Levitech BV

Almere Stad, Netherlands

Levitech BV

Almere Stad, Netherlands

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Poodt P.,TNO | Cameron D.C.,Lappeenranta University of Technology | Dickey E.,Lotus Applied Technology | George S.M.,University of Colorado at Boulder | And 6 more authors.
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2012

Atomic layer deposition (ALD) is a technique capable of producing ultrathin conformal films with atomic level control over thickness. A major drawback of ALD is its low deposition rate, making ALD less attractive for applications that require high throughput processing. An approach to overcome this drawback is spatial ALD, i.e., an ALD mode where the half-reactions are separated spatially instead of through the use of purge steps. This allows for high deposition rate and high throughput ALD without compromising the typical ALD assets. This paper gives a perspective of past and current developments in spatial ALD. The technology is discussed and the main players are identified. Furthermore, this overview highlights current as well as new applications for spatial ALD, with a focus on photovoltaics and flexible electronics. © 2012 American Vacuum Society.


Hennen L.,Levitech BV | Hennen L.,TU Eindhoven | Granneman E.H.A.,Levitech BV | Kessels W.M.M.,TU Eindhoven
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2012

Aluminum oxide (Al2O3) thin films yield excellent surface passivation of silicon solar cells. However, unwanted delamination, known as blisters, can occur upon annealing. In this research, blistering is linked to hydrogen diffusion in the bulk. Results reveal competition between diffusion lateral and perpendicular to the interface. Therefore, large blister densities coincide with small blister diameters and vice versa. The total blister volume, however, is independent of blister size distribution, but linked to hydrogen diffusion from the Al2O3 bulk. The blister volume was determined using AFM measurements, which show identical blister shapes for different blister sizes. Additionally, no direct relationship between blister formation and minority carrier was found. © 2012 IEEE.


Granneman E.H.A.,Levitech BV | Kuznetsov V.I.,Levitech BV | Vermont P.,Levitech BV
ECS Transactions | Year: 2014

Al2O3 is the first ALD film material being introduced in the solar cell (PV) industry. The primary driver for implementation is twofold: excellent surface passivation and low cost-of-ownership. 'Spatial' ALD systems satisfy both criteria. On FZ and Cz-type wafers minority carrier lifetimes in the range of 5-8 and 0.5-1 ms, respectively, are obtained. With this type of film, PERC-type cells with efficiencies > 20 % were realized. Furthermore, such cells are processed with throughput numbers > 3000 wafers/hr. The thermal stability of the film is improved by selecting thin films (< 6 nm), and by carrying out a post-deposition anneal at 600 °C. This anneal drives out excess hydrogen that is incorporated during deposition, thereby avoiding the formation of blisters upon exposure to subsequent high-temperature ('firing') steps. © 2014 by The Electrochemical Society.


Cesar I.,Energy Research Center of the Netherlands | Mewe A.A.,Energy Research Center of the Netherlands | Granneman E.,Levitech BV | Vermont P.,Levitech BV | Weeber A.W.,Energy Research Center of the Netherlands
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2012

Silicon solar cells that dominate today's market are H-pattern cells based on p-type silicon wafer material with a full Al Back Surface Field (BSF) as rear contact. ECN's rear passivated bi-facial PASHA (Passivated on all sides H- pattern) and ASPIRe (All Sides Passivated and Interconnected at the Rear, MWT) concepts answer the market pressure to decrease the euro/watt price and increase the efficiency. For optimized cells we estimate 0.5-0.8% absolute higher cell efficiencies compared to the industrial standard due to better rear passivation and reflection, while thinner wafers <150um) can be processed with limited yield loss. In addition, Al paste consumption can be reduced by 50-70% owing to the open rear metallization. Here we report on the improved performance of PASHA cells passivated by an uncapped Al2O3 layer on the rear, through which Al paste is fired for contact and local aluminum BSF formation. The Al2O3 dielectric layer is deposited in the Levitrack, an industrial-type system for high-throughput Atomic Layer Deposition (ALD) developed by Levitech. On Cz and mc material, a gain in JscxV oc of 1% and 2.5% respectively is obtained compared to the reference, at a rear metal fraction of 30%. Localized IQE mapping shows that the passivation quality of the Al2O3 passivation layer is maintained after firing which is a major improvement as compared to our previous report. Furthermore, reliability tests on single cell laminates (Cz cells) suggest that the passivation layer remains stable during the lifetime of a module. © 2012 IEEE.


Kuznetsov V.I.,Levitech BV | Granneman E.H.A.,Levitech BV | Vermont P.,Levitech BV | Vanormelingen K.,Levitech BV
ECS Transactions | Year: 2010

A high-throughput ALD system based on wafer transport in an atmospheric gas bearing was developed. Line-shaped TMA and H 2O precursor zones are present in the direction perpendicular to transport takes place. Thin Al 2O 3 films of 4-24 nm were deposited at wafer speed of 160-230 mm/s (corresponding to a throughput of 2400-3600 wph). After annealing and firing the films show good passivation. Effective minority carrier lifetimes measured on 2.3 Ω cm p-type c-Si wafers at excess carrier density of 1E15 cm -3 reach values of 0.3-2.5 ms depending on surface preparation, annealing steps and film thickness. No degradation of films during firing was observed and the lifetime values remain stable in time. The Levitrack system presented in this paper is expected to meet the requirements of the PV industry. ©The Electrochemical Society.


Kuznetsov V.I.,Levitech B.V. | Ernst M.A.,Levitech B.V. | Granneman E.H.A.,Levitech B.V.
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014 | Year: 2014

Surface passivation is of vital importance for next generation solar cells. Outstanding properties of atomic layer deposition (ALD) can be employed to passivate Si surface with very good uniformity over large areas, excellent step coverage on non-planar surfaces and precise thickness control of nano-thick layers. The challenge is to apply ALD in a cost effective way acceptable for PV industry. In this work we report on the development of atmospheric pressure spatial ALD for (inline) deposition of Al2O3 layers with a throughput of 2000-3600 wafers/hour and low TMA precursor consumption. Layers with a thickness of 6-10 nm are optimal for rear side passivation, resulting in effective chemical and field-effect passivation without delamination (blistering) at the contact annealing step. This passivation is implemented in mass production and gives an efficiency improvement of 0.4-0.8% for PERC type solar cells. © 2014 IEEE.


Cesar I.,Energy Research Center of the Netherlands | Manshanden P.,Energy Research Center of the Netherlands | Janssen G.,Energy Research Center of the Netherlands | Granneman E.,Levitech BV | And 2 more authors.
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2013

The p-type bi-facial cell concept, p-PASHA (Passivated on all sides H-pattern), is developed at ECN and employs an uncapped Al2O 3 passivation layer on the rear through which a screen printed H-pattern of aluminium contacts is fired. Here we report a net gain in cell efficiency of 0.2% absolute for the p-PASHA cell vs. industrial reference with the addition of a clean and an ALD step. Even higher gains up to 0.5% abs. are expected after optimization of the cell design and process. Apart from the efficiency gain, the bi-facial cell concept allows for 50-80% reduction in Al paste consumption, the use of thinner wafers, and consists of less processing steps compared to prevalent PERC concepts. The Al2O3 dielectric layer is deposited in the Levitrack, an industrial-type system for high-throughput Atomic Layer Deposition (ALD) developed by Levitech. The efficiency gain is obtained on multi-crystalline wafers, at a rear metal fraction of 40%. Localized IQE mapping, cross-sectional SEM investigation, resistance measurements and 2D simulation relate the efficiency improvement compared to our conventional process to better eutectic and BSF formation at the Al contact edges. © 2013 IEEE.


Disclosed is a process tunnel (102) through which substrates (140) may be transported in a floating condition between two gas bearings (124, 134). To monitor the transport of the substrates through the process tunnel, the upper and lower walls (120, 130) of the tunnel are fitted with at least one substrate detection sensor (S1, . . . , S6) at a respective substrate detection sensor location, said substrate detection sensor being configured to generate a reference signal reflecting a presence of a substrate between said first and second walls near and/or at said substrate detection sensor location. Also provided is a monitoring and control unit (160) that is operably connected to the at least one substrate detection sensor (S1, . . . , S6), and that is configured to record said reference signal as a function of time and to process said reference signal.


Patent
Levitech B.V. | Date: 2011-01-31

A method, comprising: providing a process space atmosphere at a process space atmosphere pressure; providing an exterior atmosphere at an exterior atmosphere pressure that is different from the process space atmosphere pressure; providing a passage via which the exterior atmosphere is in open communication with the process space atmosphere, and via which substrates are exchangeable between the exterior atmosphere and the process space atmosphere; injecting an exchange fluid into the passage at at least one exchange fluid injection point, so as to effect a flow of exchange fluid that extends through at least a part of the passage, wherein said flow is directed towardsthe exterior in case the exterior atmosphere pressure is greater than the process space atmosphere pressure; orthe process space in case the exterior atmosphere pressure is smaller than the process space atmosphere pressure.


Patent
Levitech B.V. | Date: 2010-11-19

An apparatus (100) comprising:a process tunnel (102) including a lower tunnel wall (120), an upper tunnel wall (130), and two lateral tunnel walls (108), wherein said tunnel walls together bound a process tunnel space (104) that extends in a transport direction (T);a plurality of gas injection channels (122, 132), provided in both the lower and the upper tunnel wall, wherein the gas injection channels in the lower tunnel wall are configured to provide a lower gas bearing (124), while the gas injection channels in the upper tunnel wall are configured to provide an upper gas bearing (134), said gas bearings being configured to floatingly support and accommodate said substrate there between; anda plurality of gas exhaust channels (110), provided in both said lateral tunnel walls (108), wherein the gas exhaust channels in each lateral tunnel wall are spaced apart in the transport direction.

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