CMP Polishing Control for Copper Film Uniformity
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Solution Overview
Problem
The chemical mechanical polishing process in semiconductor manufacturing, particularly for dual damascene structures, faces issues of copper film thickness uniformity, leading to copper remaining on the wafer edge and over polishing/dishing, resulting in uneven electrical properties across the wafer.
Innovation Solution
A method is introduced to control the polishing process by measuring film average thickness distribution, determining a removal rate recipe based on this data, and adjusting pressure values and relative linear rates between the wafer and polishing pad, using a database to optimize the polishing process, ensuring uniformity and improving electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing process is performed on copper film, then planarization is achieved, but non-uniform thickness distribution occurs with copper remaining on wafer edge and over polishing at center
Solution Approach 1:
The patent applies different pressure values to different regions of the polishing head, creating localized polishing conditions. Specifically, higher pressure is applied to the center region and lower pressure to the edge region, allowing each area to be polished according to its specific thickness requirements, thus achieving uniform film thickness across the entire wafer surface
Solution Approach 2:
The patent dynamically adjusts polishing parameters including pressure distribution, relative linear rate between wafer and polishing pad, and polishing head rotation speed. These parameters are continuously optimized based on real-time measurements of film thickness distribution, enabling the system to adapt to varying film thickness conditions and achieve consistent polishing results
2Ease of operation
If uniform pressure is applied during polishing, then process simplicity is maintained, but non-uniform removal rate occurs leading to dishing and edge copper remaining
Solution Approach 1:
The patent implements non-uniform pressure distribution across the polishing head surface, with specifically designed pressure zones that apply higher pressure to areas requiring greater material removal (center regions) and lower pressure to areas requiring less removal (edge regions). This localized pressure control ensures uniform removal rate across the wafer while maintaining relatively simple process operation
Solution Approach 2:
The patent changes multiple polishing parameters simultaneously including pressure distribution pattern, relative linear rate, and polishing head rotation speed. By coordinating these parameter changes, the system achieves uniform removal rate without significantly increasing operational complexity, as all parameters are controlled through an integrated control system
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 ensures uniform film thickness and electrical properties across the wafer by controlling the polishing process parameters, addressing issues of copper remaining on the edge and over polishing/dishing, and allows for estimation of current removal rates to maintain consistency across different wafers.
Implementation Method 1
The chemical mechanical polishing process is widely applied on the method for forming a structure
Implementation Method 2
the copper film formed by using the electroplating process
Data Source
AI summary
The invention is directed to a method for controlling a polishing process. The method comprises steps of providing a first wafer, wherein a thin film is located over the first wafer. A film average thickness distribution is obtained by measuring a plurality of thickness values of the thin film on a plurality regions over the wafer respectively. A removal rate recipe is determined according to the film average thickness distribution. A polishing process is performed according to the removal rate recipe.