Through-mask plating

There is a basic difference between the damascene and the plating-through-mask processes in the way in which the trenches and vias are filled with electrochemically deposited Cu, either through electro- or electroless technique. In multilevel metal structures, vias provide... 

Preferred growth from the bottom may be achieved by the addition of suitable additives. In the plating through mask process only the bottom is active wliile the sidewalls are inactive, resulting in the grow of Cu deposit from the bottom, as depicted in Fig. 

Fig. 3. Schematic illustration of the distinction between superficial current density igup and active current density in the case of through-mask plating. The enlarged view in the drde illustrates the crowding of the lines of current on the feature scale. The larger picture illustrates how, on the pattern scale, the lines of current bend in response to an uneven distribution of resist (black dots) on the electrode surface. (Reprinted by permission of the publisher. The Electrochemical Society, Inc. [25]).

L. T. Romankiw, A Review of Plating Through Polymeric Resist Masks, Extended Abstracts of the Electrochemical Society, 79-2, No. Abstract No. 462, 1165-1166, The Electrochemical Society Inc., Pennington, NJ (1979). 

Figure 2.4 Voltammetry demonstrating that a self-assembled Cn6-alkane thiol film effectively blocks nickel electrodeposition on a copper substrate. The inset shows that patterning methods, such as soft lithography, may be used to produce three-dimensional topographies by through-mask plating using an alkanethiol layer as a resist [96],...

Fig. 13.1 Ink-jet nozzle plate fabricated by through-mask electrochemical micromachining, Schematic of the concept top), and a photograph showing an array of nozzles bottom) [23]...

Abstract. Many different patterns have been proposed for coded masks, from Fresnel zone plates, through scatter-hole designs, to various patterns which are optimal in different senses. We present a compendium of such patterns, with examples and their autocorrelation functions, together with a bibliography of associated literature. 

Plated-through via holes used only for interfacial connection do not need to be filled with solder. To prevent solder fill, manufacturers usually place temporary or permanent masks over the vias during the soldering process. PTHs or vias without leads when exposed to solder should meet the following acceptability requirements ... 

In this technique, the micro structure is either directly or through masks incorporated into a suitable material, which is usually located on a carrier plate using UV lithography, lithography with synchronic radiation, or X-ray lithography. The machined interspaces are then filled with metal by an electroplating process. The actual mold inserts are then manufactured from these metal parts. 

The applicability of through-mask plating technology is limited by the requirement that the masking material mnst be compatible with the electrolyte nsed for plating. Conventional photoresist materials typically restrict the use of through-mask plating to acidic or weakly alkaline... 

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