Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• semiconductor dies encapsulated in an encapsulant;
• and
• a redistribution structure, extending on the encapsulant and electrically connecting the semiconductor dies,
• wherein the redistribution structure comprises dielectric layers and redistribution conductive layers alternately stacked,
• an outermost dielectric layer of the dielectric layers further away from the semiconductor dies is made of a first material,
• a first dielectric layer of the dielectric layers on which the outermost dielectric layer extends is made of a second material different from the first material, and
• the redistribution structure further comprises under-bump metallurgies disposed on the outermost dielectric layer and extending through the outermost dielectric layer to land on wheel-shaped pads of the redistribution conductive layers, wherein the outermost dielectric layer fills in gaps directly under the under-bump metallurgies and penetrating through the wheel-shaped pads to directly contact the first dielectric layer,
• wherein a first under-bump metallurgy of the under-bump metallurgies corresponds to a first wheel-shaped pad of the wheel-shaped pads, and a size of the first under-bump metallurgy is greater than a size of the first wheel-shaped pad.