CN111856891A - Temperature Compensation Device for Optimizing the Thermal Effect of Workpiece Stage in Lithography Equipment - Google Patents

Abstract

The invention discloses a temperature compensation device for optimizing the thermal effect of a workpiece stage in a lithography equipment, comprising: a heating lamp tube group arranged in the workpiece stage and located under a silicon wafer fixing mechanism, the heating lamp tube group comprising a plurality of parallel arranged A heating lamp tube, wherein a plurality of heating lamps arranged along its axial direction are arranged in the heating lamp tube; wherein, by detecting the temperature of a local area on the silicon wafer fixing mechanism above each of the heating lamps, and When it exceeds a threshold range, by adjusting the power of the heating lamp under the corresponding area, the brightness of the heating lamp changes, so as to control the temperature of the area to be consistent with the threshold, so as to ensure that the entire silicon wafer fixing mechanism and its upper Temperature uniformity of placed wafers. The invention can reduce the influence of the thermal effect of the lithography equipment, and can effectively control the overetching precision in the whole silicon wafer area, thereby increasing the yield of the silicon wafer.

Description

Temperature Compensation Device for Optimizing the Thermal Effect of Workpiece Stage in Lithography Equipment

technical field

The invention relates to the technical field of integrated circuit manufacturing and lithography equipment, in particular to a temperature compensation device for optimizing the thermal effect of a workpiece stage in a lithography equipment.

Background technique

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of the heating and cooling states of a silicon wafer during EUV lithography. As shown in FIG. 1 , in, for example, 13.5 nm EUV lithography, a silicon wafer 11 is placed on a workpiece stage of an EUV lithography apparatus for exposure. A silicon wafer fixing mechanism 10 is arranged on the workpiece table, and a water cooling mechanism 12 is arranged inside the workpiece table below the silicon wafer fixing mechanism 10 for cooling. During the exposure process, due to the complex work and relative vacuum environment, the heat of the silicon wafer 11 increases continuously, mainly due to the absorption of short-wave extreme ultraviolet light, long-wave infrared light, and of course the dynamic gas lock in the exposure process. released power.

The main sources of heat loads currently present in EUV systems include:

(1) The extreme ultraviolet light is all absorbed by the photoresist covered on the silicon wafer, and the energy is converted into a heat source.

(2) Infrared rays follow the process characteristics of silicon wafers and can be absorbed, reflected and transmitted.

(3) Part of the load of the dynamic gas lock will be absorbed by the silicon wafer.

The heating of the silicon wafer 11 will cause mechanical deformation of the silicon wafer 11 and the silicon wafer fixing mechanism (eg, electrostatic chuck) 10, and due to the above deformation, the pattern on the reticle will be exposed to an offset position, which will lead to overprinting. and focusing error.

The hardware design of the silicon wafer fixing mechanism 10 is to keep the temperature of the silicon wafer 11 and the silicon wafer fixing mechanism 12 as stable as possible, but in the current equipment structure, the cooling effect brought by the water cooling mechanism 12 cannot completely prevent the The deformation problem of the wafer 11 and the silicon wafer fixing mechanism 10 .

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and to provide a temperature compensation device that optimizes the thermal effect of the workpiece stage in the lithography equipment, so as to achieve uniform heating of the silicon wafer and reduce uneven cooling of the silicon wafer fixing mechanism. .

For achieving the above object, technical scheme of the present invention is as follows:

A temperature compensation device for optimizing the thermal effect of a workpiece table in a lithography apparatus, comprising: a heating lamp tube group arranged in the workpiece table and below a silicon wafer fixing mechanism, the heating lamp tube group comprising a plurality of heating lamps arranged in parallel, The heating lamp tube is provided with a plurality of heating lamps arranged along its axial direction; wherein, the temperature of the local area on the silicon wafer fixing mechanism above each of the heating lamps is detected, and when the temperature exceeds a threshold value In the range, by adjusting the power of the heating lamp under the corresponding area, the brightness of the heating lamp changes, so as to control the temperature of the area to be consistent with the threshold, so as to ensure that the entire silicon wafer fixing mechanism and the silicon wafers placed on it are temperature uniformity.

Further, each of the heating lamps is individually connected with a temperature sensing element, and forms a closed-loop control, and the temperature sensing element is connected with an information storage and processing module through an information transmission module, and the information storage and processing module is directed to the The temperature data transmitted by the temperature sensing element, after data analysis and comparison with the threshold value, instructs a heating control circuit to automatically adjust the power supply current of the heating lamp to adjust the power of the heating lamp to make its brightness occur. Strength changes.

Further, the information storage and processing module is provided with a storage unit and a processing unit, the storage unit is used to store the temperature data sensed by the temperature sensing element, and the processing unit is used to analyze and analyze the temperature data. Compared with the threshold value, and sending a command to the heating control circuit.

Further, the information storage and processing module is connected to an analysis module, and the analysis module is used for real-time analysis of the temperature change trend on the silicon wafer and the silicon wafer fixing mechanism, so as to be further used for analyzing the optical properties of the silicon wafer. effect on engraving accuracy.

Further, the heating lamps are arranged in a direction corresponding to the column direction of the silicon wafers.

Further, each of the heating lamps is uniformly or non-uniformly arranged along the axial direction of the heating lamp tube.

Further, according to the diameter of the silicon wafer, the length range of the heating lamps and the corresponding arrangement of the heating lamps are adjusted.

Further, the heating lamps include LED lamps.

Further, the temperature sensing element includes a temperature sensor, the storage unit includes a memory, the processing unit includes a central processing unit, and the heating control circuit includes a heating driver.

Further, the central processing unit transmits a signal to the heating driver to automatically adjust the heating power supply current, so that the power of the heating lamp decreases, and the brightness thereof decreases, and is used in conjunction with the water cooling tube to adjust the temperature of the corresponding area.

It can be seen from the above technical solutions that the present invention can perform temperature detection and fine-tuning on the partitions of the silicon wafer and the silicon wafer fixing mechanism by arranging a heating lamp tube (group) with a closed-loop temperature control under the silicon wafer fixing mechanism, and can pass The external software (analysis module) monitors the temperature change trend of key positions on the silicon wafer in real-time row by column, thus reducing the uneven temperature on the silicon wafer and the fixing mechanism of the silicon wafer, and further reducing the thermal effect of the lithography equipment. influence, and can effectively control the overlay accuracy within the entire silicon wafer area, thereby increasing the yield of silicon wafers.

Description of drawings

FIG. 1 is a schematic diagram of the heating and cooling states of a silicon wafer during EUV lithography.

2 is a schematic structural diagram of a temperature compensation device for optimizing the thermal effect of a workpiece stage in a lithography apparatus according to a preferred embodiment of the present invention.

FIG. 3 is an enlarged schematic view of the structure of part A in FIG. 2 .

FIG. 4 is an exploded schematic view of the arrangement structure of a heating lamp tube on the workpiece table according to a preferred embodiment of the present invention.

5 is a schematic diagram of the relative arrangement between a heating lamp tube and a silicon wafer according to a preferred embodiment of the present invention.

6 is a schematic diagram of a power adjustment principle of an LED lamp according to a preferred embodiment of the present invention.

FIG. 7 is a schematic block diagram of a temperature compensation according to a preferred embodiment of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

It should be noted that, in the following specific embodiments, when describing the embodiments of the present invention in detail, in order to clearly represent the structure of the present invention and facilitate the description, the structures in the accompanying drawings are not drawn according to the general scale, and the Partial enlargement, deformation and simplification of processing are shown, therefore, it should be avoided to interpret this as a limitation of the present invention.

In the following specific embodiments of the present invention, please refer to FIGS. 2 and 3 , FIG. 2 is a schematic structural diagram of a temperature compensation device for optimizing the thermal effect of the workpiece stage in a lithography apparatus according to a preferred embodiment of the present invention, and FIG. 3 is a The enlarged schematic diagram of the structure of part A in 2. As shown in FIG. 2 and FIG. 3 , a temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus of the present invention is arranged on the workpiece stage 20 in the lithography apparatus, and a silicon wafer is provided on the upper surface of the workpiece stage 20 Fixing mechanism 24 . The silicon wafer fixing mechanism 24 can be, for example, an electrostatic chuck 24 made of silicon carbide material, but is not limited thereto. The electrostatic chuck 24 is used to adsorb the silicon wafer 22 on its surface for processing; a plurality of bumps 23 can be evenly arranged on the electrostatic chuck 24 , and the silicon wafer 22 is placed on the bumps 23 of the electrostatic chuck 24 . The bumps 23 are arranged on the electrostatic chuck 24 to prevent the problem of contamination of the silicon wafer 22 from occurring.

Please refer to Figure 2 and Figure 4. A heating lamp tube group is provided inside the workpiece table 20 below the electrostatic chuck 24 ; the heating lamp tube group includes a plurality of parallel and horizontally arranged heating lamps 21 . Wherein, each heating lamp tube 21 is provided with a plurality of heating lamps 28 (refer to FIG. 4 ); the heating lamps 28 are evenly arranged along the axial direction of the heating lamp tube 21; In the area where the temperature unevenness occurs, make the uneven setting in the corresponding area. The heating lamp 28 can be, for example, an LED lamp 28, then the heating lamp 21 becomes an LED lamp 21, and the LED lamps 21 are arranged in parallel under the electrostatic chuck 24 to form an LED lamp group. But not limited to this.

Please refer to Figure 5. As a preferred embodiment, the LED lamps 21 can be arranged in a direction corresponding to the arrangement direction of the array of chips on the silicon wafer 22 . For example, the chamfer 27 used for identification on the silicon wafer 22 in the figure is now located below, that is, the arrangement direction of the array of chips on the silicon wafer 22 is the vertical direction, then the LED lamps 21 are also arranged in the vertical direction. and settings.

As an optional implementation, taking a 300mm silicon wafer 22 as an example, 10 to 22 rows of LED lamps 21 can be arranged, such as the 10 rows of LED lamps 21 shown in the figure; and 3 rows of LED lamps 21 can be arranged in each row Up to 20 uniformly arranged temperature-controlled LED lamps 28, for example, the LED lamps 21 located in row 5 in the figure are provided with row 1 to row 8 LED lamps 28. The length of the LED lamp 21 may be about 50 to 450 mm; the length of the LED lamp 21 and the corresponding arrangement of the LED lamps 28 can be adjusted according to the diameter of the silicon wafer. The length occupied by each LED light 28 in the LED light tube 21 may be about 10 mm, and the diameter of the LED light tube 21 may be about 5 to 10 mm.

Please refer to Figure 2 and Figure 3. Each LED light 28 in each LED light tube 21 is individually connected with a temperature sensing element 25 to form a closed-loop control, and data transmission and feedback are performed through the information storage and processing module. As the temperature sensing element 25, a temperature sensor 25 can be used, for example. The temperature sensor 25 can be installed between the silicon wafer 22 and the electrostatic chuck 24 , in the space between the bumps 23 , and above the corresponding LED lamp 28 . At the same time, a water cooling pipe 26 of a water cooling mechanism is also provided in the gap between the bumps 23 having the temperature sensor 25 .

Please refer to Figure 6. A serial number (eg, a plane coordinate position) can be set for each temperature sensor 25 individually connected to each LED lamp 28 , such as serial numbers 5,1 to 5,8 shown in the figure.

In this way, the temperature of the corresponding local area on the electrostatic chuck 24 above each LED lamp 28 can be detected by using the provided temperature sensor 25 . When the detected temperature exceeds a threshold range, the power of the LED lights 28 under the corresponding area can be adjusted, for example, the power values (W) of 65, 55, 70, 65, 45, 55, 60, and 43 shown in FIG. 6 , so that the brightness of the corresponding LED lamp 28 changes in intensity to control the temperature of the region to be consistent with the threshold value, thereby ensuring the temperature uniformity of the entire electrostatic chuck 24 and the silicon wafer 22 placed thereon.

Please refer to Figure 7. The temperature sensor 25 can be connected with the information storage and processing module through the information transmission module. The information storage and processing module may be provided with a storage unit and a processing unit, the storage unit may be, for example, a conventional memory, and the processing unit may be, for example, a central processing unit. The memory can be used to store the temperature data sensed by the temperature sensor 25, and the central processing unit can be used to analyze and compare the temperature data (including the serial number containing the row number and the column number) transmitted by the temperature sensor 25 with the threshold value, and report it to the heating control. The circuit sends the command. The heating control circuit may be provided with an LED driver (heating driver) for automatically adjusting the LED power supply current, so as to adjust the power of the LED lamp 28 to change its brightness.

For example, assuming that the threshold range is 22.5±0.01 degrees Celsius, when the temperature on the silicon wafer 22 at the position of one of the LED lights 28 is higher than 22.5 degrees Celsius, the temperature difference information can be transmitted to the memory, and after data analysis and comparison, the central processing unit The signal is transmitted to the LED driver, which can automatically adjust the LED power supply current, so that the power of the LED lamp 28 will decrease, and then its brightness will decrease. It is used in conjunction with the water cooling tube 26 to adjust the temperature, thereby ensuring the uniformity of temperature control in this area. Ensure that the temperature in this area is within the control accuracy of 22.5 ± 0.01 degrees Celsius.

Further, the central processing unit can also be connected to an analysis module, and the analysis module can be, for example, external analysis software. Using the software, the temperature change trend on the silicon wafer 22 and the electrostatic chuck 24 can be analyzed in real time, and the influence of the temperature change trend on the lithography accuracy of the silicon wafer 22 can be further analyzed.

The present invention can be applied to extreme ultraviolet lithography. A temperature-controlled LED lamp tube group is arranged under the electrostatic chuck 24, and the arrangement and control method of the LED lamp tubes 21 can further improve the performance of the workpiece table 20 in the existing water cooling and temperature control. The uniformity of the heating under the condition of the temperature can reduce the influence of the flow change of the water cooling tube 26 or the abnormality of the water temperature sensor on the exposure, reduce the uneven temperature of the silicon wafer 22 and the electrostatic chuck 24, and further reduce the heat effect of the EUV lithography equipment. Therefore, it is possible to increase the yield of silicon wafers, especially to reduce the overlay deviation within and between exposure areas.

Replacing the parts of the LED lamp tube 21 usually takes about 1 to 2 hours each time, and can be completed together with other cavity opening maintenance work.

The above are only the preferred embodiments of the present invention, and the embodiments are not intended to limit the protection scope of the present invention. Therefore, any equivalent structural changes made by using the contents of the description and drawings of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. A temperature compensation device for optimizing the thermal effect of a workpiece table in a lithography apparatus, characterized in that it comprises: a heating lamp tube group arranged in the workpiece table and positioned below the silicon wafer fixing mechanism, the heating lamp tube group comprising a plurality of parallel A heating lamp tube is provided, wherein a plurality of heating lamps arranged along its axial direction are arranged in the heating lamp tube; wherein, the temperature of a local area on the silicon wafer fixing mechanism above each of the heating lamps is detected by detecting the temperature , and when it exceeds a threshold range, by adjusting the power of the heating lamp below the corresponding area, the brightness of the heating lamp changes in intensity, so as to control the temperature of the area to be consistent with the threshold. 2. The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 1, wherein each of the heating lamps is individually connected with a temperature sensing element, and forms a closed-loop control, and the temperature sensing element The information transmission module is connected to an information storage and processing module, and the information storage and processing module instructs a heating control circuit to process the temperature data from the temperature sensing element after data analysis and comparison with the threshold. The power supply current of the heating lamp is automatically adjusted to adjust the power of the heating lamp, so that the brightness of the heating lamp changes in intensity. 3. The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 2, wherein the information storage and processing module is provided with a storage unit and a processing unit, and the storage unit is used to store the The temperature data sensed by the temperature sensing element, the processing unit is configured to analyze the temperature data and compare it with the threshold value, and send an instruction to the heating control circuit. 4. The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 2, wherein the information storage and processing module is connected with an analysis module, and the analysis module is used for real-time analysis of the silicon The temperature change trend on the wafer and the silicon wafer fixing mechanism is further used to analyze the influence on the lithography accuracy of the silicon wafer. 5 . The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 1 , wherein the heating lamps are arranged in a direction corresponding to the column direction of the silicon wafers. 6 . 6 . The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 1 , wherein each of the heating lamps is uniformly or non-uniformly arranged along the axial direction of the heating lamp tube. 7 . 7 . The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 1 , wherein the length range of the heating lamps and the corresponding arrangement of the heating lamps are adjusted according to the diameter of the silicon wafer. 8 . 8 . The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 1 , wherein the heating lamp comprises an LED lamp. 9 . 9. The temperature compensation device for optimizing the thermal effect of a workpiece stage in a lithography apparatus according to claim 1, wherein the temperature sensing element comprises a temperature sensor, the storage unit comprises a memory, and the processing unit comprises a central processing unit , the heating control circuit includes a heating driver. 10. The temperature compensation device for optimizing the thermal effect of the workpiece stage in the lithography apparatus according to claim 9, wherein the central processing unit transmits a signal to the heating driver to automatically adjust the heating power supply current, so that the heating lamp The power of the device drops to make its brightness drop, and it is used in conjunction with the water cooling tube to adjust the temperature of the corresponding area.

Images