Semiconductor Device Guard Ring Metal Bridge Prevention
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Solution Overview
Problem
The use of an un-planarized dielectric layer in semiconductor manufacturing leads to a metal bridge issue due to the rough topography, causing parasitic capacitance and narrowing the process window during photolithography and etching, resulting in metal residue formation.
Innovation Solution
Incorporating guard ring patterns made of polysilicon or polycide, which form closed loops around metal line patterns, electronically isolating metal residues and preventing them from bridging between interconnect patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an un-planarized dielectric layer is used to reduce thickness and increase parasitic capacitance, then the sustainable load feedback voltage is improved, but metal residues cause metal bridge issues that worsen manufacturing precision
Solution Approach 1:
A planarization layer is introduced as an intermediary between the un-planarized dielectric layer and the metal layer. This planarization layer provides a flat surface for accurate photolithography and etching processes while allowing the underlying dielectric layer to remain thin and un-planarized, thus maintaining the desired parasitic capacitance and feedback voltage characteristics without compromising patterning precision.
Solution Approach 2:
The dielectric structure is segmented into multiple functional layers: the un-planarized dielectric layer (providing electrical isolation and desired capacitance) and a separate planarization layer (providing a flat surface for patterning). This segmentation allows each layer to independently fulfill its specific function without interfering with the other.
2Quantity of substance
If a thicker metal layer is used to increase current capacity, then the current carrying capability is improved, but the process window narrows during photolithography and etching
Solution Approach 1:
The planarization layer serves as a mediator that decouples the metal layer thickness from the patterning process quality. By providing a flat surface, it allows thick metal layers to be patterned with the same precision as thinner layers, thus maintaining both current carrying capability and process window.
3Length of moving object
If the dielectric layer thickness is reduced to meet special requirements, then the distance between device and metal layer is improved, but planarization process cannot be performed leading to rough topography
Solution Approach 1:
The dielectric system is segmented into the thin un-planarized dielectric layer (maintaining short device-to-metal distance) and a separate planarization layer (providing flat surface). This allows the functional dielectric layer to remain thin while the planarization layer compensates for surface roughness.
Solution Approach 2:
The planarization layer acts as an intermediary surface that masks the rough topography of the thin dielectric layer, providing a flat working surface for subsequent processing while allowing the underlying dielectric to maintain its thin, un-planarized structure.
Data Source
AI summary
A semiconductor device including a plurality of doped regions, a metal layer and a polysilicon layer is provided. The doped regions are disposed in a substrate. The metal layer includes a plurality of metal line patterns. The polysilicon layer disposed between the substrate and the metal layer includes a gate pattern and at least one guard ring pattern. The at least one guard ring pattern connects to the gate pattern and surrounds at least one of the metal line patterns. One of the metal line patterns connects to the gate pattern. The others of the metal line patterns connect to one of the doped regions in the substrate.