Crescent Injector for CMP Slurry Delivery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Chemical Mechanical Polishing (CMP) processes face inefficiencies in slurry utilization, leading to significant waste and contamination, as most of the applied slurry is lost before reaching the wafer-pad interface, and residual wash water dilutes the slurry, affecting removal rates and uniformity.
Innovation Solution
A solid crescent shaped injector is used to introduce CMP slurry between the wafer and polishing pad in a thin film, matching the gap thickness, ensuring maximum slurry utilization and separating fresh from used slurry and wash water, reducing waste and improving process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If slurry is applied at constant flow rate onto the rotating polishing pad using simple delivery tube or nozzle, then slurry application is simple and device complexity is low, but slurry utilization is low and most slurry is lost before reaching the wafer-pad interface
Solution Approach 1:
A slurry delivery tube is introduced as an intermediary component that extends from the slurry source directly to the wafer-pad interface. The tube acts as a mediator to transport slurry along the wafer leading edge, ensuring slurry reaches the polishing zone efficiently without being lost to the pad periphery, thus reducing slurry waste while maintaining relatively simple device complexity
Solution Approach 2:
The slurry delivery tube is positioned to apply slurry preliminarily along the wafer leading edge before the wafer enters the main polishing zone. This preliminary action ensures that fresh slurry is already in place at the interface, improving slurry utilization by preventing the formation of bow waves and reducing the amount of slurry that would otherwise be lost
2Object-affected harmful factors
If deionized water is applied to wash used slurry off between wafers, then contamination is reduced, but residual water dilutes the newly added slurry causing decrease in removal rate and uniformity
Solution Approach 1:
The washing step is extracted and separated from the main polishing process. By removing used slurry with water before applying fresh slurry, the system prevents contamination while allowing complete evaporation or removal of residual water before the next polishing cycle, thus avoiding dilution effects and maintaining removal rate uniformity
Solution Approach 2:
The slurry delivery system maintains continuous application of fresh slurry along the wafer leading edge, ensuring that the polishing action is uninterrupted. This continuous supply compensates for any brief dilution effects from washing by immediately replenishing the slurry at the interface, maintaining consistent removal rates
3Ease of operation
If grooves are made in the CMP pad to facilitate slurry advection under the wafer, then some slurry reaches the pad-wafer interface, but most slurry is still cast off without being used and slurry consumption remains high
Solution Approach 1:
The slurry delivery tube serves as an intermediary that bypasses the need for complex pad grooves. It directly transports slurry to the wafer-pad interface, eliminating the reliance on pad surface features that fail to prevent slurry loss, thus reducing slurry consumption while maintaining ease of operation
Solution Approach 2:
The slurry delivery is segmented into discrete application points along the wafer leading edge through the delivery tube. This segmentation allows precise control of slurry placement, ensuring slurry is applied only where needed at the interface rather than being spread across the entire pad surface, reducing overall slurry consumption
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 significantly reduces slurry waste, ensures nearly 100% fresh slurry utilization, and maintains consistent slurry concentration, thereby enhancing removal rates and uniformity while minimizing the impact of residual wash water.
Implementation Method 1
CMP slurry or components thereof are introduced through one or more openings in the top of the injector and travel through a channel or reservoir the length of the device to the bottom where it or they exit multiple openings in the bottom of the injector
Implementation Method 2
a solid crescent shaped injector which rests on the pad with a light load, the bottom surface facing the pad
Data Source
AI summary
The present invention comprises an apparatus for injecting slurry between the wafer and the pad in chemical mechanical polishing of semiconductor wafers comprising a solid crescent shaped injector the concave trailing edge of which is fitted to the size and shape of the leading edge of the polishing head with a gap of up to 1 inch, the bottom surface of which faces the pad and rests on it with a light load, and through which CMP slurry or components thereof are introduced through one or more openings in the top of the injector and travel through a channel or reservoir the length of the device to the bottom where it or they exit multiple openings in the bottom of the injector, are spread into a thin film, and are introduced between the surface of the polishing pad and the wafer along the leading edge of the wafer in quantities such that all or most of the slurry is introduced between the wafer and the polishing pad and a method of use therefor.