Deep Trench Capacitors (DTC) is a dead end – CNF-MIM is the way forward

Think about the smart­phone in your pock­et. It’s a mar­vel of engi­neer­ing, packed with incred­i­ble com­put­ing pow­er, all thanks to a myr­i­ad of tiny com­po­nents. Among these unsung heroes are capac­i­tors, which store and release elec­tri­cal ener­gy to keep every­thing run­ning smooth­ly. But the indus­try is nev­er sat­is­fied, always want­i­ng more capac­i­tance in less space. This has led to a race to find new capac­i­tor tech­nolo­gies. For a while, the deep trench capac­i­tor (DTC) tech­nol­o­gy looked promis­ing. But now they are approach­ing the lim­its of what physics will allow, and the indus­try is still not sat­is­fied. For­tu­nate­ly, a new con­tender has emerged: car­bon nanofiber met­al-insu­la­tor-met­al (CNF-MIM) capac­i­tors. CNF-MIM capac­i­tors don’t have the inher­ent lim­i­ta­tions of DTC, but instead point the way for­ward to even more capac­i­tance in even less volume.

Subtractive vs. additive: two ways of creating

To under­stand why DTC tech­nol­o­gy faces inher­ent lim­i­ta­tions while CNF-MIM rep­re­sents the future, let’s pic­ture two dis­tinct ways of cre­at­ing. DTC is like carv­ing a sculp­ture from a block of mar­ble – it’s a sub­trac­tive process. You start with the mate­r­i­al and remove what you don’t need. In con­trast, CNF-MIM is like sculpt­ing with clay – an addi­tive process. Here, you build up a struc­ture lay­er by lay­er, adding mate­r­i­al pre­cise­ly where needed.

The DTC jour­ney starts with a sil­i­con wafer. From that sur­face, pre­cise process­es cre­ate deep trench­es, like minia­ture wells in the ground. These trench­es are then care­ful­ly filled with dif­fer­ent mate­ri­als to form a capac­i­tor. While this approach has pushed the bound­aries of what’s pos­si­ble, it’s run­ning into phys­i­cal bar­ri­ers. It’s like a sculp­tor try­ing to carve an impos­si­bly intri­cate design from an ever-small­er block of marble.

The physical limits of DTC

The crux of the prob­lem with DTC lies in the physics of its creation.

To increase capac­i­tance den­si­ty, that cru­cial mea­sure of how much elec­tri­cal charge can be stored in a giv­en space, man­u­fac­tur­ers aim to cre­ate deep­er, nar­row­er, and more numer­ous trench­es. Capac­i­tance is direct­ly pro­por­tion­al to the sur­face area, so deep­er trench­es cre­ate more wall area, increas­ing capac­i­tance. More trench­es increase the over­all area. Addi­tion­al­ly, capac­i­tance is inverse­ly pro­por­tion­al to the dis­tance between the walls. There­fore, nar­row­er trench­es bring the walls clos­er, increas­ing capacitance.

How­ev­er, there’s a prac­ti­cal lim­it to how deep and nar­row these trench­es can be. Uni­form coat­ing of mate­ri­als becomes hard­er and the risk of short cir­cuits or unac­cept­able leak­age cur­rent increases.

As these trench­es reach their phys­i­cal lim­its, the abil­i­ty to improve DTC per­for­mance rapid­ly decreas­es. Returns dimin­ish with each attempt to make the trench­es more aggres­sive. Imag­ine try­ing to paint the inside of a straw with a brush, and at the same time mak­ing that straw thin­ner and longer. It quick­ly becomes impos­si­ble. Also, the struc­ture becomes more frag­ile with deep­er and more numer­ous trenches.

CNF-MIM: Building the future, layer by layer

Now let’s look at the Smoltek CNF-MIM process. It is a rad­i­cal depar­ture from the sub­trac­tive meth­ods used in tech­niques such as DTC.

Instead of dig­ging trench­es, CNF-MIM is man­u­fac­tured by putting incred­i­bly thin car­bon nanofibers ver­ti­cal­ly on the sub­strate. Think of it as a for­est of micro­scop­ic trees. These fibers, which are 10,000 to 15,000 times thin­ner than a human hair, are metic­u­lous­ly coat­ed, each with a thin lay­er of met­al, fol­lowed by a thin lay­er of insu­lat­ing mate­r­i­al, and then anoth­er lay­er of met­al. This cre­ates a met­al-insu­la­tor-met­al capac­i­tor at the nanoscale. These lay­ers can also be repeat­ed for mul­ti­lay­er capac­i­tor structures.

By mak­ing the nanofibers long, a large sur­face area is obtained with­in a small foot­print. By cre­at­ing a dense for­est of fibers, this area is mul­ti­plied many times over. In this way, very high capac­i­tance can be achieved with­out increas­ing the volume.

A transformative advantage

The advan­tage is trans­for­ma­tive. Where DTCs strug­gle with depth and width ratios in their trench­es, CNF-MIM effort­less­ly achieves much high­er aspect ratios because its struc­tures are added rather than sub­tract­ed. It’s like the dif­fer­ence between dig­ging a ditch and build­ing a sky­scraper. This foun­da­tion­al dif­fer­ence means CNF-MIM capac­i­tors can poten­tial­ly achieve a vast­ly greater capac­i­tance den­si­ty than is phys­i­cal­ly pos­si­ble with DTC technology.

The future of capacitors is here

As we look to the future of elec­tron­ics, the lim­i­ta­tions of DTC tech­nol­o­gy become increas­ing­ly appar­ent. The indus­try needs a solu­tion that can scale beyond cur­rent phys­i­cal con­straints. CNF-MIM tech­nol­o­gy pro­vides just that. Its addi­tive man­u­fac­tur­ing approach unlocks pos­si­bil­i­ties that are sim­ply unat­tain­able with sub­trac­tive methods.

The poten­tial of CNF-MIM tech­nol­o­gy was high­light­ed in an inter­view with Dr. Philip Less­ner. His assess­ment acknowl­edged the ground­break­ing capa­bil­i­ties of Smoltek’s CNF-MIM capac­i­tors. This expert val­i­da­tion under­scores the indus­try’s grow­ing inter­est in addi­tive man­u­fac­tur­ing and the rev­o­lu­tion­ary poten­tial of CNF-MIM technology.

A clear path forward for Smoltek

For Smoltek share­hold­ers and investors, the impli­ca­tions of this shift are clear. DTC tech­nol­o­gy, while an impres­sive feat of engi­neer­ing, rep­re­sents a dead end in capac­i­tor devel­op­ment. The future belongs to inno­v­a­tive solu­tions like CNF-MIM that tran­scend cur­rent phys­i­cal limitations.

As the elec­tron­ics indus­try con­tin­ues its relent­less pur­suit of minia­tur­iza­tion and enhanced per­for­mance, the demand for high­er-per­form­ing capac­i­tors will only inten­si­fy. CNF-MIM tech­nol­o­gy not only meets these cur­rent chal­lenges but also pro­vides a clear path­way for future advance­ments. It’s not just a tem­po­rary solu­tion but a long-term answer to one of the most press­ing chal­lenges fac­ing the elec­tron­ics industry.

CNF-MIM isn’t just about bet­ter capac­i­tors; it’s about the future of elec­tron­ics. As a Smoltek investor, you’re a part of build­ing it.