Sacrificial Capping Layer for Plasma Implant Passivation

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Solution Overview

Problem

Plasma implantation processes for semiconductor workpieces face challenges due to excessive etching caused by radicals and excited species, which can degrade device performance and reliability, particularly in advanced transistors with high germanium concentrated SiGe films.

Innovation Solution

A sacrificial capping layer is applied on the workpiece surface to protect it from etching during ion implantation, where passivating species like hydrogen, deuterium, or fluorine are implanted through the layer, with the layer being selectively etched by radicals and excited molecules, thereby minimizing workpiece etching while achieving desired doping levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If plasma implantation is used to introduce passivating species, then high doping levels can be achieved at high dose rate, but radicals and excited species cause excessive etching of surface layers

Engineering Contradiction:

Improvedoping levelVSAvoidsurface etching

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

A sacrificial capping layer is introduced as an intermediary between the plasma environment and the workpiece surface. This layer absorbs the harmful radicals and excited species that would otherwise etch the workpiece, while still allowing passivating species to be implanted through it. The capping layer acts as a protective mediator that enables the plasma implantation process to proceed without damaging the underlying surface layers.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sacrificial capping layer is designed to be consumed during the implantation process. It serves as a disposable protective layer that gets etched away by radicals and excited species, sacrificing itself to protect the workpiece. After serving its protective function, the layer is removed or completely consumed, having fulfilled its purpose of enabling high-dose implantation without surface damage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If a sacrificial capping layer is applied to protect from etching, then surface etching is reduced, but processing time and complexity increase

Engineering Contradiction:

Improvesurface etchingVSAvoidprocessing time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The application of the sacrificial capping layer and the plasma implantation process are merged into a single integrated process. The capping layer is applied in-chamber, and the implantation proceeds without breaking vacuum or moving the workpiece between chambers. This combination eliminates the time losses associated with chamber transitions and allows both protective layer formation and species implantation to occur in sequence within the same plasma environment.

Inventive Principle:

Principle #5Merging (Combining)

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 method effectively reduces surface etching, enhances gate oxide reliability, and maintains high doping levels without significantly increasing processing time or cost, thereby improving the performance and reliability of semiconductor devices.

Implementation Method 1

creating a plasma comprising a passivating species within the plasma chamber, wherein the passivating species is selected from the group consisting of hydrogen, deuterium, fluorine and gas mixtures containing hydrogen, deuterium or fluorine as a diluent or primary processing gas and wherein ions, radicals and excited molecules of the passivating species are generated

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

ions, radicals and excited molecules of the passivating species are generated

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

performing an implant process wherein the ions of the passivation species are implanted through the sacrificial capping layer and into the portion by applying a bias voltage to the workpiece

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 4

wherein during the implant process, the radicals and excited molecules etch the sacrificial capping layer

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS11501972B2Sacrificial capping layer for passivation using plasma-based implant process

Publication Date: 2022.11.15 APPLIED MATERIALS INC

AI summary

An apparatus and method of processing a workpiece is disclosed, where a sacrificial capping layer is created on a top surface of a workpiece. That workpiece is then exposed to an ion implantation process, where select species are used to passivate the workpiece. While the implant process is ongoing, radicals and excited species etch the sacrificial capping layer. This reduces the amount of etching that the workpiece experiences. In certain embodiments, the thickness of the sacrificial capping layer is selected based on the total time used for the implant process and the etch rate. The total time used for the implant process may be a function of desired dose, bias voltage, plasma power and other parameters. In some embodiments, the sacrificial capping layer is applied prior to the implant process. In other embodiments, material is added to the sacrificial capping layer during the implant process.