Built-in resistance sensor for measuring slider level pole width at point “A” (PWA) for PMR/MAMR writers

A specially configured non-functional PMR (perpendicular magnetic recording) or MAMR (microwave assisted magnetic recording) writer for measuring main pole (MP) widths during a lapping process, comprising:

• a MP having a trapezoidal cross-section in an air-bearing surface (ABS) plane, a write-gap (WG) formed on a trailing edge surface of said MP and extending laterally and symmetrically beyond said trailing edge surface, a write shield (WS) above said (WG), side gaps (SG) filled with an insulating material and disposed against and contacting both lateral sides of said MP, and leading shields (LS) disposed on either side of said SG, wherein said special configuration comprises:
• a (built-in sensor) comprising the MP, WS, the WG that is filled with a conductive material or a microwave generator stack, and a resistance measuring circuit to measure a resistance, R, between said MP and said WS that is comprised of a resistance measurement device connected with a lead to the MP and with a lead to the WS;
• whereby
• a measurement of said resistance, R, during a lapping process on said PMR or MAMR writer, and SH (a step height of the WG) that is measured using an adjacent Writer Resistive Lapping Guide (WRLG) sensor are used to determine a width of a trailing edge, PWA, of said MP in said ABS.

A perpendicular magnetic recording (PMR) writer or microwave assisted magnetic recording (MAMR) writer, comprising:

• a magnetic main pole (MP) emerging at an air-bearing surface (ABS), said MP having a trapezoidal ABS face that is wider at a cross-track trailing edge surface, denoted “A”, said width at “A” being denoted PWA, than at a parallel leading edge surface and wherein said trailing and leading edge surfaces are connected by symmetrically formed side edge surfaces;
• a write gap layer (WG) formed over said “A” surface and extending symmetrically beyond lateral edges of said “A” surface and having a back edge at a SH from the ABS;
• wherein
• said WG is a conductive material in the PMR writer or a microwave generating stack in said MAMR writer;
• side gap layers formed against side edge surfaces, said side gap layers abutting undersides of said write gap layer;
• and a write shield (WS) on the WG;
• wherein the value of PWA has been accurately estimated with a built-in electrical resistive sensor measurement using a first resistance measurement device connected with a lead to the MP and a lead to the WS to determine a resistance R in the built-in sensor comprised of the WG, WS and MP;
• and with an adjacent writer resistance lapping guide (WRLG) sensor configured to produce a second resistance measurement that is calibrated to the WG SH.