Smart-cut of a thin foil of poruous Ni from a Si wafer
AssigneeUniversity of California, Los Angeles
InventorsXi Zhang, King-Ning Tu
Life of this patent
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Abstract
The present invention is a method of fabricating a self-peeling nickel foil from a silicon wafer. The method includes forming a template of silicon by electrochemically etching a portion of the Si wafer to create a porous Si portion with pores of a desired depth. Then electrolessly plating nickel into the template, wherein the porous silicon portion is converted into a porous nickel portion and continuing the electroless plating until the internal tensile stress at an interface of the porous nickel portion and the silicon wafer is great enough to self-peel the porous nickel portion from the silicon wafer creating a nickel foil.
Claims35
A method of fabricating a self-peeling nickel (Ni) foil from a silicon (Si) wafer, the method comprising:
- forming a template by electrochemically etching a porous Si portion in the Si wafer creating pores of a desired diameter and depth;
- electrolessly plating Ni into the template, wherein the porous Si portion is converted into a porous Ni portion;
- and
- continuing the electroless plating until the internal tensile stress at an interface of the porous Ni portion and the Si wafer is great enough to self-peel the porous Ni portion from the Si wafer creating the Ni foil.
A method of fabricating a self-peeling nickel (Ni) foil from a silicon (Si) wafer, the method comprising:
- applying a photo-resist to a surface of the Si wafer leaving an opening;
- forming a template by electrochemically etching a porous Si portion in the opening creating pores of a desired diameter and depth;
- pretreating the porous Si portion with APM (ammonium hydroxide, hydrogen peroxide, water mixture) at 70 to 80° C. for 15 minutes followed by DI water rinsing for 2 minutes, and then dilute HF (5%) dipping for 3 minutes at room temperature followed by DI water rinsing for 2 minutes;
- electrolessly plating Ni into the template, wherein the porous Si portion is converted into a porous Ni portion;
- and
- continuing the electroless plating until the internal tensile stress at an interface of the porous Ni portion and the Si wafer is great enough to self-peel the porous Ni portion from the Si wafer creating the Ni foil.
A nickel (Ni) foil prepared by a process comprising the steps of:
- (a) providing a silicon (Si) wafer with an exposed portion;
- (b) etching the exposed portion of the Si wafer for a first period of time with a chemical solution of HF, H2O and DMSO having adequate current density to form a porous Si portion on the Si wafer having macropores with an average diameter about 1 μm and a separation distance of each other of about 0.5 μm;
- (c) electrolessly plating the porous Si portion in a chemical bath containing NiSO4, NH4F, and (NH4)2SO4 for a second time period, wherein the porous Si portion is converted into a porous Ni foil;
- and
- (d) separating the Ni foil from the Si wafer.
Dependencies are inferred from the claim text.