Cavendish Kinetics Limited

James F Bobey

Mickael Renault

Joseph Damian Gordon Lacey

Thomas L Maguire

Brian I Troy

Robertus Petrus Van Kampen

Vikram Joshi

The present invention generally relates to a method of fabricating a MEMS device. In the MEMS device, a movable plate is disposed within a cavity such that the movable plate is movable within the cavity. To form the cavity, sacrificial material may be deposited and then the material of the movable plate is deposited thereover. The sacrificial material is removed to free the mov able plate to move within the cavity. The sacrificial material, once deposited, may not be sufficiently planar because the height difference between the lowest point and the highest point of the sacrificial material may be quite high. To ensure the movable plate is sufficiently planar, the planarity of the sacrificial material should be maximized. To maximize the surface planarity of the sacrificial material, the sacrificial material may be deposited and then conductive heated to permit the sacrificial material to reflow and thus, be planarized.

Method of forming planar sacrificial material in a MEMS device

The present invention generally relates to a MEMS device in which silicon residues from the adhesion promoter material are reduced or even eliminated from the cavity floor. The adhesion promoter is typically used to adhere sacrificial material to material above the substrate. The adhesion promoter is the removed along with then sacrificial material. However, the adhesion promoter leaves silicon based residues within the cavity upon removal. The inventors have discovered that the adhesion promoter can be removed from the cavity area prior to depositing the sacrificial material. The adhesion promoter which remains over the remainder of the substrate is sufficient to adhere the sacrificial material to the substrate without fear of the sacrificial material delaminating. Because no adhesion promoter is used in the cavity area of the device, no silicon residues will be present within the cavity after the switching element of the MEMS device is freed.

Elimination of silicon residues from MEMS cavity floor

Embodiments discussed herein generally include methods of fabricating MEMS devices within a structure. The MEMS device may be formed in a cavity above the structure, and additional metallization may occur above the MEMS device. The cavity may be formed by depositing an encapsulating layer over the sacrificial layers that enclose the MEMS device. The encapsulating layer may then be etched to expose portions of the sacrificial layers. The sacrificial layers are exposed because they extend through the sidewalls of the encapsulating layer. Therefore, no release holes are etched through the top of the encapsulating layer. An etchant then removes the sacrificial layers to free the MEMS device and form the cavity and an opening through the sidewall of the encapsulating layer. Another encapsulating layer may then be deposited to seal the cavity and the opening.

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Gilroy, CA, United States of America

James F Bobey