Simplified method of making vias for merged MR head

A method of making a thin film magnetic head comprising the steps of:

• forming a plurality of etchable thin film layers, which can be etched by an etchant, on top of a plurality of non-etchable thin film layers which cannot be etched by said etchant;
• forming a photoresist layer on top of the etchable thin film layers;
• forming at least first and second openings in the photoresist layer for forming first and second vias which extend through said etchable thin film layers to first and second of said non-etchable thin film layers, the first via extending through at least one of the etchable thin film layers and the second via extending through at least one more etchable thin film layer than the first via;
• and
• each of the first and second holes having a lateral dimension, the lateral dimension of the first opening having a downsizing factor applied so that lateral etching of said at least one of the etchable thin film layers etches a desired laterally sized first via from a time when said etchant in the first opening first reaches said first one of the non-etchable thin film layers to a time when said etchant in the second opening first reaches said second non-etchable thin film layer.

A method of making a thin film structure comprising the steps of:

• forming first and second electrically conductive layers between first and second non-magnetic layers and forming the first and second non-magnetic layers between first and second magnetic layers;
• forming a third non-magnetic layer on top of the second magnetic layer;
• forming a photoresist layer with at least first, second and third openings on top of the third non-magnetic layer for making first, second and third vias, each of the second and third vias being through the third and second non-magnetic layers to the first and second electrically conductive layers and the first via being through the third non-magnetic layer to the second magnetic layer;
• simultaneously introducing an etchant into the first, second and third openings to etch through the third and second non-magnetic layers to the first and second electrically conductive layers and to the second magnetic layer, the etchant in the first opening reaching the second magnetic layer before the etchant in the second and third openings reaches the first and second electrically conductive layers;
• and
• downsizing a lateral dimension of the first opening with respect to lateral dimensions of the second and third openings so that the etchant in the first opening will etch the first via with a desired lateral configuration upon the occurrence of the etchant in the second and third openings first reaching the first and second electrically conductive layers.

A method of making at least first and second vias in etchable layers down to non-etchable layers, the first via being deeper than the second via comprising the unordered steps of:

• forming a single photoresist layer on top of the etchable layer;
• forming first and second openings in the single photoresist layer above first and second locations for said first and second vias;
• applying an etchant in the first and second openings which etches through the etchable layers to the non-etchable layers, the etchant in the first opening first reaching a first non-etchable layer before the etchant in the second opening reaches a second non-etchable layer;
• the first opening being downsized relative to the second opening to account for the etchant in the first opening reaching the first non-etchable layer before the etchant in the second opening reaches the second non-etchable layer.

A method employing a wet etchant for forming at least first and second holes in etchable material overlaying non-etchable material, the etchable material being etchable by the wet etchant and the non-etchable material being non-etchable by the wet etchant, the first and second holes having widths W1 and W2 and depths d1 and d2 respectively, the depth d1 being less than the depth d2, and the wet etchant being capable of etching downwardly to form said depths while etching laterally to form said widths, the method comprising the steps of:

• forming a photoresist layer on the etchable layer having first and second openings with first and second widths W' 1 and W' 2 respectively;
• placing said wet etchant simultaneously in said first and second openings so that the wet etchant etches said etchable material downwardly and laterally to said non-etchable material in time t1 to form a partially completed hole with the depth d1 but a width less than W1 and etches said etchable material downwardly and laterally to said non-etchable material in time t2 to form said second hole with width W2 and depth d, the time t1 being less than time t2;
• and
• in the step of forming the photoresist layer, downsizing the width W' 1 in the first opening in the photoresist layer so that during a time duration t2-t1 the partially completed hole is etched laterally an additional amount to provide said first hole with width W1.

A method employing a wet etchant for forming at least first and second circular holes that extend downwardly in etchable layers to non-etchable layers, wherein a first etchable layer overlays a first non-etchable layer and the first and second etchable layers overlay a second non-etchable layer, the etchable layers being etchable by the wet etchant and the non-etchable layers being non-etchable by the wet etchant, the first and second holes having diameters D1 and D2 and depths d1 and d2 respectively, the depth d1 being less than the depth d2, the method comprising the steps of:

• forming a photoresist layer on the first etchable layer with first and second circular openings having first and second diameters D' 1 and D' 2 respectively;
• placing said wet etchant in said first and second openings so that the wet etchant etches downwardly and laterally through said first etchable layer to said first non-etchable layer in time t1 to form a partially completed hole with a diameter less than D1 and etches downwardly and laterally through said first and second etchable layers to said second non-etchable layer in time t2 to form said second hole with said diameter D2, the time t1 being less than the time t2;
• and
• in the step of forming the photoresist layer, the diameter D' 1 in the first opening of the photoresist layer having a downsizing factor applied so that during a time duration t2-t1 the partially completed hole is etched laterally to provide said first hole with diameter D2.