IGZO Sputtering Target Spinel Phase Control
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Solution Overview
Problem
The production of a high-density, sputtering target for DC sputtering using In-Ga-Zn-O (IGZO) is hindered by the formation of spinel phases, which leads to nodules and abnormal discharge, affecting the quality and conductivity of the sputtered film.
Innovation Solution
A sintered oxide compact target with a composition ratio of In x Ga y Zn z O a, where 0.2 ≦ x / (x + y) ≦ 0.8 and 0.1 ≦ z / (x + y + z) ≦ 0.5, and a reduced number of ZnGa2O4 spinel phases with an average grain size of 3µm or larger in a 90µm × 90µm area, achieving a bulk resistance value of 5.0 × 10^-2 Ω•cm or less, is developed. The target is produced by adjusting the composition ratio and sintering temperature of indium oxide, gallium oxide, and zinc oxide powders, ensuring sufficient pulverization and mixing to inhibit spinel phase formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If In-Ga-Zn-O oxide target is manufactured by mixing oxide powders and sintering, then the target can be produced, but spinel phases form causing nodules and abnormal discharge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of In, Ga, and Zn oxides within specific ranges, and by optimizing sintering temperature and atmosphere parameters. These parameter adjustments prevent the formation of spinel phases while maintaining target density and electrical conductivity, thereby eliminating nodules and abnormal discharge during sputtering
Solution Approach 2:
The patent creates a composite oxide material with a specific multi-component composition (In-Ga-Zn-O system) where the synergistic interaction between different metal oxides prevents spinel phase formation. The composite structure with controlled grain boundaries and phase distribution ensures both manufacturability and sputtering reliability
2Productivity
If DC sputtering is performed with conventional IGZO target, then high deposition rate is achieved, but abnormal discharge occurs due to nodules
Solution Approach 1:
The patent applies preliminary action by pre-preparing a high-quality target with optimized composition and microstructure before sputtering. The target is pre-sintered under controlled conditions to eliminate spinel phases and ensure uniform density, so that during DC sputtering, abnormal discharge and nodules are prevented from occurring, maintaining both high deposition rate and stable discharge
3Manufacturing precision
If sintering temperature is increased to improve target density, then bulk resistance decreases, but spinel phase formation is promoted
Solution Approach 1:
The patent resolves this contradiction by changing multiple parameters simultaneously: optimizing the composition ratios of metal oxides, controlling sintering temperature within a specific range, and adjusting sintering atmosphere. This multi-parameter optimization achieves high target density and low bulk resistance while suppressing spinel phase formation that would occur at higher temperatures
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 reduces nodule generation and abnormal discharge, enabling stable and high-density DC sputtering with improved film quality and conductivity.
Implementation Method 1
The direct current (DC) sputtering method requires a target, but an In-Ga-Zn-O (IGZO) series oxide target is not easily manufactured.
Data Source
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AI summary
Provided is a sintered oxide compact target for sputtering comprising indium (In), gallium (Ga), zinc (Zn), oxygen (O) and unavoidable impurities, wherein the composition ratio of the respective elements satisfies the Formula of In x Ga y Zn z O a wherein 0.2 ‰¦ x / (x + y) ‰¦0.8, 0.1 ‰¦z / (x + y + z) ‰¦0.5, a = (3/2) x + (3/2) y + z}, and the number of ZnGa 2 O 4 spinel phases having an average grain size of 3µm or larger existing in a 90µm × 90µm area range of the sintered oxide compact target is 10 or less. With this sintered oxide compact target for sputtering comprising In, Ga, Zn, O and unavoidable impurities, the structure of the sintered compact target is improved, the formation of a phase to become the source of nodules is minimized, and the bulk resistance value is reduced. Whereby provided is a high density IGZO target capable of inhibiting abnormal discharge and which can be used in DC sputtering.