Indium Tin Oxide Sputtering Target Composition for Low Resistivity
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Solution Overview
Problem
Existing methods for producing transparent conductive films face challenges in achieving an amorphous state without heating the substrate or adding water during sputtering, while also requiring low-temperature annealing and low resistivity after crystallization, which is not efficiently addressed by prior arts.
Innovation Solution
An oxide sintered compact with specific compositions, including indium oxide, tin, and additional elements like germanium, nickel, manganese, and aluminum, is used as a sputtering target to produce an amorphous film that can be easily crystallized at low temperatures, achieving low resistivity and preventing etching residue issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If water is added during sputtering to amorphize the film, then the film remains amorphous and etching rate is high, but particles are generated on the film and water concentration control is difficult
Solution Approach 1:
The patent removes water from the sputtering process entirely, extracting the harmful factor (particle generation caused by water addition) while achieving the desired amorphous film state through alternative means - specifically by controlling the target composition (In-Sn-Ge system with specific ratios) and sputtering conditions without any water vapor introduction
Solution Approach 2:
The patent changes the compositional parameters of the sputtering target (specific ratios of In, Sn, and Ge elements) and sputtering conditions (gas pressure, power density) to achieve amorphous film formation without water addition. The Ge content is controlled at 0.1-2 atom% to suppress crystallization while avoiding particle generation
2Stability of the object's composition
If water concentration is increased to reliably obtain amorphous film, then crystallization is prevented, but crystallization temperature becomes extremely high and resistivity increases
Solution Approach 1:
The patent changes the compositional parameters of the target material (In-Sn-Ge system with specific atomic ratios) to fundamentally alter the film's crystallization behavior. By controlling Ge content at 0.1-2 atom% and Sn content at 2-15 atom%, the film achieves amorphous stability at lower temperatures and crystallizes at moderate temperatures (200-400°C) with low resistivity, eliminating the need for high water concentration
3Stability of the object's composition
If substrate is heated during sputtering to control crystallization, then film crystallinity can be controlled, but productivity decreases and etching rate reduces
Solution Approach 1:
The patent extracts the heating step from the sputtering process, achieving amorphous film formation and subsequent crystallization control without substrate heating. The film is deposited in amorphous state at room temperature and then crystallized through post-deposition annealing, maintaining high etching rates during the amorphous stage
Solution Approach 2:
The patent performs amorphous film deposition first, then applies post-deposition annealing to induce crystallization. This preliminary formation of amorphous structure followed by controlled crystallization allows high etching rates during etching (when amorphous) and low resistivity after annealing (when crystalline)
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 approach results in an amorphous film that can be crystallized at 160-250°C, maintaining low resistivity and avoiding etching residue problems, with resistivity as low as 4.5×10−4Ω cm, enhancing productivity and economic viability.
Implementation Method 1
The deposition method of the ITO film in today's industrial production process is mostly based on the so-called sputter deposition method of performing sputtering using an ITO sintered compact as the target
Implementation Method 2
thermal annealing is subsequently performed to crystallize the ITO film
Implementation Method 3
the ITO film immediately after the sputtering is amorphous... thermal annealing is subsequently performed to crystallize the ITO film
Data Source
AI summary
The present invention provides a sputtering target suitable for producing an amorphous transparent conductive film which can be formed without heating a substrate and without feeding water during the sputtering; which is easily crystallized by low-temperature annealing; and which has low resistivity after the crystallization. An oxide sintered compact containing an indium oxide as a main component, while containing tin as a first additive element, and one or more elements selected from germanium, nickel, manganese, and aluminum as a second additive element, with the content of tin which is the first additive element being 2-15 atom % relative to the total content of indium and tin, and the total content of the second additive element being 0.1-2 atom % relative to the total content of indium, tin and the second additive element.