Polyimide Passivation Film for Semiconductor Wafer Protection
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Solution Overview
Problem
Existing passivation films for semiconductor wafers fail to simultaneously provide electric insulation, heat-tolerance, solvent-tolerance, and dry etch back properties, with known materials like benzocyclobutene resins damaging wafers during dry etch back, polyimides causing thermal stress, and fully aromatic polyethers having low softening points and poor solvent resistance.
Innovation Solution
A composition comprising a polymer with specific unit structures, such as polyether ether ketone or polyether ether sulfone, which includes groups like sulfonyl, fluoroalkylene, or arylene, allowing for the formation of a passivation film with improved electrical insulation, heat-tolerance, solvent-tolerance, and dry etch back properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If benzocyclobutene resin is used for passivation film, then the film can be formed, but fluorine gas is required for dry etch back which damages electrodes and wafers
Solution Approach 1:
The patent changes the chemical composition parameters of the passivation film by using polyimide resin instead of benzocyclobutene resin, enabling dry etch back with oxygen-containing gas without requiring fluorine gas, thus eliminating damage to electrodes and wafers
Solution Approach 2:
The patent substitutes the chemical etching mechanism by replacing fluorine-based chemistry with oxygen-based chemistry, achieving the same dry etch back function without the harmful side effects of fluorine gas
2Temperature
If benzocyclobutene resin is used for passivation film, then the film can be formed, but cross-linking reaction does not sufficiently proceed at curing temperature around 200°C and good solvent-tolerance cannot be obtained
Solution Approach 1:
The patent changes the curing temperature parameter from around 200°C to 300°C or higher, which enables sufficient cross-linking reaction of the polyimide resin and achieves good solvent-tolerance and heat-tolerance properties
3Temperature
If polyimide is used for passivation film, then heat-tolerance can be achieved, but thinned wafers are damaged because film-forming temperature is 300°C or higher
Solution Approach 1:
The patent performs preliminary actions by forming the passivation film on the rear surface before wafer thinning, and by using a multi-layer structure with a lower-layer film that can be formed at lower temperature, thus protecting the wafer from high temperature damage while still achieving heat-tolerance
4Temperature
If polyimide is used for passivation film, then heat-tolerance can be achieved, but shrinkage of films upon curing results in remaining stresses
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the lower-layer film and upper-layer film have different properties, with the lower-layer film being formed at lower temperature and having different shrinkage characteristics, thus reducing overall remaining stresses while maintaining heat-tolerance
5Ease of manufacture
If fully aromatic polyether is used for passivation film, then the film can be formed, but resins have low softening points and are not highly tolerant of solvents
Solution Approach 1:
The patent changes the chemical composition parameter by using polyimide resin instead of fully aromatic polyether, and changes the curing temperature parameter to 300°C or higher, which enables sufficient cross-linking reaction and achieves high solvent-tolerance while maintaining ease of manufacture
6Ease of manufacture
If fully aromatic polyether is used for passivation film, then the film can be formed, but resins may be melted in joining electrodes
Solution Approach 1:
The patent changes the material parameter from fully aromatic polyether to polyimide resin, and changes the curing temperature parameter to 300°C or higher, which achieves sufficient cross-linking and raises the softening point, thus preventing resin melting during electrode joining while maintaining ease of manufacture
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 proposed composition enables the formation of a passivation film with excellent electric insulation, heat-tolerance, solvent-tolerance, and dry etch back properties, effectively protecting semiconductor wafers and maintaining film integrity during processing.
Implementation Method 1
cross-linking reaction does not sufficiently proceed at a curing temperature around 200° C.
Implementation Method 2
the insulating film formed on the rear surface of a wafer is required to be electrically insulative to prevent current leakage and migration of a conductive material
Implementation Method 3
dry etch back property in a photolithography step that is to open an electrode portion after forming a passivation film
Data Source
AI summary
There is provided a composition for forming a passivation film that satisfies electric insulation, heat-tolerance, solvent-tolerance, and a dry etch back property at the same time. A composition for forming a passivation film, including: a polymer containing a unit structure of Formula (i):T0-O Formula (i)(where T0 is a sulfonyl group, a fluoroalkylene group, a cycloalkylene group, or an arylene group having a substituent, or is a combination of an arylene group optionally having a substituent and a fluoroalkylene group or a cycloalkylene group), wherein the polymer has at least one of a group having a structure of Formula (2-A), a group having a structure of Formula (2-B), or a group having both of the structures, at an end, in a side chain, or in a main chain of the polymer:The polymer may contain a unit structure of Formula (1):L1-O-T1-O Formula (1)