Semiconductor Storage Via Contact Melting Prevention
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Solution Overview
Problem
The existing semiconductor storage devices with three-dimensional memory cell arrays face issues with via contacts melting due to concentrated current flow from the source layer to the upper wiring, which can lead to structural failures and reduced device reliability.
Innovation Solution
The semiconductor storage device design includes a configuration with multiple via contacts between the local wiring and upper wiring, utilizing low resistance metals like tungsten, and additional wiring layers (M0_1 and M0_2) to distribute the current, preventing excessive heat generation and melting of via contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single via contact is used to connect local wiring to upper wiring, then the structure is simple and manufacturing is easier, but the current concentrates on the via contact which may melt it
Solution Approach 1:
The patent divides the single via contact into multiple via contacts (first via contact and second via contact) to distribute the current flow. This segmentation reduces the current density on each individual via contact, preventing melting while maintaining manufacturing feasibility through standard multi-patterning techniques.
Solution Approach 2:
The patent introduces an additional wiring layer (second wiring) above the first wiring to create a three-dimensional current distribution path. This dimensional expansion allows current to flow through multiple parallel paths (via contacts and wiring segments) rather than concentrating through a single via contact, effectively solving the melting problem.
2Reliability
If multiple via contacts are used to distribute current, then via contact melting is prevented, but the device complexity increases
Solution Approach 1:
The patent combines the via contacts with the existing wiring layers in an integrated manner. The first and second wirings are formed as continuous conductive structures that naturally incorporate the via contacts as connection points, rather than treating via contacts as separate additional elements. This merging approach reduces overall structural complexity.
Solution Approach 2:
The first wiring serves multiple functions: it acts as a current distribution path, provides structural support, and serves as a connection layer for both via contacts. The second wiring similarly provides both current path functionality and structural integrity. This multi-functionality reduces the need for additional specialized structures.
3Stability of the object's composition
If low resistance metal like tungsten is used in local wiring, then warpage is prevented and formation is concurrent with contacts, but current concentration still occurs at via contacts
Solution Approach 1:
The patent segments the current path at the via contact interface by creating multiple parallel via contacts (first and second via contacts) connecting the low resistance metal local wiring to the upper wiring. This segmentation distributes the current that would otherwise concentrate in a single via, preventing melting while preserving the warpage prevention benefits of the low resistance metal.
Solution Approach 2:
The first wiring acts as an intermediary conductive layer between the low resistance metal local wiring and the upper wiring. It receives current from multiple via contacts and distributes it further, mediating the current flow to prevent concentration at any single via contact interface while maintaining the overall low resistance path.
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 configuration effectively disperses the source current, reducing the risk of via contact melting and enhancing the reliability and longevity of the semiconductor storage device by maintaining low resistance connections.
Implementation Method 1
a local wiring that connects a source layer provided below the memory cell array to an upper wiring is provided in a tap area
Implementation Method 2
The current concentrates on the via contact between the local wiring and the upper wiring, which may melt the via contact
Data Source
AI summary
A semiconductor storage device includes a memory cell array including a stacked body having insulating layers and conductive layers that are alternately stacked. The memory cell array includes a cell area and a contact area provided adjacent the cell area. The semiconductor storage device includes: a circuit below the memory cell array; a source layer between the memory cell array and the circuit; a first contact in the contact area, and coupled to the circuit; a second contact over the cell area and the contact area; a first wiring extending in a direction intersecting an extending direction of the second contact in the contact area; a second wiring above the second contact, extending along the second contact in the contact area, and connected to the first wiring; and third contacts between the second wiring and the second contact.