ECR

ECR plasma equipment and technology for micro and nano electronics and micromechanics

ECR plasma equipment and technology development for research and commercial applications:
    a) Epitaxial III-N thin film growth with improved MOCVD technique. Applications: material science, III-N heterostructures investigations, R&D, production of III-N HBLED, high power and low noise transistors etc.
    b) Micromechanical objects forming/etching. Applications: material science, nano scale objects forming/etching, deep etching with high aspect ratio, R&D, production of micro and nano mechanical sensors (membranes and nanoprobes), etc.

ECR plasma is microwave frequency plasma with external magnetic field applied to get the conditions of electron cyclotron resonance (ECR) – ω=eB/cm_e. ECR plasma has been known for about 20 years as a tool for thin film etching and deposition. The main problem with utilization such plasma that prevented its wide and commercial usage was stabilization plasma discharge. The project participants successfully solved this problem and proved ECR plasma prospectives.

ECR plasma has a number of significant advantages with respect to other types of plasma such as widely used inductively coupled plasma:
- High plasma density that means high density of active particles in a reactor chamber – high efficiency of chemical reactions;
- Low working pressure (0,1–20 mtorr) that means that the a particle free path is about a chamber size – all chemical reactions take place on a substrate surface, no clusters and by-products;
- Low particles energy (~20 eV) – less damages to a treated structure;
- ECR plasma source can be used as a source of atomic nitrogen – significantly lower growth temperature, no aggressive ammonia for nitrogen-containing structures such as III-N or Si₃N₄;
- Anisotropic etching is available by applying high frequency biasing.

The first laboratory scale ECR plasma equipment was developed and manufactured in the Institute of Microelectronics Technology of the Russian Academy of Sciences. The equipment was used for fundamental investigation of ECR plasma and related processes as well as ECR plasma application for thin film etching and deposition.

The first generation of laboratory scale ECR equipment

Jointly with EZAN and EpiLab, LLC. the ECR machines were elaborated, upgraded and improved. Two types of pilot ECR machines for thin film etching and deposition were designed and manufactured.

Pilot ECR machine for Si3N4 film deposition

Pilot ECR machine for III-N epitaxial film growth

Fully automated pilot ECR machine for precision thin film etching

The new pilot ECR machines allowed to improve the technology significantly and define fields of ECR plasma application:

- Delicate precision etching of semiconductor structures;
- Anisotropic etching of layered thin film structures;
- Forming micromechanical objects with characteristic size less that 100 nm;
- High power and low noise transistors Si₃N₄ passivation;
- AlGaN/GaN (III-N) epitaxial thin film growth with improved MOCVD technique – the growth temperature is ~700º C with respect to ~1200º C for common MOCVD technique and no ammonia is used;
- Forming of micromechanical sensors directly on multiplexer chips.



ECR equipment parameters:

- Microwave frequency power: 700-5000 W
- High frequency bias: -20 to -200 V
- Substrate: 2-4”
- Manual substrate load/unload
- Initial pressure: 10^-7 Torr
- Working pressure: 0,1 – 10 mTorr
- Microwave frequency generator: continuous mode / pulse mode (modulation up to 200 kHz) with vector tuner
- Automated deposition/etching process
- Substrate holder temperature: up to 800o C


The brand new field of ECR plasma application being developed by the project participants is ECR PECVD deposition of nanocrystalline Si films for solar cells elements as well as diamond films deposition and bulk diamond crystals growing. ECR PECVD Si film deposition opens new prospective ways for the modern solar power industry development.

Etching: T-shaped gated for low-noise and high power transistors. The T-gate width is 100 nm.

Etching: “Hanging pixel” of uncooled bolometric matrix and a fragment of “gecko foot” adhesive coating

Deposition: Output power and coefficient of efficiency increase after Si3N4 passivation of AlGaN/GaN HEMT

The ECR plasma usage for III-N epitaxy – unique and prospective alternative to the commonly used MBE and MOCVD techniques.

Electron diffraction pattern of GaN film grown at 500º (right picture) and 700º C (left picture) with atomic nitrogen generated by ECR plasma. Left picture – epitaxial growth regime is achieved. No ammonia is used.




Basing on the achieved result the current aims are the following: