Leica EM ACE600 Carbon & Iridium Coating System

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1 Leica EM ACE600 Carbon & Iridium Coating System Standard Operating Procedure Revision: by Michael Paul Overview This document will provide a detailed operation procedure of the Leica EM ACE600 carbon and iridium coating system. Formal Training is required for all users prior to using the system. Revision History # Revised by: Date Modification 1 Matt Bilton First version with incomplete carbon sharpening 2 Michael Paul New UI images, vacuum conditions, presputter, finish procedures, and carbon rod reshaping procedures Document No. 4DSOPACE600_1 1

2 Table of Contents Overview... 1 Revision History... 1 Table of Contents... 2 General Information... 3 Main components:... 4 Safety... 5 Instrument Overview... 6 Operation... 7 Sample Loading... 8 Carbon coating... 9 Iridium coating Glow Discharge Creating your own process (Carbon Evaporation, Ir Sputtering or Glow Discharge) References and Files Contact Information

3 General Information The Leica EM ACE600 coating system is used for precise coating of samples for subsequent examination with an electron microscope (EM). Carbon and iridium angled coating sources are configured. Automated stage rotation is integrated for best distribution. Integrated quartz crystal measurement accurately determines the layer thickness. Automated or manual height and tilt adjustment. Glow discharge capability to makes samples/ TEM grids hydrophilic. The samples are iridium coated using the sputtering method where argon plasma erodes a target material. Carbon coating is achieved by carbon rod evaporation. Any sample can be processed as long as it is not sensitive to vacuum, argon plasma or the heat generated during carbon coating. The Leica EM ACE600 coater is configured with the following processes: iridium sputtering, carbon rod evaporation, and glow discharging. The removable shielding, shutter, source and door are designed to enable easy and comprehensive cleaning of the system. The vacuum system creates an ultimate vacuum 1.5 x 10-6 Torr. Pressure is monitored by a combined thermal and cold cathode vacuum gauge (refer to Leica ACE600 full operation manual for all specifications). 3

4 Main components: The Leica EM ACE600 coating system includes the following main functional units, depending on the configuration: Vacuum chamber, Touch screen control panel, Rotating sample stage, 25 positions for 12.5mm SEM stubs, Removable shielding, shutter and door, Housing, Quartz (QSG) thickness measurement Carbon rod source, Iridium source Glow discharge 4

Safety All electronic components are protected by covers: door lock (1), source cover (2), housing (3). The door and source covers are equipped with sensors which cut off power when they are opened.

5 Safety All electronic components are protected by covers: door lock (1), source cover (2), housing (3). The door and source covers are equipped with sensors which cut off power when they are opened. Additionally, there are software switches which cut off power when a malfunction is noticed Figure 1: LEICA ACE600 There is an overheat protection for the sources. When reaching 65 C the process is stopped until a temperature of 45 C is reached then the process automatically continues. When there is a sudden vacuum break down the instrument switches off automatically to protect pump and electric parts. The housing must not be opened except by an authorized Leica representative. If the Leica EM ACE600 coating system is damaged or malfunctions, all use of the system should be suspended until the malfunction or damage has been corrected. All modifications and conversions to the system are prohibited and invalidate the warranty. Please report any concerns to the tool owners. 5

authorised Chamber Shutters Chamber door Quartz crystal Sample

6 Instrument Overview Source Head (Carbon rods) Do not open unless authorised Source Head (Iridium) Do not open unless authorised Chamber Shutters Chamber door Quartz crystal Sample stage Touch screen control panel Figure 2: Components of Leica ACE600 6

Operation The system must remain under vacuum when not in use. The touch screen displays the current vacuum level; this should typically be in the region of 10-6 Torr.

7 Operation The system must remain under vacuum when not in use. The touch screen displays the current vacuum level; this should typically be in the region of 10-6 Torr. The colour scale bar also indicates the level of vacuum. Figure 3: Vacuum status At the end of your session, ensure your samples are removed, and that the chamber is door is closed. Then press Pump to leave the system under vacuum. 7

Sample Loading To vent the system, press Vent. Wait until the vacuum level reaches between 6.0 x 10 +2 to 7.6 x 10 +2 Torr. Test the vacuum evacuation level by lifting the door handle.

Once the chamber has been vented, gently lift the door handle to open the chamber. The sample holder can hold 25 x 12.5mm SEM stubs.

8 Sample Loading To vent the system, press Vent. Wait until the vacuum level reaches between 6.0 x to 7.6 x Torr. Test the vacuum evacuation level by lifting the door handle. The door should open without the use of any force, wait a few minutes if the door does not open freely. Do not use force to open the door. Once the chamber has been vented, gently lift the door handle to open the chamber. The sample holder can hold 25 x 12.5mm SEM stubs. It mounts to the stage using a pin that must align to the inner most hole on the sample holder (marked red in Figure 4). Gentle lift the stage from the pin to remove. (a) (b) Figure 4: (a) Sample holder, and (b) SEM stub Handle the stage with clean nitrile gloves at all times. Remove and replace the holder carefully and without disturbing the central quartz crystal at the centre of the stage. Only use samples that will fit securely into this holder, and ensure that your samples are not loose as they are likely to fall during rotation or tilting of the stage. Speak to a tool owner if you have different shaped samples that you wish to coat or apply a glow discharge. 8

9 Carbon coating Carbon evaporation coating uses two 3mm carbon rods, one with a sharpened end. These are pushed against each other and a current is applied to produce a fine grained carbon coating. To ensure an optimum coating, carbon rods require very regular sharpening. Only tool owners and authorized trained users may handle and sharpen the carbon rods. Should you wish for the rods to be sharpened before you use the system, please ask an authorized person to do this for you. It may be advisable to request this in advance of your instrument booking. For regular users who wish to be trained in sharpening the carbon rods, please speak to a tool owner. 1. To begin carbon coating using the default setting, select Evaporation on the touch screen home page. Figure 5: Home page 2. This will display the preset process for carbon evaporation. You can select your desired vacuum level (high vacuum; < 10-5 T is recommended) coating thickness/time, set your sample height (for most flat SEM stubs this will be about 3mm), working distance (50 mm recommended), stage rotation speed, and tilting angle (-25 to tilt towards C-rods). 9

10 Figure 6: Carbon evaporation 3. Press Start to begin coating process. 4. When complete, the system Vent should start venting immediately according to the default recipe. Press Init on the process result screen to home the stage to its default position and close the screen to go back to the main screen (Figure 7). Figure 7. Process result screen 10

5. If the screen was closed by accident without homing the stage. Go to Menu System tab, and select Init at the top right to home the stage (Figure 8). Figure 8. Stage homing process 6.

11 5. If the screen was closed by accident without homing the stage. Go to Menu System tab, and select Init at the top right to home the stage (Figure 8). Figure 8. Stage homing process 6. Once the system is vented and chamber door opened, remove your samples carefully. Replace the sample holder and press Pump to put the chamber under vacuum. Ensure that the chamber door is closed and that the pump has started before leaving. Figure 8. Chamber pump down 7. If you wish to create your own coating processes, please see following Section Creating your own process (Carbon Evaporation, Ir Sputtering or Glow Discharge) on page

12 Iridium coating Magnetron sputter coating is performed using ionized argon to create a plasma. The argon-ions are accelerated by high voltage and directed towards the source via a magnet where they collide with the target and displace surface atoms. Due to this collision the surface atoms are directed towards the area below the target and coat the sample. This coating process can be more directional, i.e. produce finer grains (sputtering at higher vacuum, 10-5 Torr) or diffuse, i.e. slower rate to create a more even coating on a bigger surfaces and fissured samples, (sputtering lower vacuum, 10-2 Torr). With the quartz thickness measurement (QSG) the layer thickness can be calculated as a result of the changed quartz crystal resonance frequency (refer to Leica Operating Manual for further details). 1. To begin iridium coating using the default setting, select Sputtering on the touch screen home page. Figure 7: Home page 2. This will display the preset process for iridium sputtering. You can select your desired coating thickness/time, set your sample height (for most flat SEM stubs this will be about 3mm), working distance (50 mm recommended), stage rotation speed, and tilting angle (+25 to tilt towards Irtarget). 12

13 Figure 8: Iridium sputtering 3. Press Start to begin coating process. 4. Follow the step 4-7 on page for the system turn down procedures that includes homing the stage and pumping down the chamber. 5. If you wish to create your own coating processes, please see following Section Creating your own process (Carbon Evaporation, Ir Sputtering or Glow Discharge) on page

14 Glow Discharge The glow discharge is an optional process which is used mainly to make TEM grids hydrophilic. It is also useful for cleaning carbon-contaminated TEM samples, for improved high-resolution imaging. Argon is used to create plasma. This process can also be used to clean the sample surface before coating. After choosing a protocol the system will perform the following steps automatically: Pumping until process vacuum is reached Bleeding in air to adjust vacuum to set pressure Stabilizing vacuum and starting glow discharge with closed shutter (purple plasma is visible) Termination of glow discharge process by the set time Displaying the results of the process Venting or staying in vacuum 1. To begin a glow discharge process using the default setting, select Glow Discharge on the touch screen home page. Figure 9: Home page 14

2. Here you will observe the glow discharge screen (Figure 10). You can edit your desired discharging time and set the correct sample height for your sample. Figure 10: Glow discharge 3.

15 2. Here you will observe the glow discharge screen (Figure 10). You can edit your desired discharging time and set the correct sample height for your sample. Figure 10: Glow discharge 3. Press Start to begin the process. 6. Follow the step 4-7 on page for the system turn down procedures that includes homing the stage and pumping down the chamber. 4. These settings will be sufficient for most users, however if you wish to create your own coating processes, please see following Section Creating your own process (Carbon Evaporation, Ir Sputtering or Glow Discharge) on page

16 Creating your own process (Carbon Evaporation, Ir Sputtering or Glow Discharge) 1. If you wish to alter your stage geometry (e.g. stage rotation speed, working distance, and stage tilt), tap the Characteristics window in the Process screen (Figure 11) will bring up the Process Manager screen (Figure 12) Figure 11: Manage Processes (1) Figure 12: Manage Processes (2) 16

17 2. Do not modify the default presets or presets defined by other users, press Add (Figure 12) to create a new process Figure 13: New process added 17

Reference source not found.4: Edit screen for the processes. 4.

18 3. Once a new process is created (Figure 13) click anywhere at on the corresponding options (Method, Stage, Vacuum) to bring up the menus for changing the parameters required. Figure 14 shows the corresponding menus for each of these options. Error! Reference source not found.4: Edit screen for the processes. 4. For the sputtering Methods screen, ensure Presputter (default is OFF) is checked for pre-deposition of materials with closed shutter for 60 s to ensure the uniformity of sputter (Figure 15). Figure 15: Method edit screen 18

Carbon-rod sharpening For the most even and accurate carbon coating, a carbon rod must be regularly sharpened to minimize the contact area between the 2 rods.

19 Carbon-rod sharpening For the most even and accurate carbon coating, a carbon rod must be regularly sharpened to minimize the contact area between the 2 rods. Reshaping of the carbon rods must be done roughly every 20 nm of coating. Please ask a tool owner to show you how to carry out rod sharpening. Carbon rods are delicate and must always be handled with care. Wear gloves at all times when handling the carbon rods, and tool accessories. Required tools Assemble the following set of accessories to use for the carbon-rod sharpening procedure. These can be found stored in the box on the shelf behind the coater system. 1. 2,5 Allen key 2. Brush to remove loose carbon 3. Special tool for mounting the carbon rods 4. Special tool keep the carbon rod evaporation source open for mounting 5. Carbon rod sharpener 6. Copper clamps for carbon rod 7. Special holding tool for the carbon rod clamps 8. Special tool to hold the carbon rod for sharpening 9. Carbon rodscarbon rods (only use a new rod if the existing rods can no longer be used. Always check with a tool owner before using a new carbon rod) Figure 16. Carbon rod re-shaping tools 19

Removing Carbon-rods 1. Press VENT to vent the system. 2. Wait until the vacuum level reaches between 6.0 x 10 +2 to 7.6 x 10 +2 Torr. Test the vacuum evacuation level by lifting the door handle.

20 Removing Carbon-rods 1. Press VENT to vent the system. 2. Wait until the vacuum level reaches between 6.0 x to 7.6 x Torr. Test the vacuum evacuation level by lifting the door handle. The door should open without the use of any force, wait a few minutes if the door does not open freely. Do not use force to open the door. Once the chamber has been vented, gently lift the door handle to open the chamber. 3. Close the chamber door 4. Lift up the upper covering of the system to reveal the sputter and C evaporation sources Figure 17. C evaporation source cover and carbon rod holders 5. Open the Carbon Rod Source Head by unscrewing the 2 screws (see Error! Reference source not found.), and carefully remove the cover. Set the cover safely aside. (Figure 17) 20

Figure 18. Inserting the mounting tool 7.

21 6. Use one hand to push the Sharp carbon rod holder away from the other carbon rod. Align the shape of the special mounting tool to hold the carbon rod at an OPEN position (Figure 18). Figure 18. Inserting the mounting tool 7. Screw on the carbon rod holder handle and loosen the LOWER screw with the allen key to remove the carbon rod holder (Figure 19). Figure 19. Removing the carbon rod holder 21

The flat rod should be placed at the side that is closer to the alignment edge.

22 8. Repeat the step 7 to remove the other carbon rod holder (Figure 20) Figure 20. Removing the other carbon rod holder 9. Slightly flatten the flat carbon rod on a piece of sandpaper. Put the rod holder onto the alignment tool. The flat rod should be placed at the side that is closer to the alignment edge. Loosen the holding screw and slightly lengthen the rod over the alignment edge. Use a straight edged tool to push the rod down to align with the edge. Retighten the rod holding screw. (Figure21.) Figure 21. Aligning the flat carbon rod 22

Insert the sharpened rod back into the holder, and place the holder onto the alignment tool.

23 10. Remove the sharp rod from the rod holder and insert it into the sharpener holder. Sharpen the rod with a circular motion until a maximum sharpness is achieved (shown in Figure 22). Figure 22. Carbon rod sharpening 11. Insert the sharpened rod back into the holder, and place the holder onto the alignment tool. Align the sharpened rod to the opposing alignment edge of the flat rod with similar procedures in step 9. (Figure 23.) Figure 23. Both carbon holders in the alignment tool with rods properly aligned 23

12. Ensure the carbon rod holding screw is tighten. Note: This has to be fairly tight, to hold the rods down securely. 13. Put the rod holders back into their positions on the evaporation stage.

(Figure 24) Note: If the rods were not tightened sufficiently, the rod will slide in the holder. If sliding occurs, the rod holders will need to be removed and the rods realigned. Figure 24.

24 12. Ensure the carbon rod holding screw is tighten. Note: This has to be fairly tight, to hold the rods down securely. 13. Put the rod holders back into their positions on the evaporation stage. Note: The flat rod is placed at the lower holder position. While supporting the upper rod holder. Remove the separator tool. Gently remove the sharp rod down in contact with the flat rod. (Figure 24) Note: If the rods were not tightened sufficiently, the rod will slide in the holder. If sliding occurs, the rod holders will need to be removed and the rods realigned. Figure 24. Two carbon rods in contact with each other on the evaporation stage. 14. Use an air duster to clean the stage/cover of any particle and debris. Use kimwipe and alcohol (isopropanol or ethanol) to clean the cover seat, the cover, and the O-ring on the cover. Replace the cover and tighten the screws.(figure 25) Note: The thumb screws should only be tightened slightly to ensure the O-ring is free of deformation for good vacuum sealing. Figure 25. Cleaning and replacing the evaporation stage cover 24

25 References and Files Leica EM ACE600 Operating Manual and training notes. Contact Information Questions or comments in regard to this document or the Leica EM ACE600 system should be directed towards Michael Paul or Xin Zhang ) in 4D LABS at Simon Fraser University, Burnaby, BC, Canada. 25

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