Power device and current gain test method thereof

Abstract

The invention discloses a power device and a current gain test method thereof. The current gain test method of the power device comprises the following steps: providing a to-be-tested power device; the to-be-tested power device comprises a base electrode, a collector electrode and an emitter electrode; electrically connecting the to-be-tested power device to the current gain test equipment; variable voltage is applied between the base electrode and the emitter electrode, and fixed voltage is applied between the collector electrode and the emitter electrode, so that a current gain test is carried out on the power device; wherein the fixed voltage is greater than the peak voltage of the variable voltage. According to the technical scheme of the embodiment of the invention, electrons can be prevented from being crowded in the base region, so that the power device always keeps high current gain, the current gain is kept stable, and the working stability of the power device is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a power device and a current gain testing method thereof. Background Art

[0002] Common emitter heterojunction bipolar transistor (HBT) has the advantages of high current gain, high cut-off frequency, high output resistance and good noise characteristics due to its heterojunction structure.

[0003] The existing common emitter HBT current gain test method (Gummel test method) is to apply a forward voltage between the base and the emitter, and the voltage applied between the collector and the emitter is consistent with the voltage applied between the base and the emitter. However, this will cause current crowding in the carrier transport between the emitter and the base, and the common emitter HBT will heat up severely, causing a rapid decrease in current gain, and the stability of the common emitter HBT is poor. Summary of the invention

[0004] The present invention provides a power device and a current gain testing method thereof, so as to solve the problem that the current gain of the power device cannot be kept stable under high voltage.

[0005] According to one aspect of the present invention, a current gain testing method for a power device is provided, comprising:

[0006] A power device to be tested is provided; the power device to be tested comprises a base, a collector and an emitter;

[0007] Electrically connecting the power device to be tested to a current gain testing device;

[0008] Applying a variable voltage between the base and the emitter, and applying a fixed voltage between the collector and the emitter, so as to perform a current gain test on the power device;

[0009] Wherein, the fixed voltage is greater than the peak voltage of the variable voltage.

[0010] Optionally, the variable voltage ranges from 0 to 1.5V, and the fixed voltage ranges from 3V.

[0011] Optionally, the power device to be tested includes:

[0012] substrate;

[0013] A collector region located on the surface of the substrate;

[0014] A base region located at a side of the collector region away from the substrate;

[0015] An emitter region located at a side of the base region away from the collector region;

[0016] The collector region and the emitter region are both doped with n-type doping, and the base region is doped with p-type doping.

[0017] Optionally, the collector region includes at least two stacked sub-collector regions with gradient doping concentrations;

[0018] Along the direction from close to the substrate to far away from the substrate, the doping concentration of each sub-collector region gradually decreases.

[0019] Optionally, along a direction from close to the substrate to far away from the substrate, the thickness of each sub-collector region gradually decreases.

[0020] Optionally, along a direction from close to the substrate to far away from the substrate, a variation trend of the doping concentration of the base region increases linearly.

[0021] Optionally, the doping concentration of each sub-collector region is 1×10 16 ~1×10 17 cm -3 within the range.

[0022] Optionally, the doping concentration of the base region is 1×10 19 ~1×10 20 cm -3 within the range.

[0023] Optionally, the current gain testing method of the power device further includes:

[0024] Current gain test data is collected, and a gain curve is drawn according to the current gain test data.

[0025] According to another aspect of the present invention, there is provided a power device used as a power amplifier, and a current gain test is performed using the current gain test method for a power device as described in any embodiment of the first aspect.

[0026] The current gain test method of the power device provided by the embodiment of the present invention is to electrically connect the base, collector and emitter of the power device to be tested to the corresponding interface of the current gain test equipment, and apply a variable voltage between the base and the emitter, and apply a fixed voltage between the collector and the emitter, and make the fixed voltage always greater than the peak voltage of the variable voltage, so as to perform a current gain test on the power device to be tested. By adopting such a current gain test method, the base region and the collector region can always be in a reverse bias state, strengthen the built-in electric field range between the base region and the collector region, accelerate the movement of electrons from the emitter region to the collector region, thereby avoiding the crowding of electrons in the base region, which is beneficial to improving the heating phenomenon of the power device, so that the power device always maintains a high current gain, and the current gain remains stable, which is beneficial to improving the stability of the power device during operation.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a schematic flow chart of a current gain testing method of a power device provided in accordance with an embodiment of the present invention;

[0030] Figure 2 is an equivalent circuit diagram of a current gain method of a power device provided according to an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of a cross-sectional structure of a power device to be tested provided according to an embodiment of the present invention;

[0032] Figure 4 is a flow chart of another current gain testing method for a power device provided according to an embodiment of the present invention;

[0033] Figure 5 is a schematic diagram of a current gain test curve provided according to an embodiment of the present invention;

[0034] Figure 6 It is a schematic diagram of the gain curve obtained by processing the current gain test curve;

[0035] Figure 7It is a schematic diagram of electric potential change provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] As described in the background technology, the existing Gummel test method of the common emitter HBT is to apply a forward voltage between the base and the emitter, and the voltage applied between the collector and the emitter is consistent with the voltage applied between the base and the emitter, that is, the base potential is higher than the emitter potential, and the base and the collector are of equal potential. In the common emitter HBT, the carriers from the emitter will be accelerated to move to the collector region under the action of the built-in electric field between the base and the collector when passing through the base and the collector. However, when the voltage between the emitter and the base reaches a certain level, the built-in electric field between the base and the collector cannot allow the carriers to move quickly to the collector region, causing current congestion in the carrier transport between the emitter and the base, severe heat generation, and an increase in hole transport from the base to the emitter, thereby causing the current gain of the common emitter HBT to drop rapidly.

[0039] Based on the above technical problems, the embodiments of the present invention propose the following technical solutions:

[0040] An embodiment of the present invention provides a current gain testing method for a power device. Figure 1 The present invention provides a flow chart of a method for testing the current gain of a power device. Figure 1 As shown, the current gain test method of the power device specifically includes the following steps:

[0041] S110, providing a power device to be tested; the power device to be tested includes a base, a collector and an emitter.

[0042] Specifically, a representative sample with good appearance and no obvious defects is selected as the power device to be tested, and the power device to be tested is cleaned. For example, a dust-free cloth dipped in an appropriate amount of organic solvent can be used to gently wipe the surface of the sample to remove dust, oil and other impurities on the surface, thereby ensuring the accuracy of subsequent tests.

[0043] S120, electrically connecting the power device to be tested to a current gain test device.

[0044] Specifically, a semiconductor parameter analyzer can be used as a current gain test device, and the base, collector and emitter of the power device to be tested are electrically connected to the corresponding interfaces of the current gain test device respectively, and good contact between the electrodes is ensured to prevent large contact resistance from affecting the test results.

[0045] S130, applying a variable voltage between the base and the emitter, and applying a fixed voltage between the collector and the emitter, so as to perform a current gain test on the power device; wherein the fixed voltage is greater than the peak voltage of the variable voltage.

[0046] Specifically, before the test starts, relevant test parameters are set for the test equipment, for example, the test parameters may include parameters such as the voltage scanning range, scanning step length, and temperature of the base and emitter, which are not limited here. In an embodiment of the present invention, a variable voltage is applied between the base and the emitter, and a fixed voltage is applied between the collector and the emitter, and the fixed voltage is always greater than the peak voltage of the variable voltage, and the base and emitter of the power device to be tested are scanned and tested within the voltage scanning range of the variable voltage. In this way, the base region and the collector region are always in a reverse bias state, which is equivalent to adding an additional reverse electron acceleration electric field, which is conducive to allowing electrons from the emitter region to pass through the base region to the collector region more quickly, avoiding crowding of electrons in the base region, and improving the heating phenomenon of the power device, so that the power device can always maintain a high current gain and a stable current gain.

[0047] The current gain test method of the power device provided by the embodiment of the present invention is to electrically connect the base, collector and emitter of the power device to be tested to the corresponding interface of the current gain test equipment, and apply a variable voltage between the base and the emitter, and apply a fixed voltage between the collector and the emitter, and make the fixed voltage always greater than the peak voltage of the variable voltage, so as to perform a current gain test on the power device to be tested. By adopting such a current gain test method, the base region and the collector region can always be in a reverse bias state, strengthen the built-in electric field range between the base region and the collector region, accelerate the movement of electrons from the emitter region to the collector region, thereby avoiding the crowding of electrons in the base region, which is beneficial to improving the heating phenomenon of the power device, so that the power device always maintains a high current gain, and the current gain remains stable, which is beneficial to improving the stability of the power device during operation.

[0048] Optionally, Figure 2 is an equivalent circuit diagram of a current gain method of a power device provided by an embodiment of the present invention. Based on the above embodiment, see Figure 2 The variable voltage range includes 0~1.5V, and the fixed voltage includes 3V.

[0049] Specifically, the voltage between the base region 30 and the emitter region 40 can be determined by V be It means that the variable voltage applied between the base region 30 and the emitter region 40 can be changed in the range of 0 to 1.5 V, and the potential of the base region 30 is higher than the potential of the emitter region 40, that is, V be =0~1.5V. The voltage between the collector region 20 and the emitter region 40 can be determined by V ce Indicates that the potential of the collector region 20 is higher than the potential of the emitter region 40. Since the peak voltage of the variable voltage between the base region 30 and the emitter region 40 is 1.5V, a fixed voltage greater than 1.5V can be applied between the collector region 20 and the emitter region 40. Exemplarily, the fixed voltage can be 3V, which is not limited here. Such application of voltage can make the potential of the collector region 20 always higher than the potential of the base region 30, that is, the base region 30 and the collector region 20 are always in a reverse biased state, which is beneficial to strengthen the built-in electric field of the base region 30 and the collector region 20, thereby accelerating the electrons from the emitter region 40 to move to the collector region 20, so that the current of the power device always maintains a high gain.

[0050] Optionally, Figure 3 FIG. 1 is a schematic diagram of a cross-sectional structure of a power device to be tested provided by an embodiment of the present invention. Figure 3As shown, the power device to be tested includes: a substrate 10, a collector region 20, a base region 30 and an emitter region 40. The collector region 20 is located on the surface of the substrate 10, the base region 30 is located on the side of the collector region 20 away from the substrate 10, and the emitter region 40 is located on the side of the base region 30 away from the collector region 20; wherein the doping types of the collector region 20 and the emitter region 40 are both n-type, and the doping type of the base region 30 is p-type.

[0051] Specifically, the substrate 10 may be made of GaAs material. The collector region 20 arranged on the surface of the substrate 10 may be made of GaAs material doped with silicon, that is, forming an n-type doped collector region 20. The base region 30 arranged on the side of the collector region 20 away from the substrate 10 may be made of GaAs material doped with carbon, that is, forming a p-type doped base region 30. The emitter region 40 arranged on the side of the base region 30 away from the collector region 20 may be made of GaAs material doped with silicon, that is, forming an n-type doped emitter region 40. It should be noted that the power device to be tested may use GaAs material as the substrate material, or other materials may be selected as the substrate material, such as InP, etc., which are not limited here.

[0052] Optionally, based on the above embodiments, continue to refer to Figure 3 The collector region 20 includes at least two stacked sub-collector regions 21 with gradient doping concentrations; the doping concentration of each sub-collector region 21 gradually decreases from close to the substrate 10 to far away from the substrate 10. The thickness of each sub-collector region 21 gradually decreases from close to the substrate 10 to far away from the substrate 10. The doping concentration of the base region 30 increases linearly from close to the substrate 10 to far away from the substrate 10.

[0053] Specifically, since the film thickness of the collector region 20 is relatively thick, the variation trend of the silicon doping concentration in the collector region 20 can be set to a gradient variation trend, that is, the collector region 20 may include at least two layers of sub-collector regions 21, and from the direction close to the substrate 10 to the direction away from the substrate 10, the concentration of doped silicon in each sub-collector region 21 presents a gradient decreasing variation trend. Exemplarily, in an embodiment of the present invention, Figure 3 The collector region 20 of the power device to be tested includes four layers of sub-collector regions 21, and the silicon doping concentrations of the sub-collector regions 21 are respectively N3, N2, N1, and N0 from the direction close to the substrate 10 to the direction away from the substrate 10. The doping concentrations of the four layers of sub-collector regions 21 have a gradient decreasing trend of N3>N2>N1>N0. For example, the doping concentrations of the sub-collector regions 21 are all between 1×10 16 ~1×10 17 cm -3According to the silicon doping concentration of each sub-collector region 21, each sub-collector region 21 can be set to have a corresponding different thickness, and each sub-collector region 21 has a certain thickness variation trend, that is, from the direction close to the substrate 10 to the direction away from the substrate 10, the thickness of each sub-collector region 21 shows a gradually decreasing variation trend.

[0054] For the base region 30, since the film thickness of the base region 30 is relatively thin, the variation trend of the carbon doping concentration in the base region 30 can be set to a gradual variation trend. For example, in an embodiment of the present invention, Figure 3 The carbon doping concentration of the base region 30 of the power device to be tested changes from P- to P+ in a linear gradient from low to high, from close to the substrate 10 to far away from the substrate 10. For example, the doping concentration of the base region is 1×10 19 ~1×10 20 cm -3 The silicon doping concentration of the emitter region 40 may be denoted as N.

[0055] In the embodiment of the present invention, such a power device to be tested is prepared, and an accelerating electric field for electrons can be established, so that the electrons from the emitter region 40 can quickly move to the collector region 20 through the base region 30. In addition, a forward bias is applied to the base region 30 and the emitter region 40, and the electrons in the emitter region 40 move toward the base region 30. The voltages of the collector region 20 and the emitter region 40 are always greater than the peak voltage of the variable voltage applied to the base region 30 and the emitter region 40, which is equivalent to adding an additional electron accelerating electric field, so that the electrons from the emitter region 40 can move to the collector region 20 through the base region 30 more quickly, avoiding crowding of electrons in the base region 30, improving the heating phenomenon of the power device to be tested, and maintaining a high current gain of the power device to be tested and improving the stability of the power device to be tested during operation.

[0056] Optionally, Figure 4 FIG. 1 is a flow chart of another current gain test method for a power device provided by an embodiment of the present invention. Figure 4 As shown, the current gain test method of the power device specifically includes the following steps:

[0057] S210, providing a power device to be tested; the power device to be tested includes a base, a collector and an emitter.

[0058] S220, electrically connecting the power device to be tested to a current gain test device.

[0059] S230, applying a variable voltage between the base and the emitter, and applying a fixed voltage between the collector and the emitter, so as to perform a current gain test on the power device; wherein the fixed voltage is greater than the peak voltage of the variable voltage.

[0060] S240, collecting current gain test data, and drawing a gain curve according to the current gain test data.

[0061] Specifically, during the test, a variable voltage is applied between the base and the emitter to scan with a certain scanning step length, and the changes of the base current and the collector current are tested during the scanning process, and the relationship curve between the base current and the variable voltage and the relationship curve between the collector current and the variable voltage are obtained, that is, the current gain test data is obtained. A gain curve can be drawn based on the current gain test data, so that the current gain of the power device to be tested can be intuitively seen as the voltage between the base and the emitter changes. Figure 5 is a schematic diagram of a current gain test curve provided by an embodiment of the present invention, Figure 6 It is a schematic diagram of the gain curve obtained by processing the current gain test curve. Figure 7 Schematic diagram of potential change provided by an embodiment of the present invention. Figure 5 The horizontal axis of the curve represents the voltage between the base and the emitter, in volts; the vertical axis of the curve represents the base current and the collector current, in amperes. The base current can be expressed by I b Indicates that the collector current can be expressed by I c express. Figure 5 , the current gain test curves before and after the structure of the power device to be tested and the applied voltage are improved are shown in FIG. Figure 5 The black curve 01 in the figure represents the base current gain test curve before improvement, and the red curve 02 represents the base current gain test curve after improvement; the black curve 03 represents the collector current gain test curve before improvement, and the red curve 04 represents the collector current gain test curve after improvement. Figure 6 The horizontal axis of the curve represents the voltage between the base and the emitter, in volts; the vertical axis of the curve represents the current gain, which is expressed by I c / I b express. Figure 6 The current gain variation curve after the voltage between the base and the emitter is greater than 1.1V is shown. Figure 6 The black curve 05 in the figure represents the gain curve before improvement. Figure 6 The red curve 06 in the figure shows the improved gain curve. Figure 5 and Figure 6 It can be seen that before the current gain test of the power device to be tested is improved, the base current I b At larger V be The collector current I c Maintain a smooth change, resulting in a current gain I c / I b There is a sharp drop in the base current Ib At larger V be The reason for the sharp increase under bias may be that when a large voltage is applied externally to generate a large current, heat accumulation occurs inside the power device to be tested, making the activity of holes moving from the base region to the emitter region higher. A fixed voltage greater than the voltage between the base and the emitter is applied between the collector and the emitter, and a power device to be tested with a corresponding change trend in doping concentration is prepared, see Figure 7 , where region 07 represents the emitter region of the power device to be tested, region 08 represents the base region with a linear gradient of doping concentration, and region 09 represents the collector region with a gradient of doping concentration; the solid line 010 represents the potential curve where the doping concentrations of the base region and the collector region in the power device to be tested do not have a corresponding change, and the dotted line 011 represents the potential curve where the doping concentrations of the base region and the collector region in the power device to be tested do have a corresponding change. Figure 7 It can be seen that the base region and collector region with corresponding changes in doping concentration establish an electron accelerating electric field inside the power device to be tested, which can make the base current be It remains stable under bias, and the collector current I c Keep the change smoothly, so that the current gain I c / I b It can remain stable even at high voltage, which is beneficial to improve the stability of the power device under test during operation.

[0062] The embodiment of the present invention also provides a power device. The power device can be used in the radio frequency front end in the field of wireless communication and used as a power amplifier. By using the current gain test method provided in any of the above embodiments to apply corresponding voltages between the base region and the emitter region and between the collector region and the emitter region, an accelerating electric field for electrons can be effectively established inside the power device to be tested, ensuring stable and rapid transport of electrons from the emitter region to the collector region, and being unaffected by the external environment, it is beneficial to improve the stability of the power device to be tested during operation.

[0063] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A current gain test method for a power device, characterized in that: include: A power device to be tested is provided; the power device to be tested comprises a base, a collector and an emitter; Electrically connecting the power device to be tested to a current gain test device; Applying a variable voltage between the base and the emitter, and applying a fixed voltage between the collector and the emitter, so as to perform a current gain test on the power device; Wherein, the fixed voltage is greater than the peak voltage of the variable voltage.

2. The current gain test method of a power device according to claim 1, characterized in that: The variable voltage ranges from 0 to 1.5V, and the fixed voltage ranges from 3V.

3. The current gain test method of a power device according to claim 1, characterized in that: The power device to be tested comprises: substrate; A collector region located on the surface of the substrate; A base region located at a side of the collector region away from the substrate; An emitter region located at a side of the base region away from the collector region; The collector region and the emitter region are both doped with n-type doping, and the base region is doped with p-type doping.

4. The current gain test method of a power device according to claim 3, characterized in that: The collector region includes at least two stacked sub-collector regions with gradient doping concentrations; Along the direction from close to the substrate to far away from the substrate, the doping concentration of each sub-collector region gradually decreases.

5. The current gain test method of a power device according to claim 4, characterized in that: Along the direction from close to the substrate to far away from the substrate, the thickness of each sub-collector region gradually decreases.

6. The current gain test method of a power device according to claim 3, characterized in that: Along the direction from close to the substrate to far away from the substrate, the variation trend of the doping concentration of the base region increases linearly.

7. The current gain test method of a power device according to claim 4, characterized in that: The doping concentration of each sub-collector region is 1×10 16 ~1×10 17 cm -3 within the range.

8. The current gain test method of a power device according to claim 6, characterized in that: The doping concentration of the base region is 1×10 19 ~1×10 20 cm -3 within the range.

9. The current gain test method of a power device according to claim 1, characterized in that: Also includes: Current gain test data is collected, and a gain curve is drawn according to the current gain test data.

10. A power device, characterized in that: Used as a power amplifier, the current gain test is performed using the current gain test method for a power device as described in any one of claims 1 to 9.

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