Methods of forming a semiconductor package including stress buffers

A semiconductor package comprising:

• a semiconductor die;
• a first underfill layer disposed under the semiconductor die;
• a redistribution layer (RDL) disposed under the first underfill layer and having a first Young's modulus;
• and
• a stress buffer embedded in a top surface of the RDL below a corner of the semiconductor die in a top view and directly contacting the first underfill layer, the stress buffer having a second Young's modulus that is at least 30% less than the first Young's modulus.

A semiconductor package comprising:

• a first semiconductor device and a second semiconductor device;
• a first underfill layer disposed under the first and second semiconductor devices;
• a dielectric material and metal features disposed under the first underfill layer, the dielectric material having a first Young's modulus;
• and
• stress buffers embedded in the dielectric material below corners of at least one of the first and second semiconductor devices in a top view and directly contacting the first underfill layer, the stress buffers having a second Young's modulus that is at least 30% less than the first Young's modulus.