A source measurement unit preamplifier for batch testing of semiconductor devices

Abstract

The invention discloses a source measurement unit preamplifier device for batch testing of semiconductor devices, comprising: an SMU source measurement unit, a matrix switch and a Pre-AMP preamplifier; the Pre-AMP preamplifier is connected to a plurality of DUT devices to be tested and is used to amplify the current of the fA level or pA level obtained by the test and convert it into a current of the nA level or above, and the DUT devices to be tested include pA level and current as low as fA level; the matrix switch is connected to the Pre-AMP preamplifier and is used to control the arbitrary switching of 1 to n+1 DUT devices to be tested; the SMU source measurement unit is connected to the matrix switch and is used to measure the current of the nA level or above by applying different voltages and measuring the current response during semiconductor testing, thereby reducing the requirements for the source meter and the matrix, that is, the current as low as the femtoampere level can be measured by the amplifier.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a source measurement unit preamplifier device for batch testing of semiconductor devices. Background Art

[0002] Source measure units are used to make precise measurements in many areas, including the testing of semiconductor products. Source measure units force a voltage or current and then measure the resulting current or voltage, respectively, and these devices typically measure currents of several picoamperes. Measurements of such low currents are susceptible to adverse effects from unwanted capacitance and other effects, such as dielectric absorption of charge carriers. When performing such measurements in a production environment such as a semiconductor manufacturing plant, where many measurements must be made as quickly as possible, these adverse effects are exacerbated by the use of multiple source measure units, long test cables, and relay switch matrices.

[0003] When performing batch testing in semiconductor factories, multiple devices need to be measured simultaneously, and there are certain requirements for speed. Figure 1 As shown, the biggest problem with this architecture is that if the DUT is a low-current device at the pA level or even the fA level, the test and leakage levels of the SMU and matrix switch must reach the fA level, and such equipment on the market is very expensive. Summary of the invention

[0004] The object of the present invention is to provide a source measurement unit preamplifier device for batch testing of semiconductor devices, which can involve the measurement of very small currents and reduce the requirements for source meters and matrices. That is, through this source measurement unit preamplifier device for batch testing of semiconductor devices, currents as low as femtoampere levels can be measured.

[0005] The present invention provides a source measurement unit preamplifier device for batch testing of semiconductor devices, comprising a SMU source measurement unit, a matrix switch and a Pre-AMP preamplifier;

[0006] The Pre-AMP preamplifier is connected to a plurality of DUT devices to be tested, and is used to amplify the fA level or pA level current obtained by the test, and convert it into nA level and above current. The DUT devices to be tested include pA level and as low as fA level current;

[0007] The matrix switch is connected to the Pre-AMP preamplifier and is used to control any switching of 1 to n+1 DUT devices under test;

[0008] The SMU source measurement unit is connected to the matrix switch and is used to measure nA and above level current by applying different voltages and measuring current response during semiconductor testing;

[0009] In the normal current test mode, the multiple DUT devices under test are connected to the SMU source measurement unit through the matrix switch; in the smaller current test mode, the multiple DUT devices under test are amplified by the Pre-AMP preamplifier and connected to the SMU source measurement unit through the matrix switch; wherein, the smaller current test mode is a current test at pA level and below fA level, and the normal current test mode is a current test above pA level.

[0010] Preferably, the INPUT terminal of the Pre-AMP preamplifier is connected to the Force terminal of the SMU source measurement unit, the SENSE terminal of the Pre-AMP preamplifier is connected to the sense terminal of the SMU source measurement unit, and the OUTPUT terminal of the Pre-AMP preamplifier is connected to the DUT device under test.

[0011] Preferably, the internal circuit of the Pre-AMP preamplifier includes a plurality of switches, a transimpedance amplifier U2, an amplifier U3, an isolated power supply and a plurality of resistors, the INPUT end of the Pre-AMP preamplifier is connected to the output end of the transimpedance amplifier U2 through the resistor R10, the negative input end of the transimpedance amplifier U2 is connected to the OUTPUT end of the Pre-AMP preamplifier, and the positive input end of the transimpedance amplifier U2 is connected to the negative input end of the amplifier U3; and the INPUT end of the Pre-AMP preamplifier is connected to the OUTPUT end of the Pre-AMP preamplifier through the switch K1;

[0012] The INPUT end of the Pre-AMP preamplifier is connected to the switch K2, the resistor R9 and the output end of the amplifier U3, the positive input end of the amplifier U3 and the SENSE end of the Pre-AMP preamplifier are connected from the switch K3 to the OUTPUT end of the Pre-AMP preamplifier, the negative input end of the amplifier U3 is connected to the output end of the amplifier U3, and the SENSE end of the Pre-AMP preamplifier is connected to an isolated power supply.

[0013] Preferably, the negative input terminal of the transimpedance amplifier U2 is respectively connected to a switch and target resistors of different sizes connected to the switch are connected to the output terminal of the transimpedance amplifier U2, so as to perform a preset small current test by switching the resistors.

[0014] Preferably, when performing a preset small current test, the control switch K1 is disconnected, and the control switches K2 and K3 are closed to adapt to current measurements of different magnitudes by switching different resistance gears, and the preset small current is a picoampere level current or a current as low as below the picoampere level to the femtoampere level. Preferably, when performing a preset large current test, the control switch K1 is closed, and the control switch K2 is disconnected, forming a direct setting for the Force terminal of the SMU source measurement unit, and the preset large current is a nanoampere level current and a current above the nanoampere level.

[0015] Preferably, the transimpedance amplifier U2 is used to perform a preset small current test by switching resistors, and convert the test current into a voltage signal through the transimpedance amplifier U2, forming a voltage difference Vtest between the output end of the transimpedance amplifier U2 and the FloatingGnd end.

[0016] Preferably, when the switching resistance is 10G, the measurable current range is below 1pA, when the switching resistance is 100G, the measurable current range is below 100fA, and when the switching resistance is 1TG, the measurable current range is below 10^-8fA.

[0017] Preferably, a controller is also included for controlling the connectivity switching of the Pre-AMP preamplifier.

[0018] Preferably, each of the Pre-AMP preamplifiers is connected to a corresponding DUT device under test, and each of the Pre-AMP preamplifiers is arranged close to each correspondingly connected DUT device under test to reduce the adverse effects of capacitance parasitics and dielectric absorption of charge carriers on circuit performance.

[0019] With respect to the prior art, the present invention has the following beneficial effects:

[0020] The present invention integrates the SMU source measurement unit, matrix switch, Pre-AMP preamplifier and DUT device under test, and the design provides a highly integrated and modular solution. This design simplifies the system architecture, facilitates maintenance and upgrade, and involves the measurement of very small currents, especially the preamplifier used with the source measurement unit. The use of this amplifier can reduce the requirements for the source meter and the matrix, that is, the amplifier can measure currents as low as femtoampere level.

[0021] By switching different target resistances (such as 10G, 100G and 1T), the Pre-AMP preamplifier can perform preset small current tests, covering the current range from picoamperes to femtoamperes. This flexibility enables the device to adapt to current measurement requirements of different magnitudes.

[0022] The present invention uses a transimpedance amplifier U2 to convert the tested current into a voltage signal, thereby allowing more accurate current measurement. This conversion is particularly important for low current testing because it can improve the sensitivity and accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a basic architecture diagram of a source measurement unit preamplifier device for batch testing of semiconductor devices described in the background technology of the present invention;

[0024] Figure 2 It is a principle block diagram of a source measurement unit preamplifier device for batch testing of semiconductor devices in the first embodiment of the present invention;

[0025] Figure 3 1 is an internal circuit diagram of the Pre-AMP preamplifier in the first embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 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 are within the scope of protection of the present invention.

[0027] First embodiment

[0028] When performing batch testing in a semiconductor factory, multiple devices need to be measured simultaneously, and there are certain requirements for speed. The most basic architecture is Figure 1 As shown in , the biggest problem with this architecture is that if the DUT is a low current device at the pA level or even the fA level, the test and leakage levels of the SMU and the matrix switch must reach the fA level, and such equipment on the market is very expensive. The embodiment of the present invention solves the above problem by adding a preamplifier between the matrix switch and the DUT, which is described in detail as follows.

[0029] like Figure 2As shown, the present invention provides a source measurement unit preamplifier device for batch testing of semiconductor devices, comprising: SMU source measurement unit, matrix switch and Pre-AMP preamplifier; Pre-AMP preamplifier, connected to multiple DUT devices under test, used to amplify the fA level or pA level current obtained by the test, and convert it into nA and above level current, wherein the DUT devices under test include pA level and current as low as fA level; matrix switch, connected to the Pre-AMP preamplifier, used to control any switching of 1 to n+1 DUT devices under test; SMU source measurement unit, connected to the matrix switch, used to measure nA and above level current by applying different voltages and measuring current response during semiconductor testing; in normal current test mode, multiple DUT devices under test are connected to the SMU source measurement unit through the matrix switch; in smaller current test mode, multiple DUT devices under test are connected to the SMU source measurement unit through the matrix switch after amplification by the Pre-AMP preamplifier; wherein the smaller current test mode is a current test of pA level and below fA level, and the normal current test mode is a current test of pA level and above. This invention makes full use of the sense capability of the source measurement unit, namely the load line voltage drop compensation mechanism, so that the voltage capability of the previous level source meter remains completely unchanged, and completes the current-to-current conversion, making full use of the large current precision measurement capability of the initial source meter, and achieving the purpose of amplifying and measuring extremely small currents.

[0030] The above scheme introduces the Pre-AMP preamplifier, which can amplify the tiny current of fA level or pA level that is difficult to measure directly to nA level and above, thereby significantly improving the measurement accuracy and sensitivity, which is particularly important for application scenarios such as semiconductor devices that require high-precision current testing. Traditional SMU source measurement units may not be able to directly and accurately measure extremely low levels of current (such as fA or pA level), and the preamplifier device amplifies these tiny currents, allowing the SMU to effectively measure currents in a wider range, thereby expanding its testing capabilities. In semiconductor testing, applying high voltage or high current directly to the device under test may cause damage to the device. Through the use of the Pre-AMP preamplifier, current amplification can be performed without direct contact with the DUT, thereby reducing the potential risk of damage to the DUT. The matrix switch allows multiple DUTs to be connected at the same time, and automatic switching and testing can be achieved through software control, which greatly improves test efficiency and throughput, especially in mass production and automated test environments. The design of the device is highly flexible and scalable, and can be easily adjusted and configured according to different test requirements. For example, it can adapt to different numbers of DUTs by increasing or decreasing the number of channels of the matrix switch, or adapt to different ranges of current tests by replacing Pre-AMP preamplifiers of different specifications. Although the introduction of preamplifiers will increase certain hardware costs, considering its many benefits such as significantly improving test accuracy, expanding test range, protecting DUTs, and improving test efficiency, it may reduce long-term operating costs and improve return on investment as a whole. In this embodiment, the device also includes a controller for controlling the connectivity switching of the Pre-AMP preamplifiers, and all Pre-AMP preamplifiers are connected to the controller, which allows users to easily set and adjust through the controller to achieve automated testing and data processing.

[0031] The INPUT terminal of the Pre-AMP preamplifier is connected to the Force terminal of the SMU source measurement unit, the SENSE terminal of the Pre-AMP preamplifier is connected to the sense terminal of the SMU source measurement unit, and the OUTPUT terminal of the Pre-AMP preamplifier is connected to the DUT device under test. Among them, the SMU source measurement unit and the matrix switch can only test the target level current. The current less than the target level obtained by the SMU source measurement unit and the matrix switch test is amplified by the pre-current amplifier, and the current less than the target level is converted into the target level current to reduce the requirements for the SMU source measurement unit and the matrix switch, so that the current as low as femtoampere level can be measured, and the target level current is nA level current. The embodiment of the present invention relates to the measurement of very small currents, in particular to a preamplifier used with a source measurement unit. The use of this amplifier can reduce the requirements for the source meter and the matrix, that is, the amplifier can measure currents as low as femtoampere level.

[0032] Those skilled in the art can understand that the principle of this embodiment is as follows: if the matrix switch and SMU source measurement unit are selected to test the equipment of the fA and pA level current, it is very expensive. The reason why the above scheme uses the preamplifier to fundamentally solve this problem is that after adding the preamplifier, the SMU source measurement unit and the matrix switch only need to be able to test the nA level current. Because the preamplifier converts the fA and pA level current into the nA level current. That is to say, when testing a pA current, it is actually pA at the preamplifier port, but because it is amplified, the current is amplified to nA. At this time, the SMU source measurement unit and the matrix switch can detect the nA level current, and then the system determines that the preamplifier is working at this time, then automatically divide the nA level current by the amplification factor such as 1000, assuming that the amplification factor is 1000, which is the pA level. At this time, the system measures the pA current. In this way, it is enough for the SMU source measurement unit and the matrix switch to test nA, and smaller currents can be amplified by the preamplifier, so the requirements for the SMU and the matrix are reduced.

[0033] In one embodiment, each of the Pre-AMP preamplifiers is connected to a corresponding DUT device under test, and each of the Pre-AMP preamplifiers is arranged close to each corresponding DUT device under test to reduce the adverse effects of capacitance parasitics and dielectric absorption of charge carriers on circuit performance. It can be understood that each amplifier can correspond to a DUT, and the amplifier is very close to the device under test, which minimizes the problems caused by capacitance parasitics and dielectric absorption of charge carriers. This layout optimization helps to improve the overall measurement performance and reliability. Figure 3As shown, the internal circuit of the Pre-AMP preamplifier includes a plurality of switches, a transimpedance amplifier U2, an amplifier U3, an isolated power supply and a plurality of resistors. The INPUT end of the Pre-AMP preamplifier is connected to the output end of the transimpedance amplifier U2 through a resistor R10, the negative input end of the transimpedance amplifier U2 is connected to the OUTPUT end of the Pre-AMP preamplifier, and the positive input end of the transimpedance amplifier U2 is connected to the negative input end of the amplifier U3; and the INPUT end of the Pre-AMP preamplifier is connected to the switch. The switch K1 is connected to the OUTPUT end of the Pre-AMP preamplifier; the INPUT end of the Pre-AMP preamplifier is connected to the switch K2, the resistor R9 and the output end of the amplifier U3, the positive input end of the amplifier U3 is connected to the SENSE end of the Pre-AMP preamplifier, the switch K3 is connected to the OUTPUT end of the Pre-AMP preamplifier, the negative input end of the amplifier U3 is connected to the output end of the amplifier U3, and the SENSE end of the Pre-AMP preamplifier is connected to the isolated power supply. The negative input end of the transimpedance amplifier U2 is respectively connected to the switch and the target resistors of different sizes connected to the switch to the output end of the transimpedance amplifier U2, so as to perform a preset small current test by switching the resistor, such as the target resistance is 10G, 100G and 1T. The above signal path connection method ensures stable transmission of the signal and minimized interference.

[0034] This embodiment describes a circuit configuration for measuring extremely small currents through the above scheme, and realizes high-sensitivity current-to-voltage conversion through the combination of a transimpedance amplifier and a precision resistor. The detailed working process and principle are described as follows:

[0035] 1. Circuit connection method: INPUT is connected to the Force terminal of SMU, SENSE is connected to the sense port of SMU, and OUTPUT is connected to DUT, which ensures that during the test, the output voltage of SMU can accurately control and measure the current passing through DUT.

[0036] 2. Extremely small current test configuration: When performing a preset small current test, the control switch K1 is disconnected, and the control switches K2 and K3 are closed to adapt to current measurements of different magnitudes by switching different resistance gears. The preset small current is a picoampere level current or a current as low as below the picoampere level to the femtoampere level. Extremely small current usually refers to a very small current, which is much lower than the current level commonly seen in daily life. In the semiconductor field, extremely small currents can also be nanoamperes (nA, 10^-9A), picoamperes (pA, 10^-12A) or even femtoamperes (fA, 10^-15A) or smaller current levels. It can be understood that when performing an extremely small current test, K1 is disconnected, and K2 and K3 are closed. In this configuration, the transimpedance amplifier U2 adapts to current measurements of different magnitudes by switching different resistance gears. For example, a 10GΩ resistor can measure currents below 1pA, and a 100GΩ resistor can measure currents below 100fA. The transimpedance amplifier converts the test current into a voltage signal, and forms a voltage difference Vtest between the output end of U2 and the FloatingGnd end. Specifically, the transimpedance amplifier U2 is used to perform a preset small current test by switching the resistor, and converts the test current into a voltage signal through the transimpedance amplifier U2, and forms a voltage difference Vtest between the output end of the transimpedance amplifier U2 and the FloatingGnd end. Among them, when the switching resistor is 10G, the current range that can be measured is a current below 1pA, when the switching resistor is 100G, the current range that can be measured is a current below 100fA, and when the switching resistor is 1TG, the current range that can be measured is a current below 10fA.

[0037] 3. Voltage feedback mechanism: Due to the characteristics of SMU, the voltage at the Sense terminal is the actual voltage to be output. In order to keep the Output voltage equal to the Sense terminal voltage, the Input voltage needs to be adjusted to be equal to Vtest. In this way, by monitoring the current at the Input terminal, that is, the current flowing through R9, the current test current can be known.

[0038] 4. High current test configuration: When performing a preset high current test, the control switch K1 is closed and the control switch K2 is opened, forming a direct setting for the Force end of the SMU source measurement unit. The preset high current is a current at the nanoampere nA level and above. For semiconductor testing, nanoampere nA level and above is called a high current. At this time, a larger current can be measured directly without the need for conversion through a transimpedance amplifier. The switch state of K3 is determined by the specific test requirements, but has no effect in this circuit test.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A source measurement unit preamplifier for batch testing of semiconductor devices, characterized in that: include: SMU source measurement unit, matrix switch and Pre-AMP preamplifier, The Pre-AMP preamplifier is connected to a plurality of DUT devices to be tested, and is used to amplify the fA level or pA level current obtained by the test, and convert it into a level current above nA. The DUT devices to be tested include pA level and as low as fA level current; The matrix switch is connected to the Pre-AMP preamplifier and is used to control any switching of 1 to n+1 DUT devices under test; The SMU source measurement unit is connected to the matrix switch and is used to measure currents above nA by applying different voltages and measuring current responses during semiconductor testing; In a normal current test mode, a plurality of the DUT devices under test are connected to the SMU source measurement unit through the matrix switch; In the smaller current test mode, the multiple DUT devices under test are amplified by the Pre-AMP preamplifier and then connected to the SMU source measurement unit through the matrix switch; wherein the smaller current test mode is a current test below the pA level and the fA level, and the normal current test mode is a current test above the pA level; The internal circuit of the Pre-AMP preamplifier includes a plurality of switches, a transimpedance amplifier U2, an amplifier U3, an isolated power supply and a plurality of resistors. The INPUT end of the Pre-AMP preamplifier is connected to the output end of the transimpedance amplifier U2 through a resistor R10, the negative input end of the transimpedance amplifier U2 is connected to the OUTPUT end of the Pre-AMP preamplifier, and the positive input end of the transimpedance amplifier U2 is connected to the negative input end of the amplifier U3; and the INPUT end of the Pre-AMP preamplifier is connected to the OUTPUT end of the Pre-AMP preamplifier through a switch K1; The INPUT end of the Pre-AMP preamplifier is connected to the switch K2, the resistor R9 and the output end of the amplifier U3, the positive input end of the amplifier U3 and the SENSE end of the Pre-AMP preamplifier are connected from the switch K3 to the OUTPUT end of the Pre-AMP preamplifier, the negative input end of the amplifier U3 is connected to the output end of the amplifier U3, and the SENSE end of the Pre-AMP preamplifier is connected to an isolated power supply.

2. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 1, characterized in that: The INPUT terminal of the Pre-AMP preamplifier is connected to the Force terminal of the SMU source measurement unit, the SENSE terminal of the Pre-AMP preamplifier is connected to the sense terminal of the SMU source measurement unit, and the OUTPUT terminal of the Pre-AMP preamplifier is connected to the DUT device under test.

3. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 1, characterized in that: The negative input terminal of the transimpedance amplifier U2 is respectively connected to the switch and the target resistors of different sizes connected to the switch to the output terminal of the transimpedance amplifier U2, so as to perform a preset small current test by switching the resistors.

4. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 1, characterized in that: When performing a preset small current test, the control switch K1 is opened, and the control switches K2 and K3 are closed to adapt to current measurements of different magnitudes by switching different resistance gears. The preset small current is a current below the picoampere level to the femtoampere level.

5. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 1, characterized in that: When performing a preset high current test, the control switch K1 is closed and the control switch K2 is opened, forming a through setting for the Force terminal of the SMU source measurement unit. The preset high current is a current above nA level.

6. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 1, characterized in that: The transimpedance amplifier U2 is used to perform a preset small current test by switching resistors, and convert the tested current into a voltage signal through the transimpedance amplifier U2, forming a voltage difference Vtest between the output end of the transimpedance amplifier U2 and the FloatingGnd end.

7. The source measurement unit preamplifier for batch testing of semiconductor devices according to claim 4, characterized in that: When the switching resistance is 10G, the current range that can be measured is below 1pA. When the switching resistance is 100G, the current range that can be measured is below 100fA. When the switching resistance is 1TG, the current range that can be measured is below 10 -8 Current below fA.

8. The source measurement unit preamplifier for semiconductor device batch testing according to claim 1, characterized in that: A controller is also included for controlling the connection switching of the Pre-AMP preamplifier.

9. The source measurement unit preamplifier for semiconductor device batch testing according to claim 1, characterized in that: Each of the Pre-AMP preamplifiers is connected to a corresponding DUT device under test, and each of the Pre-AMP preamplifiers is arranged close to each correspondingly connected DUT device under test to reduce the adverse effects of capacitance parasitics and dielectric absorption of charge carriers on circuit performance.

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