Storage Node Electrode Fabrication via Multi-Layer HDP Oxide Films
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Solution Overview
Problem
As semiconductor devices shrink in size due to increased integration density, there is a challenge in ensuring adequate capacitance for capacitors, particularly in DRAMs, where traditional methods like the meta-stable poly silicon (MPS) process face limitations in increasing capacitance due to physical constraints and space margins, leading to issues like bridge formation and limited capacitance enhancement.
Innovation Solution
A method involving a series of high-density plasma (HDP) processes to form multiple oxide films with controlled etching rates and pre-heating steps, using gases like oxygen, silane, helium, hydrogen, and argon, to create a support film structure that enhances capacitance without carbon residue, thereby preventing bridge defects and maintaining process stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of a capacitor is increased to improve capacitance, then the capacitance increases, but the process margin of photo process and etching process becomes deficient
Solution Approach 1:
The patent transitions from increasing capacitor height (vertical dimension) to increasing capacitor area (horizontal dimension) by forming a multi-layer oxide film structure with different etching rates. This allows capacitance enhancement through area expansion rather than height increase, thereby maintaining adequate process margins for photo and etching processes.
Solution Approach 2:
The patent employs a composite oxide film structure consisting of multiple layers with different etching rates (first oxide film with slower etching rate, second oxide film with faster etching rate). This composite structure enables selective removal of portions during the dip-out process, creating the desired capacitor area expansion while maintaining manufacturing precision.
2Quantity of substance
If the MPS process is used to increase capacitor area, then the capacitance increases, but bridge formation occurs at the upper portion of the capacitor
Solution Approach 1:
The patent segments the oxide film into multiple layers with different etching rates, allowing selective removal of specific portions during the dip-out process. This segmentation enables precise control over the capacitor structure formation, preventing bridge defects while achieving the desired area expansion for increased capacitance.
Solution Approach 2:
The patent applies local quality by creating regions with different etching rates within the oxide film structure. The first oxide film has a slower etching rate while the second oxide film has a faster etching rate, allowing selective removal in specific areas during dip-out. This local differentiation prevents bridge formation while achieving capacitor area expansion.
3Quantity of substance
If the concave structure is used to increase capacitance, then one surface of the capacitor is utilized, but the capacitance enhancement is limited
Solution Approach 1:
The patent moves from utilizing only one surface (concave structure) to utilizing multiple surfaces by forming a multi-layer oxide film structure. The selective removal of oxide film portions creates a three-dimensional structure with increased surface area, enabling greater capacitance enhancement capability beyond the limitations of single-surface concave structures.
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 effectively increases capacitance while preventing bridge defects and improving process reliability by forming storage node electrodes with controlled plasma processes at low temperatures, ensuring efficient capacitance enhancement and reducing defects caused by carbon residue.
Implementation Method 1
performing a primary high density plasma (HDP) process to form a first HDP oxide film
Implementation Method 2
forming a plasma oxide film by oxidizing a partial surface of the etch stop film
Implementation Method 3
an etching rate of the second HDP oxide film being slower than an etching rate of the first HDP oxide film
Data Source
AI summary
A method for fabricating a storage node electrode in a semiconductor device includes: performing a primary high density plasma (HDP) process to form a first HDP oxide film over an etch stop film; performing a secondary HDP process to form a second HDP oxide film on the first HDP oxide film; forming a support film over the second HDP oxide film; performing a tertiary HDP process to form a third HDP oxide film over the support film; forming a storage node electrode on an exposed surface of the storage node contact hole; partially removing the third HDP oxide film and the support film so that a support pattern supporting the storage node electrode is formed; and exposing an outer surface of the storage node electrode by removing the second HDP oxide film and the first HDP oxide film.