Ultra-thick epitaxial wafer for high-voltage power device and manufacturing method thereof

Abstract

The invention discloses an extremely thick epitaxial wafer for high-voltage power devices. The extremely thick epitaxial wafer comprises a substrate and an epitaxial layer, and is characterized in that the substrate is more than 6 inches, and the thickness of the epitaxial layer is more than 100 [mu]m. The extremely thick epitaxial wafer and the method for manufacturing the same effectively solve problems that after epitaxy, a large-sized extremely thick epitaxial wafer gets broken, has edge impression trails and large detects in crystal growth and has poor thickness uniformity and resistance rate uniformity during a large-scale industrial continuous production process, and satisfy requirements of epitaxial wafer edges and wafer surfaces after design of devices. Furthermore, the related extremely thick epitaxial wafer can be widely applied to high-voltage power devices, and can bear a high voltage up to 1,900V which is a breakthrough for the first time at home. According to the extremely thick epitaxial wafer which is produced by using the manufacture method and is used for high-voltage power devices, the thickness non-uniformity can be reduced to 2.03% and the resistance rate non-uniformity can be reduced to 4.24%.

Description

technical field [0001] The invention relates to an extremely thick epitaxial wafer for a high-voltage power device and a manufacturing method thereof. Background technique [0002] Epitaxy is the process of growing a silicon single crystal thin film on the silicon single crystal substrate along the original crystal direction. Silicon epitaxial wafer is the main material for making semiconductor discrete devices, because it can not only ensure the high breakdown voltage of PN junction, but also reduce the forward voltage drop of the device. Some high-voltage power devices have a withstand voltage requirement of 1500V or even higher. Correspondingly, the epitaxial thickness requirement has reached more than 100um, or even 160um. [0003] There are three important parameters to measure the quality of epitaxy, namely thickness, resistivity, and surface defects. With the increase of epitaxial thickness, especially for large-scale epitaxial wafers such as 6 inches or more, the t...

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Problems solved by technology

With the increase of epitaxial thickness, especially for large-scale epitaxial wafers such as 6 inches or more, the thickness of the epitaxial layer and the uniformity of resistance value will become difficult to adjust, and it is even more difficult to achieve a perfect wafer surface

[0004] With such a thick epitaxy on a 6-inch or 8-inch epitaxy, the epitaxial wafer manufactured according to the traditional process and related equipment and material configuration has the following defects: 1. Fragments or lobes, the epitaxial layer can be regarded as a layer A layer of extremely thin film is accumulated and stacked on the substrate, which will bend under the action of external force, and the temperature of each point of the wafer will have greater and greater differences with the increase of the epitaxial thickness. When the temperature of different positions of the same wafer When the gradient reaches a certain level, cracking will occur; 2. The thickness uniformity and resistivity uniformity are poor. A large number of test data have been obtained. Under the condition of other conditions unchanged, the thickness of the grown crystal changes from 40um to more than 100um. The thickness uniformity changed from 2% to 6%, and the resistivity uniformity changed from 3% to 8% or even worse. The deposition rate of various chemical components of the point is inconsistent; the calculation formula: thickness / resistivity non-uniformity=(MAX-MIN)*100% / (MAX+MIN), MAX is the maximum thickness / Resistivity value, MIN is the minimum thickness / resistivity value among 9 points

3. The crystal growth defects on the surface, especially the crystal growth defects at the edge of the wafer, due to the looser arrangement of atoms and molecules in the epitaxy compared with the substrate, show that the physical properties are not as hard as the substrate. With the continuous increase of the epitaxial layer Thick, edge defects will increase, especially this kind of extremely thick epitaxy greater than 100um, will grow large-size (>0.5um) defects formed by long crystals such as hillocks and stacking faults on the edge; 4. The edge of the wafer is epitaxial Extending the indentation of the mechanical arm of the crystal furnace table, this is because the extremely thick epitaxy has very high requirements for the adjustment of the equipment, especially when the mechanical arm puts in and takes out the wafer due to the huge difference in thickness before and after the wafer grows and the use of crystal growth. The indentation of the edge of the wafer after the arm is epitaxially caused by the unreasonable size of the graphite pit

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