The invention refers to a disposable sample holding and processing device (1) for being used in an apparatus for analyzing a liquid sample by nucleic acid amplification, especially polymerase chain reaction technique, comprising a device body (2) having a structured surface and a sealing cover (4) which covers the structured surface thereby forming a wall of an amplification chamber (5)), which amplification chamber (5) is designed and intended for performing nucleic acid amplification for analyzing the liquid sample, and a wall of an inlet channel (6) connected to the amplification chamber (5) for providing the amplification chamber (5) with liquid. According to the invention the device body (2) comprises a sheet (20) on which the structured surface forming the inlet channel (6) is arranged, and that the sheet (20) carries at least one rib (34, 35, 36) for increasing the stiffness of the device body (2).