Hermetic wafer-to-wafer bonding with electrical interconnection

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second via, wherein the first conductive pad further comprising:
• forming a first conductive material on a thermal oxide material;
• forming a second conductive material over the first conductive material;
• and
• forming a third conductive material over the second conductive material.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the first conductive material consisting of titanium, the second conductive material consisting of gold (Au), and the third conductive material consisting of gold tin (AuSn).

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the first conductive material consisting of titanium, the second conductive material consisting of platinum (Pt), and the third conductive material consisting of AuSn.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the first conductive material consisting of Ti, the second conductive material consisting of Au, and the third conductive material consisting of AuSn.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the first conductive material consisting of Cr, the second conductive material consisting of Au, and the interconnect consisting of AuSn.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the first conductive pad and the second conductive pad consisting essentially of AuSn.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the Au is present in an amount of about 80 weight percent and Sn is present in an amount of 20 weight percent of the AuSn.

A method for forming an integrated circuit for an implantable medical device comprising:

• forming a first via in a first side of a first substrate;
• forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• forming a second via in a first side of a second substrate;
• forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• reflowing the first and second conductive pads to form a single reflowed interconnect that completely fills a gap between the first and second vias, wherein the Au is present in an amount of about 78 weight percent and Sn is present in an amount of 22 weight percent of the AuSn.

An integrated circuit for an implantable medical device comprising:

• means for forming a first via in a first side of a first substrate;
• means for forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• means for forming a second via in a first side of a second substrate;
• means for forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• means for heating until at least a portion of first and second conductive pads reflow and form an interconnect that completely fills a gap between the first and second vias, the first conductive pad comprising:
• means for forming a first conductive material on a thermal oxide material;
• and
• means for forming a second conductive material over the first conductive material.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect;
• a first conductive material coupled to the first conductive pad and to a thermal oxide material;
• a second conductive material coupled to the first conductive material;
• and
• a third conductive material coupled to the second conductive material.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect,
• wherein the first conductive material consisting of titanium, the second conductive material consisting of Au, and the third conductive material consisting of chromium AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect,
• wherein the first conductive material consisting of titanium, the second conductive material consisting of platinum (Pt), and the third conductive material consisting of AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect,
• wherein the first conductive material consisting of Ti, the second conductive material consisting of Au, and the third conductive material consisting of AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect,
• wherein the first conductive material consisting of Cr, the second conductive material consisting of Au, and the third conductive material consisting of AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect;
• and
• a fourth conductive material disposed over the third conductive material.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect, and
• wherein the first conductive material consisting of Ti, the second conductive material consisting of Ni, and the third conductive material consisting of Ti, and the fourth conductive material comprising AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect, wherein the first conductive pad and the second conductive pad consisting essentially of AuSn.

An implantable medical device comprising:

• a first substrate having a front side and a backside;
• a first via formed in the front side, the via extending from a bottom point in the front side to a first height located at a surface of the front side;
• a first conductive pad formed in the first via, the first conductive pad having an exposed top surface lower than first height;
• a second substrate coupled to the first substrate, the second substrate having a second via formed in the front side, the via extending from a bottom point in the front side to a second height located at a surface of the front side;
• a second conductive pad formed in the second via, the second conductive pad having an exposed top surface lower than second height;
• and
• means for reflowing one of the first and second conductive pads to form a single reflowed interconnect, wherein the Au is present in an amount of about 80 weight percent and tin (Sn) is present in an amount of 20 weight percent of the AuSn.

An integrated circuit for an implantable medical component comprising:

• means for forming a first via in a first side of a first substrate;
• means for forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• means for forming a second via in a first side of a second substrate;
• means for forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• means for heating until at least a portion of first and second conductive pads reflow and form an interconnect that completely fills a gap between the first and second vias, wherein the Au is present in an amount of about 79 weight percent and Sn is present in an amount of 21 weight percent of the AuSn.

An integrated circuit for an implantable medical component comprising:

• means for forming a first via in a first side of a first substrate;
• means for forming a first conductive pad in the first via, wherein an exposed top surface of the first conductive pad is lower than a top surface of the first via;
• means for forming a second via in a first side of a second substrate;
• means for forming a second conductive pad in the second via, wherein an exposed top surface of the second conductive pad is lower than a top surface of the second via;
• and
• means for heating until at least a portion of first and second conductive pads reflow and form an interconnect that completely fills a gap between the first and second vias, wherein the Au is present in an amount of about 78 weight percent and Sn is present in an amount of 22 weight percent of the AuSn.