Carrier substrate

A carrier substrate, comprising:

• a first circuit structure comprising a first dielectric layer and a first circuit layer formed on the first dielectric layer, wherein the first circuit structure is defined with a plurality of first routing regions on an outermost side of the first dielectric layer, such that one of the plurality of first routing regions is defined as a first target region;
• and
• a second circuit structure disposed on a side of the first circuit structure, and the second circuit structure comprising a second dielectric layer and a second circuit layer formed on the second dielectric layer, wherein the second circuit structure is defined with a plurality of second routing regions on an outermost side of the second dielectric layer, such that one of the plurality of second routing regions is defined as a second target region with the same shape and area as the first target region, and a position of the first target region and a position of the second target region are overlapped and aligned with each other, so that a difference between a routing ratio of the first circuit layer on the first target region and a routing ratio of the second circuit layer on the second target region is within 10%,
• wherein the first circuit structure is served as an outer side of the carrier substrate, and the second circuit structure is served as another outer side of the carrier substrate.