Selective Etching for Ge Semiconductor Contacts
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Solution Overview
Problem
The semiconductor industry faces challenges in forming contacts on strained Ge-based source and drain regions in FinFETs without damaging the geometry, leading to increased contact resistivity and channel damage.
Innovation Solution
A process involving a Ge-containing contact region coated with SiO2 and Si3N4 layers, where selective etching using inductively coupled plasma exposes the Ge-containing region while preserving the geometry, allowing for contact creation without damaging the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional contact formation methods are used on strained Ge-based source and drain regions, then contact creation is achieved, but the geometry of the source and drain is damaged
Solution Approach 1:
The patent applies preliminary action by performing a selective etch process before contact formation to create a contact hole through the dielectric layers. This preliminary etching step defines the contact region boundaries precisely, ensuring that subsequent contact deposition occurs only in the intended area, thus preventing geometry damage to the strained Ge source and drain regions while enabling successful contact creation.
2Reliability
If contact formation is performed on Ge-containing regions, then electrical contact is established, but contact resistivity increases due to geometry damage
Solution Approach 1:
The patent replaces mechanical contact formation methods with a plasma-based selective etching process. Instead of using mechanical means that could damage the Ge geometry, the plasma etch chemically removes dielectric material to create contact holes, preserving the integrity of the strained Ge regions and minimizing contact resistivity while establishing reliable electrical contact.
3Productivity
If aggressive etching is used to create contact holes, then contact formation speed increases, but channel damage occurs
Solution Approach 1:
The patent applies local quality by using selective etching with specific chemistry that targets only the dielectric layers (such as silicon oxide or silicon nitride) while being inherently selective against damaging the Ge-containing channel regions. This localized chemical selectivity enables efficient contact hole formation through the dielectric without causing channel damage, maintaining both productivity and device integrity.
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 enables the formation of good contacts on Ge-containing regions while maintaining the original dimensions, reducing contact resistivity and preventing channel damage, thereby improving the electronic properties of the contacts.
Implementation Method 1
Etching selectively the Si3N4 layer by means of an inductively coupled plasma, thereby exposing the underlying SiO2 layer if present or the Ge-containing contact region
Implementation Method 2
Etching selectively the SiO2 layer if present, thereby exposing the Ge-containing contact region
Data Source
AI summary
A process for creating a contact on a Ge-containing contact region of a semiconductor structure, said process comprising the steps of:providing said semiconductor structure comprising:(i) a Ge-containing contact region,(ii) optionally, a SiO2 layer coating said Ge-containing contact region,(iii) a Si3N4 layer coating said SiO2 layer if present or said Ge-containing contact region;etching selectively the Si3N4 layer by means of an inductively coupled plasma, thereby exposing the underlying SiO2 layer if present or the Ge-containing contact region;etching selectively the SiO2 layer if present, thereby exposing the SiGe:B contact region; andcreating said contact on said Ge-containing contact region.