In this letter, the fabrication of a compact and high performance semi-lumped coplanar waveguide low-pass filter (CPW-LPF) on high resistivity silicon (HRS) substrate at millimeter wave is proposed. The design procedure and the equivalent circuit of the proposed semi-lumped CPW-LPF is discussed. The filter structure of is very simple but its performances is fairly good. This designed filter at cutoff frequency fc of 31 GHz has very good measured characteristics including the low insertion loss, sharp rejection and low group delay, due to the reduced substrate loss of HRS. Experimental results of the fabricated filter show a good agreement with the predicted results.

For on-chip matching Si-MMIC fabricated on a conventional low resistivity Si substrate, the loss of on-chip inductors is quite high due to the dielectric loss of the substrate. In order to reduce the loss of on-chip matching circuit, the use of high resistivity Si substrate is quite effective. By using electro-magnetic simulation, the relationship between coplanar waveguide (CPW) transmission line characteristics and the resistivity of Si substrate is discussed. Based on the simulated results, the resistivity of Si substrate is designed to achieve lower dielectric loss than conductor loss. The effectiveness of high resistivity Si substrate is evaluated by the extraction of equivalent circuit model parameters of the fabricated on-chip spiral inductors and the measurement of the fabricated on-chip matching Si-MMIC LNA's.

We have improved the optical beam induced resistance change (OBIRCH) system so as to detect (1) a current path as small as 10-50 µA from the rear side of a chip, (2) current paths in silicide lines as narrow as 0. 2 µm, (3) high-resistance Ti-depleted polysilicon regions in 0. 2 µm wide silicide lines, and (4) high-resistance amorphous thin layers as thin as a few nanometers at the bottoms of vias. All detections were possible even in observation areas as wide as 5 mm 5 mm. The physical causes of these detections were characterized by focused ion beam and transmission electron microscopy.