Create a protected layer for interconnects and devices in a packaged quantum structure

A method, comprising:

• forming a first chip layer, having a first chip layer front-side and a first chip layer back-side;
• forming a set of bump bonds on the first chip layer front-side;
• forming a qubit chip layer, having a qubit chip layer front-side and a qubit chip layer back-side, the qubit chip layer front-side operatively coupled to the first chip layer front-side with the set of bump bonds;
• forming a set of through-silicon vias (TSVs) connected to at least one of:
• the first chip layer back-side or the qubit chip layer back-side;
• and
• forming a cap wafer metal bonded to at least one of:
• the qubit chip layer back-side or the first chip layer back-side.

A device, comprising:

• a first chip layer, having a first chip layer front-side and a first chip layer back-side;
• a qubit chip layer, having a qubit chip layer front-side and a qubit chip layer back-side, the qubit chip layer front-side operatively coupled to the first chip layer front-side with a set of bump bonds;
• a set of through-silicon vias (TSVs) connected to at least one of:
• the first chip layer back-side or the qubit chip layer back-side;
• a cap wafer metal bonded to at least one of:
• the qubit chip layer back-side or the first chip layer back-side wherein the cap wafer comprises at least one cavity comprising an inter-connection material;
• and
• wherein the at least one of the qubit chip layer back-side or the first chip layer back-side is operatively coupled to at least one of:
• a filter, a qubit feed line, a resonator, or a coupler;
• and
• wherein a set of qubits of the qubit chip layer are on an exposed surface, and the set of qubits are connected by in-plane buses and buried layer buses.