Etch Stop Layer Breakthrough While Protecting FinFET Contacts
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in efficiently forming contacts to underlying layers while protecting conductive elements during etching, particularly in advanced semiconductor devices like FinFETs, where etch stop layers are involved.
Innovation Solution
A photoresist layer is used to protect dielectric layers and conductive elements during etching, allowing selective etching of etch stop layers without removing the photoresist, which is then left in place to shield other metal features, and another etchant is used to break through the etch stop layer, ensuring minimal impact on the dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoresist layer is used to protect dielectric layers during etching, then the integrity of dielectric layers is maintained, but the etch stop layer cannot be effectively broken through
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a second etchant with different composition and properties than the first etchant. The second etchant is specifically selected to have high etch rate and selectivity for the etch stop layer, while the photoresist layer remains intact due to its resistance to this specific etchant chemistry.
2Ease of manufacture
If the photoresist layer is removed after dielectric layer etching, then subsequent etching of etch stop layer is easier, but conductive elements lose protection during etching
Solution Approach 1:
The photoresist layer serves as an intermediary protective element that remains in place during the etch stop layer etching process. The second etchant is specifically chosen to etch the etch stop layer while being resistant to the photoresist material, allowing the photoresist to continue protecting conductive elements without interfering with the etching process.
3Manufacturing precision
If a first etchant is used to etch the dielectric layer, then the dielectric layer is effectively removed, but the etch stop layer remains intact
Solution Approach 1:
The patent employs a parameter change by switching from a first etchant optimized for dielectric layer removal to a second etchant optimized for etch stop layer removal. The second etchant has different chemical properties, composition, and etch selectivity characteristics that enable it to effectively etch the etch stop layer while the photoresist layer provides protection and remains intact.
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 precise and protective etching of etch stop layers in semiconductor devices, maintaining the integrity of dielectric and conductive elements, and facilitating the formation of reliable contacts.
Implementation Method 1
A separate etchant is then used to break through the etch stop layer. This next etchant is selective to the etch stop layer and will not significantly etch the dielectric layer.
Implementation Method 2
The etch stop layer is etched to break through the etch stop layer while the photo resist layer is maintained over the dielectric layer.
Data Source
AI summary
A photo resist layer is used to protect a dielectric layer and conductive elements embedded in the dielectric layer when patterning an etch stop layer underlying the dielectric layer. The photo resist layer may further be used to etch another dielectric layer underlying the etch stop layer, where etching the next dielectric layer exposes a contact, such as a gate contact. The bottom layer can be used to protect the conductive elements embedded in the dielectric layer from a wet etchant used to etch the etch stop layer.