Bit Line Contact Structure Pickling With Sidewall Protection
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Solution Overview
Problem
In existing memory device processes, the pickling solutions used to reduce contact resistance between polysilicon and active areas also erode the shallow trench isolation structure and cause misalignment of bit line contact structures, leading to poor contact effects and device performance issues.
Innovation Solution
A manufacturing method for a semiconductor structure that involves forming a protective layer on the sidewalls of grooves or holes, removing the protective layer from the bottom, performing pickling to remove native oxides while retaining the protective layer on the sidewalls, and subsequently forming bit line structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pickling solution is used to remove native oxide on active area surface, then contact resistance between polysilicon and active area is reduced, but the shallow trench isolation structure is eroded and bit line contact structure alignment is shifted
Solution Approach 1:
The protective layer is selectively removed only from the bottom of grooves or holes where contact is needed, while retaining it on the sidewalls. This segmentation allows pickling to occur only in specific areas (bottom surfaces) without affecting the overall structure, thus removing native oxide for low contact resistance while protecting the shallow trench isolation structure and maintaining alignment precision.
Solution Approach 2:
A protective layer is introduced as an intermediary substance between the pickling solution and the shallow trench isolation structure. This protective layer acts as a barrier that prevents the pickling solution from eroding the isolation structure and causing alignment shifts, while still allowing the pickling process to effectively remove native oxide from the active area surface where contact is required.
2Reliability
If pickling solution is used to remove native oxide, then contact resistance is reduced, but erosion of shallow trench isolation structure occurs
Solution Approach 1:
The protective layer serves as an intermediary barrier that shields the shallow trench isolation structure from the harmful erosive effects of the pickling solution. By selectively removing the protective layer only at the bottom of grooves or holes, the invention allows the pickling solution to contact and remove native oxide from the active area surface (reducing contact resistance) while the retained protective layer on sidewalls prevents erosion of the isolation structure.
Solution Approach 2:
The protective layer is applied with spatially varying properties: it is completely removed from the bottom surfaces of grooves or holes where contact is needed, but retained on the sidewalls where protection is needed. This local differentiation allows the pickling process to achieve low contact resistance at contact points while preventing structure erosion in protected areas.
3Manufacturing precision
If bit line contact structure is shifted in alignment, then contact effect between contact structure and active area deteriorates
Solution Approach 1:
The protective layer is formed and selectively removed before the pickling process and subsequent contact structure formation. This preliminary preparation ensures that when the bit line contact structure is later formed, the underlying active area surface is already properly prepared (native oxide removed) and the protective layer on sidewalls is in place to prevent any alignment-related erosion, thus ensuring good contact effect even if minor alignment shifts occur.
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 ensures effective contact between the bit line structures and active areas, improves device performance by preventing erosion of the shallow trench isolation structure, and alleviates issues of voids and leakage current.
Implementation Method 1
performing pickling to remove a native oxide on a surface of each of the active areas exposed at the bottom of the grooves or holes
Data Source
AI summary
The present disclosure provides a manufacturing method of a semiconductor structure, and a semiconductor structure. The method includes: providing a substrate, where the substrate has active areas, and grooves or holes each for connecting a bit line structure to the active area are formed on a surface of the substrate; forming a protective layer, where the protective layer covers a bottom and a sidewall of each of the grooves or holes; removing the protective layer located at the bottom of each of the grooves or holes; performing pickling to remove a native oxide on a surface of each of the active areas exposed at the bottom of the grooves or holes, where partial protective layer is retained on the sidewall of each of the grooves or holes after pickling; and forming bit line structures.