New Dry-Etch Chemistries for III-V Semiconductors

1993 ◽  
Vol 334 ◽  
Author(s):  
S. J. Pearton ◽  
U. K. Chakrabarti ◽  
F. Ren ◽  
C. R. Abernathy ◽  
A. Katz ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Pattern Transfer ◽  
Metal Contacts ◽  
Arrhenius Behavior ◽  
Device Structures ◽  
Sample Position ◽  
Via Hole ◽  
Etch Rates ◽  
Dry Etch ◽  
Inp Substrates

AbstractFor some dry etching applications in III-V semiconductors, such as via hole formation in InP substrates, the currently used plasma chemistries have etch rates that are up to a factor of 30 too slow. We report on the development of 3 new classes of discharge chemistries, namely C12/CH4 /H2/Ar at 150°C (yielding InP etch rates of >1 μm · min−1 at 1 mTorr and –80V dc), HBr/H2 for selective etching of InGaAs over AlInAs, and iodine-based plasmas (HI/H2, CH3 I/H2) that offer rapid anisotropic etching of all III-V materials at room temperature. In all cases, Electron Cyclotron Resonance sources (either multipolar or magnetic mirror) with additional rf biasing of the sample position are utilized to obtain low damage pattern transfer processes that generally use metal contacts on device structures as self-aligned etch masks. The temperature dependence of etch rates with these new chemistries display non-Arrhenius behavior in the range 50-250°C and a detailed study of the phenomenon are reported. Electrical, optical and chemical analysis of the etched surfaces show that it is possible to achieve essentially damage-free pattern transfer.

Patterning of LiGaO2 and LiAlO2 by Wet and Dry Etching

1996 ◽  
Vol 449 ◽  
Author(s):  
J. W. Lee ◽  
S. J. Pearton ◽  
C. R. Abernathy ◽  
R. G. Wilson ◽  
B. L. Chai ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
High Selectivity ◽  
Electron Cyclotron Resonance ◽  
Dry Etching ◽  
Electron Cyclotron ◽  
Acid Solutions ◽  
Lattice Constants ◽  
Etch Rates ◽  
Dry Etch

ABSTRACTLiGaO2 and LiAlO2 have similar lattice constants to GaN, and may prove useful as substrates for III-nitride epitaxy. We have found that these materials may be wet chemically etched in a number of acid solutions, including HF, at rates between 150–40,000 Å/min. Dry etching with SF6/Ar plasmas provides faster rates than Cl2/Ar or CH4/H2/Ar under Electron Cyclotron Resonance conditions, indicating the fluoride etch products are more volatile that their chloride or metalorganic/hydride counterparts. Dry etch rates are low ( < 2, 000 Å/min), providing high selectivity (>5) over the nitrides. The incorporation of hydrogen in these materials is also of interest because this could provide a reservoir of hydrogen that may passivate dopants in overlying nitride films. In 2H implanted samples, 50 % of the deuterium is lost by evolution from the surface by annealing at 400 °C for 20 min and all of the deuterium is gone at 700°C. The diffusivity of 2H is ∼10-13 cm2/s at 250°C in LiA1O2, approximately two orders of magnitude higher than in LiGaO2.

Self-Aligned, Metal-Masked Dry Etch Processing of III-V Electronic and Photonic Devices

1992 ◽  
Vol 260 ◽  
Author(s):  
S. J. Pearton ◽  
A. Katz ◽  
A. Feingold ◽  
F. Ren ◽  
T. R. Fullowan ◽  
...  
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Electron Cyclotron Resonance ◽  
Photonic Devices ◽  
Bipolar Transistors ◽  
Metal Contacts ◽  
Ecr Plasma ◽  
In Situ Fabrication ◽  
Device Processing ◽  
Integrated Processing ◽  
Dry Etch

ABSTRACTElectron Cyclotron Resonance (ECR) plasma etching of a variety of III-V devices, including heterojunction bipolar transistors (HBTs), and lasers will be reviewed. In many of these devices, the metal contacts also perform as self-aligned, dry etch masks, so that mask erosion must be addressed. Sidewall smoothness is also an issue for most etched mesa lasers, and conditions for achieving the requisite smoothness will be discussed. The use of stencil masks for pattern transfer of large (∼100μm) features during cluster-tool, single wafer integrated processing raises the possibility of a completely in-situ fabrication technology without the need for lithography. The dry etching of a variety of ohmic and Schottky metallizations and also of dielectrics deposited in a low pressure, rapid thermal CVD system lays the foundation for integrated III-V device processing.

Comparison Of Dry-Etch Techniques For Gan, Inn, And Ain

1997 ◽  
Vol 483 ◽  
Author(s):  
R. J. Shul ◽  
G. A. Vawter ◽  
C. G. Willison ◽  
M. M. Bridges ◽  
J. W. Lee ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Electron Cyclotron Resonance ◽  
Ion Beam ◽  
High Plasma ◽  
Group Iii ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Etch Rates ◽  
Group Iii Nitride ◽  
Dry Etch

AbstractFabrication of group-III nitride devices relies on the ability to pattern features to depths ranging from ∼1000 Å to > 5 μm with anisotropic profiles, smooth morphologies, selective etching of one material over another, and a low degree of plasma-induced damage. In this study, GaN etch rates and etch profiles are compared using reactive ion etch (RIE), reactive ion beam etching (RIBE), electron cyclotron resonance (ECR), and inductively coupled plasma (ICP) etch systems. RIE yielded the slowest etch rates and sloped etch profiles despite dc-biases > −900 V. ECR and ICP etching yielded the highest rates with anisotropic profiles due to their high plasma flux and the ability to control ion energies independently of plasma density. RIBE etch results also showed anisotropic profiles with slower etch rates than either ECR or ICP possibly due to lower ion flux. InN and AIN etch characteristics are also compared using ICP and RIBE.

Comparison of Novel Chlorine, Bromine and Iodine Plasma Chemistries for Anisotropic Trench Etching In GaN, InN and Ain

1998 ◽  
Vol 512 ◽  
Author(s):  
Hyun Cho ◽  
T. Maeda ◽  
J. D. MacKenzie ◽  
S. M. Donovan ◽  
C. R. Abemathy ◽  
...  
Keyword(s):  
Pattern Transfer ◽  
Inductively Coupled Plasmas ◽  
Inductively Coupled ◽  
Etch Rates ◽  
Coupled Plasmas

ABSTRACTAnisotropic pattern transfer has been performed for GaN, InN and AIN in Cl2/Ar, BI3/Ar and BBr3/Ar Inductively Coupled Plasmas(ICP). Controlled etch rates in the range of 500–1500Å·min−1 are obtained for III-nitride materials in Cl2/Ar chemistry. Etch selectivities of 100:1 were achieved for InN over both GaN and AIN in the BI3 mixtures, while for BBr3 discharges values of 100:1 for InN over AIN and 25:1 for InN over GaN were measured.

scholarly journals Processing Challenges for GaN-Based Photonic and Electronic Devices

1997 ◽  
Vol 468 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
R. J. Shul ◽  
J. C. Zolper ◽  
A. Katz
Keyword(s):  
Recent Work ◽  
Ohmic Contacts ◽  
Large Diameter ◽  
High Temperature Electronics ◽  
Conductivity Type ◽  
Etch Rates ◽  
P Type ◽  
Recessed Gate ◽  
Dry Etch ◽  
Physical And Chemical

ABSTRACTThe wide gap materials SiC, GaN and to a lesser extent diamond are attracting great interest for high power/high temperature electronics. There are a host of device processing challenges presented by these materials because of their physical and chemical stability, including difficulty in achieving stable, low contact resistances, especially for one conductivity type, absence of convenient wet etch recipes, generally slow dry etch rates, the high temperatures needed for implant activation, control of suitable gate dielectrics and the lack of cheap, large diameter conducting and semi-insulating substrates. The relatively deep ionization levels of some of the common dopants (Mg in GaN; B, Al in SiC; P in diamond) means that carrier densities may be low at room temperature even if the impurity is electrically active - this problem will be reduced at elevated temperature, and thus contact resistances will be greatly improved provided the metallization is stable and reliable. Some recent work with CoSix on SiC and W-alloys on GaN show promise for improved ohmic contacts. The issue of unintentional hydrogen passivation of dopants will also be covered - this leads to strong increases in resistivity of p-SiC and GaN, but to large decreases in resistivity of diamond. Recent work on development of wet etches has found recipes for AlN (KOH), while photochemical etching of SiC and GaN has been reported. In the latter cases p-type materials is not etched, which can be a major liability in some devices. The dry etch results obtained with various novel reactors, including ICP, ECR and LE4 will be compared - the high ion densities in the former techniques produce the highest etch rates for strongly-bonded materials, but can lead to preferential loss of N from the nitrides and therefore to a highly conducting surface. This is potentially a major problem for fabrication of dry etched, recessed gate FET structures.

Low Bias Dry Etching of Sic and Sicn in ICP NF3 Discharges

1998 ◽  
Vol 512 ◽  
Author(s):  
J. J. Wang ◽  
Hyun Cho ◽  
E. S. Lambers ◽  
S. J. Peartont ◽  
M. Ostling ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Ion Flux ◽  
Pattern Transfer ◽  
Plasma Composition ◽  
Source Power ◽  
Ion Energy ◽  
Trade Off ◽  
Inductively Coupled ◽  
Extensive Surface ◽  
Etch Rates

ABSTRACTA parametric study of the etching characteristics of 6H p+ and n+ SiC and thin film SiC0.8N0.2 in Inductively Coupled Plasma NF3/O2 and NF3/Ar discharges has been performed. The etch rates in both chemistries increase monotonically with NF3 percentage and rf chuck power reaching 3500Å·min−1 for SiC and 7500 Å·min−1 for SiCN. The etch rates go through a maximum with increasing ICP source power, which is explained by a trade-off between the increasing ion flux and the decreasing ion energy. The anisotropy of the etched features is also a function of ion flux, ion energy and atomic fluorine neutral concentration. Indium-tinoxide( ITO) masks display relatively good etch selectivity over SiC(maximum of 70:1) while photoresist etches more rapidly than SiC. The surface roughness of SiC is essentially independent of plasma composition for NF3/O2 discharges, while extensive surface degradation occurs for SiCN under high NF3:O2 conditions. The high ion flux available in the ICP tool allows etching even at very low dc self-biases, ≤ −10V, leading to very low damage pattern transfer.

Electron Cyclotron Resonance Plasma Processing of GaAs-AlGaAs Hemt Structures

1991 ◽  
Vol 240 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
J. R. Lothian ◽  
T. R. Fullowan ◽  
R. F. Kopf ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Complete Removal ◽  
Pattern Transfer ◽  
Hydrogen Passivation ◽  
Ion Energy ◽  
Ion Energies ◽  
Resonance Plasma ◽  
Or Gate

ABSTRACTThe damage introduced into GaAs/AlGaAs HEMT structures during pattern transfer (O2 plasma etching of the PMGI layer in a trilevel resist mask) or gate mesa etching (CCl2F2/O2 or CH4/H2/Ar etching of GaAs selectively to AlGaAs) has been studied. For etching of the PMGI, the threshold O+ ion energy for damage introduction into the AlGaAs donor layer is ∼200 eV. This energy is a function of the PMGI over-etch time. The use of ECR-RF O2 discharges enhances the PMGI etch rate without creating additional damage to the device. Gate mesa etching produces measurable damage in the underlying AlGaAs at DC negative biases of 125–150V. Substantial hydrogen passivation of the Si dopants in the AlGaAs occurs with the CH4 /H2 /Ar mixture. Recovery of the initial carrier concentration in the damaged HEMT occurs at ∼400°C, provided the maximum ion energies were dept to ≤400 eV. Complete removal of residual AIF3 on the CCl2F2/O2 exposed AlGaAs was obtained after H2O and NH4 OH:H2O rinsing while chlorides were removed by H2O alone.

Comparison of Microwave ECR and RF Plasmas for Dry Etching of Single Crystal 6H-SiC

1994 ◽  
Vol 339 ◽  
Author(s):  
J. R. Flemish ◽  
K. Xie ◽  
W. Buchwald ◽  
L. Casas ◽  
J. H. Zhao ◽  
...  
Keyword(s):  
Single Crystal ◽  
Plasma Etching ◽  
Electron Cyclotron Resonance ◽  
Schottky Diodes ◽  
Substrate Bias ◽  
Rf Plasmas ◽  
Ecr Plasma ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Etch Rates

ABSTRACTElectron cyclotron resonance (ECR) plasma etching of single crystal 6H-SiC has been investigated using a CF4/O2 gas mixture and compared to conventional reactive ion etching (RIE) in a radio frequency (13.56 MHz) reactor. The use of ECR results in higher etch rates, lower levels of bias and smoother etched surfaces than rf-RIE. ECR etch rates exceeding 100 nm/min have been obtained at a substrate bias of-100 V. Etch rate and surface morphology have been studied as a function of pressure, bias and power. Auger electron spectroscopy shows that ECR etching leaves no residues unlike rf-RIE which leaves residues containing Al, F, O and C. The current-voltage and capacitance-voltage measurements of Schottky diodes show that there is far less damage induced by ECR etching compared to rf-RIE.

Comparison of ICl and IBr for Dry Etching of III-Nitrides

1996 ◽  
Vol 449 ◽  
Author(s):  
C. B. Vartuli ◽  
J. W. Lee ◽  
J. D. MacKenzie ◽  
S. J. Pearton ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Silicon Dioxide ◽  
Microwave Power ◽  
Etch Rate ◽  
Product Formation ◽  
Bond Breaking ◽  
Weakly Bound ◽  
Preferential Loss ◽  
Etch Rates ◽  
Dry Etch

ABSTRACTICl/Ar ECR discharges provide the fastest dry etch rates reported for GaN, 1.3 µm/min. These rates are much higher than with Cl2/Ar, CH4/H2/Ar or other plasma chemistries. InN etch rates up to 1.15 µm/min and 0.7 µm/min for In0.5Ga0.5N are obtained, with selectivities up to 5 with no preferential loss of N at low rf powers and no significant residues remaining. The rates are much lower with IBr/Ar, ranging from 0.15 µm/min for GaN to 0.3 µm/min for InN. There is little dependence on microwave power for either chemistry because of the weakly bound nature of IC1 and IBr. In all cases the etch rates are limited by the initial bond breaking that must precede etch product formation and there is a good correlation between materials bond energy and etch rate. The fact that low microwave power can be employed is beneficial from the viewpoint that photoresist masks are stable under these conditions, and there is no need for use of silicon nitride or silicon dioxide. Selectivities for GaN over A1N with IC1 and IBr are still lower than with Cl2- only.

Ultraviolet light enhancement of Ta[sub 2]O[sub 5] dry etch rates

2000 ◽  
Vol 18 (1) ◽  
pp. 293 ◽  
Author(s):  
K. P. Lee ◽  
H. Cho ◽  
R. K. Singh ◽  
S. J. Pearton ◽  
C. Hobbs ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Light Enhancement ◽  
Etch Rates ◽  
Dry Etch
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