Method for forming a thick bottom oxide (tbo) in a trench mosfet

A trench type, trench technology, applied in electrical components, semiconductor/solid-state device manufacturing, semiconductor devices, etc., can solve the problems of increasing heat, not suitable for trench aspect ratio, etc., and achieve the effect of low thermal budget

Inactive Publication Date: 2011-04-13
CHENGDU MONOLITHIC POWER SYST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The disadvantage is that this method increases the heat required for the process and is not suitable for trench MOSFETs with large aspect ratios

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  • Method for forming a thick bottom oxide (tbo) in a trench mosfet
  • Method for forming a thick bottom oxide (tbo) in a trench mosfet
  • Method for forming a thick bottom oxide (tbo) in a trench mosfet

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Embodiment Construction

[0015] The specific embodiments described in the document represent exemplary embodiments of the invention and are merely illustrative in nature and not limiting. Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. The appearances of the phrase "in one embodiment" in various places in the specification are not all referring to the same embodiment, nor are they intended to mutually exclude other or alternative embodiments.

[0016] The invention discloses a method for forming thick oxygen at the bottom of a vertical trench type MOSFET trench. Initially, an n-type epitaxial layer is grown on an n-type silicon substrate. P-type dopant is injected into the top region of the n-type epitaxial layer to form a p-type doped layer. A groove is etched in the p-type doped layer and the n-type epitaxial...

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Abstract

A method for forming a thick bottom oxide in the bottom of a trench used in a vertical MOSFET. Initially, an n-type substrate has an n-type epitaxial layer grown thereon. A top portion of the n-type epitaxial layer is implanted with p-type dopants to provide a p-layer. A trench is then etched into the p- and n-type epitaxial layer. A high density plasma chemical vapor deposition (HDPCVD) process is used to either partially or fully fill the trench. Any oxide on the top surface of the p-layer is then removed, such as by using a chemical mechanical polishing step. Then, an isotropic etching step, such as a wet etch, is used to remove the silicon dioxide from the trench, while leaving a thick bottom oxide at the bottom of the trench. The HDPCVD process utilizes minimal thermal budget to form the thick bottom oxide.

Description

technical field [0001] The present invention relates to a vertical trench MOSFET (Vertical Trench MOSFET), and more specifically, the present invention relates to a method for forming thick bottom oxide (TBO) at the bottom of a trench of a vertical trench MOSFET. Background technique [0002] Vertical trench MOSFET has the advantages of high integration density, high current capability, low on-resistance and excellent turn-off characteristics. Due to the above size and performance advantages, the vertical trench power MOSFET has been widely used rapidly. The current of the vertical type trench MOSFET flows through the substrate in the vertical direction, and the gate is located in the trench of the semiconductor substrate and is usually formed by filling polysilicon. [0003] It is well known that forming a bottom thick oxygen at the bottom of the trench has multiple advantages, which can increase the breakdown voltage and reduce the capacitance between the gate and the dra...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L21/28H01L21/285H01L29/40H01L29/78
CPCH01L29/42368H01L29/66734H01L29/7813
Inventor 李铁生
Owner CHENGDU MONOLITHIC POWER SYST
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