This copolymer has a structural unit including a triazole skeleton that is any one or more of (1-1) to (1-3) (R.sup.1 to R.sup.6 are each any one selected from the group made of a hydrogen atom, a methyl group, a trifluoromethyl group, a nitrile group, a fluorine atom, a methoxy group, an ethyl group, an ethoxy group, a methoxymethyl group, a propyl group, an isopropyl group, a cyclopropyl group, a butyl group, an isobutyl group, a (trimethyl)methyl group, a (trimethyl) silyl group, a pentyl group, an isopentyl group, a t-pentyl group, a neopentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a phenyl group, a tolyl group, a benzyl group, and a phenoxymethyl group, or R.sup.1 to R.sup.6 each form a benzotriazole skeleton together with a triazole ring) and a structural unit represented by Formula (2).

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A method is disclosed of fabricating a MEMS device that includes one or more wafers configured as pump or valve. The pump or valve includes an inlet port to receive fluid and an outlet port to release the fluid within the pump or valve. The method comprises growing silicon dioxide on a silicon layer of the one or more wafers to form a silicon dioxide layer on the silicon layer, depositing silicon nitride on the silicon dioxide layer of the one or more wafers to form a silicon nitride layer on the silicon dioxide layer, spinning a front side to create a pattern thereon defining an area for the pump or valve, dry etching the one or more wafers at the area for the pump or valve to remove the silicon dioxide and silicon nitride layers to define an opening for the pump or valve.

A method is disclosed of fabricating a MEMS device that includes one or more wafers configured as pump or valve. The pump or valve includes an inlet port to receive fluid and an outlet port to release the fluid within the pump or valve. The method comprises growing silicon dioxide on a silicon layer of the one or more wafers to form a silicon dioxide layer on the silicon layer, depositing silicon nitride on the silicon dioxide layer of the one or more wafers to form a silicon nitride layer on the silicon dioxide layer, spinning a front side to create a pattern thereon defining an area for the pump or valve, dry etching the one or more wafers at the area for the pump or valve to remove the silicon dioxide and silicon nitride layers to define an opening for the pump or valve.

A crystal element includes a vibration part, a holding part, an electrode part, and a recess that corresponds to a recess and/or protrusion. The vibration part has a pair of vibration-part main surfaces. The holding part is formed integrally with the vibration part to be connected to an outer edge of vibration part and has a pair of holding-part main surfaces and holding-part side surfaces. The electrode part is provided at the vibration-part main surfaces. The recess is located at the holding-part side surfaces.

A crystal element includes a vibration part, a holding part, an electrode part, and a recess that corresponds to a recess and/or protrusion. The vibration part has a pair of vibration-part main surfaces. The holding part is formed integrally with the vibration part to be connected to an outer edge of vibration part and has a pair of holding-part main surfaces and holding-part side surfaces. The electrode part is provided at the vibration-part main surfaces. The recess is located at the holding-part side surfaces.