Polishing Apparatus Substrate Escape Detection
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Solution Overview
Problem
The challenge is to detect substrate escape from a top ring during polishing without causing photocorrosion of copper layers on semiconductor wafers, as conventional methods involving light irradiation can lead to copper corrosion.
Innovation Solution
A polishing apparatus with a substrate escape detection section that minimizes light irradiation time by using a light irradiation member and a controller to control light exposure only when the substrate is in contact with the polishing pad, and includes a light-shielding housing to prevent external light exposure, ensuring secure detection of substrate escape without inducing photocorrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light irradiation methods are used to detect substrate escape, then substrate escape detection capability is improved, but copper layer photocorrosion occurs
Solution Approach 1:
The light source is activated periodically only during the substrate transfer phase when the substrate is not in contact with the polishing pad, and deactivated during polishing when the substrate is in contact with the pad. This periodic activation pattern enables escape detection while preventing photocorrosion of the copper layer during the polishing operation.
Solution Approach 2:
The system uses the polishing pad as an intermediary to control light exposure. When the substrate contacts the polishing pad, the pad physically blocks light from reaching the substrate surface, thereby preventing photocorrosion while allowing the optical detection system to monitor for escape conditions through other optical paths.
2Reliability
If continuous light irradiation is used for escape detection, then detection reliability is improved, but photocorrosion risk increases
Solution Approach 1:
The light source operates in periodic cycles - activated during substrate loading and transfer when detection is needed, and deactivated during polishing when the substrate is protected by the polishing pad. This periodic operation maintains detection reliability for critical phases while eliminating photocorrosion risk during polishing.
Solution Approach 2:
The system performs preliminary detection actions during substrate transfer before polishing begins. By detecting potential escape conditions during the transfer phase when light is active, the system prevents the need for continuous light irradiation during polishing, thereby maintaining reliability while preventing photocorrosion.
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 solution effectively prevents photocorrosion of copper layers by limiting light exposure to the substrate, securely detecting escape from the top ring throughout the polishing process, thereby preventing substrate breakage and apparatus damage.
Implementation Method 1
a light irradiation member for irradiating an area of an upper surface of the polishing pad with light
Implementation Method 2
a light-receiving member for taking in a reflected light of the irradiating light or an image-taking member for taking an image of the area irradiated with the light
Data Source
AI summary
A polishing apparatus detects the escape of a substrate from a top ring during polishing. The polishing apparatus includes a polishing table having a polishing pad, a top ring, and a substrate escape detection section for detecting escape of the substrate from the top ring. The detection section includes a light irradiation member for irradiating an area of the upper surface of the polishing pad with light, a controller for controlling the light irradiation of the light irradiation member, an image-taking member for taking an image of the area irradiated with the light, and an information processing member for processing information outputted from the image-taking member. The controller controls the light irradiation member in such a manner that it performs light irradiation at least for a period of time during which the substrate is regarded as being in contact with the polishing pad.