---
title: "Carbon nanofibers in the semiconductor industry"
canonical_url: "https://www.smoltek.com/carbon-nanofibers-in-the-semiconductor-industry/3200/"
date: 2022-06-18
author: "Thomas Barregren"
featured_image: "https://www.smoltek.com/wp-content/uploads/2022/01/adobestock-165717610-jpg.webp"
categories:
  - name: "Semiconductor"
    url: "https://www.smoltek.com/category/articles/semiconductor.md"
tags:
  - name: "2.5"
    url: "https://www.smoltek.com/topic/2-5.md"
  - name: "3D"
    url: "https://www.smoltek.com/topic/3d.md"
  - name: "carbon nanotechnology"
    url: "https://www.smoltek.com/topic/carbon-nanotechnology.md"
  - name: "cnf"
    url: "https://www.smoltek.com/topic/cnf.md"
  - name: "cnf-mim"
    url: "https://www.smoltek.com/topic/cnf-mim.md"
  - name: "microbumps"
    url: "https://www.smoltek.com/topic/microbumps.md"
  - name: "thermal film"
    url: "https://www.smoltek.com/topic/thermal-film.md"
---

# Carbon nanofibers in the semiconductor industry

Based on our CNF-tech­nol­o­gy, we have devel­oped an assem­bly plat­form that push­es the lim­its for het­ero­ge­neous inte­gra­tion in 2.5D and 3D. The plat­form offers ultra-fine pitch microbumps, ultra thin ther­mal film for heat dis­si­pa­tion, ultra minia­tur­ized capac­i­tors inte­grat­ed direct­ly onto dies or embed­ded into inter­posers, and an inter­pos­er with built-in DC stor­age smooth­ing out vari­a­tions in pow­er supply.

![Ultra-fine pitch microbumps made of carbon nanofibers.](https://www.smoltek.com/wp-content/uploads/2022/01/carbon-nanofiber-microbumps-600x400.webp)

![Close-up of a wafer with Smoltek's carbon nanofiber metal-insulator-metal (CNF-MIM) capacitor—the world's thinnest capacitor.](https://www.smoltek.com/wp-content/uploads/2022/06/cnf-mim-wafer-01-1200x675-1.jpg)

We have also devel­oped [the world’s small­est capac­i­tor](https://www.smoltek.com/technologies/miniaturized-capacitors/). The total height is only 30 µm—which is less than half what is pos­si­ble with oth­er tech­nolo­gies. Its capac­i­tance is a whop­ping 650 nF/​mm2. Its inter­nal resis­tance (ESR) is less than 40 mΩ, and its inter­nal induc­tance (ESL) is below 15 pH.

We offer a tech­ni­cal part­ner­ship to man­u­fac­tur­ers who want to devel­op their offer in het­ero­ge­neous inte­gra­tion or pas­sive com­po­nents with our tech­nol­o­gy to short­en devel­op­ment time and min­i­mize risks. Are you inter­est­ed? [Con­tact us](https://www.smoltek.com/smoltek-semi/contact/) now to learn more.

![Smoltek team members in the lab.](https://www.smoltek.com/wp-content/uploads/2022/01/smoltek-in-the-lab-1200x800.webp)

## [](https://www.smoltek.com#what-are-semiconductors)What are semiconductors?

A mate­r­i­al is an elec­tri­cal *con­duc­tor* if an elec­tric field can move an elec­tron from one atom to the next. Only the elec­tron in the out­er­most shell around an atom­ic nucle­us can do that, and only if there is an even fur­ther out shell that it can jump to with ener­gy from the elec­tric field.

If the dis­tance between the out­er­most shell of elec­trons and the next shell is too great for elec­trons to jump out there, the sub­stance is an elec­tri­cal *insu­la­tor*.

For some mate­ri­als, such as sil­i­con, the gap is so small that some elec­trons can jump across the gap. When the elec­tron cross­es the gap, it leaves behind a *hole*. Under the influ­ence of an elec­tri­cal field, both the elec­tron and the hole can move across the mate­r­i­al. It con­ducts elec­tric­i­ty, but poor­ly. That’s why such a sub­stance is called *semi­con­duc­tor*.

The con­duc­tiv­i­ty can be dra­mat­i­cal­ly improved by adding impu­ri­ties in the form of oth­er sub­stances that add extra elec­trons or holes. This is called *n‑doping* and *p‑doping*, respec­tive­ly.

## [](https://www.smoltek.com#the-magic-at-the-p-n-junction)The magic at the p‑n-junction

A *p‑n-junc­tion* is where p‑doped semi­con­duc­tor meets n‑doped semi­con­duc­tor. At p‑n-junc­tions, the mag­ic hap­pens that makes mod­ern elec­tron­ics possible.

Because there is an excess of elec­trons in the n‑doped semi­con­duc­tor and a deficit of elec­trons (holes) in the p‑doped semi­con­duc­tor, elec­trons dif­fuse from the n‑doped to the p‑doped semi­con­duc­tor to reach equi­lib­ri­um. This cre­ates a region that is deplet­ed of elec­trons and holes that can car­ry cur­rent. Con­se­quent­ly, the region is said to be a *deple­tion region*.

By apply­ing a volt­age across the p‑n junc­tion one can cause the deple­tion region to increase (which blocks cur­rent from pass­ing) or decrease (which allows cur­rent to pass). This is what is exploit­ed in transistors.

## [](https://www.smoltek.com#how-transistors-work)How transistors work

A *tran­sis­tor* acts like an elec­tri­cal­ly con­trolled tap. By gen­tly turn­ing the tap, more or less flow can be cre­at­ed. This fea­ture is used in ana­log elec­tron­ics to ampli­fy sig­nals. By quick­ly turn­ing the tap on or off, “ones and zeros” are cre­at­ed in terms of cur­rent pass­ing or not. This is the foun­da­tion of all dig­i­tal elec­tron­ics, not least computers.

The first tran­sis­tor was cre­at­ed in Decem­ber 1947 at the Bell Tele­phone Lab­o­ra­to­ries. A cou­ple of years lat­er, what we today think of as a tran­sis­tor was invent­ed. It con­sists of n‑doped or p‑doped semi­con­duc­tors through which cur­rent is passed. The mid­dle part of the semi­con­duc­tor is replaced by a piece of semi­con­duc­tor of the oppo­site type. It cre­ates two p‑n junc­tions. By sup­ply­ing cur­rent through the mid­dle sec­tion, the width of the two deple­tion regions can be changed. Thus, a cur­rent through the mid­dle sec­tion con­trols how much of the cur­rent through the tran­sis­tor is allowed to pass. Since both neg­a­tive and pos­i­tive charges are mov­ing (elec­trons and elec­tron holes, respec­tive­ly), it is called *bipo­lar junc­tion tran­sis­tor* (*BJT*).

## [](https://www.smoltek.com#mosfet)MOSFET

A tran­sis­tor con­trolled by an elec­tric field instead of cur­rent is called a *field-effect tran­sis­tor* (*FET*). While the BJT always con­sumes pow­er, the FET con­sumes no pow­er when its tap is unchanged (e.g., on or off). That’s per­fect for cre­at­ing ener­gy-effi­cient dig­i­tal electronics.

The first field-effect tran­sis­tor was devel­oped in 1953. But it had prob­lems with leak­ag­ing cur­rent where p–n junc­tions inter­cept the surface.

In the late 1950s, Mohamed M. Atal­la of Bell Tele­phone Lab­o­ra­to­ries dis­cov­ered that a thin lay­er of insu­lat­ing sil­i­con diox­ide on top of a semi­con­duc­tor pre­vents leak­age cur­rent. But how to make elec­tric con­tact with a FET if an insu­lat­ing lay­er cov­ers its surface?

Mohamed M. Atal­la and his col­league Dawon Kah­ng ele­gant­ly solved this. They added met­al gates on top of the oxide lay­er where they want­ed the con­nec­tion. The stack of met­al, oxide, and semi­con­duc­tor form a par­al­lel-plate capac­i­tor. The met­al gate is one elec­trode, the semi­con­duc­tor under­neath is the oth­er elec­trode, and the thin sil­i­con diox­ide lay­er acts as the dielec­tric. The much improved FET was named *met­al-oxide-semi­con­duc­tor field-effect tran­sis­tor*, or *MOSFET* for short.

One of the MOS­FETs’ many ben­e­fits is that com­pared to BJTs they are rel­a­tive­ly easy to pro­duce. There­fore, it is bet­ter to use MOS­FETs in inte­grat­ed cir­cuits. Dawon Kah­ng point­ed this out in 1961.

## [](https://www.smoltek.com#integrated-circuit-ic-chip)Integrated circuit (IC)—chip

An *inte­grat­ed cir­cuit* (*IC*) is a set of elec­tron­ic cir­cuits on one small flat piece of semi­con­duc­tor called *chip*. The idea of com­bin­ing sev­er­al com­po­nents in one device goes back to 1949. But it wasn’t until a decade lat­er that the first IC in a mod­ern sense was fab­ri­cat­ed. It used bipo­lar junc­tion tran­sis­tors (BJT). The first chip with MOSFET was fab­ri­cat­ed in 1961.

MOS­FETs are supe­ri­or to BJTs in inte­grat­ed cir­cuits because they are eas­i­er to pro­duce and can be made much small­er. It took only two years after the first MOSFET chip was pro­duced before chips with MOSFET reached high­er tran­sis­tor den­si­ty and low­er man­u­fac­tur­ing costs than those with BJTs.

## [](https://www.smoltek.com#cmos)CMOS

In the late 1960s, the *com­ple­men­tary met­al-oxide-semi­con­duc­tor* (*CMOS*) was devel­oped. The name refers to both a par­tic­u­lar style of dig­i­tal cir­cuit­ry design, cre­at­ing dig­i­tal gates by com­bin­ing two MOS­FETs of oppo­site dop­ing, and a process used to imple­ment that cir­cuit­ry on inte­grat­ed cir­cuits (chips). Two impor­tant char­ac­ter­is­tics of CMOS devices are high noise immu­ni­ty and low sta­t­ic pow­er consumption.

## [](https://www.smoltek.com#chip-manufacturing-process)Chip manufacturing process

The pro­duc­tion of chips is a com­plex process that can take up to three months. Today, they are usu­al­ly man­u­fac­tured accord­ing to the fol­low­ing steps:

01. Extreme­ly pure sil­i­cone is pro­duced from quartzite or sand. The sil­i­cone is shaped into a cylin­dri­cal ingot with a diam­e­ter of up to 300 mil­lime­ters. The sil­i­con ingot is then sliced into discs; each disc is 0.75 mil­lime­ters thick and is called a *wafer*.
02. Sev­er­al thin lay­ers of insu­lat­ing, semi­con­duct­ing, and con­duct­ing mate­ri­als are placed on a wafer. Which mate­ri­als and in what order depends on what is to be pro­duced. This is called *depo­si­tion*.
03. The last lay­er applied is a *pho­tore­sist*—a sub­stance resis­tant to cor­ro­sive sub­stances except where it has been exposed to ultra­vi­o­let light.
04. The next step is *lith­o­g­ra­phy*. Deep ultra­vi­o­let (DUV) or extreme ultra­vi­o­let (EUV) light is sent through a ret­i­cle with the draw­ing of the pat­tern to be cre­at­ed. Lens­es or mir­rors are used to shrink and focus the pat­tern pro­ject­ed onto the pho­tore­sist. Where the light hits the pho­tore­sist, it los­es its resis­tance to cor­ro­sive sub­stances, while the resis­tance remains where the light has not hit.
05. Wafers are now placed in a chem­i­cal bath that erodes exposed pho­tore­sist while leav­ing the unex­posed pho­tore­sist unaf­fect­ed. This is called *wet etch­ing*. Instead of a bath, gas can also be used. This is called *dry etch­ing*. The result is that under­ly­ing lay­ers are uncov­ered where the light has hit while the rest is still shielded.
06. Once pat­terns are etched in the wafer, the wafer may be bom­bard­ed with pos­i­tive or neg­a­tive ions to dope uncov­ered semi­con­duc­tors. This is called *ion implan­ta­tion*.
07. Now, the remain­ing sec­tions of resist that were pro­tect­ing areas that should not be etched or ion­ized are removed.
08. Steps 2–7 are repeat­ed repeat­ed­ly until the desired func­tion­al­i­ty is achieved. Mod­ern chips can have up to two hun­dred lay­ers, which all need to align on top of each oth­er with extreme precision.
09. A wafer holds cir­cuits for many chips. How many cir­cuits depends on how large they are. Some wafers may con­tain thou­sands of cir­cuits, while oth­ers con­tain only a few dozen. The cir­cuits are cut out with a dia­mond saw. The cut-out pieces of the wafer are called *dies*.
10. The chip is now cre­at­ed by mount­ing the die on a sub­strate that acts as a back­plane with con­nect­ing wires.
11. Final­ly, the chip is put into a plas­tic pack­age with con­nect­ing pins.

![](https://www.smoltek.com/wp-content/uploads/2022/01/adobestock-444505498-1200x480.webp)

Sil­i­con wafer after the dic­ing process.

## [](https://www.smoltek.com#minimum-costs-per-transistor)Minimum costs per transistor

Although chip man­u­fac­tur­ing has been refined since the first MOSFET chips were pro­duced, not all dies will work. There­fore, each die must be test­ed (which is typ­i­cal­ly done before the wafer is diced). The per­cent­age that pass­es is called the *die yield*.

The cost per tran­sis­tor decreas­es with the num­ber of tran­sis­tors that fit on a chip to a point where the cost increas­es again due to decreas­ing yield. Thus there is an inflec­tion point where the cost per tran­sis­tor is the low­est possible.

In an arti­cle pub­lished in 1965 in Elec­tron­ics (Vol­ume 38, Num­ber 8), Gor­don E. Moore—co-founder of Fairchild Semi­con­duc­tor and lat­er Intel—referred to this opti­mal point as “min­i­mum com­po­nent costs.” More­over, he not­ed that in those few years that chips had been pro­duced, the num­ber of tran­sis­tors giv­ing min­i­mum com­po­nent costs had dou­bled each year. He pre­dict­ed that this growth rate would con­tin­ue for anoth­er ten years.

## [](https://www.smoltek.com#moores-law)Moore’s law

When he looked back at his pre­dic­tion in 1975, Moore, who now was CEO of Intel, found it was almost spot on. Instead of an expect­ed increase of 210, the increase was 29. In oth­er words, the num­ber of tran­sis­tors at the low­est price point dou­bled every 13 months.

At the 1975 *IEEE Inter­na­tion­al Elec­tron Devices Meet­ing*, Moore revised his fore­cast rate, pre­dict­ing that semi­con­duc­tor com­plex­i­ty would con­tin­ue to dou­ble annu­al­ly until about 1980, after which it would decrease to a rate of dou­bling approx­i­mate­ly every two years.

One of Moore’s friends, Dr. Carv­er Mead, a pro­fes­sor at Cal­tech, dubbed this revised pre­dic­tion as *Moore’s Law*.

## [](https://www.smoltek.com#houses-postulate)House’s postulate

In a sci­en­tif­ic paper pub­lished in 1974, the pow­er con­sump­tion of MOS­FETs was shown to decrease lin­ear­ly with the area they occu­py. This rela­tion­ship is called *Den­nard scal­ing*.

Dennard’s scal­ing makes it pos­si­ble to dou­ble the num­ber of tran­sis­tors with­out using more pow­er. And if no more pow­er is sup­plied, no more heat needs to be dis­si­pat­ed. Thus it is pos­si­ble to dou­ble the com­pu­ta­tion­al capac­i­ty by dou­bling the num­ber of tran­sis­tors with­out heat dis­si­pa­tion becom­ing a grow­ing prob­lem. This leaves room to increase the clock fre­quen­cy that sets the rate at which ones and zeros are turned off and on.

David House, an Intel exec­u­tive, real­ized that this and oth­er improve­ments make it pos­si­ble to increase com­put­ing capac­i­ty faster than the num­ber of tran­sis­tors. He, there­fore, pos­tu­lat­ed that the per­for­mance of a com­put­er chip dou­bles every eigh­teen months.

House’s pos­tu­lates are often mis­tak­en as Moore’s Law. But these are two sep­a­rate pre­dic­tions, albeit close­ly related.

## [](https://www.smoltek.com#is-moores-law-still-applicable)Is Moore’s law still applicable?

Does Moore’s law still apply? No, not as orig­i­nal­ly for­mu­lat­ed. Den­si­ty at min­i­mum cost per tran­sis­tor has long ceased to dou­ble every two years. How­ev­er, den­si­ty at *any* cost per tran­sis­tor still dou­bles every two years.

But even this more gen­er­ous inter­pre­ta­tion of Moore’s law will not last for­ev­er. Many indus­try experts believe that Moore’s law will cease to apply alto­geth­er as ear­ly as 2025.

Rea­sons for Moore’s law to cease are many. Obvi­ous­ly, tran­sis­tors can­not become small­er than the atoms that make them up. But even before that, prob­lems arise with quan­tum tun­nel­ing, where elec­trons jump through bar­ri­ers and cause cur­rent leak­age. Anoth­er prob­lem, which is already real, is par­a­sitic tran­sis­tors that cre­ate cir­cuits that shouldn’t be there.

## [](https://www.smoltek.com#does-it-matter)Does it matter?

Does it mat­ter that Moore’s law is com­ing to an end? Not per se, but its impli­ca­tions are profound.

The devel­op­ment of the Inter­net of Things (IoT), self-dri­ving cars, con­nect­ed homes, Vir­tu­al Real­i­ty (VR), and Arti­fi­cial Intel­li­gence (AI) increas­ing­ly demands high com­put­ing capac­i­ty in a small foot­print and at low pow­er con­sump­tion. For this devel­op­ment not to come to a halt with Moore’s law, oth­er solu­tions are need­ed than cram­ming more and more tran­sis­tors onto the same surface.

A fore­cast of what will hap­pen when Moore’s Law ceas­es to apply was giv­en to the semi­con­duc­tor indus­try around 2006 when Den­nard scal­ing broke down.

## [](https://www.smoltek.com#breakdown-of-dennard-scaling)Breakdown of Dennard scaling

The pow­er con­sump­tion of CMOS cir­cuits is pro­por­tion­al to the clock fre­quen­cy. His­tor­i­cal­ly, the tran­sis­tor pow­er reduc­tion afford­ed by Den­nard scal­ing allowed man­u­fac­tur­ers to raise clock fre­quen­cies from one gen­er­a­tion to the next with­out sig­nif­i­cant­ly increas­ing over­all cir­cuit pow­er consumption.

But around 2006, tran­sis­tors had shrunk­en so much the pow­er required to run them increased due to cur­rent leak­age. Increased pow­er con­sump­tion leads to increased heat gen­er­a­tion. And increased heat caus­es elec­trons to become more mobile, which can cause tran­sis­tors to turn on or off spon­ta­neous­ly, lead­ing to fatal fail­ures. Increased heat also increas­es leak­age cur­rent, which fur­ther increas­es pow­er con­sump­tion and the prob­lems that fol­low. In the worst case, this self-ampli­fi­ca­tion can lead to ther­mal runaway.

## [](https://www.smoltek.com#overcoming-the-dennard-scaling-breakdown)Overcoming the Dennard scaling breakdown

The break­down of Den­nard scal­ing prompt­ed a prob­lem that could only be par­tial­ly over­come with improved cool­ing. In the end, it was not rea­son­able to con­tin­ue increas­ing the clock speed. That’s why the clock fre­quen­cy of today’s micro­proces­sors is the same as fif­teen years ago. But the per­for­mance has increased any­way. How?

The solu­tion to over­come the break­down of Den­nard scal­ing was mul­ti-core proces­sors. Instead of increas­ing the speed at which a sin­gle pro­cess­ing unit exe­cut­ed instruc­tions, more units were added. These units, called cores, can work inde­pen­dent­ly with par­al­lel tasks. This increas­es the over­all per­for­mance of the processor.

The solu­tion when Moore’s law breaks down is kind of similar.

![AdobeStock_352217571](https://www.smoltek.com/wp-content/uploads/2022/01/adobestock-352217571-1200x375.webp)

## [](https://www.smoltek.com#system-in-package-sip)System-in-Package (SiP)

The final step in fab­ri­cat­ing inte­grat­ed cir­cuits is to place the chip into a plas­tic pack­age with con­nect­ing pins. In the begin­ning, each such pack­age con­tained only one chip. Even­tu­al­ly, two or more chips began to be placed in the same pack­age to cope with

- reduced sur­face area due to more and more to be packed into less and less space,
- reduced yield due to larg­er dies,
- lim­it­ed trans­mis­sion speed due to capac­i­tance in long wires, and
- pow­er loss­es due to par­a­sitic capac­i­tance in long wires.

It also allows the assem­bly of sim­pler chips into more com­plex solutions—like Lego. Last­ly, it enables a mix of chips with incom­pat­i­ble man­u­fac­tur­ing and pas­sive com­po­nents (e.g. condensers).

This approach is called *het­ero­ge­neous inte­gra­tion*, and the result is called a *Sys­tem-in-Pack­age* or *SiP* for short.

## [](https://www.smoltek.com#2d-ic)2D IC

The eas­i­est way is to assem­ble a SiP is to place two or more dies next to each oth­er on the same sub­strate. The dies are inter­con­nect­ed with each oth­er through wires in the sub­strate. The sub­strate also pro­vides an exter­nal con­nec­tion through tiny globes of solder—called *sol­der bumps*.

A die can be mount­ed face up. Then the die is con­nect­ed to the inter­con­nec­tions and the sol­der bumps with wires.

More com­mon is to mount a die face down. In this case, the die itself has micro­scop­ic sol­der globes—called *microbumps*—that come into con­tact with pads on the top of the sub­strate. These pads are, in turn, con­nect­ed to the substrate’s inter­con­nec­tions and sol­der bumps.

This form of SiP is called *2D IC* (two-dimen­sion­al inte­grat­ed cir­cuit) because the dies are mount­ed in a sin­gle plane. It is also known as *mul­ti-chip mod­ule* (*MCM*).

![](https://www.smoltek.com/wp-content/uploads/2022/01/2d-1200x233.png)

## [](https://www.smoltek.com#2-5d-ic)2.5D IC

The next step up in SiP-com­plex­i­ty is called *2.5D IC* (two and a half-dimen­sion­al inte­grat­ed cir­cuit). The name comes from the fact that dies are still side by side, but now face down on an inter­me­di­ate lay­er of silicon—called *inter­pos­er*. An inter­pos­er has pads on its top and microbumps on its bot­tom. Hor­i­zon­tal elec­tri­cal con­nec­tions inside the sil­i­con inter­con­nect some pads. Some are con­nect­ed to microbumps by a ver­ti­cal elec­tri­cal con­nec­tion run­ning through the silicon—called *through sil­i­con via* or *TSV* for short.

So what’s the point of adding an inter­pos­er? An inter­pos­er gen­er­al­ly reroutes con­nec­tions from one con­fig­u­ra­tion and pitch to anoth­er con­fig­u­ra­tion and pitch. But this is not the pri­ma­ry rea­son for their use in 2.5D ICs; the same goal can be achieved with wires on the sub­strate in 2D ICs. It is the use of sil­i­con that makes them worthwhile.

The fab­ri­ca­tion tech­niques used for sil­i­con allow elec­tri­cal con­nec­tions much fin­er than fea­si­ble on com­mon sub­strates. More­over, we are not con­strained to con­nec­tions hor­i­zon­tal­ly but can also make them ver­ti­cal­ly. Thus, we can cre­ate many inter­con­nec­tions with­out a larg­er foot­print or adding much height. In turn, this means short­er sig­nal paths that enable high­er trans­mis­sion rates and reduce pow­er losses.

In addi­tion, sil­i­con expands much less when heat­ed than com­mon sub­strates. More impor­tant­ly, it expands like the dies mount­ed on top, whose microbumps must align per­fect­ly with the pads they con­nect to.

![](https://www.smoltek.com/wp-content/uploads/2022/01/25d-1200x317.png)

## [](https://www.smoltek.com#3d-ic)3D IC

The most com­plex SiP uses dies on top of each oth­er. This is called *3D IC* (three-dimen­sion­al inte­grat­ed circuit).

In its sim­plest form, one die is mount­ed on the top of anoth­er die, with the low­er die employ­ing through-sil­i­con vias (TSVs) to allow the upper die to con­nect to the low­er die and to the substrate.

![](https://www.smoltek.com/wp-content/uploads/2022/01/3d-1200x433.png)

In the gen­er­al case, a 3D IC con­sists of mul­ti­ple dies stacked on top of each oth­er using TSVs, and mul­ti­ple stacks of dies inter­con­nect­ed through a sil­i­con inter­pos­er. In jets, this is some­times called 5.5D IC since it com­bines the tech­niques of 2.5D and the sim­plest ver­sion of 3D.

![](https://www.smoltek.com/wp-content/uploads/2022/01/55d-1200x433.png)

## [](https://www.smoltek.com#benefits-of-sip)Benefits of SiP

A sys­tem-in-pack­age (SiP) is the result of het­ero­ge­neous inte­gra­tion. Sim­ple dies are put togeth­er like Lego pieces to form com­plex sys­tems. As we have already not­ed, SiP pro­vides less foot­print, increased yield, increased trans­mis­sion speed, and less pow­er loss. Tak­en togeth­er, this opens the door to con­tin­ued rapid growth in per­for­mance per unit area despite the lit­er­al mean­ing of Moore’s law ceas­ing to apply.

How­ev­er, it is not enough to open the door; we must also get through it.

## [](https://www.smoltek.com#whats-next)What’s next?

Sev­er­al things need to be addressed to main­tain con­tin­ued rapid growth in per­for­mance per unit area. In particular,

- more con­nec­tors are need­ed for each die to han­dle more data,
- heat must be dis­si­pat­ed from each die to avoid mal­func­tion, and
- decou­pling capac­i­tors must be placed as close to each die as pos­si­ble to avoid interference.

These are chal­lenges that put bound­aries for what is pos­si­ble with het­ero­ge­neous inte­gra­tion. And we have accept­ed the challenge.

## [](https://www.smoltek.com#pushes-the-boundaries-of-heterogeneous-integration)Pushes the boundaries of heterogeneous integration

Smoltek devel­ops tech­nolo­gies to fab­ri­cate nanos­truc­tures. In par­tic­u­lar, we are focus­ing on [car­bon nanofibers (CNFs)](https://www.smoltek.com/technologies/carbon-nanofibers/), which have many valu­able prop­er­ties. They are very stiff and strong. They are good con­duc­tors of heat and elec­tric­i­ty. And the con­tact sur­face where they stand increas­es a thousandfold.

A sig­nif­i­cant part of Smoltek’s research and devel­op­ment has been com­mit­ted to over­com­ing the chal­lenges of het­ero­ge­neous inte­gra­tion. We have also com­mit­ted our­selves to devel­op a fab­ri­ca­tion tech­nol­o­gy that is process com­pat­i­ble with CMOS. The latter’s chal­lenge is the rel­a­tive­ly low tem­per­a­tures used in CMOS fab­ri­ca­tion. We are pleased to say that we have deliv­ered on our commitments.

## [](https://www.smoltek.com#smolteks-achievements)Smoltek’s achievements

We have developed

- microbumps with ultra-fine pitch (< 5 µm),
- ultra thin ther­mal film for heat dissipation,
- an inter­pos­er with built-in DC stor­age smooth­ing out vari­a­tions in pow­er supply,
- a capac­i­tor direct on die or embed­ded in interposers

These achieve­ments form the cor­ner­stones on which we have built *Smoltek Tiger*—an assem­bly plat­form con­cept for het­ero­ge­neous inte­gra­tion and advanced pack­ag­ings such as 2.5D and 3D SiP.

Of these achieve­ments, we are most excit­ed about our capac­i­tor, which has the world’s small­est foot­print (650 nF/​mm2) and low­est build height (0.5–10 µm). Its inter­nal resis­tance (ESR) is less than forty mil­liohms (40 mΩ), and its inter­nal induc­tance (ESL) is below fif­teen pico­hen­ry (15 pH). So, of course, we also want to make this tech­nol­o­gy avail­able as a reg­u­lar dis­crete component.

[![Carbon nanofiber microbump.](https://www.smoltek.com/wp-content/uploads/2021/12/image-023-600x400.webp)](https://www.smoltek.com/wp-content/uploads/2021/12/image-023.jpg)

Car­bon nanofiber microbump.

[![Carbon nanofiber thermal film.](https://www.smoltek.com/wp-content/uploads/2022/01/cnf-thermal-film-600x400.webp)](https://www.smoltek.com/wp-content/uploads/2022/01/cnf-thermal-film.jpg)

Car­bon nanofiber ther­mal film.

[![scanning-electron-microscope-image-carbon-nano-fibre-metal-insulator-metal-cnf-mim-capacitor-including-substrate](https://www.smoltek.com/wp-content/uploads/2021/11/scanning-electron-microscope-image-carbon-nano-fibre-metal-insulator-metal-cnf-mim-capacitor-including-substrate-600x400.webp)](https://www.smoltek.com/wp-content/uploads/2021/11/scanning-electron-microscope-image-carbon-nano-fibre-metal-insulator-metal-cnf-mim-capacitor-including-substrate.jpg)

Car­bon nanofiber met­al-insu­la­tor-met­al capacitor.

## [](https://www.smoltek.com#ultra-miniaturized-discrete-capacitors)Ultra-miniaturized discrete capacitors

Capac­i­tors are essen­tial in all elec­tron­ics. They store ener­gy, atten­u­ate tran­sients, dis­si­pate inter­fer­ence, and more. They are indis­pens­able. Not least inside and out­side inte­grat­ed circuits.

We have there­fore focused in par­tic­u­lar on devel­op­ing our ultra-minia­tur­ized capac­i­tor and mak­ing it avail­able as a dis­crete com­po­nent that can be

- mount­ed on chip die,
- embed­ded in chip interposer,
- mount­ed on chip interposer,
- embed­ded in print­ed cir­cuit board (PCB), and
- mount­ed on PCB.

The total height, includ­ing cap­sule, is only 30 µm—which is less than half what is pos­si­ble with oth­er technologies.

The most amaz­ing thing about this micro­scop­ic capac­i­tor is its per­for­mance. One square mil­lime­ter has a capac­i­tance of a whop­ping 650 nF/​mm2. Its inter­nal resis­tance (ESR) is less than 40 mΩ, and its inter­nal induc­tance (ESL) is below 15 pH.

We describe our capac­i­tor as a *CNF-MIM capac­i­tor* since it is a met­al-insu­la­tor-met­al (MIM) capac­i­tor where [car­bon nanofibers (CNF)](https://www.smoltek.com/technologies/carbon-nanofibers/) are used to cre­ate a much larg­er sur­face area hence high­er capac­i­tance than the form fac­tor suggest.

Read the ded­i­cat­ed page about [Smoltek’s CNF-MIM capac­i­tor](https://www.smoltek.com/technologies/miniaturized-capacitors/) for more information.

![](https://www.smoltek.com/wp-content/uploads/2022/01/waffer-with-smolteks-cnf-mim-capacitors.jpg)

Close-up of a wafer with Smoltek’s car­bon nanofiber met­al-insu­la­tor-met­al (CNF-MIM) capacitor—the world’s thinnest capacitor.

## [](https://www.smoltek.com#interested-in-our-technology)Interested in our technology?

Smoltek’s busi­ness mod­el is not to man­u­fac­ture semi­con­duc­tors nor capac­i­tors but to license our fab­ri­ca­tion tech­nol­o­gy to lead­ing sup­pli­ers of such products.

We offer a long-term tech­ni­cal part­ner­ship, where we con­tribute our tech­nol­o­gy which we have invest­ed mon­ey and time in devel­op­ing at our per­il, for the ben­e­fit of our part­ner, thus short­en­ing the devel­op­ment time and min­i­miz­ing the risks. We also offer know-how, tai­lor-made solu­tions, pro­duc­tion of test series, and advice and assis­tance in imple­ment­ing the man­u­fac­tur­ing process.

Are you inter­est­ed in part­ner­ing with us? [Con­tact us](https://www.smoltek.com/smoltek-semi/contact/) today, and let’s arrange a meet­ing to dis­cuss it further.