One-Side Contact Region Formation in Vertical Transistors
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Solution Overview
Problem
The existing methods for opening a one-side contact region of a vertical transistor are complex and time-consuming, hindering the integration and capacity of semiconductor memory devices like DRAM and flash memory.
Innovation Solution
A method involving the formation of multiple liner and sacrificial layers, followed by plasma doping and tilt ion implantation processes to selectively dope impurities into a polysilicon layer, allowing for efficient exposure and formation of a one-side contact region, which is then used to fabricate a one-side junction region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to open the one-side contact region, then the contact region can be formed, but the process becomes complex and time-consuming
Solution Approach 1:
The patent applies preliminary action by forming the first liner layer on the substrate before any trench formation or contact opening processes. This pre-formed liner layer serves as a protective and guiding structure throughout subsequent processing steps, eliminating the need for multiple separate liner formation steps and reducing overall process time while maintaining manufacturing precision.
Solution Approach 2:
The first liner layer serves multiple functions simultaneously: it acts as a protective layer during trench formation, a mask during plasma doping, and a structural guide during contact region opening. This multi-functionality consolidates what would traditionally require multiple separate layers and processes into a single universal element, significantly reducing process complexity and time.
2Manufacturing precision
If multiple liner and sacrificial layers are formed, then the one-side contact region can be precisely opened, but the device structure becomes more complex
Solution Approach 1:
The patent extracts and eliminates unnecessary liner layers and sacrificial layers from the conventional structure. By using a single first liner layer that persists through all processing steps rather than multiple temporary layers that must be added and removed, the design simplifies the layer structure while maintaining the precision needed for contact region formation.
Solution Approach 2:
The patent applies local quality by selectively doping the polysilicon layer only in specific regions where the one-side contact region needs to be formed. The plasma doping process targets only the exposed portions of the polysilicon layer, creating locally modified regions with precise impurity concentrations exactly where needed, without requiring complex global structuring.
3Manufacturing precision
If plasma doping and tilt ion implantation are used, then impurity distribution is enhanced, but the process time increases
Solution Approach 1:
The patent merges the plasma doping process and tilt ion implantation process into a single integrated sequence that operates continuously on the polysilicon layer. By combining these two doping methods that work synergistically—plasma doping providing initial impurity distribution and tilt ion implantation enhancing it—the patent achieves superior impurity distribution without requiring separate, time-consuming processing cycles.
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 reduces the time required for the overall process, enhances impurity ion distribution, and improves the selectivity between doped and undoped portions, thereby increasing the efficiency and integration density of semiconductor devices.
Implementation Method 1
selectively doping impurities into the polysilicon layer by performing a plasma doping process and a tilt ion implantation process on the polysilicon layer
Implementation Method 2
selectively doping impurities into the polysilicon layer by performing a plasma doping process and a tilt ion implantation process on the polysilicon layer
Data Source
AI summary
A method for opening a one-side contact region of a vertical transistor is provided. The one-side contact region of the vertical transistor is opened using a polysilicon layer, a certain portion of which can be selectively removed by a selective ion implantation process. In order to selectively remove the polysilicon layer formed on one of both sides of an active region, at which the one-side contact is to be formed, impurity ion implantation is performed in a direction vertical to the polysilicon layer by a plasma doping process, and a tilt ion implantation using an existing ion implantation process is performed. In this manner, the polysilicon layer is selectively doped, and the undoped portion of the polysilicon layer is selectively removed.