Semiconductor Contact Structures Using Permanent Antireflection Coating
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Solution Overview
Problem
Conventional semiconductor contact formation processes face challenges in accurately forming contacts at sub-80 nm pitches due to the shrinking of nitride stop layer thickness and silicide layer dimensions, leading to misalignment, aspect ratio dependent etching issues, and increased contact resistance.
Innovation Solution
The use of a permanent antireflection coating and a patternable dielectric composition that acts as both a photoresist and a dielectric material, allowing for direct patterning and curing to form electrically conductive contact structures without the need for nitride or oxide layers, thereby reducing plasma etching and simplifying the integration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional five-step etching process is used to form contact holes, then contact patterns can be transferred into oxide layer, but plasma-induced damage occurs and process complexity increases
Solution Approach 1:
The patent removes the nitride stop layer from the conventional contact formation process. By eliminating this intermediate layer, the process reduces plasma exposure steps and minimizes plasma-induced damage to the silicide layer while maintaining accurate contact pattern transfer through direct oxide etching to the silicide contact pads.
Solution Approach 2:
The patent performs preliminary planarization of the oxide layer thickness variation before contact patterning. By pre-flattening the oxide surface over gate and source/drain areas, the process ensures uniform etching depth and accurate contact hole formation without requiring multiple etching steps, thereby reducing overall plasma exposure.
2Manufacturing precision
If nitride stop layer is used in sub-80 nm pitch devices, then oxide etching can be stopped on nitride layer, but space for nitride layer becomes insufficient and misalignment occurs
Solution Approach 1:
The patent extracts and eliminates the nitride stop layer entirely from sub-80 nm pitch device fabrication. Instead of attempting to fit the nitride layer in the reduced pitch space, the process directly etches through the oxide layer to the silicide contact pads, eliminating the space conflict and misalignment issues associated with the nitride layer.
3Adaptability or versatility
If self-aligned contact integration scheme is used to accommodate sub-80 nm pitches, then device integration is achieved, but contact hole open area shrinks causing severe ARDE effect
Solution Approach 1:
The patent applies a preliminary oxide planarization step that exceeds the minimum required by performing additional flattening beyond the immediate contact area. This creates a more uniform oxide thickness profile across the entire contact region, compensating for the reduced contact hole open area and minimizing ARDE effects in self-aligned contact structures.
4Manufacturing precision
If multiple etching steps are performed to form contact holes, then contact patterns are accurately transferred, but process time increases and productivity decreases
Solution Approach 1:
The patent removes the nitride stop layer etching step from the conventional five-step process, reducing the total number of etching steps. This elimination simplifies the contact formation process while maintaining accurate pattern transfer by directly etching the oxide layer to the silicide contact pads in a single etching operation.
Solution Approach 2:
The patent combines the oxide etching and nitride stop layer removal into a single etching step by eliminating the nitride layer entirely. This merging of functions reduces the total process time and increases productivity while maintaining the necessary etching precision through the preliminary oxide planarization.
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 approach minimizes plasma-induced damage, reduces the number of process steps, and improves pattern profile control, resulting in lower contact resistance and more efficient contact formation, especially in tight pitch regimes.
Implementation Method 1
patterning the interlevel dielectric composition to form contact holes by exposing the interlevel dielectric composition to radiation and developing the interlevel dielectric composition with a chemical solution; curing the interlevel dielectric composition thereby converting the interlevel dielectric composition into a patterned permanent interlevel dielectric layer
Data Source
AI summary
A contact structure includes a permanent antireflection coating formed on a substrate having contact pads. A patterned dielectric layer is formed on the antireflective coating. The patterned dielectric layer and the permanent antireflective coating form openings. The openings correspond with locations of the contact pads. Contact structures are formed in the openings to make electrical contact with the contacts pads such that the patterned dielectric layer and the permanent antireflective coating each have a conductively filled region forming the contact structures.