Monocrystalline metal foil and manufacturing method therefor

1. A method for manufacturing a monocrystalline metal foil, the method comprising:

a) a step of fixing each end of a polycrystalline metal foil by electrodes, respectively; and

b) a step of heat treating the fixed polycrystalline metal foil to manufacture a monocrystalline metal foil,

wherein the step a) further comprises a step of keeping the polycrystalline metal foil straight with a minimized stress applied to the polycrystalline metal foil by moving one or more electrodes which are fixing each end of the polycrystalline metal foil, respectively, before the step b) of heat treating the fixed polycrystalline metal foil,

wherein the ends of the polycrystalline metal foil are opposite two edges of the polycrystalline metal foil, and a non-fixed portion, which is a region of the polycrystalline metal foil except for regions fixed by the electrodes is free of contact with solid materials, and

wherein heat treating is performed while maintaining the polycrystalline metal foil in a straightened state by moving the one or more electrodes by a movement distance no greater than to an increased length of the polycrystalline metal foil due to thermal expansion.

2. The method of claim 1 , wherein the heat treatment is performed by resistive heating.

3. The method of claim 1 , wherein the step b) is performed by including:

i) a primary heat treatment step of increasing a temperature of the polycrystalline metal foil by applying a current to the polycrystalline metal foil using the electrodes; and

ii) a secondary heat treatment step of performing annealing at a finally increased temperature for a predetermined time.

4. The method of claim 3 , wherein, in the primary heat treatment in the step i), the temperature is increased up to a temperature in the secondary heat treatment in the step ii).

5. The method of claim 4 , wherein the temperature in the secondary heat treatment satisfies the following Relational Expression 2,

0.3×T m ≤T<T m   [Relational Expression 2]

(in Relational Expression 2, T represents a temperature (° C.) in the secondary heat treatment, and T m represents a melting point temperature (° C.) of a metal of the polycrystalline metal foil).

6. The method of claim 1 , wherein a thickness of the polycrystalline metal foil is 5 to 200 μm.

7. The method of claim 1 , wherein a metal of the polycrystalline metal foil is copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), ruthenium (Ru), rhodium (Rh), palladium (Pd), platinum (Pt), silver (Ag), rhenium (Re), iridium (Jr), gold (Au), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), aluminum (Al), zinc (Zn), manganese (Mn), or tin (Sn).

8. The method of claim 1 , wherein the monocrystalline metal foil has the same crystal plane on both surfaces thereof.

9. The method of claim 1 , wherein the monocrystalline metal foil has a (110), (111), (001), (112), (123), or (0001) crystal plane based on a direction perpendicular to a plane.

10. The method of claim 1 , wherein the heat treatment is performed under a hydrogen gas atmosphere, an argon gas atmosphere, or a hydrogen-argon mixed gas atmosphere.