Development of a chip prober for pre-bond testing of a 3D-IC

We developed a novel chip prober with a transparent membrane probe card for chip-level pre-bond testing of a three-dimensional integrated circuit. In the case of this chip prober, it was possible to achieve a uniform probing by using a parallelism-adjustment system with 3-point support. In addition, it was possible to achieve a small-gap alignment between the probe card and the tested chip by the precise control of the XYZθ stage and the transparency of the probe card. Thus, a high probing accuracy of ±2-3 μm was realized. A transparent membrane probe card was fabricated using a polyethylene naphthalate (PEN) film by through-holes formation with a UV-YAG laser beam, backside electrode formation, Ti-Au wiring formation, and Ni-Au contact bump formation. Owing to the deformation of the PEN film during probing, low-load probing (0.61 gf/pin) was realized. By using this chip prober, we could successfully conduct pre-bond testing of an SRAM/flash memory chip even when the chip was thinned down to 50 μm.