Wafer electrostatic adsorption heating device

Abstract

The present invention discloses a wafer electrostatic adsorption heating device, including a heater substrate, on which a plurality of gas channels are arranged, all of which are interconnected and connected to a gas source through a gas pipeline at the bottom of the heater substrate for wafer back blowing, wherein a plurality of mounting blind holes are processed and arranged on the heater substrate, in which a micro chuck for adsorbing and fixing the wafer is embedded, and the surface of the micro chuck after installation is lower than the surface of the heater substrate, so that the wafer directly fits the heater substrate; a mass flow meter is arranged on the gas pipeline for measuring and adjusting the gas pressure, and the number of micro chucks activated is related to the gas pressure monitored by the mass flow meter. The wafer electrostatic adsorption heating device provided by the present invention can not only increase the heat transfer efficiency, but also adjust the number of micro chucks activated according to the back blowing process gas pressure, so as to obtain a wafer with a smaller warpage.

Description

Technical Field

[0001] The invention relates to an electrostatic adsorption heating device, in particular to a wafer electrostatic adsorption heating device. Background Art

[0002] In the field of semiconductor manufacturing equipment, metal sputtering and wafer heating technology, electrostatic chucks and heaters are used to fix and heat wafers respectively to ensure that the wafers meet the process requirements during processing. With the development of technology, the types and process requirements of wafers are increasing. Electrostatic chucks cannot withstand higher temperatures. Different wafers require different back-blowing process gas pressures. It is impossible to effectively adjust the adsorption force of the electrostatic chuck to obtain a wafer with a smaller warpage. The heating time and speed are also difficult to meet higher requirements.

[0003] This is because the traditional electrostatic chuck conduction heating method requires its own conduction heating, which not only reduces the heat transfer efficiency, but also increases the complexity and cost of the equipment. In addition, when the existing technology processes wafers of different thicknesses and warpages, the electrostatic chuck adsorption force cannot be adjusted, and different electrostatic chucks need to be replaced, which not only increases the complexity of the equipment, but also may lead to a decrease in production efficiency. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a wafer electrostatic adsorption heating device, which can not only increase the heat transfer efficiency, but also adjust the number of micro chucks activated according to the back-blowing process gas pressure to obtain a wafer with smaller warpage.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is to provide a wafer electrostatic adsorption heating device, including a heater substrate, a plurality of gas channels are arranged on the heater substrate, all the gas channels are interconnected and connected to a gas source through a gas pipeline at the bottom of the heater substrate for wafer back blowing, wherein a plurality of mounting blind holes are processed and arranged on the heater substrate, a miniature chuck for adsorbing and fixing the wafer is embedded in the mounting blind hole, the surface of the miniature chuck after installation is lower than the surface of the heater substrate, so that the wafer is directly attached to the heater substrate; a mass flow meter is arranged on the gas pipeline for measuring and adjusting the gas pressure, and the number of activated miniature chucks is related to the gas pressure monitored by the mass flow meter.

[0006] Furthermore, the number of the mounting blind holes is 18, the mass flow meter measures and adjusts the gas pressure to 3 torr, 4 torr, 5 torr, 6 torr or 7 torr, and the corresponding number of enabled micro chucks is 12-18.

[0007] Furthermore, when the mass flow meter monitors the gas pressure to be 3 torr, 4 torr or 6 torr, the number of micro chucks selected to be started is 12; when the mass flow meter monitors the gas pressure to be 5 torr, the number of micro chucks selected to be started is 15; when the mass flow meter monitors the gas pressure to be 7 torr, the number of micro chucks selected to be started is 18.

[0008] Furthermore, the heater substrate is in a disc shape, and the mounting blind holes are evenly distributed along the inner and outer circles on the heater substrate, with 6 blind holes distributed on the inner circle and 12 blind holes distributed on the outer circle.

[0009] Furthermore, the heater substrate is disc-shaped, with 6 gas channels distributed at equal arcs along the radial direction, and 3 mounting blind holes distributed between two adjacent gas channels.

[0010] Furthermore, the micro chuck includes a base layer, an electrode layer and a ceramic outer layer, the ceramic outer layer and the electrode layer are connected by an adhesive layer, the electrode layer leads out positive and negative electrodes, and the positive and negative electrodes of all micro chucks are connected in parallel and bundled.

[0011] Furthermore, the shape of the mounting blind hole is circular, hexagonal or slot-shaped.

[0012] Furthermore, a first fixing threaded hole is provided at the bottom of the mounting blind hole, and a second fixing threaded hole is provided at the bottom of the micro chuck. The first fixing threaded hole and the second fixing threaded hole are aligned and the micro chuck is locked with a screw.

[0013] Furthermore, the heater substrate is made of stainless steel, the thickness of the heater substrate is 20 mm, the diameter is 310 mm, the size of the mounting blind hole is 12 mm in diameter, and the groove depth is 8 mm.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the wafer electrostatic adsorption heating device provided by the present invention fixes the wafer by machining an electrostatic chuck mounting hole on a heater substrate and embedding a micro chuck therein. This method can effectively solve the problem that the traditional electrostatic chuck needs to be heated by itself during use, thereby increasing the heat transfer efficiency. At the same time, the present invention can also adjust the number of micro chucks enabled according to the back-blowing process gas pressure, adjust the electrostatic chuck adsorption force, and obtain a wafer with a smaller warpage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1a It is a schematic diagram of the structure of the wafer electrostatic adsorption heating device of the present invention;

[0016] Figure 1b It is a schematic diagram of the cross-sectional structure of the wafer electrostatic adsorption heating device of the present invention;

[0017] Figure 2 This is a schematic diagram of the use of the wafer electrostatic adsorption heating device of the present invention;

[0018] Figure 3 It is a schematic diagram of the structure of a heater substrate with a circular mounting blind hole according to the present invention;

[0019] Figure 4 It is a schematic structural diagram of a heater substrate with a slot-shaped mounting blind hole according to the present invention;

[0020] Figure 5 It is a schematic structural diagram of a heater substrate with hexagonal mounting blind holes according to the present invention;

[0021] Figure 6 A relationship diagram between the wafer warpage and the number of micro-chuck openings of the present invention;

[0022] Figure 7 It is a schematic diagram of the structure of the micro chuck of the present invention.

[0023] The markings in the figure are:

[0024] 1. Wafer; 2. Heater substrate; 3. Mounting blind hole; 4. Micro chuck; 5. Vacuum port; 6. Heater; 7. Upper chamber; 8. DC power supply; 9. Rotating motor; 10. Magnet; 11. Target; 12. Lower chamber; 13. Hand valve; 14. Mass flow meter; 15. Gas source; 16. Substrate fixing hole; 17. First fixed threaded hole; 18. Gas channel; 19. Slot-shaped mounting blind hole; 20. Hexagonal mounting blind hole; 21. Positive and negative electrodes; 22. Base layer; 23. Electrode layer; 24. Adhesive layer; 25. Ceramic outer layer; 26. Cross screw; 27. Gas pipeline; 28. Electrode assembly cluster; 29. ​​Hexagon socket screw; 30. Second fixed threaded hole. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1a It is a schematic diagram of the structure of the wafer electrostatic adsorption heating device of the present invention; Figure 1b It is a schematic diagram of the cross-sectional structure of the wafer electrostatic adsorption heating device of the present invention.

[0027] See also Figure 1a and Figure 1bThe wafer electrostatic adsorption heating device provided by the present invention includes a heater substrate 2, on which a plurality of gas channels 18 are arranged, all of which are interconnected and connected to a gas source 15 through a gas pipeline 27 at the bottom of the heater substrate for wafer back blowing, wherein a plurality of mounting blind holes 3 are processed and arranged on the heater substrate 2, and a micro chuck 4 for adsorbing and fixing the wafer is embedded in the mounting blind holes 3, and the surface of the micro chuck 4 after installation is slightly lower than the surface of the heater substrate 2, so that the wafer 1 is directly attached to the heater substrate 2; a mass flow meter 14 is arranged on the gas pipeline 27 for measuring and adjusting the gas pressure, and the number of micro chucks 4 enabled is related to the gas pressure monitored by the mass flow meter 14.

[0028] Please continue to see Figure 2 In the wafer electrostatic adsorption heating device provided by the present invention, the wafer 1 is in the lower chamber 12 during metal sputtering, and the bottom is in contact with the heater substrate 2. The micro chuck 4 is fixed on the heater 6 by installing the blind hole 3. The upper chamber 7 has the target material 11 required for the metal sputtering process, and a rotating motor 9 and a magnet 10 are provided on it to provide the magnetic field required for the metal sputtering process. The vacuum port 5 provides a high vacuum environment for the lower chamber 12. A gas source 15 is provided at the bottom of the heater 6 for wafer back blowing. The pipeline has a mass flow meter 14 to monitor and adjust the gas pressure, and the switch is controlled by a manual valve 13.

[0029] The mounting blind hole 3 of the present invention is preferably a circular hole, and the arrangement of the mounting blind hole 3 on the heater substrate 2 is as follows: Figure 3 As shown, a substrate fixing hole 16 and a mounting blind hole 3 are processed on the heater substrate 2. The heater substrate 2 is fixed on the heater 6 by the substrate fixing hole 16 to prevent movement. The heater substrate 2 is made of 316L material with high thermal conductivity, with a thickness of 20mm and a diameter of 310mm. There are 6 gas channels 18 in the middle for wafer back blowing. The size of the mounting blind hole 3 is 12mm in diameter and 8mm in groove depth. The first fixed threaded hole 17 is processed in the middle of the bottom of the mounting blind hole 3. In order to facilitate the adaptation to micro chucks of different shapes, the shape of the mounting blind hole can also be changed to a groove-shaped mounting blind hole 19, such as Figure 4 Or hexagonal blind hole 20, such as Figure 5 As shown; other shapes of mounting blind holes can also be selected according to actual needs to match micro chucks 4 of different shapes. This design can effectively conduct heat and adapt to wafers of different thicknesses and warpages.

[0030] The micro chuck structure of the present invention is as follows Figure 6As shown, the top layer is a ceramic outer layer 25, and the lower layer is an adhesive layer 24, which is mainly bonded to the base layer 22 and the electrode layer 23. The material of the base layer 22 can be stainless steel; the entire electrode layer is connected to the DC voltage by the positive and negative electrodes 21, and the surface of the electrode layer will generate polarized charges, which will generate charges of opposite polarity on the surface of the wafer, thereby forming an electrostatic attraction to attract the wafer. After the micro chuck 4 is embedded in the heater substrate 2, the first fixed threaded hole 17 on the heater substrate is aligned with the second fixed threaded hole 30 on the micro chuck 4, and fixed with a hexagon socket screw 29, and the remaining micro chucks are installed in turn, and the heater substrate 2 with the micro chuck is installed on the heater 6 as a whole, and fixed with a cross screw 26, and the bottom gas pipeline 27 is connected to the gas source 15, and the positive and negative electrode 21 wire harness of the micro chuck is summarized and led out through the electrode summary bundle 28, and finally connected to the DC power supply 8. Each micro chuck 4 is a separate module, which is powered separately, and can be turned on and off separately by PLC control.

[0031] The present invention places the wafer 1 on the micro chuck 4, conducts heat through the substrate heater 2, and heats the wafer 1. The surface of the micro chuck 4 after installation is slightly lower than the surface of the heater substrate 2, so that the wafer 1 is directly attached to the heater substrate 2. The gas pressure of the mass flow meter 14 is adjusted to five commonly used experimental data of 3torr, 4torr, 5torr, 6torr, and 7torr, and the number of micro chuck starts and the wafer warpage measured data after the metal sputtering process are recorded in each set of experimental data. Specifically, when the mass flow meter monitors the gas pressure of 3 torr, the optimal number of micro chucks started is 12; when the mass flow meter monitors the gas pressure of 4 torr, the optimal number of micro chucks started is 12; when the mass flow meter monitors the gas pressure of 5 torr, the optimal number of micro chucks started is 15; when the mass flow meter monitors the gas pressure of 6 torr, the optimal number of micro chucks started is 12; when the mass flow meter monitors the gas pressure of 7 torr, the optimal number of micro chucks started is 18. Figure 7 Shown is the effect of the number of micro chucks used at different gas pressures on the warpage of the wafer after processing is completed.

[0032] The above is the specific implementation method of this embodiment, which can effectively improve the heat transfer efficiency of wafer heating, adjust the number of electrostatic chuck activations to reduce the warpage of the wafer after the process, simplify the operation process, and improve the adaptability and production efficiency of the equipment.

[0033] The wafer electrostatic adsorption heating device provided by the present invention has the following beneficial effects:

[0034] 1. Improve heat transfer efficiency: The present invention heats the wafer 1 by machining an electrostatic chuck mounting hole on the heater substrate 2 and embedding a micro chuck 4 therein. In this way, the heat is directly conducted by the heater substrate 2, so that a good heat conduction path can be formed between the base and the wafer 1, thereby avoiding the low efficiency problem of the traditional electrostatic chuck conduction heating method.

[0035] 2. Adapting to wafers of different thicknesses and warpages: The present invention adjusts the number of activations of the micro chuck according to the size of the back-blowing pressure, thereby achieving the minimum warpage of the wafer.

[0036] 3. Simplified operation process: The number of micro chucks can be adjusted automatically, which avoids the complexity of manual adjustment and improves the accuracy of adjustment.

[0037] 4. Reduce equipment complexity: The design of the base of the present invention with reserved grooves arranged in a matrix and micro-chucks can reduce the complexity of the equipment and reduce the manufacturing cost and maintenance cost of the equipment.

[0038] 5. Improve production efficiency: The design of the present invention makes the heating process of the wafer more efficient and reliable, thereby improving production efficiency and reducing production costs.

[0039] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A wafer electrostatic adsorption heating device, comprising a heater substrate, on which a plurality of gas channels are arranged, all of which are interconnected and connected to a gas source through a gas pipeline at the bottom of the heater substrate for wafer back blowing, characterized in that: The heater substrate is provided with a plurality of mounting blind holes, in which a micro chuck for adsorbing and fixing the wafer is embedded. The surface of the micro chuck after installation is lower than the surface of the heater substrate, so that the wafer is directly attached to the heater substrate. A mass flow meter is provided on the gas pipeline for measuring and adjusting the gas pressure, and the number of micro chucks activated is related to the gas pressure monitored by the mass flow meter.

2. The wafer electrostatic adsorption heating device according to claim 1, characterized in that: The number of the mounting blind holes is 18, and the mass flow meter measures and adjusts the gas pressure to 3 torr, 4 torr, 5 torr, 6 torr or 7 torr, and the number of the corresponding activated micro chucks is 12-18.

3. The wafer electrostatic adsorption heating device according to claim 2, characterized in that: When the mass flow meter monitors the gas pressure to be 3 torr, 4 torr or 6 torr, the number of micro chucks to be started is selected as 12; when the mass flow meter monitors the gas pressure to be 5 torr, the number of micro chucks to be started is selected as 15; when the mass flow meter monitors the gas pressure to be 7 torr, the number of micro chucks to be started is selected as 18.

4. The wafer electrostatic adsorption heating device according to claim 2, characterized in that: The heater substrate is in a disc shape, and the mounting blind holes are evenly distributed along the inner and outer circles on the heater substrate, with 6 blind holes distributed in the inner circle and 12 blind holes distributed in the outer circle.

5. The wafer electrostatic adsorption heating device according to claim 4, characterized in that: The heater substrate is disc-shaped, with 6 gas channels distributed at equal arcs along the radial direction, and 3 mounting blind holes distributed between two adjacent gas channels.

6. The wafer electrostatic adsorption heating device according to claim 1, characterized in that: The micro chuck comprises a base layer, an electrode layer and a ceramic outer layer, wherein the ceramic outer layer and the electrode layer are connected via an adhesive layer, the electrode layer leads out positive and negative electrodes, and the positive and negative electrodes of all micro chucks are connected in parallel and bundled together.

7. The wafer electrostatic adsorption heating device according to claim 1, characterized in that: The shape of the mounting blind hole is circular or hexagonal.

8. The wafer electrostatic adsorption heating device according to claim 1, characterized in that: A first fixing threaded hole is provided at the bottom of the mounting blind hole, and a second fixing threaded hole is provided at the bottom of the micro chuck. The first fixing threaded hole and the second fixing threaded hole are aligned with each other and the micro chuck is locked with a screw.

9. The wafer electrostatic adsorption heating device according to claim 1, characterized in that: The heater substrate is made of stainless steel, with a thickness of 20 mm and a diameter of 310 mm. The size of the mounting blind hole is a diameter of 12 mm and a groove depth of 8 mm.

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