Complementary BEOL Capacitor Merging MOM and MIM Structures
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Solution Overview
Problem
It becomes increasingly challenging to fabricate high-density capacitance in integrated circuits using only metal oxide metal (MOM) capacitors, and existing metal insulator metal (MIM) capacitors require additional masks and a high-K oxide deposition process to achieve increased capacitor density.
Innovation Solution
A complementary back end of line (BEOL) capacitor structure that combines a metal oxide metal (MOM) capacitor with one or more metal insulator metal (MIM) capacitors from different conductive interconnect layers, leveraging lateral coupling of MOM capacitors and vertical coupling of MIM capacitors to enhance capacitance density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only MOM capacitors are used in lower conductive interconnect layers, then lateral coupling provides improved matching characteristics, but capacitance density becomes insufficient for future high-density requirements
Solution Approach 1:
The patent combines MOM capacitor structure (using lateral coupling between conductive fingers in lower interconnect layers) with MIM capacitor structure (using vertical coupling between metal plates separated by insulator) to create a hybrid capacitor that achieves both improved matching characteristics and high capacitance density. The MOM portion provides the lateral coupling benefits while the MIM portion adds vertical capacitance stacking capability.
Solution Approach 2:
The patent transitions from purely lateral coupling in MOM capacitors to include vertical coupling dimension by integrating MIM capacitor structure. This adds the vertical dimension (stacking metal plates with insulator layers between them) to the traditional lateral arrangement, enabling higher capacitance density through three-dimensional space utilization.
2Quantity of substance
If MIM capacitors are used to achieve increased capacitor density, then vertical plate to plate coupling provides higher density, but additional masks and high-K oxide deposition processes are required
Solution Approach 1:
The patent merges the fabrication processes of MOM and MIM capacitors into a unified hybrid structure. By integrating both capacitor types in a single device, the patent leverages existing process steps for both MOM (lateral finger coupling) and MIM (vertical plate coupling) rather than requiring completely separate fabrication sequences, thereby reducing overall process complexity.
Solution Approach 2:
The hybrid capacitor structure serves multiple functions: it provides both lateral coupling (MOM) and vertical coupling (MIM) capabilities within a single device. This multi-functionality allows the capacitor to achieve high density while utilizing standard interconnect layer structures that are already present in the semiconductor device, avoiding the need for entirely new fabrication processes.
3Quantity of substance
If MOM capacitors are formed in lower conductive interconnect layers with smaller dimensions, then capacitance density increases, but interconnect widths and spaces become increasingly difficult to fabricate
Solution Approach 1:
The patent resolves the fabrication difficulty by adding the vertical dimension through MIM capacitor integration. Instead of continuously shrinking lateral dimensions in lower interconnect layers, the solution stacks capacitor structures vertically using upper interconnect layers, thereby achieving higher capacitance density without further reducing already minimal lateral dimensions.
Solution Approach 2:
The patent segments the capacitor structure into distinct MOM and MIM portions, each optimized for different functions. The MOM portion utilizes lower interconnect layers for lateral coupling with improved matching, while the MIM portion uses upper interconnect layers for vertical coupling with high density, thereby distributing the design challenges across different structural segments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The combined structure increases capacitance density by integrating the lateral coupling of MOM capacitors with the vertical coupling of MIM capacitors, simplifying the fabrication process and avoiding additional deposition and mask requirements for MIM capacitors.
Implementation Method 1
The MOM capacitors 130 make use of a lateral (intra layer) capacitive coupling 140 between fingers formed by standard metallization of the conductive interconnects
Implementation Method 2
The MIM capacitor uses vertical plate to plate coupling. This solution, however, involves additional masks as well as a high-K (HiK) oxide deposition process to achieve an increased capacitor density
Implementation Method 3
An dielectric (not shown) is provided between the conductive fingers
Data Source
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AI summary
A complementary back end of line (BEOL) capacitor (CBC) structure includes a metal oxide metal (MOM) capacitor structure. The MOM capacitor structure is coupled to a first upper interconnect layer of an interconnect stack of an integrated circuit (IC) device. The MOM capacitor structure includes at least one lower interconnect layer of the interconnect stack. The CBC structure may also include a second upper interconnect layer of the interconnect stack coupled to the MOM capacitor structure. The CBC structure also includes at least one metal insulator metal (MIM) capacitor layer between the first upper interconnect layer and the second upper interconnect layer. In addition, CBC structure may also include a MIM capacitor structure coupled to the MOM capacitor structure. The MIM capacitor structure includes a first capacitor plate having a portion of the first upper interconnect layer, and a second capacitor plate having a portion of the MIM capacitor layer(s).