▎ 摘　　要

NOVELTY - The device (100) has a device unit provided with a chamber upper wall (104) and a chamber lower wall (105). The chamber lower wall is mounted with a reaction chamber. A metal cavity wall (108) is fixed between the chamber upper wall and the chamber lower wall. The metal cavity wall is arranged around a periphery of the reaction cavity. The metal cavity wall is configured for shrinking or expanding around the reaction cavity. The metal cavity wall comprises a first end head and a second end head (1085). USE - 915 MHz microwave plasma chemical vapor deposition (MPCVD) device for preparing diamond material use in semiconductor industry. ADVANTAGE - The device can adjust diameter of the resonant cavity, quickly and conveniently realize microwave electromagnetic field tuning and plasma state adjustment and convenient and quick tuning the distribution and density of plasma in the reaction cavity, improves the electromagnetic field coupling effect and the growth efficiency of the diamond film. The device can prepare single crystal and polycrystalline diamond, carbon graphene, for semiconductor, cutter, optical window and heat sink. The first bent metal sheet reduces the gap between the second end head of the metal cavity wall and the first end head, and prevents the microwave leakage of the cavity. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a microwave plasma chemical vapor deposition device. 100Microwave plasma chemical vapor deposition device 101Microwave inlet 104Chamber upper wall 105Chamber lower wall 108Metal cavity wall 1085Second end