Sputtering Target Material for Suppressing Abnormal Discharge
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Solution Overview
Problem
Existing sputtering target materials for forming miniaturized and thinned copper films in semiconductor devices and flat panel displays face challenges in suppressing abnormal discharge (arcing) during long-term use, leading to uneven film thickness and particle generation due to crystal grain coarsening and preferred orientation concentration.
Innovation Solution
A sputtering target material containing specific impurities like Ag, As, Pb, Sb, Bi, Cd, Sn, Ni, and Fe in controlled amounts, combined with high-purity copper, to maintain a small average crystal grain size and random crystal orientation, suppressing abnormal discharge through electron backscatter diffraction criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pure copper sputtering target is used, then the specific resistivity of the wiring film is reduced, but abnormal discharge occurs due to foreign matter and crystal grain coarsening during long-term use
Solution Approach 1:
The patent changes the chemical composition parameters by adding specific impurity elements (Ag, As, Pb, Sb, Bi, Cd, Sn, Ni, Fe) in controlled amounts (5-50 massppm total) to the copper target. This compositional modification prevents crystal grain coarsening and suppresses abnormal discharge during long-term sputter deposition, resolving the contradiction between maintaining high copper purity for low resistivity and preventing harmful arcing effects
Solution Approach 2:
The patent creates a composite material system by combining copper with multiple trace elements having different atomic sizes and properties. This composite structure suppresses crystal grain growth and stabilizes the target material during prolonged use, eliminating abnormal discharge while maintaining the electrical conductivity benefits of copper
2Object-affected harmful factors
If the crystal grain size is reduced, then abnormal discharge is suppressed, but the manufacturing complexity increases due to multiple impurity control requirements
Solution Approach 1:
The patent applies local quality by introducing specific impurity elements at trace levels (5-50 massppm) that locally modify the crystal grain boundaries and dislocation structures. These localized compositional adjustments suppress crystal grain coarsening and abnormal discharge without requiring extensive global compositional changes, thereby limiting manufacturing complexity
3Reliability
If high-purity copper is used, then the electrical conductivity is improved, but the crystal grain coarsens during long-term use leading to deposition instability
Solution Approach 1:
The patent modifies the compositional parameters by adding trace amounts of specific elements that act as grain boundary pinning agents. These elements change the thermodynamic and kinetic parameters of crystal grain growth, preventing coarsening during long-term sputter deposition and maintaining both electrical conductivity and structural stability
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 stabilizes sputter deposition by reducing abnormal discharge occurrences, ensuring efficient and stable formation of miniaturized copper films even in long-term use, while maintaining suitable specific resistivity for wiring applications.
Implementation Method 1
The above described wiring film is usually deposited in a vacuum atmosphere using a sputtering target
Data Source
AI summary
A sputtering target material contains one kind or two or more kinds selected from the group consisting of Ag, As, Pb, Sb, Bi, Cd, Sn, Ni, and Fe in a range of 5 massppm or more and 50 massppm or less, in terms of a total content; and a balance consisting of Cu and an inevitable impurity. In the sputtering target material, in a case in which an average crystal grain size calculated as an area average without twins is denoted by X1 (μm), and a maximum intensity of pole figure is denoted by X2, upon an observation with an electron backscatter diffraction method, Expression (1): 2500>19×X1+290×X2 is satisfied, a kernel average misorientation (KAM) of a crystal orientation measured by an electron backscatter diffraction method is 2.0° or less, and a relative density is 95% or more.