Molten target sputtering (MTS) deposition for enhanced kinetic energy and flux of ionized atoms

Patent metadata

Field	Value
Publication number	US-10947639-B2
Application number	US-201715463778-A
Country	US
Kind code	B2
Filing date	Mar 20, 2017
Priority date	Mar 18, 2016
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

Various embodiments provide Molten Target Sputtering (MTS) methods and devices. The various embodiments may provide increases in the kinetic energy, increases in the energy latency, and/or increases in the flux density of molecules for better crystal formation at low temperature operation. The various embodiment MTS methods and devices may enable the growth of a single crystal Si1-xGex film on a substrate heated to less than about 500° C. The various embodiment MTS methods and devices may provide increases in the kinetic energy, increases in the energy latency, and/or increases in the flux density of molecules without requiring the addition of extra systems.

First claim

What is claimed is:

1. A sputtering gun, comprising:
a heat sink having magnets encased at least partially by a surface of the heat sink, wherein the heat sink is configured to form a ring groove on the surface of the heat sink encasing the magnets;
a retainer ring configured to support the heat sink and a target material for sputtering on a substrate such that:
the target material contacts the surface of the heatsink thereby forming an empty space between the ring groove on the surface of the heat sink and the target material; and
both the magnets and the ring groove on the surface of the heat sink are under the target material;

wherein the ring groove abuts the target material such that the empty space is in direct communication with the target material, the empty space being configured to be unfilled;
wherein the ring groove is configured to reduce heat flow and retain thermal energy to at least partially melt a surface of the target material opposite a surface of the target material contacted by the surface of the heat sink; and
wherein the sputtering gun is configured such that, during operation of the sputtering gun, atoms of the target material from the at least partially melted surface are ejected toward the substrate for condensative dangling of the target material on the substrate.

2. The sputtering gun of claim 1 , wherein:
the magnets comprise a ring of magnets and a center magnet positioned within the ring of magnets;
the ring groove is formed in the surface of the heat sink between the ring of magnets and the center magnet.

3. The sputtering gun of claim 2 , wherein the heat sink is a tubular water cooled copper heat sink.

4. The sputtering gun of claim 1 , wherein a depth and a width of the ring groove are both a same value from about 1 mm to about 2 mm.

5. A Molten Target Sputtering (MTS) system, comprising:
a vacuum chamber;
a substrate support configured to support a substrate within the vacuum chamber; and
a sputtering gun, disposed within the vacuum chamber and oriented in relation to the substrate support such that, during operation of the sputtering gun, atoms of a target material are ejected toward the substrate for condensative dangling of the target material on the substrate, comprising:
a heat sink having magnets encased at least partially by a surface of the heat sink, wherein the heat sink is configured to form a ring groove on the surface of the heat sink encasing the magnets; and
a retainer ring configured to form a trapped magnetic field in operation and to support the heat sink and the target material for sputtering on the substrate such that:
the target material contacts the surface of the heatsink thereby forming an empty space between the ring groove on the surface of the heat sink and the target material; and
both the magnets and the ring groove on the surface of the heat sink are under the target material;

wherein the MTS system is configured such that during operation of the MTS system:
a portion of a magnetic field generated by the magnets is trapped within the ring groove creating a trapped magnetic field;
a direct current (DC) or radio frequency (RF) discharge plasma volume is deflected by the trapped magnetic field to position the plasma over the surface of the target material above the ring groove of the heat sink, whereby heating the surface of the target material is accelerated to cause the surface of the target material to change to a liquid phase; and
the atoms of the target material are readily sputtered onto the substrate, the trapped magnetic field providing an additive force to push out the plain atoms and ionized atoms of the target material;

wherein the ring groove abuts the target material such that the empty space is in direct communication with the target material, the empty space being configured to be unfilled; and
wherein the ring groove is configured to reduce heat flow and retain thermal energy to at least partially melt a surface of the target material.

6. The MTS system of claim 5 , wherein:
during operation of the MTS system the substrate's temperature is at or below about 500° C.; and
the substrate is composed of sapphire, the sputtering of the atoms of the target material onto the substrate being configured to grow a single crystal SiGe film on the substrate.

7. The MTS system of claim 5 , wherein the sputtering gun is configured such that:
the magnets comprise a ring of magnets and a center magnet positioned within the ring of magnets; and
the ring groove is formed in the surface of the heat sink between the ring of magnets and the center magnet.

8. The MTS system of claim 7 , wherein the heat sink is a tubular water cooled copper heat sink.

9. The MTS system of claim 7 , wherein a depth and a width of the ring groove are both a same value from about 1 mm to about 2 mm.

10. The MTS system of claim 9 , wherein the plasma volume consists of one or more of argon and nitrogen.

11. The MTS system of claim 10 , wherein the surface of the target material is changed to the liquid phase with the retained thermal energy by the ring groove only as a thermally insulating gap and without addition of an electron beam, an ion beam, or a high power pulse mode.

12. The MTS system of claim 11 , wherein the plain atoms and ionized atoms removed from the target material are sputtered onto the substrate with a flux density at or above about 2 nanometers per second and a kinetic energy at or above about 5 electronvolts.

13. A Molten Target Sputtering (MTS) method, comprising:
heating a substrate within a vacuum chamber to a designated temperature;
providing a direct current (DC) or radio frequency (RF) discharge plasma volume to position and contact a surface of a target material supported by a retainer ring of a sputtering gun thereby heating the surface of the target material causing the surface of the target material to change to a liquid phase, wherein:
the sputtering gun comprises a heat sink having magnets encased at least partially by a surface of the heat sink and the heat sink is configured to form a ring groove on the surface of the heat sink encasing the magnets; and
the target material is supported by the retainer ring such that:
the target material contacts the surface of the heatsink thereby forming an empty space between the ring groove on the surface of the heat sink and the target material; and
both the magnets and the ring groove on the surface of the heat sink are under the target material;

configuring the ring groove to abut the target material such that the empty space is in direct communication with the target material,
keeping the empty space as unfilled;
preventing conductive dissipation of heat from the target material via the ring groove, thereby retaining thermal energy to increase a temperature of the target material;
trapping a portion of a magnetic field generated by the magnets within the ring groove to create a trapped free space magnetic field, wherein the trapped free space magnetic field keeps the DC or RF plasma volume positioned on the surface of target material directly opposite and above the ring groove; and
sputtering atoms of the target material onto the substrate by ejecting the atoms of the target material toward the substrate to thereby cause condensative dangling of the target material on the substrate, the trapped magnetic field providing an additive force to push out the sputtered atoms from the target material.

14. The method of claim 13 , wherein:
the designated temperature is at or below about 500° C.; and
the substrate is composed of sapphire, the sputtering of the atoms of the target ma

Assignees

• Nasa

Inventors

• Kim Hyun Jung
• Choi Sang H

Classifications

• H10P14/3458

  Monocrystalline · CPC title

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H10P14/2921

  being crystalline insulating materials · CPC title

• H10P14/22

  using physical deposition, e.g. vacuum deposition or sputtering · CPC title

• H01J37/32082

  Radio frequency generated discharge (H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence) · CPC title