Self-Aligned Gate Cut Structures for Precise Fin Isolation
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Solution Overview
Problem
The challenge of aligning gate cut structures in semiconductor devices accurately is difficult due to alignment errors in lithography, leading to yield loss and device variability, which can cause timing errors and failures.
Innovation Solution
The formation of self-aligned gate cut structures is achieved by using spacer structures on the sidewalls of adjacent semiconductor fins, filled with a sacrificial material that is etch selective, allowing for precise placement of the gate cut structures before the gate is patterned, ensuring equal distance and isolation between adjacent devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography alignment methods are used to form gate cut structures, then the manufacturing process is simple, but the alignment precision deteriorates leading to errors greater than 1 nm
Solution Approach 1:
The gate cut structures are formed in advance before the gate pattern is formed. Spacer structures are first created on sidewalls of semiconductor fins, then gate cut structures are formed between adjacent fins using these spacers as alignment references. This preliminary formation ensures that when the gate pattern is later formed, the gate cut structures are already precisely positioned, achieving sub-1 nm alignment precision without relying on subsequent lithography alignment steps.
Solution Approach 2:
Spacer structures serve as intermediary elements that mediate between the semiconductor fins and the gate cut structures. These spacers are formed on the sidewalls of adjacent fins and provide a physical reference that enables precise positioning of gate cut structures. The spacers act as a bridge that transfers the fin geometry information to the gate cut structure formation process, ensuring accurate alignment.
2Productivity
If gate cut structures are formed after gate patterning, then the process sequence is simplified, but alignment errors increase leading to yield loss
Solution Approach 1:
Gate cut structures are formed in advance before gate patterning occurs. This resequencing of operations allows the gate cut structures to be established using the semiconductor fin geometry as a reference, ensuring precise alignment. By performing this action preliminarily, the patent avoids subsequent alignment operations that would otherwise be required, thereby improving yield without significant time penalty.
Solution Approach 2:
The gate cut structures self-align to the semiconductor fins through the spacer structures. The spacers are formed directly on the fin sidewalls, and the gate cut structures are subsequently formed between adjacent fins using these spacers as automatic alignment references. This self-aligning mechanism eliminates the need for separate alignment operations and lithography steps, improving both yield and process efficiency.
3Reliability
If alignment tolerance is relaxed to simplify manufacturing, then device variability increases causing timing errors and failures
Solution Approach 1:
Spacer structures act as intermediary elements that ensure precise and consistent placement of gate cut structures relative to semiconductor fins. These spacers are formed conformally on the fin sidewalls, providing a uniform reference distance that is transferred to the gate cut structure formation. This intermediary mechanism guarantees sub-1 nm placement precision, ensuring that gate cut structures are consistently positioned at the correct location, thereby maintaining device timing consistency and reliability.
Solution Approach 2:
The patent changes the formation timing parameter of gate cut structures, forming them before gate patterning instead of after. This parameter change in the process sequence allows the gate cut structures to be formed when the semiconductor fin geometry is already established and can serve as a precise reference. This parameter change ensures placement precision within 1 nm, preventing device variability and timing errors.
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
This method ensures consistent alignment of gate cut structures within 1 nm of each other, providing enhanced isolation and reducing the risk of shorting, thus improving device reliability and yield.
Implementation Method 1
filled with a sacrificial material that is etch selective, allowing for precise placement of the gate cut structures before the gate is patterned
Data Source
AI summary
Techniques are provided herein to form semiconductor devices having self-aligned gate cut structures. 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. A gate cut structure that includes a dielectric material interrupts the gate structure between the neighboring semiconductor devices. Due to the process of forming the gate cut structure, the distance between the gate cut structure and the semiconductor region of one of the neighboring semiconductor devices is substantially the same as (e.g., within 1.5 nm of) the distance between the gate cut structure and the semiconductor region of the other one of the neighboring semiconductor devices and the gate cut structure extends beyond the width of the gate structure to also interrupt gate spacers on the sidewalls of the gate structure.