As the first substrate 101, a substrate including a composite material of an organic material and an inorganic material may be used as well as a substrate including an inorganic material. Examples of a substrate including an inorganic material include a glass substrate, a ceramic substrate, and a metal substrate. Examples of a substrate including a composite material of an organic material and an inorganic material include a lamination of a resin substrate and an inorganic material, fiberglass-reinforced plastics (FRP), and a prepreg.
As the second substrate 102, a substrate including a composite material of an organic material and an inorganic material may be used as well as a substrate including an inorganic material, as in the case of the first substrate 101. Note that the second substrate 102 is provided such that a region capable of transmitting the energy ray overlaps with the sealant 131.
Here, the energy ray that can be used in the sealing step will be described. There is no particular limitation on the energy ray as long as it can propagate energy locally to a portion irradiated with the energy ray. For example, examples of the energy ray include a particle beam (e.g., an electron beam), an electromagnetic beam (e.g., a light beam or a microwave beam), and an ultrasonic beam.
In particular, a light beam emitted from a laser (also referred to as a laser beam) is favorable. With the use of a laser beam, energy with high density can be selectively absorbed by the sealant 131 without being absorbed by the second substrate 102.
Note that the wavelength of the light beam may be selected in consideration of a combination between the second substrate 102 and the sealant 131, and any of ultraviolet light, visible light, and infrared light may be used.