On-chip interconnect-stack cooling using sacrificial interconnect segments
View Patent ↗The present invention relates to an integrated-circuit device and to a method for fabricating an integrated-circuit device with an integrated fluidic-cooling channel. The method comprises forming recesses in a dielectric layer sequence at desired lateral positions of electrical interconnect segments and at desired lateral positions of fluidic-cooling channel segments. A metal filling is deposited in the recesses of the dielectric layer sequence so as to form the electrical interconnect segments and to form a sacrificial filling in the fluidic-cooling channel segments. Afterwards, the sacrificial metal filling is selectively removed from the fluidic-cooling channel segments.
1. An integrated-circuit device with a fluidic-cooling channel comprising:
a silicon substrate with an integrated circuit, the integrated circuit including a transistor structure that comprises contact elements, at least some of the contact elements of the transistor structure being located in the silicon substrate; and
an interconnect stack formed on the silicon substrate, the interconnect stack having electrical interconnect segments on one or more interconnect levels and a dielectric layer sequence with a respective intralevel dielectric layer on a respective associated interconnect level of the one or more interconnect levels, electrically isolating different electrical interconnect segments on the associated interconnect level from each other,
wherein the interconnect stack comprises the fluidic-cooling channel that extends to at least one of the one or more interconnect levels of the interconnect stack and through at least one interlevel metallization barrier layer in the interconnect stack, and
wherein the fluidic-cooling channel extends between a fluidic-cooling input interface to receive a fluidic cooling medium from an external fluidic-cooling circulation driver and a fluidic-cooling output interface to transmit the fluidic cooling medium to the external fluidic-cooling circulation driver, both of the fluidic-cooling input interface and the fluidic-cooling output interface being provided on a substrate outer face of the silicon substrate or on a stack outer face of the interconnect stack, the substrate outer face of the silicon substrate and the stack outer face of the interconnect stack being on opposite sides of the integrated-circuit device.
2. The integrated-circuit device of claim 1 , wherein sidewalls of the fluidic-cooling channel are covered with a dielectric liner, which is adapted to form a barrier for avoiding a contact between the fluidic cooling medium and a surrounding material of the intralevel dielectric layer or the at least one interlevel metallization barrier layer.
3. The integrated-circuit device of claim 1 , further comprising a sealing layer which seals the highest interconnect level so as to prevent a discharge of a cooling fluid from the fluidic-cooling channel.
4. The integrated-circuit device of claim 1 , wherein the fluidic-cooling channel extends into the silicon substrate.
5. The integrated-circuit device of claim 1 , wherein the fluidic-cooling input interface and the fluidic-cooling output interface are provided on the substrate outer surface of the silicon substrate.
6. The integrated-circuit device of claim 1 , wherein the fluidic-cooling channel comprises intralevel cooling-channel segments, which extend on a respective interconnect level of the one or more interconnect levels, and the intralevel cooling-channel segments are confined by a respective interlevel metallization barrier layer of the at least one interlevel metallization barrier layer on either a top side, which faces away from the silicon substrate, or on a bottom side, which faces towards the silicon substrate, and which are further confined by an interlayer dielectric layer of the intralevel dielectric layers.
7. The integrated-circuit device of claim 6 , wherein the fluidic-cooling channel comprises a cooling-channel via segment, which forms a via hole in the respective interlevel metallization barrier layer and in an adjacent section of the intralevel dielectric layer, and wherein the cooling-channel via segment has a lateral extension that is smaller than that of the intralevel cooling-channel segments in one or both lateral directions.
8. The integrated-circuit device of claim 1 , wherein the fluidic-cooling channel comprises an input trunk channel segment near the fluidic-cooling input interface and an output trunk channel segment near the fluidic-cooling output interface, and branch channels, which are connected between the input trunk channel segment and the output trunk channel segment.
9. The integrated circuit device of claim 1 , wherein the at least one interlevel metallization barrier layer is arranged between two associated neighboring interconnect levels of the one or more interconnect levels, and which electrically isolates the different electrical interconnect segments on the associated neighboring interconnect levels from each other.
10. The integrated circuit device of claim 1 , wherein the fluid cooling channel and the electrical interconnect segments have same design configurations as result of following the same design rules.
11. A method for fabricating an integrated-circuit device with an integrated fluidic-cooling channel, comprising:
providing a silicon substrate with an integrated circuit, the integrated circuit including a transistor structure that comprises contact elements, at least some of the contact elements of the transistor structure being located in the silicon substrate;
depositing a dielectric layer sequence on the silicon substrate comprising at least one intralevel dielectric layer to form an interconnect stack on the silicon substrate, an interlevel metallization barrier layer on the dielectric sequence;
forming a mesh of lines in the interconnect stack on the silicon substrate as to form electrical interconnect segments in the interconnect stack and a sacrificial filling in fluidic-cooling channel segments in the interconnect stack;
selectively removing the sacrificial filling from the fluidic-cooling channel segments in the interconnect stack on the silicon substrate,
wherein the fluidic-cooling channel segments are formed to extend between a fluidic-cooling input interface to receive a fluidic cooling medium from an external fluidic-cooling circulation driver and a fluidic-cooling output interface to transmit the fluidic cooling medium to the external fluidic-cooling circulation driver, both of the fluidic-cooling input interface and the fluidic-cooling output interface being provided on a substrate outer face of the silicon substrate or on a stack outer face of the interconnect stack, the substrate outer face of the silicon substrate and the stack outer face of the interconnect stack being on opposite sides of the integrated-circuit device.
12. The method of claim 11 , wherein the step of forming the mesh of lines comprises:
forming recesses in the dielectric layer sequence at desired lateral positions of the electrical interconnect segments and at desired lateral positions of the fluidic-cooling channel segments; and
depositing a metal filling in the recesses of the dielectric layer sequence so as to form the electrical interconnect segments and the fluidic-cooling channel segments, wherein the metal filling in the fluidic-cooling channel segments is the sacrificial filling.
13. The method of claim 12 , wherein the step of depositing the metal filling in the recesses of the dielectric layer sequence comprises removing the interlevel metallization barrier layer from a recess of the recesses before the deposition of the metal filling.
14. The method of claim 11 , wherein the step of selectively removing the sacrificial filling comprises
depositing a mask layer on an interlevel metallization barrier layer,
forming an opening in the mask layer and in the interlevel metallization barrier layer at the at desired lateral positions of the fluidic-cooling channel,
removing the mask layer, and
selectively etching the sacrificial filling through the opening in the interlevel metallization barrier layer.
15. The method of claim 11 , wherein the step of selectively removing the sacrificial filling comprises
depositing a mask layer on an interlevel metallization barrier layer,
forming an opening in the mask layer and in the interlevel metallization barrier layer at the at desired lateral positions of the fluidic-cooling channel,
removing the mask layer, and
performing a reverse electrolysis etching step of the sacrificial filling using a contact formed by the silicon substrate and an electrically conductive connection between the silicon substrate and the sacrificial filling in the recess for the fluidic-cooling channel.
16. The method of claim 11 , further comprising a step of forming a thermally conductive plug on the silicon substrate at a desired lateral position for establishing a thermally conductive connection between the silicon substrate and a fluidic-cooling channel segment of the fluidic-cooling channel segments to be formed afterwards.
17. The method of claim 11 , further comprising a step of sealing the fluidic-cooling channel segments of the highest interconnect level.
18. The method of claim 11 , further comprising a step of forming a fluidic-cooling channel of the fluidic-cooling channel segments in the silicon substrate and a step of forming the fluidic-cooling input interface and the fluidic-cooling output interface to the fluidic-cooling channel in the interconnect stack.
19. The method of claim 11 , wherein the fluidic-cooling input interface and the fluidic-cooling output interface are provided on the substrate outer surface of the silicon substrate.