Constant current power supply and semiconductor measuring device

Abstract

The invention provides a constant current power supply and a semiconductor measuring device. The constant current power supply comprises a current suction module. The current suction module comprises a first operational amplifier, a second operational amplifier and a field effect transistor. The first input end of the first operational amplifier is connected with a first direct-current voltage provided externally, the second input end of the first operational amplifier is connected with the output end of the second operational amplifier, and the output end of the first operational amplifier is connected with the grid electrode of the field effect transistor. The first input end of the second operational amplifier is connected with the drain electrode of the field effect transistor and is grounded through a load resistor, and the second input end of the second operational amplifier is connected with constant voltage. The source electrode of the field effect transistor is connected with an external second direct current voltage and is used for generating an output current with a corresponding amplitude according to an output voltage provided by the output end of the first operational amplifier and providing a first feedback voltage for the first input end of the second operational amplifier through the load resistor; and then a second feedback voltage is provided for the second input end of the first operational amplifier so as to adjust and stabilize the amplitude of the output current.

Description

Technical Field

[0001] The present invention relates to semiconductor measurement technology, and in particular to a constant current power supply and a semiconductor measurement device. Background Art

[0002] With the continuous emergence of new thin film materials, nano-thin film technology has been widely used. Rapid, low-cost, non-destructive and accurate measurement of the thickness of nano-thin film materials is of great significance to the development of nano-technology.

[0003] Ellipsometry is an optical metrology technology that uses polarized light to characterize film thickness and optical constants. It has the advantages of fast measurement speed, high accuracy and non-contact non-destructive measurement. In recent years, it has been widely used in the field of nano-measurement and has gradually become the mainstream trend of future development. In the design of power supply excitation circuits for ellipsometry, high-precision constant current sources are widely used due to their advantages such as wide spectrum response range, fast response speed, high constant current accuracy, long-term stable operation, and suitability for various types of loads. However, existing light sources generally have the problem that the output light intensity is easily weakened with working time, and the light intensity jitter is easily generated due to fluctuations in the driving current, thereby affecting the stability of semiconductor measurement results.

[0004] In order to overcome the above-mentioned defects of the prior art, the art is in urgent need of a light source driving technology for adjusting and stabilizing the amplitude of the driving current to stabilize the output light intensity of the light source module, thereby improving the stability of semiconductor measurement results. Summary of the invention

[0005] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or decisive elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a constant current power supply and a semiconductor measurement device, which can adjust and stabilize the amplitude of the output current by setting a current self-locking current absorption module to stabilize the output light intensity of the light source module, thereby improving the stability of the semiconductor measurement results.

[0007] Specifically, the above-mentioned constant current power supply provided according to the first aspect of the present invention includes a current absorption module. The current absorption module includes a first operational amplifier, a second operational amplifier and a field effect transistor. The first input terminal of the first operational amplifier is connected to a first DC voltage provided externally, the second input terminal thereof is connected to the output terminal of the second operational amplifier, and the output terminal thereof is connected to the gate of the field effect transistor. The first input terminal of the second operational amplifier is connected to the drain of the field effect transistor and is grounded via a load resistor, while the second input terminal thereof is connected to a constant voltage. The source of the field effect transistor is connected to an external second DC voltage, and is used to generate an output current of a corresponding amplitude at its drain according to the output voltage provided at the output terminal of the first operational amplifier, and to provide a first feedback voltage to the first input terminal of the second operational amplifier via the load resistor, and then to provide a second feedback voltage to the second input terminal of the first operational amplifier via the output terminal of the second operational amplifier, so as to adjust and stabilize the amplitude of the output current.

[0008] Further, in some embodiments of the present invention, the field effect transistor operates in its linear region. The output current is proportional to the output voltage provided by the output terminal of the first operational amplifier. The first feedback voltage is proportional to the output current. The second feedback voltage is proportional to the difference between the first feedback voltage and the constant voltage. The output voltage provided by the output terminal of the first operational amplifier is proportional to the difference between the first DC voltage and the second feedback voltage.

[0009] Furthermore, in some embodiments of the present invention, the constant current power supply further includes a power supply module, configured to provide the first DC voltage and / or the second DC voltage to the current sink module.

[0010] Furthermore, in some embodiments of the present invention, the constant current power supply further comprises a main controller module. The main controller module is connected to the power module and is used to provide a first control instruction indicating a target current amplitude to the power module, so as to provide a first DC voltage of a corresponding amplitude to the first input terminal of the first operational amplifier via the power module.

[0011] Furthermore, in some embodiments of the present invention, the constant current power supply further comprises a current detection module. The current detection module is connected to the main controller module and grounded via the load resistor, and is used to collect the first feedback voltage to determine the amplitude of the output current, and transmit the amplitude of the output current to the main controller module for negative feedback control of the current absorption module.

[0012] Furthermore, in some embodiments of the present invention, the main controller module is also configured to: before providing the first control instruction to the power supply module, provide the power supply module with a second control instruction indicating a plurality of first DC voltages in advance, and obtain the corresponding output current amplitudes respectively through the current detection module; determine a first correspondence between the first DC voltage and the output current according to the first DC voltage and the output current corresponding to each of the second control instructions; and generate and provide a corresponding first control instruction to the power supply module according to the target current amplitude and the first correspondence.

[0013] Furthermore, in some embodiments of the present invention, the current detection module also obtains the amplitude of the output current at multiple moments in response to the second control instruction issued by the main controller module. The main controller module is also configured to: determine the current stabilization time corresponding to each target current amplitude according to the change gradient of the amplitude of the output current at multiple moments; and after providing the first control instruction to the power supply module, control the current detection module to collect the amplitude of the output current according to the current stabilization time corresponding to the target current amplitude.

[0014] Furthermore, in some embodiments of the present invention, the constant current power supply further includes a data transmission module. The data transmission module is connected to the main controller module and an external host computer, and is used to transmit a third control instruction indicating the target current amplitude provided by the host computer to the main controller module, and transmit the output current amplitude data collected by the current detection module from the main controller module to the host computer.

[0015] Further, in some embodiments of the present invention, the current detection module and the main controller module use a SPI data transmission method based on a serial peripheral interface. And / or the main controller module and the data transmission module use a TTL signal-based data transmission method. And / or the data transmission module and the host computer use a USB signal-based data transmission method.

[0016] Furthermore, in some embodiments of the present invention, the constant current power supply includes a plurality of current sink modules. The current detection module uses an AD7794 chip, which has a plurality of differential sampling channels, for synchronously sampling the first feedback voltages of the plurality of current sink modules, and synchronously transmitting the corresponding output current amplitudes to the main controller module, so that the main controller module can synchronously perform negative feedback control on each current sink module.

[0017] Further, in some embodiments of the present invention, the first operational amplifier and / or the second operational amplifier are AD8610 operational amplifiers, and / or the field effect transistors are MOSFET IRF640 metal oxide semiconductor field effect transistors, and / or the main controller module is an STM32 single chip microcomputer.

[0018] In addition, the semiconductor measurement device provided according to the second aspect of the present invention includes the constant current power supply, the first light source module, and the ellipsometric measurement module provided by the first aspect of the present invention. The constant current power supply is at least used to provide a constant first output current for the first light source module of the semiconductor measurement device. The first light source module is used to output a first illumination light corresponding to the light intensity according to the first output current provided by the first current absorption module of the constant current power supply. The ellipsometric measurement module is used to provide a third control instruction corresponding to the first target light intensity to the constant current power supply, polarize the first illumination light output by the first light source module, and irradiate the obtained polarized light onto the surface of the sample to be measured, so as to determine the film thickness on the surface of the sample to be measured according to the first reflected light signal of the surface of the sample to be measured.

[0019] Furthermore, in some embodiments of the present invention, the ellipsometric measurement module is connected to the data transmission module of the constant current power supply and is configured as follows: before providing the third control instruction to the constant current power supply, providing a fourth control instruction indicating a plurality of first DC voltages to a main controller module of the constant current power supply via the data transmission module in advance, and respectively collecting the intensity amplitudes of the reflected light on the surface of the sample to be measured; determining a second correspondence between the first DC voltage and the light intensity amplitude according to the first DC voltage and the light intensity amplitude corresponding to each of the fourth control instructions; and generating and providing a corresponding third control instruction to the constant current power supply according to the target light intensity and the second correspondence.

[0020] Furthermore, in some embodiments of the present invention, the ellipsometric measurement module is also configured to: obtain, via the data transmission module, a first correspondence between the first DC voltage and the output current, and a current stabilization time corresponding to each target current amplitude from the main control module; determine the current stabilization time corresponding to the target light intensity according to the target light intensity, the second correspondence and the first correspondence; and collect the reflected light signal on the surface of the sample to be tested according to the current stabilization time to determine the detection result of the sample to be tested.

[0021] Furthermore, in some embodiments of the present invention, the ellipsometric measurement module is also configured to: compare the measured light intensity amplitude of the reflected light collected from the surface of the sample to be measured with the corresponding target light intensity amplitude according to a preset time interval; and in response to the difference between the measured light intensity amplitude and the corresponding target light intensity amplitude being greater than a preset error threshold, correct the second corresponding relationship between the first DC voltage and the light intensity amplitude according to the measured light intensity amplitude.

[0022] Furthermore, in some embodiments of the present invention, the semiconductor measurement device further includes an automatic focusing system. The automatic focusing system is used to provide a fifth control instruction corresponding to the second target light intensity to the constant current power supply, and irradiate the second illumination light output by the first light source module to the surface of the sample to be measured, so as to determine the focus position of the semiconductor measurement device according to the second reflected light signal of the surface of the sample to be measured.

[0023] Furthermore, in some embodiments of the present invention, the semiconductor measurement device further includes a second light source module and an image recognition module. The second light source module is used to output a third illumination light of corresponding light intensity according to the second output current provided by the second current absorption module of the constant current power supply. The image recognition module is used to provide a sixth control instruction corresponding to the third target light intensity to the constant current power supply, filter the third illumination light output by the second light source module, and irradiate the obtained narrow-band light to the surface of the sample to be tested, so as to determine the characteristic image of the surface of the sample to be tested according to the third reflected light signal of the surface of the sample to be tested.

[0024] Furthermore, in some embodiments of the present invention, the current detection module of the constant current power supply synchronously samples the first feedback voltage of the first current absorption module and the second feedback voltage of the second current absorption module through its first differential sampling channel and the second differential sampling channel, and synchronously transmits the corresponding first output current amplitude and the second output current amplitude to the main controller module, so that the main controller module can perform synchronous negative feedback control on the first current absorption module and the second current absorption module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0026] Figure 1 A schematic structural diagram of a semiconductor measurement device provided according to some embodiments of the present invention is shown.

[0027] Figure 2A circuit framework diagram of a constant current power supply provided according to some embodiments of the present invention is shown.

[0028] Figure 3 A circuit topology diagram of a current sink module provided according to some embodiments of the present invention is shown.

[0029] Figure 4 A schematic diagram of the operating principle of a current sink module provided according to some embodiments of the present invention is shown.

[0030] Figure 5 A circuit diagram of a current detection module provided according to some embodiments of the present invention is shown.

[0031] Figure 6 A schematic diagram of a measuring unit for a sample to be tested provided according to some embodiments of the present invention is shown. DETAILED DESCRIPTION

[0032] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal" and "vertical" used in the following description should be understood as the directions shown in the paragraph and the related drawings. Such relative terms are only used for the convenience of description and do not mean that the device described therein must be manufactured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0035] It is understood that although the terms "first", "second", "third", etc. may be used herein to describe various components, regions, layers and / or parts, these components, regions, layers and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers and / or parts. Therefore, the first component, region, layer and / or part discussed below may be referred to as a second component, region, layer and / or part without departing from some embodiments of the present invention.

[0036] As mentioned above, in the design of power supply excitation circuits for ellipsometry, high-precision constant current sources are widely used due to their wide spectrum response range, fast response speed, high constant current accuracy, long-term stable operation, and suitability for loads of various properties. However, existing light sources generally have the problem that the output light intensity is easily weakened over time and the light intensity jitter is easily generated due to fluctuations in the driving current, thus affecting the stability of semiconductor measurement results.

[0037] In order to overcome the above-mentioned defects of the prior art, the present invention provides a constant current power supply and a semiconductor measurement device, which can adjust and stabilize the amplitude of the output current by setting a current self-locking current absorption module to stabilize the output light intensity of the light source module, thereby improving the stability of the semiconductor measurement results.

[0038] In some non-limiting embodiments, the constant current power supply provided by the first aspect of the present invention may be configured in the semiconductor measurement device provided by the second aspect of the present invention. Figure 1 , Figure 1 A schematic structural diagram of a semiconductor measurement device provided according to some embodiments of the present invention is shown.

[0039] exist Figure 1 In the illustrated embodiment, the semiconductor measurement device provided by the second aspect of the present invention includes a constant current power supply 10, a first light source module 20 and an ellipsometric measurement module 30. Here, the constant current power supply 10 is at least used to provide a constant first output current to the first light source module 20 according to a control instruction corresponding to a first target light intensity provided by the ellipsometric measurement module 30. The first light source module 20 can be a laser driven white light source (LDLS) or a xenon lamp, and is used to output a first illumination light corresponding to a light intensity according to a first output current provided by a first current absorption module of the constant current power supply 10. The ellipsometric measurement module 30 further performs polarization processing on the first illumination light output by the first light source module 20, and irradiates the obtained polarized light to the surface of the sample 50 to be tested, so as to determine the film thickness on the surface of the sample 50 to be tested according to a first reflected light signal on the surface of the sample 50 to be tested.

[0040] In addition, in some embodiments, the semiconductor measurement device provided by the second aspect of the present invention may also optionally include an automatic focusing system 40, which is used to provide a control instruction corresponding to a second target light intensity to the constant current power supply 10, and to irradiate the second illumination light output by the first light source module 20 to the surface of the sample to be tested 50 through multiple optical elements such as reflectors, polarization elements, color wheels and slits, so as to determine the focusing position of the semiconductor measurement device according to the second reflected light signal from the surface of the sample to be tested 50.

[0041] In addition, in some embodiments, the semiconductor measurement device provided by the second aspect of the present invention may also optionally include a second light source module 60 and a pattern recognition (PR) module 70. Here, the constant current power supply 10 is also used to provide a constant second output current to the second light source module 60 according to the control instruction corresponding to the third target light intensity provided by the image recognition module 70. The second light source module 60 may use an LED tricolor light source, and is used to output a third illumination light of corresponding light intensity through multiple optical elements such as reflectors and spectroscopes according to the second output current provided by the second current absorption module of the constant current power supply 10. The image recognition module 70 further filters the third illumination light output by the second light source module 60, and irradiates the obtained narrow-band light to the surface of the sample to be tested 50, so as to determine the characteristic image of the surface of the sample to be tested 50 according to the third reflected light signal of the surface of the sample to be tested 50, and determine the defect detection result and / or the core component parameters such as the trace width of the surface of the sample to be tested 50 based on the image characteristics.

[0042] Please refer to Figures 2 to 4 . Figure 2 A circuit framework diagram of a constant current power supply provided according to some embodiments of the present invention is shown. Figure 3 A circuit topology diagram of a current sink module provided according to some embodiments of the present invention is shown. Figure 4 A schematic diagram of the operating principle of a current sink module provided according to some embodiments of the present invention is shown.

[0043] exist Figures 2 to 4In the illustrated embodiment, the above-mentioned constant current power supply 10 provided by the first aspect of the present invention includes a current absorption module 11 and a power supply module 12. The current absorption module 11 includes a first operational amplifier 111, a second operational amplifier 112 and a field effect transistor Q. Here, the first input end of the first operational amplifier 111 is connected to the first DC voltage VIN provided externally via the external control selection interface LK1, and the second input end thereof is connected to the output end of the second operational amplifier 112, and the output end thereof is connected to the gate of the field effect transistor Q. The external control selection interface LK1 is connected to the first DC voltage VIN corresponding to the external control instruction. The first input end of the second operational amplifier 112 is connected to the drain of the field effect transistor Q and is grounded via a load resistor R, and the second input end thereof is connected to a constant voltage (for example: grounded via a 10kΩ resistor). The source of the field effect transistor Q is connected to the second DC voltage EXT of the external load via the external load interface LK2, and is used to generate an output current of corresponding amplitude at its drain according to the output voltage provided by the output terminal of the first operational amplifier 111, and provide a first feedback voltage to the first input terminal of the second operational amplifier 112 via the load resistor R, and then provide a second feedback voltage to the second input terminal of the first operational amplifier 111 via the output terminal of the second operational amplifier 112, so as to adjust and stabilize the amplitude of the output current.

[0044] Further, in some embodiments, the first operational amplifier 111 and / or the second operational amplifier 112 can use an AD8610 operational amplifier, whose noise can be as low as nV level to reduce the jitter amplitude of the input current. At the same time, the AD8610 operational amplifier has the characteristics of low input bias current, fast response speed, unity gain stability, no phase inversion and wide bandwidth, which can perform accurate measurements and avoid waveform errors. In addition, the field effect transistor Q can use a MOSFET IRF640 metal oxide semiconductor field effect transistor, which has a large drain current to improve the output response of the current absorption module 11. At the same time, the MOSFET IRF640 metal oxide semiconductor field effect transistor has the characteristics of low on-resistance, high on-efficiency, fast response speed, etc., and is suitable for a variety of high and low current application scenarios.

[0045] Furthermore, in the process of outputting a constant current, the field effect transistor Q can operate in its linear region. In this way, the output current of the current absorption module 11 will be proportional to the output voltage provided by the output terminal of the first operational amplifier 111, the first feedback voltage generated by the load resistor R will be proportional to the output current, the second feedback voltage output by the second operational amplifier 112 will be proportional to the difference between the first feedback voltage and the above-mentioned constant voltage (for example: 0V), and the output voltage provided by the output terminal of the first operational amplifier 111 will be proportional to the difference between the first DC voltage VIN and the second feedback voltage, thereby forming a current self-locking loop.

[0046] Specific as Figure 4As shown, in the process of applying a positive voltage to the first DC voltage VIN, in response to the output voltage V1 of the first operational amplifier 111 rising to above the turn-on voltage Vth of the field effect transistor Q, the field effect transistor Q turns on, and the first feedback voltage on the load resistor R increases with the increase of the output current IOUT in the loop. Correspondingly, the second feedback voltage output by the second operational amplifier 112 will also increase with the increase of the first feedback voltage, thereby reducing the difference between the first DC voltage VIN and the second feedback voltage, so as to correspondingly reduce the output voltage V1 of the first operational amplifier 111, and the adaptive balance of the voltages of each node is performed in this way until the output current IOUT reaches a constant. Here, the value of the output current IOUT is positively correlated with the first DC voltage VIN, the first amplification factor of the first operational amplifier 111, and the second DC voltage EXT, and is negatively correlated with the resistance value of the load resistor R and the second amplification factor of the second operational amplifier 112. The specific value can be adjusted autonomously according to actual needs, so it is not limited.

[0047] Further, in Figure 2 In the illustrated embodiment, the constant current power supply 10 provided by the first aspect of the present invention may further include a main controller module 13, a current detection module 14 and a data transmission module 15. The power supply module 12 may not only be used to provide the first DC voltage VIN and / or the second DC voltage EXT to the current sink module 11, but may also preferably be connected to the main controller module 13, the current detection module 14 and the data transmission module 15 via a low dropout linear regulator (LDO) unit to supply power thereto and reduce the ripple of the power supply to each module.

[0048] In addition, in some embodiments, the main controller module 13 may be a STM32 microcontroller, which is provided with a master clock for coordinating the orderly operation of each module and / or multiple units therein according to a master clock signal HCLK generated by the master clock.

[0049] Specifically, during the semiconductor measurement process, the data transmission module 15 can obtain the external control instruction indicating the target light intensity provided by the above-mentioned ellipsometric measurement module 30, the automatic focusing system 40 and / or the image recognition module 70 via an external host computer or directly from the above-mentioned ellipsometric measurement module 30, the automatic focusing system 40 and / or the image recognition module 70, and transmit the control instruction to the main controller module 13. The main controller module 13 can generate an internal control instruction indicating the target current amplitude according to the external control instruction, and transmit it to the power supply module 12 to adjust the supply voltage amplitude via its DC-DC unit, and provide a first DC voltage VIN of a corresponding amplitude to the first input terminal of the first operational amplifier 111.

[0050] In addition, the current detection module 14 can be connected to the main controller module 13 by using the SPI data transmission method based on the serial peripheral interface to meet the requirements of high-speed transmission of large data, thereby improving the real-time performance of semiconductor measurement results. The current detection module 14 is grounded via the load resistor R, and is used to collect the first feedback voltage from the load resistor R to determine the amplitude of the output current, and transmit the amplitude of the output current to the main controller module 13, so that it can perform negative feedback control on the current absorption module 11 to adjust the output current online.

[0051] In addition, the above-mentioned data transmission module 15 can adopt a data transmission method based on TTL signals to connect to the main controller module 13, and adopt a data transmission method based on USB signals to connect to an external host computer, which is used to obtain the amplitude data of the output current collected by the current detection module 14 from the main controller module 13, and transmit it to the host computer, so that the user can timely understand the actual output current of the constant current power supply 10.

[0052] Those skilled in the art will understand that the embodiments in which the main controller module 13 directly provides control instructions indicating the target current amplitude to the power module 12 are only some non-limiting implementation methods provided by the present invention, which are intended to clearly demonstrate the main concepts of the present invention and provide some specific solutions that are convenient for the public to implement, rather than to limit the scope of protection of the present invention.

[0053] Optionally, in other embodiments, the main controller module 13 can pre-calibrate the correspondence between the first DC voltage and the output current offline, and provide the first DC voltage of the corresponding amplitude according to the correspondence to achieve similar technical effects. Specifically, the main controller module 13 can provide the power module 12 with control instructions indicating multiple first DC voltages before providing control instructions to the power module 12, and obtain the corresponding output current amplitudes respectively through the current detection module 14. Afterwards, the main controller module 13 can determine the first correspondence between the first DC voltage and the output current according to the first DC voltage and the output current corresponding to each control instruction. Thereafter, the main controller module 13 can generate and provide the power module with a control instruction indicating the corresponding voltage according to the target current amplitude and the first correspondence.

[0054] Furthermore, in some embodiments, in order to prevent the output current fluctuation during the current self-locking process of the current absorption module 11 from affecting the stability of the semiconductor measurement results, the current detection module 14 can also obtain the amplitude of the output current at multiple times in response to the control instruction issued by the main controller module 13. Afterwards, the main controller module 13 can determine the current stabilization time corresponding to each target current amplitude according to the change gradient of the amplitude of the output current at multiple times. In this way, after providing the control instruction to the power supply module 12, the main controller module 13 can preferably control the current detection module 14 to collect the amplitude of the output current according to the current stabilization time corresponding to the target current amplitude, so as to avoid misjudgment and misadjustment caused by the previous current fluctuation of the current module 11, and avoid excessive waiting time affecting the efficiency of semiconductor measurement.

[0055] In addition, in some embodiments, the ellipsometric measurement module 30 is connected to the data transmission module 15 of the constant current power supply 10. Before providing the control instruction to the constant current power supply 10, the ellipsometric measurement module 30 may provide the control instruction indicating a plurality of first DC voltages to the main controller module 13 of the constant current power supply 10 via the data transmission module 15 in advance, and respectively collect the light intensity amplitude of the reflected light on the surface of the sample to be measured. Afterwards, the ellipsometric measurement module 30 may determine the second corresponding relationship between the first DC voltage and the light intensity amplitude according to the first DC voltage and the light intensity amplitude corresponding to each control instruction. Thereafter, the ellipsometric measurement module 30 may generate and provide the corresponding control instruction to the constant current power supply 10 according to the target light intensity and the second corresponding relationship.

[0056] Furthermore, in order to prevent the output current fluctuation during the current self-locking process of the current absorption module 11 from affecting the stability of the semiconductor measurement result, the ellipsometric measurement module 30 can also preferably obtain the first correspondence between the first DC voltage and the output current, and the current stabilization time corresponding to each target current amplitude from the main control module 13 via the data transmission module 15. Afterwards, in the process of semiconductor measurement, the ellipsometric measurement module 30 can first determine the current stabilization time corresponding to the target light intensity according to the target light intensity, the second correspondence and the first correspondence, and then collect the reflected light signal on the surface of the sample 50 to be tested according to the current stabilization time to determine the detection result of the sample to be tested, thereby avoiding the detection error caused by the current fluctuation of the constant current power supply 10 in the early stage.

[0057] Please refer to further Figure 5 and Figure 6 . Figure 5 A circuit diagram of a current detection module provided according to some embodiments of the present invention is shown. Figure 6 A schematic diagram of a measuring unit for a sample to be tested provided according to some embodiments of the present invention is shown.

[0058] exist Figure 5In the embodiment shown, the constant current power supply 10 preferably includes a plurality of current sink modules 11, and the current detection module 14 can select an AD7794 chip, which has a plurality of differential sampling channels AIN1±~AIN6±, for synchronously sampling the first feedback voltages of the plurality of current sink modules 11, and synchronously transmitting the corresponding output current amplitudes to the main controller module 13, so that it can synchronously negatively feedback control the respective current sink modules 11. Here, the current detection module 14 can achieve a sampling accuracy of 23 bits, its root mean square (RMS) noise is 40nV at 4.17Hz, and the typical drift value of its internal bandgap reference voltage source is 4ppm / ℃. In this way, the current detection module 15 can realize more precise, low-noise, stable and reliable feedback regulation of semiconductor measurement devices.

[0059] Furthermore, during the measurement of the semiconductor device, the current detection module 14 can synchronously sample the first feedback voltage of the first current absorption module and the second feedback voltage of the second current absorption module through its first differential sampling channel AIN1± and the second differential sampling channel AIN2±, and synchronously transmit the corresponding first output current amplitude and second output current amplitude to the main controller module 13, so that the main controller module 13 can synchronously control the first current absorption module and the second current absorption module.

[0060] Accordingly, if Figure 6 As shown, the sample to be tested 50 includes a plurality of measuring units. In the process of measuring the sample to be tested 50, the ellipsometric measurement module 30, the automatic focusing system 40 and the image recognition module 70 can alternately provide external control instructions to the constant current power supply 10, and synchronously sample and synchronously control each light source module 20, 60 through the current detection module 14 and the main controller module 13, so as to perform multi-dimensional measurement of film thickness, surface defects and / or characteristic component parameters for each measuring unit one by one. By coordinating the above-mentioned pre-calibrated current stabilization time, the ellipsometric measurement module 30 and the image recognition module 70 are alternately used to collect the reflected light signal on the surface of the sample to be tested 50. The present invention can quantitatively determine the timing of collecting the reflected light signal each time, so as to take into account the efficiency of semiconductor measurement and the stability of the measurement results, thereby avoiding the problem of low measurement efficiency and poor consistency of measurement results caused by batch detection of the film thickness, surface defects and / or characteristic component parameters of each unit.

[0061] In addition, in some embodiments, in order to prevent the output light intensity of the first light source module 20 from weakening over time, the ellipsometer module 30 may also compare the measured light intensity amplitude of the reflected light collected from the surface of the sample 50 to be tested with the corresponding target light intensity amplitude according to a preset time interval. Afterwards, in response to the difference between the measured light intensity amplitude and the corresponding target light intensity amplitude being greater than a preset error threshold, the ellipsometer module 30 may also preferably correct the second corresponding relationship between the first DC voltage and the light intensity amplitude according to the measured light intensity amplitude, thereby automatically correcting the detection error caused by the aging and weakening of the light source and improving the service life of the light source.

[0062] In summary, the above-mentioned constant current power supply and semiconductor measuring device provided by the present invention can adjust and stabilize the amplitude of the output current by setting a current absorption module with negative feedback control to stabilize the light source brightness of the light source module, thereby improving the stability of the semiconductor measuring device during the measurement process.

[0063] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0064] Those skilled in the art will appreciate that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips cited throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0065] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0066] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A constant current power supply, characterized in that: The invention comprises a current absorption module, wherein the current absorption module comprises: A first operational amplifier, wherein a first input terminal thereof is connected to a first DC voltage provided externally, a second input terminal thereof is connected to an output terminal of a second operational amplifier, and an output terminal thereof is connected to a gate of a field effect transistor; The second operational amplifier has a first input terminal connected to the drain of the field effect transistor and grounded via a load resistor, and a second input terminal connected to a constant voltage; and The field effect transistor has a source connected to an external second DC voltage, and is used to generate an output current of corresponding amplitude at its drain according to the output voltage provided by the output terminal of the first operational amplifier, and provide a first feedback voltage to the first input terminal of the second operational amplifier via the load resistor, and then provide a second feedback voltage to the second input terminal of the first operational amplifier via the output terminal of the second operational amplifier, so as to adjust and stabilize the amplitude of the output current.

2. The constant current power supply according to claim 1, characterized in that: The field effect transistor operates in its linear region, the output current is proportional to the output voltage provided by the output terminal of the first operational amplifier, the first feedback voltage is proportional to the output current, the second feedback voltage is proportional to the difference between the first feedback voltage and the constant voltage, and the output voltage provided by the output terminal of the first operational amplifier is proportional to the difference between the first DC voltage and the second feedback voltage.

3. The constant current power supply according to claim 2, characterized in that: Also includes: A power supply module is used to provide the first DC voltage and / or the second DC voltage to the current sink module.

4. The constant current power supply according to claim 3, characterized in that: Also includes: A main controller module is connected to the power module and is used to provide a first control instruction indicating a target current amplitude to the power module, so as to provide a first DC voltage of a corresponding amplitude to the first input terminal of the first operational amplifier via the power module.

5. The constant current power supply according to claim 4, characterized in that: Also includes: The current detection module is connected to the main controller module and grounded via the load resistor, and is used to collect the first feedback voltage to determine the amplitude of the output current, and transmit the amplitude of the output current to the main controller module for negative feedback control of the current absorption module.

6. The constant current power supply according to claim 5, characterized in that: The main controller module is also configured to: Before providing the first control instruction to the power module, providing the power module with a second control instruction indicating a plurality of first DC voltages in advance, and obtaining the corresponding output current amplitudes respectively through the current detection module; determining a first corresponding relationship between the first DC voltage and the output current according to the first DC voltage and the output current corresponding to each of the second control instructions; as well as According to the target current amplitude and the first corresponding relationship, a corresponding first control instruction is generated and provided to the power module.

7. The constant current power supply according to claim 6, characterized in that: The current detection module also obtains the amplitude of the output current at multiple moments in response to the second control instruction issued by the main controller module, and the main controller module is further configured as follows: Determining the current stabilization time corresponding to each target current amplitude according to the change gradient of the output current amplitude at multiple moments; as well as After providing the first control instruction to the power module, the current detection module is controlled to collect the amplitude of the output current according to the current stabilization time corresponding to the target current amplitude.

8. The constant current power supply according to claim 7, characterized in that: Also includes: A data transmission module is connected to the main controller module and an external host computer, and is used to transmit a third control instruction indicating the target current amplitude provided by the host computer to the main controller module, and to transmit the amplitude data of the output current collected by the current detection module from the main controller module to the host computer.

9. The constant current power supply according to claim 8, characterized in that: The current detection module and the main controller module use a SPI data transmission method based on a serial peripheral interface, and / or The main controller module and the data transmission module use a data transmission method based on TTL signals, and / or The data transmission module and the host computer use a data transmission method based on USB signals.

10. The constant current power supply according to claim 5, characterized in that: The constant current power supply includes multiple current absorption modules, and the current detection module uses AD7794 chip, which has multiple differential sampling channels for synchronously sampling the first feedback voltages of multiple current absorption modules and synchronously transmitting the corresponding output current amplitudes to the main controller module for synchronous negative feedback control of each current absorption module.

11. The constant current power supply according to claim 4, characterized in that: The first operational amplifier and / or the second operational amplifier are AD8610 operational amplifiers, and / or The field effect transistor is a MOSFETIRF640 metal oxide semiconductor field effect transistor, and / or The main controller module uses an STM32 single-chip microcomputer.

12. A semiconductor measurement device, characterized in that: include: The constant current power supply according to any one of claims 1 to 11, at least used to provide a constant first output current for a first light source module of the semiconductor measurement device; The first light source module is used to output a first illumination light of corresponding light intensity according to the first output current provided by the first current absorption module of the constant current power supply; as well as The ellipsometric measurement module is used to provide a third control instruction corresponding to the first target light intensity to the constant current power supply, polarize the first illumination light output by the first light source module, and irradiate the obtained polarized light to the surface of the sample to be tested, so as to determine the film thickness of the surface of the sample to be tested based on the first reflected light signal of the surface of the sample to be tested.

13. The semiconductor measurement device according to claim 12, wherein: The ellipsometric measurement module is connected to the data transmission module of the constant current power supply and is configured as follows: Before providing the third control instruction to the constant current power supply, providing a fourth control instruction indicating a plurality of first DC voltages to a main controller module of the constant current power supply via the data transmission module in advance, and respectively collecting the light intensity amplitudes of the reflected light on the surface of the sample to be tested; Determine a second corresponding relationship between the first DC voltage and the light intensity amplitude according to the first DC voltage and the light intensity amplitude corresponding to each of the fourth control instructions; as well as According to the target light intensity and the second corresponding relationship, a corresponding third control instruction is generated and provided to the constant current power supply.

14. The semiconductor measurement device according to claim 13, wherein: The ellipsometric measurement module is further configured as follows: Acquire, from the main control module via the data transmission module, a first corresponding relationship between the first DC voltage and the output current, and a current stabilization time corresponding to each target current amplitude; Determining a current stabilization time corresponding to the target light intensity according to the target light intensity, the second corresponding relationship and the first corresponding relationship; as well as The reflected light signal on the surface of the sample to be tested is collected according to the current stabilization time to determine the detection result of the sample to be tested.

15. The semiconductor measurement device according to claim 13, wherein: The ellipsometric measurement module is further configured as follows: According to a preset time interval, the measured light intensity amplitude of the reflected light collected from the surface of the sample to be tested is compared with the corresponding target light intensity amplitude; as well as In response to the difference between the measured light intensity amplitude and the corresponding target light intensity amplitude being greater than a preset error threshold, the second corresponding relationship between the first DC voltage and the light intensity amplitude is corrected according to the measured light intensity amplitude.

16. The semiconductor measurement device according to claim 12, wherein: Also includes: The automatic focusing system is used to provide a fifth control instruction corresponding to the second target light intensity to the constant current power supply, and irradiate the second illumination light output by the first light source module to the surface of the sample to be tested, so as to determine the focusing position of the semiconductor measurement device according to the second reflected light signal from the surface of the sample to be tested.

17. The semiconductor measurement device according to claim 16, wherein: Also includes: A second light source module, used for outputting a third illumination light of corresponding light intensity according to a second output current provided by the second current absorption module of the constant current power supply; as well as An image recognition module is used to provide a sixth control instruction corresponding to a third target light intensity to the constant current power supply, filter the third illumination light output by the second light source module, and irradiate the obtained narrow-band light onto the surface of the sample to be tested, so as to determine a characteristic image of the surface of the sample to be tested based on a third reflected light signal of the surface of the sample to be tested.

18. The semiconductor measurement device according to claim 17, wherein: The current detection module of the constant current power supply synchronously samples the first feedback voltage of the first current absorption module and the second feedback voltage of the second current absorption module through its first differential sampling channel and the second differential sampling channel, and synchronously transmits the corresponding first output current amplitude and second output current amplitude to the main controller module, so that the main controller module can perform synchronous negative feedback control on the first current absorption module and the second current absorption module.

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