Doped Isolation Layer for Trench Planarization Depth Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor manufacturing lies in precisely controlling the planarization depth and maintaining structural stability of trench isolation structures, especially for high aspect ratio structures, where traditional annealing techniques can cause defects like fin bending or cracking due to thermal stress, and precise etching depth control is difficult.
Innovation Solution
Doping a foreign element into the trench isolation structure to modify its coefficient of thermal expansion (CTE), reducing structural stress, and using a predetermined concentration profile to serve as a stop signal for planarization, ensuring precise control of the planarization depth and preventing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional annealing techniques are used on trench isolation structures, then the dielectric material is properly cured and densified, but thermal stress causes fin bending or cracking
Solution Approach 1:
The patent modifies the physical-chemical parameters of the dielectric material by doping it with specific elements (such as carbon, nitrogen, or oxygen) to change its coefficient of thermal expansion. This parameter change allows the dielectric material to better match the thermal expansion characteristics of adjacent structures, reducing thermal stress during annealing processes while maintaining proper curing and densification
Solution Approach 2:
The patent directly addresses thermal expansion mismatch by selecting dopants that adjust the coefficient of thermal expansion of the dielectric material. By controlling the thermal expansion properties, the patent prevents differential expansion between the dielectric and surrounding structures during temperature cycles, thereby eliminating the root cause of thermal stress-induced defects
2Manufacturing precision
If the planarization depth is increased to fully expose fins, then all fins are properly exposed for subsequent processing, but the risk of over-etching and damaging underlying structures increases
Solution Approach 1:
The patent applies a preliminary doping action to create a distinct concentration profile of dopant elements within the dielectric material before planarization. This preliminary action establishes a measurable gradient that serves as a reference for controlling the subsequent planarization depth, allowing precise termination before reaching critical underlying structures
Solution Approach 2:
The patent implements a feedback mechanism by using the dopant concentration profile as a real-time indicator during planarization. As material is removed, the changing dopant concentration provides feedback on the etching depth, enabling dynamic adjustment of the planarization process to achieve the desired exposure without over-etching
3Ease of operation
If the trench isolation structure is fully planarized to expose all fins, then subsequent gate formation can proceed, but the structural stability of high aspect ratio structures deteriorates
Solution Approach 1:
The patent modifies the mechanical properties of the dielectric material through doping, changing parameters such as hardness, elasticity, and stress resistance. These parameter changes enhance the structural stability of high aspect ratio isolation structures, allowing them to maintain integrity during planarization and subsequent processing steps
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 reduces structural stress, prevents defects such as fin bending or cracking, and allows for precise control of the planarization depth, enhancing the stability and performance of semiconductor structures.
Implementation Method 1
The doped isolation layer has a coefficient of thermal expansion that is closer to a coefficient of thermal expansion of the fin structure than an undoped isolation layer, and thus, less structural stress is exerted on the fin structure
Implementation Method 2
doping a portion of the isolation layer with an element to form a doped isolation layer
Data Source
AI summary
A semiconductor structure with a stop layer for planarization process therein and a method for forming the same is disclosed. The method includes the steps of: forming a trench in a substrate and between active areas; filling the trench with isolation layer; doping the isolation layer with an element to form a doped isolation region; annealing the doped isolation region; and planarizing the annealed and doped isolation region and measuring a planarization depth thereof. The coefficients of thermal expansion (CTEs) of the stop layer, the dielectric layer, and the active area are different.