ALD-ALE_Reactor_specifications.doc

Procurement of reactor for atomic layer deposition of oxides, metals and semiconductors

Code 6880

Background

The Power Electronics Branch of the Electronics Science and Technology Division is already involved in developing low temperature growth of ultrathin oxides, metals and semiconductors. These materials are of interest to the US Navy since they can serve as high quality gate dielectrics for rf and power switches, protective and/or functional coatings for thermal space management, chaff and underwater sensors, and as active layers modulating IR sources. These devices promise improved performance in future communications, thermal management, battlespace awareness, radar and power management systems. This procurement is directed to obtaining an advanced atomic layer deposition/ epitaxy reactor that will enable Branch personnel to continue to perform research and development in the growth of desired thin film structures with those properties that are envisioned for the target electronic and optoelectronic devices. The equipment will be housed in a laboratory in Bldg 208, Rm. 124A.

General Specifications

The reactor consists of a single hot-walled reaction chamber that is serviced by gas handling, vacuum, and DC heating systems, and is capable of operating in traditional atomic layer deposition (ALD), plasma-assisted ALD, radical-enhanced ALD, atomic layer epitaxy (ALE), plasma-assisted ALE and radical-enhanced ALE modes. Further, for the ALD modes of operation, the system should be able to operate in a “static” mode that isolates the reactor from gas inlet and pumping after precursor injection to permit coating of high aspect ratio surface topologies. Additionally, the reactor should be able to go to high temperatures to enable epitaxial growth of films. The reactor should have a load lock designed to automatically transfer wafers without introducing atmospheric contaminates to the growth chamber. Additionally, the reactor should have in situ diagnostic ports for real-time structural and chemical analysis of deposited films. The reactor should have at least 6 precursor ports and at least 4 gas lines with the ability to upgrade to additional gases in the future as required. In general, the reactor should be modular so that they system can be upgraded in the future for additional sources, pumps, and diagnostic ports. The process should be computer controlled and the reactor should have an integral safety system. Finally, the system should be able to be delivered within a 12 week timeframe.

Detailed Reactor Specifications

1. Reactor chamber

a. Reactor chamber must be constructed of stainless steel consistent with commercial high vacuum processes. It is preferred that the internal surfaces of the reactor be appropriately treated to enhance coating adhesion and to make reactor cleaning more efficient and effective. It is preferred to have a single chamber reactor that allows for faster heating of samples and straightforward in situ realtime analysis of deposition (via ellipsometry, QCM, etc.). There should be at least two ports with ideal take-off angles for ellipsometry measurements and one wafer level port for additional diagnostics.

b. 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 300°C must be possible. The temperature should be programmable through operational control software and controlled with a proportional-integral-derivative (PID) control algorithm.

c. Reactor shape and gas introductions must provide laminar flow conditions at the substrate. Gas introduction should be to the top of the reactor. Documentation to verify laminar flow conditions at the substrate should be provided by the offerer. Laminar flow is required to ensure deposition uniformity and radical efficiency maximization and minimal precursor use and cycle times.

d. Reactor must be equipped with a heated chuck able to accommodate up to 100mm diameter substrates and be designed to promote laminar flow patterns (1c). As in (1c), documentation to support that the design meets laminar flow conditions should be provided by the offerer.

e. Reactor design should be modular and allow for system modification including change in plasma, ion, or radical source mounted at top of reactor (see 3.a.), addition of load lock (entry port should be isolated from the growth chamber with a gate valve), integration with a glove box, change in pump type (dry or turbomolecular), replacement of chamber and/or addition of in situ diagnostic porting.

f. Sample insertion mechanism consistent with automatic load-lock operation. Sample holder and transfer mechanism must be consistent with the overall laminar flow requirements outlined above (1c). Sample entry port should be gate valved. Sample entry port should be designed to prohibit any deposition on or near gate valve o-rings or operating mechanism to ensure reasonable operating life. It is preferred that the gate valve shield design blocks any deposition or particles from getting into the gate valve and sample load areas.

g. The sample temperature must be able to achieve 800°C over at least a 4” diameter area in the center of the sample holder to allow for atomic layer epitaxy. Temperature should be measured and actively controlled by the operational control software using a PID control algorithm. Temperature must be controlled within 5 degrees of setpoint. This should result in a thickness uniformity of thermal and plasma Al2O3 films of 1.5%.

h. The reactor should be equipped with a load lock that has an automatic sample transfer. The load lock should be pumped with a minimum 150 liter/second magnetically levitated turbomolecular pump.

2. Gas delivery system

a. Six precursor cylinders must be provided of volume equal to or greater than 50 cubic centimeters. Each bubbler should incorporate a manual isolation valve and employ metal seals.

b. System must come with 6 heated precursor lines for metalorganic precursors. Each line shall be capable of being heated up to 200°C. Heating shall be accomplished with resistive heat tapes and jackets and heated surfaces should be insulated for efficient, 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 200°C.

c. Each line must include a fast acting ALD valve capable of operation at 200°C and with actuation speed of 15 x 10-3 seconds or less. ALD valves shall be constantly purged to ensure cleanliness and reasonable operating life.

d. Each line must also include a high temperature manual shut off valve to permit changing of precursor bubblers.

e. System should include two low vapor pressure delivery cylinders with nitrogen to enhance transport of select low vapor pressure metalorganics..

f. For the purposes of transporting metalorganic precursors to the reactor, a single mass flow controller (0-200 standard cubic centimeters per minute or more) must be provided and configured to carry the vapor from each heated precursor line. The mass flow controller must compatible with argon or nitrogen gases.

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

h. System should be expandable to up to a total of 6 plasma gas lines. Each line shall be constructed of materials and connections compatible with the use of hydrogen, oxygen, argon, nitrogen, ammonia and hydrazine.

i. 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 2 mass flow controllers, etc.

j. Each 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.

k. System should be equipped with an ozone generator with lines that are separate from gas lines to the plasma source and compatible with UHP oxygen and a separate exhaust line.

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

m. Appropriate porting for compressed air to operate pneumatic valves must be provided.

3. Plasma Source

a. Systems must come equipped with an inductively coupled high-density plasma (ICP) source mounted at the top of the reactor.

b. The ICP source must be capable of pulsed operation with less than 1 x 10-3 second on/off time.

c. The ICP source must come complete with a plasma source, automated tuner or matching network, RF power supply (400-700W) and suitable software interfacing to allow control through the system operational control system (see below).

d. The ICP source must be operated WITHOUT the aid of a shutter during processing as pulsing of plasma activated precursor species shall be accomplished through pulsed operation of the plasma source itself. Shutter operation would lead to undesired flow disruptions that can result in non-laminar flow and have a negative impact on the process. Unshuttered, continuous operation can lead to undesired charge incorporation into the deposited film.

e. To reduce maintenance concerns and ensure stable performance of the ICP source, a constant flow of inert gas must be conducted through the source at all times during operation.

f. The ICP source shall be fed gases from 4 gas 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, ammonia and hydrazine.

g. The plasma source will be cooled with chilled water with at least 0.4 liter per minute.

4. Pumping system

a. The system shall provide porting for a dry process vacuum pump (>50 cubic feet per minute at 100 mTorr pressure) or alternatively a turbomolecular pump of up to 300 standard liters per minute. Adequate space shall be provided inside the system cabinet for a commercial dry pump with a pumping speed of 50 CFM or greater.

b. The system shall provide, at the porting point, a heated integrated vapor trap that operates up to 200°C and has surfaces that have been treated to enhance coating adhesion. The primary purpose of the trap is to keep non-volatile reaction products out of the dry pump and prolong its operating lifetime. The trap should be capable of removal and re-installation to permit routine cleaning or regeneration.

c. The system must incorporate an integrated pump line valve to allow long exposure times of a precursor pulse permitting the coating of high aspect ratio surface structures.

d. The system must also come equipped with appropriately ranged vacuum gauges for process monitoring and control.

e. The reactor should be equipped with an appropriate dry process pump with pumping speed greater than 50 CFM at 100 mTorr pressure.

f. The reactor should be equipped with a 300 standard liters per minute magnetically levitated turbomolecular pump.

g. SEPARATELY PRICED OPTION: The reactor should be equipped with a throttle valve in front of the pump port and an associated valve controller and software interface to the controller.

5. Reactor enclosure: The entire reactor is to be enclosed in steel and/or polycarbonate housing that acts as a primary barrier to leaks similar to standard gas cylinder storage cabinets; all doors are sealed to prevent leaks to the outside.

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

b. 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.

Operational Control

1. The reactor is computer controlled via an electronic control unit that is also interfaced to a Windows-based computer system; the computer system will have the following properties:

a. PC-based current generation computer system with

i. a hard disk memory storage of at least 100 Gbytes,

ii. system memory of at least 512 Mbytes,

iii. monitor of 15-inch or larger diagonal, flat panel preferred.

iv. USB interface to ALD control electronics

v. preferably running at least Windows 7

vi. SEPARATELY PRICED OPTION: The computer system will be provided with an uninterruptible power supply that will protect the computer and send a signal to the reactor that will ensure proper system shutdown in the event of power failure

b. 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 for reactor control and monitoring.

ii. The software must allow development of processes and come with example processes for growing films by ALD, PA-ALD, ALE and PA-ALE. The software should be able to load and save user developed recipes as well.

iii. It is preferred that the software provide automatic data logging of process variables.

iv. This software must allow separate control of the full range of each variable of the growth process, including, substrate temperature (room temperature to 800°C), precursor temperature (room temperature to 200°C), 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 times (0.015 to 1 second), plasma source conditions, etc.

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

vi. The software must also provide a real-time plotting of precursor pulses during growth.

vii. 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.

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

c. The Contractor 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 oxide (HfO2), hafnium nitride (Hf3N4), and platinum (Pt) thin films.

Documentation:

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

Safety

1. The reactor must have a safety system that addresses each 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 ICP plasma, set all flows to zero and close all valves.

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 ICP 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 ICP 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)

i. Process interlock with vacuum pressure. Cannot start a process unless pressure is < 1 Torr.

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

iii. The plasma source shall be interlocked with the cabinet exhaust pressure (to avoid build-up of ozone). If cabinet exhaust is inadequate, plasma source will not operate.

iv. Hydrogen and oxygen mass flow control valves are interlocked to not permit them to be operated at the same time.

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

h. Offerer shall provide up to three emergency main power off buttons with one capable of being remotely located.

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

Installation

The system should be delivered within 12 weeks after the purchase order is accepted. The installation of the tool 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 also provide all of the required metalorganic and gas sources and these will be in-place as per the Contractor’s specifications.

1. 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.

2. 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 and subsequent installation. The Contractor shall be responsible for ensuring that safety procedures are followed during this process.

3. 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.

Training

The Contractor 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, Hf3N4, and Pt thin films. This training will include all of the procedures including wafer preparation, insertion in to 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 done under the supervision of Contractor supplied personnel. The training should be done in a single stage and coordinated with installation at the NRL and be for a period of at least two days.

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.

The training program will be for 3 NRL personnel.

Performance Requirements

1. The Contractor must be able to document the successful manufacture, installation, and operation of an atomic layer deposition/epitaxy reactor of the type described in the General and Detailed Specifications for the growth of Al2O3, HfO2, Hf3N4, and Pt.

2. The Contractor must demonstrate the following after installation at NRL:

a. No leaks in the reactor tubing and seals as detected by a calibrated helium leak detector (supplied by NRL) down to 2 x 10-8 mbar-l/s;

b. Base pressure in the range of 10-2 mbar;

c. Process gas flows stable within ± 2% at process related flows, for a period of two hours;

d. Susceptor temperature 800°C ±5°C with a nitrogen flow of approx. 20 standard centimeters per minute for a period of two hours.

3. In addition, the Contractor shall demonstrate the performance of the reactor by growing the following layers 1000Å thick:

a. Al2O3 with refractive index > 1.60

b. HfO2 with refractive index > 2.0

c. Hf3N4 with refractive index > 2.3

d. Pt with resistivity of < 100 -cm

4. NRL will provide acceptance testing of said films through a combination of ellipsometry, electrical resistivity and atomic force microscopy step-profilometry measurements.

5. The Contractor shall provide a Certificate of Compliance guaranteeing that all the requirements of this specification have been met.

Warranty

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 Contractor shall register all equipment requiring separate 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.