CN116610007B

CN116610007B - Mask alignment lithography apparatus, illumination system and illumination method thereof

Info

Publication number: CN116610007B
Application number: CN202310876087.8A
Authority: CN
Inventors: 张惠; 黄逊志; 刘功振; 周星
Original assignee: Shanghai Lieth Precision Equipment Co ltd
Current assignee: Shanghai Lieth Precision Equipment Co ltd
Priority date: 2023-07-18
Filing date: 2023-07-18
Publication date: 2023-10-27
Anticipated expiration: 2043-07-18
Also published as: CN116610007A

Abstract

The invention provides a mask alignment lithography apparatus, an illumination system and an illumination method thereof, wherein the illumination system comprises: a light source module for providing illumination required for lithography; the light condensing module is used for condensing the light emitted by the light source module; the diaphragm adjusting module is used for providing clear aperture and angular spectrum required in the photoetching task; the light homogenizing module is used for homogenizing the light passing through the diaphragm adjusting module; the telecentric optical system is used for guiding the light subjected to light equalization to the mask plate; an electronic control system for providing power to each module of the lighting system; and a master control system for controlling the respective modules of the lighting system to perform operations during lighting, wherein the light source module includes a UV-LED lamp bead in which one or more wavelength type dies are encapsulated, each wavelength type includes one or more dies connected in parallel with each other, and the dies of each wavelength type are independently controlled by the electronic control system.

Description

Mask alignment lithography apparatus, illumination system and illumination method thereof

Technical Field

The present invention relates to the field of semiconductor manufacturing, and more particularly, to a mask alignment lithographic apparatus, an illumination system and an illumination method thereof.

Background

The lithography machine is one of the necessary equipment for integrated circuit production, and the illumination system is a core component in the lithography machine system. The resolution of the lithography machine is related to the illumination wavelength, the numerical aperture of the projection objective and the process coefficient according to the resolution formula of the lithography machine. Under the condition that the projection objective and the process coefficient are certain, shortening the illumination wavelength is a method for directly and effectively improving the resolution of the photoetching machine. To improve lithographic resolution, the illumination system operates at wavelengths ranging from the conventional mercury lamp illumination lines G (436 nm), H (405 nm), I (365 nm) to KrF (248 nm), arF (193 nm), to extreme ultraviolet EUV (13.5 nm). While resolution enhancement is performed by shortening the illumination wavelength, corresponding annular illumination, off-axis illumination, etc. techniques are also applied to the illumination system to further enhance the resolution of the lithography system by illumination methods.

For subsequent lithography systems, the lithographic resolution is generally on the order of micrometers, so shorter operating wavelengths do not need to be pursued in terms of illumination, but the source of illumination is required to have a sufficiently high energy, a sufficiently uniform illumination value over the exposure surface, while considering the characteristics of the photoresist, it is generally required that the illumination system have a mixed spectrum of at least two.

For subsequent photolithography systems, particularly contact/proximity lithography machines, high pressure mercury lamps are typically used as the light source, while microlens arrays are used for light uniformity. As described in patent Illumination System of a Microlithographic Contact and Proximity Exposure Apparatus of SUSS corporation of germany (EP 2253997 A2), an illumination system is described, which uses a mercury lamp as a light source, an ellipsoidal reflector as a light collector of the mercury lamp, and then light equalization of the light path is achieved by two optical integrators, and the system has two disadvantages, namely, a high-voltage mercury lamp is used as the light source, potential safety hazard is caused, and meanwhile, the power is high; secondly, an ellipsoidal reflector is adopted, the focal position of the ellipsoidal reflector is a homogenizer, but the focal position is high in temperature, so that the heat dissipation and refrigeration of the system are difficult.

Furthermore, in U.S. patent light Illumination Device (US 4497015), an optical illumination device is described, which also uses a mercury lamp as an illumination light source, and uses a double fly-eye lens as an optical homogenizer, so that fly eyes can perform light uniformization, but the unit of each fly eye cannot be made small, so that the light uniformization effect is inferior to that of a microlens array. A lighting system is designed based on a mercury lamp light source in paper Micro-Optics for Photolithography (DOI: 10.1002/opph.20150030), and two optical integrators are adopted in the lighting system for light equalizing. In the paper "Homogeneous LED-illumination Using Microlens Arrays" (DOI: 10.1117/12.618747) an LED is used as a light source, and a lens is used to collect and collimate the light emitted from the LED, which cannot realize mixed spectrum illumination.

As can be seen from the above cited prior art, existing illumination systems all require an integrator or an optical homogenizer for homogenizing the light intensity, so that the outgoing light becomes more uniform. However, because the mercury lamp is used for illumination, the divergence angle is larger, and the energy at the second focus is more concentrated, continuous refrigeration is required, and two times of light intensity homogenization are generally required to ensure that the light intensity uniformity of the exposure surface meets the use requirement. In addition, because the radiation spectrum of the mercury lamp is wider, when the mercury lamp is used as a light source, other invalid spectrums in the mercury lamp need to be filtered out, so that power consumption is caused, and meanwhile, the filtered spectrums need to be subjected to heat dissipation, so that the system is relatively complex. Meanwhile, the high-pressure mercury lamp needs to be lightened at high pressure, and high-pressure gas is filled in the high-pressure mercury lamp, so that certain potential safety hazards exist. On the other hand, when an LED is used as a light source, it cannot efficiently achieve fusion of multispectral, and thus cannot effectively match the needs of a photoresist. In addition, the conventional illuminometer performs sensitivity calibration only for individual wavelengths, so that a suitable matching wavelength cannot be found at the time of mixing wavelengths, and thus the detection accuracy cannot be further improved.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In view of the above problems, the present invention provides an illumination system for a mask alignment lithography apparatus, which uses a UV-LED as an illumination light source and can realize a function of mixing spectra, and can make the light intensity uniformity of an exposure surface meet the use requirement by only adopting a light homogenizing process once, and simultaneously, its control system stores sensitivity parameters of a plurality of illuminometers, and can automatically calculate equivalent wavelengths when mixing wavelengths, thereby improving the detection accuracy of illuminance. The system has simple structure and rich functions, and can meet the use requirement of a mask alignment photoetching machine.

According to an aspect of the invention, there is provided an illumination system for a mask alignment lithographic apparatus, comprising: a light source module for providing illumination required for lithography; the light condensing module is used for condensing the light emitted by the light source module; the diaphragm adjusting module is used for providing clear aperture and angular spectrum required in the photoetching task; the light homogenizing module is used for homogenizing the light passing through the diaphragm adjusting module; the telecentric optical system is used for guiding the light subjected to light equalization to the mask plate; an electronic control system for providing power to each module of the lighting system; and a master control system for controlling the respective modules of the lighting system to perform operations during lighting, wherein the light source module includes a UV-LED lamp bead in which one or more wavelength type dies are encapsulated, each wavelength type includes one or more dies connected in parallel with each other, and the dies of each wavelength type are independently controlled by the electronic control system.

According to a further embodiment of the invention, the diaphragm adjustment module further comprises: a diaphragm disc provided with a clear aperture and an angular spectrum filter of various sizes and rotatable about a central rotation axis; and a rotating motor for driving the diaphragm disc to rotate about the central rotation axis to different aperture positions.

According to a further embodiment of the invention, the lighting system further comprises an illuminance detection module, the illuminance detection module further comprising: an illuminance sensor for detecting illuminance of light emitted from the telecentric optical system; and a second illuminance sensor for detecting illuminance of light at the surface of the mask plate.

According to a further embodiment of the invention, the master control system is further configured to perform a sensitivity calibration procedure for the first illuminance sensor, the sensitivity calibration procedure comprising: the main control system controls the electric control system to enable only one wavelength crystal grain in the light source module to work and emit light; reading an illuminance detection result of the second illuminance sensor; the main control system calculates and adjusts the sensitivity of the first illuminance sensor under the wavelength according to the detection result of the second illuminance sensor so that the reading of the first illuminance sensor is consistent with the reading of the second illuminance sensor; repeating the steps with a preset wavelength step length in the working wavelength region of the light source module; and storing the calibrated sensitivity value in the master control system.

According to a further embodiment of the invention, the master control system is configured to control the respective modules of the lighting system to perform any one of the following lighting modes of operation, the lighting modes of operation comprising: a constant current mode, a constant illuminance operation mode, a constant dose operation mode, a time-sharing exposure mode, and a wavelength-division exposure mode.

According to a further embodiment of the invention, the master control system is further configured to: for the radiation illuminance values of different wavelengths, according to the proportion of the radiation illuminance values of the set wavelengths, the equivalent wavelength of the mixed wavelength is automatically calculated; searching a sensitivity value corresponding to the wavelength which is the same as or similar to the equivalent wavelength in the stored sensitivity data of the illuminance sensor; and setting a first illuminance sensor according to the sensitivity value, and performing the outgoing illuminance detection.

According to a further embodiment of the invention, the master control system is further configured to: monitoring the working state of the crystal grain in the light source module, comprising: estimating the current contribution of each crystal grain of each wavelength according to the number of crystal grains of each wavelength and the sum of the crystal grain currents of the wavelength in normal operation; during operation, monitoring the current variation; and deducing the number of failed grains based on the value of the current variation and the current contribution of the individual grains; and adjusting an operating parameter of the light source module based on the inferred number of failed dies.

According to a further embodiment of the invention, the lighting system further comprises: the heat dissipation module is used for dissipating heat of the light source module; and a temperature sensor for monitoring the temperature of the light source module and reporting to the master control system, and the master control system is further configured to perform corresponding temperature control measures according to the temperature reported by the temperature sensor.

According to a further aspect of the invention there is provided a mask alignment lithographic apparatus comprising an illumination system as in the invention.

According to a further aspect of the invention, there is provided a lighting method implemented by a lighting system as in the invention, the lighting method comprising: calibrating a first illuminance sensor of the lighting system; determining an operating mode of the lighting system and related parameter settings; determining a clear aperture and an angular spectrum mode, and correspondingly adjusting a diaphragm adjusting module; and performing exposure according to the determined operation mode and the related parameter settings.

Compared to prior art illumination systems, the inventive UV-LED illumination system for a mask alignment lithographic apparatus has at least the following advantages and technical effects:

1. the illumination system of the invention can easily provide control modes such as constant current, constant illumination, constant dosage and the like, provide exposure modes such as time-sharing exposure, wavelength-division exposure and the like, and can change the clear aperture and the angular spectrum type in each mode. The combination of the control mode, the exposure mode, the aperture type and the like can realize rich illumination combination modes and wider photoetching application;

2. illuminance detection calibration is performed for all wavelengths within the operating wavelength range, so that when the mixed wavelength is operated, high-precision illuminance detection can be realized by finding out the sensitivity of the same or similar matched wavelengths in the master control system;

3. the main control system can realize real-time monitoring of each wavelength grain in the UV-LED lamp beads and deduce the number of fault grains, so that the maximum power value which can be realized can be more accurately estimated, and the fault of a light source caused by overhigh power setting is avoided;

4. the crystal grains with various wavelengths in the light source are individually electrically controlled, and a plurality of crystal grains in the same wavelength are connected in parallel, so that after one or more crystal grains in the light source fail, other crystal grains can still work normally, the whole light source can not be replaced after one crystal grain fails, and the cost is effectively saved.

These and other features and advantages will become apparent upon reading the following detailed description and upon reference to the associated drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed.

Drawings

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this invention and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a schematic diagram of an illumination system for a mask alignment lithographic apparatus according to one embodiment of the invention.

Fig. 2 is a schematic diagram illustrating die arrangement within a heavy lamp bead of an illumination system according to one embodiment of the invention.

Fig. 3 is an electronically controlled schematic diagram for controlling a die according to one embodiment of the present disclosure.

Fig. 4 is a schematic diagram of a diaphragm disc layout according to one embodiment of the present disclosure.

Fig. 5 is a schematic flow chart of a workflow of a lighting system according to one embodiment of the present disclosure.

Description of the embodiments

The features of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings. However, it will be appreciated that the invention can be practiced in a variety of other ways than those described herein, and that those skilled in the art will be able to make similar generalizations without departing from the spirit of the invention, and therefore the invention is not limited to the specific embodiments disclosed below.

The expression "and/or" as used herein is meant to include at least one of the components listed before and after the expression. The singular forms herein also include the plural unless specifically mentioned in the language. Moreover, as used herein, the meaning of components, steps, operations, and elements that are referred to as "comprising" or "including" is that there is or is added at least one other component, step, operation, and element.

FIG. 1 is a schematic diagram of an illumination system 100 (hereinafter referred to as "illumination system 100") for a mask alignment lithographic apparatus according to one embodiment of the invention. As shown in fig. 1, illumination system 100 may include a light source module 101, a condenser module 102, a stop adjustment module, a light homogenizing module 104, a telecentric optical system 105, an electronic control system 109, and a master control system 110. In the example of fig. 1, the light source module 101, the condenser module 102, the stop adjustment module 103, the light equalizing module 104, and the telecentric optical system 105 may be placed in the lamp room 120 (dashed line box in fig. 1). The light source module 101 is used for providing illumination required by lithography, light emitted by the light source module is condensed by the light condensing module 102 and then passes through the diaphragm adjusting module, and then is guided to the mask plate 106 by the telecentric optical system 105 and irradiates on the wafer 107 after being uniformly light by the light homogenizing module 104, so that exposure of the wafer 107 is realized. The electronic control system 109 is used to provide power to the various modules of the lighting system 100, while the master control system 110 is used to control the various operations of the various modules in performing the lighting process.

The light source module 101 may be a monochromatic light or a mixed light LED light source, wherein the mixed light includes at least two spectrums. According to one embodiment of the present disclosure, the light source module 101 is implemented as an Ultraviolet (UV) spectrum LED light bead, i.e., a UV-LED. Depending on the spectral requirements of the illumination system 100, the lamp beads may contain one or more wavelength-type dies therein, all of which are integrally packaged within the same lamp bead, as shown in fig. 2. In one example, the dies 202 inside the lamp beads 201 all need to be axisymmetric or centrosymmetric.

According to an example of the present disclosure, each wavelength in the light source module 101 may employ one or more dies according to the requirement of illumination intensity, and illuminance of the mask surface may be effectively improved by increasing the number of dies. Each wavelength needs to be controlled independently, and for this purpose, an independent electrical control system can be used between the wavelengths. Fig. 3 is an electronically controlled schematic diagram for controlling a die according to one embodiment of the present disclosure. For convenience of description, the grains corresponding to three wavelengths, each having 4 grains, are only schematically shown in fig. 3. It is understood that the light source module 101 may include more or less wavelengths, each wavelength may also include a greater or lesser number of dies, and the number of dies of different wavelengths need not be equal. As shown in fig. 3, the electronic control system 9 may include a plurality of independent sub-electronic control systems (electronic control 1091, electronic control 1092, electronic control 1093). The grains with the same wavelength are connected in parallel, so that if one grain fails, only the illuminance of the emergent light is affected, but the emergent light still contains the spectrum, and the emergent spectrum of the whole lighting system is not affected.

In one example, the host system 110 may monitor the operating state of the die. For example, the current contribution of each die at each wavelength can be estimated based on the number of dies at each wavelength and the sum of die currents at that wavelength during normal operation. During operation of the light source 101, real-time changes in current are monitored. Based on the magnitude of the current change and the current contribution of the individual die, the number of failed dies can be inferred. For example, if the current suddenly changes by a value of the grain current contribution, it can be inferred that one grain is malfunctioning. Similarly, if the current surge is a multiple of the current contribution of one die, it can be inferred from the multiple how many dies failed. As compensation, the main control system 110 correspondingly adjusts the working parameters of the light source module (101), for example, the electric control system 109 can be controlled to increase the current of the crystal grain with the corresponding wavelength to increase the optical power of the remaining crystal grains, so as to ensure that the illuminance value of the emergent light with the wavelength is unchanged. In addition, the main control system 110 can also determine how much light power the remaining dies can provide according to the number of die faults, whether the light source needs to be replaced, and how much the upper current limit for the remaining dies can be set, so as to avoid burning the remaining dies by excessive current.

The diaphragm adjustment module may further comprise a diaphragm disc 103 and a rotary motor 108 controlling the rotation of the diaphragm disc 103. As shown in fig. 1, the diaphragm disk 103 may be placed between the condenser module 102 and the light equalizing module 104, and placed at the aperture stop position of the telecentric optical system 105. The diaphragm plate 103 can be manufactured into various aperture types according to the process requirements. Fig. 4 is a schematic diagram of a diaphragm disc layout according to one embodiment of the present disclosure. As shown in fig. 4, the diaphragm disk 103 may include a plurality of different types of apertures to accommodate different process requirements. For example, in the embodiment of fig. 4, three circular apertures 1031, 1032, 1033 of different sizes, a circular aperture 1034, a four-hole angular spectrum aperture 1035, a seven Kong Jiaopu aperture 1036, a positive four-trapezoid Kong Jiaopu aperture 1037, and a diagonal four-trapezoid angular spectrum aperture 1038 may be included in the diaphragm disk 103. It will be appreciated that the pore size types shown in fig. 4 are merely examples, and that many more pore size types may be formulated according to specific process requirements. In this example, circular apertures 1031-1033 are used to limit the size of the aperture stop, thereby achieving the purpose of compressing the divergence angle of the illumination exit light. The smaller the aperture, the smaller the divergence angle of the illumination exit light, but at the same time, the smaller the illuminance value of the mask face. Other types of apertures 1034-1038 are mainly used for controlling the angular spectrum distribution of the light field on the mask plate through the spatial distribution of the transmitted light, so that diffraction is effectively compressed, and resolution is improved. The rotary motor 108 may be powered by the electronic control system 109 and drives the aperture disk 103 to rotate about a central axis of rotation to different aperture positions to align the desired aperture with the light balancing module 104.

According to one embodiment of the present disclosure, the light homogenizing module 104 may be a microlens array configured to achieve light field homogenization. In one example, the microlens array is composed of an array of distributed lenses on an optical plate, with the microlenses behind the plate being at the focal points of the microlenses in front of the plate. The telecentric optical system 105 is used for ensuring that the chief ray of the light emitted from the light equalizing module 104 vertically irradiates on the mask plate 106 to form telecentric illumination, so that even if the position of the mask plate 106 translates along the direction of the emergent optical axis, the chief ray is still ensured to be perpendicular to the mask plate surface without affecting the resolution of the system.

According to a further embodiment of the present disclosure, the lighting system 100 may further comprise a heat dissipation module 113 and a temperature sensor 114. The heat dissipation module 113 may be a fan, a heat pipe, a liquid cooling or any other suitable heat dissipation form for dissipating heat from the light source module 101. The temperature sensor 114 may be mounted on a mounting board of the UV-LED lamp beads and configured to monitor the temperature at the light source module 101 in real time, preventing the temperature from being excessively high. In one example, the temperature sensor 114 communicates the monitored temperature to the master control system 110. The master control system 100 may take corresponding temperature control measures based on the monitored temperature. For example, the main control system 110 can appropriately adjust the power of the heat dissipation module 113 according to the monitored temperature value, so as to increase the heat dissipation capability. If the temperature of the light source module 101 continuously increases and exceeds the heat dissipation capacity of the heat dissipation module 113, the main control system 110 may send an alarm signal when the temperature reaches the pre-alarm value of the bearing temperature of the light source module 101. If the temperature continues to rise, and reaches the limit temperature bearing value of the light source module 101, the main control system 110 may issue a command to the electronic control system 109 to perform power-off protection on the light source module 101.

According to a further embodiment of the present disclosure, the lighting system 100 may further comprise an illuminance detection module. In one example, the illuminance detection module may include a first illuminance sensor 111 disposed inside the lamp chamber 120. In one example, the first illuminance sensor 111 is located at the light exit of the overall illumination light path, for example, may be disposed at the light exit of the lamp house 120 near the edge of the light path so as not to affect the chief ray illumination of the exiting light. The first illuminance sensor 111 may be configured to monitor the light intensity of the outgoing light in real time. However, precise control, particularly in a radiation dose control mode such as that described later, is required based on the illuminance at which the surface of the mask is actually irradiated. However, since the first illuminance sensor 111 is installed in the light box 120, the measured illuminance is not completely consistent with the illuminance of the light on the surface of the mask, and therefore, the first illuminance sensor 111 needs to be calibrated so that the reading can directly represent the actual illuminance on the surface of the mask.

To this end, according to one embodiment of the present disclosure, the illuminance detection module may further include a second illuminance sensor 112 disposed on the surface of the mask 106, for detecting illuminance at the mask 106, and by taking this as a reference, adjust the sensitivity of the first illuminance sensor 111 to different wavelengths so that the illuminance readings thereof are consistent with the readings of the second illuminance sensor 112, thereby completing the calibration of the first illuminance sensor 111.

As an example, when calibration is performed, the electronic control system 109 may be controlled by the main control system 110 such that only one wavelength of the dies in the light source module 101 is operating to emit light. At this time, the detection result of the second illuminance sensor 112 is read and input to the main control system 110. If the illuminance sensor 112 is connected to the master control system via a data line and communicates with the master control system, the detection result of the second illuminance sensor 112 is automatically input to the master control system 110. If the second illuminance sensor 112 cannot be connected to the master control system 110, the detection result of the second illuminance sensor 112 may be manually read and input to the master control system 110. The main control system 110 can automatically calculate and adjust the sensitivity of the first illuminance sensor 111 at the wavelength according to the input detection result of the second illuminance sensor 112. In other words, by setting different sensitivities for the first illuminance sensor 111 and the second illuminance sensor 112, illuminance readings of the first illuminance sensor 111 for the same wavelength light are consistent, so that the illuminance of the mask surface can be accurately represented by the readings of the first illuminance sensor 111 during photolithography. The above operation is repeated and the data of the adjusted sensitivity values of the first illuminance sensor 111 to other wavelengths are recorded. In view of the wide wavelength range, it is impossible to correct for continuous wavelengths, so some wavelength sensitivities may be discretely corrected. For example, the calibration of the first illuminance sensor 111 may be performed every 1 nm for the operating wavelength region, or other calibration steps may be set according to the specific use case, and finally completed.

After calibration, the detection result of the first illuminance sensor 111 is the same as the detection result of the second illuminance sensor 112. In other words, although the first illuminance sensor 111 is not placed on the mask plate 106, the detection result thereof coincides with the detection result on the mask plate 106. The first illuminance sensor 111 and the second illuminance sensor 112 can both perform illuminance detection on ultraviolet light in a wide spectrum, and have different sensitivities to ultraviolet light with different wavelengths, and the two illuminance sensors can independently detect a certain spectrum or detect a mixed spectrum. In normal operation, the second illuminance sensor 112 is not required, and the second illuminance sensor 112 is used only in the calibration of the first illuminance sensor 111 or in the constant current operation mode.

The value of the calibrated sensitivity is stored within the master control system 110. In any mode, the illuminance sensor may only have one sensitivity to characterize the illuminance value of the outgoing light. In the mixed wavelength operation mode, the illuminance value at a certain wavelength cannot be directly selected as a measurement reference. When the lighting system works, the main control system 110 can automatically calculate the optical power of the equivalent wavelength according to the power ratio of various wavelengths set by an operator, and then find the same value or a similar value with the wavelength from the stored value of the sensitivity, so as to select the sensitivity corresponding to the wavelength as a measurement reference, and adjust the first illuminance sensor 111 to detect the illuminance of the outgoing light, thereby improving the accuracy of illuminance value detection.

As described above, the UV-LED lighting system of the present invention can provide a mixed wavelength operation mode by integrating a plurality of dies with different wavelengths in a light source, and can conveniently realize lighting output in multiple fusion states by independent electric control of the dies with different wavelengths, and can also independently turn off the die power supply with one or more wavelengths to facilitate node and heat dissipation.

As a non-limiting example, the UV-LED lighting system of the present invention may provide at least the following modes of operation:

(1) Constant current mode

In the constant current mode, the main control system 110 can set the current value of each wavelength module die, and maintain the current value through the electronic control system 109. In one example, the upper limit of the current value may be the current value corresponding to the maximum power of all dies of such wavelength, and the lower limit of the current value may be the current value corresponding to the minimum power of all dies of such wavelength, when the current value is less than this value, the dies cannot be excited, and such wavelength cannot be lighted. In the constant current operation mode, when a certain illuminance value is required to be reached on the mask 106, the illuminance feedback needs to be performed by using the second illuminance sensor 112. The operating current at each wavelength is adjusted based on the real-time detection result of the second illuminance sensor 112 to achieve the desired output power of the illumination system 100.

(2) Constant illuminance mode

The precondition for the constant illuminance operation mode is that the calibration of the first illuminance sensor 111 has been completed. In the constant illumination mode, a desired illumination value is set by the master control system 110. The main control system 110 then controls the electronic control system 109 to automatically set the current value of the light source, and under the current operation, the input illuminance value of the lighting system reaches the preset illuminance value. When the light source module 101 is turned on, the first illuminance sensor 111 monitors the illuminance value on the mask surface 106 in real time, and feeds back the detected result to the main control system 110. The main control system 110 compares the detected result of the first illuminance sensor 111 with a preset illuminance value, calculates the deviation amount thereof, and converts the illuminance deviation amount into an electric current amount to be transmitted to the electric control system 109. The electronic control system 109 controls the power of the light source module 101 again, so as to ensure that the illuminance value on the mask plate 106 is constant at the preset value of the main control system 110.

(3) Constant dose mode

The precondition for using the constant dose mode of operation is also that the calibration of the first illuminance sensor 111 is completed. The desired dose value, as well as the desired illumination value, is set by the master control system 110. The master control system 110 then automatically calculates the operating time of the light source module 101. The calculated operating time is provided to the electronic control system 109 to control the switching of the light source module 101. After the light source module 101 is turned on, the first illuminance sensor 111 detects the illuminance value of the mask surface 106 in real time, and feeds back the detected result to the main control system 110. The main control system 110 can control the power of the emergent light by adjusting the input of the current in real time through the electric control system 109 according to the feedback detection result. Meanwhile, the master control system 110 may further calculate the dose received by the mask 106 according to the feedback illuminance value detection result of the first illuminance sensor 111 and the time integral. When the dose reaches the preset exposure dose, the main control system 110 controls the electric control system 109 to power off the light source module 101.

(4) Time-sharing exposure mode

In the time-sharing exposure mode, the total exposure dose is decomposed into different parts in one lithography process flow, and the time-sharing exposure interval is set. Subsequently, by detecting the illuminance of the inside, when the dose of the first dose reaches the preset value, the light source module 101 is powered off. When the power-off time of the light source module 101 reaches a preset interval, the light source module 101 starts to be automatically powered on, and the next exposure is started. The above steps are repeatedly performed until the set exposure dose is completed. The time-sharing exposure is adopted, so that the thermal deformation caused by temperature accumulation due to heat accumulation caused by long-time exposure can be effectively reduced.

(5) Wavelength division exposure mode

In the divided wavelength exposure mode, the order of exposure wavelengths can be set in one photolithography process flow, respectively. For example, each wavelength may be set to be sequentially exposed, or to be exposed first to some and then to some other, or to be exposed first to one of the wavelengths and then to some other, and so on, and a combination of multiple exposure wavelengths may be realized as needed. In the case of the exposure at the divided wavelengths, the exposure time, exposure dose, and the like at each wavelength can be set to control the end of the exposure. The different layers of the photoresist can be illuminated by different wavelengths through the exposure of the separated wavelengths, so that the process diversity is remarkably improved.

In addition, the divergence angle and diffraction pattern of the outgoing light can be controlled by controlling the clear aperture and angular spectrum by rotation control of the diaphragm disc 103, for example, as described above in connection with fig. 4, whether in the constant current mode, the constant illuminance mode, the constant dose mode, the time-division exposure mode, the wavelength-division exposure mode, or other modes. For example, in time-division exposure and wavelength-division exposure, different clear aperture and angular spectrum types can be set in each segment, thereby further improving the process adaptability of the illumination system.

Fig. 5 is a schematic flow chart of a workflow of a lighting system according to one embodiment of the present disclosure. The lighting system may be the lighting system 100 described in connection with fig. 1-4. As shown in fig. 5, the process begins at step 502 with the lighting system powering up.

At step 504, the interior illuminance sensor is calibrated. For example, as previously described, the sensitivity of the first illuminance sensor 111 inside the light box may be calibrated by a second external illuminance sensor 112 disposed outside the light box at the surface of the mask 106.

At step 506, the operating mode of the lighting system and associated parameter settings are determined. For example, the host system 110 may receive instructions from a user as to what mode of operation to use. As previously described, the modes of operation may include, but are not limited to: a constant current mode, a constant illuminance operation mode, a constant dose operation mode, a time-sharing exposure mode, and a wavelength-division exposure mode. For example, in the constant current mode, it is necessary to set the current at each operating wavelength; in the constant illuminance mode, an illuminance value required at the mask plate 106 needs to be set; in the constant dose mode, a dose value and an illuminance value need to be set according to a dose value required for exposure of the mask 106; setting the total dose, time-sharing times, time-sharing intervals and the like of the photoetching process in a time-sharing exposure mode; in the split wavelength exposure mode, wavelength combinations, overall dose of the lithography process, number of segments, time intervals of segments, etc. are determined.

In step 508, the clear aperture and angular spectrum pattern are determined and the diaphragm adjustment module is adjusted accordingly. For example, the master control system 110 may receive process requirements from a user and automatically set a clear aperture and an angular spectrum pattern that can meet the requirements according to the process requirements. Alternatively, the user may also directly specify the clear aperture and angular spectrum pattern. Subsequently, the main control system 110 controls the electronic control system 109 to drive the rotation motor 108 to rotate the diaphragm disk 103 to the corresponding position according to the determined clear aperture and angular spectrum pattern. It is noted that the settings of the clear aperture and angular spectrum modes are applicable to any of the illumination modes of operation mentioned above.

At step 510, after wafer 107 is completely diced and aligned, master control system 110 controls the illumination system to perform exposure according to the determined operating mode and associated parameter settings. At this time, the mask 106 is illuminated, and the photolithography process starts.

During the exposure process, the master control system 110 controls the light source module 101 to execute the operation mode selected in step 506. For example, in the constant current mode, the illuminance value of the surface of the mask plate 106 is detected by the second illuminance sensor 112, whether the illuminance value meets the requirement is determined, and then the operating current is adjusted until the illuminance value of the surface of the mask plate 106 meets the use requirement. In the constant illuminance mode, illuminance value real-time detection feedback is performed by the first illuminance sensor 111. In the constant dose mode, the illuminance value real-time detection feedback is performed by the first illuminance sensor 111, and converted into an exposed dose value by integrating over time. When the dose reaches the preset exposure dose, the main control system 110 controls the electric control system 109 to power off the light source module 101.

In the time-division exposure mode, the start and end of each minute period are determined by the first illuminance sensor 111 as feedback of the dose detection result for each minute period. For example, when the exposure is performed, the first illuminance sensor 111 may detect the dose at this time, and after reaching the set value, the light source 101 is controlled to be powered off. When the power-off time reaches a preset interval between the time segments, the power-on is automatically conducted to expose the next time segment. And sequentially completing the exposure of each time period according to the process. Time-shared exposure prevents the one-time exposure from being too long to trigger a thermal response.

In the sub-wavelength exposure mode, a combination of wavelengths in the sub-wavelength exposure mode, an overall dose of the lithographic process, a number of segments, and a time interval of segments are determined. The start and end of each minute period are determined by the first illuminance sensor 111 as feedback of the dose detection result for each minute period for each wavelength. In this process, the split-wavelength exposure may also be fused with a time-shared exposure, i.e. a further time-shared exposure may be performed for different wavelengths.

In addition, the temperature sensor 114 feeds back the temperature detection result to the main control system 110 in real time during the exposure. Based on the temperature detection result, the main control system 110 determines whether to increase the heat dissipation power of the heat dissipation module 113. If the temperature is too high to give an alarm, if the temperature exceeds the upper limit of the use of the light source module 101, the electronic control system 109 is instructed to perform power-off protection on the light source module 101.

Finally, at step 512, after the exposure is completed, the master control system 110 may control the lighting system to perform shutdown. For example, the individual components of the lighting system may be sequenced in accordance with a set shutdown procedure until the entire lighting system is shut down.

What has been described above includes examples of aspects of the claimed subject matter. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Accordingly, the disclosed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims.

Claims

1. An illumination system (100) for a mask alignment lithographic apparatus, comprising:

a light source module (101) for providing illumination required for lithography;

a light condensing module (102) for condensing light emitted from the light source module (101);

the diaphragm adjusting module is used for providing clear aperture and angular spectrum required in the photoetching task;

a light equalizing module (104) for equalizing the light passing through the diaphragm adjusting module;

a telecentric optical system (105) for guiding the homogenized light to a mask plate;

-an electronic control system (109) for providing power to the individual modules of the lighting system (100); and

a master control system (110) for controlling the individual modules of the lighting system (100) to perform operations during lighting,

wherein the light source module (101) comprises a UV-LED lamp bead in which are packaged one or more wavelength-type dies, each wavelength-type die comprising one or more dies connected in parallel with each other, and each wavelength-type die being independently controlled by the electronic control system (109),

the lighting system (100) further comprises an illuminance detection module, the illuminance detection module further comprising:

a first illuminance sensor (111) for detecting illuminance of light emitted from the telecentric optical system (105); and

a second illuminance sensor (112) for detecting illuminance of light at the surface of the mask plate (106), and

the master control system (110) is further configured to perform a sensitivity calibration procedure for the first illuminance sensor (111), the sensitivity calibration procedure comprising:

the main control system (110) controls the electric control system (109) to enable only one wavelength of crystal grains in the light source module (101) to work and emit light;

reading an illuminance detection result of the second illuminance sensor (112);

the main control system (110) calculates and adjusts the sensitivity of the first illuminance sensor (111) under the wavelength according to the detection result of the second illuminance sensor (112) so that the reading of the first illuminance sensor (111) is consistent with the reading of the second illuminance sensor (112);

repeating the above steps with a preset wavelength step in an operating wavelength region of the light source module (101); and

the calibrated sensitivity value is stored in the master control system (110).

2. The lighting system (100) of claim 1, wherein the diaphragm adjustment module further comprises:

a diaphragm disc (103), on which a clear aperture and an angular spectrum filter of various sizes are provided and which is rotatable about a central rotation axis; and

a rotating motor (108) for driving the diaphragm disc (103) to rotate about the central rotation axis to different aperture positions.

3. The lighting system (100) of claim 1, wherein the master control system (110) is configured to control the respective modules of the lighting system (100) to perform any one of the following lighting modes of operation, the lighting modes of operation comprising: a constant current mode, a constant illuminance operation mode, a constant dose operation mode, a time-sharing exposure mode, and a wavelength-division exposure mode.

4. A lighting system (100) as claimed in claim 3, wherein the master control system (110) is further configured to:

for the radiation illuminance values of different wavelengths, according to the proportion of the radiation illuminance values of the set wavelengths, the equivalent wavelength of the mixed wavelength is automatically calculated;

searching a sensitivity value corresponding to the wavelength which is the same as or similar to the equivalent wavelength in the stored sensitivity data of the illuminance sensor; and

the first illuminance sensor (111) is set according to the sensitivity value, and the outgoing illuminance detection is performed.

5. The lighting system (100) of claim 1, wherein the master control system (110) is further configured to:

monitoring an operating state of a die in the light source module (101), comprising:

estimating the current contribution of each crystal grain of each wavelength according to the number of crystal grains of each wavelength and the sum of the crystal grain currents of the wavelength in normal operation;

during operation, monitoring the current variation; and

inferring the number of failed dies based on the magnitude of the current change and the current contribution of the individual dies; and

based on the inferred number of failed dies, operating parameters of the light source module (101) are adjusted.

6. The lighting system (100) of claim 1, further comprising:

a heat radiation module (113) for radiating heat from the light source module (101); and

a temperature sensor (114) for monitoring the temperature of the light source module (101) and reporting to the master control system (110), and

the master control system (110) is further configured to perform corresponding temperature control measures in dependence of the temperature reported by the temperature sensor (114).

7. A mask alignment lithographic apparatus comprising an illumination system (100) according to any of claims 1-6.

8. A lighting method implemented by the lighting system (100) of any one of claims 1-6, the lighting method comprising:

calibrating a first illuminance sensor of the illumination system (100);

determining an operating mode of the lighting system (100) and related parameter settings;

determining a clear aperture and an angular spectrum mode, and correspondingly adjusting the diaphragm adjusting module; and

the exposure is performed according to the determined operation mode and the related parameter settings.