A documentation sample

Here is the introduction to some documentation that I once wrote. The formatting is awry because I cut and paste this from the original Word file, and some of the formatting (the table, in particular) was lost.

Wafer transfers are done through the use of stations – that is, user-specified locations at which the wafers are to be picked or placed. These stations can be wafer cassettes, prealigner chucks, or any other location where a wafer might normally reside. Each station is identified by the following set of parameters which determine where and how the wafer is to be picked up or set down, and how the robot should scan for their presence.


Station Parameters
Radial (mm) The radial position (i.e. the R-axis position) at which the robot would pick up the wafer or set it down.
Theta (deg) The rotational angle (i.e. the -axis position) at which the robot would pick up the wafer or set it down.
Z (mm) The height (i.e. the Z-axis position) at which the robot would enter the station to set down the bottommost wafer. Equivalently, this is also the height at which it would retract from the station when picking up the bottommost wafer.
Z offset (mm) A parameter used by the pick/place routines for certain end-effectors. When using the ROB310 vacuum gripper, its value should be set to zero.
Pitch (mm) The vertical distance between consecutive wafers in a multi-slot station. This distance is measured between the bottom surfaces of each wafer.
Stroke (mm) The vertical distance that the robot moves when the arm is extended and picking or placing the wafer. Its value should be less than that of the pitch.
Retract (mm) The R-axis position to which the robot should retract after grasping a wafer. This is also the position to which the R-axis would retract before rotating to the station for a pick or place move.
End-effector option An integer designating the end-effector to be used (typically 0 or 1).
Slots The number of slots at the station in question.
Pick/Place Vel (mm/s) The maximum velocity to be used during the vertical stroke, when picking or placing a wafer.
Pick/Place Accel (mm/s2) The maximum acceleration to be used during the vertical stroke, when picking or placing a wafer.
Radial per Slot (mm) A parameter for compensating for stations that are tilted from the vertical axis. In most situations, this should be set to zero.
Scan Radial (mm) The R-axis position to be used for scanning the wafers. This value should be selected so as to place the wafer mapping sensor at an optimal distance from the wafers.
Scan Z (mm) The height at which the robot begins its upward scan movement
Scan Velocity (mm/s) The maximum vertical velocity to be used when scanning a station.
Scan Acceleration (mm/s2) The vertical acceleration limit to be used when scanning a station.
Scan Radial Offset (mm) A parameter which allows the robot to use two different radial positions for the upward and downward scans. This value should typically be set to zero.
Scan Theta Offset (deg) A parameter which permits two different rotational positions to be used for the upward and downward scans. This should typically be non-zero.
Scan Above (% of pitch) One of the parameters used for identifying cross-slotted wafers
Scan Below (% of pitch) One of the parameters used for identifying cross-slotted wafers
Scan Thick (% of pitch) A parameter used for identifying double- and cross-slotted wafers