In order to boot from an SD card, your BIOS must support it. Some BIOS support it and some do not. Go into BIOS and look for an option to enable Secure Digital (SD) Card Boot. It may be under the Boot tab, or it may be under System Configuration and something like Miscellaneous Devices or Other Devices. If you cannot find such an option in BIOS, then it won't be possible to boot from an SD card in the onboard SD card slot. You may be able to boot from SD card when connected via a USB card reader.
I know that, it's easy to use an USB drive for install the recovery tool(To make a bootable device.). But because its hard to find a USB and they are too expensive, can i use a Micro SD card to create the tool ?(To install the Dell recovery tool.).Can someone explain me this. 
I have a question about creating a bootable device for Dell Recovery Tool.