On-chip cooling systems for integrated circuits

A semiconductor structure fabrication method, comprising:

• providing a structure which includes:
• (a) a semiconductor substrate wherein the semiconductor substrate includes a top substrate surface,
• (b) a transistor on the semiconductor substrate,
• (c) N interconnect layers on top of the semiconductor substrate and the transistor,
• wherein the top substrate surface defines a reference direction perpendicular to the top substrate surface and pointing from the semiconductor substrate to the N interconnect layers,
• wherein each interconnect layer of the N interconnect layers includes an interlevel dielectric (ILD) layer and a metal line,
• wherein the metal line is electrically coupled to the transistor, and
• wherein N is a positive integer, and
• (d) a temporary filling region inside the semiconductor structure,
• wherein the temporary filling region comprises a temporary filling material;
• and
• heating the temporary filling region at a high temperature, resulting in a cooling pipes system in place of the temporary filling region,
• wherein the cooling pipes system does not include any solid or liquid material,
• wherein given any first point and any second point in the cooling pipes system, there exists a continuous path which connects the first and second points and which is totally within the cooling pipes system,
• wherein a first portion of the cooling pipes system overlaps the transistor in the reference direction,
• wherein a second portion of the cooling pipes system is higher than the semiconductor substrate and lower than a top interconnect layer of the N interconnect layers in the reference direction,
• wherein the second portion of the cooling pipes system is in direct physical contact with a surrounding ambient,
• wherein the first portion of the cooling pipes system is in direct physical contact with the surrounding ambient at a first interface between the first portion of the cooling pipes system and the ambient such that the first reference direction is perpendicular to the first interface,
• wherein the second portion of the cooling pipes system is in direct physical contact with the surrounding ambient at a second interface between the second portion of the cooling pipes system and the ambient such that a second reference direction is perpendicular to the second interface,
• wherein the second reference direction is perpendicular to the first reference direction, and
• wherein a totality of interfaces between the cooling pipes system and the ambient consists of the first interface and the second interface.

A semiconductor structure fabrication method, comprising:

• providing a structure which includes:
• (a) a semiconductor substrate wherein the semiconductor substrate includes a top substrate surface,
• (b) a transistor on the semiconductor substrate,
• (c) N interconnect layers on top of the semiconductor substrate and the transistor,
• wherein the top substrate surface defines a reference direction perpendicular to the top substrate surface and pointing from the semiconductor substrate to the N interconnect layers,
• wherein each interconnect layer of the N interconnect layers includes an interlevel dielectric (ILD) layer and a metal line,
• wherein the metal line is electrically coupled to the transistor, and
• wherein N is a positive integer, and
• (d) a temporary filling region inside the semiconductor structure,
• wherein the temporary filling region comprises a temporary filling material;
• and
• heating the temporary filling region at a high temperature, resulting in a cooling pipes system in place of the temporary filling region,
• wherein the cooling pipes system does not include any solid or liquid material,
• wherein a first portion of the cooling pipes system is in a top interconnect layer of the N interconnect layers in the reference direction,
• wherein a second portion of the cooling pipes system is in a next-to-top interconnect layer of the N interconnect layers,
• wherein the next-to-top interconnect layer is in direct physical contact with the top interconnect layer of the N interconnect layers,
• wherein given any first point and any second point in the cooling pipes system, there exists a continuous path which connects the first and second points and which is totally within the cooling pipes system,
• wherein the first portion of the cooling pipes system is in direct physical contact with a surrounding ambient,
• wherein the temporary filling material comprises ammonium hexafluorosilicate (NH4)2SiF6,
• wherein said heating the temporary filling region at the high temperature results in the temporary filling region evaporating,
• wherein no electrically conductive region of the semiconductor structure is in direct physical contact with the cooling pipes system,
• wherein the first portion of the cooling pipes system is in direct physical contact with the surrounding ambient at a first interface between the first portion of the cooling pipes system and the ambient such that the first reference direction is perpendicular to the first interface,
• wherein the second portion of the cooling pipes system is in direct physical contact with the surrounding ambient at a second interface between the second portion of the cooling pipes system and the ambient such that a second reference direction is perpendicular to the second interface,
• wherein the second reference direction is perpendicular to the first reference direction, and
• wherein a totality of interfaces between the cooling pipes system and the ambient consists of the first interface and the second interface.