COAG Gate Contacts Using DSA for Sub-10 nm Alignment
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Solution Overview
Problem
The scaling of multi-gate transistors to smaller dimensions and increased densities poses significant challenges due to variability in conventional fabrication processes, making it difficult to extend these processes to the 10 nanometer node or sub-10 nanometer node range.
Innovation Solution
The implementation of contact over active gate (COAG) structures using directed self-assembly (DSA) allows for the formation of gate contact structures over active portions of gate electrodes, enabling self-aligned gate contacts and interconnects. This approach simplifies the front-end-of-line (FEOL) process by shortening the required FE stack, reducing the complexity of etches and depositions, and enabling metal gate cuts and cell height reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used for scaling, then existing process infrastructure can be maintained, but manufacturing precision and reliability deteriorate at 10 nanometer node and smaller
Solution Approach 1:
The patent employs self-aligned contact formation where the gate contact structure automatically positions itself relative to the gate electrode through the FEOL process integration, eliminating the need for separate lithographic alignment steps. This self-alignment mechanism inherently compensates for variability and achieves the required sub-10 nanometer precision without relying on conventional multi-step alignment processes.
Solution Approach 2:
The patent implements preliminary formation of the gate contact structure during the FEOL process before subsequent interconnect layers are deposited. By establishing the contact position and structure early in the fabrication sequence, the design rules are simplified and precision is maintained through the self-aligned nature of the preliminary structure formation.
2Manufacturing precision
If additional lithographic steps are used for contact formation, then manufacturing precision can be maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the gate contact formation process with the existing FEOL fabrication sequence, combining what would traditionally be separate lithographic and etching steps into an integrated self-aligned process. This consolidation eliminates additional lithographic steps while maintaining precision through the self-aligned mechanism inherent in the merged process flow.
Solution Approach 2:
The gate contact structure serves multiple functions: it provides electrical connection to the gate electrode, establishes alignment references for subsequent layers, and simplifies design rules. This multi-functionality is achieved through the self-aligned formation process that creates a universal structure serving both contact and alignment purposes without requiring additional specialized steps.
3Area of stationary object
If standard cell area is reduced for scaling, then area efficiency improves, but manufacturing precision requirements become more stringent
Solution Approach 1:
The self-aligned contact formation mechanism automatically maintains precision as cell dimensions are reduced, because the alignment is determined by the physical structure formation rather than by lithographic registration. This self-service alignment mechanism scales down with the feature size without requiring proportionally tighter process control, enabling area reduction while maintaining manufacturing precision.
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 COAG structures using DSA facilitate a more robust and controlled FEOL process, reducing standard cell area requirements and improving area scaling by allowing direct contact formation on active gate regions without the need for additional lithographic steps or complex stack recessing.
Implementation Method 1
contact over active gate (COAG) structures using directed self-assembly (DSA)
Data Source
AI summary
Contact over active gate (COAG) structures are described. In an example, an integrated circuit structure includes a plurality of gate structures above substrate, each of the gate structures including a gate insulating layer thereon. A plurality of conductive trench contact structures is alternating with the plurality of gate structures, each of the conductive trench contact structures including a trench insulating layer thereon. A remnant of a di-block-co-polymer is over a portion of the plurality of gate structures or the plurality of conductive trench contact structures. An interlayer dielectric material is over the di-block-co-polymer, over the plurality of gate structures, and over the plurality of conductive trench contact structures. An opening in the interlayer dielectric material. A conductive structure is in the opening, the conductive structure in direct contact with a corresponding one of the trench contact structures or with a corresponding one of the gate contact structures.