Nanostructures wetting evaluation using ultra high frequency ultrasound

Salhab, Abbas; Carlier, Julien; Toubal, Malika; Campistron, Pierre; Neyens, Marc; Nongaillard, Bertrand; Thomy, V.

doi:10.1117/12.2620992

Cited by 1 publication

(3 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The air bubbles ranged in size from very small bubbles to large gaps, creating discontinuities in the photoresist present in the trenches. These trapped bubbles were observed in previous work we conducted on DTI with an aspect ratio of 30 [29]: We showed that a transition to full wetting inside the trenches led to the release of bubbles. In the literature, we find several techniques to remove and control bubbles suspended in fluids, such as degassing the fluid and avoiding pressure drops in the dispense system [30], the addition of surfactants to lower the surface tension [31], or using megahertz acoustic waves to control the bubbles [32].…”

Section: Discussionsupporting

confidence: 74%

“…This indicates the transfer of the acoustic energy to the photoresist layer present inside the trenches. To indirectly quantify the wetting of the photoresist on the DTI, the wet bottom area 'S w ' is calculated, which quantifies the surface area of the wet bottom area [17]. If part of the lower surface of the trenches is covered by photoresist and the rest of the bottom surface is filled by air, the reflection coefficient r 1 is then given as follows:…”

Section: Si Gkr 4602mentioning

confidence: 99%

“…For our part, we have developed an acoustic characterization method based on ultra-high frequency (up to 5 GHz) [16,17] that uses bulk acoustic waves to characterize the wetting efficiency of a liquid droplet deposited on micro-nanopatterned silicon surfaces.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Indirect nanoscale characterization of polymer photoresist wetting using ultra-high frequency acoustic waves

Salhab,

Carlier,

Toubal

et al. 2023

Phys. Scr.

View full text Add to dashboard Cite

The wetting of surfaces with patterns in the order of a hundred nanometers is often a complex phenomenon to analyze and control. In the semiconductor industry, whether it is during the surface cleaning steps or the deposition of the protective mask (photosensitive liquid resin that is then cross-linked), the conformity of the deposit of the liquid layer on the patterned surface must be perfect or else the functionality of the targeted electronic component will be compromised. Thus, understanding the surface wetting of these liquids allows the implementation of optimized processes. In this paper, we present a method of indirect wetting characterization of a photoresist based on ultra-high frequency (# GHz) acoustic waves. This resin is a commercial product called GKR 4602 (belonging to the KrF series of positive photoresists), which is coated in two different ways: either directly onto the surface of a patterned silicon wafer, or after application of a solvent, Propylene Glycol Ethyl Ether (PGEE), which then acts as a pre-wetting layer. The patterned wafer, playing the role of electrical insulation (Deep Trench Isolation, DTI) are 200 nm wide, deep trenches with a high aspect ratio (> 50). The originality of this paper lies in the validation of the acoustic characterization by direct observation of the wetting of the cross-linked resin. To do so, we used a FIB (Focused Ion Beam) microscope which allowed us to make cuts and capture localized images of the wetting state of the photoresist. Moreover, all the results obtained (resins and patterned silicon surfaces) are directly from the microelectronics industry (STMicroelectronics), showing that our method is fully compatible with an industrial approach.

show abstract