Plasma etching characteristics of chromium film and its novel etching mode

Nakata, H.; Nishioka, Kunio; Abe, Haruhiko

doi:10.1116/1.570669

Cited by 47 publications

(23 citation statements)

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“…Common etch gases are the mixing of chlorine, oxygen, and helium. The chlorine-containing gases were used for metal etch for decades and its application for Cr layer etch started in 1980 [5] . The etch reactions were proposed and cited in many publications, but the thermodynamic conditions for these etch reactions were not found.…”

Section: Cr Plasma Etch Reactionsmentioning

confidence: 99%

Thermodynamic study of photomask plasma etching

2004

SPIE Proceedings

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Photomask plasma etch reactions were studied using Gibbs energy minimization method. The equilibrium compositions were analyzed at practical photomask plasma etch conditions of temperatures, pressures, and reactant inputs. The thermodynamic calculations were based on common gaseous systems used in photomask plasma etching such as Cl 2 -O 2 -He, SF 6 -O 2 -He, and CF 4 -O 2 -He, as well as alternative gases. For Cr etch, the thermodynamically calculated results showed that volatile CrO 2 Cl 2 was the moderate equilibrium composition in the predetermined system only when the temperature was higher than 400 o C, indicating that temperatures of heavy particles in practical plasma conditions might be higher than this temperature. The effects of assistant chemicals on equilibrium compositions were investigated. For MoSi etch, the thermodynamic calculation showed that the main volatile etch products were MoF 6 and SiF 4 . The comparison of MoSi etch using SF 6 and CF 4 was made and gaseous input condition for obtaining all volatile products was found, which would be helpful for defectivity and passivation controls. The calculation also showed that the addition of oxygen in SF 6 and CF 4 systems could increase the equilibrium composition of atomic fluorine, resulting in the etch rate increase. This result agreed with previous hypothesis on the oxygen effects on etch rate. For quartz etch, the calculation showed that the main volatile etch product was SiF 4 . For Ta or TaN absorber EUV mask etch, the volatile Tacontaining product was found to be TaCl 5 .

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Section: Cr Plasma Etch Reactionsmentioning

confidence: 99%

Thermodynamic study of photomask plasma etching

2004

SPIE Proceedings

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“…Some of these include: C 2 F 6 , CCl 4 , C 3 F 8 , etc. [1,5,6] Others have proposed gases which use both carbon and hydrogen in order to improve selectivity: CHF 3 , CH 4 , CF 4 -H 2 , etc. [4,6] In this study, sidewall protection is examined as the potential key to CD preservation.…”

Section: Introductionmentioning

confidence: 99%

“…The O 2 and Cl 2 combine with the Cr to form CrO 2 Cl 2 , a volatile product. [1] The non-sidewall-protecting chemistry doesn't adequately protect the CD on the mask from large biases. Typical bias values for the standard He/Cl 2 /O 2 chemistry are in the range of 100 nm with non-uniformities in the range of 20 nm.…”

Section: Introductionmentioning

confidence: 99%

Chrome etch for <0.13 μm advanced reticle production

Buie

Stoehr

Huang

2002

21st Annual BACUS Symposium on Photomask Technology

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The continuous shrinking of design rules results in tighter specifications for advanced chrome dry etch. Specifically, the increasing number of OPC and phase shift layers in mask set for sub 0.13µm technology drives research and development in this area.Chrome layers were traditionally dry etched using a Cl 2 /O 2 /He plasma. While this chemistry has proven to meet the chrome etch requirements in the past its limitations are becoming more and more obvious. In particular, critical dimension control in terms of uniformity and etch bias shows opposing trend lines with the standard chemistry which makes optimization difficult and minimizes the available process space.The Applied Materials Centura® photomask etch chamber has been used along with new gas chemistries to provide improved critical dimension control in chrome for binary photomasks. Oxygen and chlorine are responsible for etching chrome. However, these gases alone do not provide the sidewall protection necessary for the excellent critical dimension control required for advanced mask making for 0.13 µm and below. In this systematic investigation, experiments show a factor of two improvement in etch bias over the standard chemistry (He/O 2 /Cl 2 ). Excellent CD uniformity is also demonstrated.

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“…Patterning of sub-micron-size features in Cr using plasma etching is such a case, for which additional investigations are required. The possible gas mixtures, which are generally used for chromium (Cr) plasma etching, are rather limited, consisting of three possible process schemes: etching in pure Cl 2 or Cl-based gas, etching in Cl 2 (Cl-based gas) + O 2 , and etching in Cl 2 (Cl-based gas) + O 2 + Ar or some other noble gas [1][2][3][4]. In addition to its high reactivity, the advantage of the Cl-based chemistry for Cr etching is associated with the fact that CrO 2 Cl 2 is a volatile etch product with a rather low boiling point compared to other known volatile compounds such as Cr(CO) 6 [4].…”

Section: Introductionmentioning

confidence: 99%