Method for evaluating shape of wafer, wafer and method for selecting wafer
An evaluation method and wafer technology, which can be applied to measurement devices, instruments, electrical components, etc., and can solve problems such as inability to be accurately evaluated.
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Embodiment 1
[0097] An example related to the shape evaluation method of the present invention will be described. In this example, an 8-inch specular wafer (a wafer with a diameter of 200 mm and a chamfered portion with an outer circumference of 0.5 mm) manufactured by a general manufacturing process was evaluated. This wafer is referred to as S1.
[0098] Shape evaluation is to measure the entire surface of the wafer (excluding the outer periphery of the chamfered portion 0.5mm) at intervals of 0.95 mm, and sequentially memorize the thickness of the wafer measured above, and obtain the following shape from the memorized shape. figure 1 The profile (shape) from the center of the wafer to the edge (98.5 mm from the center) is shown, and the distance from the center (diametrically) to any position X (70 mm from the center, 98.5 mm from the edge) is used. 30mm), calculate the reference line by the least square method, then analyze the difference between the thickness at any position and the ...
Embodiment 2
[0109] In order to confirm the above findings, wafers manufactured in a plurality of wafer processing steps were evaluated by the above-mentioned shape evaluation method. Specifically, the wafer is manufactured by changing the wafer processing process so that the uniformity value of the outer peripheral portion of the B parameter can be reduced.
[0110] The wafer processing process is a slicing process that generally uses a wire saw to slice a single crystal ingot to obtain a thin disc-shaped wafer; in order to prevent cracks and gaps in the wafer obtained by the slicing process, its outer periphery is chamfered Partially used chamfering process; planarization process of lapping, surface wheel grinding, etc. to flatten the wafer; etching process for removing processing distortion left (residue) on the chamfered and planarized wafer; A polishing process for making the surface of the wafer mirror-like; and a cleaning process for cleaning the polished wafer to remove polishing a...
Embodiment 3
[0131] Even in the wafer processing shown in the example, the uniformity of the B parameter cannot be completely made below 600 nm. Therefore, wafers are evaluated by the shape evaluation method of the present invention, and after selecting wafers falling within the scope of the present invention, they are placed in a device process to implement a manufacturing process. Specifically, a wafer whose surface characteristic B has a uniformity of 600 nm or less in the peripheral portion of the wafer [these are surface characteristics (A-B) of which the uniformity of the peripheral portion of the wafer is 400 nm or less] is placed in a stepper process, and the device is observed Actions. As a result, it was confirmed that the stop of the device did not occur at all.
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