The Ellipsometry calculator uses the P1, A1, P2, and A2 angles found using an ellipsometer to calculate delta, psi, index and thickness. It works for thicknesses greater than or equal to 50 nm and less than 250 nm. It can calculate indexes ranging from 1.3 to 2.11. Below is also a "Time and Rate Calculator" that uses the thickness calculated from the Ellipsometry calculator along with the test wafer growth time and desired thickness to calculate the rate of growth and the time needed to grow the desired thickness at that rate.
To use the Ellipsometry Calculator: - Select the angle of incidence of the ellipsometer. - Choose an estimated range for the thickness of your layer. If the wrong range is selected then the results will be wrong. - Enter the values found for P1 and A1. - P2 and A2 are optional, but the result will be more accurate if you enter these in also. - Click "Calculate" - The values for delta, psi, index, and thickness will appear.
To use the Time/Rate Calculator: - Make sure the correct thickness is in the thickness field of the Ellipsometry Calculator. - Enter the "Test Wafer Growth Time" minutes and seconds. (There is more than one way you can enter these. For example, if you grew 2 minutes and 30 seconds you could enter those same numbers in the corresponding fields or you could enter '2.5' in the minutes field and '0' in the seconds field.) - Enter the "Desired Thickness" of the layer you want to grow or you can leave this blank if you only need the rate. - Click "Calculate Time"
The Ellipsometry Calculator uses the values P1, A1, P2, and A2 to calculate delta and psi. If the numbers input for these values are out of range or non-numeric characters are included then the calculator will not be able to calculate delta and psi. After finding delta and psi the ellipsometry calculator searches through multiple look up tables (LUTs) comparing the values of delta and psi to those in the table. When it finds the entry closest in value to delta and psi it can use that same entry number to find the corresponding index and thickness in other LUTs. Different LUTs are used depending on the chosen angle of incidence. The thickness range is necessary because on some materials like silicon nitride there may be two possible thicknesses the calculator could return based on its search and compare algorithm. After finding the right index the ellipsometry calculator then searches through the thickness range selected using the same method described above with delta and psi. It is common for the calculator to be off by one in the least significant decimal place such as a thousandth on the index or a tenth of a nanometer on the thickness. It is very rare for the calculator to be off by more than this, but it can occur so if high accuracy is needed then results should be double checked with another program. Please note that the ellipsometry calculator can only work for thicknesses between 50 nm and 250 nm and indexes between 1.3 and 2.11. If your result seems to be on the upper or lower of these bounds then it might be out of the range of the calculator.