MLA 150 (DLA) Presentation and examples Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 1
Presentation of the tool The MLA 150 (named DLA in the past) is a new generation Maskless Aligner developed by Heidelberg Instruments GmbH in Germany. It has been installed at EPFL to test its capabilities. It is free of charge for the users who complete the feedback document (available on cmi website, under the description of the tool). All images and results are always welcome. This system allows researcher to quickly write a design on a wafer, without the need to order or produce a mask. Once the design is done, the MLA can read, align and expose it on a substrate within a few minutes. The system is equipped with: Exposure source: 405 nm laser diode 3 cameras: overview for quick crosses localization, macro and micro for automatic detection of alignment crosses Real time autofocus Stage system, position control with interferometers, chuck with vacuum for various substrate sizes And offers the following specifications: Minimum feature size: 1 um Uniformity: <100 nm Alignment accuracy: <500 nm (down to <200 nm depending to the size of the design) Maximum substrate size: 220 mm x 220 mm (9 x9 ) Maximum exposure area: 150 mm x 150 mm Designs compatibility: cif, gdsii, dxf, gerber The system offers two writing speed with the following exposure time. (The exposure time may vary depending on the complexity of your design) 30 minutes for a full wafer in quality mode 15 minutes in fast mode A dropbox, user manual, resist table and more information can be found on the PC of the MLA and on the CMI website: cmipc114/@public/documentation Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 2
Exposure The tool is equipped with a 405 nm laser diode. The top of the resist is automatically detected. There are then only two parameters to set: Dose: controls the dose [mj/cm2]. Keep in mind that the dose is not exactly the same as with a mask aligner Defocus: defines where the focus is done. If set to zero, focus is done on top of the resist and a positive defocus will shift the focus downwards inside the resist (range: -10..10, 10 being a shift of 6 microns) Please find in the following table dose and defocus parameters for several resists: Resist Thickness [um] Substrate Dose [mj/cm2] Defocus CD [um] AZ 1512 1.6 silicon 130-2 2 AZ 1512 1.1 silicon 90-2 1.2 AZ 9260 4 silicon 160 2 1.4 AZ 9260 10 silicon 300 3 1.8 AZ ECI 0.6 silicon 120-2 1 AZ ECI 1 silicon 160-2 1.2 AZ ECI 2 silicon 320-2 1.4 AZ ECI 4 silicon 650-2 1.4 AZ ECI 5 silicon 800-2 1.5 nlof impossible SU-8 alternative sensitive to a wave length of 405 nm (microresist.de) mr-dwl 40 silicon 250 350 0 10 2 mr-dwl 80 silicon 300 400 0 10 3 If you want to try other resists, other substrates or thicknesses, an automated dose test with various doses and focuses can be done in several minutes. Alignment capabilities If you want to perform an alignment with the MLA, you need to have 2 to 4 crosses on your design and you need to know the coordinates of those crosses in the coordinate system of your design. The MLA detects the center of the crosses. The design to be exposed is then centered and rotated to match the coordinates of the crosses. For example, standard CMI crosses for the mask aligner have the following coordinates: (-42000, 0) and (42000, 0) [um] Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 3
Examples AZ 1512 Figure 1: AZ 1512, 1.1 um thick, 2 um checkerboard Figure 2: AZ 1512, 1.1 um thick, pillars and holes with a diameter of 4 um Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 4
Figure 3: AZ 1512, 1.6 um thick, test structure Examples AZ 9260 Figure 4: AZ 9260, 10um thick, 4 um pillars Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 5
Figure 5: AZ 9260, 10um thick, 4 um and 2 um lines and spaces Examples AZ ECI Figure 6: AZ ECI, 0.6 um thick, 1 um space, 1.5 um resist lines Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 6
Figure 7: AZ ECI, 0.6 um thick, 1.5 um pillars with 1 um space Figure 8: AZ ECI, 5 um thick, 2 um lines and spaces Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 7
Figure 9: AZ ECI, 5 um thick, 4 um lines and spaces Figure 10: 100 nm gold line fabricated with a double patterning using AZ ECI 0.6um. Gold was etched with IBE. The first layer containing periodic 1 um lines and spaces was first exposed and etched with IBE. The second layer containing the same periodic 1 um resist lines and spaces but with 100nm overlap was then aligned and exposed. Gold lines are thus the result of the overlap of two different layers aligned with the MLA. Figure 10 shows the uniformity of exposure and the alignment capabilities. Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 8
Figure 11: AZ ECI, 0.6 um thick, horizontal 1 um lines and spaces Figure 12: AZ ECI, 0.6 um thick, vertical 1 um lines and spaces It is worth mentioning that overexposition is slightly higher in the vertical direction. Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 9
mr-dwl 40 (SU-8 alternative sensitive to 405 nm) This is an epoxy based negative photoresist developed by Microresist Technology GmbH in Berlin (microresist.de) for direct laser writing at 405 nm. Figure 13: mr-dwl 40, 80 um thick, cylinders Figure 14: mr-dwl 40, 80 um thick, 1-7 um lines (1 and 2 um lines delaminated) Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 10
Figure 15: mr-dwl 40, 80 um thick. It is possible to play with the focus to change the sidewalls of the exposed resist, in this case, the focus is 15 um downwards inside the resist Figure 16: mr-dwl 40, 40 um thick, 20 um pillars array Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 11
Figure 17: mr-dwl 40, 40 um thick, 20 um square pillars obtained with two different focuses. Figure 18: mr-dwl 40, 80 um thick, microfluidic mixer Théophane Besson, 17.03.2015, Heidelberg Instruments GmbH 12