Specific Process Knowledge/Thin film deposition/DiamondCVD

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SEKI Diamond CVD

On the left is a tall instrument rack with various panels and control screens. It says "Seki technotron" on top. There are indicator lamps and an EMO button. On the right is the processing chamber which is relatively small, it's a cylindrical vacuum chamber with a small window facing the viewer. It's connected to gas lines and an exhaust system on top. There's a large panel covering the lower part of the instrument.
The SEKI diamond CVD in cleanroom B-1

The SEKI AX5250S is a Microwave Plasma Chemical Vapor Deposition (MPCVD) system for growth of diamond thin films. The system is fitted with gases for diamond growth, which are hydrogen, methane, and oxygen. Depending on the starting material both polycrystalline and single crystalline diamond can be grown. Diamond has a lattice constant of 3.567 Å, which is not easily matched to other materials, and therefore in general diamond growth must be seeded by diamond as nucleation sites. For single crystalline diamond this means that diamond layers in most cases must be grown on top of single crystal diamonds. For polycrystalline diamond, almost any material (which can handle 800 °C) will do. It just needs to be seeded with nano diamonds. The seeding can happen by immersion into solution, by polishing, or by spray coating with nano diamonds.

The user manual, APV, technical information, and contact information can be found in LabManager:

Diamond CVD in LabManager

Poly crystalline diamond growth

Two-inch wafer that has a speckled dark gray appearance with three small transparent partly overlapping squares in one area on top. The wafer is labeled as "polycrystalline diamond substrate" and the squares are labeled as "single crystal diamond"
Single- and polycrystalline diamond

For polycrystalline growth, the substrate must be seeded with diamonds. This is commonly done by sonicating the substrate in a solution of water with nano diamonds. After sonication the substrate is rinsed in water and blow-dried.

Structural formula diagrams of the growing diamond lattice showing how a hydrogen radical knocks off a hydrogen atom that terminates the diamond lattice, then a methane radical attaches to the activated site. The same thing happens at an adjacent site and finally one hydrogen radical after another knock off two hydrogen atoms on the recently-attached methane sites to create a new single carbon-carbon bond. The two new carbon atoms are also still bound to two hydrogen atoms each.
Single- and polycrystalline diamond

Equipment performance and process related parameters

Equipment SEKI AX5250S
Purpose Diamond growth
  • Single crystalline diamond
  • Poly crystalline diamond
Parameters

H2

1000 sccm

CH4

50 sccm

O2

20 sccm

Operating pressure

>200 Torr

Power

5000 W

Temperature

700-900 °C

Substrates Substrate size

up to 100 mm wafers, 50 mm prefered

Allowed materials

Ask


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