Package base structure and associated manufacturing method

A package base structure of a light emitting device and associated manufacturing method is provided. The method includes steps of forming a first mask layer and a second mask layer on a first surface and a second surface of a substrate; defining a first opening and a second opening on the first mask layer and the second mask layer wherein the first opening is larger than the second opening; etching the substrate to form the package base structure having a holding space and at least two through holes. The upper opening of the holding space is located on the first surface of the substrate, and the bottom of the holding space can support the light emitting device. The lower openings of the through holes are located on the second surface of the substrate, and the tops of the through holes reach the bottom of the holding space. There is at least one slant structure at the contact between sidewalls of the through holes and the bottom of the holding space.