Cathode PECVD for High-rate SiO2 and SiNx Deposition

SAMCO Inc. > Featured Solutions > Cathode PECVD

Plasma Enhanced Chemical Vapor Deposition (PECVD)  is one of the most fundamental processes in microelectronics fabrication. While most of the PECVD equipment manufacturers provide anode-driven PECVD processes, SAMCO also offers a unique Cathode PECVD system which provides high-rate deposition with good step coverage.

Cathode PECVD

What is Anode PECVD?

In the Anode PECVD configuration, the RF power is applied to the upper electrode (Anode) and the substrate electrode (Cathode) is grounded. The PECVD uses this electrical energy to generate a plasma in which the energy is transferred into a gas mixture.  This transforms the gas mixture into radicals, ions, neutral atoms and molecules.
The result is that fewer ions are attracted to the substrate, and it is useful for devices which are sensitive to Ion Damage.

Anode PECVD

Schematic image of anode PECVD chamber

SAMCO offers anode PECVD processes for R&D and production of various devices.

SAMCO’s process capabilities of anode PECVD are as follows.

1. Superior deposition uniformity

Anode-CVD-Uniformity

2. Excellent stress control

Anode-CVD-RF-Power-vs-Film-Stress

RF Power vs. Film Stress

3. Good step coverage

Nitride step coverage by anode pecvd process

Step coverage of SiNx by anode PECVD

One of the disadvantages of anode PECVD processes is a low deposition rate (typically around 50 nm/min) due to lower ion energy.

What is Cathode PECVD?

An RF-driven cathode makes maximum use of a self bias voltage by placing the sample on the cathode electrode. Ions are accelerated by the negative electric field of the cathode.

Compared to traditional anode PECVD technologies, SAMCO’s proprietary cathode coupled PECVD technologies show various advantages.

Cathode PECVD chamber

Schematic image of Cathode PECVD chamber

High-speed and Thick Film Deposition

0nm/min, Oxide Deposition
0µm Thick Oxide

High-speed deposition processes are achieved by utilizing cathode-driven high-energy ions. Compared to traditional anode PECVD processes (typically around 50 nm/min), cathode PECVD processes show higher oxide deposition rate of 167 nm/min.

High deposition rate of cathode PECVD

Deposition Time vs. Oxide Thickness

The cathode coupled high-speed PECVD processes show significant advantages over anode PECVD in the case of thick film deposition. Oxide overclad layer is deposited faster without cracking. The layer also has superior step coverage. These processes are applicable to lightwave circuits fabrication and gap-filling of metal lines.

Overclad formation without cracking

25 µm Thick Over-clad Formation

Overclad formation without cracking

7.6 µm Thick Gap-filling

Safe Deposition Without Using SiH4

Silane (SiH4) is widely used for PECVD processes to obtain high quality films. One of the drawbacks of a SiH4-based PECVD process is the safety issue. SiH4 is a flammable gas and easily ignite on contact with air. Also, the gas has toxicity to the human body. Therefore, device manufacturers need to take care of the gas use in production lines in the aspect of environment, health and safety (EHS).

For more than 20 years, SAMCO has been working on taking advantage of safer PECVD processes using liquid source Tetraethyl Orthosilicate (TEOS). TEOS is safer and easier to handle compared to SiH4, and it can create as good a film as SiH4.
The synergy of TEOS and cathode coupling enables a high quality Silicon Oxide (SiO2) films with excellent step coverage on high aspect ratio which is particularly suited to via holes in a TSV process.

Excellent Step Coverage of Cathode PECVD using TEOS

Oxide Step Coverage of TSV

Excellent Step Coverage of Cathode PECVD using TEOS

Low Temperature Deposition

Traditionally, PECVD processes have required  high temperature over 250°C to meet film quality demands. However,  a variety of materials such as polymers and adhesives used for MEMS devices fabrication do not have enough heat durability. Therefore, our customers using these materials required low-temperature deposition processes.

SAMCO offers a unique low-temperature deposition process utilizing the cathode PECVD technologies. The self-bias collects ions efficiently, and the high electric field on the cathode does not require high temperature for film deposition. The deposition process at low temperature of 80°C shows higher deposition rate than a typical Anode PECVD process at 300°C.

Low temperature deposition

Oxide Deposition Rate at 80°C vs. at 300°C

Controllable Film Properties

SAMCO’s cathode PECVD processes show highly controllable film properties.
These are some examples. For more specific data, please feel free to contact us.

1. Wet Etch Rate

Wet Etch Rate of SiN by Cathode PECVD

Bias RF Power vs. Wet Etch Rate
Wet Etch Condition: 1% HF
Solution Temperature of 25°C

2. Film Hardness

Hardness Control of SiN by Cathode PECVD

Self Bias Voltage vs. Film Hardness

3. Film Stress

Stress Control of SiN by Cathode PECVD

Bias RF Power vs. Film Stress

The Value of SAMCO’s PECVD Processes

Advantage of SAMCO process solutions

Throughput enhancement with high-rate deposition

SAMCO’s cahode PECVD processes enable high-volume manufacturing with high deposition rates.

Advantage of SAMCO process solutions

Satisfying various demands on film properties

SAMCO’s controllable PECVD processes are suitable for R&D to achieve process goals.

Advantage of SAMCO process solutions

A wide range of systems

SAMCO offers anode and cathode PECVD solutions for R&D and production. SAMCO covers multiple wafer sizes from batch processing of small wafers to 450 mm.

 SAMCO Cathode PECVD Systems

SAMCO offers Cathode PECVD systems for both R&D and production.

 PD-270STP

SAMCO PD-270STP

– for R&D
– Open-load System
– Processing up to ø8”wafers

 PD-270STL

SAMCO PD-270STLC

– for R&D and pilot production
– Loadlock System
– Batch processing of small wafers or processing up to ø8”wafers

 PD-330STC

SAMCO PD-330STC

– for production
– Cassette-to-cassette System
– Batch processing of small wafers or processing up to ø12”wafers

  • SAMCO Cathode PECVD

Reference

More detail on SAMCO’s Cathode PECVD technologies can be found on “Chapter 3 TSV Processes” of the book below.

Three-Dimensional Integration of Semiconductors Processing, Materials, and Applications
Editors: Kazuo Kondo, Morihiro Kada, Kenji Takahashi
ISBN: 978-3-319-18674-0 (Print) 978-3-319-18675-7 (Online)

Contact SAMCO for more product information
Any questions? Contact us for more detail.
Contact SAMCO for more product information
Any questions? Contact us for more detail.
Contact SAMCO for more product information
Any questions? Contact us for more detail.
Contact SAMCO for more product information
Contact us for more detail.
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