A verification method for dry capacity of a wet etching machine

Abstract

The application provides a kind of verification method of wet etching machine dry capacity, including providing wafer with side notch structure, the side notch structure is formed by depositing ONO layer on the surface of bare wafer, then trench etching is carried out, ONO layer includes bottom layer HTO layer, middle layer SiN layer and top layer TEOS layer;Wafer is etched by wet etching machine to remove oxide layer;The surface of bare wafer is subjected to thermal oxidation treatment to form sacrificial oxide layer;SiN layer and sacrificial oxide layer are removed;Wafer is measured and scanned by scanning machine for yield, if the defect scanning result is pit defect, the verification fails, otherwise, the verification passes.The application uses side notch structure wafer, and water mark is easy to produce in the gap of insufficient drying, pit defect is generated after oxide growth and removal process, using side notch structure wafer, after furnace tube thermal oxidation growth and oxide layer removal, the dry capacity of the machine is verified by defect result, the monitoring of wet etching machine dry capacity is improved, and the device yield is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a method for verifying the drying capability of a wet etching machine. Background Technology

[0002] The FC3100 (DNS) wet etching machine is widely used in fab production, primarily for pre-furnace tube cleaning and oxide film etching. The machine employs LPD (low-pressure drying) technology, providing a high concentration of IPA without carrier nitrogen gas to significantly suppress watermarks.

[0003] Existing DNS servers typically use optical wafers to monitor their drying capabilities, such as... Figure 1 As shown. However, this method cannot meet the drying capacity requirements of superjunction structure products. The superjunction structure is composed of alternating N-type pillars and P-type pillars. In trench etching, if the drying capacity of the WET machine is insufficient, it will affect the density of the subsequent oxide film, resulting in pore defects during oxide film etching and affecting the final product yield. Summary of the Invention

[0004] In view of this, the present invention provides a method for verifying the drying capability of a wet etching (WET) machine, thereby improving the monitoring of WET drying capability and increasing device yield.

[0005] This invention provides a method for verifying the drying capability of a wet etching machine, comprising the following steps:

[0006] Step 1: Provide a wafer with a side-hole structure, wherein the side-hole structure is formed by depositing an ONO layer on the surface of the bare wafer and then performing trench etching. The ONO layer includes a bottom HTO layer, an intermediate SiN layer and a top TEOS layer.

[0007] Step 2: Use a wet etching machine to perform wet etching on the wafer to remove the oxide layer;

[0008] Step 3: Perform thermal oxidation treatment on the surface of the bare wafer to form a sacrificial oxide layer;

[0009] Step 4: Etch away the SiN layer and the sacrificial oxide layer;

[0010] Step 5: Use a scanning machine to perform yield measurement and defect scanning on the wafer. If the defect scanning result is a pit defect, the verification fails; otherwise, the verification passes.

[0011] Preferably, the material of the wafer in step one is silicon.

[0012] Preferably, the ONO layer in step one is formed by sequential deposition using a low-pressure chemical vapor deposition method.

[0013] Preferably, the trench etching in step one is dry etching.

[0014] Preferably, the oxide layer removed in step two includes the top TEOS layer and the exposed portion of the HTO layer on the side.

[0015] Preferably, the thermal oxidation treatment in step three is furnace tube thermal oxidation growth.

[0016] Preferably, the etching in step four includes dry etching and wet etching processes.

[0017] This invention uses a side-drilled wafer structure. Insufficient drying can easily cause watermarks in the gaps. During the oxide growth and removal process, pit defects are generated. By monitoring these defects through yield measurement, the drying capacity of the machine can be monitored. Attached Figure Description

[0018] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0019] Figure 1 This diagram illustrates the existing DNS equipment verification method for drying capabilities.

[0020] Figure 2 The flowchart shown is a method for verifying the drying capability of a wet etching machine according to an embodiment of the present invention;

[0021] Figure 3 The diagram shown is a schematic representation of the side-hole structure wafer according to an embodiment of the present invention.

[0022] Figure 4 The diagram shows a side-cut structure wafer of an embodiment of the present invention being etched by a wet etching machine, resulting in watermarks due to insufficient drying;

[0023] Figure 5 The diagram shows a schematic representation of a side-hole structure wafer with pitting defects according to an embodiment of the present invention.

[0024] Figure 6 and Figure 7 The image shown is a wafer diagram and SEM image of a side-hole structure wafer with pit defects according to an embodiment of the present invention.

[0025] Figure 8 and Figure 9 The images shown are wafer images and SEM images of a side-hole structure wafer without pit defects, as shown in an embodiment of the present invention. Detailed Implementation

[0026] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0027] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0028] Unless the context explicitly requires it, words such as "including" or "contains" throughout the application should be interpreted as including rather than exclusive or exhaustive; that is, meaning "including but not limited to".

[0029] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] Figure 2 The flowchart shown is a method for verifying the drying capability of a wet etching machine according to an embodiment of the present invention. Figure 2 As shown, the method for verifying the drying capability of a wet etching machine according to an embodiment of the present invention includes the following steps:

[0031] Step 1: Provide a wafer with a side-cut structure. The side-cut structure is formed by depositing an ONO layer on the surface of the bare wafer and then performing trench etching. The ONO layer includes a bottom HTO layer, an intermediate SiN layer, and a top TEOS layer.

[0032] The wafer material can be silicon, germanium, silicon-germanium, or silicon carbide, or it can be silicon-on-insulator (SOI) or germanium-on-insulator (GOI), or other materials such as gallium arsenide or other group III and V compounds. In this embodiment, the wafer material is silicon (Si).

[0033] In existing manufacturing processes for ONO layers, the bottom silicon dioxide is generally deposited using thermal growth (consuming a silicon substrate) or LPCVD (low-pressure chemical vapor deposition) deposition (not consuming a silicon substrate). This typically includes furnace tube thermal oxidation, nitrogen doping, and thermal annealing. The silicon dioxide surface is improved by introducing Si-N bonds through ion implantation and thermal annealing, or by high-temperature nitriding of the surface silicon dioxide in a furnace tube followed by thermal annealing, thereby increasing the reliability of the silicon dioxide and its bonding strength with silicon nitride. The sandwich silicon nitride is generally deposited using furnace tube LPCVD deposition. To obtain better uniformity and controllability of the sandwich silicon nitride, a low-temperature silicon nitride process is often used, followed by a high-temperature silicon nitride densification process. The top silicon dioxide is generally deposited using a furnace tube HTO (high-temperature oxidation) process, followed by an HTO densification process. In this embodiment of the invention, the ONO layer is formed by sequential deposition using a low-pressure chemical vapor deposition (LPCVD) method. A uniform silicon oxide layer is formed by LCVD, followed by a silicon nitride layer formed on the silicon oxide layer by LCVD, and then another silicon oxide layer is formed by LCVD. The thickness of each film layer is not described in detail here.

[0034] In this embodiment of the invention, the trench etching is a dry etching method. More specifically, the trench etching employs a dry etching method primarily using fluorine-based plasma, which can etch both oxides and silicon nitride, as well as the silicon substrate, thereby forming a side-cut structure on the wafer, such as... Figure 3 As shown, Figure 3 The diagram shown is a schematic diagram of the side-hole structure wafer according to an embodiment of the present invention.

[0035] Step 2: Use a wet etching machine to perform wet etching on the wafer to remove the oxide layer.

[0036] In this embodiment of the invention, the side-cut structure wafer is placed in a wet etching (WET) machine for wet etching to remove the oxide layer. The removed oxide layer consists of the top TEOS layer and the exposed HTO layer on the side. Figure 4 As shown, the HTO layer beneath the SiN layer is missing, creating a gap. If the drying capacity of the WET machine is insufficient, water marks (wafer marks) can easily form in the gap, as indicated by the arrow in the figure.

[0037] Step 3: Perform thermal oxidation treatment on the surface of the bare wafer to form a sacrificial oxide layer.

[0038] In this embodiment of the invention, the thermal oxidation process is furnace tube thermal oxidation growth. A sacrificial oxide layer is grown using furnace tube thermal oxidation. The sacrificial oxide layer is formed by oxidizing the exposed Si on the bare wafer surface.

[0039] Step 4: Etch to remove the SiN layer and sacrificial oxide layer.

[0040] In this embodiment of the invention, the etching removal of the SiN layer and the sacrificial oxide layer employs a dry etching process, a wet etching process, or a combination of both. This embodiment utilizes the fact that insufficient drying in the gaps of a side-hole structure wafer easily leads to watermarks, which, during oxide growth and removal, will create pit defects. In step two, if the drying capacity of the WET machine is insufficient, watermarks (wafer marks) will form in the gaps, and then after steps three and four, pits (pits) will appear on the wafer surface. Figure 5 As indicated by the middle arrow, there are pit defects on the wafer surface.

[0041] Step 5: Use a scanning machine to perform yield measurement and defect scanning on the wafer. If the defect scanning result is a pit defect, the verification fails; otherwise, the verification passes.

[0042] Perform yield measurement and defect scanning on wafers, such as Figure 6 and Figure 7 The image shown is a wafer image and SEM image of a side-hole structure wafer with pit defects according to an embodiment of the present invention; as shown Figure 8 and Figure 9 The image shown is a wafer image and SEM image of a side-hole structure wafer without pit defects according to an embodiment of the present invention. In this embodiment, if the yield measurement is qualified and the defect scanning results show no pit defects, it indicates that the drying capability verification of the WET machine has passed and it can be used normally. If the yield is unqualified and pit defects exist, it indicates that the drying capability of the WET machine needs to be further optimized and enhanced.

[0043] In summary, this invention utilizes the principle that insufficient drying gaps in side-cut wafers easily generate watermarks, which, after oxide growth and removal, will produce pit defects. By employing side-cut wafers, the oxide layer of the side-cut wafers is etched using a WET machine. After furnace tube thermal oxidation growth and oxide layer removal, the drying capability of the WET machine is verified through yield measurement and defect results. This improves the monitoring of the drying capability of the WET machine and can further improve the device yield.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for verifying the drying capability of a wet etching machine, characterized in that, Includes the following steps: Step 1: Provide a wafer with a side-hole structure, wherein the side-hole structure is formed by depositing an ONO layer on the surface of the bare wafer and then performing trench etching. The ONO layer includes a bottom HTO layer, an intermediate SiN layer and a top TEOS layer. Step 2: Use a wet etching machine to perform wet etching on the wafer to remove the oxide layer; the removed oxide layer includes the top TEOS layer and the exposed portion of the HTO layer on the side; Step 3: Perform thermal oxidation treatment on the surface of the bare wafer to form a sacrificial oxide layer; Step 4: Etch away the SiN layer and the sacrificial oxide layer; Step 5: Use a scanning machine to perform yield measurement and defect scanning on the wafer. If the defect scanning result is a pit defect, the verification fails; otherwise, the verification passes.

2. The method for verifying the drying capability of a wet etching machine according to claim 1, characterized in that, The material of the wafer mentioned in step one is silicon.

3. The method for verifying the drying capability of a wet etching machine according to claim 1, characterized in that, The ONO layer described in step one is formed by sequential deposition using a low-pressure chemical vapor deposition method.

4. The method for verifying the drying capability of a wet etching machine according to claim 1, characterized in that, The trench etching described in step one is dry etching.

5. The method for verifying the drying capability of a wet etching machine according to claim 1, characterized in that, The thermal oxidation treatment described in step three is furnace tube thermal oxidation growth.

6. The method for verifying the drying capability of a wet etching machine according to claim 1, characterized in that, The etching described in step four includes both dry and wet etching.

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