Mandrel Layer Structure for Semiconductor Trench Formation
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Solution Overview
Problem
As semiconductor technology advances towards smaller process nodes, the challenge of improving pattern transfer accuracy and expanding the process window for pattern transfer becomes increasingly difficult due to the shrinking technology nodes, leading to reduced precision and complexity in IC manufacturing.
Innovation Solution
A semiconductor structure and formation method involving a base with a first mandrel layer and a first mask layer, where a second mandrel layer fills openings in the first mask layer, and side wall layers are formed on trenches to isolate second trenches from first trenches, allowing for the retention of the first mandrel layer below the mask layer, thereby enhancing the process window and accuracy of pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mask-based methods are used to define trench positions, then the process can be completed with standard steps, but the process window for pattern transfer is narrow and accuracy deteriorates as technology nodes shrink
Solution Approach 1:
The patent divides the mandrel structure into multiple layers (first mandrel layer and second mandrel layer) with the first mask layer positioned between them. This segmentation allows independent formation and protection of each layer, enabling precise pattern transfer while maintaining process feasibility. The first mandrel layer serves as the primary pattern definition, while the second mandrel layer provides additional structural support and protection during etching operations.
Solution Approach 2:
The first mask layer is formed and positioned on the first mandrel layer before the second mandrel layer is deposited. This preliminary action establishes the pattern definition early in the process, allowing subsequent steps to proceed with protected precision. The mask layer acts as a preliminary protective barrier that guides the formation of trenches while preventing damage to the underlying mandrel structure.
2Manufacturing precision
If the first mandrel layer is removed completely after forming openings, then the structure is simplified, but the process window for forming second trenches is reduced and accuracy is compromised
Solution Approach 1:
The first mask layer is retained on the first mandrel layer during the formation of the second mandrel layer and subsequent etching steps. This retained mask layer acts as a cushioning protective layer that prevents direct exposure and potential damage to the first mandrel layer during aggressive etching operations. The mask layer absorbs process variability and protects the critical pattern definition features throughout the manufacturing sequence.
Solution Approach 2:
The first mask layer serves as an intermediary protective element between the etching process and the first mandrel layer. It mediates the interaction by providing a sacrificial barrier that can be selectively removed or retained depending on process requirements, thereby protecting the underlying mandrel structure while allowing controlled access where needed for pattern transfer.
3Productivity
If technology nodes are continuously shrunk to increase functional density, then more circuits can be integrated, but the process window for pattern transfer becomes narrower and manufacturing becomes more difficult
Solution Approach 1:
The patent transitions from a conventional single-layer mandrel approach to a multi-layer vertical structure with the first mandrel layer, first mask layer, and second mandrel layer stacked in sequence. This dimensional change from two-dimensional planar processing to three-dimensional layered architecture provides additional process windows and control parameters, allowing precise pattern transfer even at shrunk technology nodes by utilizing vertical layering rather than relying solely on lateral resolution.
Data Source
AI summary
A semiconductor structure and a formation method thereof are disclosed. The formation method includes: providing a base, wherein a first mandrel layer and a first mask layer located on the first mandrel layer are formed on the base, and openings exposing the first mandrel layer are formed in the first mask layer; forming a second mandrel layer covering the first mask layer, wherein the second mandrel layer also fills the openings; forming first trenches running through the second mandrel layer, the first mask layer and the first mandrel layer, wherein the side walls of the first trenches expose the second mandrel layer in the openings; forming side wall layers on the side walls of the first trenches; and etching to remove the second mandrel layer and the first mandrel layer below the positions of the openings by taking the side wall layers as masks to form second trenches running through the first mandrel layer, wherein the second trenches and the first trenches are isolated by the side wall layers. The present disclosure enlarges a process window for forming the second trenches under the protective effect of the first mask layer.