CN-121985550-A - HEMT device passivation layer etching method and HEMT device

CN121985550ACN 121985550 ACN121985550 ACN 121985550ACN-121985550-A

Abstract

The embodiment of the application discloses a passivation layer etching method of an HEMT device and the HEMT device, wherein the method comprises the steps of providing a functional layer with a passivation layer; forming a passivation layer on the surface of the functional layer, forming a sacrificial layer on the surface of the passivation layer, forming an opening on the surface of the sacrificial layer, performing plasma dry etching on the surface of the passivation layer exposed in the opening at a first temperature which is gradually increased to form a first etching structure with the bottom positioned in the passivation layer, performing plasma dry etching of a default mask on the sacrificial layer at a second temperature which is continuously gradually increased to remove all the sacrificial layer, performing chemical dry etching of the default mask on the surface of the passivation layer and the first etching structure at a third temperature which is continuously gradually increased to form a second etching structure with the bottom positioned on the surface of the functional layer on the etched surface of the passivation layer, and completing annealing by using the third temperature. The application can effectively reduce etching damage and maintain etching morphology.

Inventors

ZHU RONGFENG
WANG ZHAOXIANG
XU BING
WANG XIAOWEN
LIANG JIE

Assignees

上海邦芯半导体科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260403

Claims (10)

1. The passivation layer etching method of the HEMT device is characterized by comprising the following steps of: providing a functional layer with a passivation layer on the surface; forming a sacrificial layer on the surface of the passivation layer, and forming an opening on the surface of the sacrificial layer; Performing first etching on the exposed surface of the passivation layer at a first temperature through the opening by using a first etching process, and forming a first etching structure on the surface of the passivation layer, wherein the distance between the bottom of the first etching structure and the surface of the functional layer is greater than zero; Performing a second etching process at a second temperature on the sacrificial layer by using a second etching process of a default mask, and removing the sacrificial layer to expose the first etching structure and all surfaces of the passivation layer around the first etching structure; performing a third etching process at a third temperature on the surface of the passivation layer and the first etching structure by using a default mask, so that the surface of the passivation layer and the first etching structure are conformally pushed towards the surface direction of the functional layer until a second etching structure changed from the first etching structure is formed on the etched surface of the passivation layer, and the surface of the functional layer positioned on the bottom of the second etching structure is exposed; The first etching process and the second etching process comprise a plasma dry etching process, the third etching process comprises a chemical dry etching process, and the first temperature, the second temperature and the third temperature are gradually increased and sequentially connected variable temperature.
2. The method for etching the passivation layer of the HEMT device according to claim 1, wherein when the third etching is performed, the exposed surface of the functional layer is further subjected to a first treatment at the third temperature to repair surface lattice damage.
3. The method for etching the passivation layer of the HEMT device according to claim 1, wherein during the third etching, O 2 is added into the etching gas, and the exposed surface of the functional layer is subjected to a second treatment to reduce the surface roughness.
4. The method for etching the passivation layer of the HEMT device according to claim 1, further comprising adding N 2 to an etching gas during the third etching, and performing a third treatment on the exposed surface of the functional layer to stabilize the surface stoichiometry.
5. The method according to claim 1, further comprising performing a fourth process on the exposed surface of the functional layer by using hydrogen radicals after the third etching, so as to clean the surface.
6. The method according to claim 1, wherein the functional layer comprises a GaN layer or an AlGaN layer, and/or the passivation layer comprises a dielectric layer, and/or the sacrificial layer comprises an organic layer.
7. The method for etching the passivation layer of the HEMT device according to claim 1, wherein first etching is performed by using first plasma obtained by exciting first gas, the first gas comprises first fluorine-based gas, second etching is performed by using second plasma obtained by exciting second gas, the second gas comprises oxygen-based gas, third etching is performed by using third plasma obtained by exciting third gas, neutral particles obtained after charged particles in the third plasma are filtered, and the third etching is performed by using third plasma obtained by exciting second gas, the third gas comprises second fluorine-based gas.
8. The method according to claim 7, wherein the first fluorine-based gas comprises CF 4 and CHF 3 , and/or the oxygen-based gas comprises O 2 , and/or the second fluorine-based gas comprises CF 4 , and/or the distance is 10% -20% of the thickness of the passivation layer.
9. The method according to claim 1, wherein the first temperature is a first temperature varying temperature gradually increasing between 0 ℃ and 150 ℃, and/or the second temperature is a second temperature varying temperature gradually increasing between 100 ℃ and 250 ℃, and/or the third temperature is a third temperature varying temperature gradually increasing between 200 ℃ and 300 ℃.
10. A HEMT device comprising a passivation layer, wherein the passivation layer is etched using a passivation layer etching method of the HEMT device of any one of claims 1-9.

Description

HEMT device passivation layer etching method and HEMT device Technical Field The application relates to the technical field of semiconductor processing, in particular to a passivation layer etching method of an HEMT device and the HEMT device. Background In the fabrication of gallium nitride HEMT (high electron mobility transistor) devices, it is often necessary to deposit a surface passivation layer for suppressing the current collapse effect. In both ohmic contact and gate trench fabrication, it is necessary to first open the passivation layer by etching and then deposit the metal. The passivation layer is etched by plasma etching, so that the etching uniformity and the etching angle of the side wall can be controlled conveniently, and the etching efficiency is improved. But the bottom GaN or AlGaN layer can be touched in the etching process, and if the etching damage to the GaN or AlGaN layer is larger at this time, the two-dimensional electron gas is influenced, so that the device performance can be obviously reduced. Etching damage may include lattice damage, surface roughening, stoichiometric deviation, surface contamination, etc., mainly caused by bombardment and chemical reaction of energetic ions and reactive radicals in the plasma to the GaN lattice. Therefore, it is necessary to develop a process method capable of significantly improving the etching damage of the underlying layer. Disclosure of Invention The application aims to overcome the problems in the prior art and provides a passivation layer etching method of an HEMT device and the HEMT device. In order to achieve the above purpose, the technical scheme of the application is as follows: According to a first aspect of the present application, an embodiment of the present application provides a passivation layer etching method of a HEMT device, including: providing a functional layer with a passivation layer on the surface; forming a sacrificial layer on the surface of the passivation layer, and forming an opening on the surface of the sacrificial layer; Performing first etching on the exposed surface of the passivation layer at a first temperature through the opening by using a first etching process, and forming a first etching structure on the surface of the passivation layer, wherein the distance between the bottom of the first etching structure and the surface of the functional layer is greater than zero; Performing a second etching process at a second temperature on the sacrificial layer by using a second etching process of a default mask, and removing the sacrificial layer to expose the first etching structure and all surfaces of the passivation layer around the first etching structure; performing a third etching process at a third temperature on the surface of the passivation layer and the first etching structure by using a default mask, so that the surface of the passivation layer and the first etching structure are conformally pushed towards the surface direction of the functional layer until a second etching structure changed from the first etching structure is formed on the etched surface of the passivation layer, and the surface of the functional layer positioned on the bottom of the second etching structure is exposed; The first etching process and the second etching process comprise a plasma dry etching process, the third etching process comprises a chemical dry etching process, and the first temperature, the second temperature and the third temperature are gradually increased and sequentially connected variable temperature. In some embodiments, when the third etching is performed, the exposed surface of the functional layer is further subjected to a first treatment at the third temperature, so as to repair surface lattice damage. In some embodiments, when the third etching is performed, O 2 is further added to the etching gas, so as to perform a second treatment on the exposed surface of the functional layer, so as to reduce the surface roughness. In some embodiments, when the third etching is performed, the exposed surface of the functional layer is further subjected to a third treatment by adding N 2 to the etching gas, so as to stabilize the surface stoichiometry. In some embodiments, the method further comprises performing a fourth treatment on the exposed surface of the functional layer using hydrogen radicals after performing the third etching to perform surface cleaning. In some embodiments, the functional layer comprises a GaN layer or an AlGaN layer. In some embodiments, the passivation layer comprises a dielectric layer. In some embodiments, the sacrificial layer comprises an organic layer. In some embodiments, the first etching is performed using a first plasma resulting from exciting a first gas, the first gas comprising a first fluorine-based gas. In some embodiments, the second etching is performed using a second plasma resulting from exciting a second gas, the second gas comprising an oxygen-based gas. In some e