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Film is reflected in the quality of the film surface without spots, hair flower and pinhole defects such as cracks, white mist. Reach regulation index and maintain uniform thickness. Moving the impurity ions in the membrane, especially the content of sodium ion also must be a clear request. 

1, The colorimetric method

Direct observation of silicon oxide film color, can be more convenient to estimate the thickness of oxide film. Since light interference effect, different thickness of silicon dioxide film show different color.

(1)The color of the oxide film thickness increases with its cyclical changes.

(2)Corresponds to the same color, there may be several thickness, the error of this approach is large.

(3)However, you can grow a silicon dioxide wafer is etched in hydrofluoric acid, observe the color changes to determine its thickness.

(4)When the thickness is 7500 Angstroms, the color change is not obvious. Therefore, this method is only applicable to oxide thickness

(5)Degree in one micron or less.

The most common method is the interference method, the equipment is simple, easy to measure, but also more accurate. Has been oxidized silicon surface flies, wax or a certain area vacuum grease protection (such as silicon area accounts for 1/2 --- 1/3), and then placed in hydrofluoric acid, the unprotected oxide film etched, and finally with an organic solution (such as toluene, carbon tetrachloride) or vacuum wax oil addition to the net, which is the emergence of silicon dioxide slope.



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