Pre‐Bond Testing Through Direct Probing of Large‐Array Fine‐Pitch Micro‐Bumps*

In order to obtain acceptable compound stack yields for 2.5D‐ and 3D‐stacked integrated circuits (SICs), there is a need to test the constituting dies before stacking. The non‐bottom dies of these stacks have their functional access exclusively through large arrays of fine‐pitch micro‐bumps, which are too dense for conventional probe technology. A common approach to obtain pre‐bond test access is to equip these dies with dedicated pre‐bond probe pads, which comes with drawbacks such as increased silicon area and test application time and reduced interconnect performance. In order to avoid the many drawbacks of dedicated pre‐bond probe pads, we advocate the usage of advanced probe technology that allows to directly probe on these micro‐bumps. This chapter reports on the technical feasibility of this approach. The economical feasibility is addressed in Chapter 9.