Enhanced microfabrication using electrochemical techniques

A method for subtractively processing a layer of etchable material formed over an electrically conductive surface region of a workpiece, comprising:

• connecting the workpiece in an electrochemical circuit that includes a control electrode, a reference electrode, and the electrically conductive surface region of the workpiece;
• immersing at least a portion of the workpiece in a liquid solution that comprises an etchant for the etchable material, so that etching of the etchable material is initiated;
• dynamically monitoring the etching of the etchable material at each of a plurality of intervals between the initiation of the etching and an endpoint of the etching, wherein the dynamic monitoring comprises measuring an electrical signal in the electrochemical circuit;
• performing a plurality of rinse cycles, wherein the etching is interrupted, and the workpiece is rinsed during each of the rinse cycles;
• measuring the electrical signal in the electrochemical circuit during each rinse cycle for dynamic monitoring of the etching, measurement of the electrical signal for dynamic monitoring being performed during the rinsing but not during the etching;
• and
• terminating the etching when the electrochemical signal satisfies a criterion indicating that the endpoint has been reached.