An ECV method semiconductor carrier concentration measuring device

Abstract

The utility model relates to a carrier concentration detection device, especially a kind of ECV method semiconductor carrier concentration measuring device, comprising: electrochemical etching unit, is equipped with the etching hole for being pressed on silicon chip to etch silicon chip along the thickness direction;Detection unit, be located on the electrochemical etching unit, the detection unit carries out carrier concentration detection after each etching is completed;Liquid path unit, with the electrochemical etching unit is connected, for providing electrolyte and cleaning fluid;Optical unit, with the etching hole is opposite and is arranged, for N type semiconductor etching when passing through light illumination produces electron hole pair;And main control unit, respectively with the electrochemical etching unit, detection unit, liquid path unit and optical unit connection.The utility model provides a kind of ECV method semiconductor carrier concentration measuring device, and the carrier concentration of silicon chip is detected layer by layer using the mode of etching, obtains the carrier concentration curve under different etching depths.

Description

Technical Field

[0001] This utility model relates to a carrier concentration detection device, and more particularly to an ECV method semiconductor carrier concentration measurement device. Background Technology

[0002] Charge carriers are microscopic particles in a silicon wafer that can carry electrical charge and generate current. If metal electrodes and wires are connected to the P-region and N-region, and a load (such as a light bulb) is connected, then holes in the P-region and electrons in the N-region will recombine through the external circuit: electrons start from the N-region, flow through the external circuit, do work, and then reach the P-region to recombine with holes. This forms a continuous current flowing from the P-region through the load to the N-region, i.e., the photocurrent. The charge carrier concentration is directly related to the photoelectric conversion efficiency and directly affects the efficiency of the solar cell; therefore, it is necessary to detect the charge carrier concentration.

[0003] For example, CN105915179A discloses a photoinduced carrier radiation phase-locked imaging detection method and system for wafers and solar cells. Based on the principle of photoinduced carrier radiation detection, it includes a near-infrared camera, a signal acquisition card (with analog signal output function), a computer, a three-dimensional moving stage, a long-pass filter, a first laser, and a second laser. The sample under test is fixed on the three-dimensional moving stage, which is adjusted to make the sample clearly visible within the field of view of the near-infrared camera. The computer controls the signal acquisition card to generate a modulation signal. This signal controls the first and second lasers to be synchronously triggered and photoexcite the sample under test. After the two laser beams irradiate the sample, they generate carrier radiation photon signals. Simultaneously, the near-infrared camera synchronously acquires the image sequence generated by the carrier radiation photon signals. Laser beams reflected by the sample and environmental noise signals are filtered out by the long-pass filter. The near-infrared camera feeds back the acquired image sequence to the computer, which performs phase-locked correlation processing on the acquired image sequence to detect the carrier radiation signal.

[0004] Although this detection system can improve detection efficiency, it can only detect the carrier concentration on the surface of the silicon wafer and cannot detect the carrier concentration inside. Utility Model Content

[0005] To address the aforementioned problems, this utility model provides an ECV method semiconductor carrier concentration measurement device, the specific technical solution of which is as follows: An ECV (Electrochemical Carrier Concentration Measurement) device for semiconductors includes: an electrochemical etching unit with etching holes for etching the silicon wafer along its thickness direction; a detection unit disposed on the electrochemical etching unit, wherein the detection unit detects the carrier concentration after each etching operation; a liquid circuit unit connected to the electrochemical etching unit for providing electrolyte and cleaning solution; an optical unit disposed opposite to the etching holes for generating electron-hole pairs by illumination during N-type semiconductor etching; and a main control unit connected to the electrochemical etching unit, the detection unit, the liquid circuit unit, and the optical unit.

[0006] Preferably, the electrochemical etching unit includes: a reaction tank with a reaction chamber communicating with the etching hole, the reaction chamber being connected to the liquid circuit unit; a first pair of electrodes disposed in the reaction chamber; a first working electrode resting on the silicon wafer; and an etching control component connected to the main control unit, the first pair of electrodes, and the first working electrode, respectively, for controlling the etching voltage and measuring the etching current in the etching circuit to control the etching depth.

[0007] Furthermore, the etching control component includes: an etching power supply module connected to the first pair of electrodes and the first working electrode; and an etching current sampling module connected to the etching power supply module, the first pair of electrodes, and the first working electrode, respectively.

[0008] Furthermore, the electrochemical etching unit also includes a sealing element, which is disposed on the reaction tank and has etching holes for pressing against the silicon wafer.

[0009] Furthermore, the detection unit includes: a second working electrode resting against a silicon wafer; a second pair of electrodes disposed within the reaction chamber; and a reference electrode disposed within the reaction chamber; the second working electrode, the second pair of electrodes, and the reference electrode are all connected to the main control unit.

[0010] Preferably, the liquid circuit unit includes: a peristaltic pump connected to the main control unit and the electrochemical etching unit; a three-way valve connected to the main control unit and the peristaltic pump; an electrolyte module connected to the three-way valve; a cleaning fluid module connected to the three-way valve; a waste liquid module connected to the three-way valve; and an outlet valve connected to the electrochemical etching unit, the waste liquid module, and the main control unit, respectively.

[0011] Preferably, the optical unit includes an etching light source, which is disposed opposite to the etching hole.

[0012] Furthermore, the optical unit also includes a camera, which is disposed opposite to the etched hole.

[0013] Furthermore, the etching light source includes a halogen lamp, an LED lamp, or an ultraviolet lamp.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The ECV method semiconductor carrier concentration measurement device provided by this invention uses etching to detect the carrier concentration of silicon wafers layer by layer, and obtains carrier concentration curves at different etching depths. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of this application; Figure 2 This is a schematic diagram of the liquid circuit unit and optical unit of this application; Figure 3 This is a schematic diagram of the detection unit, electrochemical etching unit, and optical unit of this application. Detailed Implementation

[0016] The present invention will now be further described with reference to the accompanying drawings.

[0017] like Figures 1 to 3 As shown, an ECV method semiconductor carrier concentration measurement device includes a main control unit, an electrochemical etching unit, a detection unit, a liquid circuit unit, and an optical unit, all connected to the main control unit. The electrochemical etching unit has etching holes and is used to etch the silicon wafer along its thickness direction. The detection unit is located on the electrochemical etching unit and performs carrier concentration detection after each etching operation. The liquid circuit unit is connected to the electrochemical etching unit and is used to provide electrolyte and cleaning solution. The optical unit is positioned opposite the etching holes and is used to generate electron-hole pairs through illumination during N-type semiconductor etching.

[0018] The electrochemical etching unit includes a reaction tank, a first pair of electrodes, a first working electrode, and an etching control assembly. The reaction tank has a reaction chamber inside, which communicates with the etching holes and is connected to the liquid circuit unit. The first pair of electrodes is mounted on the reaction tank, with its ends located inside the reaction chamber. The first working electrode is used to press against the silicon wafer. The etching control assembly is connected to the main control unit, the first pair of electrodes, and the first working electrode, respectively, and is used to control the etching voltage and measure the etching current in the etching circuit to control the etching depth.

[0019] To enhance the seal between the reaction tank and the silicon wafer, the electrochemical etching unit also includes a seal. The seal is located on the reaction tank and has etching holes. The seal rests against the silicon wafer, achieving a seal between the reaction tank and the silicon wafer. The seal can be made of rubber.

[0020] The etching control assembly includes an etching power supply module and an etching current sampling module. The etching power supply module is connected to the first pair of electrodes and the first working electrode. The etching current sampling module is connected to the etching power supply module, the first pair of electrodes, and the first working electrode. The etching power supply module is also connected to the main control unit.

[0021] The detection unit includes a second working electrode, a second pair of electrodes, and a reference electrode. The second working electrode rests against the silicon wafer. The second pair of electrodes is mounted on the reaction tank, with its ends inserted into the reaction chamber. The reference electrode is mounted on the reaction tank, with its ends inserted into the reaction chamber. The second working electrode, the second pair of electrodes, and the reference electrode are all connected to the main control unit.

[0022] Etching process: The current output by the etching power module passes through the first pair of electrodes, the electrolyte, and the first working electrode to form an etching circuit. The etching rate can be controlled by setting the voltage, and the etching depth can be calculated by measuring the current in the circuit.

[0023] CV measurement: The electrochemical three-electrode system consisting of the second working electrode, the reference electrode, and the second pair of electrodes can be used to obtain the Mott-Sckottky curve by performing CV measurement on the system through the main control unit. The current carrier concentration can be calculated from this curve.

[0024] By alternating the etching and CV measurement processes during electrochemical measurement, carrier concentration curves at different etching depths can be obtained.

[0025] The liquid circuit unit includes a peristaltic pump, a three-way valve, an electrolyte module, a cleaning fluid module, a waste liquid module, and an outlet valve. The peristaltic pump is connected to the main control unit, the reaction tank, and the three-way valve. The three-way valve is also connected to the main control unit, the electrolyte module, the cleaning fluid module, and the waste liquid module. The electrode fluid module includes an electrolyte tank and electrode fluid contained within it. The electrolyte tank is connected to the acid supply port of the three-way valve via a pipeline. The cleaning fluid module includes a cleaning fluid tank and cleaning fluid contained within it. The cleaning tank is connected to the cleaning port of the three-way valve via a pipeline. The waste liquid module includes a waste liquid tank, which is connected to the outlet valve and the drain port of the three-way valve via pipelines. The outlet valve is connected to the reaction chamber via a pipeline and is used to control the connection between the reaction chamber and the waste liquid tank.

[0026] The optical unit includes an etching light source and a camera, both connected to the main control unit, with both positioned opposite the etching holes. The etching light source includes a halogen lamp, an LED lamp, or an ultraviolet lamp. The camera is used to detect the etching process, enabling the main control unit to control the etching light source.

[0027] To perform N-type semiconductor etching, the light in the optical unit needs to be turned on during the etching stage to generate electron-hole pairs through illumination.

[0028] During the etching preparation stage, the silicon wafer is pressed firmly onto the sealing element, and both the first and second working electrodes are in contact with the silicon wafer to ensure conductivity.

[0029] During the etching start-up loading phase, the main control unit controls the three-way valve to open the acid supply channel, and the main control unit controls the peristaltic pump to work, and the peristaltic pump pumps the acid into the reaction chamber. During the interval between the etching reaction and CV measurement, the main control unit controls the peristaltic pump to pump a small amount of electrolyte in to eliminate bubbles generated by the reaction between the electrolyte and the semiconductor contact site. At the end stage, the main control unit controls the liquid outlet valve to open, discharging the liquid in the reaction chamber into the waste liquid tank. After the discharge is completed, the cleaning fluid channel of the three-way valve is opened, and the cleaning fluid is pumped into the reaction chamber by the peristaltic pump. The cleaning fluid cleans the pipeline and the reaction chamber. After the discharge is completed, the liquid outlet valve is opened to discharge the cleaning fluid, thus completing the entire test process.

[0030] The technical principles of this utility model have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of this utility model and should not be construed as limiting the scope of protection of this utility model in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of this utility model without inventive effort, and these embodiments will all fall within the protection scope of the claims of this utility model.

Claims

1. A semiconductor carrier concentration measurement device using the ECV method, characterized in that, include: The electrochemical etching unit is provided with etching holes for etching the silicon wafer along the thickness direction by pressing against the silicon wafer; A detection unit is provided on the electrochemical etching unit, and the detection unit performs carrier concentration detection after each etching is completed; The liquid circuit unit, connected to the electrochemical etching unit, is used to provide electrolyte and cleaning solution; An optical unit, disposed opposite to the etching hole, is used to generate electron-hole pairs by illumination during N-type semiconductor etching. as well as The main control unit is connected to the electrochemical etching unit, the detection unit, the liquid circuit unit, and the optical unit, respectively.

2. The ECV method semiconductor carrier concentration measurement device according to claim 1, characterized in that, The electrochemical etching unit includes: The reaction tank is provided with a reaction chamber communicating with the etched hole, and the reaction chamber is connected to the liquid circuit unit; The first pair of electrodes is disposed inside the reaction chamber; The first working electrode rests against the silicon wafer; The etching control component is connected to the main control unit, the first pair of electrodes and the first working electrode, respectively, and is used to control the etching voltage and measure the etching current in the etching circuit to control the etching depth.

3. The ECV method semiconductor carrier concentration measurement device according to claim 2, characterized in that, The etching control component includes: Etching power module, connected to the first pair of electrodes and the first working electrode; The etching current sampling module is connected to the etching power supply module, the first pair of electrodes, and the first working electrode, respectively.

4. The ECV method semiconductor carrier concentration measurement device according to claim 2, characterized in that, The electrochemical etching unit further includes a sealing element, which is disposed on the reaction tank and has etching holes for pressing against the silicon wafer.

5. The ECV method semiconductor carrier concentration measurement device according to claim 2, characterized in that, The detection unit includes: The second working electrode rests against the silicon wafer; The second pair of electrodes is disposed inside the reaction chamber; A reference electrode is disposed within the reaction chamber; The second working electrode, the second pair of electrodes, and the reference electrode are all connected to the main control unit.

6. The ECV method semiconductor carrier concentration measurement device according to claim 1, characterized in that, The fluid circuit unit includes: A peristaltic pump is connected to the main control unit and the electrochemical etching unit; A three-way valve is connected to the main control unit and the peristaltic pump; The electrolyte module is connected to the three-way valve; The cleaning fluid module is connected to the three-way valve; Waste liquid module, connected to the three-way valve; and The liquid outlet valve is connected to the electrochemical etching unit, the waste liquid module, and the main control unit, respectively.

7. The ECV method semiconductor carrier concentration measurement device according to claim 1, characterized in that, The optical unit includes an etching light source, which is disposed opposite to the etching hole and connected to the main control unit.

8. The ECV method semiconductor carrier concentration measurement device according to claim 7, characterized in that, The optical unit further includes a camera, which is disposed opposite to the etched hole and connected to the main control unit.

9. The ECV method semiconductor carrier concentration measurement device according to claim 7, characterized in that, The etching light source includes halogen lamps, LED lamps, or ultraviolet lamps.

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