Methods and apparatus for thermal isolation in vertically-integrated semiconductor devices
View Patent ↗A semiconductor structure ( 100 ) includes a first substrate ( 110 ) having a first semiconductor device ( 112 ) formed therein, a second substrate ( 120 ) having a second device ( 122 ) formed therein and vertically-integrated above the first substrate ( 110 ), and a thermal isolation gap ( 130 ) disposed between the first device ( 112 ) and the second device ( 122 ). The thermal isolation gap ( 130 ) may be formed, for example, using an etched dielectric layer formed on first substrate ( 110 ), using an etched cavity in the second substrate ( 120 ), or by including a bonding layer ( 140 ) that has a gap or void incorporated therein.
1. A semiconductor structure comprising:
a first substrate having a first semiconductor device formed therein;
a second substrate having a second device formed therein, wherein the second substrate is vertically-integrated with the first substrate such that they are electrically communicative;
a thermal isolation gap disposed between the first device and the second device; and
a bonding layer provided between substantially the entire area of the first substrate and the second substrate such that the bonding layer is in a conduction heat transfer path of at least one of the first and second devices, and wherein the thermal isolation gap is disposed within the bonding layer.
2. The semiconductor structure of claim 1 , wherein the bonding layer comprises a material selected from the group consisting of polymers, metals, dielectrics, and semiconductors.
3. The semiconductor structure of claim 1 , further including a hot-spot region proximate the first semiconductor device, wherein the thermal isolation gap is located substantially adjacent the hot-spot region.
4. The semiconductor structure of claim 3 , wherein the hot-spot region has a first center, the thermal isolation gap has a second center, and wherein the first center and the second center are substantially aligned.
5. The semiconductor structure of claim 1 , the first substrate further including a through-wafer via extending therethrough.
6. The semiconductor structure of claim 1 , further including a heat spreader thermally communicating with the second device.
7. The semiconductor structure of claim 1 , wherein the first substrate is a wafer, and the second substrate is a semiconductor die.
8. The semiconductor structure of claim 1 , wherein the first substrate is a wafer, and the second substrate is a wafer.
9. The semiconductor structure of claim 1 , wherein the first substrate is a semiconductor die and the second substrate is a semiconductor die.
10. The semiconductor structure of claim 1 , wherein the thermal isolation gap is substantially a vacuum.
11. The semiconductor structure of claim 1 , wherein the thermal isolation gap further comprises a cavity within the second substrate.
12. The semiconductor structure of claim 11 , wherein the cavity is an etched cavity.
13. The semiconductor structure of claim 1 , wherein the thermal isolation gap comprises a gap formed within a conformal coating provided on a dielectric layer, the dielectric layer being formed on the first substrate.
14. A method for forming a vertically-integrated semiconductor structure, the method comprising:
providing a first substrate having a first device formed therein and an predetermined hot-spot region proximate the first device;
providing a second substrate; and
forming a bonding layer between substantially the entire area of the first substrate and the second substrate such that the bonding layer is in a conduction heat transfer path of at least one of the first and second devices, and wherein a thermal isolation gap is formed within the bonding layer substantially above the predetermined hot-spot region and such that the first substrate and second substrate are electrically communicative.
15. The method of claim 14 , wherein the bonding step includes providing a bonding layer comprising a material selected from the group consisting of polymers, metals, and dielectrics.
16. The method of claim 14 , further including forming a through-wafer via in the first substrate.
17. The method of claim 14 , further including forming a heat spreader in thermal communication with the second device.
18. The method of claim 14 , wherein bonding the first substrate to the second substrate includes bonding the second substrate to conformal coating formed on a dielectric layer on the first substrate, wherein the thermal isolation gap is partially bounded by the conformal coating.
19. The method of claim 14 , further including etching the second substrate to form the thermal isolation gap.