Recessed Gate Transistor with Segmented Work Function for GIDL Reduction
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Solution Overview
Problem
In semiconductor memory devices, the gate-induced drain leakage (GIDL) current causes performance degradation due to reduced threshold voltage, which affects the retention and refresh characteristics of semiconductor devices, and existing methods fail to effectively reduce this leakage while maintaining a high threshold voltage.
Innovation Solution
A transistor design with a recessed gate structure where the upper portion of the gate electrode is doped with nitrogen, oxygen, arsenic, aluminum, or hydrogen ions, while the lower portion maintains a high work function, reducing GIDL current and maintaining threshold voltage, thereby reducing leakage current and improving read and write times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If nitrogen ions are doped into the entire gate electrode to reduce work function and decrease GIDL current, then GIDL current is reduced, but threshold voltage is reduced causing performance degradation
Solution Approach 1:
The gate electrode is divided into two distinct regions: a first region (lower portion) with high work function that maintains threshold voltage, and a second region (upper portion) with reduced work function that decreases GIDL current. This segmentation allows each region to perform its specific function independently without interfering with the other.
Solution Approach 2:
Different portions of the gate electrode are given different doping concentrations and material compositions tailored to their specific functions. The lower portion maintains high work function properties for threshold voltage control, while the upper portion has reduced work function properties for GIDL current suppression.
2Ease of manufacture
If a planar gate structure is used, then manufacturing is simple, but the gate and junction region contact area is large increasing GIDL current
Solution Approach 1:
The gate electrode transitions from a two-dimensional planar structure to a three-dimensional structure with vertical depth. The gate is formed with a first region at a lower depth and a second region at a greater depth, utilizing the vertical dimension to reduce the contact area with the junction region while maintaining manufacturability through standard doping and deposition processes.
3Object-generated harmful factors
If the work function of the gate is reduced to decrease GIDL current, then GIDL current is reduced, but transistor performance degrades due to reduced threshold voltage
Solution Approach 1:
The gate electrode is segmented into functional regions with different work functions. The first region maintains high work function to preserve threshold voltage and transistor performance, while the second region has reduced work function to suppress GIDL current, allowing both performance and leakage reduction goals to be achieved simultaneously.
Solution Approach 2:
The gate structure implements local quality variations where different regions have different material compositions and doping levels. The lower portion maintains properties optimized for threshold voltage control, while the upper portion has properties optimized for GIDL current reduction, enabling localized optimization of different functions.
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
The proposed solution effectively decreases GIDL current and maintains a high threshold voltage, enhancing the performance and reducing read and write times of semiconductor devices by optimizing the gate electrode doping.
Implementation Method 1
ions of one or more of nitrogen (N), oxygen (O), arsenic (As), aluminum (Al), and hydrogen (H) are doped into an upper portion of a gate electrode
Implementation Method 2
nitrogen composition of the TiN increases so that the work function (Φ) is reduced by approximately 100 mV
Data Source
AI summary
Provided are a transistor of a semiconductor device and a method for manufacturing the same. A gate induced drain leakage (GIDL) current is reduced by decreasing a work function at an upper portion of a gate electrode, and a threshold voltage of the transistor is maintained by maintaining a work function at a lower portion of the gate electrode at a high level, thereby reducing a leakage current of the transistor and reducing a read time and a write time of the semiconductor device. The transistor of the semiconductor device includes: a recess with a predetermined depth in a semiconductor substrate; a first gate electrode disposed within the recess; and a second gate electrode disposed on the first gate electrode into which ions of one or more of nitrogen (N), oxygen (O), arsenic (As), aluminum (Al), and hydrogen (H) are doped.