Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

Perros, Alexander Pyymaki; Bosund, Markus; Sajavaara, Timo; Laitinen, Mikko; Sainiemi, Lauri; Huhtio, Teppo; Lipsanen, Harri

doi:10.1116/1.3664306

Cited by 13 publications

(16 citation statements)

References 25 publications

(31 reference statements)

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“…85,86 The piezoelectric properties of AlN 87 have additionally made it of interest as a transducer material in surface acoustic wave and NEM devices. 43,88 The high resistance of AlN to fluorinated plasmas 89 has further lead to its use as a plasma etch stop, 33 hard mask, 90,91 and Cu capping layer 33 in microelectronic device applications.…”

Section: Ecs Journal Of Solid State Science and Technology 6 (10) N1mentioning

confidence: 99%

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

ECS J. Solid State Sci. Technol.

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Atomic layer deposited (ALD) high-dielectric-constant (high-k) materials have found extensive applications in a variety of electronic, optical, optoelectronic, and photovoltaic devices. While electrical, optical, and interfacial properties have been the primary consideration for such devices, thermal and mechanical properties are becoming an additional key consideration for many new and emerging applications of ALD high-k materials in electromechanical, energy storage, and organic light emitting diode devices. Unfortunately, a clear correspondence between thermal/mechanical and electrical/optical properties in ALD high-k materials has yet to be established, and a detailed comparison to conventional silicon-based dielectrics to facilitate optimal material selection is also lacking. In this regard, we have conducted a comprehensive investigation and review of the thermal, mechanical, electrical, optical, and structural properties for a series of prevalent and emerging ALD high-k materials including aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), hafnium oxide (HfO 2 ), and beryllium oxide (BeO). For comparison, more established silicon-based dielectrics were also examined, including thermally grown silicon dioxide (SiO 2 ) and plasma-enhanced chemically vapor deposited hydrogenated silicon nitride (SiN:H). We find that in addition to exhibiting high values of dielectric permittivity and electrical resistance that exceed those of SiO 2 and SiN:H, the ALD high-k materials exhibit equally exceptional thermal and mechanical properties with coefficients of thermal expansion ≤ 6 × 10 -6 / • C, thermal conductivites (κ) of 3-15 W/m K, and Young's modulus and hardness values exceeding 200 and 25 GPa, respectively. In many cases, the observed extreme thermal/mechanical properties correlate with the presence of crystallinity in the ALD high-k films. In contrast, some of the electrical and optical properties correlate more strongly with the percentage of ionic vs. covalent bonds present in the high-k film. Overall, the ALD high-k dielectrics investigated concurrently exhibit compelling thermal/mechanical and electrical/optical properties. The drive to reduce gate leakage currents in highly scaled complementary metal-oxide-semiconductor (CMOS) transistors has led to the exploration and development of a wide variety of high-dielectricconstant (high-k) materials to replace silicon dioxide (SiO 2 ) as the insulating gate dielectric material.1-8 Many of these same high-k materials have found additional applications in future non-CMOS logic and memory storage products such as solid-state electrolytes in resistive switching devices, 9,10 tunnel barriers in spin-transport devices, 11 and as a ferroelectric in magnetoelectric devices. While electrical, physical, and thermodynamic properties have clearly been a key consideration in all of the above applications, thermal properties have become an additional important consideration for higk-k dielectrics as aggressive dimensional scaling of devices has created the need to dissipate ...

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Section: Ecs Journal Of Solid State Science and Technology 6 (10) N1mentioning

confidence: 99%

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

ECS J. Solid State Sci. Technol.

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“…In [7] it was reported that AlN mask provided very high selectivity to SiO 2 when the gas composition of C 4 F 8 /SF 6 mixture, pressure and bias power are properly tuned. Similarly, in [8] it was reported that in ICP-RIE system with SF 6 /O 2 plasma, the etch rate of AlN can be brought down to 1 nm/min. Though both paper results were obtained only with blanket wafers without any mask pattern, they are a good hint for researches to continue process development in this direction.…”

Section: Introductionmentioning

confidence: 82%

Deep SiO₂etching with Al and AlN masks for MEMS devices

Bliznetsov

Lin

Zhang

et al. 2015

J. Micromech. Microeng.

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Silicon oxide-based materials such as quartz and silica are widely used in Microelectromechanical Systems (MEMS). One way to enhance capability of their deep plasma etching is to increase selectivity by the use of hard masks. Though this approach was studied previously, information on the use of hard masks for etching of silicon-oxide based materials on 200 mm substrates is scarce. We present results of etching process development for amorphous silicon oxide using Al and AlN masks with a view of application of results for etching of silica and quartz. Three gas chemistries (C 4 F 8 /O 2 , CF 4 and SF 6 ) and their mixtures were compared in an industrial reactive ion etch (RIE) chamber with two plasma sources. It was established that pure SF 6 is the best etchant and AlN is better mask than Al for providing higher selectivity and sidewall angle close to vertical. A range of etching parameters for micromasking-free etching was established and etched structures of up to 4:1 aspect ratio were created in 21m-thick oxide using the process with etch rate of 0.32-0.36 m/min and selectivity to AlN mask of (38-49):1.

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“…After AlN deposition, the bulge test samples were fabricated using through wafer etching of silicon, as shown in this process results in samples with free-standing AlN membranes. The etch process used has a high selectivity between Al 2 O 3 and Si [35], and a low etch rate for AlN [36]. After DRIE, the samples were released and cleaned in acetone and isopropanol baths.…”

Section: Sample Fabricationmentioning

confidence: 99%

Mechanical properties and reliability of aluminum nitride thin films

Österlund

Kinnunen

Rontu

et al. 2019

Journal of Alloys and Compounds

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Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

Cited by 13 publications

References 25 publications

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Deep SiO₂etching with Al and AlN masks for MEMS devices

Mechanical properties and reliability of aluminum nitride thin films

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Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

Cited by 13 publications

References 25 publications

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Deep SiO2etching with Al and AlN masks for MEMS devices

Mechanical properties and reliability of aluminum nitride thin films

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Deep SiO₂etching with Al and AlN masks for MEMS devices