Wafer Cutting Using Plasma Etching and Tensile Tape Separation
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Solution Overview
Problem
Conventional wafer cutting methods, such as etching and laser cutting, are inefficient and can damage the wafer or reduce the strength of semiconductor chips, with the laser cutting process generating high heat and requiring additional costly steps like etching mask formation and removal.
Innovation Solution
A method involving a supporting member on the wafer's upper surface, with plasma-etching and tensile tape to reduce wafer thickness and separate semiconductor chips without an etching mask, using laser cutting and tensile tape with different tensile modules to minimize heat damage and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If laser cutting process is used to cut wafer without etching mask, then cutting time and cost are reduced, but high heat generated damages the wafer and reduces semiconductor chip strength
Solution Approach 1:
The cutting process is divided into two distinct stages: first laser cutting to separate chips quickly, then plasma etching to repair damage. This segmentation allows each process to optimize for its specific function - speed for laser, quality for plasma
Solution Approach 2:
The harmful heat damage from laser cutting is converted into a beneficial opportunity by applying plasma etching that selectively removes damaged material while reinforcing healthy areas, ultimately improving chip strength beyond the original state
2Manufacturing precision
If conventional etching process with etching mask is used to cut wafer, then cutting precision is improved, but additional processes for mask formation and removal increase cost and time
Solution Approach 1:
The etching mask step is completely extracted and removed from the process flow. Plasma etching is used directly on the wafer surface without requiring mask formation, mask alignment, or mask removal steps, dramatically simplifying the overall process
Solution Approach 2:
The plasma etching process inherently provides self-alignment and self-limiting characteristics, automatically etching only where needed based on wafer geometry and process parameters, eliminating the need for external mask guidance
3Strength
If wafer is plasma-etched to reduce thickness, then wafer strength is improved and damage is minimized, but additional process time is required
Solution Approach 1:
The plasma etching process simultaneously achieves multiple objectives: thickness reduction, damage repair, and strength enhancement in a single integrated step, eliminating the need for separate reinforcement processes
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 method reduces wafer cutting costs and time, minimizes damage to the wafer, and maintains the strength of semiconductor chips by plasma-etching without an etching mask and using cooled tensile tape to separate chips efficiently.
Implementation Method 1
a laser beam is irradiated to cut through the wafer along a scribe lane of the wafer
Implementation Method 2
the lower surface of the wafer is plasma-etched to reduce a thickness of the wafer
Implementation Method 3
The tensile tape is cooled to increase the tensile modules between the tensile films
Data Source
AI summary
In a method of cutting a wafer, a supporting member is attached to an upper surface of the wafer on which semiconductor chips are formed. An opening is formed at a lower surface of the wafer along a scribe lane of the wafer. The lower surface of the wafer may be plasma-etched to reduce a thickness of the wafer. A tensile tape may be attached to the lower surface of the wafer. Here, the tensile tape includes sequentially stacked tensile films having different tensile modules. The supporting member is then removed. The tensile tape is cooled to increase the tensile modules between the tensile films. The tensile tape is tensed until the tensile films are cut using the tensile modules difference to separate the tensile tape from the semiconductor chips. Thus, the lower surface of the wafer may be plasma-etched without using an etching mask.