Method for fabricating high aspect ratio electrodes

A method for building high aspect ratio electrodes in an electrode means (E) comprising parallel electrodes (ε1,ε2) in a dense arrangement, wherein the method comprises successive process steps for:

• a) depositing a first global layer of electrode material (ε) with height h on a substrate (1);
• b) patterning the electrode material (ε) to form first parallel electrodes (ε1) of the electrode means (E), said first electrodes (ε1) having a width w and height h and being separated by a recess (2) of width d, and wherein the method is characterized by comprising successive further process steps for
• c) covering the first electrodes (ε1) with a barrier layer of thickness δ, δ being a fraction of width w, whereby the width d of the recess (2) becomes equal to 2w+2δ;
• d) depositing a second global layer of electrode material (ε) over the first electrodes (ε1) with the barrier layer (3) and filling the recesses (2) therewith;
• e) patterning a second layer of electrode material (ε) to form second parallel electrodes (ε2) of the electrode means (E) in the recesses (2′) between the electrodes (ε1) and the barrier layer (3) covering the latter, said second electrodes (ε1) extending above the first electrodes (ε1) to a height H−h and being insulated therefrom by means of the barrier layer (3), whereafter the sequence of process steps c)-e) are alternatingly applied as required to the first and second electrodes (ε1,ε2) respectively until the desired aspect ratio (n+1)(H−h)/w for all electrodes is obtained in a final process step after performing n sequences of the successive process steps c)-e), a final process step comprising applying electrode material to obtain electrodes (ε1ε2) with approximately equal height (n+1)(H−h) and then removing excess electrode material (ε) in a planarizing process.