a micropump for pumping liquid from an entry channel to an exit channel is disclosed . the micropump is formed in a semiconductor substrate sealed by two glass substrates . the micropump includes first and second chambers and flow channel means coupled between the two chambers . the micropump also includes a valve coupled between the entry channel and the first chamber . the valve includes a flexible valve membrane positioned closer to a second side of the semiconductor substrate than to its first side for causing the valve to be or not to be in contact with the second side of the semiconductor substrate for closing or opening the valve on the glass substrate . additionally , the micropump includes a diaphragm forming part of a flexible wall of the second chamber and positioned closer to the second side of the semiconductor substrate than to its first side . the diaphragm is responsive to external pressure for causing liquid to be pumped from the entry channel to the exit channel . thus , the height of the valve is reduced , preventing deformation due to strength such as its own weight and may impact due to a dropping . as a result , the valve sealing is improve on the glass substrate . therefore , the micropump can accurately discharge a small quantity of liquid .