Specific Process Knowledge/Lithography/UVExposure/aligner MA6-2

Aligner: MA6-2

The Aligner: MA6-2 is located in E-4.

Tool description
The Aligner: MA6-2 is a manual UV exposure system, which can be used for mask alignment and exposure of UV resists on chips, 50 mm, 100 mm, and 150 mm substrates.

The Süss MicroTek Mask Aligner MA6 is designed for high resolution photolithography. The 365nm exposure wavelength version is capable of 1.25 (1.0) um resolution in vacuum contact. All contact exposure programs (vacuum, low vacuum, hard, soft, proximity) are supplied. Two alignment options are available: top side alignment (TSA) with a split field or a video microscope and back side alignment (BSA) with BSA (video) microscope.

The aligner can also be used for bond alignment (for Wafer Bonder 02). Special training is required.

Product:	Süss mask aligner MA6
Year of purchase:	2014
Location:	Cleanroom E-4

User manual
The user manual and contact information can be found in LabManager - requires login

Tool training
Training on the tool requires users to complete the lithography TPT followed by the online tool training and a hands-on authorization training.
The tool training videos are part of the online tool training, but can also be viewed here (Operation) and here (Alignment).

Equipment performance and process related parameters

Purpose	Mask alignment and UV exposure Bond alignment
Exposure modes	Vacuum contact Hard contact Soft contact Proximity Flood exposure
Exposure light/filters	365 nm (i-line) broadband (i-, g-, h-lines), requires tool change 280-350 nm (UV300), requires tool change
Minimum resolution	~1.25 µm
Mask size	5x5 inches 7x7 inches Special holder for 4x2" designs on 5x5 inch
Alignment modes	Top side (TSA): ±1 µm (tool spec: ±2 µm) Back side (BSA): ±2 µm (tool spec: ±5 µm)
Substrate size	Small pieces: 1x1 cm 50 mm wafers 100 mm wafers 150 mm wafers
Allowed materials	All cleanroom allowed materials, except copper and steel III-V materials only allowed on dedicated chuck
Substrate batch	1

Process information

The Aligner: MA6-2 has an i-line notch filter installed. This results in an exposure light peak at 365nm. Compared to exposure on the KS Aligner, the optimal dose should be very similar. The 500W Hg-Xe lamp also enables exposure in the DUV range around 240nm. This functionality is not established yet, partly due to safety concerns.

Exposure dose

Information on UV exposure dose

Alignment mark design and locations

Alignment mark design and locations.

Light intensity and uniformity after lamp ignition

Light intensity and uniformity after lamp ignition. CP is constant power mode, CI is constant intensity mode. The accept limits for the CI mode is ±5%, the accept limit for the non-uniformity is 2%. CP mode has no accept limit.

The lamp requires about 15 minutes of on-time after lamp ignition, before the light output has stabilized, and users using the constant power mode should always wait for 15 minutes after ignition, before starting processing.

If users use the constant intensity mode, this waiting time is not necessary, since the internal light sensor automatically adjusts the output to match the setpoint value.

The non-uniformity of the light, in CI mode, is unaffected by the stabilization time.

Alignment

Top Side Alignment:

• TSA microscope standard objectives: 5x, and 10x (20x available)
• TSA microscope special objectives: 11.25x offset for smaller separation

• Minimum distance between TSA microscope objectives: 33 mm for standard objectives and 8 mm for the special objectives
  • Alignment of even smaller separations is possible using the "scan microscope" function
• Maximum distance between TSA microscope objectives: 160 mm
• TSA microscope travel range: X ±25 mm; Y +20/-75 mm (towards the flat)

Back Side Alignment:

• Minimum distance between BSA microscope objectives: 15 mm
• Maximum distance between BSA microscope objectives: 100 mm
• BSA microscope travel range: X +50/-16 mm; Y +50/-20 mm (towards the flat)
• BSA chuck view ranges:
  • 50 mm: X ±8-22 mm; Y ±0-6 mm
  • 100 mm: X ±14-46 mm; Y ±0-10 mm
  • 150 mm: X ±14-69 mm; Y ±0-10 mm

Microscope field of view (W x H, splitfield):

• TSA 5X:
  • Oculars: 1.3 mm x 2.6 mm (Ø2.6 mm full field)
  • Camera: 350 µm x 500 µm (700 µm x 500 µm full field)
• TSA 10X:
  • Oculars: 0.6 mm x 1.3 mm (Ø1.3 mm full field)
  • Camera: 150 µm x 250 µm (350 µm x 250 µm full field)
• TSA special:
  • Oculars: 0.55 mm x 1.1 mm (Ø1.1 mm full field)
  • Camera: 150 µm x 200 µm (300 µm x 200 µm full field)
• BSA camera:
  • Low: 1.5 mm x 2 mm (3 mm x 2 mm full field)
  • High: 450 µm x 650 µm (950 µm x 650 µm full field)

Quality Control (QC)

The purpose of the QC process is to check the intensity and uniformity of the exposure light in the Aligner: MA6-2, using a UV optometer. The optometer is placed at 5 fixed positions in the exposure area on a dedicated QC chuck, and the intensity of the light is measured.

The 5 intensity measurements are then used to calculate the average intensity as well as the peak uniformity error: $PUE[\mathrm{\%}]=\frac{max-min}{max+min}\cdot 100$.

Intensity accept limit:
The intensity should be corrected if the average intensity (from the 5 measurement points) deviates more than ±5% from nominal value. The nominal value for the Aligner: MA6-2 is 11 mW/cm², which means that the accept range is 10.45 - 11.55 mW/cm².

Uniformity accept limit:
The uniformity should be adjusted if the peak uniformity error is greater than 2%.

Documentation:

• The QC procedure for Aligner: MA6-2 - requires login
  
• The newest QC data for Aligner: MA6-2 - requires login