Pad Conditioning Disk Gimbal Control via Electromagnetic Biasing
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Solution Overview
Problem
Existing pad conditioning methods for chemical mechanical polishing (CMP) suffer from variations in pad conditioning due to gimbal bias, leading to sparse contact between the diamond disk and the pad, which reduces effective cut-rate and material removal uniformity.
Innovation Solution
A pad conditioning assembly with a gimbal control assembly that includes at least one electromagnet coupled to a conditioning head, allowing for localized biasing of the pad conditioning disk to optimize contact with the polishing pad, thereby improving cutting efficiency and compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pad conditioning methods are used, then the pad conditioning process is simple, but variations in pad conditioning occur due to gimbal bias, leading to sparse contact between the diamond disk and the pad
Solution Approach 1:
The patent applies local quality by implementing localized biasing through electromagnets positioned at specific locations around the conditioning head. This allows different regions of the pad conditioning disk to have tailored magnetic forces applied to them, compensating for gimbal bias variations across different areas of the pad surface, thereby achieving more uniform pad conditioning.
Solution Approach 2:
The patent replaces traditional mechanical gimbal bias adjustment mechanisms with an electromagnetic control system. Instead of mechanically adjusting the gimbal assembly to compensate for bias, electromagnets are used to generate magnetic forces that actively counteract gimbal bias effects, providing a more precise and controllable solution.
2Productivity
If gimbal bias is present, then the device structure remains simple, but the effective cut-rate and material removal uniformity are reduced
Solution Approach 1:
The patent implements feedback control by using sensors to detect the actual contact conditions between the pad conditioning disk and the pad, then using this information to adjust the electromagnet currents. This closed-loop control system continuously compensates for gimbal bias variations, ensuring consistent material removal uniformity and maintaining optimal cut-rate across the entire pad surface.
Solution Approach 2:
The patent changes the electromagnetic parameters (current magnitude and distribution) of the electromagnets to compensate for gimbal bias. By dynamically adjusting the magnetic field strength and distribution, the system optimizes the contact pressure and diamond-to-pad contact area, thereby improving both material removal rate and uniformity.
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 solution enables more effective and uniform conditioning of the polishing pad, enhancing material removal across the substrate surface and improving CMP performance by maximizing diamond contact area and conforming to the pad surface.
Implementation Method 1
at least one electromagnet coupled to the conditioning head
Data Source
AI summary
Embodiments of the disclosure provided herein include a system and method for pad conditioning in chemical mechanical polishing. In an embodiment, a pad conditioning assembly includes a base, an arm coupled to the base, a conditioning head coupled to the arm, a gimbal control assembly including at least one electromagnet coupled to the conditioning head, a gimbal flexure configured to couple to a pad conditioning disk, and a gimbal control feature coupled to the gimbal flexure, and a controller configured to control operation of the pad conditioning assembly. In another embodiment, a method of conditioning a pad for chemical mechanical polishing includes initiating conditioning of a pad on a platen using a pad conditioning assembly, determining if a distance exceeds a predetermined threshold, and biasing a pad conditioning disk of the pad conditioning assembly.