PECVD Nitride Layer Densification for Semiconductor Corner Protection
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Solution Overview
Problem
Existing semiconductor device fabrication processes face challenges in forming field isolation regions without causing undesired corner rounding and stress on semiconductor layers, leading to electrical defects and delamination issues.
Innovation Solution
A process involving patterning a semiconductor layer to form an opening, depositing a nitride layer using PECVD, densifying it, and selectively removing parts to create a remaining portion that protects the lower corners, allowing for conformal nitride deposition and reducing stress on the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal oxidation is performed to form a liner layer, then gate dielectric integrity is improved through corner rounding, but undesired corner rounding occurs at the bottom of the semiconductor layer causing stress and potential delamination
Solution Approach 1:
The patent applies local quality by creating a densified nitride layer specifically at the bottom of the opening where protection is needed, while leaving the upper regions accessible for thermal oxidation. This localized modification allows different regions to have different properties: the bottom region is protected from oxidation, while the upper corners can be rounded to improve gate dielectric integrity.
Solution Approach 2:
The patent implements preliminary action by forming the densified nitride layer at the bottom of the opening before performing thermal oxidation. This pre-established protective layer prevents the harmful bottom corner rounding from occurring during the subsequent thermal oxidation process, while still allowing the desired top corner rounding to improve gate dielectric integrity.
2Quantity of substance
If a nitride layer is deposited using sputtering to protect lower corners, then deposition is achieved, but the nitride layer is thicker at upper corners causing both corners to be protected and preventing selective rounding
Solution Approach 1:
The patent achieves local quality by using PECVD with a collimator to create a densified nitride layer that is selectively concentrated at the bottom of the opening. This directional deposition ensures the nitride layer is primarily formed where protection is needed, rather than uniformly across all surfaces as would occur with conventional sputtering.
Solution Approach 2:
The patent applies parameter changes by transitioning from sputtering to PECVD deposition methodology, and by using a collimator to alter the deposition geometry. These parameter changes fundamentally alter the deposition pattern from the thicker-at-upper-corners profile to a concentrated-at-bottom profile, enabling selective protection.
3Quantity of substance
If a conformal nitride layer is deposited using thermal CVD, then deposition is achieved, but the nitride layer deposits equally on sidewalls and bottom, preventing selective protection of lower corners
Solution Approach 1:
The patent overcomes the conformal deposition limitation by introducing a collimator in the PECVD process. This creates a densified nitride layer with highly non-uniform distribution, concentrating the material at the bottom of the opening while minimizing sidewall deposition, thus achieving the desired selective protection.
4Ease of manufacture
If field isolation regions are formed with liner layer and insulating layer, then device isolation is achieved, but stress during thermal cycles causes electrical defects and delamination
Solution Approach 1:
The patent implements preliminary action by forming the densified nitride layer at the bottom of the opening before completing the field isolation structure. This pre-established protective layer is in place to counteract the stress that will later be exerted by the field isolation regions during thermal cycles, preventing delamination and electrical defects.
Solution Approach 2:
The patent applies beforehand cushioning by creating the densified nitride layer as a protective buffer at the bottom of the opening before the field isolation regions are fully formed. This layer acts as a cushion that absorbs and distributes the stress from the field isolation regions during subsequent thermal cycles, preventing harmful effects on the semiconductor layer.
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 reduces corner rounding and stress on semiconductor layers, improving electrical performance and preventing delamination, while maintaining the integrity of the gate dielectric layer.
Implementation Method 1
depositing a nitride layer within the opening, wherein depositing is performed using a PECVD technique
Implementation Method 2
densifying the nitride layer
Data Source
AI summary
A process of forming an electronic device can include patterning a semiconductor layer to define an opening extending to an insulating layer, wherein the insulating layer lies between a substrate and the semiconductor layer. After patterning the semiconductor layer, the opening can have a bottom, and the semiconductor layer can have a sidewall and a surface. The surface can be spaced apart from the insulating layer, and the sidewall can extend from the surface towards the insulating layer. The process can also include depositing a nitride layer within the opening, wherein depositing is performed using a PECVD technique. The process can further include densifying the nitride layer. The process can still further include removing a part of the nitride layer, wherein a remaining portion of the nitride layer can lie within the opening and be spaced apart from the surface.