Internal nanoscale nondestructive testing method for high-hardness semiconductor without ultrathin sample preparation

Abstract

The invention relates to an internal nanoscale nondestructive testing method for a high-hardness semiconductor without ultrathin sample preparation, belongs to the field of semiconductor nanoscale precision imaging, and mainly solves the problems that the semiconductor material is hard, ultrathin sample preparation is difficult to carry out, and nondestructive testing is difficult to carry out on internal nanoscale defects. A semiconductor surface is detected by utilizing an atomic force microscope with nanoscale precision, a beam of electromagnetic waves is added at the position of a probe tip of an atomic force probe, so that the electromagnetic waves capable of penetrating through the interior of the semiconductor enter the interior, and the electromagnetic waves carry internal information and are combined with the nanoscale precision of the atomic force microscope; therefore, nano-scale imaging in the semiconductor is realized. The method is suitable for internal imaging of semiconductor materials, and is especially suitable for semiconductors with high material hardness.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor nanometer precision imaging, and particularly relates to a non-destructive testing method for the internal nanometer level of a high-hardness semiconductor without ultra-thin sample preparation. BACKGROUND

[0002] Semiconductor is a material with special electrical properties, with electrical conductivity between conductor and insulator, playing a core role in modern electronic information technology. Element semiconductors such as silicon and germanium, compound semiconductors such as gallium arsenide, gallium nitride, silicon carbide, and indium phosphide, emerging semiconductor two-dimensional materials such as graphene and molybdenum disulfide, and oxide semiconductors such as indium tin oxide. Semiconductors support smartphones, cloud computing, artificial intelligence, and the Internet of Things technology, and are the core of national defense equipment radar and missiles, key infrastructure power grids and communications. Semiconductor power devices can improve the energy conversion efficiency of new energy vehicles and photovoltaic inverters, and reduce carbon emissions. Specifically, it includes silicon used to manufacture integrated circuits and power devices, germanium used for high-frequency devices, gallium arsenide used for 5G radio frequency chips, microwave devices, and lasers; gallium nitride used for fast-charging chips and power devices; silicon carbide used for electric vehicle inverters, rail transit power modules, and charging piles, etc.

[0003] With the development of Moore's Law, semiconductors are shrinking in size, from centimeters to atomic scales (nanometers), which puts high demands on defect detection equipment. Not only the surface is detected at the nanometer level, but the internal defects are also detected. Conventional optical detection equipment has a resolution of hundreds of nanometers due to the diffraction limit, which cannot meet the current requirements of high-process nanometer precision (11 nm or even 7 nm) of semiconductors. Currently, there are polarization interferometers, atomic force microscopes, and electron microscopes for semiconductor nanometer-level detection equipment. Polarization interferometers require the material itself to be transparent, mainly for height measurement such as silicon-based semiconductors. Currently, materials with high hardness such as silicon carbide and gallium nitride are not transparent and cannot be detected. Atomic force microscopes mainly measure the surface and cannot detect internal defects of all semiconductors. Electron microscopes are divided into scanning and transmission types. In theory, they can observe both surface and internal nanometer-level defects, but semiconductors with high hardness such as silicon carbide and gallium oxide are difficult to make ultra-thin samples required by transmission electron microscopes due to their high hardness, making it impossible to detect nanometer-level defects in high-hardness semiconductors. Therefore, there is almost no detection method for high-hardness semiconductors with nanometer precision, resulting in a lack of quality control in the production and application of such semiconductors, and there is an urgent need for a technical solution. SUMMARY

[0004] To address the challenge of detecting nanoscale internal structures in semiconductors due to their high hardness, opacity, and difficulty in preparing ultra-thin samples, this invention utilizes an atomic force microscope with nanoscale precision to inspect the semiconductor surface. By adding a beam of electromagnetic waves capable of penetrating the semiconductor's interior to the probe tip, nanoscale information about the semiconductor's internal structure can be obtained. This effectively solves the problem of imaging the internal nanoscale structures of semiconductors that are both hard and opaque.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A novel nanoscale non-destructive testing method for the internal structure of high-hardness semiconductors, eliminating the need for ultra-thin sample preparation, utilizes a nanoscale precision atomic force microscope (AFM) for semiconductor surface inspection. An electromagnetic wave beam capable of penetrating the semiconductor's interior is added to the probe tip. To facilitate better transmission of the electromagnetic wave signal to the semiconductor, the probe's material and shape are adjusted compared to a standard AFM probe, allowing the electromagnetic wave to transmit downwards towards the semiconductor. The electromagnetic wave is focused onto the nanoscale precision probe tip. The nanoscale tip has specific requirements for the frequency band and power of the electromagnetic wave; a suitable frequency band ensures the electromagnetic wave pattern and the energy density transmitted through the semiconductor. This method, combining electromagnetic wave penetration with nanoscale precision atomic force microscopy for internal semiconductor imaging, achieves nanoscale precision imaging of the semiconductor's interior, making it particularly suitable for semiconductors with high material hardness.

[0007] The beneficial effects of this invention are as follows:

[0008] This invention provides a method to add a beam of electromagnetic waves that can penetrate the interior of a semiconductor by adding a probe tip, which can perform nanometer-level precision imaging of the semiconductor interior, especially in semiconductors with high material hardness. Compared with optical microscopes, it has higher precision, and compared with electron microscopes, it avoids the complex ultra-thin sample preparation.

[0009] This invention can ensure the energy density of electromagnetic wave spots and transmission semiconductors by selecting the frequency band and power level. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a probe and electromagnetic waves.

[0011] In the figure: 1-electromagnetic wave, 2-probe tip, 3-probe cantilever, 4-front end of probe substrate for atomic force microscope, 5-front end of probe substrate for internal imaging. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0013] This invention provides a method for non-destructive testing of internal nanoscale high-hardness semiconductors without the need for ultra-thin sample preparation, such as... Figure 1 As shown, a special probe of an atomic force microscope with nanometer-level precision is used to ensure that more of the electromagnetic wave 1 signal penetrates into the underlying semiconductor. A specific frequency electromagnetic wave 1 is focused at the probe tip 2. The power and energy of the electromagnetic wave can penetrate the interior of the semiconductor. After penetration, the electromagnetic wave carries internal information with nanometer-level precision comparable to that of an atomic force microscope, thereby achieving nanometer-level imaging of the semiconductor interior. Details are as follows:

[0014] 1. Special probe:

[0015] Special probes are those used in atomic force microscopes (AFMs) and are special in their materials and shape, as opposed to probes commonly used in AFMs. AFM probes are made of silicon or silicon nitride, both semiconductors or insulators. The cantilever length (3) of an AFM probe extends from the probe tip (2) to the front end (4) of the probe substrate, typically around 100 micrometers. Considering that electromagnetic signals must penetrate the semiconductor beneath the tip through the probe tip, the material must be non-penetrating; it cannot be a semiconductor or insulator. Therefore, the probe tip material is either a metal impermeable to electromagnetic waves or a metal plating on a commonly used probe tip. If metal plating is used, the plating thickness must exceed the skin depth for that frequency band. Considering that electromagnetic waves propagate at the probe tip in a radiative form, the substrate metal layer affects the electric field at the tip, generally increasing the cantilever length by more than twice that of commonly used probes. Figure 1 The distance from the probe tip 2 to the front end 5 of the probe substrate used for internal imaging is selected to be approximately 200 micrometers. In summary, the special probe is characterized by its special material and cantilever length; the material is metal or coated with a metal layer, and the cantilever length is more than twice that of commonly used probes.

[0016] 2. Specific electromagnetic wave frequency bands:

[0017] The key to internal imaging is focusing a specific frequency band of electromagnetic waves at the probe tip. Semiconductor internal imaging requires electromagnetic waves that can reach the interior, do not cause harm, and have the shortest possible wavelength. Electromagnetic waves are categorized by wavelength from longest to shortest: radio waves, microwaves, infrared, visible light, ultraviolet light, X-rays, and gamma rays. Based on the ability to reach the interior, electromagnetic waves in the infrared, visible light, and ultraviolet frequency bands that cannot penetrate opaque materials are excluded. Based on the principle of not causing harm, electromagnetic waves in the high-energy X-ray and gamma-ray frequency bands are excluded. The remaining frequency bands are radio waves and microwaves. Following the principle of the shortest possible wavelength, the microwave frequency band is the infrared end of the microwave spectrum, commonly referred to as the submillimeter wave band in electronics and the far-infrared band, also known as the terahertz band in optics. The frequency is generally from 100 GHz to 10 THz, and the wavelength is from 3 millimeters to 30 micrometers. Considering the manufacturing maturity and price of power source devices in this band, a frequency band around 3 millimeters in wavelength is generally chosen. In summary, the specific electromagnetic wave frequency band is the frequency band around 3 millimeters in wavelength.

[0018] 3. Electromagnetic wave power energy:

[0019] Electromagnetic waves are focused at the probe tip, and their power can penetrate the semiconductor, carrying internal information back with them. The power of the electromagnetic waves, after being focused by the probe, penetrates the semiconductor and returns, placing energy requirements on the electromagnetic wave source. Due to spatial constraints, the electromagnetic wave source is a certain distance from the probe tip. Electromagnetic waves in the 3mm band experience significant propagation losses in space, typically 3-5dB. When the electromagnetic beam is focused at the tip, the difference between the nanoscale tip and the millimeter-scale wave spot is at least 3-4 orders of magnitude, resulting in an energy loss of 20-30dB. Energy is further lost as it travels through the tip into the semiconductor, considering interface effects and lattice distribution, totaling 26-40dB. Returning along the same path, energy is lost again. Therefore, even without considering other losses, the energy degradation is 30-40dB. To effectively extract internal imaging information, a higher electromagnetic wave source power is desirable. However, considering the current overall power level in this frequency band, a power of 100 milliwatts or higher is generally chosen as the wave source. In summary, the higher the power of electromagnetic waves, the better; generally, a power of 100 milliwatts or more is chosen.

[0020] This invention utilizes a special probe of an atomic force microscope with nanometer-level precision. A beam of electromagnetic waves in a specific frequency band is focused at the probe tip. The power of these electromagnetic waves can penetrate the interior of a semiconductor, carrying internal information with nanometer-level precision comparable to that of an atomic force microscope, thus achieving nanometer-level imaging of the semiconductor's interior. The advantage of this invention is that it can perform nanometer-level precision imaging of the interior of semiconductors, especially those with high material hardness.

Claims

1. A method for non-destructive testing of the internal nanoscale of high-hardness semiconductors without the need for ultra-thin sample preparation, characterized in that, By using the probe of an atomic force microscope with nanometer-level precision, a beam of electromagnetic waves with a specific frequency band and power is focused at the tip of the probe. The power energy of the electromagnetic waves penetrates the inside of the semiconductor, and after penetration, the electromagnetic waves carry internal information with nanometer-level precision comparable to that of an atomic force microscope, thereby realizing nanometer-level imaging inside the semiconductor.

2. The method for internal nanoscale non-destructive testing of high-hardness semiconductors without the need for ultra-thin sample preparation, as described in claim 1, is characterized in that... The probe is made of metal or a metal-plated layer.

3. The method for internal nanoscale non-destructive testing of high-hardness semiconductors without the need for ultra-thin sample preparation, as described in claim 1, is characterized in that... The electromagnetic wave frequency band is the band with a wavelength of about 3 millimeters.

4. The method for internal nanoscale non-destructive testing of high-hardness semiconductors without the need for ultra-thin sample preparation, as described in claim 1, is characterized in that... Choose an electromagnetic wave power of 100 milliwatts or more.

5. The method for internal nanoscale non-destructive testing of high-hardness semiconductors without the need for ultra-thin sample preparation, as described in claim 1, is characterized in that... The probe's cantilever length is over 200 micrometers.

6. The method for internal nanoscale non-destructive testing of high-hardness semiconductors without the need for ultra-thin sample preparation, as described in claim 1, is characterized in that... High-hardness semiconductors include silicon carbide and gallium nitride.

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