Optical metrology of 3D thin film conformality by LHAR chip assisted method

Utriainen, Mikko; Saastamoinen, Kimmo; Rekola, Heikki; Ylivaara, Oili; Puurunen, Riikka L.; Hyttinen, Pasi

doi:10.1117/12.2609643

Cited by 3 publications

(7 citation statements)

References 7 publications

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“…The PillarHall chip and its cross section are schematically shown in figure 2 [7]. A test structure is created to perform conformality measurements of thin film materials in ALD and CVD processes [8,9]. Once the coating is completed, the upper membrane layer can be removed and the coating quality, i.e.…”

Section: Structure Of the Pillarhall Chipmentioning

confidence: 99%

“…Usually, these kind of studies are performed using traditional crosssectioning of vertical trenches, which can create problems when at an industrial manufacturing scale, since this technique requires a lot of time for analysis and is thus expensive. The PillarHall test chip structure [7][8][9] is a solution that alleviates this problem, since it is technically less demanding and significantly reduces costs.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of PillarHall test chip structures using a reflectometry technique

Danilenko,

Rastgou,

Manoocheri

et al. 2023

Meas. Sci. Technol.

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Thin film samples where one of the thin layers consists of vacuum or air are called PillarHalls due to their support structure in silicon wafers. Custom PillarHall samples were provided by manufacturer and characterized by reflectometry with spectrometer Cary 7000. Data at 8 degrees of angle of incidence were collected with p-polarization of the incident light within the wavelength range of 550-1800 nm. Then these data were analyzed with a dedicated MATLAB code, using fitting software accompanying the transfer matrix method for calculation of the reflectance spectrum. Layer thicknesses and unknown refractive indices were chosen as fitted parameters. The oscillating reflectance spectrum of a PillarHall test chip yielded the air gap thickness of 86 nm with an estimated standard uncertainty of 5 nm. This is close to the nominal value of 100 nm. The results demonstrate that reflectometry data are sensitive to the thickness of a thin air layer deep inside the silicon structure.

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Section: Structure Of the Pillarhall Chipmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of PillarHall test chip structures using a reflectometry technique

Danilenko,

Rastgou,

Manoocheri

et al. 2023

Meas. Sci. Technol.

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“…In some of these studies, the conformality of growth was addressed but only using test structures with an aspect ratio (AR) of 25 at a maximum. 14,17,24 In the present study, we have for the first time used lateral high-aspect-ratio (LHAR) test structures (AR > 10000) with submicron 3D features 30 to investigate how deep and evenly LiPON films could grow in such LHAR structures. In previous works, similar test structures were utilized for other ALD thinfilm materials to quantify the film penetration into the 3D trenches.…”

mentioning

confidence: 99%

“…In the present study, we have for the first time used lateral high-aspect-ratio (LHAR) test structures (AR > 10000) with submicron 3D features to investigate how deep and evenly LiPON films could grow in such LHAR structures. In previous works, similar test structures were utilized for other ALD thin-film materials to quantify the film penetration into the 3D trenches. , Our data are for two different thermal ALD LiPON processes, based on LiO t Bu and Li-HMDS precursors, in combination with DEPA as the source of P, O, and N (Figure ).…”

mentioning

confidence: 99%

“…This was done primarily by using LHAR structures with lateral cavities corresponding to AR values varying from 10000:1 to 2:1 (Figure ). After thin-film deposition, the top-roof poly-Si membrane was peeled off using adhesion tape, thus exposing the deposited film for straightforward conformality analysis . In the study presented here, test structures with two different gap heights ( H = 87 and 420 nm) were used.…”

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Conformal High-Aspect-Ratio Solid Electrolyte Thin Films for Li-Ion Batteries by Atomic Layer Deposition

Madadi,

Heikkinen,

Philip

et al. 2024

ACS Appl. Electron. Mater.

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Lithium phosphorus oxynitride (LiPON) is a stateof-the-art solid electrolyte material for thin-film microbatteries. These applications require conformal thin films on challenging 3D surface structures, and among the advanced thin-film deposition techniques, atomic layer deposition (ALD) is believed to stand out in terms of producing appreciably conformal thin films. Here we quantify the conformality (i.e., the evenness of deposition) of thin ALD-grown LiPON films using lateral high-aspect-ratio test structures. Two different lithium precursors, lithium tert-butoxide (LiO t Bu) and lithium bis(trimethylsilyl)amide (Li-HMDS), were investigated in combination with diethyl phosphoramidate as the source of oxygen, phosphorus, and nitrogen. The results indicate that the film growth proceeded significantly deeper into the 3D cavities for the films grown from LiO t Bu, while the Li-HMDSbased films grew more evenly initially, right after the cavity entrances. These observations can be explained by differences in the precursor diffusion and reactivity. The results open possibilities for the use of LiPON as a solid electrolyte in batteries with highsurface-area electrodes. This could enable faster charging and discharging as well as the use of thin-film technology in fabricating thin-film electrodes of meaningful charge capacity.

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Excellent conformality of atmospheric-pressure plasma-enhanced spatial atomic layer deposition with subsecond plasma exposure times

van de Poll,

Jain,

Hilfiker

et al. 2023

Applied Physics Letters

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Atmospheric-pressure spatial atomic layer deposition (s-ALD) has emerged as a scalable deposition technique combining the advantages of ALD with high deposition rates, suitable for low-cost and high-volume applications. There is a growing interest in atmospheric-pressure plasma-enhanced spatial ALD (PE-s-ALD), e.g., to allow for deposition at reduced temperatures or for materials that are otherwise difficult to prepare by thermal ALD. For low-pressure PE-ALD, conformal films on high aspect ratio features have been achieved despite plasma radical recombination, and the aspects influencing conformality are fairly well understood. This work addresses surface recombination and conformality for atmospheric-pressure PE-s-ALD films. We demonstrate that conformality can be achieved for SiO2 and TiO2 films deposited by atmospheric-pressure PE-s-ALD inside high-aspect-ratio trenches with short plasma exposure times. Using plasma exposure of 0.73 s results in conformal SiO2 and TiO2 films in structures with aspect ratios of 74 and 219, respectively. Additionally, the recombination probabilities of oxygen radicals at atmospheric pressure are extracted to be 4×10−4 for SiO2 and 6×10−5 for TiO2. These results demonstrate that atmospheric-pressure PE-s-ALD can be used for conformal and high-speed depositions on 3D substrates.

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Optical metrology of 3D thin film conformality by LHAR chip assisted method

Cited by 3 publications

References 7 publications

Characterization of PillarHall test chip structures using a reflectometry technique

Characterization of PillarHall test chip structures using a reflectometry technique

Conformal High-Aspect-Ratio Solid Electrolyte Thin Films for Li-Ion Batteries by Atomic Layer Deposition

Excellent conformality of atmospheric-pressure plasma-enhanced spatial atomic layer deposition with subsecond plasma exposure times

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