Semiconductor Metal Nitride Layer CMP Uniformity
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes for metals in semiconductor manufacturing face issues such as dishing, recess, and non-uniformities, which affect product yield and performance due to the sensitivity of metal thickness, especially as scaling advances.
Innovation Solution
A method involving a preliminary semiconductor structure with varying trench widths, a tungsten metal layer, and a nitrogen treatment to form a metal nitride layer, which is then planarized to improve CMP uniformity by enhancing the hardness of the concave portions, particularly in wider trenches, thereby addressing dishing and recess issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a CMP process is performed on metals to planarize the surface, then the surface flatness is improved, but dishing, recess, and erosion occur causing non-uniformities
Solution Approach 1:
The patent changes the material parameter of the metal layer by converting it to a metal nitride layer through nitrogen plasma treatment. This parameter change transforms the soft metal into a harder nitride compound, fundamentally altering the removal characteristics during CMP to achieve uniform planarization without dishing or recess.
Solution Approach 2:
The patent uses nitrogen plasma as a reactive environment to accelerate the formation of metal nitride on the metal layer surface. The high-energy nitrogen species in the plasma rapidly react with the metal to form a uniform nitride layer before CMP, ensuring consistent hardness and removal rate across the entire surface.
2Productivity
If the metal layer is made thinner to continue scaling, then device density is improved, but CMP non-uniformities become more detrimental affecting yield and performance
Solution Approach 1:
The patent applies nitrogen plasma treatment to transform the metal layer into a metal nitride layer with enhanced hardness and uniform removal characteristics. This parameter change enables CMP processes to achieve better uniformity even on thinner metal layers, supporting continued device scaling while maintaining manufacturing precision.
3Adaptability or versatility
If a wider trench is formed in the second region, then the structural design flexibility is improved, but dishing and recess issues are exacerbated in that region
Solution Approach 1:
The patent uses nitrogen plasma treatment to uniformly convert the metal layer across different trench widths into a metal nitride layer. This parameter change equalizes the hardness and removal rate across both narrow and wide trenches, eliminating the dishing and recess problems that typically occur in wider regions during CMP.
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 achieves better CMP results and planar uniformity by utilizing the greater hardness of the metal nitride layer, improving product yields and performance by ensuring consistent removal rates across different trench regions.
Implementation Method 1
forming a metal nitride layer on the metal layer by an nitride treatment
Implementation Method 2
Chemical mechanical polishing (CMP) is widely and increasingly used in integrated circuit (IC) manufacturing as a method of removing material to enable the planarization of a surface
Data Source
AI summary
A method of manufacturing a semiconductor structure, comprising: providing a preliminary structure having a first region and a second region and comprising a plurality of first trenches in the first region; forming a metal layer filling the first trenches covering on the preliminary structure, wherein the metal layer comprises a concave portion in the second region and the concave portion defines an opening; forming a metal nitride layer on the metal layer by an nitride treatment; and performing a planarization process to remove the metal nitride layer and a portion of the metal layer to expose the preliminary structure.