High bandwidth package structure

A semiconductor structure, comprising:

• a first substrate;
• a first interconnect structure disposed over the first substrate;
• a first bonding layer disposed on the first interconnect structure;
• a second bonding layer disposed on and bonded to the first bonding layer;
• a second interconnect structure disposed over the second bonding layer;
• a second substrate disposed over the second interconnect structure;
• a multi-layer protective film disposed on the second substrate;
• a frontside through via extending from the second interconnect structure into the second substrate such that a top surface of the frontside through via is spaced apart from the multi-layer protective film by a depth of the second substrate;
• and
• a backside through via extending through the multi-layer protective film and the depth of the second substrate to interface the frontside through via.

A method, comprising:

• receiving a first wafer that includes:
• a first substrate, and
• a first interconnect structure over the first substrate;
• receiving a second wafer that includes:
• a second substrate,
• a second interconnect structure over the second substrate, and
• a through via extending through a portion of the second substrate and a portion of the second interconnect structure;
• forming a first bonding layer on the first interconnect structure;
• forming a second bonding layer on the second interconnect structure;
• bonding the second wafer to the first wafer by directly bonding the second bonding layer to the first bonding layer;
• after the bonding, thinning the second substrate until a top surface of the through via is a depth away from a surface of the second substrate away from the second interconnect structure;
• forming a multi-layer protective film over the thinned second substrate;
• forming a backside via opening through the multi-layer protective film and the thinned second substrate to expose the through via;
• conformally depositing a liner over the multi-layer protective film and the backside via opening;
• anisotropically etching back the liner to expose the through via;
• and
• after the anisotropically etching back, depositing a metal material over the backside via opening.