Stationary Ring Inclination Control in CMP Polishing
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is to accurately control the polishing profile of the edge portion of substrates during chemical mechanical polishing (CMP), as the inclination angle of the retainer ring significantly affects the polishing outcome, and existing technologies lack precise control mechanisms.
Innovation Solution
A polishing apparatus with a rotatable head body, a retainer ring, a rotational ring, a stationary ring, and local load applying devices, along with displacement sensors and actuators, calculates and adjusts the inclination angle of the stationary ring to control the retainer ring's inclination, ensuring precise polishing profile management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the retainer ring is used to control the polishing profile of the edge portion, then the polishing profile can be controlled, but the inclination angle of the retainer ring cannot be accurately controlled
Solution Approach 1:
The patent implements a feedback control system where displacement sensors continuously measure the actual inclination angle of the retainer ring, and the controller adjusts the local load applying devices to correct any deviation from the target inclination angle. This closed-loop feedback mechanism ensures accurate inclination angle control despite variations in polishing conditions.
Solution Approach 2:
The patent replaces direct mechanical inclination adjustment mechanisms with a combination of local load applying devices and displacement sensors. Instead of mechanically tilting the retainer ring, the system uses controlled local loads to achieve the desired inclination, with the actual angle being measured and controlled through sensor feedback rather than pure mechanical positioning.
2Manufacturing precision
If local load is applied to tilt the retainer ring, then the polishing profile of the edge portion can be positively controlled, but the inclination angle becomes difficult to control accurately
Solution Approach 1:
The displacement sensors provide real-time feedback on the retainer ring's inclination angle, allowing the controller to automatically adjust the local load distribution. This eliminates the need for manual inclination adjustment and ensures precise control of the polishing profile through automated feedback-based load management.
Solution Approach 2:
The system controls the polishing profile by dynamically changing the local load parameters applied to the retainer ring. Instead of fixing the inclination angle mechanically, the system adjusts the magnitude and distribution of local loads to achieve and maintain the desired inclination angle and polishing profile throughout the polishing process.
3Reliability
If the retainer ring presses the polishing pad around the substrate, then the substrate is prevented from detaching, but the polishing profile of the edge portion deteriorates
Solution Approach 1:
The patent applies local load to specific portions of the retainer ring rather than uniform loading. This creates different functional zones: the majority of the retainer ring maintains sufficient pressing force for substrate retention, while the locally loaded portion creates the necessary inclination to control the edge portion polishing profile. This local differentiation resolves the contradiction between retention and profile control.
Solution Approach 2:
The retainer ring's loading is segmented into different regions with different load characteristics. The local load applying devices create segmented loading zones that independently control substrate retention and edge profile polishing, allowing both functions to operate optimally without interfering with each other.
Data Source
AI summary
A polishing apparatus includes a rotatable head body having a pressing surface, a retainer ring configured to press a polishing surface while rotating together with the head body, a stationary ring, local load applying devices configured to apply a local load to the stationary ring, and a controller. The local load applying devices include a first pressing member and a second pressing member connected to the stationary ring. The first pressing member is disposed in the upstream side of the retainer ring in the traveling direction of the polishing surface, and the second pressing member is disposed in the downstream side. The controller calculates the inclination angle of the stationary ring based on a measured value of the height of at least one of the first pressing member and the second pressing member.