Composite Landing Pad for Semiconductor Interconnect Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The complexity of semiconductor device manufacturing leads to misalignment issues in interconnect structures, affecting device performance and yield rates due to the intricate integration of various functionalities in miniaturized semiconductor devices.
Innovation Solution
A method is developed to form a composite landing pad by creating a barrier layer and a lower metal plug surrounded by it, followed by a salicide process to form inner and outer silicide portions, which increases the landing area for upper metal plugs, reducing contact resistance and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional manufacturing processes are used for miniaturized semiconductor devices, then device integration and functionality are improved, but misalignment in interconnect structures occurs leading to reduced manufacturing precision
Solution Approach 1:
The patent applies preliminary action by forming a composite landing pad structure before the upper metal plug is deposited. The composite landing pad includes a lower metal plug, barrier layer, and silicide portions that are pre-formed to provide an enlarged target area. This preliminary structure ensures that even if the upper metal plug is misaligned during subsequent processing, it will still make proper contact with the lower metal plug, thereby preventing misalignment issues in the final interconnect structure.
Solution Approach 2:
The patent changes the physical parameters of the landing pad by transforming the lower metal plug and barrier layer into silicide compounds through a salicide process. This chemical transformation creates a composite structure with different electrical and mechanical properties, forming inner and outer silicide portions that provide both electrical connectivity and mechanical tolerance for alignment variations.
2Manufacturing precision
If the landing area for upper metal plugs is increased, then misalignment is reduced, but contact resistance may increase due to larger contact area
Solution Approach 1:
The patent employs composite materials by creating a multi-layered landing pad structure consisting of different materials: lower metal plug (e.g., tungsten), barrier layer (e.g., titanium nitride), and silicide portions (e.g., titanium silicide). Each material contributes specific properties - the lower metal plug provides mechanical strength, the barrier layer prevents diffusion, and the silicide portions provide low contact resistance. This composite structure allows the landing area to be enlarged while maintaining low contact resistance through the inherent properties of the silicide materials.
3Ease of manufacture
If a simple single-layer landing pad is used, then manufacturing is easier, but alignment tolerance is insufficient for miniaturized devices
Solution Approach 1:
The patent applies segmentation by dividing the landing pad into distinct functional segments: a lower metal plug segment, a barrier layer segment, and multiple silicide portions (inner and outer) segmented by their spatial locations. This segmentation allows each segment to be optimized for its specific function while collectively providing alignment tolerance. The segmented structure is formed through sequential processing steps, making the complex structure manageable and manufacturable.
Solution Approach 2:
The patent implements the nested doll principle by creating a concentric, multi-layered structure where the inner silicide portion is surrounded by the outer silicide portion, which in turn is surrounded by the barrier layer, and the entire structure is centered around the lower metal plug. This nested arrangement maximizes the use of vertical space and provides progressive layers of alignment tolerance, where each concentric layer acts as a buffer zone for potential misalignment.
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
The method improves device performance and increases yield rates by reducing contact resistance and preventing misalignment between lower and upper metal plugs, while also reducing associated costs through the salicide process.
Implementation Method 1
performing a salicide process to form an inner silicide portion over the first lower metal plug and an outer silicide portion over the barrier layer
Implementation Method 2
depositing a silicon layer over the first dielectric layer, the barrier layer and the first lower metal plug
Data Source
AI summary
The present disclosure relates to a method for preparing a semiconductor device with a composite landing pad. The method includes forming a first dielectric layer over a semiconductor substrate. The method also includes forming a barrier layer and a first lower metal plug penetrating through the first dielectric layer and in a cell region. The first lower metal plug is surrounded by the barrier layer. The method further includes depositing a silicon layer over the first dielectric layer, the barrier layer and the first lower metal plug. In addition, the method includes performing a salicide process to form an inner silicide portion over the first lower metal plug and an outer silicide portion over the barrier layer after the silicon layer is formed. The inner silicide portion is surrounded by the outer silicide portion, and a recess is formed over the inner silicide portion.