ALD Specifications.pdf

Specifications for Atomic Layer Deposition (ALD) Reactor

General Requirements

1.1 Scope. The Naval Research Laboratory of Washington, DC (NRL-DC) is acquiring an atomic layer deposition (ALD) reactor system for growth of thin films atop various substrates.

The document describes the minimum technical requirements and minimum acceptable performance standards for the system. Atomic layer deposition is implemented as a vapor transport of precursor materials from source containers to samples mounted on a temperature-controlled stage. Adhesion of the vapor to the sample surface occurs with 1 molecule thickness, and temperature and/or plasma processes convert the adsorbed carrier molecule to the final film product with residual carrier components pumped away, followed by a new cycle of vapor injection, deposition, reaction and pumping that is repeated until desired film thickness is achieved. The tool will be placed in a multiple user facility and must provide ease of operation and safety to those in the facility. It must be capable of uniform deposition on various sized substrates and wafers of 150 mm DIA or greater. The reactor must implement gas diffusion barrier design to keep particulates away from the sample loading area, to focus the precursor at the sample surface, and to eliminate the need of internal mechanically actuated components. The reactor should accommodate a minimum of 8 precursor sources with the ability to upgrade to 12 precursor sources and configured with 4 (minimum) process gas lines. The reactor should have optical view ports and mounts for use of an NRL-provided ellipsometer for real-time analysis of deposited films. Furthermore, the ALD reactor and the ellipsometer should be computer controlled from a single workstation and the reactor should have an integral safety interlock system.

1.2 Installation Site. The vendor shall install the tool at Naval Research Laboratory, Washington DC 20375, Building 250 in a Class 100 clean room at a location to be designated by the Contracting Officer's Representative (COR). The vendor shall install the tool in a manner consistent with typical clean-room operating procedures. The tool is to be compatible with provided utilities: 208 VAC, single and 3-phase electrical power, 110 VAC electrical power, < 80 psi compressed air, process chilled water, and liquid and dry gas nitrogen supply. The main system pump will be located in the north side utility spine having a distance approximately 25 feet from the ALD tool.

1.3 Description and Primary Tool Components. The reactor will consist of a single hot-walled, viscous flow reaction chamber configured with gas handling, vacuum, substrate electric bias (option), and DC heating components, and is capable of operating in both traditional thermal ALD and plasma enhanced-ALD (PE-ALD) modes. An automatic load-lock transfer

ALD REACTOR SPECIFICATIONS Page 1 of 12 system is required to deliver samples in and out of the process chamber without venting and without introducing contaminates into the growth chamber.

1.4 All responders are required to tabulate their responses to all enumerated requirements in this document with either “Meets requirement” or “Does not meet requirement.”

Failure to provide the information is cause for disqualification.

1.5 Items listed as Option will be obtained if funding is available.

Detailed ALD Reactor Requirements

2. ALD Reactor Chamber

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

2.2 The chamber can not use mechanical actuators within the chamber to prevent knock-off contamination of particles on surfaces/ports within the chamber where deposition is not intended. Particulates from the actuators can contaminate the resulting films and disrupt gas flow within the chamber and mechanical motion can cause turbulent gas flow within the chamber leading to non-ideal growth conditions.

2.3 Two optical ports on opposite side walls are required to support in situ ellipsometry measurements. Each port will have identical take-off angles between 65o – 75o as measured from the normal axis of the substrate and located to allow the light source to reflect off the center of the sample to the detector mounted on the opposite side. The ports must have gas diffusion barriers to prevent deposition to the port windows during the ALD process while allowing continuous in situ measurements.

2.4 The reactor chamber must be heated to achieve hot wall operation. The heating should be resistive and include an insulating jacket. Reactor wall temperatures up to 250oC, minimum, are required. The temperature must be programmable through operational control software and controlled with a proportional-integral-derivative (PID) control algorithm. The reactor lid and precursor inputs should be fully clad with aluminum blocks or insulating jackets to maintain heating uniformity variations chamber, lid, and exhaust must be actively heated independently in order to create a thermal gradient that avoids cold spots within the system that may cause condensation and contamination.

2.5 Reactor shape and gas introductions must provide laminar flow conditions at the substrate during normal growth process conditions. Gas introduction should be at the top

ALD REACTOR SPECIFICATIONS Page 2 of 12 of the reactor and flow radially about the sample mounting plate. Documentation to verify laminar flow conditions at the substrate should be provided by the offerer. Laminar flow is required to ensure deposition uniformity and to maximize the efficiency of precursor gas for each deposition cycle, allowing minimal precursor use and cycle times.

2.6 Inert gas shrouding is the preferred technology to prevent reactants from contaminating non-sample surfaces and windows and for guiding precursor reactants to the substrate.

2.7 Reactor must be equipped with a heated chuck that is able to accommodate sample sizes ranging from mm-sized chips up to at least 150 mm diameter substrates and be designed to promote laminar flow patterns. The reactor must be able to process these substrate sizes without any changes to the load lock or process chamber. Furthermore, the substrate heater must operate between ambient to > 450oC with less than -uniformity or better and work independently from the reactor chamber, lid, and exhaust heating.

2.8 Sample loading will be via 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 and gas flow system should be designed to prohibit deposition on or near the entry valve that will reduce the risk of particles contaminating seals that may cause vacuum leaks.

3. Gas Delivery System

3.1 The system must separate the precursors and co-reactants using a minimum of 4 individual reactor inputs (referred to as Positions 1-4) that feed into the reactor through a top mounted radial showerhead and baffle design for uniform distribution.

3.1.1 Position 1: Single vapor delivery source for high vapor pressure liquids/solids. This source shall:

3.1.1.1 Be able to accommodate at least one 50 cubic centimeter ampule.

3.1.1.2 Have at least three independently controlled heater zones up to 250oC with less than

-uniformity per zone.

3.1.2 Position 2 & 3: Flow through vapor delivery source for low vapor pressure liquids/solids.

3.1.2.1 Precursor cylinders can be fully enclosed in an oven or heated with a minimum of 4 independent heater zones controlled up to 250oC.

3.1.2.2 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.

3.1.3 Position 4: Multi-source vapor delivery source for moderate to high vapor pressure liquids/solids. This source shall:

3.1.3.1 Be able to accommodate at least five 50 cubic centimeters ampoules connected in parallel.

3.1.3.2 Have an independent input line for an inert carrier gas.

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3.1.3.3 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 250o non-uniformity per zone.

3.2 The system must come with at least 8 heated precursor lines for metalorganic and co-reactant precursors with the ability to upgrade to at least 12 precursor lines. Each delivery line will have a minimum of three independent heater zones and be independently controlled up to 250oC or higher . Heating shall be accomplished with resistive heating tapes and insulating jackets. 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 heated in the described manner and up to 200oC .

3.3 Each source must include a fast-actuating ALD valve capable of operation at 200oC and with an actuation speed of 15 x 10-3 seconds or less. ALD valves shall be constantly purged to ensure cleanliness and long operating life.

3.4 For the purpose of transporting metalorganic precursors and co-reactants to the reactor, each input line will have an independent carrier gas flow and will be regulated by a mass flow controllers (0-200 standard cubic centimeters per minute or more) of the analog-type and metal sealed variety. Each mass flow controller will be compatible with argon or nitrogen gasses and equipped with an isolation valve.

3.5 The system must have an Inductively Coupled Plasma (ICP) plasma source that can be used for plasma-enhanced ALD. This source shall include:

3.5.1 Four plasma gas lines must be provided. Each line shall be constructed of materials and fittings compatible with the use of hydrogen, oxygen, argon, and nitrogen.

3.5.2 The system should be expandable to up to 6 or more plasma gas lines. Each line shall be constructed of materials and connections compatible with the use of hydrogen, oxygen, argon, and nitrogen.

3.5.3 Each plasma gas source line flow shall be metered by mass flow controllers (0-200 standard cubic centimeters per minute or more) of the analog-type and metal sealed variety with both upstream and downstream isolation valves with indicator switches.

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

3.5.5 Option. The system must allow for ozone source upgrade that delivers ozone through the ICP when enabled.

3.6 All precursor sources (metalorganic or gas) must be housed in an integrated, vented gas cabinet that permits the mounting of up to 2 additional gas sources and mass flow controllers.

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

3.8 Option. Gas purification assembly shall be incorporated to argon and nitrogen gas delivery lines to scrub for oxygen contamination. Units shall be sized according to gas flow requirements.

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3.9 Appr

provided.

4. Plasma Source

4.1 System must be equipped with an inductively coupled high-density plasma (ICP) source mounted at the top of the reactor.

4.2 The ICP source must be capable of pulsed operation with less than 1 sec on/off time.

4.3 The ICP source must come complete with a differentially pumped remote plasma source, RF power supply (50-1000W) operating at 13.56 MHz frequency, automated matching network, and suitable software interfacing to allow control through the system operational control system (see below).

4.4 The ICP source must be operated WITHOUT the aid of a shutter during processing as pulsing of the plasma activated precursor species shall be accomplished through pulse operation of the plasma source itself.

4.5 To reduce maintenance concerns and ensure stable performance of the ICP source during operation, a bypass channel can be used to ensure continuous flow of inert gas during operation.

4.6 The ICP source shall be accommodate 4 process gases lines with expandability up to a total of 6 gas lines, see section 2. Construction materials must be compatible with the use of oxygen, hydrogen, argon, nitrogen, and ammonia.

5. Pumping System

5.1 The system shall provide a quick connect configured port for a dry process vacuum pump

42 cubic feet per minute at 100 mTorr pressure) for easy removal from the system.

5.2 The reactor must be equipped with an appropriate oil-free, dry process pump with pumping speed greater than or equal to 45 CFM at 100 mTorr. The vacuum system should include a foreline purge/vent protection to safeguard the reactor from back streaming contaminants.

5.3 Option. The system must include a variable residence mode throttle valve that can operate in full static mode that isolates the reactor from gas inlet and pumping after precursor injection to permit coating of high aspect ratio surface topographies, as well as, a variable mode that provides a rapid change in sample surface temperature allowing for in situ rapid annealing of the growth film. The throttle valve must come with the associated valve controller and software interface to the controller.

5.4 The exhaust lines should be heated up to 200oC and incorporate high conductance foreline particle filtration to keep non-volatile reaction products out of the dry pump and prolong its operating life. The trap should be capable of removal and re-installation to permit routine cleaning or regeneration.

5.4.1 The exhaust trap will neutralize all reactive and precursor chemistries listed in this requirements document that have possibility of emanating from the process chamber.

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5.5 The system must be equipped with appropriately ranged vacuum gauges for process monitoring and control with individual gauges on the process chamber, exhaust lines, and load lock.

6. Reactor Enclosure

6.1 The entire reactor is to be enclosed in steel and/or polycarbonate housing with removable panels for easy access and maintenance. Housing acts as a primary barrier to leaks where all doors are to be sealed and no external gas cabinets are required.

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

6.3 The electronic controls for the reactor such as the programmable logic controller for the system control and interlock handling, DC supply, interface units, ground leakage protection, and safety devices are all appropriately housed in the reactor cabinet.

7. Load Lock Transfer System

7.1 The system must implement a single wafer vacuum load lock system that can reach a base pressure of 5 x 10-7 Torr in less than 5 minutes.

7.2 The load lock system should be equipped with a turbomolecular pump with a minimum pumping speed of 150 liter/second and backed by an oil-free, dry scroll pump. To meet the standardized vacuum pump criteria, the scroll pump must be able to pump to 5.0 mTorr or better.

7.3 The load lock will directly interface with the ALD reactor while using a high vacuum entry valve to isolate the ALD reactor chamber.

7.4 The system will have an automated sample transfer system using a linear rack and pinion transfer probe mounted directly to the load lock.

7.5 System will have the ability to load/unload samples into the ALD chamber under viscous laminar flow conditions that establish a diffusion barrier, thereby keeping particulates away from sample loading area.

7.6 The load lock must be configured with a port for attachment of a residual gas analyzer to be used primarily for determination of background gases and leak detection when not in processing mode.

7.7 (Option). The system must include a 0 – 200 AMU residual gas analyzer with interface and control software to the main system computer.

8. Computer and control system requirements.

8.1 The ALD reactor is to be computer controlled via an electronic control unit that is also interfaced to a Windows-11 or later based computer. The computer must have the following properties (minimum):

8.2 PC-based current generation computer system with

8.2.1 Memory storage of at least 500 GB.

8.2.2 System memory of at least 16 GB.

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8.2.3 Monitor(s) for GUI display and easy readability of process conditions.

8.3 The computer is to be configured with dedicated software package for control and monitoring the ALD system and process.

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

8.3.2 The software must support multiple user accounts and passwords with different levels of access such for operator (execution of process recipes), engineer (creation and execution of process recipes), and service (full system control).

8.3.3 The software must 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 at engineer level.

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

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

8.3.6 The software must allow separate control of the full range of each variable of the growth process, including, substrate temperature (room temperature to 500oC ), precursor temperature (room temperature to 200oC ), gas mass flows (0 to 200 sccm for plasma sources and 0 to 200 sccm for the metalorganic precursors), gas delivery selection through valve actuation, pulse time (0.010 to 1 second), plasma source conditions, etc.

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

8.3.8 The software must provide a real-time plotting of precursor pulses during growth with less than 15 μsec resolution or better.

8.3.9 Option. The software must be capable of interfacing to NRL-provided J. A. Woollam Co., Inc. M-2000 ellipsometer measurement system with a Model EC-400 interface controller, FLS-860 light source, and MQD Dual detector to provide real-time ellipsometric feedback of film optical properties and film thickness during the growth process. Preference is given for the ALD software to implement end-point-detection to automatically stop a growth sequence once a desired film thickness is achieved.

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

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

8.3.12 The ALD system control software must be capable to monitor safe operating conditions initiate shutdown if there is component or system failure.

8.4 The vendor must supply a set of parameters and processes that will run on the dedicated software program for performing the deposition of aluminum oxide (Al2O3), hafnium

ALD REACTOR SPECIFICATIONS Page 7 of 12 oxide (HfO2), silicon dioxide (SiO2), titanium dioxide (TiO2), titanium nitride (TiN), and aluminum nitride (AlN) thin films.

9. Documentation

9.1 The vendor will provide a minimum of one complete document set (printed and electronic) English language manuals including an operating manual, a 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.

10. Safety Requirements

10.1 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 ICP plasma, set all flows to zero and close all valves.

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

10.3 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 ICP source.

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

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

10.6 Safety interlocks required (minimum)

10.6.1 Process interlock with vacuum pressure. Cannot start a process unless pressure is <

1Torr

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

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

10.6.4 Additional interlocks available for future upgrades – load lock, turbomolecular pump, and other energetic sources (other than ICP).

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

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

11. Installation The installation of the system shall be performed by engineers supplied by the vendor.

NRL shall be responsible for providing the vendor with access to the space where the tool

ALD REACTOR SPECIFICATIONS Page 8 of 12 will reside, all of the required facility utilities that include power, ventilation, and cooling water supplies that will be prepared to the Vendor’s specification. NRL will provide all of the required process gas sources and these will be in-place as per the vendor’s specifications. (See Option xx below.)

11.1 The vendor shall provide NRL with complete facility requirements necessary to be in-place prior to the time of the installation.

11.2 The vendor will provide the qualified personnel to install the tool at the NRL facility.

Note NRL is considered a US military base and installation personnel must submit and be cleared using the form SECNAV 5512/1 to be allowed on base.

11.3 The vendor shall inform NRL at the time of award of material and personnel requirements for the installation process.

11.4 The vendor will also oversee the unpacking of the tool and subsequent installation. shall be responsible for ensuring that safety procedures are followed during this process.

11.5 Upon completion of the physical installation, the vendor-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.

12. Training

12.1 The vendor must provide training for NRL personnel on the use, maintenance and basic repair procedures for the reactor. 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 TiN thin films and TiO2 /SiO2 nanolaminate with supercycling . This training will include all of the procedures including wafer preparation, insertion into the system, bring 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 vendor 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.

12.2 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.

12.3 The training program will be for a minimum of 2 NRL personnel

13. Additional Options.

13.1 Option. The vendor shall be responsible for coordination and installation of orbitally welded process gas lines from gas bottle sources in the NRL-250 north side utility spine to the instrument location in the cleanroom, as shown in the figure below. The gases to be suppled are argon, nitrogen, hydrogen, and ammonia. NRL will provide process gas bottles.

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13.2 Option. The vendor will supply precursor materials compatible with the system for the deposition of aluminum oxide (Al2O3), hafnium oxide (HfO2), silicon dioxide (SiO2), titanium dioxide (TiO2), titanium nitride (TiN), and aluminum nitride (AlN) thin films.

13.3 Option. The vendor will provide spare parts for common wear components including replacement windows for sample viewing and ellipsometric measurements, o-rings, and refurbish kits for dry pumps.

14. Warranty

14.1 The system shall be provided with a 1-year factory warranty that covers all parts, labor and travel expenses for on-site support of the equipment. The warranty period shall begin on the date of system acceptance. In addition, the vendor shall register all equipment requiring warranty by other manufacturers; such warranties shall also be effective from the date of system acceptance. The warranty terms and options must be included in the system price.

ALD System

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Performance Requirements

1. The vendor must 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-enhanced deposited TiN and TiO2 /SiO2 nanolaminate.

2. The vendor must demonstrate at factory testing the following

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

b. Main chamber base pressure 2.0 x 10-2 Torr or less using 25 feet of exhaust tubing between chamber and main pump.

c. Substrate load lock base pressure less than 2.0 x 10-6 Torr within 10 minutes of startup from atmospheric pressure and less than 5.0 x 10-7 Torr within 1 hour of startup.

d. for a period of two hours

e. Substrate heater temperature great than 400oC 20 standard centimeters per minute for a period of two hours.

f. Delivery line temperatures and valve assemblies (Sources 1-4, chamber lid, MFCs, and isolation valves) temperature uniformity variation less than argon flow of approx. 20 standard centimeters per minute for a period of two hours.

3. In addition, the vendor shall demonstrate the performance of the reactor by growing the following layers on individual 150 mm DIA Si wafers (all with 10 mm edge exclusion zone):

a. Al2O3 greater than 100 nm 2 thickness variation using both thermal and plasma enhanced ALD. The index of refraction of these films shall be greater than 1.60 with uniformity variation less than at a wavelength of 633nm.

b. HfO2 greater than 50 nm using thermal ALD. The index of refracti wavelength of 633nm.

c. AlN greater than 50 nm thick film with less than uniformity variation using plasma enhanced ALD. The index of refraction of these films shall be greater than or equal to 1.92 with uniformity variation less than at a wavelength of 633nm. Films must contain l oxygen content.

d. Option. TiN with thickness greater than 50nm, with < + variation .

4. The vendor must 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.

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5. NRL will provide acceptance testing of said films through a combination of tools including ellipsometry, depth profiling x-ray photoelectric spectroscopy (XPS), secondary ion mass spectroscopy, x-ray reflectivity, and atomic force microscopy step-profilometry measurements.

6. The vendor shall provide factory testing and compliance results and a Certificate of Compliance guaranteeing that all the requirements of this specification have been met.

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