In Micro Electro Mechanical Systems (MEMS) devices, mechanical and electronic components may be combined to form miniature electronic devices in sealed cavities. Although MEMS devices may take a variety of forms to perform various functions, in general, the cavities which are part of MEMS devices need to be sealed with a particular pressure, such as a sub-atmospheric pressure, to suit the needs of a particular application. Sealing the cavity of a MEMS device at a particular pressure provides the MEMS device with a desired operating pressure, which is designed to be impervious to changes in pressure that may be experienced by unsealed portions of the semiconductor die in which the MEMS device resides.
One commonly utilized technique for forming a sealed MEMS cavity involves placing two wafers in a special tool to form the sealed cavity in a pressurized environment. This technique results in relatively large physical dimensions of the MEMS cavity. Another technique involves dissecting a special lid from a wafer, forming a cavity in the wafer, and re-sealing the wafer with the special lid in a specially designed pressurized tool. This technique increases both production time and expense.
In addition, a drawback of employing traditional techniques of forming sealed cavities, such as those described above, is that in order to form multiple MEMS cavities, these processes need to be repeated for each MEMS cavity on the wafer. Moreover, employing the traditional approaches increases the risk of damage to the MEMS plates inside the MEMS cavity and results in impairment of device performance.
USPTO Backgrounds
USPTO Backgrounds