Sputtered spring films with low stress anisotropy

A spring structure comprising:

• a substrate;
• and
• a substrate having an upper surface defining a plane;
• and
• a spring finger formed from a stress-engineered film deposited over the substrate, the spring finger having an anchor portion attached to the substrate and defining a second plane that is parallel the first plane, the spring finger also having a curved free portion extending from the anchor portion and bending out of the second plane away from the substrate,
• wherein the spring finger is formed from a spring material defining a compressive saturation point and a tensile saturation point, and
• wherein the anchor portion of the spring finger includes at least one layer having an internal stress that is at one of the compressive saturation point and the tensile saturation point.

A method for forming a spring structure, the method comprising:

• forming a release material layer over a substrate;
• forming a spring material island on the release material layer, the spring material island having a stress variation in a direction normal to the substrate and including at least one layer having an isotropic internal stress;
• and
• etching a portion of the release material layer, thereby forming a spring finger having an anchor portion attached to the substrate and a free portion bending away from the substrate due to the internal stress gradient.

A method for fabricating a spring structure, the method comprising:

• forming a release material layer over a substrate, forming a first layer of a spring material over the release material layer such that the first layer has a compressive internal stress;
• forming a second layer of the spring material over the first layer such that the second layer has a tensile internal stress;
• and
• selectively removing a first portion of the release material layer from beneath a free portion of first and second layers using a release mask that covers an anchor portion of the first and second layers, where upon removing the first portion of the release material layer, the internal stresses of the first and second layers cause the free portion of the first and second layers to bend relative to the substrate, thereby forming a spring finger,
• wherein at least one of the compressive internal stress of the first layer and the tensile internal stress of the second layer is isotropic.

A method for forming a spring structure, the method comprising:

• forming a release material layer over a substrate;
• depositing a spring material film on the release material layer at an argon pressure greater than 4 mT while varying at least one of substrate temperature and applied RF bias such the spring material film has an internal stress variation in the growth direction;
• and
• etching a portion of the release material layer, thereby forming a spring finger having an anchor portion attached to the substrate and a free portion bending away from the substrate due to the internal stress gradient.

A method for forming a spring structure, the method comprising:

• forming a release material layer over a substrate;
• depositing spring material atoms from a target toward the substrate to grow a spring material film on the release material layer, wherein the deposition is controlled such that a majority of the spring material atoms that hit the growing spring material film are moving normal to the substrate;
• and
• etching a portion of the release material layer, thereby forming a spring finger having an anchor portion attached to the substrate and a free portion bending away from the substrate due to the internal stress gradient.

An integrated processing tool comprising:

• a central transfer chamber including a robot for transferring wafers into and out of said central transfer chamber;
• a first physical vapor deposition chamber directly accessible via a valve with said central transfer chamber, having a target comprising a selected release material;
• and
• a second physical vapor deposition chamber directly accessible via a valve with said central transfer chamber, having a target comprising a selected spring material.

A method for producing a spring structure on a wafer utilizing an integrated multi-chamber tool having a central transfer chamber including a robot for transferring the wafer into and out of the central transfer chamber, a first physical vapor deposition chamber directly accessible via a valve with said central transfer chamber and having a first target comprising a selected release material, and a second physical vapor deposition chamber directly accessible via a valve with said central transfer chamber and having a second target comprising a selected spring material, the method comprising:

• causing the robot to position the wafer in the first physical vapor deposition chamber;
• controlling the first physical vapor deposition chamber to deposit a release material layer on the wafer from the first target;
• causing the robot to remove the wafer from the first physical vapor deposition chamber and to position the wafer in the second physical vapor deposition chamber;
• controlling the second physical vapor deposition chamber to deposit a spring material layer on the release material layer from the second target such that the spring material film has a stress variation in the growth direction and including at least one layer having an isotropic internal stress.