Gate Cut Grating Layout for Self-Aligned IC Device Isolation
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Solution Overview
Problem
The challenge in integrated circuit fabrication lies in forming high-density semiconductor devices with tight alignment tolerances, which often results in reduced yield and potential failure due to complex lithography processes and alignment issues, particularly in forming gate cut structures between adjacent semiconductor devices.
Innovation Solution
The technique involves creating a grating pattern of gate cut structures across an integrated circuit using a single lithographic mask and etching process, with self-assembled polymer materials for self-aligned conductive gate bridges, allowing for simultaneous formation of dielectric walls between adjacent devices and reducing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional gate cut structures are formed between adjacent semiconductor devices, then device isolation is achieved, but alignment accuracy deteriorates due to complex lithography processes and tight alignment tolerances
Solution Approach 1:
The patent introduces an intermediary grating structure that serves as a mediator between the lithography process and the final gate cut structures. This grating acts as a template that simplifies the lithography step while ensuring precise alignment of multiple gate cuts, thereby resolving the contradiction between achieving proper device isolation and maintaining alignment accuracy.
Solution Approach 2:
The patent segments the gate cut formation process into two distinct stages: first forming a grating structure that defines the positions of multiple gate cuts, then using this grating as a template for subsequent etching. This segmentation allows the complex alignment task to be broken down into simpler, more manageable steps, improving both device isolation and alignment accuracy.
2Reliability
If multiple masking processes are used to form gate cut structures, then complete device isolation is achieved, but manufacturing complexity increases leading to reduced yield
Solution Approach 1:
The patent merges multiple masking processes into a single lithography step by forming a grating structure that simultaneously defines the positions of multiple gate cuts. This consolidation reduces the number of separate masking and etching operations required, thereby simplifying the manufacturing process while maintaining complete device isolation between adjacent semiconductor devices.
Solution Approach 2:
The grating structure serves multiple functions: it acts as a lithography template for defining gate cut positions, serves as an alignment reference for subsequent processing steps, and provides a physical mask during etching. This multi-functionality eliminates the need for separate masking processes, reducing manufacturing complexity while ensuring reliable device isolation.
3Manufacturing precision
If tighter alignment tolerances are imposed to improve gate cut precision, then manufacturing precision improves, but device complexity and process difficulty increase
Solution Approach 1:
The patent performs preliminary action by forming the grating structure before the actual gate cut etching. This grating is created with relaxed alignment tolerances using standard lithography, and then serves as a pre-positioned template that guides subsequent self-aligned etching processes. This preliminary structuring achieves high gate cut precision without imposing tight alignment tolerances on the main lithography step, thereby reducing process difficulty.
Solution Approach 2:
The grating structure serves itself as a alignment reference and mask for the subsequent gate cut formation. The etching process uses the grating's own physical structure to define the cut positions, eliminating the need for external alignment marks or complex photolithography alignment procedures. This self-service mechanism achieves high precision while simplifying the overall process.
Data Source
AI summary
Techniques are provided herein to form an integrated circuit having a grating pattern of gate cut structures such that a gate cut structure extends between the gate layers of adjacent semiconductor devices and between the source or drain regions (e.g., epitaxial regions) of the adjacent semiconductor devices. In an example, neighboring semiconductor devices each include a semiconductor region extending between a source region and a drain region, and a gate structure extending over the semiconductor regions of the neighboring semiconductor devices. In some such examples, a gate cut structure is present between each pair of neighboring semiconductor devices thus interrupting the gate structure and isolating the gate electrode of one semiconductor device from the gate electrode of the other semiconductor device. The gate cut structure further extends to separate the source or drain regions of the neighboring semiconductor devices. Subsequent processes allow neighboring gate or source or drain regions connections.