Composite spring structure to reinforce mechanical robustness of a MEMS device

An integrated chip comprising:

• a microelectromechanical systems (MEMS) substrate comprising an anchor structure and a moveable element disposed next to the anchor structure;
• a carrier substrate underlying the MEMS substrate, wherein the MEMS substrate and the carrier substrate at least partially define a cavity within which the moveable element is in;
• and
• a composite spring extending continuously from the anchor structure to the moveable element, wherein the composite spring includes a first spring layer comprising monocrystalline silicon and a second spring layer comprising polysilicon, wherein a height of the first spring layer is equal to a height of the second spring layer.

An integrated chip, comprising:

• a first substrate;
• a second substrate disposed on the first substrate, wherein the first substrate and the second substrate at least partially define a cavity;
• a moveable element disposed within the cavity;
• and
• a composite spring extending from the moveable element to a peripheral region of the second substrate, wherein the composite spring comprises a first spring layer and a second spring layer that abut one another and continuously laterally extend from the peripheral region to the moveable element, wherein a bottom surface of the first spring layer is coplanar with a bottom surface of the second spring layer.