Various embodiments of mechanisms for forming a die package using a compressive dielectric layer to contact and to surround through substrate vias (TSVs) in the die package are provided. The compressive dielectric layer reduces or eliminates bowing of the die package. As a result, the risk of broken redistribution layer (RDL) due to bowing is reduced or eliminated. In addition, the compressive dielectric layer, which is formed between the conductive TSV columns and surrounding molding compound, improves the adhesion between the conductive TSV columns and the molding compound. Consequently, the reliability of the die package is improved.