Semiconductor Package Debris-Free Singulation via Backside Plasma Etch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional singulation processes of wafers with backside metallization (BSM) result in metal debris on semiconductor packages, leading to reliability issues such as short circuiting.
Innovation Solution
A method involving etching the wafer from the backside to singulate dies, avoiding metal debris on the sides, and using a combination of passivation layers and backside metallization to create a semiconductor package with specific sidewall profiles that prevent debris accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional singulation process is used on wafer with backside metallization, then dies can be separated, but metal debris remains on package sides causing reliability issues
Solution Approach 1:
The patent applies preliminary action by forming a protective coating on the backside metallization before the singulation process. This coating prevents metal debris from being generated during etching, thereby maintaining both high productivity and reliability without requiring additional debris removal steps.
Solution Approach 2:
The patent converts the potentially harmful metal debris into a beneficial situation by using the backside metallization as an etch stop layer. The metallization layer, which would normally create debris, now serves to define the etch depth and protect underlying structures, transforming the problem into a solution that enhances precision.
2Manufacturing precision
If wafer is thinned to improve circuit performance, then electrical performance improves, but mechanical strength decreases
Solution Approach 1:
The patent uses composite materials by combining the thinned wafer substrate with backside metallization layers and passivation structures. This composite structure provides both the thinness required for electrical performance and the mechanical strength needed for handling, as the metallization and passivation layers compensate for the reduced substrate thickness.
Solution Approach 2:
The patent applies local quality by maintaining different thicknesses in different regions - the active circuit areas are thinned for performance, while the edge regions and areas with backside metallization retain sufficient thickness for mechanical strength. This localized approach allows simultaneous optimization of electrical and mechanical properties.
3Reliability
If backside metallization is added to improve electrical and thermal performance, then package performance improves, but debris generation during singulation increases
Solution Approach 1:
The patent introduces an intermediary protective coating between the backside metallization and the etching process. This coating acts as a mediator that allows the etching to proceed cleanly without directly contacting and fragmenting the metallization, thus preserving both the performance benefits of BSM and eliminating debris generation.
Solution Approach 2:
The patent replaces the mechanical dicing process with a chemical etching process that uses the backside metallization as an etch stop. This substitution eliminates the mechanical forces that generate debris, using instead a controlled chemical reaction that defines boundaries without physical contact and fragmentation.
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
The solution effectively eliminates metal debris, enhancing the reliability and yield of semiconductor packages by ensuring clean singulation and improved mechanical and thermal performance.
Implementation Method 1
etching the wafer from the back surface of the wafer to completely singulate the dies, wherein singulating the wafer into dies avoids metal debris on sides of the dies
Data Source
AI summary
A semiconductor package which is free of metal debris from backside metallization (BSM) is disclosed. The semiconductor package is singulated by performing a saw street open process from the frontside of the wafer and then includes a singulation process using a plasma etch from the backside of the wafer with BSM. The singulation process results in metal debris free packages.