Shallow Trench Isolation Liner Oxide Thickness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The shallow trench isolation process in semiconductor device manufacturing faces defects such as dishing and damage to the nitride layer due to thickness differences in the deposition of insulating layers between dense and isolation areas, leading to inefficiencies in chemical mechanical planarization.
Innovation Solution
By reducing the thickness of the liner oxide layer on the bottom of trenches in isolation areas, the deposition rate of the filling oxide layer is increased, reducing thickness differences and alleviating defects through controlled etching and planarization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conformal deposition process is used to form the filling oxide layer, then the insulating layer is deposited uniformly on the sidewalls of trenches, but the thickness of the oxide layer in isolation areas becomes significantly less than in dense areas, causing dishing defects and potential damage to the nitride layer during planarization
Solution Approach 1:
The patent applies local quality by forming a thicker liner oxide layer specifically in isolation areas where the trench width is greater than or equal to 1 μm, while maintaining a standard thickness in dense areas. This localized modification compensates for the conformal deposition characteristic, ensuring that after planarization, both isolation and dense areas achieve the desired flatness without dishing defects or nitride layer damage.
2Ease of operation
If a chemical mechanical planarization process is used to planarize the filling oxide layer, then the surface is flattened, but the oxide layer in isolation areas is more easily removed than in dense areas due to thickness differences, causing apparent dishing defects
Solution Approach 1:
The patent implements preliminary action by pre-adjusting the liner oxide layer thickness in isolation areas before the conformal deposition of the filling oxide layer. This preparatory step ensures that when planarization is performed, the thickness differences between isolation and dense areas are minimized, thereby reducing dishing defects and eliminating the need for aggressive planarization that could damage the nitride layer.
3Reliability
If the removal amount in the chemical mechanical planarization process is reduced to avoid dishing defects, then the nitride layer is protected from damage, but part of the deposited insulating layer on the device surface remains uncleared
Solution Approach 1:
The patent applies local quality by differentiating the liner oxide layer thickness based on location: thicker in isolation areas and standard in dense areas. This spatial variation allows the planarization process to be more aggressive overall without damaging the nitride layer in dense areas, as the thicker liner in isolation areas compensates for the additional removal, thereby clearing the device surface effectively while maintaining nitride layer integrity.
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 ensures consistent thickness of the filling oxide layer across both dense and isolation areas, minimizing defects and enhancing the planarization process, resulting in improved semiconductor device quality.
Implementation Method 1
the filling oxide outside the surface of the trenches is planarized through a chemical mechanical planarization process
Implementation Method 2
a second insulating layer such as a filling oxide layer 106 is deposited in the trenches by means of, for example, a high aspect ratio process (HARP)
Data Source
AI summary
A semiconductor device and a manufacturing method therefor is based on the fact that a thinner liner oxide layer on the bottom of the trenches can lead to a higher subsequent deposition rate. After forming trenches and a liner oxide layer and before depositing a filling oxide layer in the trenches, a portion of or all of the thickness of the liner oxide layer on bottom of trenches in an isolation area is removed. Removing some or all of a liner oxide layer on the bottom of trenches in an isolation area can improve the deposition rate for trenches in such that the difference in thickness can be reduced for deposited filling oxide layer between isolation area and dense area.