Scalable Hyper-Thinning of Si for Three-Dimensional Space Electronics

This phase I proposal addresses ultra-thinning (~ 5-10 micrometer) of Si wafers and memory dies through a mix and match approach in which advanced deep reactive ion etching (DRIE)and pulsed laser etching (PLE)methods are used for coarse and plasmaless XeF2 vapor etching for fine thinning. Die-thinning in sub 10-micrometer regime is a subject of enduring interest in ultra-dense 3D MCM packaging and radiation-toleration enhancement of Si circuits for space environment. Considering the inability of processing ultra-thin dies and wafers, die-thinning is ideally done following circuit fabrication and lamination to a carrier substrate. Both DRIE and PLE methods are desirable for their low-temperature directional etching. Pulsed laser methods are also attractive due to their direct writing capabiity. Intial experiments using DRIE and XeF2 etching methods have demonstrated the feasibility of this concept. In this phase I proposal, we will conduct comparative assessment of both DRIE and PLE approaches to determine an optimum thinning method in terms of resolution, uniformity, cost, and througput. In collboration with GE Global Research, we will evaluate radiation tolerance of ultra-thinned memory dies during phase I and develop ultra-dense 3D MCM packaging during phase II.