Scratch protection for direct contact sensors
First Claim
1. A method of forming a scratch resistant integrated ciruit structure, comprising:
- forming an active region;
forming a dielectric overlying the active region; and
forming a capacitive-electrode over the dielectric proximate to a sensing surface on which an object is selectively placed to be sensed, the capacitive electrode forming a capacitor with the object when the object is placed on the sensing surface, wherein the capacitive electrode and each conductive region between the capacitive electrode and the active region are formed of a conductive material having a hardness greater than a hardness of aluminum.
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Abstract
In capacitive sensor circuits where physical contact is required and excess pressure may be inadvertently applied to the sensor surface, aluminum is not sufficiently hard to provide “scratch” protection and may delaminate, causing circuit failure, even if passivation integrity remains intact. Because hard passivation layers alone provide insufficient scratch resistance, at least the capacitive electrodes and preferably all metallization levels within the sensor circuit in the region of the capacitive electrodes between the surface and the active regions of the substrate are formed of a conductive material having a hardness greater than that of aluminum. The selected conductive material preferably has a hardness which is at least as great as the lowest hardness for any interlevel dielectric or passivation material employed. The selected conductive material is employed for each metallization level between the surface and the active regions, including contacts and vias, landing pads, interconnects, capacitive electrodes, and electrostatic discharge protection lines. Tungsten is a suitable conductive material, for which existing processes may be substituted in place of aluminum metallization processes.
38 Citations
20 Claims
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1. A method of forming a scratch resistant integrated ciruit structure, comprising:
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forming an active region;
forming a dielectric overlying the active region; and
forming a capacitive-electrode over the dielectric proximate to a sensing surface on which an object is selectively placed to be sensed, the capacitive electrode forming a capacitor with the object when the object is placed on the sensing surface, wherein the capacitive electrode and each conductive region between the capacitive electrode and the active region are formed of a conductive material having a hardness greater than a hardness of aluminum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
forming a passivation layer over the capacitive electrode, wherein the capacitive electrode and each conductive region between the capacitive electrode and the active region are formed of a conductive material having a hardness at least as great as a hardness of the passivation layer.
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4. The method of claim 1, wherein the capacitive electrode and each conductive region between the capacitive electrode and the active region are formed of tungsten.
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5. The method of claim 4, further comprising:
forming a tungsten via beneath the capacitive electrode.
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6. The method of claim 5, further comprising:
forming a tungsten interconnect beneath the via.
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7. The method of claim 6, further comprising:
forming a tungsten contact between the interconnect and the active region.
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8. The method of claim 7, wherein the active region is a gate electrode.
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9. A method of forming an integrated circuit structure, comprising:
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forming an active region;
forming a dielectric overlying the active region and having a contact opening therethrough;
forming a tungsten contact within the contact opening;
forming a tungsten metal region overlying the contact and a portion of the dielectric;
forming an interlevel dielectric overlying the tungsten metal region and the dielectric and having an opening therethrough;
forming a tungsten via within the opening through the interlevel dielectric; and
forming a tungsten capacitive electrode overlying the tungsten via and a portion of the interlevel dielectric and proximate to a sensing surface on which an object is selectively placed to be sensed, the capacitive electrode forming a capacitor with the object when the object is placed on the sensing surface, wherein the capacitive electrode is electrically connected to the active region by the contact, the metal region, and the via. - View Dependent Claims (10, 15)
forming an oxide over the capacitive electrode and the interlevel dielectric adjacent the capacitive electrode;
forming a passivation layer including a silicon nitride layer and a silicon carbide layer over the oxide; and
forming tungsten ESD protection within the passivation layer.
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15. The method of claim 10, wherein the passivation layer forms the sensing surface.
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11. A method of forming a scratch resistant integrated circuit structure, comprising:
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forming a plurality of active regions;
forming a dielectric over the plurality of active regions; and
forming an array of capacitive electrodes overlying the dielectric and proximate to a sensing surface on which an object is selectively placed to be sensed, the array of capacitive electrodes forming a capacitor with the object when the object is placed on the sensing surface, wherein the array of capacitive electrodes overlying the dielectric are formed of a conductive material having a hardness at least as great as a hardness of aluminum. - View Dependent Claims (12, 13, 14, 16, 17, 18, 19, 20)
forming the array of capacitive electrodes of a conductive material having a hardness at least as great as a hardness of a passivation layer overlying the array of conductive electrodes.
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13. The method of claim 11, wherein the step of forming an array of capacitive electrodes overlying the dielectric of a conductive material having a hardness at least as great as a hardness of aluminum further comprises:
forming the array of capacitive electrodes of tungsten.
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14. The method of claim 11, further comprising:
forming each metallization region between the array of capacitive electrodes and the plurality of active regions of a conductive material having a hardness at least as great as the hardness of the dielectric.
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16. The method of claim 12, further comprising:
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forming an oxide over the array of capacitive electrodes and the dielectric;
forming the passivation layer over the array of conductive electrodes, wherein the passivation layer includes a silicon nitride layer and a silicon carbide layer and overlies the oxide.
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17. The method of claim 16, wherein the passivation layer forms a sensing surface on which an object is selectively placed for sensing of features on the object, each capacitive electrode within the array forming a capacitor with the object when the object is placed on the sensing surface.
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18. The method of claim 12, further comprising:
forming tungsten ESD protection within the passivation layer.
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19. The method of claim 14, wherein each capacitive electrode within the array is connected to a corresponding active region by a contact within a contact opening through the dielectric, a metal region overlying the contact and a portion of the dielectric, a via within an opening through an interlevel dielectric overlying the metal region and the dielectric, wherein the step of forming each metallization region between the array of capacitive electrodes and the plurality of active regions of a conductive material having a hardness at least as great as the hardness of aluminum further comprises:
forming each contact, each metal region overlying a contact, and each via of tungsten.
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20. The method of claim 19, wherein at least some of the plurality of active regions are gate electrodes, the method further comprising:
forming each gate electrode of tungsten.
Specification