Polycrystalline Conductive Films on Hexagonal Substrates
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Solution Overview
Problem
Conductive films on semiconductor substrates often exhibit epitaxial growth, resulting in large grains and a peculiar appearance due to symmetry equivalence with the substrate's atomic arrangement, which is undesirable.
Innovation Solution
A semiconductor device with a substrate having a hexagonal crystal structure and conductive films where the first conductive film lacks symmetry equivalent to the substrate's atomic arrangement, and the second conductive film is polycrystalline with a grain size of no more than 15 μm, formed using methods like plasma irradiation or dry etching to prevent epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conductive film is formed on a substrate with matching crystal symmetry, then epitaxial growth occurs improving film crystallinity, but large grains form creating a peculiar appearance
Solution Approach 1:
The patent applies asymmetry by selecting a conductive film material whose crystal structure does not have symmetry equivalent to the substrate's atomic arrangement. This mismatched symmetry prevents epitaxial growth, thereby avoiding large grain formation and the associated peculiar appearance while still achieving a flat surface.
2Ease of manufacture
If conventional deposition methods are used, then conductive films can be formed, but epitaxial growth creates large grains and peculiar appearance
Solution Approach 1:
The patent changes the crystallographic parameter by selecting a conductive film material with a crystal structure that lacks symmetry equivalence to the substrate. This parameter change fundamentally alters the growth behavior from epitaxial to non-epitaxial, preventing large grain formation while maintaining surface flatness through controlled deposition.
3Manufacturing precision
If epitaxial growth is allowed, then crystal structure alignment improves, but grain size increases beyond acceptable limits
Solution Approach 1:
By choosing a conductive film material whose crystal structure does not match the substrate's symmetry, the patent prevents epitaxial growth and the associated crystal alignment. This asymmetry selection effectively limits grain size to 15 μm or less, avoiding the peculiar appearance while still achieving acceptable manufacturing precision through alternative deposition control.
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 prevents epitaxial growth, resulting in a flat surface and minimizing the occurrence of a peculiar appearance, ensuring the conductive films remain polycrystalline with controlled grain size, thus enhancing the semiconductor device's appearance and performance.
Implementation Method 1
applying plasma irradiation, ion milling, or dry etching to a (0001) surface of a substrate
Implementation Method 2
applying plasma irradiation, ion milling, or dry etching to a (0001) surface of a substrate
Implementation Method 3
applying plasma irradiation, ion milling, or dry etching to a (0001) surface of a substrate
Implementation Method 4
The over-the-amorphous conductive film is polycrystalline, has a grain size of no more than 15 μm
Data Source
AI summary
A semiconductor device includes a substrate having a hexagonal crystalline structure and a (0001) surface, and conductive films on the surface of the substrate. The conductive films include a first conductive film and a second conductive film located above the first conductive film with respect to the surface, wherein the first conductive film has a crystalline structure which does not have a plane that has a symmetry equivalent to the symmetry of atomic arrangement in the surface of the substrate, the second conductive film has a crystalline structure having at least one plane that has a symmetry equivalent to the symmetry of atomic arrangement in the surface of the substrate, and the second conductive film is polycrystalline and has a grain size no larger than 15 μm.