Daily checking and calibrating method of length measuring machine

A daily checking and calibrating method of a length measuring machine, comprising:

• step (1) for detecting a state of the length measuring machine at a predetermined daily check time;
• step (2) for stopping transportation of substrates and the process goes to step (3) upon determining the length measuring machine is in an idle state, and for waiting until the length measuring machine transit to the idle state if the length measuring machine is in an operational state;
• step (3) for measuring coordinates of positioning marks on a substrate-carrying platform to generate a measured data file, and for comparing the measured coordinates of the positioning marks with predetermined standard coordinates;
• step (4) for automatically calculating a calibration value, updating the calibration value to a coordinate parameter file to complete automatic calibration, and automatically backing up the coordinate parameter file, and then the process goes to step (14) when a difference between the measured coordinates of the positioning marks and the predetermined standard coordinates is smaller than a predetermined value, and for activating an alarm and then the process goes to step (5) when the difference between the measured coordinates of the positioning marks and the standard coordinate is larger than the predetermined value;
• step (5) for determining follow-up measures when the difference between the measured coordinates of the positioning marks and the predetermined standard coordinates is larger than the predetermined value, the determination is made in accordance with a predicted reason causing the difference, and the follow-up measures comprises automatic calibration, no calibration, and additional measurements of large-scale substrate;
• step (6)—the process goes to step (7) upon choosing the automatic calibration, the process goes to step (13) upon determining not to apply the automatic calibration, and the process goes to step (8) upon choosing the additional measurement of the large-scale substrate;
• step (7) for automatically calculating the calibration value basing on the measured data file generated in step (3), updating the calibration value to the coordinate parameter file to complete the automatic calibration, and backing up the original coordinate parameter file and the process goes to step (14);
• step (8) for measuring the coordinates of confirmation marks of the large-scale substrate on the substrate-carrying platform to generate a substrate-measured-data file, and for comparing the measured coordinates of the confirmation marks and the predetermined confirmation coordinates;
• step (9) for automatically calculating the calibration value basing on the measured data file generated in step (3), updating the calibration value to the coordinate parameter file to complete the automatic calibration and the process goes to step (14), and automatically backing up the coordinate parameter file when the difference between the measured coordinate of the confirmation marks and the predetermined confirmation coordinate is smaller than the predetermined value, and for activating the alarm and the process goes to step (10) when the difference between the measured coordinates of the confirmation marks and the predetermined confirmation coordinates is larger than the predetermined value;
• step (10) for determining the follow-up measures when the difference between the measured coordinates of the confirmation marks and the predetermined confirmation coordinates is larger than the predetermined value, the determination is made in accordance with a predicted reason causing the difference, and the follow-up measures comprises applying automatic calibration or not to apply automatic calibration;
• step (11) for executing the automatic calibration and the process goes to step (12), and the process goes to step (13) when the follow-up measure is not to apply automatic calibration;
• step (12) for automatically calculating the calibration value basing on the measured data file generated in step (3), updating the calibration value to the coordinate parameter file to complete the automatic calibration, and backing up the original coordinate parameter and the process goes to step (14);
• step (13)—the process goes to step (14) upon determining not to apply the automatic calibration, and the process goes to step (15) upon determining the length measuring machine is in an abnormal operation state comprising components dislocations and abnormal temperature;
• step (14) for resuming a substrate-transportation function and the process ends;
• step (15) for notifying of the abnormal operation state of the length measuring machine, and the process ends;
• wherein the substrate-carrying platform comprises four cross-shaped positioning marks arranged at four corners, the length of the positioning marks is in the range of between 500 μm and 1000 μm, and the width of the positioning marks is in the range of between 20 μm and 50 m;
• wherein the positioning marks are directly formed on the substrate-carrying platform by jet printing or titler;
• wherein the positioning marks are formed by Cr or photoresist, and when the positioning marks are formed by the photoresist, a protective film is formed outside the positioning marks, and the protective film is made by ITO layer or Si layer;
• wherein a coordinate system of the substrate-carrying platform is established by the steps of:
• step (101) for respectively defining the four positioning marks as a first point, a second point, a third point, and a fourth point, the first point and the fourth point are arranged along diagonals of the substrate-carrying platform, the second point and the third point are arranged along diagonals of the substrate-carrying platform, and for measuring the coordinates of the four points;
• step (102) for calculating a middle point of the first point and the third point and labeling the middle point as “A”, and for calculating the middle point of the second point and the fourth point and labeling the middle point as “B”;
• step (103) for calculating the middle point of the point “A” and the point “B” and labeling the middle point as “O”;
• and
• step (104) for defining the point “O” as an origin, the direction from the third point toward the first point is the positive direction of the Y axis, and the direction from the third point toward the fourth point is the positive direction of the X axis to establish the coordinate system of the substrate-carrying platform;
• wherein standard coordinates of the first point, the second point, the third point, and the fourth point are represented as (X1, Y1), (X2, Y2), (X3, Y3) and (X4, Y4), and measured coordinates of the first point, the second point, the third point, and the fourth point are represented as (X′1, Y′1), (X′2, Y′2), (X′3, Y′3), and (X′4, Y′4), the calibration values are calculated by:
• ΔX(The calibration value in the X axis)=[(X′1−X1+X′4−X4)/2−(X′2−X2+X′3−X3)/2]/2;
• ΔY(The calibration value in the Y axis)=[(Y′3−Y3+Y′4−Y4)/2−(Y′1−Y1+Y′2−Y2)/2]/2;
• and
• Δθ(The calibration value in the orthogonal axis)=[(X′3−X3+X′4−X4)/2−(X′1−X1+X′2−X2)/2]/2;
• wherein the step (8) further comprises transporting the large-scale substrates from a constant-temperature buffer to the substrate-carrying platform by a robot, and transporting the large-scale substrates from the substrate-carrying platform to the constant-temperature buffer by the robot after the measurement is completed;
• wherein the measured data files generated in step (3) are named by date information;
• and
• wherein the length measuring machine is a TFT-LCD length measuring machine for measuring a total pitch of exposure machines while manufacturing a first layer patterns of thin film transistor (TFT) substrate or color filtering (CF) substrates.