US-12628592-B2 - Substrate processing method

Abstract

Disclosed is a substrate processing method for selectively etching a re-growth silicon oxide formed on a surface of a silicon oxide layer and having a density lower than a density of the silicon oxide layer. The method includes: (a) placing a substrate including the re-growth silicon oxide into a reaction chamber; and (b) supplying an etching gas into the reaction chamber to dry-etch the re-growth silicon oxide formed on the surface of the silicon oxide layer, wherein the dry-etching is performed using HF and H 2 O as an etching gas at about 40° C. or lower.

Inventors

• Bongsoo KWON
• Dohyun Kim
• Yuri PARK

Assignees

• TES CO., LTD

Dates

Publication Date

20260512

Application Date

20241227

Priority Date

20241213

Claims (8)

1. 1 . A method for processing a substrate so as to selectively etch a re-growth silicon oxide formed on a surface of a silicon oxide layer and having a density lower than a density of the silicon oxide layer, the method comprising: (a) placing a substrate including the re-growth silicon oxide into a reaction chamber; and (b) supplying an etching gas into the reaction chamber to dry-etch the re-growth silicon oxide formed on the surface of the silicon oxide layer, wherein the dry-etching is performed using HF and H 2 O as an etching gas at about −10° C. to 10° C., at a process pressure of about 1.2 to 3.0 Torr, and at a HF flow rate of about 70 to 100 sccm.
2. 2 . The method for processing the substrate of claim 1 , wherein the (b) is performed at a H 2 O flow rate of about 50 to 300 sccm.
3. 3 . The method for processing the substrate of claim 1 , wherein the method further comprises, after the dry-etching, raising a temperature of the substrate to remove a reaction by-product.
4. 4 . The method for processing the substrate of claim 3 , wherein the dry-etching, the substrate temperature raising, and purging constitute a unit cycle, wherein the method further comprises performing a plurality of unit cycles.
5. 5 . A method for processing a substrate, the method comprising: (a) wet-etching a silicon nitride layer on a substrate having a stack formed thereon, using a phosphoric acid-based etchant, wherein the stack has a structure in which silicon oxide layers and silicon nitride layers are stacked on top of each other, wherein a re-growth silicon oxide is formed on a surface of the silicon oxide layer in the wet-etching; and (b) dry-etching the re-growth silicon oxide formed on the surface of the silicon oxide layer using an etching gas, wherein the (b) is performed using HF and H 2 O as the etching gas at about −10° C. to 10° C., at a process pressure of about 1.2 to 3.0 Torr, and at a HF flow rate of about 70 to 100 sccm.
6. 6 . The method for processing the substrate of claim 5 , wherein the (b) is performed at a H 2 O flow rate of about 50 to 300 sccm.
7. 7 . The method for processing the substrate of claim 5 , wherein the method further comprises, after the dry-etching, raising a temperature of the substrate to remove a reaction by-product.
8. 8 . The method for processing the substrate of claim 7 , wherein the dry-etching, the substrate temperature raising, and purging constitute a unit cycle, wherein the method further comprises performing a plurality of unit cycles.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application Nos. 10-2023-0193333 (filed on Dec. 27, 2023) and 10-2024-0185739 (filed on Dec. 13, 2024), which are all hereby incorporated by reference in their entirety. BACKGROUND The present disclosure relates to a substrate processing method. More specifically, the present disclosure relates to a substrate processing method capable of efficiently removing re-growth silicon oxide generated at a corner of a silicon oxide layer during wet-etching of a silicon nitride layer using a phosphoric acid-based etchant. Recently, as semiconductor devices are miniaturized, semiconductor devices are gradually becoming highly integrated. Since the silicon nitride film is used as a dielectric film or an insulating film having a chemically stable characteristic, the silicon nitride film is widely used in DRAM and FLASH Memory manufacturing processes, such as being used as a side wall material in a contact process or a capping process as well as a basic device isolation process of a memory device. In this regard, when manufacturing the semiconductor device, silicon oxide layers and silicon nitride layers may be alternately stacked on top of each other in multiple layers. In this case, in order to selectively etch the silicon nitride layers, an etchant having a higher etch selectivity relative to the silicon nitride layers than relative to the silicon oxide layer should be applied. Conventionally, a phosphoric acid-based etchant is known as the etchant having the higher etch selectivity relative to the silicon nitride layers than relative to the silicon oxide layer. The etching of the silicon nitride layer using the phosphoric acid-based etchant is wet-etching. It is known that the wet-etching of the silicon nitride layer using the phosphoric acid-based etchant involves a reaction according to a following reaction formula 1 and is performed at a high temperature. In this case, the regrowth silicon oxide generated at the corner portion of the silicon oxide layer during the wet-etching of the silicon nitride layer using the phosphoric acid-based etchant is problematic. The re-growth silicon oxide is known as a factor that affects a subsequent process and degrades electrical characteristics of a semiconductor device to be finally manufactured. In general, it is known that a silicon-based compound is contained as an additive in the phosphoric acid-based etchant to generate the re-growth silicon oxide. To solve this problem, it has been proposed that the regrowth silicon oxide itself is suppressed during wet-etching of the silicon nitride layer through adjustment of the additive contained in the phosphoric acid-based etchant. However, these methods have a disadvantage in that the wet-etching process time for etching the silicon nitride layer is very long. SUMMARY As described above, the conventional method of suppressing the generation of re-growth silicon oxide during wet-etching of the silicon nitride layer has a disadvantage in that the process time is very long. Accordingly, a purpose to be achieved by the present disclosure is to provide a substrate processing method capable of efficiently removing the re-growth silicon oxide using a separate dry-etching scheme, instead of suppressing the generation of the re-growth silicon oxide in the wet-etching of the silicon nitride layer. In addition, a purpose to be achieved by the present disclosure is to provide a substrate processing method capable of increasing an etch selectivity of a re-growth silicon oxide compared to that of an oxide formed via deposition or the like. Purposes according to the present disclosure are not limited to the above-mentioned purpose. Other purposes and advantages according to the present disclosure that are not mentioned may be understood based on following descriptions, and may be more clearly understood based on embodiments according to the present disclosure. Further, it will be easily understood that the purposes and advantages according to the present disclosure may be realized using means shown in the claims or combinations thereof. In order to achieve the purposes, a first aspect of the present disclosure provides a method for processing a substrate so as to selectively etch a re-growth silicon oxide formed on a surface of a silicon oxide layer and having a density lower than a density of the silicon oxide layer, the method comprising: (a) placing a substrate including the re-growth silicon oxide into a reaction chamber; and (b) supplying an etching gas into the reaction chamber to dry-etch the re-growth silicon oxide formed on the surface of the silicon oxide layer, wherein the dry-etching is performed using HF and H2O as an etching gas at about 40° C. or lower. In accordance with some embodiments of the method of the first aspect, the (b) is performed at a substrate temperature of about −10° C. to 20° C. In accordance with some embodiments of the method