ALD System Specifications v4.pdf

ALD SYSTEM SPECIFICATIONS N00173-21-SSN-TL14 PAGE 1 OF 11

SPECIFICATIONS FOR ATOMIC LAYER DEPOSITION (ALD) REACTOR WITH

MULTIPLE PRECURSOR DELIVERY PORTS, INTEGRATED IN-SITU

ELLIPSOMETER, AND SINGLE WAFER TRANSFER SYSTEM

I. GENERAL SPECIFICATIONS

A. The required system is a configurable atomic layer deposition (ALD) reactor for the uniform and conformal depositions of oxide, nitride, and metal films with atomic-layer precision onto substrates of high aspect ratio surface topographies.

B. The reactor shall consist of a single hot-walled, viscous flow reaction chamber that is serviced by gas handling, vacuum, and AC heating systems, and is capable of operating in both traditional thermal atomic layer deposition (ALD) and plasma enhanced ALD (PEALD) modes.

C. The system shall be integrated with an automated load lock system for advanced process control, and particulates of ALD byproducts must be prevented from entering the user loading zone and sample loading area.

D. The reactor shall focus precursor at the sample surface and will not contain parts mechanically actuated during processing so as to prevent flaking of ALD particulates onto the substrate surface.

E. The reactor shall accommodate at least 8 precursor ports (with the ability to upgrade to at least 12 precursors) and at least 4 gas lines (with the ability to upgrade to additional gases in the future as required).

F. Additionally, the reactor shall have an integrated in-situ ellipsometer that will provide real-time structural analysis of deposited films.

G. The reactor shall also include additional diagnostic ports for chemical analysis and leak testing leading to advanced process control.

H. The reactor shall be modular so that the system can be upgraded in the future for additional sources, chambers, gloveboxes, pumps, and diagnostic ports.

I. Tthe ALD reactor and the ellipsometer shall be computer controlled.

J. The reactor shall have an integral safety system.

K. Size Constraints—Due to space constraints, the system, including the enclosure, load lock, and loading mechanism (but excluding the control computer console) shall fit within 100” length, 40” width, and 84” height.

II. PERFORMANCE REQUIREMENTS

A. The Contractor shall document the successful manufacture, installation, and operation of an atomic layer deposition reactor of the type described in the General and Detailed Specifications for the growth of thermally deposited Al2O3, HfO2, and plasma deposited AlN.

B. The Contractor shall perform testing at the factory on the actual equipment to be installed at NRL to demonstrate the following:

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1. No leaks in the reactor tubing and seals as detected by a calibrated helium leak detector (supplied by NRL) down to > 10-9 Torr-l/s;

2. Base pressure in the range of 10-2 Torr

3. Process gas flows stable within ± 3% at flow rates characteristic of process conditions, for a period of two hours

4. Substrate heater temperature elevated to above 400oC and stable within ± 4% with an argon flow of approx. 800-1100 standard centimeters per minute for a period of two hours.

5. Delivery line temperatures and valve assemblies (All source lines, chamber lid, MFCs, and isolation valves) maintaining temperature uniformity ≤ ± 5.5% with an argon flow of approx. 18-25 standard centimeters per minute for a period of two hours.

C. In addition, the Contractor shall demonstrate the performance of the actual reactor to be installed at NRL, by growing the following layers in it on 150 mm Si wafers:

1. Al2O3 film greater than 100 nm thick with thickness variation of ≤ ± 3% or better, excluding a 10 mm exclusion zone from the edge of the wafer using both thermal and plasma enhanced ALD. The index of refraction of these films shall be ≥ 1.60 with uniformity ≤ ± 2.0% or better at a wavelength of 633nm.

2. HfO2 film greater than 100 nm thick with thickness variation of ≤ ± 3% or better, excluding a 10 mm exclusion zone from the edge of the wafer using thermal ALD.

The index of refraction of these films shall be ≥ 2.00 with uniformity ≤ ± 2.0% or better at a wavelength of 633nm.

3. AlN greater than 100nm thick film with thickness variation of ≤ ± 5% or better uniformity, excluding a 10 mm exclusion zone from the edge of the wafer using plasma enhanced ALD. The index of refraction of these films shall be ≥ 1.92 with uniformity ≤ ± 2.0% or better at a wavelength of 633nm. Films must contain low oxygen content ≤ 2.5%, as measured by XPS.

D. The Contractor shall verify after installation on site at NRL that no significant damage has occurred in transport or installation by repeating the factory tests dictated in Performance Requirements 2 and 3 and demonstrating results remain within these specifications

E. NRL will provide acceptance testing of said films through a combination of ellipsometry, x-ray photoelectric spectroscopy (XPS) and atomic force microscopy or step-profilometry measurements.

F. The ellipsometer shall be tested separately from the ALD-load lock system by a designated Sub-contractor provided by the original Contractor for compliance with specifications found in Detailed Integrated In-situ, Deep-UV to Near IR Ellipsometer Specifications.

G. The Contractor shall provide factory testing and compliance results from the actual system to be installed at NRL and a Certificate of Compliance guaranteeing that all the

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requirements of this specification have been met.

III. ALD REACTOR SPECIFICATIONS

A. ALD REACTOR CHAMBER

1. The reactor chamber shall be constructed of stainless steel consistent with commercial high vacuum processes and must be copper-free. It is preferred to have a single chamber reactor integrated with four separate chamber inlets for precursor delivery (not including plasma). The design should allow for rapid heating of samples, efficient vapor and gas delivery, and straightforward in situ real-time analysis of deposition (via ellipsometry, QCM, RGA, etc.).

2. The use of shutters can disrupt gas flow and cause formation and shedding of particulates that degrade the uniformity and purity of the deposited film. Therefore, the chamber must not use mechanical isolation devices to shutter the plasma source nor to protect port windows from unwanted film deposition.

3. The chamber shall have at least two ports directed at the projected loaded sample surface with ideal take-off angles (65o – 75o) for in situ ellipsometry measurements and one dedicated valve port for easy helium mass spectrometer leak detection.

4. The reactor chamber must be heated to achieve hot wall operation. Reactor wall temperatures up to 250oC shall be possible. The reactor lid and precursor inputs shall maintain heating uniformity ≤ ±6%, preferably by cladding them with aluminum blocks. The reactor chamber, lid, and exhaust must be independently actively heated in order to create a thermal gradient, thereby avoiding cold spots within the system that could be a potential cause for condensation and contamination.

5. Reactor shape and gas introductions must provide laminar flow conditions at the substrate. Gas introduction should be at the top of the reactor. Laminar flow is required to ensure deposition uniformity, maximize the efficiency of radical formation, and minimize precursor use and cycle times.

6. It is preferred that the internal surfaces of the reactor be appropriately treated to enhance coating adhesion on the sample surface and to make reactor cleaning more efficient and effective. This can include a method of minimizing precursor interactions with the chamber sidewalls and ports, and focusing the precursors at the substrate, such as an inert gas shroud.

7. Reactor shall be equipped with a heated chuck that is able to accommodate sample sizes ranging from chips of a few mm extent to 150 mm diameter substrates, and be designed to promote laminar flow patterns (1e). The reactor should be able to process these substrate sizes without any changes to the load lock or process chamber.

Furthermore, the 150 mm substrate heater must operate at ambient up to > 450oC with ≤ ± 5% non-uniformity and work independently from the reactor chamber, lid, and exhaust heating.

8. Sample loading shall be consistent with automatic load lock operation. Sample holder and transfer mechanism must be able to load into the ALD chamber under viscous laminar flow conditions. The sample entry port shall be gate-valved. The sample

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entry port should be designed to prohibit any deposition on or near the gate-valve, o-rings, or operating mechanism to ensure reasonable operating life. The gate-valve shield design, such as an inert gas shroud, should block any deposition or particles from getting into the gate-valve and sample loading areas and provide a clean transfer.

9. The reactor design shall be completely modular to allow for system modifications and upgrades including ozone integration, replacement chamber, addition of in situ diagnostic ports, and/or addition of transfer systems to incorporate into a cluster tool.

B. GAS DELIVERY SYSTEM

1. The system shall separate the precursors and co-reactants before injection into the chamber using at least 4 individual reactor inputs (“Positions”) that feed into the reactor. Once introduced into the reactor, the precursors must be uniformly distributed across the substrate for uniform deposition.

i. At least one Position shall be a single vapor delivery source for high vapor pressure liquids/solids. This source shall:

(a) Be able to accommodate at least one 50 cubic centimeter ampule.

(b) Must be modular to accommodate future upgrades to the number of precursor sources

ii. At least two Positions shall be flow-through vapor delivery sources for low vapor pressure liquids or solids.

(a) The flow through sources will have the ability to charge the bubbler with inert gas or use a software controlled bypass valve allowing the cylinder to behave as a vapor draw system.

iii. At least one Position shall be a multi-source vapor delivery source for moderate to high vapor pressure liquids/solids. This source shall:

(a) Be able to accommodate at least five ampoules, each with 50 cubic centimeter capacity, connected in parallel.

(b) Have an independent input line for a carrier gas.

(c) Have at least seven independently controlled heater zones (one at the input line, one at the valve, and one for each source ampoule) up to 250oC with less than 6% heater non-uniformity per zone.

2. The system shall contain at least 8 precursor injection points for metalorganic and co-reactant precursors with the ability to upgrade to at least 12 precursor injection points.

Each delivery source will have a minimum of three independent heater zones and be independently controlled up to 200oC with ± 6% uniformity or better. Each of the precursor delivery lines (Positions) must be equipped for uniform heating, preferably by cladding with fit for purpose thermal reservoir blocks and heating with resistive heating tapes and insulating jackets around this cladding/ thermal reservoir. Heated surfaces should be insulated for efficient and stable operation. All parts of each gas delivery line from the precursor bubbler to the entry port into the reactor should be

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heated in the described manner and up to 200oC or higher with ± 6% uniformity or better.

3. Each source shall include a fast actuating ALD valve capable of operation at 200oC with an actuation speed of 18 x 10-3 seconds or less. The valve control signal shall have a resolution of below 20 microseconds. Constant purging of ALD valves shall be enabled to ensure cleanliness and reasonable operating life, and preferably use a 3-port design.

4. For the purpose of transporting metalorganic precursors and co-reactants to the reactor, each input line shall have independent carrier gas flow and will be regulated by a mass flow controller (0-180 standard cubic centimeters per minute or more) of the serial control interface and metal sealed variety. Each mass flow controller shall be compatible with argon or nitrogen gases and equipped with an isolation valve.

5. The system shall include a plasma source, preferably an Inductively Coupled Plasma (ICP) plasma source (See 3. Plasma Source) that can be used for plasma-enhanced

ALD.

i. This source shall include at least four plasma gas lines and must be expandable to up to 6 or more plasma gas lines. Each line shall be constructed of materials and fittings compatible with the use of hydrogen, oxygen, argon, nitrogen, and ammonia.

ii. Each plasma gas source line flow shall be metered by mass flow controllers (0-180 standard cubic centimeters per minute or more) of the serial control interface and metal sealed variety with both upstream and downstream isolation valves with indicator switches.

iii. System shall include safety features to prevent mixing of incompatible gases, (such as hydrogen and oxygen), such as a gas compatibility programmable logic controller (PLC).

iv. Ability to include at a later time an ozone source that delivers ozone through the plasma source when enabled.

6. All precursor sources (metalorganic or gas) shall be housed in a vented gas cabinet integrated onto the system enclosure that permits the mounting of up to two additional gas sources and their attendant mass flow controllers.

7. All integral fittings of the precursor delivery system (required and optional) shall be of the metal-sealed type.

C. PLASMA SOURCE

1. System shall be equipped with a remote plasma source such as an inductively coupled high-density plasma (ICP) source mounted at the top of the reactor, above the sample chuck.

2. The plasma source shall be capable of pulsed operation with less than 1 sec on/off time.

3. The plasma source shall come complete with a differentially pumped remote plasma source, RF power supply (50-1000W) operating at 13.56 MHz frequency, automated

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matching network, and suitable software interfacing to allow control through the system operational control system (see below).

4. Continuous operation (i.e. not pulsed) of the plasma can lead to undesired charge incorporation into the deposited films. For reasons already explained, mechanical shuttering must not be included in the chamber operation. Therefore, the plasma source shall be operated WITHOUT the aid of a shutter during processing and pulsing of the plasma activated precursor species must be accomplished through pulse operation of the plasma source itself.

5. The plasma source shall be fed gases from at least 4 gas lines with expandability up to a total of 6 gas lines (see section 2).

D. PUMPING SYSTEM

The system shall be a vacuum system with a base pressure of 20 mTorr or less. The vacuum system shall use only oil-free, dry pumps. The vacuum system shall include foreline purge/vent protection and optional foreline throttle valve.

E. REACTOR ENCLOSURE

1. The entire reactor shall be enclosed in a housing with removable panels for easy access and maintenance. The housing must act as a primary barrier to leaks where all doors are to be sealed and no external gas cabinets are required.

2. Due to space constraints, the system including the enclosure (but excluding the control computer console) shall fit within 100” length, 40” width, and 84” height.

3. The enclosure must contain ports for connections to an existing NRL fan/duct system.

IV. LOAD LOCK TRANSFER SYSTEM SPECIFICATIONS

The Load Lock transfer system shall, A. Contain a single wafer vacuum load lock system with a base pressure of 8.0 x 10-7 Torr or less. This load lock shall: a. Have a vacuum system containing a turbomolecular and/or molecular drag pump that is backed by an oil-free, dry scroll pump.

B. Have a VAT valve high vacuum valve between the load lock and ALD chamber.

C. Have an isolation valve for the turbomolecular and/or molecular drag pump to allow fast pump down and venting of the chamber.

D. Have appropriate gauges to measure the pressure.

E. Be able to automatically transfer substrates from the load lock to the ALD chamber.

F. Have the ability to load 150 mm SEMI spec wafers into the ALD chamber.

G. Have the ability to load substrates from chips to 125 mm SEMI spec wafers with the use of adaptors.

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H. Have the ability to load under viscous laminar flow conditions that establish a diffusion barrier and prevents any back streaming of any reactor byproducts.

I. Have a port for connection of vacuum diagnostic equipment.

J. Load Lock must be a module design, allowing for easy install and removal from ALD module

K. The load lock must have ability to land on wheels for easy transport and have the capability to level to ALD module.

V. INTEGRATED IN-SITU, DEEP-UV TO NEAR IR ELLIPSOMETER

SPECIFICATIONS

A. The system shall include a means of evaluating the thickness and composition of a stack of films, preferably an integrated in-situ multi-wavelength ellipsometer ranging from the deep-UV to the near IR (193-1690 nm) with a continuously rotating compensator ellipsometer (RCE) design and high speed parallel CCD detector to simultaneously collect the entire spectrum.

B. The ellipsometer shall be able to provide proof of thickness repeatability of ≤ 0.003 nm, for example measuring a calibrated SiO2 film at a fixed angle and ten second averaging with a fixed sample position.

C. The ellipsometer shall have the ability to perform true real-time measurements of the ellipsometric parameters psi, delta and %Depolarization with sub-monolayer sensitivity on the sample during the ALD process. This integration will provide a unique capability of the system to allow for end-point process control once a particular value of interest (thickness, optical constants, etc.) is reached.

D. The ellipsometer shall be attached to the main ALD system chamber with a fixed takeoff angle between 65o and 75o.

E. The chamber ellipsometer ports cannot use mechanical isolation devices to protect port windows from unwanted film deposition. The use of shutters can lead to undesired flow disruptions, as well as the formation of particulates that can negatively impact the process. Therefore, a method of minimizing precursor interactions with the ellipsometer ports, such as gas shrouding or purging, needs to be incorporated into the ALD chamber design, as discussed in section 1b of the ALD reactor specifications.

VI. OPERATIONAL CONTROL

A. The ALD reactor shall be computer controlled via an electronic control unit that is also interfaced to a Windows-10 based or similar computer system with the following properties:

1. PC-based current generation computer system with

i. A hard disk memory storage of at least 500 Gbytes,

ii. System memory of at least 8 Gbytes,

iii. One monitor of 21-inch or larger diagonal, flat panel preferred.

iv. Ethernet interface to ALD control electronics.

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2. Running on the computer system will be a custom designed, dedicated software package for control and monitoring the process,

i. The software shall provide a graphical user interface (GUI) for reactor control and monitoring.

ii. Software should support multiple user accounts and passwords with different levels of access such as user, process engineer, maintenance/technical/service, and operator.

iii. The software shall allow development of processes and come with example processes for growing films by thermal ALD and plasma enhanced ALD (PEALD). Furthermore, the software should be able to load and save user developed recipes.

iv. The software shall permit control of each aspect of the process in either manual or recipe (automatic) modes of operation.

v. The software shall provide precursor heating control in order to prevent thermal decomposition of the precursors.

vi. The software shall allow separate control of the full range of each variable of the growth process, including, substrate temperature, precursor temperature, gas mass flows, gas delivery selection through valve actuation, pulse time (0.010 to 1 second), plasma source conditions, etc.

vii. The software should provide simultaneous standard chart recording of ≥ 10 different process signals, including chamber pressure and temperature, substrate temperature, precursor temperature, plasma source conditions, etc.

viii. The software shall provide a real-time plotting of precursor pulses during growth with < 15 Hz resolution or better.

ix. The software shall provide real-time ellipsometer feedback during film processing where certain signals such as thickness can be charted. It would be desirable for the software to be programmable for end-point process control to allow the ellipsometer output to trigger a stoppage in growth when a particular target parameter value is reached.

x. The software shall provide automatic data logging of login/logout events, recipes executed, process variables, ellipsometric feedback, system warnings, alarms, and status messages.

xi. The software shall be capable of dynamic process adjustment and emergency shutdown in the event of any process parameter moving out of a predefined window.

xii. Also integral to the software will be safety monitoring that will be capable of triggering a safety shutdown when there is a major system failure.

3. The software should be flexible for new operations and upgrades as additional functionalities are added free of charge.

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4. The Contractor shall supply a set of parameters and processes that will run on the dedicated software program for performing the deposition of aluminum oxide (Al2O3), hafnium oxide (HfO2), zinc oxide (ZnO), titanium dioxide (TiO2), titanium nitride (TiN), and aluminum nitride (AlN) thin films.

B. The control system shall include

1. appropriate interlocks to ensure that the tool is safely operated.

2. an ozone sensor and appropriate interlocks to the tool.

3. the ability to prevent the unwanted mixing of precursors. For example: limiting the explosive combination of H2 and O2 and limiting undesirable cross contamination of precursors.

C. The ellipsometer also shall be computer controlled via an electronic control unit that is interfaced to an independent Windows-10 based or equivalent computer system, separate from the ALD reactor computer.

1. Running on the ellipsometer computer system will be a custom designed, dedicated software package for control and process monitoring.

i. The software shall provide a graphical user interface (GUI) for data acquisition, data analysis, optical simulations, and routine calibrations.

ii. The software will allow for complete analysis of the thin films and provide a database of optical parameters and models associated with a variety of commonly known materials.

iii. Software should support multiple user accounts and passwords.

2. Furthermore, the ellipsometer shall be able to interface with the main ALD system’s operating software allowing for data acquisition and end-point control.

VII. DOCUMENTATION:

Also included upon delivery is at least one complete document set (printed and electronic) written in the English language containing, operating manual, service manual, sub-suppliers manuals of the various subsystems components, list of components, flowcharts, wiring diagrams, list of interlocks, factory settings, safety system overview, details on obtaining on-line or telephone assistance, and a spare parts list.

VIII. SAFETY

The ALD reactor shall have a safety system that addresses each of the following requirements:

A. Continuous monitoring of electronic control unit and its onboard microprocessors. In case of failure or malfunction, system shall shut down all heaters and the RF power to the plasma, set all flows to zero and close all valves.

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B. Continuous monitoring of control software communications. In case of failure or malfunction, system shall shut down all heaters and the RF power to the plasma source, set all flows to zero and close all valves.

C. An emergency main power off circuit shall be provided that can be manually or automatically activated.

D. Process control software and associated control electronics shall prevent operation that could damage the equipment or create a hazard as related to vacuum, heating, cooling, and other hardware interlocks including those for the plasma source.

E. All heater sources shall operate with an adjustable power limit to prevent overheating of components.

F. All hot zones shall be insulated and labeled with safety warnings.

G. Safety interlocks required (minimum):

1. Process interlock for vacuum pressure, by which a process cannot start unless pressure is < 1Torr.

2. Process interlock with thermal monitor. If any temperature monitor is not producing a signal, process cannot be started.

3. Use of a gas compatibility programmable logic controller (PLC) to prevent mixing of incompatible gases, such as hydrogen and oxygen.

4. Additional interlocks available for future upgrades – load lock, turbomolecular pump, and other energetic sources (other than primary plasma source).

H. System shall provide up to two emergency main power off buttons.

I. Each alarm will be announced by visual signal identifying the alarm on the process display monitor and logged into the data logging portion of the dedicated ALD system operating software.

IX. INSTALLATION

The installation of the system shall be performed by engineers supplied by the Contractor. NRL shall be responsible for providing the Contractor with access to the space where the tool will reside, all of the required facility utilities, which include power, ventilation, and cooling water supplies that will be prepared to the Contractor’s specification. NRL will provide all of the required gas sources and these will be in-place as per the Contractor’s specifications.

A. In order to facilitate this, at the time of the contract award, the Contractor shall provide NRL with all the facility’s requirements that are necessary so that all of the required utilities will be in-place prior to the time of the installation.

B. The Contractor must provide personnel who will install the tool into the NRL facility.

The Contractor shall inform NRL at the time of award of material and personnel requirements for the installation process. The Contractor will also oversee the unpacking of the tool, positioning, and subsequent installation. The Contractor shall be responsible for ensuring that safety procedures are followed during this process.

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C. Upon completion of the physical installation, the Contractor supplied personnel shall ensure that all components of the system are properly operating. They will then proceed to ensure that all of the specifications are met as detailed under Performance Requirements within 60 days of completion of physical installation.

X. TRAINING

A. The Contactor shall provide training for NRL personnel on the use, maintenance and basic repair procedures for the reactor and load lock. Information will be provided regarding the various components of the reactor system and their function. As part of the training NRL personnel will be taught how to grow Al2O3, HfO2 and AlN thin films. This training will include all of the procedures including wafer preparation, wafer insertion into the system, bringing the system up to operating temperatures, performing the growth and subsequent system cool down, venting and wafer removal. This training shall be performed under the supervision of Contractor supplied personnel. This training should be done in a single stage and coordinated with installation at NRL and be for a period of at least three days.

B. The training shall include both the hardware and software aspects of the system. NRL personnel will be shown how to configure a growth run, shown which sensor readings are key to a good run, how to interpret the variations in sensor readings and when to stop a run.

C. The Contractor shall provide training for NRL personnel through a Sub-contractor on the use, maintenance and basic repair procedures for the in-situ ellipsometer separately from the installation of the ALD. Information will be provided regarding the various components of the ellipsometer and their function. As part of the training NRL personnel will be taught how to focus the light source to maximize signal intensity on samples located within the ALD reactor chamber, how to replace light sources, and basic analysis of ellipsometric parameters psi and delta. The on-site training should be done in a single stage and be for a period of at least one day. The Contractor should include registration in an off-site classroom type training that covers the basics of ellipsometry modeling and data analysis for a period of three days.

D. The training program will be for a minimum of two (2) and as many as five (5) NRL personnel.

XI. WARRANTY

A warranty customary to the Contractor’s policies is preferred if offered. The Contractor shall register all equipment requiring warranty by other manufacturers; such warranties shall be effective from the date of system acceptance. The warranty terms and options must be included in the system price.