Comparison of Dry Development Techniques using O2 and SO2/O2 Low-Pressure Plasmas

Pons, M.; Joubert, O.; Martinet, C.; Pelletier, Jacques; Panabiere, Jean-Pierre; Weill, A.

doi:10.1143/jjap.33.991

Cited by 21 publications

(6 citation statements)

References 16 publications

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“…7,[11][12][13][14][15][16] In situ mass spectroscopy indicated similar etch products to those obtained while etching in a pure O 2 plasma such as H 2 O, CO and CO 2 . 7,[11][12][13][14][15][16] In situ mass spectroscopy indicated similar etch products to those obtained while etching in a pure O 2 plasma such as H 2 O, CO and CO 2 .…”

Section: Literature Surveymentioning

confidence: 83%

“…Using infrared ͑IR͒ and x-ray photoelectron spectroscopy ͑XPS͒, Chou et al observed a 1 nm structurally strained oxide layer on top of polysiloxane films exposed to an O 2 plasma that reduced the etching rate of the underlying film. 7 With pure O 2 plasmas, anisotropic profiles can be attained at ϳϪ100°C. 5 Plasma etching using an O 2 -only chemistry provides the high selectivities between the Si-containing and non-Sicontaining layers required for pattern transfer, but it is accompanied with considerable lateral etching and poor CD control.…”

Section: Literature Surveymentioning

confidence: 99%

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Transfer etching of bilayer resists in oxygen-based plasmas

Mahorowala¹,

Babich²,

Lin³

et al. 2000

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Thin film imaging offers the possibility of extending 248 nm lithography to sub 150 nm resolution. We have been working on a 248 nm bilayer imaging scheme which utilizes a thin Si-containing resist on top of a thick, planarizing underlayer. The image is developed in the top layer and transferred to the underlayer via O 2 -based plasma etching. This article focuses on three aspects of the critical transfer etch process: etch resistance of the imaging resist, profile control and resist roughening. The imaging resist thickness loss is very fast during the first few seconds of the etch after which the rate diminishes. The relative importance of three phenomena that can explain this nonlinear behavior: oxidation of silicon, deprotection of resist moieties, and plasma etching of resist, are discussed. Fourier transform infrared studies on imaging resist films indicate minimal deprotection-related film thickness losses. X-ray photoelectron spectroscopy analyses of etched films indicate that the extent of surface oxidation increases initially and then becomes constant. Thus, the etching of this category of resists can be described as a combination of the oxidation of the silicon species and sputtering of the oxide-like layer formed. Post-transfer etch profiles using an O 2 plasma are shown, and methods to reduce imaging resist faceting and thickness loss either by modifying the imaging layer silicon content or by using passivating plasma chemistries are discussed. The effect of different etching chemistries and processing conditions on imaging layer roughening and striation formation on underlayer sidewalls are explained with the aid of scanning electron microscopy micrographs and atomic force microscopy images of etched feature sidewalls. It is shown that the SO 2 -O 2 etch significantly reduces the sidewall roughness from the postlithograpy values. The ϳ3.5 nm rms sidewall roughness observed postetch is comparable to postdeveloped roughness values measured for mature single layer resists. The printing of 125 nm line/space patterns and 150 nm trench features with 10:1 aspect ratios in the underlayer is also demonstrated.

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Section: Literature Surveymentioning

confidence: 83%

Section: Literature Surveymentioning

confidence: 99%

Transfer etching of bilayer resists in oxygen-based plasmas

Mahorowala¹,

Babich²,

Lin³

et al. 2000

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…Finally, low-temperature etching and associated wafer clamping can stress other film layers in integrated circuit fabrication. Based on recent reports, 7,8,14,15 we are currently investigating the effects of additives to the O 2 feed gas in the helicon in order to form anisotropic profiles at higher temperatures.…”

Section: Discussionmentioning

confidence: 99%

Profile control in dry development of high-aspect-ratio resist structures

Stern

Palmateer

Horn

et al. 1995

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

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Articles you may be interested inThree-dimensional electron-beam lithography using an all-dry resist process Dry development of sub-0.25 μm features patterned with 193 nm silylation resist Application of plasma polymerized methylsilane resist for all-dry 193 nm deep ultraviolet processing Anisotropic etching for dry development of thick resist layers in oxygen-based plasmas has been developed for two particular applications: trilayer resist for planarization of steep binary optics structures, and top surface imaged ͑silylated͒ resists for deep submicron lithography. To reduce linewidth degradation during etching of high-aspect-ratio resist structures, lateral etching and bow are minimized in two different reactors, a conventional parallel-plate reactive ion etching ͑RIE͒ system and a low-pressure, high-ion-density helicon etcher. In the conventional RIE system, C 5 H 8 , a polymer-forming gas is added to the O 2 feed gas to form a sidewall inhibition layer. In the helicon reactor, very low temperatures ͑Ϫ100°C͒ are used to suppress sidewall etching. Different optimization conditions are found for trilayer resist etching and pattern transfer of silylated resist in the helicon reactor.

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“…3,7-9 While using an O 2 -only etch chemistry gives high selectivities between the image layer and underlayer, there is considerable lateral etch and consequently poor critical dimension ͑CD͒ control which is believed to be caused by the spontaneous lateral etch by atomic oxygen. 13,14 Several gas additives to O 2 were studied in order to overcome these problems. N 2 -O 2 plasmas 5,15 and CO 2 -O 2 plasmas 5 resulted in improved linewidth control compared to O 2 -only plasmas.…”

Section: Introductionmentioning

confidence: 99%

“…7͒ improved profile quality but did not decrease lateral etching. SO 2 /O 2 mixtures were shown to provide good profiles due to formation of a sidewall passivation layer 4,5,14,16,17 along with good selectivity. However, there are potential manufacturing issues with SO 2 as the sulfur-containing passivation layers form sulfur-based acids upon exposure to moisture.…”

Section: Introductionmentioning

confidence: 99%

Etching silicon-containing bilayer resists in ammonia-based plasmas

Panda¹,

Wise²,

Mahorowala³

et al. 2005

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

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The need to print smaller feature sizes has led to the shift from 248nmto193nm lithography. The disadvantages of 193nm ArF single-layer resist materials, such as lower depth of focus and lower etch resistance, have made thin-film imaging (TFI) techniques an attractive alternative. In the bilayer (comprised of an image layer and an underlayer) approach, a form of TFI, O2-based plasma chemistries are used for the transfer etches whereby oxidation of silicon in the image layer provides the required etch resistance. However, use of oxygen results in profile and critical dimension (CD) control issues. While gas additives have helped minimize these problems, there are other accompanying disadvantages. In this work, the feasibility of a non-O2-containing NH3-based plasma etch chemistry was evaluated. Effects of additive gases, such as N2, H2, and C2H4, were investigated. Surface analysis of the resist showed that nitrogen from the gas phase was incorporated in the surface of the image layer during the etch, and the etch resistance increased with this nitrogen content. Gas phase analysis showed that the relative N2H species density in the system was correlated with the nitrogen incorporated in the image layer, and is thus believed to govern the etch resistance of the image layer. The underlayer etch behavior was correlated with that of the atomic hydrogen species density. The effect of the additives on the cross section profiles and line edge roughness were studied. The highest CD biases were obtained with H2 as the additive, while near-zero CD biases were attained with C2H4 as the additive. Also, with the C2H4 additive, minimum line edge roughness and smoothest profiles were obtained.

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Comparison of Dry Development Techniques using O₂ and SO₂/O₂ Low-Pressure Plasmas

Cited by 21 publications

References 16 publications

Transfer etching of bilayer resists in oxygen-based plasmas

Transfer etching of bilayer resists in oxygen-based plasmas

Profile control in dry development of high-aspect-ratio resist structures

Etching silicon-containing bilayer resists in ammonia-based plasmas

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