Insulative Island Trench Patterning for Semiconductor Reliability
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is the difficulty in precisely patterning metal layers, leading to over-etching issues during the formation of trenches in the damascene process, which can damage the conductive structures and affect the reliability of the wiring structures.
Innovation Solution
A method involving the use of a first mask to form a first trench and a second mask with reduced thickness in the overlapping region to form a second trench, which prevents over-etching by creating a fluid communication between the trenches and forming a conductive pattern within them, using an etch stop layer and insulation patterns to control the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is used to form wiring structures, then electrical resistance in the wiring structure is reduced, but it becomes difficult to pattern the metal layer with high precision
Solution Approach 1:
The patent divides the single trench formation process into two sequential steps: first forming a preliminary trench with a first mask, then forming a final trench with a second mask. This segmentation allows each etching step to be controlled independently, improving overall patterning precision while maintaining the low electrical resistance benefits of metal wiring structures.
Solution Approach 2:
The first mask and preliminary trench formation serve as a preliminary action that prepares the structure for the final precise patterning. By pre-defining the trench location and removing insulation patterns in advance, the second etching step can focus on achieving high precision without the complexity of forming the entire structure in one step.
2Manufacturing precision
If trenches are formed using a damascene process, then wiring structures can be formed with improved patterning, but over-etching may occur during the process
Solution Approach 1:
The etching process is segmented into two distinct steps with separate masks. The first etching step removes insulation patterns with a first mask, and the second etching step forms the final trench with a second mask. This segmentation prevents over-etching by limiting each etching step's exposure time and allowing selective removal of only the intended materials.
Solution Approach 2:
The patent applies different mask structures at different locations: the first mask covers areas where insulation patterns should be removed, while the second mask is positioned to define the final trench boundaries. This local differentiation ensures that etching occurs only where intended, preventing over-etching while maintaining patterning precision.
3Reliability
If the mask layer is made thinner in the overlapping region, then over-etching is prevented, but the mask structure becomes more complex
Solution Approach 1:
The mask system is segmented into two separate masks with distinct functions and thickness profiles. The first mask has uniform thickness for initial patterning, while the second mask has reduced thickness in overlapping regions to prevent over-etching. This segmentation manages complexity by distributing different requirements to different mask components rather than attempting to satisfy all requirements in a single mask.
Solution Approach 2:
The second mask is designed with spatially varying thickness: thicker in regions where full coverage is needed and thinner in overlapping regions where over-etching prevention is critical. This local quality adjustment optimizes the mask structure's performance by applying different thickness characteristics to different locations based on their specific functional requirements.
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 approach enhances the reliability of semiconductor devices by reducing over-etching and ensuring precise alignment and communication between trenches, thereby improving the integrity of the conductive patterns and reducing electrical resistance.
Implementation Method 1
The insulating layer is etched to form a second trench using the mask as an etching mask
Data Source
AI summary
A semiconductor device and methods of forming a semiconductor device are disclosed. In the methods, a layer, such as an insulating interlayer, is formed on a substrate. A first trench is formed in the layer, and a mask layer is formed in the first trench. The mask layer has a first thickness from a bottom surface of the first trench to the top of the mask layer. The mask layer is patterned to form a mask that at least partially exposes a sidewall of the first trench. A portion of the mask adjacent to the exposed sidewall of the first trench has a second thickness smaller than the first thickness. The layer is etched to form a second trench using the mask as an etching mask. The second trench is in fluid communication with the first trench. A conductive pattern is formed in the first trench and the second trench.