Semiconductor Structure With STI-Protected Silicide Layout
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Solution Overview
Problem
Shallow trench isolation (STI) in semiconductor devices is susceptible to noise and leakage issues due to unselective etching processes that damage the STI structure and lead to current leakage, junction defects, and stress at the edge of the STI, affecting device performance.
Innovation Solution
A method is employed to selectively etch the dielectric layer while protecting the STI by using a photoresist mask to expose specific areas, followed by a self-aligned silicide process to form the silicide layer without damaging the STI, and using a contact etch stop layer to ensure precise etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If unselective etching process is used to remove dielectric layer, then etching speed is improved, but STI structure is damaged causing current leakage and junction defects
Solution Approach 1:
A contact etch stop layer is introduced as an intermediary between the dielectric layer and the STI structure. This stop layer is selectively etched to expose the active area while protecting the STI structure from damage during the etching process, thus maintaining both etching efficiency and STI integrity
Solution Approach 2:
The etching process is made selective to different regions: the dielectric layer is etched in active areas while the STI structure is protected in isolation regions. This local selectivity allows fast etching where needed while preserving STI structure where isolation is required
2Reliability
If photoresist mask is used to protect STI during etching, then STI damage is reduced, but process complexity increases
Solution Approach 1:
The contact etch stop layer performs dual functions: it serves as a protective layer during etching and automatically defines the etch boundary through its selective etch characteristics. The layer 'self-regulates' the etching process by being etched only in desired areas, eliminating the need for complex photoresist masking patterns
3Manufacturing precision
If self-aligned silicide process is used to form silicide layer, then alignment precision is improved, but process time increases
Solution Approach 1:
The contact etch stop layer is formed in advance with pre-defined patterns that guide subsequent etching and silicide formation steps. This preliminary structuring enables self-alignment in later processes, achieving high precision without requiring multiple alignment steps or extended process times
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 minimizes damage to the STI, reduces junction leakage, and enhances device reliability by maintaining electrical isolation and improving flicker noise characteristics.
Implementation Method 1
using a photoresist mask to expose specific areas
Implementation Method 2
followed by a self-aligned silicide process to form the silicide layer without damaging the STI
Implementation Method 3
using a contact etch stop layer to ensure precise etching
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate and an insulation region within the substrate. The insulation region defines an active area in the substrate, with the active area extending along a first direction. A gate structure is formed across the active area and extends along a second direction perpendicular to the first direction. A first dielectric layer is disposed over a portion of the active area, the insulation region, and a portion of the gate structure. The first dielectric layer continuously extends along the first direction from one end of the active area to the other end. A silicide region is formed over the exposed portions of the active area and the gate structure, wherein the silicide region is free from separated subregions from a top view perspective. A second dielectric layer is formed over and in contact with the first dielectric layer.