SPE ESTO began to develop plasma etching equipment for mass production

Research and Production Enterprise Electronic Special Process Equipment (SPE ESTO JSC) has moved to the final stage of the project for the production of plasma etching equipment for mass production of VLSIs of 65-28 nanometre level. The implementation of the project began in 2016 with the financial support of the Ministry of Industry and Trade of the Russian Federation.

The main technological module of the device is a unique process chamber (PC) for plasma chemical etching of dielectrics, proven and accepted in modern 300 mm industrial production. On this basis, the company "NPP "ESTO" has developed a scaled to 200 mm etcher (oxide, nitride, polymers, low-k, p-Si, TSV, etc.) with overlapping range of all process parameters, unattainable for any other industrial system on the market.

The original plasma source is the world's only flat, narrow-gap (30-40 mm) process inductively coupled plasma (ICP) generator known as Groovy ICP. It is known that the conventional inductive discharge (ICP = Inductively Coupled Plasma), implemented in a large volume, is characterized by a wide range of pressure and power. And the narrow gas gap, i.e. minimum volume typical for capacitively coupled plasma (CCP = Capacitively Coupled Plasma), guarantees the best kinetic control of the gas composition due to short gas residence time in the plasma.

"The unique Groovy ICP source combines the advantages of both basic plasma sources (ICP-CCP) in such a way that all their advantages are combined and disadvantages are leveled. A PC with such a source makes it possible to implement all plasma chemical processes in a single basic PC, changing only the internal equipment. The single reactor configuration enables us to create a complete line of plasma-chemical reactors and achieve high economic efficiency in machine production and technology versatility," explained the company.

Technical features

Wide range of process parameters is ensured not only in the discharge volume but also on the surface of the wafer. The module is equipped with a state-of-the-art electrostatic clamping table (ESC) with a high-purity ceramic working surface allowing wafer-free cleaning of the chamber and chuck. Maximum power up to 5 kilowatts can be applied to the plate.

It is suitable for deep and ultra-deep etching of high aspect ratio contacts in silicon oxide (FEOL - front end of line), e.g. for memory devices. This process is carried out at low plasma power and high RF displacement on a wafer with different masks: photoresist, amorphous carbon, silicon nitride, polysilicon. The highest speed of oxide etching in BEOL (back end of line) processes such as fuse (fuse, pad) is brought in production to 2.8 micrometers per minute.

On the other hand, the system enables atomic layer etch rate control up to 40-50 angstroms per minute at low bias power on the wafer, with ultimate speed uniformity across the wafer and uniformity of critical size structures.

Numerous applications, such as dissection and solid mask formation (oxide, nitride, polysilicon, amorphous carbon) and photoresist removal are standard processes of PC process specification.

A library of silicon speed etching processes for CMOS and MEMS applications is also available.

Device properties

In contrast to European R&D level small batch equipment manufacturers with uncontrolled cell contamination, the 300mm module has been industrially tested to SEMI standards. The 200mm PC version developed by ESTO is implemented with reliable mass production technology.

Vacuum chamber is made of anodized aluminum monoblock and has central evacuation provided by full symmetry of the working space, double thermostabilized chamber wall, which ensures high homogeneity and reproducibility of the processes. Plasma source is made of monocrystalline silicon, quartz or ceramics depending on the PC purpose.

A unique combination of properties of the Groovy ISP is its ability to independently and simultaneously set both physical and chemical process conditions in the radial direction.

"It is the only industrial source in the world that allows for simultaneous local control of plasma density and chemical composition along the radius of the wafer. Technologists are able to carry out processes with previously unattainable combinations of parameters: process rate gradient along the radius of the plate can be changed at invariable external discharge parameters (total RF power, pressure, gas flow rate). Thus, the widest possible process parameter window can be achieved and the process uniformity over the plate can be easily achieved. Furthermore, the PC allows for arbitrary concave and convex process velocity distributions across the plate," explained the company.

The PC is suitable for high-speed removal of photoresist after etching, and also has a self-cleaning function. Pulse control of both plasma density and positive ion energy is available.

The PC as a freestanding system can be equipped with a variety of vacuum plate loaders, including cassette plate loaders. The minimum variant is a manual loading gateway, the maximum variant is an automatic cluster system with one, two or three PCs and a front-end SMIF module.