Multi-chip module with multi-level interposer

1. A multi-chip module (MCM), comprising:

a base plate;

a multi-level interposer plate having one or more first surfaces and one or more second surfaces associated with different thicknesses of the multi-level interposer plate, wherein a given first surface is associated with a first thickness of the multi-level interposer plate, wherein a given second surface is associated with a second thickness of the multi-level interposer plate, which is different than the first thickness, and wherein one or more first micro-spring connectors are disposed on the first surfaces and one or more second micro-spring connectors are disposed on the second surfaces; and

an array of chips that includes at least a first layer and a second layer, wherein the array of chips includes:

bridge chips in the first layer, wherein each bridge chip includes first connectors disposed on a surface of each bridge chip, which faces the given first surface, and which mechanically and electrically couple to the first micro-spring connectors; and

island chips in the second layer, wherein each island chip includes second connectors disposed on a surface of each island chip, which faces the given second surface, and which mechanically and electrically couple to the second micro-spring connectors.

2. The MCM of claim 1 , wherein the multi-level interposer plate includes a monolithic substrate having the first thickness in some regions and the second thickness in other regions.

3. The MCM of claim 2 , wherein the first thickness is less than the second thickness;

wherein the monolithic substrate includes through-substrate vias (TSVs) in the regions having the second thickness;

wherein the TSVs couple the second micro-spring connectors to connectors on a back surface of the multi-level interposer plate; and

wherein the connectors on the back surface are electrically coupled to corresponding connectors on the base plate.

4. The MCM of claim 1 , wherein the multi-level interposer plate includes multiple substrates, including first substrates having the first thickness and second substrates having the second thickness.

5. The MCM of claim 4 , wherein the first thickness is less than the second thickness;

wherein the second substrates include TSVs;

wherein the TSVs couple the second micro-spring connectors to connectors on back surfaces of the second substrates; and

wherein the connectors on the back surfaces are electrically coupled to corresponding connectors on the base plate.

6. The MCM of claim 1 , wherein overlapping, facing surfaces of a given island chip and a given bridge chip include proximity connectors that are configured to communicate signals via proximity communication.

7. The MCM of claim 6 , wherein the proximity communication includes optical proximity communication, capacitive proximity communication, inductive proximity communication or conductive proximity communication.

8. The MCM of claim 6 , wherein the overlapping, facing surfaces include negative alignment features; and

wherein the MCM further includes positive alignment features that mate with a given pair of the negative alignment features, thereby mechanically aligning the island chips and the bridge chips.

9. The MCM of claim 8 , wherein the negative alignment features include pits; and

wherein the positive alignment features include microspheres.

10. The MCM of claim 1 , wherein the first thickness is less than the second thickness.

11. The MCM of claim 10 , wherein the bridge chips are positioned in negative recesses in the multi-level interposer plate.

12. The MCM of claim 1 , wherein the first thickness is greater than the second thickness.

13. The MCM of claim 12 , wherein the island chips are positioned in negative recesses in the multi-level interposer plate.

14. The MCM of claim 1 , wherein the multi-level interposer plate includes side-wall interconnects disposed on side walls of the multi-level interposer plate between the first surfaces and the second surfaces; and

wherein the side-wall interconnects electrically couple the first micro-spring connectors and the second micro-spring connectors.

15. The MCM of claim 1 , wherein the second surfaces include first negative alignment features;

wherein the surface of each island chip includes second negative alignment features; and

wherein the MCM further includes positive alignment features that mate with a given pair of the first negative alignment features and the second negative alignment features, thereby mechanically aligning the island chips with respect to the multi-level interposer plate.

16. The MCM of claim 15 , wherein the first negative alignment features and the second negative alignment features include pits; and

wherein the positive alignment features include microspheres.

17. The MCM of claim 1 , wherein a sum of a thickness of the bridge chips and the first thickness approximately equals the second thickness.

18. A system, comprising an MCM, wherein the MCM includes:

a base plate;

a multi-level interposer plate having one or more first surfaces and one or more second surfaces associated with different thicknesses of the multi-level interposer plate, wherein a given first surface is associated with a first thickness of the multi-level interposer plate, wherein a given second surface is associated with a second thickness of the multi-level interposer plate, which is different than the first thickness, and wherein one or more first micro-spring connectors are disposed on the first surfaces and one or more second micro-spring connectors are disposed on the second surfaces; and

an array of chips that includes at least a first layer and a second layer, wherein the array of chips includes:

bridge chips in the first layer, wherein each bridge chip includes first connectors disposed on a surface of each bridge chip, which faces the given first surface, and which mechanically and electrically couple to the first micro-spring connectors; and

island chips in the second layer, wherein each island chip includes second connectors disposed on a surface of each island chip, which faces the given second surface, and which mechanically and electrically couple to the second micro-spring connectors.