This paper demonstrates a low loss fully embedded multilayer bandpass filter (BPF) using low-temperature cofired ceramic (LTCC) technology for 3-D integration of 40-GHz multimedia wireless system (MWS) radio. The LTCC filter implemented in a stripline configuration occupies an area of only 5.5 2.3 0.6 mm including shielding structure and coplanar waveguide (CPW) transitions. The measured insertion loss was as small as 1.9 dB at a center frequency of 41.8 GHz, and the return loss was 12.2 dB including the loss associated with two CPW-to-stripline transitions. This six-layer BPF showed 3-dB bandwidth of 10.5% from 39.6 to 44.0 GHz at a center frequency of 41.8 GHz and suppressed the local oscillator (LO) signal to 20.2 dB at a local oscillator frequency of 38.8 GHz, making it suitable for the 40 GHz MWS applications.Index Terms-Bandpass filter (BPF), embedded, low-temperature cofired ceramics (LTCC), multilayer, multimedia wireless systems (MWS).

A simple and easily manufacturable shallow trench isolation (STI) process is developed for 1 Gbit dynamic random access memory (DRAM) and possibly DRAMs with ever greater capacity. The main features of this STI scheme are dual slope trench formation and selective dry-etching-assisted chemical mechanical polishing (CMP) planarization. The dual slope trench is formed by utilizing polymer generation during trench etching to improve the sub-threshold conduction characteristics (hump-free sub-threshold) and reduce the threshold voltage variation. The basic elements of dry-etching-assisted planarization are to locally form oxide mesas using a highly selective dry etching, and to minimize the amount of CMP simply by removing the locally formed oxide mesas. This new dry-etching-assisted CMP planarization significantly reduces dishing in the large field area and improves the flatness between the high and low pattern density areas such as the cell array and periphery region in a high-density DRAM.

No abstract