Cylindrical Capacitor Guard Ring Gapfill Film
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Solution Overview
Problem
Conventional semiconductor fabrication techniques face challenges in forming stable cylindrical capacitors with high capacitance within sub-50 nm design rules, leading to potential cracking and bunker defects due to stress from thick interlayer dielectrics and weak guard rings, which can result in storage node oxide damage and short circuits.
Innovation Solution
A method is introduced to fabricate a semiconductor device with a cylindrical type capacitor by filling the guard ring with a gapfill film that has selectivity against wet etchants, protecting the storage node oxide and preventing defects by ensuring a stable guard ring structure, involving steps like depositing storage node oxides, forming conductive layers, and using specific materials and processes for capping and gapfill films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of cylindrical capacitor is increased to ensure desired capacitance, then capacitance is improved, but step difference between cell region and peripheral region increases requiring thicker interlayer dielectric which makes capacitor prone to cracking
Solution Approach 1:
The patent performs preliminary planarization by removing storage node oxide from peripheral regions before forming the interlayer dielectric. This preliminary action eliminates the need for thick interlayer dielectric to compensate for step differences, thereby preventing capacitor cracking while maintaining desired capacitance through controlled capacitor height
2Reliability
If guard ring is formed at boundary of peripheral region to protect storage node oxide during dip-out process, then storage node oxide protection is improved, but guard ring structure becomes weak leading to cracks and lifting at interface
Solution Approach 1:
The patent performs preliminary removal of storage node oxide from peripheral regions before forming the guard ring structure. This preliminary action allows the guard ring to be formed on a planarized surface, eliminating weak points and interface lifting issues while maintaining its protective function against etchant penetration
Solution Approach 2:
The patent changes the structural parameters of the guard ring by forming it with optimized dimensions and material composition after preliminary planarization. This parameter optimization strengthens the guard ring structure, preventing cracks and interface lifting while maintaining its protective barrier function
3Manufacturing precision
If wet dip-out process is used to remove storage node oxide in cell region, then manufacturing precision is improved, but etchant permeates through weak guard ring causing bunker defects
Solution Approach 1:
The patent performs preliminary planarization by removing storage node oxide from peripheral regions before the wet dip-out process. This preliminary action creates a robust guard ring structure that effectively blocks etchant penetration, preventing bunker defects while maintaining the precision benefits of wet dip-out for capacitor formation
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 prevents bunker defects and damage to the storage node oxide, ensuring a stable cylindrical capacitor structure and reducing semiconductor device failures, thereby enhancing yield and quality.
Implementation Method 1
filling the guard ring with a gapfill film that has a selectivity against the wet etchant
Implementation Method 2
performing a wet dip-out process to remove the storage node oxide within the cell region
Data Source
AI summary
A semiconductor device having a high aspect cylindrical capacitor and a method for fabricating the same is presented. The high aspect cylindrical type capacitor is a stable structure which is not prone to causing bunker defects and losses in a guard ring. The semiconductor device includes the cylindrical type capacitor structure, a storage node oxide, a guard ring hole, a conductive layer, and a capping oxide. The cylindrical type capacitor structure in a cell region includes a cylindrical type lower electrode, a dielectric and an upper electrode. The storage node oxide is in a peripheral region over the semiconductor substrate. The conductive layer coating the guard ring hole. The guard ring hole at a boundary of the peripheral region that adjoins the cell region over the semiconductor substrate. The capping oxide partially fills in a part of the conductive layer. The gapfill film filling in the rest of the conductive layer.