What is the difference between RTA and RTP？

Abstract：

This article deeply analyzes the core differences between rapid thermal annealing (RTA) and rapid thermal processing (RTP), from five dimensions: definition, principle, practical application, the relationship between the two to selection recommendations, to help semiconductor engineering technicians understand the positioning and applicable scenarios of the two in the process links, and provide professional heat treatment references for advanced manufacturing nodes.

Ⅰ. Core Definitions and Principles

1.1 RTA (Rapid Thermal Annealing)

Definition: A short-term high-temperature annealing process that achieves specific annealing objectives in a very short time (seconds to tens of seconds) through rapid heating (up to 100°C/second or higher) and cooling.

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

Key characteristics of RTA include:

● Extremely fast heating and cooling rates (≥100°C/second)

● Single-wafer processing

● No significant chemical reactions—primarily thermal diffusion or lattice repair

● Commonly used as an activation step following ion implantation

1.2 RTP (Rapid Thermal Processing)

Definition: A general term for rapid thermal processing, encompassing all thermal processes achieved through rapid heating/cooling, including but not limited to annealing, oxidation, nitriding, alloying, etc.

Principle: By precisely controlling the temperature-time curve, it regulates material structure, interface properties, or impurity distribution.

Key features of RTP include:

● Diverse process types (not limited to annealing)

● Capable of rapid heating and cooling

● Capable of configuring different atmospheric environments (e.g., O₂, N₂, NH₃, etc.)

● Capable of precisely controlling the time-temperature curve

II. Case Comparison

2.1 RTA example: Activation Annealing after Ion Implantation

Scenario: In CMOS manufacturing, after B⁺ is implanted to form P-type source and drain regions, RTA is used to activate B atoms and repair the crystal lattice.

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

Objective: To replace Si lattice positions with B atoms (activation rate > 90%) while limiting B diffusion (junction depth < 50 nm).

2.2 RTP example: Rapid thermal oxidation (RTO)

Scenario: In FinFET processes, RTP is used to form an ultra-thin (1–3 nm) high-quality SiO₂ gate dielectric on the silicon surface.

Process parameters: O₂ atmosphere, 900°C for 60 seconds, forming a 2 nm thick SiO₂ layer.

Objective: Precisely control the oxide layer thickness while avoiding high-temperature-induced deformation of the Fin structure.

Ⅲ. The Relationship and Overlap Between RTA and RTP

RTA is a subset of RTP: all RTA processes are included in RTP, but RTP also encompasses other processes such as oxidation and nitriding.

Equipment Compatibility: Modern RTP equipment typically supports multiple process modes, enabling functions such as RTA, RTO, and RTN through software switching.

Technological Evolution: Early RTA equipment only supported simple temperature curves, while next-generation RTP systems feature more complex waveform control (such as combining “peak annealing” with “slope cooling”), blurring the boundaries between the two.

Ⅳ. How to choose?

The choice of heat treatment method mainly depends on the purpose of the process:

Recommendation Summary:

If the goal is rapid, localized thermal annealing (such as activation after ion implantation), choose RTA.

If you need to perform multiple heat treatments involving atmospheric reactions (such as oxidation, nitriding, siliconization, etc.), RTP is more suitable.