Pulsed Ion Implant Amorphization Control
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Solution Overview
Problem
Current semiconductor processing techniques, such as pre-amorphization implant (PAI), face challenges in achieving controlled amorphization and minimizing substrate damage, particularly with high ion doses leading to sputtering and swelling, and require additional process steps to reduce channeling effects, while cryogenic approaches lower wafer throughput.
Innovation Solution
A pulsed plasma processing method using a plasma immersion tool with a pulse routine of extraction voltage pulses to direct ion pulses to a substrate, where the ion dose per pulse is greater than a threshold for low dose amorphization, allowing for controlled amorphization and reduced damage by varying the dose per pulse (DPP) while maintaining a constant total implant dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high ion dose implantation is used to achieve amorphization, then the amorphous region is successfully formed, but significant sputtering and swelling of the substrate occurs
Solution Approach 1:
The total ion dose is segmented into multiple smaller pulses delivered intermittently. This allows the amorphization effect to accumulate while preventing the substrate damage that occurs with single high-dose implantation. The pulse intervals enable damage relaxation between deliveries, resolving the contradiction between achieving amorphization and avoiding sputtering/swelling.
Solution Approach 2:
The ion implantation is performed as periodic pulses rather than continuous delivery. The intermittent nature of the pulses allows the substrate to partially recover or relax between implantation events, preventing cumulative damage while still achieving the desired amorphous layer formation through accumulated dose.
2Manufacturing precision
If additional ion implantation is performed to control dopant placement, then channeling effects are suppressed, but the process complexity increases
Solution Approach 1:
The amorphous layer is formed as a preliminary step before dopant implantation. This pre-amorphization creates a uniform target structure that inherently suppresses channeling effects during subsequent dopant implantation, eliminating the need for additional complex process steps to control dopant placement.
Solution Approach 2:
The ion dose per pulse is changed to be greater than the threshold for low-dose amorphization. This parameter change enables effective amorphization with reduced total dose, which in turn simplifies the overall process by reducing the need for additional implantation steps to achieve proper dopant placement control.
3Manufacturing precision
If cryogenic implantation is used to generate sharper boundaries, then the amorphous/crystalline boundary is improved, but wafer throughput decreases
Solution Approach 1:
The substrate temperature parameter is changed from cryogenic to room temperature operation. Combined with the pulsed implantation regime and optimized dose per pulse, this parameter change achieves effective amorphization with sharp boundaries without requiring cooling infrastructure, thereby maintaining high wafer throughput.
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 enables precise control over the degree of amorphization and damage accumulation, reducing the total ion dose required for amorphization, minimizing substrate damage, and increasing productivity by allowing amorphization at room temperature with lower sputtering and swelling, and providing precise control over the PAI process.
Implementation Method 1
initiating a plasma in the plasma chamber, the plasma comprising an amorphizing ion species
Implementation Method 2
a plurality of ion pulses are directed to the substrate, wherein an ion dose per pulse is greater than a threshold for low dose amorphization
Data Source
AI summary
A method may include providing a substrate in a plasma chamber, the substrate comprising a monocrystalline semiconductor, having an upper surface. The method may include initiating a plasma in the plasma chamber, the plasma comprising an amorphizing ion species, and applying a pulse routine to the substrate, the pulse routine comprising a plurality of extraction voltage pulses, wherein a plurality of ion pulses are directed to the substrate, and wherein an ion dose per pulse is greater than a threshold for low dose amorphization.