Semiconductor Seal Ring Layout With Transition Region for CMP Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seal ring structures in semiconductor wafers face processing issues due to property differences between the seal ring region and the circuit region, leading to problems such as dishing in chemical mechanical planarization (CMP) processes and over etching in etching processes.
Innovation Solution
A seal ring structure with a transition region designed to buffer the differences in properties between the seal ring and circuit regions, featuring concentric seal rings, transition lines, and corner regions with specific line widths, pitches, and pattern densities to provide a smooth transition and alleviate processing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal ring structure is formed around circuit dies to protect circuits, then protection from moisture degradation and ionic contamination is improved, but processing issues such as dishing in CMP processes and over etching in etching processes occur due to property differences between seal ring region and circuit region
Solution Approach 1:
A transition region is introduced as an intermediary between the seal ring region and the circuit region. This transition region contains conductive lines with intermediate pattern densities that bridge the property gap between the high-pattern-density seal ring region and the low-pattern-density circuit region, thereby preventing dishing and over etching while maintaining protection functionality
Solution Approach 2:
The seal ring structure is divided into distinct regions with different local properties: the seal ring region with high pattern density for protection, the transition region with intermediate pattern density to buffer property differences, and the circuit region with low pattern density for device functionality. Each region is optimized for its specific function
2Reliability
If concentric seal rings are formed to enclose circuit regions, then sealing effectiveness is improved, but pattern density differences between seal ring region and circuit region cause dishing in subsequent CMP processes
Solution Approach 1:
The transition region acts as a mediator between the concentric seal rings and the circuit region, providing a gradual transition in pattern density that prevents the abrupt property changes causing dishing during CMP processes
Solution Approach 2:
The solution extends the structure into the vertical dimension by forming the transition region as an intermediate layer between the seal ring region and circuit region, creating a three-dimensional gradient structure that smooths property transitions
3Reliability
If seal ring region has high pattern density compared to circuit region, then sealing function is achieved, but over etching occurs in subsequent etching processes
Solution Approach 1:
The transition region is designed with intermediate local pattern density properties that are higher than the circuit region but lower than the seal ring region, creating a gradient that prevents over etching while maintaining sealing function
Solution Approach 2:
The pattern density parameter is gradually changed across the transition region, creating a continuous gradient from the high pattern density of the seal ring region to the low pattern density of the circuit region, thereby preventing abrupt etching rate changes
Data Source
AI summary
A semiconductor structure includes a substrate; a seal ring region around a circuit region over the substrate, wherein the seal ring region includes a sealing region and a transition region, and wherein the transition region is disposed between the sealing region and the circuit region; and a stack of metal layers disposed over the circuit region, the transition region and the sealing region. A metal layer of the stack of metal layers includes metal seal rings disposed in the sealing region including a first section along a first direction and a second section along a second direction, wherein the second direction is substantially perpendicular to the first direction; and metal transition lines disposed in the transition region along the first section and the second section, wherein the metal transition lines are oriented lengthwise along the first direction.