Semiconductor Resistor and MIM Capacitor Formation in Metal Interconnects
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Solution Overview
Problem
The existing methods for forming semiconductor resistors and capacitors in metal interconnect structures require numerous additional masking steps and often result in non-uniform capacitance values due to the roughness of metal traces, which can lead to dielectric breakdown.
Innovation Solution
A method that forms either two vertically isolated individual resistors or a metal-insulator-metal (MIM) capacitor using a semiconductor wafer with a planarized isolation structure, metallic layers, and dielectric layers, reducing the number of masking steps and improving surface smoothness to enhance capacitance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor resistors and capacitors are formed in the metal interconnect structure using conventional methods, then the devices can be integrated into the circuit, but numerous additional masking steps (four or more) are required
Solution Approach 1:
The patent combines the formation of capacitor plates with the formation of metal traces in the interconnect structure by forming both from the same conductive material layer. This merging of functions eliminates the need for separate masking steps for capacitor plate formation, reducing the total number of masking steps from four or more to just one or two, while maintaining the ability to form both resistors and capacitors in the same process flow
2Reliability
If metal traces with large grain sizes are used to form capacitor plates, then the metal interconnect structure can be formed, but the rough surface reduces dielectric distance and significantly reduces breakdown voltage
Solution Approach 1:
The patent changes the parameters of the conductive material by using a different material system - specifically, forming capacitor plates from the same metal layer used for traces but controlling the formation process to achieve smoother surfaces. This parameter change in material utilization allows maintaining structural integrity while improving surface smoothness, thereby increasing dielectric breakdown resistance without sacrificing manufacturing feasibility
Data Source
AI summary
A semiconductor structure is formed in the metal interconnect structure of an integrated circuit in a method that provides either two individual resistors that are vertically isolated from each other, or a metal-insulator-metal (MIM) capacitor. As a result, both semiconductor resistors and MIM capacitors can be formed in the same process flow.