PMOS Transistor Boron Out-Diffusion Barrier
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Solution Overview
Problem
In PMOS transistors, the high diffusivity of Boron ions during the annealing process after low-energy ion implantation leads to out-diffusion, preventing impurities from reaching the desired implantation level, which slows down the transistor speed.
Innovation Solution
A semiconductor device and fabrication method that includes forming a silicon oxide nitride layer on the source/drain area to prevent Boron ion out-diffusion, using a nitrogen plasma process to create a barrier that maintains impurity density during annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low-energy ion implantation is used to achieve reduced junction depth, then the junction depth is reduced to about 20 nm, but Boron ions out-diffuse during annealing due to high diffusivity, preventing impurities from reaching the desired implantation level and slowing down transistor speed
Solution Approach 1:
A silicon oxide nitride layer is introduced as an intermediary barrier between the semiconductor substrate and the external environment. This layer specifically blocks Boron ion out-diffusion during annealing while allowing the low-energy implantation process to achieve the desired shallow junction depth of about 20 nm, thereby preventing transistor speed degradation
Solution Approach 2:
The invention uses a composite silicon oxide nitride layer that combines properties of both oxide and nitride materials. This composite structure provides superior Boron ion blocking capability compared to single-material layers, enabling the maintenance of impurity density at the shallow junction depth while preventing out-diffusion during thermal processing
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 silicon oxide nitride layer effectively prevents Boron ion out-diffusion, ensuring the PMOS transistor retains its operation speed and prevents increased extension resistance, thereby improving semiconductor device performance.
Implementation Method 1
forming a silicon oxide nitride layer on the source/drain area to prevent Boron ion out-diffusion, using a nitrogen plasma process to create a barrier
Implementation Method 2
in an annealing process for activating the high density Boron ions in source/drain area 133
Implementation Method 3
Boron ions may be out-diffused even if the ion implantation process is performed with a low ion implantation energy
Implementation Method 4
by implanting high density impurities, such as Boron ions, in source/drain area 133 at a low energy of about 1 KeV to 5 KeV
Data Source
AI summary
A semiconductor device, such as a positive channel metal-oxide semiconductor (PMOS) transistor, and a fabricating method thereof are provided. The semiconductor device includes: a gate insulation layer and a gate electrode, a semiconductor substrate, a spacer formed on side walls of the gate insulation layer and the gate electrode, a lightly doped drain (LDD) area formed on the semiconductor substrate at both sides of the gate electrode, a source/drain area formed on the semiconductor substrate at both sides of the gate electrode, and an oxide-nitride layer formed on the gate electrode and on the source/drain area.