Abstract: A monolithic silicon pressure sensor employing a four-terminal resistive element is formed in a thin monocrystalline silicon diaphragm. The resistive element is a diffused resistor having current contacts at the ends and two voltage contacts located midway between the current contacts and on opposite sides of a current axis defined between the two current contacts. The thin silicon diaphraghm has a square shape and is oriented in a (100) silicon surface with its sides parallel to a [110] crystal orientation. The resistor is oriented with its current axis parallel to a [100] crystalline direction and at 45 degrees with respect to the edge of the diaphragm to maximize sensitivity of the resistor to shear stresses generated by flexure of the diaphragm resulting from pressure differentials across the diaphragm.