Mask damage by electrostatic discharge: a reticle printability evaluation

Rudack, Andrew C.; Levit, L. B.; Williams, Alvina M.

doi:10.1117/12.474516

Cited by 5 publications

(3 citation statements)

References 3 publications

(4 reference statements)

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“…The location coordinates for the damage site is subsequently used to position an Atomic Force Microscope for a higher resolution scan of an individual defect as shown in Figure 5. Numerous instances of damage are observed to be similar to Canary™ reticles seeing E-field exposures [4]. A naming convention had been established for damage observed on Canary™ reticles: chrome foam, chrome lava, chrome crater.…”

Section: Methodsmentioning

confidence: 98%

Induced ESD damage on photomasks: a reticle evaluation

Rudack¹,

Pendley²,

Gagnon

et al. 2003

SPIE Proceedings

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An Electric-field (E-field) exposure tool for Photomasks was designed, assembled, then utilized to subject 250 nanometer technology node reticles to variable electric fields. A similar study had been demonstrated using the Canary™ Reticle [1]. The goal was to induce an Electrostatic Discharge (ESD), and attempt to damage the reticle's chrome structures via the Field Induced Damage Model. Electrostatic Discharge emits a radio wave in the 100 MHz to 2.0 GHz frequency range, which can be detected using a Digital Sampling Oscilloscope and antenna [2]. Once detected via radio wave sampling techniques, the Field Induced Damage is evaluated on a KLA STARlight™ inspection tool, and a damage map provided. A Digital Instruments Atomic Force Microscope utilizes the damage map to locate defects for further evaluation.

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Section: Methodsmentioning

confidence: 98%

Induced ESD damage on photomasks: a reticle evaluation

Rudack¹,

Pendley²,

Gagnon

et al. 2003

SPIE Proceedings

Self Cite

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“…Another reason for failing to identify EFM is that an affected reticle would probably start to print defective wafers long before the degradation had reached such an advanced stage of development, as shown in the paper by Rudack et al 15 Hence, the reticle would probably be sent for cleaning in the hope that this would rectify the problem. This characteristic has been confirmed in a semiconductor production fab, where yield loss was suffered despite the regular reticle inspections in the fab having detected no significant reticle defects.…”

Section: How Electric Field Damages a Reticlementioning

confidence: 99%

Current understanding of the electrostatic risk to reticles used in microelectronics and similar manufacturing processes

Rider

2018

J. Micro/Nanolith. MEMS MOEMS

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Abstract. This paper explains how an electric field and a reticle interact and describes the different kinds of damage that can be caused to a reticle through its exposure to electric field. It is shown why electrostatic reticle damage has changed from ESD damage (which causes yield to suddenly drop precipitously) into a gradual and cumulative form of degradation that is very difficult to diagnose. It is explained why some of the approaches that have been taken to reduce ESD damage in the semiconductor factory, such as equipotential bonding and the use of static dissipative plastics for making reticle pods, actually increase the risk of this cumulative type of electrostatic degradation in reticles. When assessing the risk to reticles and designing an effective protective strategy for reticle handling, it is shown why one must take into account the temporal characteristics of a reticle's interaction with electric field-including the effect that the reticle's immediate surroundings will have on that interaction-as well as considering the strength of any electric field in the reticle handling environment. Solutions are presented that would allow the electrostatic risk to reticles to be reduced significantly, without requiring major changes to operating procedures in semiconductor manufacturing facilities.

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“…A test reticle damaged by EFM to an extent similar to fig. 7a was tested by Rudack, Levit and Williams using an aerial image metrology system and the defect was shown to produce complete line bridging in the aerial image 13 . This is due to the Mask Error Enhancement Factor (MEEF) in advanced lithography, which causes amplification of any CD error that is present in the reticle.…”

Section: Relevance To Production Reticlesmentioning

confidence: 99%

Experimental quantification of reticle electrostatic damage below the threshold for ESD

Rider¹,

Kalkur

2008

SPIE Proceedings

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The damage mechanisms that take place when a reticle is subjected to electrical stress by exposure to an electric field have been investigated by applying voltage directly to the structures in a special test reticle. Surface current was recorded at all levels of stress from 1V to 100V. The current/voltage characteristic was polarity dependent and exhibited increasing non-linearity as the feature spacing was reduced. Atomic Force Microscopy showed that the electrical stress caused EFM (Electric Field induced Migration of chrome), matching the damage seen in reticles stressed through induction by an external electric field. No ESD events were recorded, confirming that EFM is independent of ESD and that it occurs with lower electrical stress. The threshold for EFM was found to be five times lower than the previous estimate, starting at 1V with 1µm spacing. Damage caused by EFM was shown to be continuous, cumulative and the rate of CD degradation was measured to be from 3 to 6 nm per second.

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Mask damage by electrostatic discharge: a reticle printability evaluation

Cited by 5 publications

References 3 publications

Induced ESD damage on photomasks: a reticle evaluation

Induced ESD damage on photomasks: a reticle evaluation

Current understanding of the electrostatic risk to reticles used in microelectronics and similar manufacturing processes

Experimental quantification of reticle electrostatic damage below the threshold for ESD

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