阅读说明：本技术 一种表征碲镉汞红外探测器电极沉积损伤的方法 (Method for representing electrode deposition damage of mercury cadmium telluride infrared detector ) 是由 何斌 刘明 宁提 祁娇娇 陈书真 于 2021-08-27 设计创作，主要内容包括：本发明公开了一种表征碲镉汞红外探测器电极沉积损伤的方法,本发明所述方法能够有效对预设碲镉汞芯片的电极沉积损伤进行表征,从而优化电极生长条件,减少电极沉积损伤,最终提高了碲镉汞红外探测器的性能。(The invention discloses a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector, which can effectively represent the electrode deposition damage of a preset mercury cadmium telluride chip, thereby optimizing the growth condition of an electrode, reducing the electrode deposition damage and finally improving the performance of the mercury cadmium telluride infrared detector.)

1. A method for characterizing electrode deposition damage of a mercury cadmium telluride infrared detector is characterized by comprising the following steps:

measuring the carrier concentration of a preset mercury cadmium telluride chip before metal deposition, wherein the preset mercury cadmium telluride chip is an n-type mercury cadmium telluride chip or a p-type mercury cadmium telluride chip;

growing a metal electrode on the whole surface of the preset HgCdTe chip, and measuring the carrier concentration of the preset HgCdTe chip after metal deposition;

and judging whether the change increment of the carrier concentration of the preset mercury cadmium telluride chip after metal deposition and the carrier concentration before metal deposition is larger than a preset concentration threshold value or not, if so, judging that the electrode deposition damage of the preset mercury cadmium telluride chip is too large, and influencing the device processing technology of the preset mercury cadmium telluride chip.

2. The method of claim 1, wherein before the step of determining the carrier concentration of the predetermined HgCdTe chip before the step of depositing the metal, the method further comprises the steps of:

and preprocessing the preset mercury cadmium telluride chip, and testing the preprocessed preset mercury cadmium telluride chip.

3. The method of claim 2, wherein the pre-treating the predetermined HgCdTe chip comprises:

and cleaning the preset mercury cadmium telluride chip and drying.

4. The method of claim 2, wherein the testing of the pre-treated HgCdTe chip comprises:

and welding the electrodes to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrodes meets the preset contact requirement.

5. The method of claim 1, wherein the step of measuring the carrier concentration of the predetermined HgCdTe chip before the metal deposition comprises:

and measuring the carrier concentration of the whole preset mercury cadmium telluride chip before metal deposition by a Van der Bao method.

6. The method according to any one of claims 1 to 5, wherein after the metal electrode is grown on the whole surface of the preset HgCdTe chip, before the carrier concentration of the preset HgCdTe chip after metal deposition is measured, the method further comprises:

and stripping the metal electrode by using a chemical method, welding the metal electrode to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrode meets the preset contact requirement.

7. The method of claim 6, wherein chemically stripping the metal electrode comprises:

removing the electrode by stripping the metal with concentrated HCl or by using a metal corrosive liquid.

8. The method of claim 6, wherein the soldering to four corners of the predetermined HgCdTe chip by wires and the testing of the predetermined HgCdTe chip comprise:

and welding four corners of the preset HgCdTe chip through leads, ensuring that the welding position of the leads is consistent with the welding position before metal deposition, and the linear contact of the electrodes meets the preset contact requirement, and then testing the preset HgCdTe chip.

9. The method of claim 6, wherein measuring the carrier concentration of the predetermined HgCdTe chip after depositing the metal comprises:

and measuring the carrier concentration of the preset mercury cadmium telluride chip after metal deposition by a Van der Bao method.

10. The method of claim 6, further comprising:

and setting the preset concentration threshold according to the historical statistics of the blind pixel data of the mercury cadmium telluride chip under the deposition damage.

Technical Field

The invention relates to the technical field of semiconductors, in particular to a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector.

Background

The development of infrared focal plane detectors is so far, mercury cadmium telluride is in the mainstream status in the technical field of infrared detectors, the mercury cadmium telluride infrared detector covers the whole infrared band from short wave to very long wave (1-16 mu m), and each band shows better performance. The photocurrent formed by the large-scale pn junction array is transmitted to a reading circuit through the metal electrode to complete signal conversion. In the signal conversion process of the detector, the device with larger electrode deposition damage has poorer contact performance, and is often accompanied by larger current noise, so that the pixel has no response signal or has small response signal, and the pixel is judged as a blind pixel. Therefore, how to detect the electrode deposition damage becomes a problem to be solved urgently.

Disclosure of Invention

The invention provides a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector, which aims to solve the problem that the electrode deposition damage cannot be well represented in the prior art.

The invention provides a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector, which comprises the following steps: measuring the carrier concentration of a preset mercury cadmium telluride chip before metal deposition, wherein the preset mercury cadmium telluride chip is an n-type mercury cadmium telluride chip or a p-type mercury cadmium telluride chip;

growing a metal electrode on the whole surface of the preset HgCdTe chip, and measuring the carrier concentration of the preset HgCdTe chip after metal deposition;

and judging whether the change increment of the carrier concentration of the preset mercury cadmium telluride chip after metal deposition and the carrier concentration before metal deposition is larger than a preset concentration threshold value or not, if so, judging that the electrode deposition damage of the preset mercury cadmium telluride chip is too large, and influencing the device processing technology of the preset mercury cadmium telluride chip.

Optionally, before the determining the carrier concentration of the preset mercury cadmium telluride chip before the metal is not deposited, the method further includes: and preprocessing the preset mercury cadmium telluride chip, and testing the preprocessed preset mercury cadmium telluride chip.

Optionally, the preprocessing the preset mercury cadmium telluride chip includes: and cleaning the preset mercury cadmium telluride chip and drying.

Optionally, the testing of the pretreated mercury cadmium telluride chip includes: and welding the electrodes to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrodes meets the preset contact requirement.

Optionally, the determining the carrier concentration of the preset mercury cadmium telluride chip before metal deposition includes:

and measuring the carrier concentration of the whole preset mercury cadmium telluride chip before metal deposition by a Van der Bao method.

Optionally, after growing a metal electrode on the entire surface of the preset mercury cadmium telluride chip, before measuring the carrier concentration of the preset mercury cadmium telluride chip after depositing the metal, the method further includes: and stripping the metal electrode by using a chemical method, welding the metal electrode to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrode meets the preset contact requirement.

Optionally, the chemically stripping the metal electrode includes: removing the electrode by stripping the metal with concentrated HCl or by using a metal corrosive liquid.

Optionally, the welding of the lead wires to four corners of the preset mercury cadmium telluride chip and the testing of the preset mercury cadmium telluride chip include: and welding four corners of the preset HgCdTe chip through leads, ensuring that the welding position of the leads is consistent with the welding position before metal deposition, and the linear contact of the electrodes meets the preset contact requirement, and then testing the preset HgCdTe chip.

Optionally, measuring the carrier concentration of the preset mercury cadmium telluride chip after metal deposition includes: and measuring the carrier concentration of the preset mercury cadmium telluride chip after metal deposition by a Van der Bao method.

Optionally, the preset concentration threshold is set according to historical blind pixel data statistics of the mercury cadmium telluride chip under deposition damage.

Optionally, the preset concentration threshold is 10%.

The invention has the following beneficial effects:

the method can effectively characterize the electrode deposition damage of the preset HgCdTe chip, thereby optimizing the electrode growth condition, reducing the electrode deposition damage and finally improving the performance of the HgCdTe infrared detector.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic flow chart of a method for characterizing electrode deposition damage of a mercury cadmium telluride infrared detector provided by an embodiment of the invention;

FIG. 2 is a schematic flow chart of another method for characterizing mercury cadmium telluride infrared detector electrode deposition damage provided by the embodiment of the invention;

FIG. 3 is a position diagram of four electrodes on the HgCdTe surface soldered by indium pressing method in the embodiment of the invention;

fig. 4 is a schematic diagram of the change of the carrier concentration of four groups of samples before and after electrode deposition in the embodiment of the present invention.

Detailed Description

Aiming at the problem that the electrode deposition damage cannot be well characterized in the prior art, the embodiment of the invention provides a method for characterizing the electrode deposition damage, so that the electrode growth condition is optimized, and the electrode deposition damage is reduced. The present invention will be described in further detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The embodiment of the invention provides a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector, and the method comprises the following steps of:

s101, measuring the carrier concentration of a preset mercury cadmium telluride chip before metal deposition, wherein the preset mercury cadmium telluride chip is an n-type mercury cadmium telluride chip or a p-type mercury cadmium telluride chip;

in specific implementation, before step S101, the method further includes: and preprocessing the preset mercury cadmium telluride chip, and testing the preprocessed preset mercury cadmium telluride chip.

Wherein, the preprocessing is carried out on the preset HgCdTe chip, and the preprocessing comprises the following steps:

and cleaning the preset mercury cadmium telluride chip and drying.

Testing the pretreated mercury cadmium telluride chip, comprising:

and welding the electrodes to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrodes meets the preset contact requirement. Specifically, the lead wires are welded at four corners of the mercury cadmium telluride surface, and a semiconductor parameter tester is adopted to observe electrode contact, so that the linearity is required to be more than 0.99.

S102, growing a metal electrode on the whole surface of the preset HgCdTe chip, and measuring the carrier concentration of the preset HgCdTe chip after metal deposition;

in specific implementation, after growing a metal electrode on the entire surface of the preset mercury cadmium telluride chip, before measuring the carrier concentration of the preset mercury cadmium telluride chip after depositing metal, the method further includes: and stripping the metal electrode by using a chemical method, welding the metal electrode to four corners of the preset HgCdTe chip through leads, and testing the preset HgCdTe chip to determine that the linear contact of the electrode meets the preset contact requirement.

Specifically, the embodiment of the invention utilizes concentrated HCl to make metal fall off or metal corrosive liquid to remove the electrode.

And the embodiment of the invention is to weld four corners of the preset HgCdTe chip through leads, ensure that the welding position of the leads is consistent with the welding position before metal deposition, and the linear contact of the electrodes meets the preset contact requirement, and then test the preset HgCdTe chip.

S103, judging whether the change increment of the carrier concentration of the preset HgCdTe chip after metal deposition and the carrier concentration of the preset HgCdTe chip before metal deposition is larger than a preset concentration threshold value or not, and if so, judging that the electrode deposition damage of the preset HgCdTe chip is too large, which can influence the device processing technology of the preset HgCdTe chip.

In specific implementation, the preset concentration threshold is set according to historical blind pixel data statistics of the mercury cadmium telluride chip under deposition damage. For example, the preset concentration threshold is set to 10%. Of course, those skilled in the art can set other preset concentration thresholds according to actual needs, and the present invention is not limited in this regard.

It should be noted that in the embodiment of the present invention, P-type or n-type mercury cadmium telluride is prepared by liquid phase epitaxy, and the metal electrode can be three common metal electrode materials of Cr, Au, and Pt for the mercury cadmium telluride infrared detector. Growing a metal electrode by using ion beam deposition equipment, wherein the beam voltage range is as follows: 300V-1500V, beam current 100 mA-400 mA, and the chemical method comprises the steps of enabling metal to fall off by concentrated HCl or removing an electrode by metal corrosive liquid.

The method according to an embodiment of the invention is explained and illustrated in detail in two specific embodiments in conjunction with fig. 2, 3 and 4 below:

example 1

The embodiment of the invention provides a method for representing electrode deposition damage of a mercury cadmium telluride infrared detector, which is used for optimizing the growth condition of an electrode and reducing the electrode deposition damage in the metallization process of the mercury cadmium telluride infrared detector.

1. Selecting an N-type or p-type tellurium-cadmium-mercury chip, cleaning the surface of the material by sequentially adopting acetone and alcohol, and then drying the chip by using an N2 air gun;

2. welding the lead wires to four corners of the mercury cadmium telluride surface, and observing electrode contact by using a semiconductor parameter tester, wherein the linearity is required to be more than 0.99;

3. measuring the carrier concentration of the whole p-type mercury cadmium telluride chip before metal deposition by adopting a Van der Bao method; removing the lead and In after testing;

4. growing a metal electrode on the whole surface of the mercury cadmium telluride chip by adopting an ion beam deposition technology;

5. stripping the metal electrode by a chemical method, wherein the step of stripping comprises the step of stripping metal by concentrated HCl or removing the electrode by metal corrosive liquid;

6. welding the lead wires to four corners of the mercury cadmium telluride surface by using In balls, ensuring that the welding position is consistent with the previous position, observing electrode contact by using a semiconductor parameter tester, and requiring the linearity to be more than 0.99;

7. measuring the carrier concentration of the whole p-type mercury cadmium telluride chip after metal deposition by adopting a Van der Bao method;

8. comparing the carrier concentration change of the p-type tellurium-cadmium-mercury chip before and after metal deposition; when the increment of the change of the carrier concentration is larger than 10 percent of the carrier concentration before metal deposition, the damage of electrode deposition can be considered to be large, and the device processing technology is seriously influenced.

Example 2

As shown in fig. 2, a method for characterizing electrode deposition damage of a mercury cadmium telluride infrared detector provided by an embodiment of the present invention includes:

s101, selecting four groups of samples of a p-type mercury cadmium telluride chip a, b, c and d, representing the mercury cadmium telluride thickness by adopting a Fourier thickness tester, sequentially cleaning the surface of a material by adopting acetone and alcohol, and finally cleaning the surface of the material by using N₂And drying the chip by an air gun. The thickness refers to the thickness of the p-type tellurium-cadmium-mercury after the substrate is removed, and the thickness parameter of the material needs to be obtained in the Van der Bao method test; and organic matters possibly existing on the surface of the material are removed by adopting acetone and alcohol, so that the stability of the subsequent In ball lead welding is enhanced.

S102, as shown in FIG. 3, in the embodiment of the invention, the lead is welded on the mercury cadmium telluride surface by an indium pressing method, and the four electrode positions keep highly symmetrical; setting the welding temperature to be 160-170 ℃, and welding the prepared In balls on four corners of mercury cadmium telluride by using an electric soldering iron; and welding the other ends of the four leads to a sample card, placing the sample card into a liquid nitrogen chamber of an IV test system, adding high-purity liquid nitrogen into the liquid nitrogen chamber until the distance between the high-purity liquid nitrogen and the liquid nitrogen chamber is about 1cm, and waiting for 5 minutes to keep the liquid level stable. And observing electrode contact by using a semiconductor parameter tester at 77K, wherein the contact linearity of all the electrodes in the current test reaches more than 0.99. The van der waals method also requires that the electrode contact must be a good ohmic contact, and the linearity of the resulting IV curve of the connection method such as 1212,1313,1414,2323,2424,3434 must be observed using a semiconductor parameter instrument before hall tests are performed; the electrode contact at 77K was tested because of the practical use temperature of the mercury cadmium telluride infrared detector.

S103, measuring the carrier concentration of the whole p-type mercury cadmium telluride chip before metal deposition by adopting a Van der Bao method under 77K; wherein the concentration of the a group carrier is 5.1 × 10¹⁷/cm³B group carrier concentration 5.3X 10¹⁷/cm³C group carrier concentration 4.8X 10¹⁷/cm³And d group carrier concentration 5.5X 10¹⁷/cm³(ii) a And uniformly removing the lead and In on the mercury cadmium telluride surface after testing.

The embodiment of the invention adopts a low-temperature Hall test system, and the Hall test conditions are selected as follows: 100uA to 100uA (step value of 50uA), 10KG to 10KG (step value of 10mG), and measuring to obtain the Hall coefficient (R) under the 77K changing magnetic field_H) And the conductivity type, the carrier concentration and the mobility of the mercury cadmium telluride material are obtained through later analysis of software.

And S104, growing a metal electrode Cr on the whole surface of the mercury cadmium telluride chip by using an ion beam deposition system. The four groups of chips use different beam current and beam voltage conditions in turn, wherein the beam current and the beam voltage are respectively 200mA/600V,200mA/8000V and 200mA/1000,200 mA/1200V; in order to maintain the thickness consistency of the metal electrode, the growth time of the four groups of chips a, b, c and d is not completely the same, and is 30min, 45min, 60min and 75min in sequence.

In the process of depositing the metal film by the ion beam, the beam pressure refers to the energy carried by inert gas ions emitted from an ion source, and the beam current refers to the number of ions emitted from the ion source per unit time and unit area.

S105, placing the chip into 50mL of concentrated HCl, soaking for 10min to enable the metal to automatically fall off, then washing for 2min with pure water, vertically aligning an alcohol spray gun to the chip at a pressure of 1Kg to remove possible stains, and finally observing the chip by using an optical microscope to ensure that the stains and the electrodes are removed completely.

In this embodiment, the chemical method may be to soak in concentrated HCl to make the metal fall off, or to directly corrode the metal electrode with a metal corrosive solution.

S106, welding the lead to the mercury cadmium telluride surface by using an indium pressing method, wherein the positions of four electrodes of each chip are kept consistent with those of S102; setting the welding temperature to be 160-170 ℃, and welding the prepared In balls on four corners of mercury cadmium telluride by using an electric soldering iron; and welding the other ends of the four leads to a sample card, placing the sample card into a liquid nitrogen chamber of an IV test system, adding high-purity liquid nitrogen into the liquid nitrogen chamber until the distance between the high-purity liquid nitrogen and the liquid nitrogen chamber is about 1cm, and waiting for 5 minutes to keep the liquid level stable. And observing electrode contact by using a semiconductor parameter tester at 77K, wherein the contact linearity of all the electrodes in the current test reaches more than 0.99.

S107, measuring the carrier concentration of the whole p-type mercury cadmium telluride chip after metal deposition by adopting a Van der Bao method under 77K; wherein the concentration of a group carrier is 5.3 × 10¹⁷/cm³B group carrier concentration 6.5X 10¹⁷/cm³C group carrier concentration 6.9X 10¹⁷/cm³D group carrier concentration 9.9X 10¹⁷/cm³(ii) a And uniformly removing the lead and In on the mercury cadmium telluride surface after testing.

The embodiment of the invention adopts a low-temperature Hall test system, and the Hall test conditions are selected as follows: 100uA to 100uA (step value of 50uA), 10KG to 10KG (step value of 10mG), and measuring to obtain the Hall coefficient (R) under the 77K changing magnetic field_H) And the conductivity type, the carrier concentration and the mobility of the mercury cadmium telluride material are obtained through later analysis of software.

S108, comparing the carrier concentration change of the p-type tellurium-cadmium-mercury chip before and after metal deposition. When the increment of the change of the carrier concentration is larger than 10 percent of the carrier concentration before metal deposition, the deposition damage is considered to be larger, and the influence on the device processing technology is larger. In the four experimental samples a, b, c and d shown in FIG. 4, the increment of the carrier concentration is Δ n_eIs sequentially 2 multiplied by 10¹⁶/cm³，1.2×10¹⁷/cm³，2.1×10¹⁷/cm³，4.4×10¹⁷/cm³(ii) a Comparing the carrier concentrations of the four groups of samples in S103, it can be seen that only group a of the four groups of samples meets the standard, and the other electrodesThe deposition condition has larger damage to mercury cadmium telluride, and practice proves that three groups of samples, namely b, c and d, in subsequent IV tests and blind pixel diagrams have poorer performances, so that the growth condition should be eliminated in the process of mercury cadmium telluride metallization.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.