MIM Capacitor Fabrication Using Gate Metal Electrodes
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Solution Overview
Problem
The fabrication of metal-insulator-metal (MIM) capacitors in semiconductor dies during back-end-of-line (BEOL) processing requires multiple process steps and masks, increasing manufacturing costs and making it difficult to control capacitance effectively.
Innovation Solution
A method for fabricating MIM capacitors using gate metal for electrodes and a high-k gate dielectric material, which allows for concurrent formation with N-channel and P-channel field effect transistor (NFET and PFET) gate stacks without additional masks, leveraging existing high-k metal gate processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized dielectric and metal layers are inserted during BEOL processing to form MIM capacitor electrodes, then MIM capacitor functionality is achieved, but manufacturing cost increases due to multiple process steps and masks
Solution Approach 1:
The patent merges the MIM capacitor formation process with the existing high-k metal gate transistor fabrication process. The gate metal layers and high-k dielectric layers that form transistor gates are simultaneously used to form MIM capacitor electrodes and dielectric, eliminating the need for separate specialized layers and reducing manufacturing steps
Solution Approach 2:
The high-k metal gate layers serve dual purposes: forming the transistor gate structure and creating the MIM capacitor electrodes and dielectric. This multi-functional use of existing layers eliminates the need for additional specialized materials and process steps
2Reliability
If conventional BEOL processing is used to insert specialized layers for MIM capacitors, then capacitor electrodes and dielectric are formed, but capacitance control becomes difficult
Solution Approach 1:
The patent controls capacitance by adjusting parameters of existing high-k metal gate layers, such as layer thickness, material composition, and stacking configuration. These parameter changes enable precise capacitance control without introducing additional process complexity
3Manufacturing precision
If multiple process steps and masks are used during BEOL processing to form MIM capacitors, then specialized dielectric and metal layers are deposited, but manufacturing cost and process time increase
Solution Approach 1:
The high-k metal gate layers are deposited and patterned before final transistor gate formation. This preliminary action allows the same layers to be used for both transistor gates and MIM capacitors, eliminating subsequent specialized deposition steps and improving manufacturing efficiency
Data Source
AI summary
According to one exemplary embodiment, a method for fabricating a MIM capacitor in a semiconductor die includes forming a dielectric one segment over a substrate and a metal one segment over the dielectric one segment, where the metal one segment forms a lower electrode of the MIM capacitor. The method further includes forming a dielectric two segment over the dielectric one segment and a metal two segment over the dielectric two segment, where a portion of the metal two segment forms an upper electrode of the MIM capacitor. The metal one segment comprises a first gate metal. The metal two segment can comprise a second gate metal.