Semiconductor processing apparatuses

A semiconductor processing apparatus comprising:

• a support member comprising an upper surface for supporting a semiconductor wafer;
• the support member being joined to a base;
• a component through which the support member extends, the component comprising a front surface and a back surface, the support member being movable relative to the component such that the support member can support a wafer in an elevated position above the front surface and can be withdrawn into the component to lower the wafer relative to the front surface of the component;
• the base being configured to move with the support member as the support member moves relative to the component;
• and
• an adjustable threaded member joined to the base below the component back surface, the adjustable threaded member moving with the support member and physically contacting the component back surface when the support member upper surface extends above the component to a predetermined distance, the adjustable threaded member preventing the support member upper surface from extending beyond the front surface by more than the predetermined distance.