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The constant shrinking of critical dimensions in logic manufacturing is driving a change in integration of interconnects. While copper has been the material of choice for the past few decades, it is currently facing a serious challenge from other materials like cobalt. The focus of this paper is three-fold. First, we compare the reactivity of both materials in different media. Next, we confirm that kinetics of native oxide formation when exposed to atmosphere is an order of magnitude slower for copper than for cobalt and that, in the case of cobalt, the presence of an oxide is not avoidable in the industry conditions. And finally, we investigated the compatibility of plating solutions manufactured by aveni for cobalt and copper deposition. Both solutions reveal that, not only do they etch the native oxide of a cobalt seed, but they also preserve the integrity of the underlying metallic cobalt layer. This is highlighted by the fact that no oxide is detected at the interface between the deposited metal and the seed after deposition. We therefore provide evidence of the compatibility of aveni plating solution with a wide array of integrations for next generation interconnects such as copper extension with direct-on-cobalt integration or full cobalt integration.

One of the key parameters to achieve high efficienc y Cu(In,Ga)Se Se2 (CIGS) solar cells is the proper control of Ga grading. From previous results, by using bulk material characterization, a first assessment of the CIGS growth on polyimide foils at low temperature was performed. Moreover, a maximum efficiency of 17.8% ha has been achieved with steep Ga grading. Here, a first step to the establishment of a growth model of CIGS grown at low temperature is proposed by coupling surface and volume characterization. Then, simulation of the photovoltaic performances of the cell is used to complete experimental observations and to explain the benefic ial effect of steep Ga grading.

To improve the efficiencies of Cu(In,Ga)Se 2 solar cells, a perfect knowledge of the absorber composition is an absolute necessity. In order to, we performed, either in-depth or at the surface, a coupling of cross-characterization methods including among others, XPS, SIMS and Nano-Auger. We present here the comparisons of quantitative results determined using each characterization technique, with a specific focus on key composition parameters: GGI (([Ga]/([Ga]+[In])) and CGI ([Cu]/([Ga]+[In])) ratios. With this multi-technique approach, a multiscale determination of those ratios has been obtained, from micrometer to nanometer dimensions

International audience; CIGS based solar cells are still part of the most popular solar cells developed. A chemical study is presented here by using XPS measurements, characterizing the surface chemistry and reactivity, with a focus on deoxidation and further ageing products, among which binary compounds and oxides can be found. Different chemical treatments are also suggested to adjust the surface composition of CIGS materials and to determine the re-oxidation delay. A specific point will be also discussed about the comparative evolution of alkali element distribution during the ageing of conventional CIGS/glass and CIGS/flexible substrate systems, requiring in this case an external alkali source.

Even if silicon solar cells are leader on the worldwide market, research keeps to investigate how to go on increasing the efficiencies. Among the different technologies developed, PERC and n-PERT cells are at present the most promising ones. The fine optimization of those more and more complex structures not only rely on the stack constitution but also on the interfaces properties and quality in-between each layer, and especially the interfaces involving the passivation layers. To this end, XPS profiling is employed in this study to accurately determine the precise chemical composition and local atomic network at those critical interfaces, i.e. between c-Si and the passivation layers, focusing particularly on Al 2 O 3 passivation layer one.

Glow Discharge Optical Emission Spectrometry (GD-OES) is an elemental depth profiling technique, considered as complementary to Auger Spectroscopy, Secondary Ion Mass Spectrometry or X-ray Photoelectron Spectroscopy for the characterization of thin films. GD-OES has already been widely used for the characterization of materials used for photovoltaic applications and results obtained for CIGS and Perovskites based technologies will be presented. With its most recent development, allowing for the direct measurement of layer thicknesses, GD-OES has become even more attractive for materials characterization. This innovative feature called Differential Interferometry Profiling (DiP) will be described and illustrated by examples on CIGS solar cells.

Photovoltaic cells based on chalcogenides CIGS (Cu(In, Ga)Se 2 ) thin films are a very promising technology. To improve cells performances, a fine optimization of the CIGS absorber properties is needed. Hence, we developed a cross strategy method combining the surface, volume and specific interfaces of the final device characterizations. These features deal with a large panel of physico-chemical techniques for the chemical composition (XPS, EDS, ICP-OES, GD-OES, AES), the morphology (SEM, AFM) and the optical parameters (spectroscopic ellipsometry) determination. This article demonstrates the crucial interest of this cross strategy on CIGS absorbers and focus on the accuracy and complementarities of each technique.

A new bath composition for ZnS buffer layer deposition is presented allowing its photochemical growth on CIGSe absorbers. The main advantages of this solution compared to classical CBD-Zn(S, O) bath are: the deposition occurs at room temperature, the concentration of chemical precursors is 10 times lower than classical CBD-Zn(S, O), the use of a complexing agent such as ammonia is avoided and the same bath can be reused for several depositions. The same bath can be re-used for at least 4 times, leading to efficiencies between 13 and 14%, which is similar to what is obtained with CdS-buffered references.

CBD-Zn(S,O,OH) remains one the most studied and promising Cd-free buffer layer for Cu(In,Ga)Se2-based solar cells, and has already demonstrated its potential to lead to high-efficiency solar cells. However Zn(S,O,OH) deposition time and metastable behavior of the final devices remain critical to outperform CdS-based devices. The aim of this work is to study and understand the influence of additives such as H2O2 on the deposition bath and on the surface of the absorber. These results will be related with final performances of the devices. A new promising additive, persulfate S2O82−, will be presented and could be the key to go beyond CdS-based solar cell records.

Zn(S, O, OH) represents the most studied Cd-free material for replacing chemical bath deposited (CBD)-CdS buffer layers in Cu(In, Ga)Se2-based solar cells. However, the record performances remain lower than the CdS. The aim of this work is to study new bath compositions for CBD-Zn(S, O, OH), by introducing new complexing and non-complexing reactants for higher efficiencies, and to analyze their effects on growth mechanisms. Promising bath compositions based on the combined used of H2O2 and tri-sodium citrate have been developed, and could be a new avenue to outperform the CdS-based solar cells.

Within the UltraCIS project we have started to explore the possibility of reducing down the thickness of the Cu(In, Ga)Se 2 (CIGSe) layer to the sub-micron level (0.1μm) while maintaining a high efficiency level of solar cells. The three main approaches we used are: — Reducing the CIGSe thickness by chemical etching combining the thickness reduction and smoothing effect of the absorber. Efficiency higher than 10 % on small area cells with an absorber thickness of 0.5 μm are obtained. Losses were attributed exclusively to the reduced photocurrent and the loss on texturation of the absorber — Optical management by front contact texturation or by replacement of the back contact by the “lift-off” of CIGSe layer from the Mo layer and deposition of a new reflective back contact. — Application of plasmonic structures to CIGSe solar cells enabling light confinement at the subwavelength scale

In this paper, we present an evaluation of electrografted seed layers as an alternative metallization route to usual PVD liners for deep Through Silicon Vias (TSV). The capability of the electrografted layers to provide a better step coverage is demonstrated in high aspect ratio structures. The positive impact of the seed layer quality on the subsequent filling steps by conventional copper electrodeposition is also presented.

This paper presents a thermodynamic study of Chemical Bath Deposition (CBD) of zinc sulfide based films in aqueous solution. The aim is a better understanding of the effect of temperature and pH on the deposition mechanism and film composition. The formation of solid phases has been predicted by means of the precipitation conditions of ZnO, Zn(OH)2 and ZnS as a function of temperature between 298 and 363 K. Films have been deposited, without ammonia, on the basis of calculated diagrams and first results on solar cells based on electrodeposited CuIn(S,Se)2 layers have been demonstrated.