Analog signal processing system for a lithography machine

Abstract

Provided is an analog signal processing system of a lithography machine, comprising: a transconductance circuit for receiving a current signal output by a current mode sensor and converting it into a voltage signal; a differential circuit for receiving the voltage signal and a reference supply voltage output by a reference supply circuit and performing a difference to output a differential voltage; an analog multiplier circuit for multiplying the differential voltage by an output gain to obtain an analog multiplication output signal with spectrum shifted to a predetermined carrier frequency; a band-pass filter for filtering low frequency noise in the analog multiplication output signal to obtain a first filtered signal; and a digital multiplier circuit for multiplying the first filtered signal by a digital reference signal in phase and frequency with the output gain to obtain a digital multiplication output signal. In this way, signal shifting to a predetermined carrier frequency can achieve physical noise isolation, and noise energy can be suppressed through modulation-multiplication-demodulation.

Description

Technical Field

[0001] This application relates to the field of lithography machine technology, and more specifically, to an analog signal processing system for a lithography machine. Background Technology

[0002] Photolithography machines are crucial equipment in semiconductor manufacturing. Their function is to precisely transfer circuit patterns from a photomask (also known as a photomask) to a wafer or other substrate according to predetermined dimensions and positions using an exposure process. Specifically, the exposure system of the photolithography machine accurately projects and exposes the integrated circuit patterns on the photomask onto a silicon wafer coated with photoresist using optical imaging, directly determining the lithography resolution, overlay accuracy, production efficiency, and process window.

[0003] In the exposure system of a lithography machine, the uniformity of illumination is mainly used to monitor and calibrate the light intensity uniformity and stability of the exposure light source to ensure uniform exposure energy distribution on the wafer surface. In traditional circuits, the uniformity of illumination is connected to a data acquisition board via a long transmission line to collect the sensor's values, which are then transmitted to the main control chip for subsequent data processing. Its control scheme is open-loop control, directly converting the sensor's analog signal into a digital signal. However, it is particularly sensitive to noise; any noise in the sensor's output will be converted into quantization, which is detrimental to the processing of small signals (useful signals are easily buried in noise).

[0004] Furthermore, because the uniform illuminance sensor is a current-type sensor, its output signal is relatively small, and the long transmission line is susceptible to interference from surrounding electromagnetic equipment, resulting in significant noise in the sensor, with the noise frequency being quite close to the detection signal frequency. Moreover, hardware filtering cannot effectively remove noise surrounding the sensor signal, and therefore cannot effectively measure the exposure energy distribution on the wafer surface.

[0005] Therefore, given the presence of noise with similar frequencies in the detection signal, it is desirable to provide an improved analog signal processing system for lithography machines to reduce ambient noise interference. Summary of the Invention

[0006] This application provides an analog signal processing system for a lithography machine, which transfers the signal to a predetermined carrier frequency to achieve physical noise isolation and suppresses noise energy through modulation-multiplication-demodulation to obtain a useful output signal that is synchronized and coherent with the reference signal.

[0007] According to one aspect of this application, an analog signal processing system for a lithography machine is provided, comprising: a transconductance circuit for receiving a current signal output from a current-type sensor and converting it into a voltage signal; a differential circuit for receiving the voltage signal output from the transconductance circuit and a reference power supply voltage output from a reference power supply circuit, and performing a difference between the voltage signal and the reference power supply voltage to output a differential voltage; an analog multiplier circuit for multiplying the differential voltage by an output gain to obtain an analog multiplication output signal with its spectrum shifted to a predetermined carrier frequency; a bandpass filter for filtering out low-frequency noise in the analog multiplication output signal to obtain a first filtered signal; and a digital multiplier circuit for multiplying the first filtered signal by a digital reference signal that is in phase and at the same frequency as the output gain to obtain a digital multiplication output signal.

[0008] The analog signal processing system of the aforementioned lithography machine further includes a current-type sensor for outputting a current signal.

[0009] In the analog signal processing system of the aforementioned lithography machine, the current-type sensor is an illuminance sensor.

[0010] The analog signal processing system of the aforementioned lithography machine further includes: a reference power supply circuit for outputting a reference power supply voltage.

[0011] The analog signal processing system of the aforementioned lithography machine further includes: a logic control unit for controlling the output gain of the analog multiplier circuit.

[0012] In the analog signal processing system of the aforementioned lithography machine, the output gain is And the predetermined carrier frequency is .

[0013] The analog signal processing system of the aforementioned lithography machine further includes a low-pass filter for filtering out high-frequency noise in the digital multiplication output signal to obtain a DC output signal.

[0014] In the analog signal processing system of the aforementioned lithography machine, the differential voltage is , Corresponding to the useful signal output by the current-type sensor, Corresponding to the noise signal generated by the surrounding electromagnetic interference of the current-type sensor, and the DC output signal is .

[0015] In the analog signal processing system of the aforementioned lithography machine, the analog multiplier circuit is an analog-to-digital converter circuit, and the digital multiplier circuit is a digital-to-analog converter circuit.

[0016] In the analog signal processing system of the aforementioned lithography machine, the transconductance circuit, the reference power supply circuit, the differential circuit, the analog multiplier circuit, the bandpass filter, and the digital multiplier circuit are located on the front panel, which is connected to the current sensor via a coaxial cable.

[0017] The analog signal processing system for a lithography machine provided in this application embodiment can achieve physical noise isolation by transferring the signal to a predetermined carrier frequency, and suppress noise energy through modulation-multiplication-demodulation to obtain a useful output signal that is synchronized and coherent with the reference signal. Attached Figure Description

[0018] Various other advantages and benefits of this application will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0019] Figure 1 The illustration shows a schematic configuration of the analog signal processing system of a lithography machine according to an embodiment of this application.

[0020] Figure 2 The illustration shows a schematic diagram of an example configuration of an analog signal processing system for a lithography machine according to an embodiment of this application.

[0021] Figure 3 The illustration shows a schematic diagram of an example of the front-panel circuit configuration of the analog signal processing system of a lithography machine according to an embodiment of this application. Detailed Implementation

[0022] Detailed Description of Embodiments. Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0023] Figure 1 The illustration shows a schematic configuration of the analog signal processing system of a lithography machine according to an embodiment of this application. Figure 1As shown, in response to the problem that the transmitted signal of a current-type sensor is easily affected by surrounding electromagnetic interference, resulting in high signal noise, in the analog signal processing system of the lithography machine according to the embodiment of this application, the current-type sensor 100, such as a uniform illuminance sensor, is connected to the front panel 200 via a coaxial cable. The front panel 200 includes a transconductance circuit 210, a reference power supply circuit 220, a differential circuit 230, an analog multiplier circuit 240, a bandpass filter 250, and a digital multiplier circuit 260.

[0024] Specifically, the signal output by the current-type sensor 100, such as the uniform illuminance sensor, is a current, which is converted into a voltage signal through the transconductance circuit 210. Due to the presence of a complex magnetic field in the surrounding environment, the voltage signal is differentially divided with the voltage output by the reference power supply circuit 220 in the differential circuit 230 to reduce common-mode noise in the circuit. However, this is not enough to effectively eliminate the influence of other noises on the sensor output.

[0025] Here, it is assumed that the electrical signal output by the current-type sensor 100 after passing through the transconductance circuit 210 and the differential circuit 230 is... ,in The useful signal output by the sensor. If the noise signal generated by the sensor due to surrounding electromagnetic interference is connected to the gain terminal of the analog multiplier circuit 240, then the output signal is connected to the gain terminal of the sensor.

[0026] The output gain of the analog multiplier circuit 240 is (Carrier wave), which can be set by the logic control unit, then the final output of the analog multiplier circuit 240 is: That is, the final output of the analog multiplier circuit 240 It scales the input digital value by multiplying the analog voltage by the gain control voltage, thereby shifting the spectrum of the useful signal and noise signal to the carrier frequency. .thus, After passing through a bandpass filter 250 (whose center frequency is...) This allows the signal output from the differential circuit 230 to be filtered out. Low-frequency noise that remains and is not completely removed during the modulation process. In contrast, this is impossible in traditional schemes because the low-frequency noise completely overlaps with the signal in the frequency domain.

[0027] Assuming the output after passing through a bandpass filter of 250 is Then it is connected to the input terminal of the digital multiplier circuit 260. Here, the digital multiplier circuit 260 samples the... The high-frequency signal centered on it, even if some new high-frequency noise is introduced in the transmission path, its energy is usually much lower than the previous low-frequency noise. Therefore, the data collected by the digital multiplier circuit 260 is... The digital form of the signal is in phase and frequency with the digital reference signal generated within the logic control unit and whose output gain is in sync with that of the analog multiplier circuit 240. Multiplying them again, the result is: Regarding the signal section Using the identity: We can obtain: It contains a DC component With high frequency components .

[0028] Regarding the noise component When noise is multiplied by a relevant reference signal, due to their lack of correlation, the result is still a signal distributed in... It eliminates nearby broadband noise without producing a significant DC component.

[0029] Optionally, The input is fed into a low-pass filter, for example, which may be located inside the logic control unit to obtain the DC component. Other high-frequency noises are filtered out, effectively eliminating the influence of noise in the circuit. Here, the low-pass filter is implemented through a logic control unit, such as an FPGA, and the low-pass filtering can be implemented by changing the programming code as needed.

[0030] In the analog signal processing system of the lithography machine according to embodiments of this application, the analog multiplier circuit 240 and the digital multiplier circuit 270 can be implemented as a DAC (digital-to-analog converter) circuit and an ADC (analog-to-digital converter) circuit, respectively, with a large input range and a wide frequency coverage. Furthermore, the logic control unit can employ an FPGA (Field-Programmable Gate Array) or other more complex logic control units, such as a DSP (Digital Signal Processor) / CPLD (Complex Programmable Logic Device).

[0031] here, Figure 2 The illustration shows a schematic diagram of an example configuration of an analog signal processing system for a lithography machine according to an embodiment of this application. Figure 2As shown, when a DAC module circuit is used as an analog multiplier circuit, and the gain output of the DAC module circuit is controlled by an FPGA module circuit, the influence of frequency noise near the useful signal can be effectively filtered out by utilizing the principle of signal correlation. Furthermore, long-distance transmission often uses digital signals to avoid electromagnetic interference.

[0032] Therefore, the analog signal processing system of the lithography machine according to the embodiments of this application includes: a transconductance circuit for receiving a current signal output by a current-type sensor and converting it into a voltage signal; a differential circuit for receiving the voltage signal output by the transconductance circuit and a reference power supply voltage output by a reference power supply circuit, and performing a difference between the voltage signal and the reference power supply voltage to output a differential voltage; an analog multiplier circuit for multiplying the differential voltage by an output gain to obtain an analog multiplication output signal with its spectrum shifted to a predetermined carrier frequency; a bandpass filter for filtering out low-frequency noise in the analog multiplication output signal to obtain a first filtered signal; and a digital multiplier circuit for multiplying the first filtered signal by a digital reference signal that is in phase and at the same frequency as the output gain to obtain a digital multiplication output signal.

[0033] Furthermore, the analog signal processing system of the aforementioned lithography machine further includes a current-type sensor for outputting current signals.

[0034] Furthermore, in the analog signal processing system of the aforementioned lithography machine, the current-type sensor is an illuminance sensor.

[0035] Furthermore, the analog signal processing system of the aforementioned lithography machine further includes a reference power supply circuit for outputting a reference power supply voltage.

[0036] Furthermore, the analog signal processing system of the aforementioned lithography machine further includes a logic control unit for controlling the output gain of the analog multiplier circuit.

[0037] Furthermore, in the analog signal processing system of the aforementioned lithography machine, the output gain is And the predetermined carrier frequency is .

[0038] Furthermore, the analog signal processing system of the aforementioned lithography machine further includes: a low-pass filter for filtering out high-frequency noise in the digital multiplication output signal to obtain a DC output signal. Furthermore, in the analog signal processing system of the aforementioned lithography machine, the differential voltage is , Corresponding to the useful signal output by the current-type sensor, Corresponding to the noise signal generated by the surrounding electromagnetic interference of the current-type sensor, and the DC output signal is .

[0039] Furthermore, in the analog signal processing system of the aforementioned lithography machine, the analog multiplier circuit is an analog-to-digital converter circuit, and the digital multiplier circuit is a digital-to-analog converter circuit.

[0040] Furthermore, in the analog signal processing system of the aforementioned lithography machine, the transconductance circuit, the reference power supply circuit, the differential circuit, the analog multiplier circuit, the bandpass filter, and the digital multiplier circuit are located on the front panel, which is connected to the current sensor via a coaxial cable.

[0041] Figure 3 The illustration shows a schematic diagram of an example of the front-panel circuit configuration of the analog signal processing system of a lithography machine according to an embodiment of this application.

[0042] like Figure 3 As shown, the front-end board consists of a reference power supply module, a differential module, a DAC module, a bandpass filter, and an ADC module. Specifically, the front-end board's input power supply is 15V, with capacitors C4 and C5 filtering out power supply noise. The reference power supply chip U7 (AD587) has an input of 15V and an output (pin 6 of U7) of 10V. The 10V output voltage is routed in two directions: one path passes through a follower (U8 AD744KRZ) to isolate interference between the preceding and following stages, and is connected to the ADC module as a reference source; the other path passes through a voltage divider formed by resistors R6 and R7 to obtain a 100mV voltage (OFSET) for subsequent differential circuitry. I-ESS represents the output current of the uniform illuminance sensor. After passing through the transconductance circuit module, the output signal is a voltage V-ESS, where the relationship between V-ESS and I-ESS is, for example, V-ESS(V) = 5000 * I-ESS(A).

[0043] The V-ESS is isolated from the interaction between the transconductance circuit and the differential circuit module by a follower (U5A AD711KRZ). Similarly, the reference voltage OFST is also separated from the interaction between the preceding and following stages by a follower (U2A AD711KRZ). The V-ESS and OFST are differentially processed to obtain the signal Vout1. Vout1 is input to the RF pin of the DAC module for the DAC output gain. The final output of the DAC is the sum of Vout1 and the input carrier sinusoidal signal (…). The product of the two signals is fed into a bandpass filter to filter out low-frequency noise that remains or is not completely removed during modulation. The output of the bandpass filter is connected to the input of the ADC to demodulate the signal and obtain the magnitude of the sensor's output signal.

[0044] Therefore, in the analog signal processing system of the lithography machine according to the embodiments of this application, the input power supply of the front board is 15V, which is input to the reference power chip after the power supply noise is filtered out by the capacitor. The output voltage of the reference power chip is 10V, which includes the reference power supply voltage of 100mV after voltage division by resistors and the reference voltage of the analog multiplier circuit.

[0045] Furthermore, in the analog signal processing system of the aforementioned lithography machine, the reference power supply voltage, the reference voltage of the analog multiplier circuit, and the voltage signal output by the transconductance circuit are isolated from interference between the preceding and following stages by a follower.

[0046] Thus, the analog signal processing system of the lithography machine according to the embodiments of this application can actively move the signal away to the high-frequency region where low-frequency noise is not significant, achieving physical noise isolation. Only useful signals that are completely synchronized and coherent with the reference signal can generate a stable DC component after demodulation. Random and unrelated noise is greatly dispersed and suppressed after the series of operations of "modulation-multiplication-demodulation".

[0047] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0048] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0049] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0050] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0051] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An analog signal processing system for a lithography machine, comprising: Transconducting circuit, used to receive the current signal output by the current-type sensor and convert it into a voltage signal; A differential circuit is used to receive a voltage signal output from a transconductance circuit and a reference power supply voltage output from a reference power supply circuit, and to perform a differential voltage output by dividing the voltage signal and the reference power supply voltage. An analog multiplier circuit is used to multiply the differential voltage by the output gain to obtain an analog multiplication output signal with a spectrum shifted to a predetermined carrier frequency; A bandpass filter is used to filter out low-frequency noise in the analog multiplication output signal to obtain a first filtered signal; as well as, A digital multiplier circuit is used to multiply the first filtered signal by a digital reference signal that is in phase and frequency with the output gain to obtain a digital multiplication output signal.

2. The analog signal processing system for the lithography machine as described in claim 1, further comprising: A current-type sensor is used to output a current signal.

3. The analog signal processing system for a lithography machine as described in claim 2, wherein, The current-type sensor is an illuminance sensor.

4. The analog signal processing system for the lithography machine as described in claim 2, further comprising: A reference power supply circuit is used to output a reference power supply voltage.

5. The analog signal processing system for the lithography machine as described in claim 4, further comprising: A logic control unit is used to control the output gain of the analog multiplier circuit.

6. The analog signal processing system for a lithography machine as described in claim 1, wherein, The output gain is And the predetermined carrier frequency is .

7. The analog signal processing system for the lithography machine as described in claim 1, further comprising: A low-pass filter is used to filter out high-frequency noise in the digital multiplication output signal to obtain a DC output signal.

8. The analog signal processing system for a lithography machine as described in claim 7, wherein, The differential voltage is , Corresponding to the useful signal output by the current-type sensor, Corresponding to the noise signal generated by the surrounding electromagnetic interference of the current-type sensor, and the DC output signal is .

9. The analog signal processing system for a lithography machine as described in claim 1, wherein, The analog multiplier circuit is an analog-to-digital converter circuit, and the digital multiplier circuit is a digital-to-analog converter circuit.

10. The analog signal processing system for a lithography machine as described in claim 1, wherein, The transconducting circuit, the reference power supply circuit, the differential circuit, the analog multiplier circuit, the bandpass filter, and the digital multiplier circuit are located on the front panel, which is connected to the current sensor via a coaxial cable.

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