Refurbishing a Nikon Stepper : A SDI Success Story

The scope of the project described here was of allowing our client to see the Nikon NSR 1755i7A stepper we have in temperature controlled storage working and exposing wafers to the best possible resolution at our clean facility in Avezzano, Italy, and then crating the equipment for shipment to our customer.

Required Environment

In order to succeed putting into the best working environment conditions the Nikon Stepper, the following were the required actions to be taken:

  • temperature in clean area needed to be tabilized to 21° degrees Celsius with 1° degree tolerance.
  • A cleanroom at class 10 level, to allow easy measurement of exposed wafers without excessive contamination levels.
  • the stepper requires a supply of clean , particle free, 4ry air.
  • the stepper requires vacuum.
  • the stepper requires 18 l/min cooling water at 21° Celsius.
  • the stepper requires about 25 KW electricity supply, i.e. about 25A / phase 3 phase 5 wire.

Meeting the requirements

 

Stabilized temperature

This was achieved via a Sharp air conditioner/heat pump model AY-XP-18GR of capacity 5.0 kW in cooling and 5.7 kW in heating. Maximum power consumption is 2.8 KW. To avoid heat generation, the cleanroom is lit using exclusively fluorescent lamps.

 

A class 10 cleanroom

This was achieved using a total of 16 filter fan units mounted in a cleanroom area of 20 square meters.

The frame of the cleanroom was constructed in steel with plexiglass panels screwed onto the steel frame and glued in place with low particle production silicon sealant.

The floor is covered with anti-static cleanroom tiling with an earthed grid running under the floor, with 2 earthing points to prevent the buildup of electrical charges within the cleanroom structure.

The chase area is separated from the clean area at a height of 70 cm. The gowning area is situated in front of the entrance door and includes a further two filters to provide a laminar flow during gowning.

Measurements with a PMS Lasair 110 (see picture on the right) showed that the cleanroom was at class 10 level.

During operation at class 10 levels, personnel wear cleanroom clothing consisting of a full body cleanroom suit, a mutex hood, face mask, plastic overshoes and gloves.

 

Supplying clean, particle free dry air

 

We achieved this via a Kaeser SX6 4KW screw compressor, a reservoir, a Kaeser model DC5.8 dryer, and a series of 3 particle filters.

The compressor has a maximum 9 bar operating pressure. The reservoir is of capacity 500 litres. There is a filter type Kaiser ZK01 between the screw compressor and the 500 litre reservoir. There is an Kaiser Ecodty 21 plus filter unit on the air outlet of the reservoir.

At the outlet of the air dryer are mounted 2 air particle filters, Kaiser FC10 and FFG10.

 

Creating Vacuum

In order to provide vacuum to the equipment, an Edwards E2M40 oil rotary backing pump was used.

 

The Water Cooling system

As the stepper requires 18 l/min cooling water at 21° Celsius, we investigated different options.
Our initial plan was to use Neslab chillers.
However, it was discovered that the pumping capacity of the chillers was insufficient to generate the required pressure at the machine water inlet.
The pressure and the flow were monitored, and we connected 3 Neslab HX150 units in parallel.
This produced a flow of about 10 l/ min at 2-3 bar inlet pressure, which was not sufficient.
We then connected an electric wafer pump of capacity 20-70 l/min and power consumption 3.75 kW on the inlet line.
We fitted the pump with a safety cutout system to avoid damage to the pump in the case that water supply was interrupted.
The atmospheric pressure reservoirs of the Neslab HX 150 chillers were connected using tubing of 50 mm diameter so as to allow any flow imbalances to be obviated.
The above system was able to supply to the machine in operation a flow of around 20-22 litres/minute of cooling water at a temperature of circa 18° Celsius at the ingress.
The supply was at a pressure reaching peaks of 5 bar. The internal diameter of the tube to supply the machine was 12 mm.
It would be possible, and desirable, to increase the flow and reduce the required inlet pressure by increasing the diameter of the water supply pipe to an ID of 20-30 mm. We measured the water flow rate using a Kobold DFWMA water flow meter.

 

Starting up the system

After the stepper had been positioned in the cleanroom, we levelled the system, and connected the facility supplies, checking their correct functioning.
We re-charged the refrigerant and checked the beam delivery optics, together with the alignment system. We then overhauled the stage and we run a stage drive test to test accuracy. The power of the lamp transmitted to the wafer surface was verified.
We exposed pre-coated wafers using the Nikon test reticle, and regulated focus.
We then manually developed the exposed wafers in a photoresist developer bath.

The wafers were observed using an Olympus BHMJL inspection microscope, with a maximum 50X magnification.
A Sony digital camera with 3x optical and 10x digital zoom was mounted on the microscope and photos of the wafer showing a resolution of better than 0.45 um were obtained by illuminating the wafer with a 100 watt 12 V light source.

 

Crating and loading the equipment

 

Here you can see photo galleries related to the crating and loading the Nikon Stepper.

Crating

 

Loading

 

Search for Nikon used equipment available at www.fabsurplus.com

Modifying and Installing an Ultratech Stepper : a success story

The scope of the project described here was to remove an Ultratech Titan GH Line stepper taking it from operating in the cleanroom in Europe, transporting it to our client in the USA, modifying the stepper to run 5 inch reticles and 6 and 8 inch wafers ,installing it , and then subsequently demonstrating it operational to OEM specifications.

Success in this project was achieved by careful planning at each stage, and close work together with our suppliers and our client.

Ultratech Stepper Assessment and Removal

At fabsurplus.com,our aim is to minimise the risk to the client and maximise the profit return by providing reliable used equipment. To this end, the initial work of the project was:-

  • Thoroughly test the Ultratech stepper prior to removal
  • Performance was measured by running auto-uniformity at various field sizes to check illumination.When auto-uniformity was run with the large aperture, it was discovered that the light pipe was 55 x 18.
  • The reticle and wafer loading system was excercised and no problems were found.
  • Short step focus was checked and verified.
  • Software was backed up to floppies.

It was planned to repeat all tests done on removal again on install, then convert to 5 inch reticle and 8 inch/ 6 inch setup with universal chuck. System was prepared for removal by de-cabling and marking cables, removing sensitive subsystems etc. Main body of system removed from clean room to packing area. Main body packed in crate. Chamber dismantled and removed from clean room to packing area. Racks and all other parts removed from clean room to packing area. Crates shipped via air to USA.

Ultratech Stepper Installation in the USA

the following steps were perfomed during install:-

  • Cassette boat platforms modified to allow 8 inch wafer use.
  • The robot was set up for 6 and 8 inch wafer use.
  • Reticle Position Test was performed.
  • Short Step Focus was verified to be 1 um, D.O.F.=3um. Ran RM5 and updated variables. Ran SXS Overlay, 2 wafers. Results good. Cycled several wafers, all ok. Cycled reticle several times ok.
  • All tests that were carried out at decommission had been repeated during the install and were succesfull.
  • The original 5 inch chuck was replaced with a universal chuck and the vacuum lines were appropriately modified.
  • The system was then converted from 6 inch reticle setup to 5 inch reticle setup.
  • Ultratech stepper move into climate controlled chamber
    After conversion, the reticle loading was calibrated and thoroughly tested.
    In order to allow the client to achive a field width of over 26 mm, the 55 x 18 lightpipe was removed and replaced with a 44 x 22 lightpipe.The illuminator was moved to increase the field size.
  • The modified 8 inch cassette platforms were added.
  • The MVS was setup and operation was verified
  • The machine was handed over to production for testing.

Used KLA-Tencor Inspection and Metrology Equipment refurbishment capabilities

Based on the 20 year experience of our staff members, SDI-Fabsurplus has been developing the capability to support and refurbish KLA-Tencor wafer inspection , particle detection and metrology systems and install them to OEM specifications.
Since September 2011, Fabsurplus.com has further expanded it’s technical support capabilities by appointment of a lead KLA support engineer. SDI-Fabsurplus is therefore now happy to quote for refurbishment, programmed maintenance, service interventions, laser changes, training and matching worldwide on surface scan wafer particle detection products.

Example Project: Refurbishment and Turnkey Installation of a KLA AIT particle detection system

An example of a successful KLA Surfscan refurbishment project was the consignment to our client
of a KLA AIT wafer surface particle inspection system.

The system was completely refurbished at our Avezzano, Italy refurbishment centre, the functionality to OEM specifications was checked and then the system was consigned to our client and installed and tested on site.

Required Environment

Due to the sensitivity of KLA systems to changes in environmental conditions and particle levels, a key to our success has
been establishing a clean facility where we have control over the environmental factors in our error budget during system
refurbishment.
This allows us to concentrate on optimising performance of the system to and beyond OEM specifications,
and will give us leeway in performance to allow for any unexpected problems we might encounter on site during system install.

In order to succeed putting into the best working environment conditions the KLA AIT,
the following were the required
actions to be taken:

 

AIT1 SYSTEM FACILITIES

1. Air Pressure, facility requirement

The facility supply pressure to the system inlet regulator must be a minimum
of 85 PSI @ maximum flow rate of 4 SCFM and not exceed 105 PSI @ 0 SCFM.
The CDA/N2 must be dry to -20 degrees Fahrenheit and filtered to 0.1 microns.

2. Vacuum requirement

The system vacuum must greater than 20” (Hg) @ 0.5 CFM at the TECO panel inlet of the system.

3. Venting

a)Blower Exhaust

Blower A, Laser exhaust
75 CFM, discharging at 2100 BTU per hr./ 5 mw (standby)
CFM, discharging at 2800 BTU per hr./ 10 mw
CFM, discharging at 3500 BTU per hr./ 30 mw
Blower B, System exhaust
105 CFM, charging 4000 BTU per hr. at all Laser powers

 b)Purge (Particle collector)

Approximately 5” Hg of vacuum at the facility outlet regulator

4. Vibration, Floor

Refer to Preinstallation Guide, Tencor P/N 348325

5. Environmental requirements

Temperature: 66 to 70 Fahrenheit,
Humidity: Standard Fabrication environment (> 30%)
Air Quality: Federal Standard 209 Class 10 or cleaner environment

6. AC power requirements

Power:  Europe 220 VAC +/- 10%  30 A 50 Hz
 

Meeting the requirements

Stabilized temperature 

This was achieved via a Sharp air conditioner/heat pump model AY-XP-18GR of capacity 5.0 kW in cooling and
5.7 kW in heating.

Maximum power consumption is 2.8 KW.

To avoid heat generation, the cleanroom is lit using exclusively fluorescent lamps.

A class 10 cleanroom

This was achieved using a total of 16 filter fan units mounted in a cleanroom area of 20 square meters.
The frame of the cleanroom was constructed in steel with plexiglass panels screwed onto the steel frame
and glued in place with low particle production silicon sealant.
The floor is covered with anti-static cleanroom tiling with an earthed grid running under the floor, with
2 earthing points to prevent the buildup of electrical charges within the cleanroom structure.
The chase area is separated from the clean area at a height of 70 cm. The gowning area is situated in front
of the entrance door and includes a further two filters to provide a laminar flow during gowning.
Measurements with a PMS Lasair 110 showed that the cleanroom was at class 10 level.
During operation at class 10 levels, personnel wear cleanroom clothing consisting of a full body cleanroom
suit, a mutex hood, face mask, plastic overshoes and gloves.

Supplying clean, particle free dry air

We achieved this via a Kaeser SX6 4KW screw compressor, a reservoir, a Kaeser model DC5.8 dryer, and a
series of 3 particle filters.
The compressor has a maximum 9 bar operating pressure.
The reservoir is of capacity 500 litres.
There is a filter type Kaiser ZK01 between the screw compressor and the 500 litre reservoir.
There is an Kaiser Ecodry 21 plus filter unit on the air outlet of the reservoir.
At the outlet of the air dryer are mounted 2 air particle filters, Kaiser FC10 and FFG10.

Creating Vacuum

In order to provide vacuum to the equipment, an Edwards E2M40 oil rotary backing pump was used.

Starting up the system

After the AIT had been positioned in the cleanroom, the system was powered up and the performance was checked. 
It was observed that the PMTs needed replacing and the Laser needed replacing.

The PMTs and laser were replaced and aligned.

The customer required to use the system with 6 inch wafers.

A new 6 inch chuck was manufactured and the stage was re-levelled,
 so as 6 inch wafer performance could be checked.

All OEM performance specifications were achieved and then the system was shipped to the client.

Installation of the system

The system was positioned by customer move-in team on the pedestal.
The system was set up again by SDI engineers and consigned to the customer.
Total install time was less than the 14 days programmed.

Conclusion

SDI was able to consign and install a KLA AIT system at our clients fab
for a fraction of the cost of a newer tool from the OEM.

The customer was able to purchase the tool from his maintenance budget during a spending freeze on new capital equipment.
He did not require the performance of the newer KLA tools, as his product was typically at the 0.5 um technology node.

Buy and sell KLA-Tencor refursbished equipment with fabsurplus.com

SDI’s aim is to help our customers properly and efficiently purchase, use and re-use semiconductor manufacturing equipment,
saving money for the buyer and the seller.
SDI can supply a range of refurbished KLA tools installed and guaranteed functional to OEM specifications,
from Brightfield inspection tools, laser surface inspection tools, reticle inspection tools to CD SEMS and surface profilometers.

Click here for a list of available KLA equipment at SDI fabsurplus.com (also Tencor and Prometrix)
Reticle Defect Inspection

Brightfield wafer defect inspection

Ellipsometer

Dektak

Profilometer

Macro Defect Inspection

Darkfield wafer defect inspection

Scanning Electron Beam Microscopes

Resistivity Measurement

4 Point Probe

Cv Measurement

Carrier Lifetime Measurement

Surface Particle Detection Equipment

Overlay Measurement Equipment

Emmi

Stress Measurement