Low temperature etch chuck: Modeling and experimental results of heat transfer and wafer temperature

Wright, Dylan; Hartman, Dennis C.; Sridharan, U. C.; Kent, M.; Jasiński, Tadeusz; Kang, Sangsoo

doi:10.1116/1.578203

Cited by 36 publications

(13 citation statements)

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“…The other part emerges from the etch reaction heat and is ruled by the silicon loading times the etch rate (this etch rate depends on Mogab's equation of loading and on the square root of time for a high aspect ratio as has been found before). Also, a heat flux due to convection, radiation and/or Eddy currents exists, but these fluxes are calculated to be minor for the high rate conditions considered in this study [339]. Finally, there is no indication that photon heating caused by the plasma glow is relevant, but this effect might become important when strongly absorbing resist layers are used.…”

Section: Heat Management-silicon Loading and Mask Conductivitymentioning

confidence: 83%

“…In the free-molecular state, the individual molecules carry the heat from wall to wall and the molecular heat transfer coefficient is expressed as α free = 0.125β eff (f + 1)v av p/T. With f being the degrees of freedom and β eff = β/(2 − β) ≈ 0.5 being the effective accommodation coefficient, β eff accounts for the incomplete energy exchange (momentum transfer) between the gap's fixed wall molecules (Si, Al, O, H, He) and impinging molecules (He) [339,340]. The velocity v av = √ [8RT/πM] depends on the square root of temperature over molar mass M. So, the molecular heat transfer is independent of the gap distance, since it does not affect the particle flux nor the energy transport per molecule.…”

Section: Effect Of Helium Backside Pressure On Temperaturementioning

confidence: 99%

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Black silicon method: X. A review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

Jansen¹,

Boer²,

Unnikrishnan³

et al. 2009

J. Micromech. Microeng.

262

227

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An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O 2) or a fluorocarbon (FC) gas (C 4 F 8 or CHF 3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication of directional profiles, pulsed-mode DRIE is far easier to handle, is more robust with respect to the pattern layout and has the potential of achieving much higher mask etch selectivity, whereas in a mixed-mode the etch rate is higher and sidewall scalloping is prohibited. It is found that both pulsed-mode CHF 3 and C 4 F 8 are perfectly suited to perform high speed directional etching, although they have the drawback of leaving the FC residue at the sidewalls of etched structures. They show an identical result when the flow of CHF 3 is roughly 30 times the flow of C 4 F 8 , and the amount of gas needed for a comparable result decreases rapidly while lowering the temperature from room down to cryogenic (and increasing the etch rate). Moreover, lowering the temperature lowers the mask erosion rate substantially (and so the mask selectivity improves). The pulsed-mode O 2 is FC-free but shows only tolerable anisotropic results at −120 • C. The downside of needing liquid nitrogen to perform cryogenic etching can be improved by using a new approach in which both the pulsed and mixed modes are combined into the so-called puffed mode. Alternatively, the use of tetra-ethyl-ortho-silicate (TEOS) as a silicon oxide precursor is

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Section: Heat Management-silicon Loading and Mask Conductivitymentioning

confidence: 83%

Section: Effect Of Helium Backside Pressure On Temperaturementioning

confidence: 99%

Black silicon method: X. A review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

Jansen¹,

Boer²,

Unnikrishnan³

et al. 2009

J. Micromech. Microeng.

262

227

View full text Add to dashboard Cite

show abstract

“…[1][2][3] Recently however, the research on thermal issues has spread to the reticle side of the manufacturing process. [4][5][6][7][8] One concern is that particles may become lodged between the chuck and reticle, inducing distortions once the reticle is chucked flat. With the advent and proliferation of the electrostatic chuck, backside particle contamination will have to be addressed by the lithographic community.…”

Section: Introductionmentioning

confidence: 99%

“…2,3 Thermomechanical analyses of electrostatic-chucked wafers have been previously investigated. [1][2][3][4] In this paper, the thermomechanical response of an EUV reticle during exposure has been determined, and preliminary design curves will be presented.…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical modeling of the pin-chucked EUV reticle during exposure

Wei

Martin

Beckman

et al. 2002

Emerging Lithographic Technologies VI

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Extreme ultraviolet (EUV) lithography has emerged as the forerunner in the selection process to become the industry's choice as the technology for next-generation lithography (NGL). An advantageous characteristic of the EUV reticle is that it is reflective, so it can be chucked across the entirety of its backside. This chucking will aid in meeting flatness requirements as well enhancing the heat removal ability of the chuck when compared to the mounts used for optical reticles. The EUV exposure process occurs in a vacuum environment, which precludes the use of vacuum chucks; therefore, electrostatic chucks are the favored choice. One concern is that particles may become lodged between the chuck and reticle, causing distortions to occur once the reticle is chucked flat. To counter this effect, electrostatic pin chucks have been proposed. However, because of the lower heat transfer ability of the pin chuck due to the interstitial gap, thermal issues may arise. A predominant pin-chuck configuration has yet to emerge, and there is no set of standards to facilitate new designs. The intent of this paper is to provide general guidelines to assist in preliminary designs. Parameters that were seen as potentially important factors in pin chuck performance were chosen and the results are presented.

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“…Wachman (19621, Devienne (19651, Springer (1970, andJoshi (1981). The subject has received continuous attention, because of its importance in basic fundamental understanding of heat-transfer mechanisms involving monatomic and polyatomic gases, and because of its significant application in thermal insulation in relation to solar receivers (O'Shea and Collins, 1992), low thermal conductance in evacuated windows (Collins and Robinson, 1991), cooling workpiece in vacuum materials processing equipment (Sieradzki, 1985;Wright et al, 1992). The last application has necessitated the undertaking of the work reported here from design considerations for the conditions actually employed in manufacturing industries (Baldwin, 1993).…”

Section: Introductionmentioning

confidence: 99%

Heat transfer through a low-pressure gas enclosure as a thermal insulator: Design considerations

Demi̇rel

Saxena

1996

Int. J. Energy Res.

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SUMMARYHeat transfer through gases at low pressures, rarefied media, plays a very significant role in the design of solar receivers and low-temperature cooling equipment. It is shown here that low-pressure and transition regimes of heat transfer prevail in such applications. State-of-the-art procedures for estimating these heat-transfer rates are presented together with an improved expression for the thermal accommodation coefficient for monatomic gases on engineering surfaces. The latter are characterized with values of thermal accommodation and reflection coefficients. Numerical calculations relevant to design engineers interested in these industrial applications are presented and the same are discussed for the dependencies of the heat-transfer rates on different design and operating parameters. It is shown that the values of surface reflectivity coefficient have a pronounced contribution in low density heat-transfer calculations at low gas temperatures, and are negligibly small for the temperatures greater than 900 K.

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Low temperature etch chuck: Modeling and experimental results of heat transfer and wafer temperature

Abstract: Process kit and wafer temperature effects on dielectric etch rate and uniformity of electrostatic chuck Low voltage and high speed operating electrostatic wafer chuck

Cited by 36 publications

References 0 publications

Black silicon method: X. A review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

Black silicon method: X. A review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment

Thermomechanical modeling of the pin-chucked EUV reticle during exposure

Heat transfer through a low-pressure gas enclosure as a thermal insulator: Design considerations

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