a selection ratio as high as 35: 1 (Al x Ga 1-x N: GaN = 1400 nm/min: 40 nm/min). Although the surface roughness of the prepared N-polar GaN reached 0.31nm, mechanical scratches can be obviously seen on the surface of the material [14]. However, up to now, the cause of such a surface difference in the ICP etching of N-and Ga-polar layers is not clear, and the etched surface could not not be optimized well at a good time cost.…”

Section: Introductionmentioning

confidence: 93%

“…However, the growth of devicelevel high quality N-polar nitride materials is rather challenging which requires a much higher growth temperature [10], relatively low V/III ratio [11], and miscut substrates [12] in order to suppress oxygen impurity incorporation and surface hillocks. Alternative approach is to fabricate devices on the backside of a Ga-polar thin film through substrate removal [13] and layer transfer [14,15]. This method can provide high crystalline N-polar materials and enables the possibility of fabricating N-polar devices on large scale Si substrates, promising for low-cost and mass production.…”

Section: Introductionmentioning

confidence: 99%

Study of dry etched N-polar (Al)GaN surfaces obtained by inductively coupled plasma etching

Yin²,

Zeng³

et al. 2022

Front. Phys.

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We report the Cl-based inductively coupled plasma etching of N-polar Al(Ga)N layers obtained from layer transfer. It is found that debris appeared on the etched N-polar surface after exposing in air for a short period whereas the etched Al-/Ga-polar surface was clean and smooth. The debris can be completely self-vanished on the N-polar Al0.4Ga0.6N surface after exposing in air for a few hours but still remained on the N-polar GaN surface even after over 1 month. The surface chemical analysis results suggested that the debris is the result of Cl-related byproduct generated during the etching process. Byproducts like Al(Ga)Clx and its derivatives are believed to cover on the N-polar surface after the inductively coupled plasma etching and increase the etched surface roughness significantly. The formation and disappearance of debris are attributed to the formation of Al(Ga)Clx⋅ 6H2O crystals when Al(Ga)Clx absorbs moisture in the air and its spontaneous decomposition on the N-polar surface, respectively. Adding O2/SF6 in the process helps remove Al(Ga)Clx byproducts but at the cost of roughened surface/reduced etch rate. With an additional cleaning process after etching, an uniform and smooth N-polar GaN surface with a low root-mean-square surface roughness of 0.5–0.6 nm has been successfully obtained at a reasonable etch rate (∼150 nm/min). The results can provide valuable guidance for the fabrication of high-performance N-polar GaN devices.

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Wafer-scale N-polar GaN heterogeneous structure fabricated by surface active bonding and laser lift-off

Tian,

Gao,

Wang

et al. 2024

Journal of Alloys and Compounds

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High quality of N-polar GaN film fabricated by layer transfer technology using high selective material removal rate of CMP

Cited by 4 publications

References 26 publications

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

Study of dry etched N-polar (Al)GaN surfaces obtained by inductively coupled plasma etching

Wafer-scale N-polar GaN heterogeneous structure fabricated by surface active bonding and laser lift-off

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