Method of fabricating an integrated device
A method of fabricating an integrated device including a MicroElectroMechanical system (MEMS) and an associated microcircuit is provided. In one embodiment, the method comprises: forming a high temperature capable contact through a dielectric layer to an underlying element of a microcircuit formed adjacent to a MicroElectroMechanical System (MEMS) structure on a substrate; and depositing a layer of conducting material over the dielectric layer, and patterning the layer of conducting material to form a local interconnect (LI) for the microcircuit overlying and electrically coupled to the contact and a bottom electrode for the adjacent MEMS structure. Other embodiments are also provided.
1. A method of fabricating an integrated device comprising:
forming a contact opening through a dielectric layer to an underlying structure of a microcircuit on a substrate;
depositing a seed layer comprising a refractory metal on a surface of the contact opening, wherein depositing the seed layer comprises depositing from 100 to 1000 Å of titanium (Ti), and further depositing from 100 to 1000 Å of titanium-tungsten (TiW);
nitriding the seed layer to form a barrier layer on a surface thereof;
depositing a metal over the barrier layer to form a high temperature contact in the opening;
forming a temperature resistant cap over the high temperature contact; and
fabricating a MicroElectroMechanical System (MEMS) on the substrate using high temperature processing steps,
wherein at least a portion of the MEMS overlies and electrically couples to the high temperature contact.
2. A method according to claim 1 , wherein nitriding the seed layer comprises heating the substrate in a nitrogen containing atmosphere.
3. A method according to claim 2 , wherein heating the substrate comprises heating the substrate to a temperature of between 750 to 950° C. to sinter the seed layer.
4. A method according to claim 3 , wherein heating the substrate in a nitrogen containing atmosphere comprises introducing ammonia (NH3) into a process chamber of a process tool at a flow rate of between 10 to 10,000 standard cubic centimeters per minute (sccm).
5. A method according to claim 3 , wherein heating the substrate comprises heating the substrate in a rapid thermal processing (RTP) tool for between 10 to 500 seconds.
6. A method according to claim 1 , further comprising cleaning the contact opening using an RF sputter etch-clean prior to depositing the seed layer.
7. A method according to claim 1 , wherein depositing a metal over the barrier layer to form the contact in the opening comprises depositing tungsten (W).
8. A method according to claim 7 , further comprising planarizing the tungsten using chemical mechanical planarization (CMP) prior to forming the temperature resistant cap over the contact.
9. A method according to claim 1 , wherein forming the temperature resistant cap over the contact comprises forming a polysilicon local interconnect (LI) covered by an oxide over the contact.