Tomographic sample preparation of detector arrays and 3D functional electronic structure detection methods

Abstract

This application discloses a method for tomographic sample preparation and 3D functional electronic structure detection of a detector array, relating to the field of detector measurement. The method comprises: using a dissociation process to dissociate the detector layer by layer; and using a scanning capacitance microscope to detect the differential capacitance signal of the detector dissociation surface to analyze the detector's three-dimensional functional structure. This application uses a slice method along the photosensitive element string to achieve horizontal and vertical analysis of the internal functional structure of the infrared chip, thereby improving the resolution dimension and defect visualization capabilities.

Description

Technical Field

[0001] The present application relates to the field of detector measurement, and in particular to a method for tomographic sample preparation of a detector array and a 3D functional electronic structure detection method. Background Art

[0002] Infrared detectors are widely used in optoelectronic imaging, environmental monitoring, laser communications, and space remote sensing. Multilayer heterostructure chips composed of materials such as InGaAs and HgCdTe are core components for high-performance short-wave and medium-wave infrared detection. These devices have a complex layered structure, with light absorption, carrier generation, and collection all occurring vertically (on the Z axis). Their photosensitive regions typically have a circular or array layout, exhibiting spatial non-uniformity in the lateral (XY) directions.

[0003] Current mainstream electrical measurement methods, such as dark current, spectral response, and responsivity, can reflect macroscopic performance but struggle to reveal microscopic mechanisms such as detector structural defects, interface states, and carrier distribution. In particular, they lack spatially resolved information, limiting their ability to quantitatively diagnose detector failures and process deviations. Existing micro- and nanostructure characterization methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and three-dimensional atom probe microscopy (APT), while capable of morphological resolution from nanometer to atomic scales, are unable to intuitively provide spatial carrier information or junction states directly related to electrical function.

[0004] Furthermore, current research on device internal structures often relies on two-dimensional cross-sectional analysis, observing and measuring the structure through a single dissociated plane. This two-dimensional approach severely limits understanding of the device's overall three-dimensional structure and its functional distribution, particularly in identifying structural symmetry violations, localized defect distribution, or electrical property gradients across different cross-sectional dimensions. Summary of the Invention

[0005] The purpose of the present invention is to provide a tomographic sample preparation and 3D functional electronic structure detection method for a detector array, combining a scanning capacitance microscope to characterize multiple dissociation surfaces and reconstruct a three-dimensional structural function map inside the detector.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] A method for tomographic sample preparation and 3D functional electronic structure detection of a detector array, the method comprising:

[0008] The detector array is dissociated layer by layer using a dissociation process to obtain the dissociation surfaces of each layer;

[0009] A scanning capacitance microscope is used to detect the differential capacitance signal of the dissociation surface of the detector array to analyze the three-dimensional functional structure of the detector.

[0010] The present invention has the following beneficial effects:

[0011] 1. This invention introduces for the first time a method for obtaining cross-sections using "multi-chordal dissociation." Traditional cross-section sample preparation typically only performs a single dissociation along the vertical (Z-axis) axis, failing to reveal lateral structural features. This invention innovatively designs multiple dissociation paths along different chordal directions of the photosensitive element (e.g., diameter, eccentric chord, dual radius, etc.), enabling visualization and analysis of lateral structural differences, symmetry breaking, and edge effects.

[0012] 2. The present invention realizes three-dimensional functional structure reconstruction. By spatially aligning and fusing differential capacitance images obtained from multiple chordal sections, the present invention can reconstruct the three-dimensional structural functional map of the detector, which is impossible with traditional two-dimensional electrical analysis, thereby expanding the dimension of infrared chip structure analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The microscopic images of the present invention before and after dissociation along different chords of the detector photosensitive element;

[0014] Figure 2 The three-dimensional structure of the detector is formed by arranging and combining differential capacitance signals of different chordal cross sections in the present invention. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned objectives, the present invention adopts the following technical solutions.

[0016] The present invention provides a method for tomographic sample preparation of a detector array and detection of a 3D functional electronic structure, comprising the following steps:

[0017] The detector is dissociated layer by layer using a dissociation process to obtain the dissociation surfaces of each layer;

[0018] A scanning capacitance microscope is used to detect the differential capacitance signal of the dissociation surface of the detector to analyze the three-dimensional functional structure of the detector.

[0019] Optionally, each unit of the detector array shares the same piece of epitaxial material, and the preparation process is completely consistent.

[0020] Optionally, the dissociation surface passes through a photosensitive element region of the detector.

[0021] Optionally, the dissociation surface passes through different chords (such as diameter, half diameter, eccentric chord, etc.) of the detector photosensitive element.

[0022] Optionally, the minimum interval between the different chords can be 1.5 microns.

[0023] Optionally, when a dissociation process is used to prepare a dissociation surface of the detector, the dissociation is aligned with the cracking crystal direction so that the flatness of the dissociation surface of the detector reaches the atomic level.

[0024] Alternatively, a scanning capacitance microscope (SCM) can be used to measure the differential capacitance distribution of the detector at different chord-wise dissociation planes. In SCM, a radio frequency signal is transmitted to the AFM probe via a coupler, forming a reflected signal between the AFM probe and the sample, which is used to characterize the local capacitance characteristics. Simultaneously, a bias voltage is applied to the sample to modulate the carrier distribution, causing changes in the local capacitance characteristics. This results in a capacitance-voltage curve, which is then derived to obtain a two-dimensional differential capacitance distribution.

[0025] Alternatively, the differential capacitance signals of the detector at different chordal dissociation planes are arranged and combined to map the three-dimensional functional structure of the detector. The resulting two-dimensional differential capacitance distribution maps are stacked in sequence (x-axis) to form the three-dimensional functional structure of the detector.

[0026] Optionally, the differential capacitance distribution diagrams are arranged in a sequence of chord lines.

[0027] The following will be combined with a typical infrared detector (taking InGaAs as an example) to clearly and completely describe the technical solutions in the embodiments of the present application. This embodiment does not constitute a limitation on the scope of protection of the present invention.

[0028] In an exemplary embodiment, Figure 1 As shown, the device used is an InGaAs shortwave infrared detector array. This detector employs a typical PIN structure, consisting of a circular photosensitive element, an electrode structure, an epitaxial absorption layer, and an InP substrate. Each detector unit has a diameter of approximately 50 microns and is arranged in a regular array. All detector units in the array share the same epitaxial material and are fabricated using a completely identical process to ensure structural comparability and experimental consistency.

[0029] In this example, a diamond tool was used to physically dissociate the device sample, cutting along four pre-defined chordal paths. All dissociation paths passed through the circular photosensitive element region of the detector unit, ensuring that each path contained cross-sectional information about key functional structures. Figure 1 The four string-shaped photosensitive elements formed after dissociation are schematically shown to ensure that each dissociation surface has a complete PIN structure.

[0030] After completing the multi-chordal dissociation of the detector, a scanning capacitance microscope is used to perform a two-dimensional scan of the dissociation surface. The differential capacitance distribution images on the chordal cross section are extracted. These images can reflect functional characteristics such as carrier concentration, capacitance change, and junction boundaries in the local area.

[0031] Then, according to the spatial position relationship of each string in the circular photosensitive element, the four differential capacitance images are sorted and spatially registered to construct the three-dimensional functional structure distribution inside the detector. Figure 2 The results of this reconstruction process are shown schematically.

[0032] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for tomographic sample preparation and 3D functional electronic structure detection of a detector array, characterized in that: The method comprises: Performing layer-by-layer dissociation processing on the target detector array to obtain multiple dissociation surfaces; Using a scanning capacitance microscope to detect the differential capacitance signal of the dissociation surface of the detector array to restore the three-dimensional functional structure inside the detector; The dissociation surface passes through different chords of the detector photosensitive element; The obtained two-dimensional differential capacitance distribution maps are stacked in sequence to form the three-dimensional functional structure of the detector.

2. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 1, characterized in that: Each unit of the detector array is prepared on the same epitaxial wafer, and the preparation process is completely consistent.

3. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 1, characterized in that: The minimum interval between different chords of the detector's photosensitive elements is 1.5 microns.

4. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 2, characterized in that: When the dissociation surface of the detector is prepared by using the dissociation process, the dissociation is aligned with the cracking crystal direction so that the flatness of the dissociation surface of the detector reaches the atomic level.

5. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 1, characterized in that: The differential capacitance distribution of the detector at different chordal dissociation surfaces was measured using a scanning capacitance microscope.

6. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 1, characterized in that: Different chord types include diameter, half diameter, and eccentric chords.

7. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 5, characterized in that: The method for obtaining the differential capacitance distribution map is as follows: in a scanning capacitance microscope, the radio frequency signal is transmitted to the AFM probe through a coupler, forming a reflected signal between the AFM probe and the sample, which is used to characterize the local capacitance characteristics. At the same time, by applying a bias voltage to the sample to modulate the carrier distribution, causing the local capacitance characteristics to change, and obtaining a capacitance-voltage curve. The capacitance-voltage curve is then derived to obtain a two-dimensional differential capacitance distribution map.

8. The method for tomographic sample preparation and 3D functional electronic structure detection of a detector array according to claim 6, characterized in that: The differential capacitance signals are arranged in the order of the strings.

Images