"Wafer bonding" is a process for creating devices by bonding together two (or more) wafers or substrates. In recent years the main method for doing this has been thermobonding. In this method, the precision of contact bonding is highly dependent on the applied pressure. Even with MEMS, if the pressure applied to bond the wafers or substrates is not constant, problems such as "defective sealing," "uneven bonding strength," and "pattern width unevenness" may occur.