Everything you need to know about TEPHRA™

(and why you should care about another ALD cluster tool)

Driven by new device functionality in the More-than-Moore era, the past decade has seen a surge of activity from ALD companies in the semiconductor space. This has resulted in a crowded market of cluster tools that can be difficult to discern.

This time is different.

From supercharged hardware to ingenious chemistry, every facet of TEPHRA is designed to impart the purest ALD manufacturing experience possible. We have put some of the best minds in the world together to bring the semiconductor industry something unique and innovative for the next era of device fabrication.

To help you get familiar with the new tool, we’ve compiled everything you need to know about what sets TEPHRA apart from the rest of the field.

Atomic Layer Deposition cluster tool for 200 mm wafer processing

Higher Throughputs

Improved Precursor Efficiencies

New Chemistry Options

Less Maintenance

Render of an eight-sided TEPHRA with four process modules, two cassette modules and one transfer module. This configuration can accommodate up to six process modules. TEPHRA is also available on four and six-sided platforms for lower volume processing needs.

1. High Throughput Single-Wafer Processing

First and foremost, TEPHRA is a single-wafer atomic layer deposition (ALD) tool that we view as an homage to the roots of ALD in the semiconductor industry. It

Single-wafer processing in cross flow reactors was the original strategy by ALD tool manufacturers. It offered high yield and low risk for the industry’s most precious depositions. Tool manufacturers eventually started moving to batch tools to accommodate low deposition rates and achieve higher throughputs, but this led to a tradeoff between speed and yield risk.

TEPHRA is unique in that it breaks the fundamental tradeoff of single-wafer processing by offering high chemical utilization at high throughputs.

But to fully understand what makes TEPHRA so different, we must look a bit deeper at what’s happening inside.

2. Superior Precursor Efficiency

Most ALD tools struggle with poor precursor efficiency. Typically, manufacturers must choose either efficient chemical utilization at high reactor pressures or fast purges at low reactor pressures. Since the cost of time often outweighs the cost of chemicals, most tools run at low pressure, dumping unused precursor down the pump.

To break this compromise, TEPHRA utilizes a process called Synchronously Modulated Flow and Draw (ALDx technology. It’s because of this process that TEPHRA can reach precursor efficiencies of 90% and rapidly process single wafers.

So how exactly does it work?

Inside the reaction chamber, a gas curtain surrounds the wafer area during reactant exposures. This creates an area of high pressure above the wafer and mimics a large exposure with a small chemical dose. It’s this high-pressure regime that allows TEPHRA to achieve extremely high chemical efficiency with process reactants.

When the exposure is finished, the gas curtain is turned off, reopening the wafer space to vacuum and quickly purging out the miniscule amounts of excess reactant and byproduct. Release of the gas curtain creates a high flow situation found in low reactor pressure environments, resulting in purge times less than 0.5 seconds.

SMFD is a core feature of TEPHRA’s processing technology, allowing processes to reach nearly 90% precursor efficiency and sub-one second cycle times. And it’s only the first part of the ALDx technology that makes TEPHRA stand out amongst the rest.

Benefits of an ALD cluster tool for semiconductor manufacturing

TEPHRA is equipped with Forge Nano’s ALDx technology, the fastest, most efficient ALD platform for semiconductor manufacturing.

3. Proprietary ALD Components

It is known that ALD is the most precise deposition technique ever invented. It makes sense then that the hardware to perform it to its fullest potential must also be as precise as possible. On TEPHRA’s gas lines are our proprietary Fast Pneumatic Valves (FPVs) that were specifically designed for performing rapid ALD.

Our FPVs have an industry-best actuating time of 1 millisecond, capable of performing hundreds of thousands of ALD cycles and dosing extremely precise amounts of precursor. FPVs are crucial for enabling high precursor efficiency by ensuring reactants are not wastefully overdosed. It also allows us to inject vanishingly small amounts of catalyst during our CRISP reactions (more to come on this) to prevent issues with surface poisoning or film contamination.

Every millisecond counts in the . FPVs save time and material – giving manufacturers control over their process and their wallet.

Valves this precise cannot be found in any other ALD tool, nor can the next aspect of TEPHRA on the list.


4. Catalyzed Thermal ALD

TEPHRA is not only equipped with clever engineering but also with clever chemistry. Most ALD tools utilize plasma to perform low temperature depositions or for materials that are difficult to deposit. While an effective technique, plasma hardware can be complex and expensive, and the directionality of plasma depositions make them difficult to scale, especially for applications requiring films in high aspect ratio structures.

TEPHRA, instead, uses catalyzed thermal ALD reactions that we refer to as CRISP (Catalyzing Reactions for Induced Surface Process). CRISP reactions work by dosing a small amount of non-metal during each half-cycle. The catalyst helps push the reaction forward, serving a similar role to plasma in the process. The technique also offers numerous chemical knobs able to tune the properties of the resulting film, rivaling and often surpassing the results of plasma depositions.

With catalyzed ALD, device manufacturers can deposit oxides, nitrides and metals at low temperatures, achieving high performance properties without conformality limits. In fact, we are launching TEPHRA with a flagship Metal Barrier Seed application, , to enable the fabrication of through silicon and through glass vias with aspect ratios greater than 10:1, previously unattainable with traditional directional deposition methods.


Copper electroplated in a 4:1 trench coated with a metal barrier seed stack made by ALD

Copper-electroplated trenches with an aspect ratio of 4:1 show excellent metal wetting and no void formation following the deposition of an all-ALD metal barrier seed stack by CRISP.

5. Easier and Less Frequent Maintenance

To wrap up, let’s discuss one of the most important activities of ALD tool ownership: cleaning and preventative maintenance. These activities are imperative to keeping equipment well-functioning and high-performing. Unfortunately, frequent maintenance cycles and difficult cleaning procedures often breed complacency, making it easy to push the chores to the last minute.

Thankfully, TEPHRA is designed to make maintenance as easy and as infrequent as possible, so more time is spent manufacturing cutting-edge technology and less spent cleaning.

First, the gas curtain used for SMFD does an excellent job limiting precursors from reaching the chamber walls. Rather than getting pesky deposition inside the reactor, gases stay above the wafer where they should be.

Next, TEPHRA utilizes replaceable liners that provide protection from precursor gases. These are similar to the usual reactor liners, but are much smaller, less expensive and easier to service, making replacement a quick and painless process.

Finally, TEPHRA is equipped with an integrated abatement system between the deposition zone and pump that assists in breaking down unused chemicals and by-products before it reaches the vacuum equipment. By preventing the buildup of waste residue in vacuum lines and pumps, service becomes faster and safer, and pump lifetimes are extended.

So that is everything you need to know about what makes TEPHRA unique. We wanted TEPHRA to represent ALD manufacturing in its purest form. The tool is designed to exemplify the elegance of ALD, reflect its merits of precision and quality, and solidify its continuing reputation as an enabling technology 50 years after its inception. We believe it was worth the wait.

But don’t just read about it, let us show you! If you would like more information about demoing your process or how TEPHRA can elevate your fab’s equipment fleet, please contact us for a consultation with our experts.