PLAD Fin Height Loss Minimization via Voltage Ramping
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Solution Overview
Problem
Conventional semiconductor manufacturing processes, such as ion implantation, face challenges in achieving conformal doping profiles for finFETs due to dopant shadowing effects in aggressive geometries, leading to non-conformal dopant profiles and fin height loss during plasma doping processes.
Innovation Solution
A plasma doping (PLAD) process with a combination of nominally constant voltage values and voltage ramp conditions is used to form lightly doped source/drain regions, replacing pulsed DC bias voltage with DC steady state and ramp voltage steps to prevent ion bombardment damage and achieve highly conformal doping profiles with minimal fin height loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion implantation is used for doping finFETs, then the doping process can be completed, but dopant shadowing effects occur in aggressive geometries leading to non-conformal dopant profiles
Solution Approach 1:
The patent replaces conventional ion implantation (mechanical/physical bombardment) with plasma doping using volatile dopant species. The dopants are delivered through plasma chemistry rather than direct ion bombardment, eliminating shadowing effects and achieving conformal doping profiles on fin structures with aggressive geometries.
Solution Approach 2:
The patent changes the physical and chemical parameters of the doping process by using volatile dopant species in plasma form rather than solid ion beams. This parameter change allows dopants to reach all surfaces of the fin structure uniformly, achieving conformal doping profiles that match the fin geometry.
2Manufacturing precision
If plasma doping is used to achieve conformal doping profiles, then dopant distribution improves, but fin height loss occurs due to ion bombardment damage
Solution Approach 1:
The patent replaces mechanical ion bombardment with a chemical plasma-based doping process. Volatile dopant species are delivered through plasma chemistry and surface reactions rather than physical ion impact, eliminating damage to the fin structure while maintaining conformal doping profiles.
Solution Approach 2:
The patent introduces plasma as an intermediary medium to deliver dopants to the fin surface. Instead of direct ion impact, the plasma environment facilitates dopant delivery through chemical reactions and surface adsorption, protecting the fin structure from bombardment damage while achieving uniform doping.
3Productivity
If pulsed DC bias voltage is applied during plasma doping, then the doping process can proceed, but ion bombardment damage occurs leading to fin height loss
Solution Approach 1:
The patent replaces the pulsed DC bias voltage mechanism (which causes ion acceleration and bombardment) with a plasma-based dopant delivery system. Dopants are delivered through plasma chemistry and surface reactions, eliminating the need for high voltage pulses and the associated ion bombardment damage.
Solution Approach 2:
The patent uses plasma as an intermediary to deliver dopants without requiring high voltage biasing. The plasma environment enables dopant transport and surface incorporation through chemical mechanisms rather than electrical field-driven ion bombardment, protecting the fin structure from damage.
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 PLAD process results in reduced parallel resistance and enhanced transistor performance by ensuring conformal doping profiles and minimizing fin height loss, thereby improving overall transistor performance compared to conventional methods.
Implementation Method 1
ion bombardment damage to the fin's top and sidewall surfaces
Implementation Method 2
plasma doping (PLAD) process
Implementation Method 3
applying a DC bias voltage to the substrate to accelerate the ionized dopant species toward the surface of the substrate
Implementation Method 4
a plasma doping (PLAD) process with a combination of nominally constant voltage values and voltage ramp conditions... Exposing the substrate to a multiple-cycle plasma doping process having an RF plasma power
Data Source
AI summary
A plasma doping process provides conformal doping profiles for lightly doped source/drain regions in fins, and reduces the plasma doping induced fin height loss. The plasma doping process overcomes the limitations caused by traditional plasma doping processes in fin structures that feature aggressive aspect ratios and tights pitches. Semiconductor devices with conformal lightly doped S/D regions and reduced fin height loss demonstrate reduced parallel resistance (Rp) and improved transistor performance.