CMP Carrier Pressure Zones for Planar Surface Control
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Solution Overview
Problem
Conventional chemical mechanical planarization (CMP) processes face challenges in controlling pressure distribution across work pieces, leading to non-planar surfaces and over-correction issues due to inadequate control of adjustable pressure zones.
Innovation Solution
Implementing a closed-loop control method using a multiprobe thickness-measuring system to adjust and control pressures within multiple zones of a work piece carrier during CMP, allowing for real-time monitoring and adjustment to achieve a substantially planar or target non-planar profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional carriers with pressure zones are used during CMP, then material removal occurs across the work piece surface, but the pressure distribution is not sufficiently controllable resulting in non-planar surface profiles
Solution Approach 1:
The carrier is divided into multiple independently controllable pressure zones (first, second, and third pressure zones) with separate pressure control systems. This segmentation allows independent adjustment of pressure in each zone to achieve uniform material removal and planar surface profiles, resolving the issue of insufficient pressure controllability in conventional single-zone carriers.
Solution Approach 2:
Different pressure values are applied to different zones of the carrier based on the local requirements of the work piece surface. The pressure control system adjusts pressure distribution locally across the carrier surface to compensate for non-uniform material removal, thereby achieving planar surfaces while maintaining precise pressure control.
2Manufacturing precision
If pressure adjustments are made during CMP process, then surface planarity can be improved, but adjustments typically occur toward the end resulting in over-correction
Solution Approach 1:
A feedback control system continuously monitors the surface profile of the work piece during the CMP process and automatically adjusts the pressure distribution across the carrier zones in real-time. This closed-loop feedback mechanism enables timely pressure adjustments throughout the process rather than only at the end, preventing over-correction while achieving planar surfaces.
Solution Approach 2:
The multi-zone pressure control system is configured to make preliminary pressure adjustments at the beginning and middle stages of the CMP process based on predetermined pressure profiles. This preliminary action prevents the need for large corrective adjustments at the end of the process, avoiding over-correction while maintaining surface planarity.
Data Source
AI summary
Methods are provided for controlling adjustable pressure zones of a CMP carrier. A method comprises determining a first thickness of a layer on a wafer underlying a first zone of the carrier. A first portion of the layer underlying the first zone is removed. The first zone is configured to exert a first pressure against the second surface of the wafer. A second thickness of the layer underlying the first zone is determined and a target thickness corresponding to a predetermined thickness profile is selected. A second pressure for the first zone is calculated using the first thickness, the second thickness, the first pressure, and the target thickness. The pressure exerted by the first zone against the second surface of the wafer is adjusted to the second pressure and the steps are repeated for a second zone.