Polyimide layer depressions between metal pillars

A semiconductor package, comprising:

• a semiconductor die including circuitry;
• a first metal pillar coupled to the circuitry and extending away from the semiconductor die;
• a second metal pillar coupled to the circuitry and extending away from the semiconductor die, a distance between the first and second metal pillars not exceeding 100 microns;
• a polyimide layer covering portions of the first and second metal pillars and covering a region between the first and second metal pillars, the polyimide layer in the region between the first and second metal pillars lacking a boundary between separate applications of polyimide to the region;
• a mold compound covering the polyimide layer in the region between the first and second metal pillars;
• and
• conductive terminals coupled to the first and second metal pillars and exposed to an exterior of the mold compound,
• wherein the polyimide layer in the region between the first and second metal pillars has a thickness ranging between 5 microns and 15 microns, and wherein the polyimide layer covers part, but not all, of a circumference of a top surface of the first metal pillar and part, but not all, of a circumference of a top surface of the second metal pillar.

A method for manufacturing a semiconductor package, comprising:

• forming one or more metal layers in a semiconductor die, the one or more metal layers coupled to circuitry of the semiconductor die;
• forming first and second metal pillars on the one or more metal layers, the first metal pillar separated from the second metal pillar by a distance not exceeding 100 microns;
• applying a polyimide layer to the one or more metal layers and to the first and second metal layers;
• positioning a reticle above the polyimide layer, the reticle including a first transmittance area positioned above an area of the polyimide layer on the one or more metal layers, a second transmittance area positioned above the polyimide layer on the first metal pillar, and a third transmittance area above the polyimide layer on a region between the first and second metal pillars, the third transmittance area having a light transmittance that is in between light transmittances of the first and second transmittance areas;
• applying light to the polyimide layer through the first, second, and third transmittance areas of the reticle;
• developing the polyimide layer;
• soldering the first and second metal pillars to conductive terminals;
• and
• covering the semiconductor die and the polyimide layer with a mold compound.