Polysilicon Dummy Stripe for CMP Dishing in Semiconductor Diodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of high voltage/middle voltage diodes with high-k metal gate technology in semiconductor manufacturing faces issues with metal residue left in unwanted recesses due to chemical mechanical polishing, leading to short circuits and diode malfunction.
Innovation Solution
Incorporating a dummy stripe structure within the diode region, formed from polysilicon, between the implant regions to prevent dishing during chemical mechanical polishing, ensuring the dummy gates are arranged with a maximum distance of 3.5 μm between them to effectively prevent concave surface profiles and metal residue accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing is performed to planarize the ILD layer surface, then surface flatness is improved, but dishing occurs in large implant regions creating unwanted recesses
Solution Approach 1:
Polysilicon stripes are formed in the diode region before the chemical mechanical polishing step. These pre-formed stripes act as placeholders that maintain surface profile during polishing, preventing the formation of unwanted recesses in the large implant regions. The stripes are removed after polishing completes its planarization function.
Solution Approach 2:
The polysilicon stripes serve as intermediary structures during the polishing process. They mediate between the polishing mechanism and the implant regions, distributing the polishing pressure and preventing direct excessive removal of material from the implant regions that would create dishing.
2Shape
If polysilicon stripes are formed in diode region to prevent dishing, then surface profile is maintained, but device structure becomes more complex
Solution Approach 1:
The polysilicon stripes are simple replicated structures formed by standard photolithography and deposition processes. They are essentially copies of a simple pattern that can be easily defined and removed, adding minimal complexity compared to redesigning the entire diode structure.
Solution Approach 2:
The polysilicon stripes are temporary structures that are formed, serve their purpose during polishing, and then completely removed. They are discarded after use, meaning they do not remain as permanent complexity in the final device structure. This temporary presence allows surface profile control without permanent structural complication.
3Reliability
If dummy stripe is added to prevent metal residue, then diode reliability is improved, but manufacturing process steps increase
Solution Approach 1:
The formation of polysilicon stripes is merged with existing diode fabrication process steps, particularly utilizing the same photolithography and deposition equipment and processes already required for other diode structures. This integration means the stripes are added without requiring entirely new process equipment or fundamentally different manufacturing approaches.
Solution Approach 2:
The polysilicon stripes serve multiple functions: they maintain surface profile during CMP, prevent dishing in implant regions, and prevent metal residue accumulation. This multi-functionality means a single structural addition addresses multiple potential failure modes, improving reliability without requiring separate process steps for each function.
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate, a diode region, and a dummy stripe. The substrate has a first surface. The diode region is in the substrate. The diode region includes a first implant region of a first conductivity type approximate to the first surface, and a second implant region of a second conductivity type approximate to the first surface and surrounded by the first implant region. The dummy stripe is on the first surface and located between the first implant region and the second implant region. A method for manufacturing a semiconductor structure is also provided.