Cryogenic etching of deep narrow trenches in silicon

Aachboun, S.; Ranson, P.; Hilbert, Claude; Boufnichel, Mohamed

doi:10.1116/1.582434

Cited by 63 publications

(35 citation statements)

References 7 publications

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“…The deformations calculated for three different wafer thicknesses according the equation above are presented in Table V. The calculated values are in good agreement with the deformations measured by Aachboun et al 23 The deformation of the wafer induces new stresses into the photoresist which is already under the stress caused by the CTE mismatch. To clarify if the wafer deformation caused by the cooling system plays a role in photoresist cracking, 1.5 m thick AZ 5214 E photoresist layer was patterned on three wafers with different thicknesses of 250, 525, and 1000 m.…”

Section: Cracking Mechanisms Of Photoresistsupporting

confidence: 76%

Mask material effects in cryogenic deep reactive ion etching

Sainiemi¹,

Franssila²

2007

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inCryogenic silicon etching in inductively coupled SF 6 /O 2 plasma has been studied, especially the behavior of mask materials. Suitability of eight different mask materials for cryogenic silicon deep reactive ion etching has been investigated. Three of the five photoresists suffered from cracking during cryogenic etching. We clarified the stages of the etching process and identified two mechanisms behind the cracking: thermal expansion mismatch and mechanical deformation from wafer clamping and backside helium pressure. Also thickness of the photoresist plays a role in cracking, but, contrary to common conception that all thick resists suffer from cracking in cryogenic etching, we found that SU-8 negative resist did not crack, even for very thick layers. This is explained to be due to its high cross-linking density. All three hard mask materials had high selectivities and were free of cracking problems. However, aluminum mask resulted in poor surface quality, while thermally grown SiO 2 and amorphous Al 2 O 3 deposited by atomic layer deposition showed smooth surfaces and sidewalls. Silicon dioxide had selectivity of 150:1, while Al 2 O 3 selectivity was 66 000:1. This extreme selectivity of Al 2 O 3 mask, combined with good surface quality, is shown to be highly beneficial in both shallow and through-wafer etching.

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Section: Cracking Mechanisms Of Photoresistsupporting

confidence: 76%

Mask material effects in cryogenic deep reactive ion etching

Sainiemi¹,

Franssila²

2007

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…This film can be created by use of gases that e.g. form stable non-volatile carbon halogen materials [20], trapping volatile silicon products at the trench walls by cryogenic cooling [21], using gases (e.g. C 4 F 8 ) that form polymeric barrier layers [22] and erosion/re-deposition of mask materials such as metal halogens.…”

Section: Plasma Processing For Development Of Nanoelectronicsmentioning

confidence: 99%

Plasma etch technologies for the development of ultra-small feature size transistor devices

Borah¹,

Shaw²,

Rasappa³

et al. 2011

J. Phys. D: Appl. Phys.

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The advances in information and communication technologies have been largely predicated around the increases in computer processor power derived from the constant miniaturization (and consequent higher density) of individual transistors. Transistor design has been largely unchanged for many years and progress has been around scaling of the basic CMOS device. Scaling has been enabled by photolithography improvements (i.e. patterning) and secondary processing such as deposition, implantation, planarization, etc. Perhaps the most important of the secondary processes is the plasma etch methodology whereby the pattern created by lithography is ‘transferred’ to the surface via a selective etch to remove exposed material. However, plasma etch technologies face challenges as scaling continues. Maintaining absolute fidelity in pattern transfer at sub-16 nm dimensions will require advances in plasma technology (plasma sources, chamber design, etc) and chemistry (etch gases, flows, interactions with substrates, etc). In this paper, we illustrate some of these challenges by discussing the formation of ultra-small device structures from the directed self-assembly of block copolymers (BCPs) where nanopatterns are formed from the micro-phase separation of the system. The polymer pattern is transferred by a double etch procedure where one block is selectively removed and the remaining block acts as a resist pattern for silicon pattern transfer. Data are presented which shows that highly regular nanowire patterns of feature size below 20 nm can be created using etch optimization techniques and in this paper we demonstrate generation of crystalline silicon nanowire arrays with feature sizes below 8 nm. BCP techniques are demonstrated to be applicable from these ultra-small feature sizes to 40 nm dimensions. Etch profiles show rounding effects because etch selectivity in these nanoscale resist patterns is limited and the resist thickness rather low. The nanoscale nature of the topography generated also places high demands on developing new etch processes.

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“…Both steps repeat until complete etching of the silicon layer is accomplished. Experiments and optimization settings for anisotropic plasma etching with ICP system have been reported (Aachboun and Ranson 1999;Aachboun et al 2000).…”

Section: Investigation Of Icp Isotropic Plasma Etching For Beam Releasementioning

confidence: 99%

Micromachined SiO2 microcantilever for high sensitive moisture sensor

Chen¹,

Fang²,

Ji³

et al. 2007

Microsyst Technol

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Ultra-sensitive and selective moisture sensors are needed in various industries for processing control or environmental monitoring. As an outstanding sensor platform, surface-stress sensing microcantilevers have potential application in moisture detection. To enlarge the deflection of the microcantilever under surface stress induced by specific reactions, a new SiO 2 microcantilever is developed which features a much lower Young's modulus than conventional Si or SiN x microcantilevers. For comparing SiO 2 cantilever with Si cantilevers, a model of the cantilever sensor is given by using both analysis and simulation, resulting in good agreement with the experimental data. The results demonstrate the SiO 2 cantilever can achieve a much higher sensitivity than the Si cantilever. In order to fabricate this device, a new fabrication process using isotropic combined with anisotropic dry etching to release the SiO 2 microcantilever beam by ICP (Inductively Coupled Plasma) was developed and investigated. This new process not only obtains a high etch rate at 9.1 lm/min, but also provides good profile controllability, and a flexibility of device design. Attributed to the high sensitivity, a significant deflection amplitude of the surface modified SiO 2 microcantilever was observed upon exposure to 1% relative humidity. The SiO 2 cantilevers are promising for inexpensive and highly sensitive moisture detection.

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Cryogenic etching of deep narrow trenches in silicon

Cited by 63 publications

References 7 publications

Mask material effects in cryogenic deep reactive ion etching

Mask material effects in cryogenic deep reactive ion etching

Plasma etch technologies for the development of ultra-small feature size transistor devices

Micromachined SiO2 microcantilever for high sensitive moisture sensor

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