Analog signal processing system of photoetching machine
By introducing components such as transconductance circuits, differential circuits, analog multiplier circuits, and bandpass filters into the lithography machine, noise isolation of the signal is achieved, solving the problem of severe noise interference in traditional lithography machines and improving the stability and accuracy of signal processing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-03-10
Smart Images
Figure CN121634725A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of photoetching machines, and more particularly to an analog signal processing system of a photoetching machine. BACKGROUND
[0002] A photoetching machine is an important device in a semiconductor manufacturing process, and its function is to accurately transfer a circuit pattern in a mask plate (also referred to as a photomask plate) to a wafer or other substrate according to a predetermined size and position through an exposure process. The exposure system of the photoetching machine is used to accurately project and expose an integrated circuit pattern on the mask plate to a silicon wafer coated with photoresist through optical imaging, and directly determines the photoetching resolution, overlay accuracy, production efficiency and process window.
[0003] In the exposure system of the photoetching machine, the uniformity sensor is mainly used to monitor and calibrate the light intensity uniformity and stability of the exposure light source to ensure that the exposure energy distribution on the wafer surface is uniform. In the traditional circuit, the uniformity sensor is connected to the acquisition board card through a long transmission line, the value of the uniformity sensor is collected, and then transmitted to the main control chip for subsequent data processing. The control scheme is open-loop control, which directly converts the analog quantity of the sensor into digital quantity, but it is particularly sensitive to noise, and any noise output by the sensor will be converted into quantization, which is not conducive to the processing of small signals (useful signals are easily buried in noise).
[0004] Moreover, because the uniformity sensor is a current sensor, the long transmission line is easy to be disturbed by the surrounding electromagnetic equipment, resulting in a large noise of the detected uniformity sensor, and the noise frequency is close to the detection signal frequency. Moreover, the hardware filter cannot effectively filter the noise around the sensor signal, and cannot effectively measure the exposure energy distribution on the wafer surface.
[0005] Therefore, in view of the noise with close frequency in the detection signal, it is expected to provide an improved analog signal processing system of a photoetching machine for reducing the interference of surrounding noise. SUMMARY
[0006] The embodiment of the present application provides an analog signal processing system of a photoetching machine, which transfers the signal to a predetermined carrier frequency to realize physical noise isolation, suppresses noise energy through modulation-multiplication-demodulation, so as to obtain a useful output signal which is synchronous and coherent with a reference signal.
[0007] According to an aspect of the present application, there is provided an analog signal processing system of a lithography machine, comprising: a transconductance circuit configured to receive a current signal output by a current sensor and convert the current signal into a voltage signal; a difference circuit configured to receive the voltage signal output by the transconductance circuit and a reference supply voltage output by a reference supply circuit, and perform a difference between the voltage signal and the reference supply voltage to output a difference voltage; an analog multiplier circuit configured to multiply the difference voltage by an output gain to obtain an analog multiplication output signal having a frequency spectrum shifted to a predetermined carrier frequency; a band-pass filter configured to filter out low frequency noise in the analog multiplication output signal to obtain a first filtered signal; and a digital multiplier circuit configured to multiply the first filtered signal by a digital reference signal having a same frequency and a same phase as the output gain to obtain a digital multiplication output signal.
[0008] In the analog signal processing system of the lithography machine, the current sensor is further configured to output a current signal.
[0009] In the analog signal processing system of the lithography machine, the current sensor is a uniformity sensor.
[0010] In the analog signal processing system of the lithography machine, the reference supply circuit is further configured to output a reference supply voltage.
[0011] In the analog signal processing system of the lithography machine, the logic control unit is further configured to control the output gain of the analog multiplier circuit.
[0012] In the analog signal processing system of the lithography machine, the output gain is , and the predetermined carrier frequency is .
[0013] In the analog signal processing system of the lithography machine, the low-pass filter is further configured to filter out high frequency noise in the digital multiplication output signal to obtain a direct current output signal.
[0014] In the analog signal processing system of the lithography machine, the difference voltage is , a useful signal corresponding to the current sensor output, a noise signal generated by the current sensor due to surrounding electromagnetic interference, and the direct current output signal is .
[0015] In the analog signal processing system of the lithography machine, the analog multiplier circuit is an analog-to-digital conversion circuit, and the digital multiplier circuit is a digital-to-analog conversion circuit.
[0016] In the analog signal processing system of the above lithography machine, the transconductance circuit, the reference power supply circuit, the differential circuit, the analog multiplier circuit, the band-pass filter and the digital multiplier circuit are located on the preamplifier board, and the preamplifier board is connected to the current-mode sensor through a coaxial cable.
[0017] The analog signal processing system of the lithography machine provided by the embodiments of the present application can realize physical noise isolation by transferring signals to a predetermined carrier frequency, and can suppress noise energy by modulation-multiplication-demodulation, so as to obtain a useful output signal which is synchronous and coherent with a reference signal. BRIEF DESCRIPTION OF DRAWINGS
[0018] The various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiments. The accompanying drawings are intended to only illustrate preferred embodiments of the present application and are consequently not to be considered limiting of its scope. Obviously, other drawings than those described below can be derived from the drawings described below without paying creative labor, and the drawings described below are only some embodiments of the present application. Moreover, the same reference numerals are used to denote the same components throughout the drawings.
[0019] Figure 1 FIG. 1 illustrates a schematic configuration diagram of an analog signal processing system of a lithography machine according to an embodiment of the present application.
[0020] Figure 2 FIG. 1 illustrates a schematic configuration diagram of an analog signal processing system of a lithography machine according to an embodiment of the present application.
[0021] Figure 3 FIG. 1 illustrates a schematic configuration diagram of an analog signal processing system of a lithography machine according to an embodiment of the present application. DETAILED DESCRIPTION
[0022] DETAILED DESCRIPTION. Hereinafter, example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments of the present application, and it should be understood that the present application is not limited to the described example embodiments.
[0023] Figure 1 FIG. 1 illustrates a schematic configuration diagram of an analog signal processing system of a lithography machine according to an embodiment of the present application. As 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 250 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 2The DAC module circuit is used as an analog multiplier circuit, and the gain output of the DAC module circuit is controlled by the FPGA module circuit. In this case, the signal correlation principle can be used to effectively filter out the influence of frequency noise near the useful signal. At the same time, digital signals are usually used for long-distance transmission to avoid electromagnetic interference.
[0032] Therefore, the analog signal processing system of the photolithography machine according to the embodiment of the present application comprises: a transconductance circuit configured to receive a current signal output by a current sensor and convert the current signal into a voltage signal; a difference circuit configured to receive the voltage signal output by the transconductance circuit and a reference power supply voltage output by a reference power supply circuit, and perform a difference between the voltage signal and the reference power supply voltage to output a difference voltage; an analog multiplier circuit configured to multiply the difference voltage by an output gain to obtain an analog multiplication output signal whose frequency spectrum is shifted to a predetermined carrier frequency; and a band-pass filter configured to filter out low-frequency noise in the analog multiplication output signal to obtain a first filtered signal; and a digital multiplier circuit configured to multiply the first filtered signal by a digital reference signal which is the same in frequency and in phase as the output gain to obtain a digital multiplication output signal.
[0033] In addition, in the analog signal processing system of the photolithography machine, the current sensor is further configured to output a current signal.
[0034] In addition, in the analog signal processing system of the photolithography machine, the current sensor is a uniform illuminance sensor.
[0035] In addition, in the analog signal processing system of the photolithography machine, the reference power supply circuit is further configured to output a reference power supply voltage.
[0036] In addition, in the analog signal processing system of the photolithography machine, the logic control unit is further configured to control the output gain of the analog multiplier circuit.
[0037] In addition, in the analog signal processing system of the photolithography machine, the output gain is , and the predetermined carrier frequency is .
[0038] In addition, in the analog signal processing system of the photolithography machine, the low-pass filter is further configured to filter out high-frequency noise in the digital multiplication output signal to obtain a direct current output signal In addition, in the analog signal processing system of the photolithography machine, the difference voltage is , corresponding to a useful signal output by the current sensor, corresponding to a noise signal generated by the current sensor due to surrounding electromagnetic interference, and the direct current 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 photolithography machine according to the embodiment of the present application, the input power of the board card of the preamplifier board is 15V, and the reference power chip is input after filtering the power noise by a capacitor, and the output voltage of the reference power chip is 10V, including the reference power voltage of 100mV after resistance voltage division and the reference voltage of the analog multiplier circuit.
[0045] In addition, in the analog signal processing system of the photolithography machine, the reference power voltage, the reference voltage of the analog multiplier circuit and the voltage signal output by the transconductance circuit are isolated from the interference of the front and rear stages by a follower.
[0046] Therefore, the analog signal processing system of the photolithography machine according to the embodiment of the present application can actively move the signal to the high frequency region where the low frequency noise is not significant, realize physical noise isolation, and only the useful signal completely synchronized and coherent with the reference signal can produce stable direct current component after demodulation, and the random and incoherent noise is greatly dispersed and suppressed after the series of operations of "modulation-multiplication-demodulation".
[0047] The above describes the basic principles of the present application in combination with specific embodiments, but it should be pointed out that the advantages, advantages, effects and the like mentioned in the present application are only examples and not limitations, and these advantages, advantages, effects and the like cannot be considered as the must-have of each embodiment of the present application. In addition, the above specific details are only for the purpose of example and for the purpose of understanding, and the above details do not limit the present application to the above specific details.
[0048] The block diagrams of the devices, apparatuses, equipment, systems involved in the present application are only illustrative examples and are not intended to require or imply that the connection, arrangement, configuration must be as shown in the block diagram. As those skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any way. Words such as "include", "contain", "have" and the like are open-ended words, which mean "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.
[0049] It should also be noted that in the devices, equipment and methods of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombination should be considered as equivalent solutions of the present application.
[0050] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
[0051] The above description has been presented to enable any person skilled in the art to make or use the application. Numerous modifications to the aspects described herein will be readily apparent to those skilled in the art, and the principles defined herein can be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An analog signal processing system of a lithography machine, comprising: a transconductance circuit for receiving a current signal outputted by a current-mode sensor and converting into a voltage signal; a difference circuit for receiving the voltage signal outputted by the transconductance circuit and a reference supply voltage outputted by a reference supply circuit, and performing a difference between the voltage signal and the reference supply voltage to output a difference voltage; an analog multiplier circuit for multiplying the difference voltage by an output gain to obtain an analog multiplication output signal with a spectrum shifted to a predetermined carrier frequency; a band-pass 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 in-phase with the output gain to obtain a digital multiplication output signal.
2. The analog signal processing system of a lithography machine of claim 1, further comprising: a current-mode sensor for outputting a current signal. The current-mode sensor is a uniformity sensor.
3. The analog signal processing system for a lithography machine as set forth in claim 2, wherein, a reference supply circuit for outputting a reference supply voltage.
4. The analog signal processing system for a lithography machine of claim 2, further comprising: a logic control unit for controlling the output gain of the analog multiplier circuit.
5. The analog signal processing system for a lithography machine of claim 4, further comprising:
7. The analog signal processing system of a lithography machine of claim 1, further comprising:
6. The analog signal processing system for a lithography machine as set forth in claim 1, wherein, The output gain is , and the predetermined carrier frequency is . a low-pass filter for filtering out high-frequency noise in the digital multiplication output signal to obtain a direct current output signal. The analog multiplier circuit is an analog-to-digital conversion circuit, and the digital multiplier circuit is a digital-to-analog conversion circuit.
8. The analog signal processing system for a lithography machine as set forth in claim 7, wherein, The differential voltage is , The useful signal corresponding to the current sensor output, The noise signal corresponding to the current sensor generated by the surrounding electromagnetic interference, and the direct current output signal is .
9. The analog signal processing system for a lithography machine as set forth in claim 1, wherein, The transconductance circuit, the reference supply circuit, the difference circuit, the analog multiplier circuit, the band-pass filter, and the digital multiplier circuit are located on a preamplifier board, and the preamplifier board is connected to the current-mode sensor through a coaxial cable.
10. The analog signal processing system for a lithography machine as set forth in claim 1, wherein,