The method includes preparing a plurality of light-emitting units, one of the plurality of light-emitting units comprising an electrode, a light-emitting stack, and a protection layer with a first part covering the electrode and a second part which comprises a portion surrounding the electrode and covers the light-emitting stack; removing the portion without removing the first part; forming a wavelength conversion layer on the first part and the light-emitting stack not covered by the second part; and removing the first part to substantially expose the electrode.