CAP BONDING STRUCTURE AND METHOD FOR BACKSIDE ABSOLUTE PRESSURE SENSORS

摘要

A pressure sensor includes a pressure sensing element having a diaphragm, a cavity, and bridge circuitry connected to the diaphragm. A top surface is formed as part of the pressure sensing element such that at least a portion of the top surface is part of the diaphragm, and the plurality of piezoresistors are located on the top surface. A cap is bonded to the top surface through the use of a plurality of layers. One of the layers is a silicon dioxide layer, another layer is a silicon nitride layer, another layer is an oxide layer, and another of the layers is a polysilicon layer. The plurality of layers provides proper bonding between the cap and the top surface of the pressure sensing element.

主权项

1. An apparatus, comprising:
a pressure sensor, including:
a pressure sensing element;a cavity formed as part of the pressure sensing element;a first layer formed on the to surface of the pressure sensing element;a second layer deposited on the first layer;a third layer deposited on the second layer;a fourth layer deposited on the third layer;a cap bonded to the fourth layer; anda diaphragm formed as part of the pressure sensing element, such that at least part of the diaphragm forms part of the cavity;wherein the width of the fourth layer is greater than the width of the cap.