MEMS structure with improved shielding and method
A method for fabricating an integrated MEMS-CMOS device. The method can include providing a substrate member having a surface region and forming a CMOS IC layer having at least one CMOS device overlying the surface region. A bottom isolation layer can be formed overlying the CMOS IC layer and a shielding layer and a top isolation layer can be formed overlying a portion of bottom isolation layer. The bottom isolation layer can include an isolation region between the top isolation layer and the shielding layer. A MEMS layer overlying the top isolation layer, the shielding layer, and the bottom isolation layer, and can be etched to form at least one MEMS structure having at least one movable structure and at least one anchored structure.
1. A method for fabricating an integrated MEMS-CMOS device comprising:
providing a substrate member having a surface region;
forming a CMOS IC layer overlying the surface region, the CMOS IC layer having at least one CMOS device;
depositing a bottom isolation layer overlying the CMOS IC layer;
depositing a shielding layer overlying a portion of the bottom isolation layer, wherein a top surface of the shielding layer is coplanar to a top surface of the bottom isolation layer;
depositing a top isolation layer overlying a portion of the bottom isolation layer, wherein the bottom isolation layer comprises an isolation region between the top isolation layer and the shielding layer;
forming a MEMS layer overlying the top isolation layer, the shielding layer, and the bottom isolation layer; and
etching the MEMS layer to form at least one MEMS structure having at least one movable structure and at least one anchored structure, wherein the at least one anchored structure is coupled to a portion of the top isolation layer, wherein the at least one movable structure is formed overlying the shielding layer;
wherein the shielding layer is grounded to short plasma to the shielding layer to provide protection from charging during etching the MEMS layer.
2. The method of claim 1 wherein the shielding layer is formed within a portion of the bottom isolation layer.
3. The method of claim 1 wherein the shielding layer comprises a single-sided partial shielding layer underlying at least a portion of the movable structure.
4. The method of claim 1 wherein the shielding layer comprises a full shielding layer underlying at least a portion of the movable structure and at least a portion of the anchored structure.
5. The method of claim 4 further comprising etching the top isolation layer to form the isolation region between the top isolation layer and the bottom isolation layer.
6. The method of claim 1 wherein the shielding layer comprises a polysilicon material.
7. The method of claim 1 wherein the shielding layer comprises an aluminum material.
8. The method of claim 1 wherein the at least one MEMS structure comprises an accelerometer, a gyrometer, a magnetometer, or a pressure sensor.