Vacuum robot positioning system with reduced sensitivity to chamber pressure

An apparatus comprising:

• a support structure for mounting a vacuum robot arm to a horizontally elongate vacuum transfer module for a semiconductor processing tool, the support structure including:
• a first set of one or more vacuum transfer module mount points collectively having a first centroid;
• a second set of one or more vacuum transfer module mount points collectively having a second centroid;
• and
• a set of one or more robot base mount points configured to connect the support structure with a base of the vacuum robot arm such that a rotational axis of a rotational joint in the base of the vacuum robot arm that connects the base with an arm segment of the vacuum robot arm is interposed between the first centroid and the second centroid, wherein:
• a first distance between the first centroid and the second centroid when viewed along the rotational axis is at least 70% of a horizontal width of the horizontally elongate vacuum transfer module along the short axis of the horizontally elongate vacuum transfer module, and
• a second distance between the first centroid and the rotational axis when viewed along the rotational axis is, when the support structure is connected with the base of the vacuum robot arm, at most 25% of the horizontal width of the vacuum transfer module along the short axis of the horizontally elongate vacuum transfer module.