Electrostatic Chuck Asperities Prevent Tape Burning
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Solution Overview
Problem
In plasma etching processes, bubbles can form between the tape and the electrostatic chuck, leading to tape burning due to inadequate cooling and contact issues, which compromises the adhesion and integrity of the tape during processing.
Innovation Solution
The electrostatic chuck features a disk-shaped member with fine holes and asperities on its surface, connected to a vacuum source, which creates a suction passage to ensure the tape is in constant contact, preventing bubble formation and subsequent tape burning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wafer is held on the electrostatic chuck using suction through fine holes, then the wafer can be securely positioned, but bubbles may form between the tape and the chuck surface, leading to inadequate cooling and tape burning
Solution Approach 1:
The asperities are formed on the holding surface in advance before the wafer is mounted. These pre-formed asperities create suction passages that actively draw out air and prevent bubble formation during the wafer holding process, thereby preventing tape burning before it can occur
Solution Approach 2:
The holding surface is designed with asperities that create a porous-like structure with multiple small suction passages. This porous structure allows air to be efficiently evacuated from between the tape and chuck surface, preventing bubble formation while maintaining secure wafer holding
2Strength
If the holding surface is made smooth to improve wafer contact, then adhesion is enhanced, but bubbles are more likely to form and trap air, causing tape burning
Solution Approach 1:
The holding surface is designed with local variations in roughness - asperities are distributed across the surface to create localized suction passages. This local quality approach allows the surface to maintain overall smoothness for good adhesion while having specific localized regions that actively prevent bubble formation through suction
Solution Approach 2:
The asperities create a pneumatic effect by forming suction passages that actively evacuate air from between the tape and chuck. This pneumatic action prevents bubble formation while the overall surface topology maintains adequate contact for strong adhesion
3Ease of manufacture
If the number of fine holes is reduced to lower manufacturing costs, then manufacturing becomes simpler, but bubble suppression capability is weakened
Solution Approach 1:
Instead of relying on a large number of fine holes, the solution segments the suction function into multiple asperities distributed across the holding surface. Each asperity creates its own suction passage, and collectively they provide comprehensive bubble suppression coverage without requiring numerous fine holes
Solution Approach 2:
The invention changes the parameter of surface topology from a flat surface with fine holes to an asperity-rich surface. This parameter change transforms the suction mechanism from hole-based to surface-geometry-based, reducing manufacturing complexity while maintaining or improving bubble suppression capability
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 configuration effectively suppresses bubble generation between the tape and the chuck, preventing tape burning and ensuring stable adhesion during plasma etching, without increasing manufacturing costs by reducing the number of fine holes.
Implementation Method 1
when the vacuum source is operated to produce a vacuum on the holding surface through the fine holes and thereby hold the wafer through the tape on the holding surface under suction
Implementation Method 2
the asperities formed on the holding surface function as a suction passage communicating with the fine holes
Implementation Method 3
The electrostatic chuck is formed with a cooling water passage for passing a cooling water to remove the reaction heat generated by the reaction between the etching gas (plasma) and the wafer
Data Source
AI summary
An electrostatic chuck is provided and has a holding surface for holding a wafer with a tape attached to one side of the wafer where the tape is in contact with the holding surface. The electrostatic chuck includes a disk-shaped member having a plurality of fine holes communicating with a vacuum source, where the fine holes are exposed to the holding surface. The disk-shaped member also includes a plurality of asperities formed on the holding surface and connected to the fine holes, and an electrode embedded in the disk-shaped member. The vacuum source is operated to produce a vacuum on the holding surface through the fine holes and thereby hold the wafer through the tape on the holding surface under suction, where the asperities formed on the holding surface function as a suction passage communicating with the fine holes.