CN114865444B - Excimer laser dose precision control method and system and excimer laser - Google Patents
Excimer laser dose precision control method and system and excimer laserInfo
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- CN114865444B CN114865444B CN202210511297.2A CN202210511297A CN114865444B CN 114865444 B CN114865444 B CN 114865444B CN 202210511297 A CN202210511297 A CN 202210511297A CN 114865444 B CN114865444 B CN 114865444B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/1305—Feedback control systems
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/131—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
- H01S3/134—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the active medium, e.g. by controlling the processes or apparatus for excitation in gas lasers
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Abstract
本发明公开了一种准分子激光器剂量精度控制方法及系统。该方法至少包括如下步骤：S3：判断脉冲位置是否大于预设值n，如果小于等于则进入S4；如果大于则进入S5；S4：进行单脉冲能量稳定性控制计算，得到放电腔的当前放电电压Vi j,用于控制放电腔；然后进入S6；S5：进行剂量精度控制计算，得到放电腔的当前放电电压Vi j，用于控制放电腔；然后进入S6；S6：基于当前放电电压Vi j调整放电腔的放电电压。本发明能够抑制单脉冲能量和剂量引起的波动，保证激光器工作过程中的剂量精度要求。
The present invention discloses a method and system for controlling the dose accuracy of an excimer laser. The method includes at least the following steps: S3: determining whether the pulse position is greater than a preset value n; if so, proceeding to S4; if so, proceeding to S5; S4: performing a single-pulse energy stability control calculation to obtain the current discharge voltage Vij of the discharge cavity, which is used to control the discharge cavity; then proceeding to S6; S5: performing a dose accuracy control calculation to obtain the current discharge voltage Vij of the discharge cavity, which is used to control the discharge cavity; then proceeding to S6; S6: adjusting the discharge voltage of the discharge cavity based on the current discharge voltage Vij. The present invention can suppress fluctuations caused by single-pulse energy and dose, ensuring dose accuracy requirements during laser operation.
Description
Technical Field
The invention relates to a method for controlling the dosage precision of an excimer laser, and also relates to a system for controlling the dosage precision of the excimer laser, and also relates to a corresponding excimer laser, belonging to the technical field of excimer lasers.
Background
Excimer lasers always suffer from single pulse energy fluctuations and average pulse energy drift due to factors such as preheating, gas degradation or renewal, and run time, in addition to energy overshoot (overshot). The random fluctuation of the light-emitting energy of the laser easily causes uneven exposure lines in the working process of the photoetching machine, reduces the yield and improves the production cost of enterprises. Meanwhile, due to the limitation of the service life of the gas in the laser, the stability of the light output energy can be more difficult to control along with the increase of the pulse number, and the production required dosage precision can not be ensured. Therefore, in order to improve the accuracy of the light-emitting dosage of the excimer laser, a precise and reasonable design control algorithm is required, so that the excimer laser can work for a long time under the condition of meeting the dosage accuracy requirement.
In a chinese patent application filed earlier by the applicant (publication No. CN113783099 a), an excimer laser dose control method and apparatus based on deep GRU is disclosed. The method comprises the steps of selecting a time interval after each burst mode laser pulse energy sequence is sent out by an excimer laser, judging whether the absolute value of the sliding average value difference of a current burst mode laser pulse energy loss function and a previous burst mode laser pulse energy loss function is smaller than a threshold value by using a depth-gating circulation network, updating training parameters of the depth-gating circulation network if the absolute value of the sliding average value difference is larger than the threshold value, obtaining updated values of dose control parameters, applying the updated values to dose precision control of the next burst mode laser pulse energy sequence, and applying the dose control parameters used for dose precision control of the current burst mode laser pulse energy sequence to dose precision control of the next burst mode laser pulse energy sequence if the absolute value of the sliding average value difference is smaller than the threshold value. The method has strong adaptability to different target energies and repetition frequencies, can well control the dosage precision of the excimer laser, and effectively control the dosage stability of the laser pulse energy.
Disclosure of Invention
The invention aims to provide a method for controlling the dosage precision of an excimer laser.
Another technical problem to be solved by the present invention is to provide a dose precision control system for an excimer laser.
Another technical problem to be solved by the present invention is to provide a corresponding excimer laser.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
According to a first aspect of an embodiment of the present invention, there is provided a method for controlling dose accuracy of an excimer laser, including the steps of:
S3, judging whether the pulse position is larger than a preset value n, if so, entering a step S4, and if so, entering a step S5;
s4, performing single pulse energy stability control calculation to obtain the current discharge voltage V ij of the discharge cavity, which is used for controlling the discharge cavity;
S5, performing dose precision control calculation to obtain the current discharge voltage V ij of the discharge cavity, which is used for controlling the discharge cavity, and then entering step S6;
And S6, adjusting the discharge voltage of the discharge cavity based on the current discharge voltage V ij.
Preferably, the dose accuracy control calculation includes a variable that increases the discharge voltage of the discharge chamber with an increase in burst signal, and a variable that increases the discharge voltage of the discharge chamber with an increase in pulse position in one burst signal.
Preferably, the dose accuracy control calculation is calculated based on an energy fluctuation voltage variation value for suppressing energy fluctuation of the current pulse and a dose fluctuation voltage variation value for suppressing dose fluctuation of the current pulse.
Preferably, the dose fluctuation voltage variation value is adjusted in a nonlinear amplification or reduction mode according to the dose difference value of the previous pulse position, and the energy fluctuation voltage variation value is adjusted in a nonlinear amplification or reduction mode according to the energy difference value of the previous pulse position.
Preferably, the dose accuracy control calculation is further calculated based on a predetermined current pulse voltage, wherein the current pulse voltage is calculated according to an actual measurement voltage and light emitting energy of the test discharge.
Preferably, the current pulse voltage is a preset value, and is kept unchanged under the same working condition.
Preferably, the current pulse voltage is obtained by adopting the following method under the same working condition:
a. under the condition of pre-estimating the current gas, the corresponding pre-estimated discharge voltage range is at the expected light-emitting energy;
b. Setting step sizes in the estimated discharge voltage range, adopting an incremental method to discharge at the voltage position of each step size, and averaging the light energy output by a plurality of pulses at the back of each burst to obtain an energy average value;
c. And b, selecting the nearest expected energy value in the energy average value in the step b, and obtaining a discharge voltage corresponding to the nearest expected energy value as the current pulse voltage of the next pulse under the current gas condition.
Preferably, in the calculation of the stability control of the monopulse energy, in the same burst signal, the increment of the discharge voltage of the discharge cavity is an index of the difference between the actual light-emitting energy and the expected light-emitting energy.
According to a second aspect of embodiments of the present invention, there is provided an excimer laser dose accuracy control system comprising a high voltage discharge assembly, a discharge chamber, a laser parameter measurement assembly and a dose accuracy controller,
The high-voltage discharge assembly sends excitation voltage to the discharge cavity, laser is emitted from the discharge cavity, and the laser parameter measuring assembly detects the light-emitting energy value of the discharge cavity and feeds the light-emitting energy value back to the dose precision controller.
According to a third aspect of embodiments of the present invention, there is provided an excimer laser comprising the excimer laser dose accuracy control system described above.
Compared with the prior art, the method has the following technical effects that based on a control algorithm of a discharge output energy process, influences of different pulse positions and gas lives on a discharge light-emitting process are considered, the excitation voltage is subjected to nonlinear calculation in a feedback mode, fluctuation caused by single pulse energy and dosage is restrained, severe change of the discharge voltage caused by abrupt change of the single pulse energy is avoided, and dosage precision requirements in the working process of a laser are ensured.
Drawings
FIG. 1 is a schematic diagram of a system for controlling the dose accuracy of an excimer laser according to an embodiment of the present invention;
FIG. 2 is a graph showing an example of the light output energy of a pulse sequence within a burst of an excimer laser in a constant voltage mode in accordance with an embodiment of the present invention;
FIG. 3A is a block flow diagram of a method for controlling the dose accuracy of an excimer laser according to an embodiment of the present invention;
FIG. 3B is a logic diagram of a method for controlling the dose precision of an excimer laser according to an embodiment of the present invention;
Fig. 4 is a schematic diagram showing the practical effect of the method for controlling the dose accuracy of an excimer laser according to an embodiment of the present invention.
Detailed Description
The technical contents of the present invention will be described in detail with reference to the accompanying drawings and specific examples.
It should be noted that the present invention may be used in dual cavity lasers as well as in single cavity lasers. When the method is used for a dual-cavity laser, the method for controlling the dose precision of the excimer laser can be used for adjusting the discharge voltage of a power amplification discharge cavity, and when the method is used for a single-cavity laser, only one discharge cavity is arranged, so that the method for controlling the dose precision of the excimer laser provided by the embodiment of the invention is used for adjusting the discharge voltage of the discharge cavity. The following description is only presented in terms of the scenario in which the invention is applied to a single cavity laser, but this does not constitute any limitation on the scope of the invention.
As shown in fig. 1, taking a single-cavity excimer laser as an example, the excimer laser dose precision control system provided in the embodiment of the invention includes a high-voltage discharge assembly 1, a discharge cavity 2, a laser parameter measurement assembly 3, and a dose precision controller 4.
The dose precision controller 4 receives preset expected pulse energy 101, generates a discharge voltage signal for a discharge cavity and sends the discharge voltage signal to the high-voltage discharge assembly 1 according to the dose precision control method of the excimer laser provided by the embodiment of the invention, the high-voltage discharge assembly 1 sends excitation voltage 103 to the discharge cavity 2, laser is emitted by the discharge cavity 2, and the laser parameter measuring assembly 3 detects the light-emitting energy value of the discharge cavity 2 and feeds the light-emitting energy value back to the dose precision controller 4. Thus, the accurate control of the real-time light-emitting dosage is realized by a feedback mechanism.
As is well known, excimer lasers typically emit in Burst mode, with multiple pulses, e.g., 2000 pulse positions, within a Burst at a constant excitation voltage. A typical light-emitting energy trend for each pulse position is illustrated in fig. 2. As can be seen from fig. 2, in the light extraction sequence in one burst, the light extraction energy at the front pulse position is stronger than that at the rear pulse position, and the light extraction energy at the rear pulse position is gradually stabilized. It follows that in burst mode of operation, the light output capability of an excimer laser is related to the pulse position.
Moreover, as described above, as the gas inside the excimer laser is consumed, the energy of the emitted light changes. Therefore, in order to improve the light-emitting energy stability and the dosage accuracy of the excimer laser, the invention provides a dosage accuracy control method of the excimer laser, which combines the light-emitting energy change caused by different gas conditions and the light-emitting energy change caused by different pulse positions.
As shown in fig. 3A, the method for controlling the dose precision of the excimer laser at least comprises the following steps:
S1, counting the current burst sequence;
Assuming that the current burst is the ith burst, the burst sequence is counted such that i=i+1.
S2, counting pulse positions of single pulses;
assuming that the current burst is the j-th pulse of the i-th burst, the pulse position count for a single pulse is such that j=j+1. Assuming there are N pulses in a burst, j+.n, N < N.
S3, judging whether the pulse position is larger than a preset value n, if so, entering a step S4, and if so, entering a step S5;
S4, performing single pulse energy stability control calculation to obtain the current discharge voltage V ij of the discharge cavity, which is used for controlling the discharge of the discharge cavity;
s5, performing dose precision control calculation to obtain the current discharge voltage V ij of the discharge cavity, which is used for controlling the discharge of the discharge cavity;
S6, controlling the discharge cavity based on the current discharge voltage V ij;
s7, judging whether the pulses are in the same burst or not, if so, returning to the step S2, and if not, returning to the step S1.
Referring to fig. 3B, and shown in formula (1), the method for controlling the dose precision of an excimer laser according to the embodiment of the present invention includes two parts, i.e., energy stability control in the first n pulses and pulse dose precision control in the subsequent pulses in a burst signal. Based on the voltage of the pulse corresponding to the previous burst position, the light-emitting energy at the previous n pulse positions in the current burst signal can be quickly stabilized to be close to the preset expected pulse energy by utilizing the control method of the stability of the energy of the previous n pulses, and the influence of the subsequent pulse positions and gas consumption on the light-emitting capacity is comprehensively considered at the pulse positions after the n pulses by utilizing the pulse dose precision control, so that the voltage calculated by feedback is amplified, and the dose precision of the excimer laser is not reduced due to the gas consumption.
The first section, the energy stability control step for the first n pulses, is described first.
An independent control method is employed for the first n pulses within each burst, unlike the control method for the subsequent pulses. Wherein n is selected in advance according to the characteristics of the light energy emitted by the laser. In the first n pulses, the discharge voltage of the discharge chamber of the j-th pulse in the i+1th burst is:
Wherein V i+1,j is the discharge voltage at the j (j≤n) pulse position in the i+1th burst signal (burst), V i,j is the discharge voltage at the j pulse position in the i-th burst, E i,j is the actual light-emitting energy corresponding to the j-th pulse of the i-th burst, E d is the desired light-emitting energy, k fp and c fp are preset coefficients, sign () represents a sign function.
As can be seen from the above equation, in the process of calculating the stability control of the single pulse energy, in the front and rear burst signals, the increment of the discharge voltage of the discharge cavity takes the difference between the actual light-emitting energy and the expected light-emitting energy as an index. Therefore, when the actual light emission energy of the j-th pulse in the i+1th burst is smaller than the expected light emission energy, the discharge voltage of the discharge chamber of the j+1th pulse in the i+2th burst calculated by the formula (2) increases, whereas when the actual light emission energy of the j-th pulse in the i+1th burst is larger than the expected light emission energy, the discharge voltage of the discharge chamber of the j-th pulse in the i+2th burst calculated by the formula (2) decreases. And the discharge voltage of the discharge cavity is feedback controlled according to the actual light-emitting energy of the first n pulses in different burst signals, so that the light-emitting energy of the discharge cavity is quickly stabilized to be near the expected light-emitting energy.
This control method takes advantage of the light emission characteristics of excimer lasers, as shown in fig. 2, where the light emission energy of the first n pulses 73 (assuming that pulse 72 in fig. 2 is the nth pulse) is generally higher than the expected light emission energy in a burst, the use of equation (1) will quickly stabilize in the preceding pulse (e.g., pulse 73 in fig. 2). .
Next, pulse dose accuracy control after the nth pulse is described.
As can be seen from fig. 2, the light output energy of the subsequent pulse (e.g., pulse 71 in fig. 2) after the nth pulse (pulse 72 in fig. 2) is relatively stable. But in steady state the monopulse energy remains substantially fluctuating around the expected light output energy. Moreover, as the gas degenerates, the light output energy decreases as the burst signal increases after the excimer laser has been exposed for a longer period of time. For this light emission characteristic, the dose accuracy control calculation in the embodiment of the present invention includes two variables, 1) a variable that increases the discharge voltage of the discharge chamber with an increase in burst sequence, and 2) a variable that increases the discharge voltage of the discharge chamber with an increase in pulse position in one burst.
As shown in the formula (1), the current pulse voltage V now is a voltage at which the light emission energy of the current pulse can substantially satisfy the desired light emission energy. The substantial satisfaction refers to a fluctuation range of the expected light emission energy allowed in actual use. Under long-time discharge conditions, the pulse voltage increases with an increase in the number of bursts due to deterioration of the gas conditions. In a short time (first M bursts, M is a preset value) from the beginning of the discharge chamber light emission, the discharge voltage of the discharge chamber may be set to the current pulse voltage V now, and the current pulse voltage V now remains unchanged (under the same working condition).
Under the same working condition, the current pulse voltage V now is obtained by adopting the following method:
a. Estimating upper and lower limits of control voltage (discharge voltage) of a corresponding discharge cavity at expected light-emitting energy under the current gas condition, namely estimating a discharge voltage range;
b. Setting voltage intervals (step sizes) in a pre-estimated discharge voltage range, adopting an incremental method to discharge at the voltage position of each step size, and taking an average value of light energy out of the last Y pulses (Y is a preset value, for example Y=200) of each burst to obtain an energy average value, wherein X is a preset value, for example X=100, on the assumption that X bursts are discharged;
c. And b, selecting the nearest expected energy value in the energy average value in the step b, and obtaining a discharge voltage corresponding to the nearest expected energy value as the current pulse voltage of the next pulse under the current gas condition.
In general, the current pulse voltage V now is obtained by performing test discharge after laser debugging and calculating according to the measured voltage and the light-emitting energy of the test discharge, and once the current pulse voltage V now is determined, the current pulse voltage V now is not changed under the condition that the gas condition is not changed (except for natural gas consumption caused by discharge).
Since the dose accuracy under consideration is related to the single pulse energy stability, it is necessary to compromise both single pulse (individual pulses within a burst) energy fluctuations and dose fluctuations while controlling the dose accuracy of a burst. For the j+1th pulse in the pulse sequence of j > n in the same burst signal, the voltage fluctuation caused by the j+1th pulse energy is restrained by using an energy fluctuation voltage variation value delta V p,j+1, and the voltage fluctuation caused by the j+1th pulse dose is restrained by using a dose fluctuation voltage variation value delta V d,j+1.
The energy fluctuation voltage variation value δv p,j+1 for suppressing the energy fluctuation of the current pulse is expressed as:
Wherein δv p,j+1 is an energy fluctuation voltage variation value for suppressing the j+0th pulse energy fluctuation, k p1,kp2,cp1 and c p2 are preset coefficients for adjusting the rate of change of δv p,j+1, err pint,j is an integrated value of the single pulse energy error at the j-th pulse position within the same burst, its initial value is 0;E d is a desired energy value, and E j is the single pulse energy at the j-th pulse position within the same burst.
Since the light emission mode of the laser is discrete light emission, the calculation of the integrated value err pint,j requires a discrete integration method using a zero-order holder zoh (zero-order-hold). The update of the integral value of the monopulse energy error is thus as follows:
errpint,j+1＝errpint,j+(Ed-Ej)·T (4)
Where T is the sampling period of the energy sensor of the light-emitting energy of the discharge chamber.
As can be seen from equations (3) and (4), the energy fluctuation voltage variation δv p,j+1 is adjusted in a nonlinear manner in accordance with the energy difference at the previous pulse position.
Similarly, the voltage variation δv d,j+1 for suppressing the dose fluctuation is expressed as:
Where δv d,j+1 is a dose fluctuation voltage variation value for suppressing dose fluctuation of the j+1th pulse, D d is a desired dose, D j is an actual dose at the j-th pulse position, k d1,kd2,cd1, and c d2 are preset coefficients, err dint,j represents a dose error integration value at the j-th pulse position, expressed as:
errdint,j+1＝errdint,j+(Dd-Dj+1)·T (6)
as can be seen from equations (5) and (6), the dose ripple voltage variation δv d,j+1 is adjusted in a non-linear manner, either up or down, depending on the dose difference at the previous pulse position.
Inside the same burst, the pulse position is relatively back, and the corresponding gas light-emitting capability is relatively weak. Similarly, the more the position is, the weaker the light extraction capability is for different burst arrays. Considering the impact of pulse position and gas life comprehensively, the discharge voltage of the discharge cavity corresponding to the j-th pulse of the i-th burst is as follows:
Where α is the partition coefficient (preset value) for single pulse energy stability control and dose accuracy control, β 1 (j) is a function of the internal pulse position of one burst, β 2 (i) is a function of the burst array, and for β 1 (j) and β 2 (i), the following calculation methods may be selected, or other calculation methods may be used.
Where c 1 and c 2 are preset coefficients, j denotes the j-th pulse, and i denotes the i-th burst signal.
In the continuous light emission process, the increment of the discharge voltage of the discharge cavity is approximately exponentially increased along with the increase of the burst sequence (i.e. the increase of the i value) as shown in the formulas (7) and (9), and the increment of the discharge voltage of the discharge cavity is approximately multiply increased along with the increase of the pulse position in one burst as shown in the formulas (7) and (8). Therefore, the invention rapidly compensates the light emission dosage reduction caused by gas degradation (such as exponential change), and compensates the single pulse energy fluctuation, the average pulse energy drift and the energy overshoot at a slow speed (such as multiple level change) relative to the former, thereby taking account of the light emission energy change caused by two reasons, and further obtaining higher dosage accuracy control effect.
In order to verify the technical effect of the method for controlling the dose precision of the excimer laser provided by the embodiment of the invention, the technical effect can be obtained through simulation analysis, and under the condition that the working condition is unchanged (for example, 248nm KrF excimer laser model works at the repetition frequency of 4KHz, the target energy is set to be 10 mJ), the energy stability and the dose stability can reach the optimal control effect by adjusting parameters, and as can be known from fig. 4, the dose precision of each burst signal is controlled to be below 0.3%.
In summary, according to the excimer laser dose precision control method provided by the embodiment of the invention, based on the control algorithm of the discharge output energy process, the influence of different pulse positions and gas lives on the discharge light-emitting process is considered, the feedback mode is utilized to perform nonlinear calculation on the excitation voltage, meanwhile, fluctuation caused by single pulse energy and dose is restrained, severe change of the discharge voltage caused by abrupt change of the single pulse energy is avoided, and the dose precision requirement in the laser working process is ensured.
The method and the system for controlling the dosage precision of the excimer laser, provided by the invention, are described in detail above. Any obvious modifications to the present invention, without departing from the spirit thereof, would constitute an infringement of the patent rights of the invention and would take on corresponding legal liabilities.
Claims (9)
1. The method for controlling the dosage precision of the excimer laser is characterized by comprising the following steps:
S1, counting the current burst sequence;
S2, counting pulse positions of single pulses;
S3, judging whether the pulse position is larger than a preset value n, if so, entering a step S4, and if so, entering a step S5;
S4, performing single pulse energy stability control calculation to obtain the current discharge voltage Vij of the discharge cavity for controlling the discharge cavity, and then entering step S6;
S5, performing dose precision control calculation to obtain the current discharge voltage Vij of the discharge cavity, and controlling the discharge cavity, and then entering step S6;
S6, adjusting the discharge voltage of the discharge cavity based on the current discharge voltage Vij;
S7, judging whether the pulses are in the same burst or not, if so, returning to the step S2, and if not, returning to the step S1;
The dose accuracy control calculation includes a variable that increases the discharge voltage of the discharge chamber with an increase in burst signal, and a variable that increases the discharge voltage of the discharge chamber with an increase in pulse position in one burst signal.
2. The method for controlling the dose precision of an excimer laser according to claim 1, wherein the dose precision control calculation is based on an energy fluctuation voltage variation value for suppressing energy fluctuation of the current pulse and a dose fluctuation voltage variation value for suppressing dose fluctuation of the current pulse.
3. The method of controlling the dose precision of an excimer laser according to claim 2, wherein the dose fluctuation voltage variation is adjusted in a nonlinear manner by increasing or decreasing the dose difference value of the previous pulse position, and the energy fluctuation voltage variation is adjusted in a nonlinear manner by increasing or decreasing the energy difference value of the previous pulse position.
4. The method for controlling the dose precision of an excimer laser according to claim 2, wherein the dose precision control calculation is further performed based on a predetermined current pulse voltage calculated from an actual measurement voltage of a test discharge and an emission energy.
5. The method of controlling the dose precision of an excimer laser according to claim 4, wherein the current pulse voltage is a preset value and remains unchanged under the same operating condition.
6. The method for controlling the dose precision of the excimer laser according to claim 5, wherein the current pulse voltage is obtained by a method of estimating a corresponding estimated discharge voltage range at a desired light emission energy under a current gas condition;
b. Setting step sizes in the estimated discharge voltage range, adopting an incremental method to discharge at the voltage position of each step size, and averaging the light energy output by a plurality of pulses at the back of each burst to obtain an energy average value;
c. And b, selecting the nearest expected energy value in the energy average value in the step b, and obtaining a discharge voltage corresponding to the nearest expected energy value as the current pulse voltage of the next pulse under the current gas condition.
7. The method for controlling the dose precision of an excimer laser according to claim 5, wherein:
in the single pulse energy stability control calculation, in the same burst signal, the increment of the discharge voltage of the discharge cavity takes the difference between the actual light-emitting energy and the expected light-emitting energy as an index.
8. The excimer laser dose precision control system is characterized by comprising a high-voltage discharge assembly, a discharge cavity, a laser parameter measurement assembly and a dose precision controller, wherein the dose precision controller receives preset expected pulse energy, generates a discharge voltage signal for the discharge cavity according to the excimer laser dose precision control method of any one of claims 1-7 and sends the discharge voltage signal to the high-voltage discharge assembly, the high-voltage discharge assembly sends excitation voltage to the discharge cavity, laser is emitted by the discharge cavity, and the laser parameter measurement assembly detects the light-emitting energy value of the discharge cavity and feeds the light-emitting energy value back to the dose precision controller.
9. An excimer laser comprising the excimer laser dose precision control system of claim 8.
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