Copper metallization structure and method of construction
First Claim
1. A process of fabricating a conductive layer on a substrate, the process comprising the steps of:
- preparing a boundary layer on the substrate; and
depositing a conductive layer directly on the boundary layer without any seed layer, wherein said depositing step comprises the substeps of applying a first control parameter until a condition subsequent occurs, and applying a second control parameter after occurrence of the condition subsequent;
wherein the semiconductor substrate is silicon, the conductive layer is a metallic material having diffusion limited by the boundary layer, wherein the boundary layer is a diffusion barrier layer, and wherein said substep of applying a first control parameter includes applying a first voltage, and said substep of applying a second control parameter includes applying a second voltage which is more positive than the first voltage.
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Abstract
The invention is directed to the use of copper as via and interconnect structures for an integrated circuit. The process in accordance with a preferred embodiment produces an interconnect layer of continuous copper with superior adhesion while requiring only a minimum number of steps for its production. This process addresses the current need in semiconductor manufacturing for reliable and performance-oriented vias and interconnect structures, while not being susceptible to many of the problems which plague the use of aluminum for similar structures. Fabrication of an integrated circuit in accordance with a preferred embodiment of the invention begins with the formation of semiconductor devices on a silicon wafer. Next, an intermetallic dielectric layer (IDL) is formed by materials such as silicon dioxide (SiO2), polymide, or silicon nitride over the devices. This step is followed by the laying of a diffusion barrier layer on the IDL surface. The resulting product is then exposed to an electrochemical deposition or electroplating stage for the formation of a copper layer directly on top of the diffusion barrier layer. In accordance with a preferred embodiment of the invention, a variable voltage is applied to the electrochemical process in two different stages. The first stage produces nucleation of a high density of clusters and the second stage permits diffusion limited growth of the clusters so as to produce a continuous copper film layer.
58 Citations
15 Claims
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1. A process of fabricating a conductive layer on a substrate, the process comprising the steps of:
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preparing a boundary layer on the substrate; and
depositing a conductive layer directly on the boundary layer without any seed layer, wherein said depositing step comprises the substeps of applying a first control parameter until a condition subsequent occurs, and applying a second control parameter after occurrence of the condition subsequent;
wherein the semiconductor substrate is silicon, the conductive layer is a metallic material having diffusion limited by the boundary layer, wherein the boundary layer is a diffusion barrier layer, and wherein said substep of applying a first control parameter includes applying a first voltage, and said substep of applying a second control parameter includes applying a second voltage which is more positive than the first voltage. - View Dependent Claims (2, 3)
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4. A process of fabricating a conductive layer on a substrate, the process comprising the steps of:
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preparing a boundary layer on the substrate; and
depositing a conductive layer directly on the boundary layer without any seed layer, wherein said depositing step comprises the substeps of applying a first control parameter until a condition subsequent occurs, and applying a second control parameter after occurrence of the condition subsequent;
wherein said substep of applying a first control parameter involves application of a negative voltage sufficient to produce nucleation of a high density of hemispherical clusters to make up the conductive layer, and wherein said substep of applying a second control parameter involves increasing the applied first control parameter to a level that permits growth of the hemispherical clusters to form a continuous and adherent film. - View Dependent Claims (5, 6, 7)
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8. A process of fabricating a conductive layer on a substrate, the process comprising the steps of:
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preparing a boundary layer on the substrate; and
depositing a conductive layer directly on the boundary layer without any seed layer, wherein said depositing step comprises the substeps of applying a first control parameter until a condition subsequent occurs, and applying a second control parameter after occurrence of the condition subsequent;
wherein the first control parameter is a first current level, and the second control parameter is a second current level which is smaller than the first current level.
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9. A process of depositing copper on a semiconductor substrate, the process comprising the steps of:
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forming a dielectric layer on at least one surface of the semiconductor substrate;
depositing a boundary layer on the dielectric layer such that said boundary layer is capable of preventing substantial diffusion of copper; and
depositing copper material directly on the boundary layer without any seed layer by utilizing an electrochemical deposition bath of copper ions th rough first and second applied voltage potentials such that a layer of copper is produced. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification