Fluoride Ion Doping for Gate Dielectric Reliability
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to ensure the reliability of the gate dielectric layer in high-k/metal gate last processes, particularly in reducing the effects of high fluoride ion doses without high temperature annealing, which can damage the semiconductor substrate.
Innovation Solution
A semiconductor device and manufacturing method involving high-pressure fluorine annealing to implant fluoride ions into the gate interface and high-k dielectric layers, forming a strong chemical bond and improving the stability of the gate dielectric layer while maintaining a low thermal budget.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large dose of fluoride ions is implanted into the gate dielectric layer to improve reliability and reduce NBTI/HCI effects, then the device reliability is improved, but the semiconductor substrate is damaged
Solution Approach 1:
The patent applies local quality by differentiating the treatment of core devices and IO devices. The gate interface layer of IO devices is doped with fluoride ions while the core device gate interface layer is not, allowing selective improvement of reliability in IO regions without subjecting the entire substrate to damaging fluoride doses. This localized approach targets the specific regions needing reliability enhancement while protecting sensitive areas.
Solution Approach 2:
The patent changes the doping parameters by controlling the fluoride ion concentration and distribution through selective doping of gate interface layers at different stages. By adjusting the doping dose and depth parameters for different device regions, the patent achieves improved reliability where needed while maintaining substrate integrity through parameter optimization rather than uniform high-dose doping.
2Strength
If high temperature annealing is used to form strong chemical bonds between Hf-F and Si-F interface, then the bond strength is improved, but the thermal budget is exceeded and substrate damage occurs
Solution Approach 1:
The patent applies preliminary action by doping the gate interface layer with fluoride ions before forming the high-k dielectric layer. This preliminary fluoride doping creates a fluorinated interface that will form strong bonds during subsequent processing, eliminating the need for high-temperature annealing to create the bonds. The strong Hf-F and Si-F bonds are established through the preliminary doping action rather than through high-temperature thermal processing.
Solution Approach 2:
The patent substitutes thermal processing with chemical doping to achieve bond formation. Instead of using high-temperature annealing (thermal mechanism) to form strong chemical bonds at the interface, the patent uses fluoride ion implantation and diffusion (chemical mechanism) to directly create the bonded interface structure, replacing the thermal field with a chemical field to achieve the same bonding objective without thermal damage.
3Ease of manufacture
If the dummy gate dielectric layer is removed prior to forming the gate dielectric layer in high-k/metal gate last process, then the manufacturing process is completed, but fluoride ion implantation into the high-k dielectric layer becomes difficult
Solution Approach 1:
The patent applies preliminary action by performing fluoride ion doping of the gate interface layer before removing the dummy gate dielectric layer and before forming the final high-k dielectric layer. This preliminary doping action ensures that the gate interface is properly fluorinated before subsequent processing steps, making the overall process easier to manufacture while achieving the desired fluoride incorporation without the complexity of post-formation implantation.
Solution Approach 2:
The patent inverts the conventional sequence by doping the gate interface layer with fluoride ions before removing the dummy gate dielectric layer, rather than attempting to dope after dummy gate removal. This inverted sequence simplifies the manufacturing process by performing the doping action when the gate structure is still in place and accessible, avoiding the complexity of implanting fluoride ions into the high-k dielectric layer after dummy gate removal.
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 method enhances the reliability and performance of semiconductor devices by forming a stable Hf—F and Si—F bond at the interface, reducing the risk of substrate damage from high fluoride doses and improving the quality of the gate dielectric layer.
Implementation Method 1
implantation of fluoride ions can be performed into a dummy dielectric layer and source/drain after the dummy dielectric layer (typically polysilicon) has been formed and before peak annealing of the source/drain of the device
Implementation Method 2
a strong chemical bond between Hf—F and Si—F interface can be formed
Implementation Method 3
high-k dielectric layer last technology requires a thermal budget that does not use high temperature annealing
Implementation Method 4
The fluoride ions can be fluorine or fluorine-containing compounds such as boron trifluoride). After annealing of the source and drain, a strong chemical bond between Hf—F and Si—F interface can be formed
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having a core device and an IO device. The core device includes a gate interface layer and a high-k dielectric layer on the gate interface layer. The IO device includes a gate interface layer and a high-k dielectric layer on the gate interface layer. The gate interface layer of the core device and the gate interface layer of the IO device each are doped with fluoride ions.