Mask Removal via Alkaline Dissolution for Semiconductor Dicing
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Solution Overview
Problem
In element chip manufacturing, ashing failures occur due to insufficient mask removal during plasma dicing, particularly for sensitive components like CMOS image sensors, leading to reduced productivity and potential damage from ultraviolet exposure.
Innovation Solution
A method involving the formation of a plasma-resistant mask on the substrate, followed by its removal using alkaline chemicals with a higher dissolution rate than the adhesive layer, ensuring complete mask removal without damaging the chip and improving productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mask removal is performed with conventional methods, then mask removal is achieved, but ashing failures occur and productivity decreases
Solution Approach 1:
The patent changes the chemical parameters of the mask by using alkaline chemicals with controlled dissolution rates. The mask is designed to have a dissolution rate greater than the adhesive layer in alkaline conditions, enabling selective removal. This parameter change allows complete mask removal without ashing failures, improving both productivity and reliability.
Solution Approach 2:
The patent replaces the mechanical/thermal ashing process with a chemical dissolution process. Instead of using plasma or heat to remove the mask, alkaline chemicals are used to dissolve it selectively. This substitution eliminates ashing failures and improves productivity by providing a more reliable and efficient removal mechanism.
2Reliability
If mask is removed completely, then ashing failures are suppressed, but adhesive layer may be damaged
Solution Approach 1:
The patent applies local quality by creating different dissolution rate characteristics in different layers. The mask is formulated to have a higher dissolution rate than the adhesive layer when exposed to alkaline chemicals. This local differentiation in chemical resistance allows complete mask removal while preserving the adhesive layer, preventing both ashing failures and adhesive damage.
Solution Approach 2:
The patent provides beforehand cushioning by designing the mask with controlled dissolution characteristics that prevent excessive chemical attack on the adhesive layer. The mask acts as a protective buffer that dissolves first, shielding the adhesive layer from direct exposure to harsh removal conditions. This pre-designed dissolution hierarchy ensures complete mask removal while maintaining adhesive integrity.
3Ease of manufacture
If conventional ashing is used, then mask removal is attempted, but sensitive components like CMOS image sensors are damaged by ultraviolet exposure
Solution Approach 1:
The patent substitutes the ultraviolet-based plasma ashing process with a chemical dissolution process using alkaline chemicals. This replacement eliminates the harmful ultraviolet radiation that damages sensitive components like CMOS image sensors, while still achieving complete mask removal. The chemical process is gentler and more suitable for devices with UV-sensitive elements.
Solution Approach 2:
The patent converts the potential harm of aggressive mask removal into a benefit by using selective chemical dissolution. The alkaline chemicals provide controlled, selective removal that protects sensitive components while effectively removing the mask. This approach turns the challenge of complete mask removal without damage into an advantage, enabling safe processing of UV-sensitive devices.
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 approach effectively suppresses ashing failures, enhances productivity by ensuring complete mask removal, and reduces damage to the element chips during the process, particularly for sensitive components.
Implementation Method 1
the mask is removed from the plurality of element chips with alkaline chemicals having a dissolution rate of the mask greater than a dissolution rate of the adhesive layer
Implementation Method 2
holding a second face by a holding sheet via an adhesive layer
Implementation Method 3
singulating the substrate into a plurality of element chips by etching the substrate exposed to the opening with a first plasma
Data Source
AI summary
A semiconductor chip manufacturing method includes forming a mask on a surface of a semiconductor wafer, forming an opening on the mask, exposing a dividing region of the semiconductor wafer, a rear surface of the semiconductor wafer is held by a dicing tape via an adhesive layer, singulating the semiconductor wafer into a plurality of semiconductor chips by etching the semiconductor wafer exposed to the opening with a first plasma until the semiconductor wafer reaches a rear surface, removing the mask so that the plurality of element chips from which the mask is removed are held by the holding sheet via the adhesive layer.At the time of removing the mask, the mask is removed from an alkaline developer having a dissolution rate of the mask larger than a dissolution rate of the adhesive layer.