Comparison between RTA (Rapid Thermal Annealing) and RTP (Rapid Thermal Processing)

### Comparison between RTA (Rapid Thermal Annealing) and RTP (Rapid Thermal Processing)

I. Core Definitions and Principles  

1. RTA (Rapid Thermal Annealing)  

   - Definition: A short-duration, high-temperature annealing process that achieves specific annealing goals by rapidly heating (up to 100°C/second or higher) and cooling within a few seconds to tens of seconds.  

   - Principle: Utilizes high temperatures to activate impurity diffusion, repair ion implantation damage, or activate dopants while minimizing excessive impurity diffusion caused by prolonged heating.  

2. RTP (Rapid Thermal Processing)  

   - Definition: A general term for all thermal processes that utilize rapid heating/cooling, including but not limited to annealing, oxidation, nitridation, alloying, etc.  

   - Principle: Precisely controls the temperature-time profile to modulate material structure, interface properties, or impurity distribution.  

II. Application Examples  

1. RTA Example: Post-Ion Implantation Activation Annealing  

   - Scenario: In CMOS fabrication, after boron (B⁺) implantation to form P-type source/drain regions, RTA is used to activate B atoms and repair the crystal lattice.  

   - Process Parameters: Heating rate of 100°C/second, hold at 1050°C for 5 seconds, cooling rate of 50°C/second.  

   - Objective: Achieve >90% activation of B atoms in substitutional Si lattice positions while limiting B diffusion (junction depth <50nm).  

2. RTP Example: Rapid Thermal Oxidation (RTO)  

   - Scenario: In FinFET processes, RTP is used to grow ultra-thin (1–3nm) high-quality SiO₂ gate dielectrics on silicon surfaces.  

   - Process Parameters: Oxygen (O₂) atmosphere, 900°C for 60 seconds to form 2nm-thick SiO₂.  

   - Objective: Precisely control oxide thickness while preventing Fin structure deformation due to high temperatures.  

III. Relationship and Overlap  

- RTA as a Subset of RTP: All RTA processes are part of RTP, but RTP encompasses broader applications like oxidation and nitridation.  

- Equipment Compatibility: Modern RTP systems support multiple process modes (e.g., RTA, RTO, RTN) via software configuration.  

- Technological Evolution: Early RTA systems had simple temperature profiles, while advanced RTP systems now offer complex waveform control (e.g., "spike annealing" combined with "ramp cooling"), blurring the distinction between the two.  

IV. How to Choose?  

- Select RTA if the goal is rapid impurity activation or lattice repair with strict diffusion control (e.g., shallow junctions in advanced nodes).  

- Select RTP for material surface modification, thin film growth, or complex chemical reactions (e.g., surface pre-treatment before high-k dielectric deposition).  

Example: In sub-7nm processes, RTA is used for dopant activation after EUV lithography, while RTP handles interface engineering in high-k/metal gate stacks, ensuring optimization of device performance.