CMP Pad Conditioning System Using Rotatable Bulk Material
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Solution Overview
Problem
The semiconductor industry faces inefficiencies in polishing pad conditioning, as existing CMP machines require significant downtime and waste resources when used to condition new pads, leading to scratching defects on wafers due to the pad's small asperity radius of curvature.
Innovation Solution
A dedicated polishing pad conditioning system with rotatable platens supporting polishing pads and bulk material, applying pressure and a slurry to increase the asperity radius of curvature, reducing conditioning time and eliminating the need for wafer usage, utilizing a slurry of 95% water and 5% ceramic particles, and incorporating cooling to manage heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CMP machine is used to condition a new polishing pad by polishing Cu-coated wafers, then the pad conditioning is achieved, but the machine experiences four hours of downtime and consumes valuable wafers and slurry
Solution Approach 1:
The patent extracts the pad conditioning function from the CMP machine by introducing a separate conditioning platen with bulk material. This dedicated conditioning mechanism can be attached to or integrated with the CMP machine, allowing pad conditioning to occur independently without occupying the main polishing machine time, thus resolving the contradiction between achieving reliable pad conditioning and maintaining high machine productivity
Solution Approach 2:
The conditioning platen serves multiple functions: it conditions the polishing pad by increasing asperity radius of curvature, it can be made from various materials (metal, ceramic, polymer) depending on the application, and it integrates with existing CMP infrastructure. This multi-functionality allows the same system to serve both conditioning and polishing operations without conflict
2Manufacturing precision
If the CMP machine is used to condition the polishing pad, then the pad asperity radius of curvature is increased, but four hours of machine time is lost
Solution Approach 1:
The patent enables preliminary pad conditioning to occur during normal polishing operations or in between wafers, rather than requiring a separate four-hour conditioning cycle. The conditioning platen works continuously or periodically to maintain optimal asperity radius of curvature, so the pad is always ready for polishing without requiring dedicated conditioning time
Solution Approach 2:
The conditioning platen enables continuous or near-continuous pad conditioning during polishing operations. Instead of interrupting the polishing process for four-hour conditioning cycles, the system maintains optimal pad conditions continuously through the rotating bulk material that constantly reconditions the pad surface, eliminating time loss while maintaining manufacturing precision
3Reliability
If traditional pad conditioning using CMP machine is used, then pad conditioning is achieved, but costly consumables (wafers and slurry) are wasted
Solution Approach 1:
The patent replaces the use of expensive Cu-coated wafers and environmentally harmful slurry with a reusable bulk material disk that can be made from inexpensive materials like metal, ceramic, or polymer. The bulk material is not consumed in the conditioning process and can be reused indefinitely, eliminating the need for disposable consumables while maintaining reliable pad conditioning quality
Solution Approach 2:
The conditioning system uses itself to condition the pad rather than requiring external consumables. The bulk material platen mechanically conditions the pad through friction and pressure during rotation, and any wear on the bulk material is minimal and reusable. The system essentially conditions the pad using its own operational mechanism without needing to consume separate materials, thereby eliminating waste of costly consumables
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 system significantly reduces pad conditioning time, minimizes waste, and allows continuous operation of CMP machines by increasing the asperity radius of curvature beyond the threshold, preventing scratching, and conserving resources by eliminating the need for environmentally harmful chemicals and costly consumables.
Implementation Method 1
a slurry containing a liquid and abrasive particles is pumped into the interface of the pad and the wafer to increase the material removal rate
Implementation Method 2
a machine is used to press a wafer and a polishing pad into contact at a selected pressure. Both the pad and the wafer are turned at a given rotational velocity
Implementation Method 3
cooling is provided to dissipate the heat from the conditioning process
Data Source
AI summary
Polishing pad conditioning system. The system includes a first rotatable platen supporting a polishing pad containing asperities having a radius of curvature. A second rotatable platen supports a disk of bulk material having holes therethrough, the second rotatable platen supported for translation as well as rotation. Means are provided for pushing the polishing pad and bulk material into contact at an interface during rotation and translation and means are provided for passing a slurry through the holes in the bulk material to the interface whereby the radius of curvature of the pad asperities is increased. Water may be delivered to the bulk material for cooling. A process for conditioning a polishing pad is also disclosed.