PMMA sacrificial layer based reliable debonding of ultra-thin chips after lapping

Ultra-thin chips (UTCs) are needed to meet the performance and packaging related requirements of flexible electronics and 3D integrated circuits (ICs). However, handling of UTCs (<50 μm thick), particularly after thinning, is a challenging task as the excessive mechanical stresses could lead to cracking. Such damages could be prevented by restricting the stresses to acceptable levels. Herein, we present a new reliable and cost-effective method based on a polymethylmethacrylate (PMMA) sacrificial layer (20 μm-thick). The PMMA layer results in 4 order of magnitude lower stress on UTCs and, as a result, the reliable removal or debonding of UTCs (35 μm-thick) from the glass substrate has been achieved. The distinctive features of the presented method are high reliability and cost-effectiveness (an order of magnitude cheaper) with respect to conventional methods that use UV curable tapes. The UTCs with metal-oxide-semiconductor capacitors (MOSCAPs) devices were also obtained using this approach and were evaluated under different bending conditions. The stable and uniform performance (134 pF) observed under bending conditions demonstrates that the presented technique could be useful for integration of high-performance flexible UTCs on flexible printed circuit boards for various practical application.