Offset Oxide Etching Using Reactive Gas Cluster Ion Beam
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Solution Overview
Problem
The challenge in semiconductor device fabrication lies in achieving uniform ion implantation and thickness uniformity of thin films, particularly in vertical cell type semiconductor devices where traditional methods fail to ensure consistent ion dispersion and thickness control.
Innovation Solution
A method involving the formation of a preliminary stack structure with a through hole, followed by the deposition of protection and dielectric layers, and the use of a reactive gas cluster ion beam to scan and etch an offset oxide layer, adjusting scan speeds based on measured thickness data to reduce thickness dispersion to less than 10 Å, allowing for precise ion implantation through the offset oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional ion implantation methods are used in vertical cell type semiconductor devices, then the fabrication process is simple, but ion dispersion uniformity and thickness control are poor
Solution Approach 1:
The offset oxide layer is formed in advance before ion implantation, serving as a thickness reference and control layer. This preliminary structure enables precise control of the subsequent ion implantation process by providing a known thickness baseline that guides the etching and implantation parameters.
Solution Approach 2:
The patent changes the physical and chemical parameters of the oxide layer by forming an offset oxide with specific thickness characteristics, then using reactive gas cluster ion beam etching to modify its thickness distribution. This parameter transformation from a simple deposited layer to a precisely controlled etched layer enables uniform ion implantation.
2Manufacturing precision
If uniform thickness of thin film is achieved through traditional deposition, then deposition process is straightforward, but thickness dispersion remains high
Solution Approach 1:
The patent replaces traditional mechanical deposition control with a chemical etching approach using reactive gas cluster ion beams. Instead of relying solely on deposition uniformity, the method uses controlled chemical removal to achieve the desired thickness uniformity, substituting a chemical process for a mechanical one.
Solution Approach 2:
The offset oxide layer thickness is measured and used as feedback to control the etching process. The thickness data from the offset oxide provides real-time information that guides the reactive gas cluster ion beam etching parameters, creating a closed-loop control system that achieves high thickness uniformity.
3Manufacturing precision
If reactive gas cluster ion beam is used to etch offset oxide with varying thickness, then thickness dispersion is reduced, but etching process complexity increases
Solution Approach 1:
The etching process applies different local conditions to different regions of the offset oxide based on its thickness variations. By using reactive gas cluster ion beams with controlled parameters, the method creates locally optimized etching conditions that uniformly reduce thickness across regions with initially different thicknesses, achieving homogeneous results from heterogeneous starting conditions.
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 significantly improves ion implantation uniformity and reduces thickness dispersion, enhancing the semiconductor device's performance by optimizing the projection range and threshold voltage dispersion.
Implementation Method 1
scanning the offset oxide using a reactive gas cluster ion beam
Implementation Method 2
forming the gas cluster using a reactive gas, and the reactive gas may include one of nitrogen tetrafluoride (NF3), tetrafluoromethane (CF4), and trifluoromethane (CHF3)
Implementation Method 3
implanting ions through the offset oxide into the channel pattern
Data Source
AI summary
According to example embodiments of inventive concepts, a method of fabricating a semiconductor device includes: forming a preliminary stack structure, the preliminary stack structure defining a through hole; forming a protection layer and a dielectric layer in the through hole; forming a channel pattern, a gapfill pattern, and a contact pattern in the through hole; forming an offset oxide on the preliminary stack structure; measuring thickness data of the offset oxide; and scanning the offset oxide using a reactive gas cluster ion beam. The scanning the offset oxide includes setting a scan speed based on the measured thickness data of the offset oxide, and forming a gas cluster.