A Multi-Frequency Parallel Modulated Scattering Electromagnetic Wave Vector Distribution Measurement System and Method

Abstract

This invention relates to a multi-frequency parallel modulation scattering electromagnetic wave vector distribution measurement system and method. Based on the principle of modulation scattering, the design uses a modulated light source to illuminate a semiconductor wafer, forming plasma that scatters the electromagnetic wave to be measured. The electromagnetic wave signal can be received at the difference frequency between the measured frequency and the modulation frequency. The light source units are arranged into a light source array, and each light source array unit is set to a different modulation frequency. A high-speed broadband sweep frequency receiver or a parallel multi-channel receiver is used to receive electromagnetic wave signals with different difference frequencies, allowing for rapid measurement of the electromagnetic wave amplitude and phase distribution within the test area. This invention features a simple system structure, eliminating any mechanical scanning devices and additional fixtures, offering advantages in measurement speed and accuracy. It also avoids the influence of cable movement during testing on the electromagnetic wave distribution at the test location, making it a fast and effective measurement method.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave measurement, specifically relating to a multi-frequency parallel modulation scattering electromagnetic wave vector distribution measurement system and method. Background Technology

[0002] The measurement of electromagnetic field distribution is a fundamental and crucial aspect of the field of electromagnetic measurement. Measuring the distribution of electromagnetic fields within a spatial region has wide applications in areas such as material electrical performance testing, antenna measurement, electromagnetic compatibility, and electromagnetic imaging. Currently, a relatively mature and commonly used method for measuring electromagnetic field distribution is the use of near-field measurement probes. A common near-field measurement probe is an open waveguide, which is fixed to a two-dimensional mechanical scanning frame using a clamp. The scanning frame is controlled to move the probe to the measurement position and collect the signal. This process is repeated until the signal within the measurement area is complete. Typically, the spatial sampling interval should satisfy the Nyquist sampling law. Therefore, for higher frequencies, a large number of spatial sampling points are required, consuming a significant amount of time to complete a single electromagnetic field distribution measurement. Furthermore, at higher frequencies, the positioning accuracy of the scanning frame and the errors caused by the movement of the RF cable during probe movement will affect the accuracy of the electromagnetic field distribution measurement results.

[0003] To address the problems of probe-based electromagnetic field distribution measurement systems, J.R. H. Ichmond published "AModulated Scattering Technique for Measurement of Field Distributions" in IRE Transactions on Microwave Theory and Techniques 3(4), 13-15 (1955). This measurement method uses a small "electric dipole" made from the elements of nonlinear impedance as an equivalent measurement probe. The impedance of this probe changes periodically with the modulation frequency, thus scattering a signal with a frequency difference from the frequency to be measured. This measurement method does not require connecting the RF cable to the probe, thus effectively avoiding errors introduced by the cable following the probe when it moves. However, this measurement method still requires a mechanical device to carry the probe, which cannot reduce the measurement time. Bai Ming et al. published a patent titled "Rapid Measurement Method and System for Amplitude and Phase Distribution of Electromagnetic Waves by Optical Scanning" (Patent No.: ZL202110759705.1), which proposed a method for measuring the distribution of electromagnetic waves by scanning a light beam on a semiconductor wafer. This measurement method can effectively improve the testing efficiency, but the use of mechanical devices, such as laser galvanometers, is still unavoidable when scanning the light beam. The use of mechanical devices will introduce positioning errors in the light beam position, reduce the testing accuracy, and the testing speed will be limited by the mechanical devices.

[0004] The photoconductivity of semiconductor materials refers to the increase in conductivity of the irradiated area when light shines on the material. With increased conductivity, this area scatters electromagnetic waves. Combining this with the concept of modulated scattering, when light of a specific modulation frequency shines on a semiconductor material, the area will scatter a signal with a frequency difference from the frequency being measured. Utilizing this principle, this invention proposes using an array of light sources to irradiate the semiconductor. Each light source array unit operates at a different modulation frequency, and by using a signal receiving and processing device to collect signals of different frequencies, the distribution of the electromagnetic field in space can be quickly obtained. Each light source array unit is equivalent to an "equivalent probe," with a small focused spot size. Spatial arrangement effectively improves measurement resolution. This measurement method eliminates the need for any mechanical scanning devices, improving measurement speed while effectively avoiding errors caused by mechanical positioning accuracy and RF cable movement in high-frequency measurements. Combined with a parallel multi-channel signal receiving device, near real-time electromagnetic wave vector distribution measurement can be achieved. Summary of the Invention

[0005] The purpose of this invention is to propose a measurement system and method for electromagnetic wave vector distribution of multi-frequency parallel modulation scattering. This measurement system does not require spatial movement scanning, thus improving testing efficiency; it does not have a mechanical scanning structure, and the position of each light source array unit is fixed, avoiding the positioning accuracy problem when conventional probes move; the positions of the RF cable and the receiving antenna are fixed during the testing process, avoiding the error introduced by the cable when conventional test probes move.

[0006] To achieve the above objectives, the specific solution of the present invention is as follows: It includes a semiconductor wafer; a light source array; a light source array control module; a receiving antenna; a signal receiving and processing device; and a host control module.

[0007] When the semiconductor chip is irradiated by light, plasma can be formed in the irradiated area to scatter the electromagnetic wave to be measured, and the semiconductor chip is placed in the spatial region of the electromagnetic wave to be measured.

[0008] The light source array is fixed behind the semiconductor wafer, and the structured light emitted from the light source array can cover the semiconductor wafer to excite the semiconductor wafer to form a plasma array.

[0009] The light source array control module is connected to the light source array and is used to control the modulation frequency of each light source unit;

[0010] The receiving antenna is used to receive the electromagnetic signal to be measured;

[0011] The signal receiving and processing device is connected to the receiving antenna and is used to receive and process signals;

[0012] The upper-level control module is connected to the signal receiving device and the light source array control module, and is used to send commands to control the light source array control module and the signal receiving device to realize the signal acquisition of the electromagnetic wave distribution to be measured.

[0013] The semiconductor wafer has a photoconductive effect, and plasma is formed in the irradiated area after being illuminated; its shape can be prepared as a plane or a curved surface according to the requirements of the area to be tested.

[0014] The light source array is in a two-dimensional distribution form. The light wavelength of the light source array unit is selected from the wavelength range that can excite the semiconductor wafer to generate plasma. The form of the light source array includes, but is not limited to, fiber laser array, semiconductor laser array, projector and other spatial light source array forms.

[0015] The light source array control module includes a modulation unit group, each modulation unit controls the modulation frequency of the light source array unit, which can simultaneously control each light source array unit to work at a different modulation frequency.

[0016] The signal receiving and processing device can be a broadband swept-frequency signal receiver or a parallel multi-channel signal receiver, which can quickly receive and process signals to achieve fast, near real-time measurement.

[0017] The steps for measuring electromagnetic field distribution using this system are as follows:

[0018] Step 1: Place the semiconductor wafer in the area to be tested;

[0019] Step 2: Set the modulation frequency of each light source array unit through the host control module;

[0020] Step 3: The host control module sends instructions to set the parameters of the signal receiving and processing device, receives the signal after the frequency difference between the frequency to be measured and each modulation frequency, and completes the test of the amplitude and phase distribution of electromagnetic waves in the space region to be measured.

[0021] The beneficial effects of this invention are as follows: Compared with existing measurement technologies, the measurement system of this invention has a simple structure, uses plasma as an "equivalent probe," and avoids the influence of additional fixtures on the test area introduced when using conventional probes; it replaces the conventional spatial scanning sampling test scheme with a light source array arrangement, improving test efficiency; the "equivalent probe" has a fixed position, eliminating the need for a mechanical scanning structure, ensuring positioning accuracy, and improving test accuracy; the receiving antenna and RF cable have fixed positions during the test, avoiding measurement errors introduced by cable movement during conventional probe scanning tests. This invention is a fast and accurate method for measuring electromagnetic wave vector distribution. Attached Figure Description

[0022] Figure 1 This is a multi-frequency parallel modulation scattering electromagnetic wave vector distribution measurement system according to the first embodiment of the present invention;

[0023] Figure 1 Explanation of reference numerals in the attached figures:

[0024] 1-Semiconductor wafer; 2-Light source array; 3-Light source array control module; 4-Upper control module; 5-Signal receiving and processing device; 6-Receiving antenna; 7-Light source array unit; 8-Plasma array; 9-Signal of the electromagnetic wave under test after being modulated and scattered by the light source array; 10-Electromagnetic wave under test; 11-Light source array beam. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this is not to limit the scope of the invention to this.

[0026] like Figure 1 As shown, the fast electromagnetic wave measurement system based on modulation scattering in this embodiment includes: a semiconductor chip 1 for generating plasma to scatter the electromagnetic wave to be measured; a light source array 2 for irradiating the semiconductor chip to excite and generate plasma; a light source array control module 3 for controlling the modulation frequency of each unit in the light source array; a receiving antenna 6 for receiving the scattered electromagnetic wave; a signal receiving and processing device 5 for receiving and processing the scattered electromagnetic signal; and a host control module 4 for sending commands to control the light source array control module and the signal receiving and processing device.

[0027] like Figure 1 As shown, when the fast electromagnetic wave measurement system based on modulation scattering is working, for the measurement of the electromagnetic wave 10 to be measured at frequency f0, the measurement spatial position should first be determined. The semiconductor chip 1 is placed at the measurement position. In particular, semiconductor chips 1 of different shapes can be prepared according to the testing requirements to achieve electromagnetic wave distribution measurements on planes, curved surfaces, etc.

[0028] Specifically, the light source array 2 is placed behind the semiconductor chip 1. The light source array 2 consists of m rows and n columns of identical light source array units 7. In this embodiment, the light source array uses a fiber laser array with an adaptive focusing lens. Alternatively, a semiconductor laser array, a projector, or other spatial light source array can also be used.

[0029] Each light source array unit is numbered l ij (i = 1, 2, ... m; j = 1, 2, ... n). In particular, the arrangement of the light source array can be arranged into other shapes according to sampling requirements.

[0030] The host control module 4 sends instructions to the light source array control module 3, causing the light source control module 3 to set the modulation frequency f of each light source array unit. ij .

[0031] The light source array units operating at different modulation frequencies irradiate the semiconductor chip 1, and the array irradiation beam 11 irradiates the semiconductor chip 1 to form a plasma array 8 with different modulation frequencies.

[0032] The plasma element in the i-th row and j-th column scatters the electromagnetic wave to be measured 10, and the electromagnetic wave signal s after plasma scattering is... ij It can be expressed as follows:

[0033]

[0034] Among them, A 0ij , A represents the amplitude and phase information of the electromagnetic wave to be measured at the position of the plasma unit in the i-th row and j-th column, respectively. ij Let A represent the amplitude information introduced by the modulation of the plasma unit in the i-th row and j-th column, where t is time. Assuming the semiconductor sheet is uniform and the light intensity amplitude of the light source array units is consistent, therefore A... ij To match the amplitude information A of the field to be measured 0ij The relevant parameter rA 0ij , where r is a constant related to plasma properties. Therefore, equation (1) can be further expressed as:

[0035]

[0036] This formula illustrates that the electromagnetic wave signal after modulation and scattering of the electromagnetic wave 10 carries an electromagnetic signal with a frequency difference from the modulation frequency. Electromagnetic signal 9 represents the difference frequency signal between the measured frequency and the modulation frequency of the electromagnetic wave 10 after modulation and scattering by the plasma array 8. This difference frequency signal can be expressed as:

[0037]

[0038] This formula indicates that the difference frequency signal in the electromagnetic signal 9 modulated and scattered by the plasma array 8 is a broadband signal, and different frequencies represent the amplitude and phase information of the electromagnetic wave 10 to be measured at different positions.

[0039] After the broadband signal is received by the receiving antenna 6, the receiving frequency range of the signal receiving and processing device 5 can be set by the upper control module 4 to obtain the amplitude and phase spatial distribution of the electromagnetic wave 10 to be measured. The electromagnetic wave amplitude and phase signals of different frequencies represent the electromagnetic wave amplitude and phase signals at different spatial locations in the area to be measured. If the signal receiving device 5 is a parallel multi-channel receiving device, different channels can simultaneously receive electromagnetic wave vector signals of different frequencies, and real-time electromagnetic wave vector distribution measurement can be realized.

Claims

1. A multi-frequency parallel modulated scattered electromagnetic wave vector distribution measurement system, characterized by: The application relates to a semiconductor chip, a light source array, a light source array control module, a receiving antenna, a signal receiving and processing device and an upper control module. The semiconductor chip has a photoconductive effect, and after the semiconductor chip is irradiated by light, a plasmonic scattering electromagnetic wave can be formed in an irradiated area; the semiconductor chip is placed in a space area of the electromagnetic wave to be measured; The light source array is fixed behind the semiconductor chip, and structured light emitted by the light source array can cover the semiconductor chip and be used for exciting the semiconductor chip to form a plasmonic array; The light source array control module is connected with the light source array and is used for controlling the modulation frequency of each light source unit; The receiving antenna is used for receiving the electromagnetic signal to be measured; The signal receiving and processing device is connected with the receiving antenna and is used for receiving and processing signals; The upper control module is connected with the signal receiving and processing device and the light source array control module, is used for sending instructions to control the light source array control module and the signal receiving and processing device, and realizes vector signal collection of the spatial distribution of the electromagnetic wave to be measured.

2. The multi-frequency parallel modulation scattered electromagnetic wave vector distribution measurement system according to claim 1, characterized in that: The semiconductor chip can be prepared as a plane or a curved surface according to the requirement of a measured area.

3. The multi-frequency parallel modulated scattered electromagnetic wave vector distribution measurement system according to claim 1, wherein: The light source array is in a two-dimensional distribution form, the light source array is composed of m rows and n columns of same light source array units, the wavelength of the light source array unit is selected to be in a wavelength range capable of exciting the semiconductor chip to generate a plasmonic, and the form of the light source array includes a fiber laser array, a semiconductor laser array or a projector light source array.

4. The multi-frequency parallel modulated scattered electromagnetic wave vector distribution measurement system according to claim 1, characterized in that: The light source array control module comprises modulation units, each modulation unit controls the modulation frequency of the light source array unit, and each light source array unit can work at different modulation frequencies.

5. The multi-frequency parallel modulation scattered electromagnetic wave vector distribution measurement system according to claim 1, characterized in that: The signal receiving and processing device can be a broadband sweep signal receiver or a parallel multi-channel signal receiver.

6. The measurement method of a multi-frequency parallel modulation scattered electromagnetic wave vector distribution measurement system according to claim 1, characterized in that, The application further discloses a method for measuring electromagnetic wave spatial distribution, comprising the following steps: Step 1: placing the semiconductor chip in a measured area; Step 2: setting the modulation frequency of each light source array unit through the upper control module; Step 3: sending instructions by the upper control module to set the parameters of the signal receiving and processing device, receiving signals after the difference frequency between the measured frequency and each modulation frequency, and completing the test of the amplitude and phase distribution of the electromagnetic wave in the measured space area.

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