Method for manufacturing a molybdenum sputtering target for back electrode of CIGS solar cell

Patent metadata

Field	Value
Publication number	US-9506141-B2
Application number	US-201214002666-A
Country	US
Kind code	B2
Filing date	Mar 7, 2012
Priority date	Mar 8, 2011
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A method for manufacturing a molybdenum sputtering target for a back electrode of a CIGS solar cell is provided to minimize thermal activating reaction by employing an electric discharge plasma sintering process. The method for manufacturing a molybdenum sputtering target for a back electrode of a CIGS solar cell comprises the steps of: charging molybdenum powder in a mold of graphite material, mounting the mold in a chamber of an electric discharge sintering apparatus, making a vacuum in the chamber, forming the molybdenum powder to the final target temperature while maintaining constant pressure on the molybdenum powder, heating the molybdenum powder in a predetermined heating pattern when reaching the final target temperature, maintaining the final target temperature for 1 to 10 minutes, and cooling the inside of the chamber while maintaining a constant pressure.

First claim

What is claimed is:

1. A method for manufacturing a molybdenum sputtering target of a CIGS solar cell, the method comprising: (a) filling molybdenum powder in a mold made of graphite; (b) mounting the mold filled with the molybdenum powder into a chamber of a discharge plasma sintering device; (c) evacuating the inside of the chamber; (d) heating the mold until a final target temperature is reached while elevating the temperature according to a preset temperature elevating pattern in a state in which the molybdenum powder in the mold is maintained at a constant pressure; (e) maintaining the final target temperature for 1 to 10 minutes; and (f) cooling the inside of the chamber while maintaining a predetermined pressure,
wherein in the step (d), the pressure of the inside of the mold is maintained at 50 to 70 MPa, and the step (d) comprises: (d-1) firstly elevating the temperature of the molybdenum powder in the mold to 600.degree. C., which is a first target temperature, at a rate of 30.degree. C./min to 100.degree. C./min; (d-2) maintaining the first target temperature for 1 to 3 minutes; (d-3) secondly elevating the temperature of the molybdenum powder in the mold to 700.degree. C., which is a second target temperature, at a rate of 10.degree. C./min to 50.degree. C./min; (d-4) maintaining the second target temperature for 1 to 3 minutes; (d-5) thirdly elevating the temperature of the molybdenum powder in the mold to 800.degree. C., which is a third target temperature, at a rate of 10.degree. C./min to 50.degree. C./min; (d-6) maintaining the third target temperature for 1 to 3 minutes; (d-7) fourthly elevating the temperature of the molybdenum powder in the mold to 900.degree. C., which is a fourth target temperature, at a rate of 10.degree. C./min to 50.degree. C./min; (d-8) maintaining the fourth target temperature for 1 to 3 minutes; (d-9) fifthly elevating the temperature of the molybdenum powder in the mold to 1000.degree. C., which is a fifth target temperature, at a rate of 10.degree. C./min to 50.degree. C./min; (d-10) maintaining the fifth target temperature for 1 to 3 minutes; (d-11) sixthly elevating the temperature of the molybdenum powder in the mold to 1100.degree. C., which is a sixth target temperature, at a rate of 10.degree. C./min to 50.degree. C./min; (d-12) maintaining the sixth target temperature for 1 to 3 minutes; and (d-13) seventhly elevating the temperature of the molybdenum powder in the mold to 1200.degree. C., which is the final target temperature, at a rate of 10.degree. C./min to 50.degree. C./min.

2. The method of claim 1 , wherein the step (a) comprises filling the molybdenum powder into the mold and performing a preliminary pressing process using a molding press with a pressure of 1400 to 1600 kgf to be allowed to stand undisturbed for 1 to 10 minutes.

3. The method of claim 2 , wherein a plurality of upper spacers made of graphite are formed between an upper electrode in the chamber to apply an electric field to the mold and an upper punch entering the mold from a top, the plurality of upper spacers having outer diameters gradually decreasing toward the upper punch, and a plurality of lower spacers made of graphite are formed between a lower electrode in the chamber and a lower punch entering the mold from a bottom, the plurality of lower spacers having outer diameters gradually decreasing toward the lower punch, the upper spacer is provided with a first upper spacer, a second upper spacer and a third upper spacer, which are arranged from the upper electrode to the upper punch in a circular shape, the lower spacer is provided with a first lower spacer, a second lower spacer and a third lower spacer, which are arranged from the lower electrode to the mold in a circular shape, the first upper spacer and the first lower spacer have a diameter of 350 mm and a thickness of 30 mm, the second upper spacer and the second lower spacer have a diameter of 300 mm and a thickness of 60 mm, and the third upper spacer and the third lower spacer have a diameter of 200 to 250 mm and a thickness of 30 to 60 mm.

4. The method of claim 3 , wherein the step (c) comprises evacuating the inside of the chamber to a pressure of 1.times.10.sup.0 Pa to 1.times.10.sup.-3 Pa to prevent the molybdenum powder from being oxidized or to suppress formation of a secondary phase due to gas or impurity, and the step (f) comprises cooling while allowing the inside of the mold to stand undisturbed at a pressure of 50 to 70 MPa.

Assignees

• Oh Ik Hyun
• Park Hyun Kuk
• Lee Seung Min
• Yang Jun Mo
• Korea Ind Tech Inst

Inventors

• Oh Ik Hyun
• Park Hyun Kuk
• Lee Seung Min
• Yang Jun Mo

Classifications

• B22F2003/1051

  by electric discharge · CPC title

• Y02P70/521

  Cross-Sectional Technologies · mapped topic

• B22F3/1017

  Multiple heating or additional steps (B22F3/101 takes precedence) · CPC title

• B22F2201/20

  Use of vacuum · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title