Contact Plug Bottom Expansion Through Implantation-Controlled Etching
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Solution Overview
Problem
Conventional methods face challenges in achieving lateral expansion of bottom portions of contact plugs without deepening the openings, which can lead to corrosion of lower-level contact plugs during the formation of upper-level contact plugs in integrated circuit manufacturing.
Innovation Solution
An implantation process is performed to dope a dopant into the top portion of the lower contact plug, followed by forming a dielectric layer and recessing both vertically and laterally, increasing the lateral recessing rate relative to the vertical rate, thereby enlarging the bottom portion of the upper contact plug laterally more than vertically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lateral expansion of contact plug bottom portions is achieved through conventional methods, then the ability to block corrosive slurry is improved, but the openings become deeper which increases manufacturing complexity
Solution Approach 1:
The patent changes the etching parameters by introducing a dopant into the lower contact plug before etching, which modifies the etching rate characteristics. This allows selective lateral etching at the bottom portion while controlling overall etching depth, thereby achieving lateral expansion without proportionally increasing opening depth
Solution Approach 2:
The patent transitions from vertical expansion to lateral expansion by doping the bottom portion of the lower contact plug. This dimensional shift allows the upper contact plug to extend laterally at the bottom rather than vertically, blocking corrosive slurry without deepening the opening
2Manufacturing precision
If lateral expansion is achieved without dopant implantation, then the process is simpler, but the lateral recessing rate cannot be increased relative to vertical rate
Solution Approach 1:
The patent introduces dopant implantation as a parameter change that selectively modifies the etching characteristics of the lower contact plug. The dopant concentration and distribution are controlled to achieve differential etching rates between lateral and vertical directions, enabling precise lateral recessing
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 enhances the ability of the upper contact plug to block corrosive slurry, reducing the risk of corrosion to lower-level contact plugs by increasing lateral recessing without deepening the openings, thus improving the manufacturing process for integrated circuits.
Implementation Method 1
An implantation process is performed to dope a dopant into a top portion of the lower contact plug
Data Source
AI summary
A method includes forming a metallic feature, forming an etch stop layer over the metallic feature, implanting the metallic feature with a dopant, forming a dielectric layer over the etch stop layer, performing a first etching process to etch the dielectric layer and the etch stop layer to form a first opening, performing a second etching process to etch the metallic feature and to form a second opening in the metallic feature, wherein the second opening is joined with the first opening, and filling the first opening and the second opening with a metallic material to form a contact plug.