Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Etching of deep trenches in silicon explained

05.02.2004


Dutch researcher Michiel Blauw has described the physical limitations of the plasma-etching of deep, narrow microstructures in silicon. His results have led to such an improvement in the etching process that trenches with a depth more than 30 times their width can now be made. This is important for the production of sensitive sensors.



Blauw investigated fluorine-based plasma etching processes. A plasma with a high ion-density ’burns’ a small hole in silicon. Many applications require narrow, deep holes. Blauw studied how the plasma reacts with the silicon and how the sidewalls must be treated so as to make the trench as deep and as straight as possible.

The researcher came up with two ways to improve the profile of the trenches in the so-called Bosch process. During this process, a polymer layer ensures that the sidewalls are not etched by the plasma. However, the thin polymer layer is also deposited onto the bottom of the trench and this hinders the etching of deep, narrow trenches.


Firstly the researcher added a third plasma pulse to the Bosch-process after the etching and passivation pulses. This efficiently removed the polymer layer from the bottom of the trench. A patent has been granted for this method. Secondly he optimised the passivation pulse used to treat the sidewalls so that no polymer deposition occurred on the bottom of the trenches.
This made a maximum depth-width ratio of more than 30 possible.

In principle, the etching of silicon occurs at the same speed in all directions. To obtain the deep, narrow trenches necessary for accurate sensors, the sidewalls must be made insensitive to the plasma. This is termed passivating. After a variety of experiments in which he added oxygen to the plasma or deposited a polymer layer, Blauw found an effective passivating technique. A plasma with a high ion-density removes the passivating layer from the surface. This results in deep, narrow trenches because the ions are accelerated perpendicular to the substrate. He also found that the etch rate as a function of the depth-width ratio can be controlled by tuning the ion-density.

Plasma-etching provides considerable advantages for the manufacture of inertial sensors such as accelerometers and gyroscopes. This is because the manufacturing processes for the sensor and the electronics for signal processing are compatible, allowing both parts to be integrated onto a single chip. Furthermore, increasing the depth-width ratio of the etched microstructures considerably improves the integration density and accuracy of these devices.

The research was funded by the Technology Foundation STW.

Sonja Jacobs | NWO
Further information:
http://www.nwo.nl

More articles from Materials Sciences:

nachricht Move over, Superman! NIST method sees through concrete to detect early-stage corrosion
27.04.2017 | National Institute of Standards and Technology (NIST)

nachricht Control of molecular motion by metal-plated 3-D printed plastic pieces
27.04.2017 | Ecole Polytechnique Fédérale de Lausanne

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>