This paper proposes a new method of miniaturizing bulk-micromachined sensors. A Pyrex glass bonded to a silicon wafer replaces the silicon wafer as a substrate, because the silicon wafer can be machined to a diaphragm afterwards without wasting die area on {111}-faced slopes. Basically, this SOI(silicon-on-insulator)-like method produces sensor dies as small as surface-micromachined ones and is compatible with different techniques of making diaphragms. The silicon diaphragm on a glass substrate is mono-crystalline and has stable mechanical properties and reproducible behavior. The SOI-like method allows the fabrication of piezoresistive pressure sensors with a die size of 1.0 mm x 0.8 mm x 0.5 mm. Finite element analysis and pressure testing are compared to demonstrate the sensor performance of the prototype.