N00173-15-R-JM02_Deposition_System_Specifications.pdf

Deposition System Specifications

1. The Naval Research Laboratory (NRL) has a requirement for an ultra-high vacuum system to be used to clean semiconductor substrate surfaces in-situ and deposit a variety of pure metals including refractory metals, metal oxides, and metal nitrides via electron beam evaporation combined with exposure to gas atoms or ions. The major components include a plasma source of atoms or ions, an e-beam evaporator, a sample stage, and a load lock. All components are to be reliable and serviceable commercial parts with demonstrated field use and track record. Since the system is likely to be used for purposes not fully anticipated at this time, it should be built and documented in a way that allows future modification. The system must include the following features and components.

a. A system description. The system description must include:

Mechanical drawings of the system including all major components (eg frame, vacuum chamber, load lock, specimen holder, atom source, and e-beam hearth) with enough detail to show the components will function as required.

A list of standard components together with their manuals (or references to manuals) and/or other documents as may be required to demonstrate their functionality.

A description of the required utilities to be supplied by NRL including electric power connections.

A draft system description must be submitted no later than 30 days after the contract is finalized. The Government shall have up to 14 days for review and acceptance/rejection. The description must be approved before work starts.

Grounds for rejection may include insufficient detail or indications that the proposed hardware will not meet specification.

The description must be delivered in a standard electronic format.

b. A system manual. The system manual must include:

Descriptions of overall system operation including desirable and acceptable operating ranges for parameters such as temperature, pressure, power, cooling and gas flow.

Drawings and descriptions of the mechanical, electrical, pneumatic, and cooling systems with sufficient detail to troubleshoot and service the system as well as integrate additional components.

Descriptions of all software and electronic interfaces

Recommended maintenance procedures

A draft system manual must be submitted at least 14 days prior to installation.

The system manual must be approved prior to acceptance.

The manual must be delivered in a standard electronic format. If computer software is included with the system a copy of all software must be included with the manual.

c. A plasma source and electronics able to produce neutral atoms from molecular gases including hydrogen, oxygen, and nitrogen.

The atom flux must provide at least 1E15 atoms/cm2/s at the substrate. The vendor must supply data showing evidence of the atom flux and its stability over 60 minutes time.

If a matching network is required, it should operate automatically

One alumina tube must be provided. The discharge tube must be interchangeable between boron nitride, silica, and alumina.

The source must allow complete field-service including replacement of the discharge tubes and grids.

The source package must include these controls operated from a remote location: shutter, three gas shutoff valves, three mass flow controllers (including control electronics) covering appropriate flow ranges for each gas.

The source must be positioned to provide line of sight to the specimen.

The source must be configurable to operate as an ion source with adjustable ion energies; however the parts required for extracting ions should be proposed as an option.

d. An electron beam evaporation hearth

UHV compatible

Linear crucible tray containing 6 crucible pockets, each at least 7cc volume

Automated crucible indexing.

A remotely actuated shutter covering the source.

Both manual and automatic controls capable of operating the e-beam hearth at a controlled deposition rate, and opening and closing the sample shutter in order to deposit a pre-defined thickness.

Water-cooled shield blocking thermal radiation and stray metal flux

1. The shield must block the thermal radiation and evaporated flux as much as possible, such that the flux of heat and metal onto the chamber walls is reduced.

2. The shield must allow metal flux to the sample area and thickness monitor, and allow a view of the e-beam location on and near the crucible.

3. The shield must be easy to remove for service.

4. The hearth must be useable with or without the shield.

The hearth flange must be mounted in a way that allows easy user service including exchange of source crucibles, filament replacement, and service of the radiation shield.

The plumbing for the hearth and radiation shield must include a means of removing the coolant prior to system bake (eg blowing out the water line with compressed air or nitrogen).

The cooling water must be monitored with a flow switch and interlocked with the power supply

The system must include a means of visually observing the electron beam location on the source material, using a mirror or shutter and viewport such that source material is not normally deposited onto the viewport.

e. A power supply and control system for the e-beam hearth

5 kW switch mode power supply with variable high voltage 2-10 kV, separate high voltage output for glow discharge cleaning, 1 microsecond arc suppression, 5 millisecond arc recovery, able to withstand continuous arcing

Beam position and sweep controller with handset to control beam power and sweep while operator is observing the hearth through the chamber viewport

Filament power supply

Interfaced to thickness monitor for deposition rate control

Interlock for use with water flow and pressure sensors

f. An ultra-high vacuum (UHV) capable chamber and components

Leak tight to less than 1E-11 torr-liter/second.

Fabricated from 304 or 316 stainless steel

All parts must be compatible with baking at up to 200oC while under high vacuum.

The flanges must be standard CF “conflat” (aka DN) flanges and sealed with standard flat copper gaskets. Elastomer seals may be used if they are leak tight and bakable.

Large/heavy flanges expected to be opened frequently must be supported with an external mechanical system

One set of removable liners to facilitate cleaning

A viewport and chamber lamp providing a view of the specimen during transfer from the load lock.

A large port located in a position that allows manual access to the specimen stage.

A large port located in a position that allows manual access to the e-beam hearth.

At least 2 unused/blanked ports sized 2.75” od.

At least 2 unused/blanked ports sized 4.5” o.d. or larger, oriented for confocal deposition (on axes coincident with the center of the sample area when the source-sample distance is 350 mm).

g. A turbo-molecular vacuum pump for the main chamber

Pumping speed for hydrogen at least 500 liter/s.

Compression ratio for hydrogen at least 4E5.

Rotor shaft supported at both ends, using a magnetic bearing free of hydrocarbons on the UHV side.

Mounted horizontally or at an inverted angle to reduce chance of solids entering the pump

Water cooled

Integrated drive electronics

Mean time between failure greater than 20 years

h. A backing pump oil-free pumping speed greater than 10 m3/hr base pressure below 0.1 torr sound pressure level below 60 dB pump pure hydrogen field-serviceable equipped with an exhaust port silencer

i. An isolation valve between the turbo-molecular pump and chamber

Remote electronic actuation

The valve must close automatically in the event that the turbo-pump slows below a preset minimum.

j. A sample introduction load lock

A manual gate valve isolating the load lock from the main chamber

A manually operated access door with o-ring seal.

Magnetically coupled manual transfer rod

Total pressure gauge(s) reading from atmospheric pressure to below 1E-8 torr

Turbo pump with at least 60 l/s pumping speed and compression ratio for N2> 1E11

The turbo pump should be equipped with an oil-free backing pump with adequate pumping speed and sound pressure level below 60 dB. The same backing pump may be used for both the load lock and main chamber provided that plumbing and valves are supplied to switch between the main turbo and load lock turbo.

A vent valve with fitting for a ¼” gas supply tube.

k. A specimen stage

The stage must accept specimen carriers (mounting plates) transferred from the load lock

The specimen carriers must provide a convenient means to affix multiple small specimens with various sizes and thicknesses up to at least 2 mm (eg tapped holes or torsion clips). The overall specimen area must be large enough to accept a single 4” (100 mm) diameter circular specimen. At least 2 specimen carriers must be included.

The specimen stage and carrier must provide specimen heating and cooling.

It is preferable to use separate specimen stages for heating vs cooling. It must be possible to transfer the specimen carrier from the heated stage to the cooled stage without breaking vacuum. For example it might be desirable to heat the specimen to desorb water and hydrocarbons before cooling it to reduce diffusion and reaction during deposition. The cooled stage should utilize liquid nitrogen, bring the temperature of the specimen carrier below 150K within one hour, and maintain the temperature below 150K while evaporating a refractory metal (eg W) at 0.1 nm/s for 15 minutes. The temperature does not have to be precisely controlled when chilled below room temperature. A method of ensuring good thermal contact between the specimen carrier and chilled carrier holder must be provided. The vendor should provide sample temperature data under stated cooling conditions during e-beam deposition of tungsten.

Using the heated stage, the specimen carrier should reach at least 800oC maximum temperature. The specimen carrier temperature should be uniform to within 5oC while hot or cold. Temperature sensors, a heater power supply, and PID controller able to maintain the temperature within 1oC must be included. The heated components must be compatible with atomic oxygen.

Cooling must be provided to the un-heated parts of the chamber to reduce outgassing. Water cooling is preferred. if another liquid coolant is used, it must be non-toxic. A convenient means to remove the coolant during chamber bake and replace should be provided. Separate specimen carrier receivers can be used for heating and cooling.

The heated specimen stage should be electrically isolated from the chamber (while under vacuum) and connected to a vacuum feed-through such that the e-beam power supply can be used to excite a DC glow discharge plasma between the specimen and the chamber walls. An air-side connector and cable to the power supply must be included.

A remote-controlled substrate shutter covering the specimen area (but not covering the thickness monitor) must be included.

The distance from the top surface of the e-beam source to the sample position must be at least 300 and at most 350 mm for both heated and cooled stages.

l. A thickness monitor and control electronics

Interfaced with e-beam hearth power supply and shutter to provide automatic control of deposition rate and thickness

Crystal oscillator equipped with two crystals and an electronically-controlled shutter to expose either crystal, mounted in standard 0.55 inch temperature-controlled housing

Positioned to meter the deposition rate at all times.

Frequency range 1.0-6.5 MHz

Frequency resolution ±0.03 Hz

Rate display resolution 0.01A/s

Easy-to-read display of rate and thickness

Simple front panel control

Manual control possible

USB digital interface

Internal storage for multiple deposition processes

The control must be equipped with windows-compatible software able to create process recipes on a PC for upload.

m. The system must be equipped as follows:

Pneumatic valves and interlocks must be provided such that the chamber will not vent in the event of a loss of electric power.

All actuators must be controlled by a central electronic control.

The main chamber must include total pressure gauges and controller with computer interface able to read between 1 atm and 1E-10 torr.

An electronically-controlled shutter blocking the flux from the e-beam source to the sample. The shutter must not block the thickness monitor, such that the deposition rate can be monitored when the shutter is closed.

Mounted on a frame with both casters and adjustable leveling feet.

Plumbing for cooling water including flow rate monitoring interlocks preventing operation of the atom source and e-beam hearth without water cooling.

Interlocks preventing operation of the atom source and e-beam hearth at excessive pressure or temperature.

n. A water chiller/circulator with capacity sufficient to provide cooling to all system components.

o. Facilities requirements:

Electric power input is to be 208 VAC 3-phase (not greater than 60 A) with ground. The main power must be routed through a switch. One additional 208 VAC single phase circuit (not greater than 30 A), and/or one 110 VAC single phase (not greater than 20 A) circuit is also acceptable.

Footprint of working assembly not to exceed 10’ wide x 44” deep.

Unassembled components must be less than 84”x44” x 78” high.

NRL will supply compressed N2, O2, and H2 source gasses, compressed air at 60-90 psi, dry nitrogen at 30-60 psi, liquid nitrogen at 10-20 psi.

p. Optional Requirements:

1. Residual gas analyzer able to measure the partial pressure of molecular masses to at least 100 amu and suitable for helium leak checking and general purpose analysis. The analyzer must include a multiplier such that it is sensitive to partial pressures below 1E-11 torr. The analyzer must be mounted on one of the unused conflat ports in a location that prevents contamination from the e-beam flux. It must use computer control and provide control software for Windows OS.

2. Upgrade plasma source to produce ions at energies up to at least 500V.

3. Integrated software control of both the plasma atom/ion source (gas, power, flow rate) and e-beam hearth (crucible, power)

4. Boron nitride discharge tube

5. Silica discharge tube.

6. Differential pumping package for plasma source

7. Upgrade main turbo to higher pumping speed

8. A heater and temperature control system suitable for baking the main chamber. NRL anticipates that the heat for baking will be a combination of external heaters and the specimen heater. Ovens that must be removed are discouraged.

9. Spare gaskets for conflat flanges larger than 10”

10. Spare e-beam filament

11. Fab-mate crucible liner for e-beam hearth

12. Boron nitride crucible liner for e-beam hearth

2. Delivery: Delivery must occur within 6 months after approval of the system description. The purchase price must include all shipping costs. Delivered shipping containers must be less than 6’x8’x80” tall to fit within elevator. Uncrated parts must be less than 44” wide and 80” tall to fit through doorway.

3. Installation and Training: The purchase price must include onsite installation and training for at least two NRL personnel. NRL will install required utilities prior to system installation, including electric power and compressed air. The date of installation and training will be determined for mutual convenience.

4. Acceptance: The system will be accepted upon approval of the system manual and successful completion of installation and training at NRL.

5. Warranty and Support: All non-consumable hardware must be warranted for at least 1 year. The contractor shall offer the Government at least the same warranty terms, including offers of extended warranties, offered to the general public in customary commercial practice. The contractor must be able to supply advice, parts, and service from a US location in a timely manner. The contractor shall offer the Government the same or lower cost for parts and service offered to the general public in customary commercial practice. The contractor must have an established track record of support and service. The contractor must supply three previous customer references with the proposal.