Dear Jingli Zhong

Cleaning the substrate after KOH (potassium hydroxide) etching is an important step to remove residues and contaminants that may be left on the surface. Ultrasonic cleaning can indeed be a suitable method for this purpose. Here are general steps to clean a substrate after KOH etching:

Materials and Equipment:

• Substrate after KOH etching
• Distilled water
• Isopropyl alcohol (IPA)
• Ultrasonic cleaner
• Compressed air or nitrogen (optional)
• Cleanroom wipes or lint-free wipes

Steps:

Always consider the specific requirements of your application and the material of your substrate when choosing cleaning methods and solutions. Additionally, follow safety guidelines when working with chemicals like KOH and ensure proper disposal of waste materials.

Len Leonid Mizrah非常感谢您回答我的问题。前天，我们用超声波清洗了一下，发现了不同的效果。硅晶圆上有一些我们以前从未见过的东西。但我们目前还不确定这些新事物是什么。同时，我还有一个问题：如果我们在腐蚀后的硅上看到一些缺陷，我们是否有标准来比较这些缺陷的具体名称？如何区分这些缺陷是硅本身固有的还是在腐蚀过程中引入的？非常期待您的回答，谢谢！

Dear Jingli Zhong ,

当观察硅在蚀刻过程后出现缺陷时，确实存在用于比较和分类这些缺陷的标准和方法。半导体制造遵循特定的质量控制标准，而缺陷分析是确保半导体器件可靠性和性能的不可或缺的部分。

标准和分类：

国际技术和行业组织通常会制定半导体制造的标准。像SEMI（半导体设备和材料国际协会）这样的组织提供了根据缺陷的大小、形状和对器件性能的影响进行分类的准则。 缺陷通常被分类为颗粒、划痕、污染或其他类型，根据它们的特征。SEMI标准包括根据缺陷对器件功能的影响对缺陷进行分类的标准。 缺陷检查和计量：

先进的检测工具，如扫描电子显微镜（SEM）和光学检测系统，用于在微观水平上检查硅晶圆。 计量工具测量晶圆表面特征的尺寸和属性，有助于准确地表征缺陷。 根本原因分析：

像聚焦离子束（FIB）显微镜这样的技术可以用来进行晶圆的横截面分析，有助于确定缺陷的深度和性质。 分析缺陷的形态和它们在晶圆上的分布可以提供有关它们起源的见解。 固有缺陷与过程诱导缺陷：

固有缺陷是在原始硅材料中存在的，或者是在半导体制造的初期阶段引入的（例如，晶体生长）。 过程诱导缺陷发生在随后的制造步骤中，如蚀刻、沉积或光刻过程中。 比较分析：

比较分析涉及将观察到的缺陷与已知的缺陷库和数据库进行比较。这有助于识别共同的问题并了解它们对器件性能的潜在影响。 总的来说，半导体行业已经建立了缺陷分析的成熟方法和标准。其目标是识别、分类和解决缺陷，以确保半导体器件的质量和可靠性。先进的检测和分析技术在这一过程中起着至关重要的作用。

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When observing defects on silicon after the etching process, there are indeed standards and methods to compare and categorize these defects.

Semiconductor manufacturing follows specific quality control standards, and defect analysis is an integral part of ensuring the reliability and performance of semiconductor devices.

Standards and Classification: International technology and industry organizations often establish standards for semiconductor manufacturing. Organizations like SEMI (Semiconductor Equipment and Materials International) provide guidelines for classifying defects based on their size, shape, and impact on device performance. Defects are typically classified as particles, scratches, contamination, or other types based on their characteristics. The SEMI standards include criteria for categorizing defects according to their impact on device functionality.

Defect Inspection and Metrology: Advanced inspection tools, such as scanning electron microscopes (SEM) and optical inspection systems, are used to examine silicon wafers at a microscopic level. Metrology tools measure the dimensions and properties of features on the wafer surface, helping to characterize defects accurately.

Root Cause Analysis: Techniques like focused ion beam (FIB) microscopy can be employed to perform cross-sectional analysis of the wafer, helping to identify the depth and nature of defects. Analyzing the morphology of defects and their distribution across wafers can provide insights into their origin.

Inherent vs. Process-Induced Defects: Inherent defects are those present in the raw silicon material or introduced during the initial stages of semiconductor manufacturing (e.g., crystal growth).

Process-induced defects occur during subsequent manufacturing steps, such as etching, deposition, or lithography.

Comparative Analysis: Comparative analysis involves comparing the observed defects with known defect libraries and databases. This helps in identifying common issues and understanding their potential impact on device performance.

In summary, the semiconductor industry has well-established methodologies and standards for defect analysis. The goal is to identify, categorize, and address defects to ensure the quality and reliability of semiconductor devices. The use of advanced inspection and analysis techniques plays a crucial role in this process.

Len Leonid Mizrah

Thank you very much for your reply. You are a very lovely person, and I didn't expect you to reply to me in Chinese. It was only then that I realized that I was sending in Chinese. I am very sorry.

SEMI is a great platform, and just now I took a rough look and there are indeed many standards related to silicon in it. Later, I will see how to download these standards.

I often see SEM detection methods in some papers and it is a very good method. Can we use DIC instead of SEM? FIB is relatively rare, perhaps because I have read too few articles, I will make up for it later. The depth of defects is very important, for example, for some stacking faults, their depth needs to be observed. Can we use photoluminescence (PL) to measure depth?

Looking forward to your reply. Best wishes for you！

Dear Jingli Zhong

Scanning Electron Microscopy (SEM) is commonly used for defect detection in semiconductor materials due to its high spatial resolution and ability to provide detailed surface morphology images. Differential Interference Contrast (DIC) microscopy, on the other hand, is a technique that enhances the contrast in unstained, transparent samples, often used in biological studies. While DIC microscopy is valuable in certain contexts, it may not be the ideal choice for imaging semiconductor materials, especially for detecting small defects.

Focused Ion Beam (FIB) microscopy is indeed less common than SEM but is a powerful technique for both imaging and sample preparation. FIB can be used for cross-sectional analysis, allowing researchers to investigate the depth and internal structure of defects in semiconductor materials.

Regarding the use of Photoluminescence (PL) for measuring the depth of defects, PL is a spectroscopic technique that involves the emission of light observed when a material absorbs photons and re-emits them. It is commonly used to study the electronic properties of semiconductors, including defects. However, PL is generally not well-suited for directly measuring the depth of defects.

To observe the depth of defects, especially in the case of stacking faults, alternative techniques such as Transmission Electron Microscopy (TEM) or FIB cross-sectioning are often more appropriate. TEM provides extremely high-resolution images and can reveal detailed information about the structure and depth of defects.

In summary, while SEM is a commonly used method for defect detection in semiconductor materials, other techniques like FIB and TEM are often more suitable for in-depth analysis of defects. Photoluminescence, while useful for certain purposes, may not be the best choice for measuring the depth of defects in semiconductor materials. The choice of technique depends on the specific requirements of the study and the type of information researchers seek to obtain.

Good luck!

Dear Len Leonid Mizrah

Thank you very much for your patient answer.

First of all, I apologize for my unclear statement. We intended to use PL to observe non surface defects. After reading some papers, it was stated that PL can be used to observe deeper defects that cannot be observed by ordinary optical microscopes. But we have not yet carried out the construction of the optical path.

Because we want to use optical detection to detect defects, we consider using DIC to detect the unevenness on the surface of silicon wafers. Then, by combining PL, we can detect defects on the silicon surface and deeper ones. Of course, we are still in the theoretical stage and are looking for a theoretical basis for whether this method is feasible.

Thank you again for your reply, and we look forward to your other thoughts and opinions. We would greatly appreciate it if you could give us a response.

Dear Jingli Zhong

Digital Image Correlation (DIC) and Photoluminescence (PL) are two distinct techniques with different applications, but they can potentially be combined for defect detection on silicon wafers.

Combining DIC and PL:

• Surface Inspection: Use DIC to identify surface irregularities and deformations on the silicon wafer.
• Defect Detection: Implement PL to analyze the photoluminescent properties of the wafer, focusing on detecting defects within the material, whether on the surface or at deeper layers.
• Comprehensive Analysis: Combining these techniques can provide a more comprehensive analysis of the silicon wafer, addressing both surface conditions and internal defects.

Considerations:

• Integration Challenges: Combining these techniques may pose challenges in terms of equipment integration and synchronization of data.
• Data Fusion: The challenge is to integrate and interpret the data from DIC and PL to provide a coherent assessment of the silicon wafer's quality.
• Cost and Complexity: Implementing both DIC and PL systems may increase the overall cost and complexity of the inspection process.

Conclusion: Using DIC for surface inspection and PL for defect detection on silicon wafers can be a viable solution, offering complementary information about the wafer's quality. However, it's essential to carefully plan and assess the integration challenges, costs, and benefits associated with each technique to determine the most suitable approach for your specific requirements.

Dear Len Leonid Mizrah

First of all, I'm sorry for replying to you so late.

Recently, I have been searching for relevant literature for learning, and I increasingly feel that there is a lot of knowledge to learn about building light paths. Thank you again for your reply, and best wishes.