Jörg Dr. Kiesewetter

Direct probing on large-array fine-pitch micro-bumps of a wide-I/O logic-memory interface

In order to obtain acceptable compound stack yields for 2.5D- and 3D-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, 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 paper reports on the technical and economical feasibility of this approach.

A fully automatic test system for characterizing large-array fine-pitch micro-bump probe cards

A fully automatic test system for characterizing advanced probe cards able to probe on large-array fine-pitch micro-bumps (such as JEDECs Wide-I/O Mobile DRAM interfaces [1, 2]) has been specified, developed, installed, and brought to a full-operational state. The system is based on a Cascade CM300 probe station from FormFactor and National Instruments PXI test instrumentation and complemented by in-house developed software for automatic test generation and data analysis and visualization. The system is successfully used in conjunction with FormFactors Pyramid Probe® RBI probe-card technology on WIO1 and WIO2 micro-bump arrays on 0300mm wafers designed and manufactured by IMEC. This paper describes the various system components in hardware and software, and experimental results obtained with several test wafers.