Electrostatic chuck and reaction chamber

Abstract

The present invention provides an electrostatic chuck and a reaction chamber. The electrostatic chuck includes an insulating layer and a heating element disposed at the bottom of the insulating layer, and further includes: a cooling structure disposed below the heating element and spaced apart from the heating element, and the cooling structure is configured to transfer the heat of the heating element through a cooling liquid. The electrostatic chuck provided by the present invention can achieve stable temperature control of the heating element during the process, thereby effectively reducing whisker defects and further improving the product yield.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an electrostatic chuck and a reaction chamber. Background Art

[0002] Currently, the use of physical vapor deposition (PVD) technology to produce aluminum thin films is widely used in the semiconductor manufacturing field. However, during the Al film deposition process, impurities in the cavity cause abnormal growth of the film material, resulting in thorny or angular whisker defects. If the whisker defects are large enough, they will affect the product yield. Therefore, controlling the generation of impurities during the Al film deposition process is an important means and measure to control the occurrence of whisker defects.

[0003] When using PVD equipment to deposit Al thin films, a high-temperature electrostatic chuck (HTEC) is often used as a wafer support base to secure, support, and transport the wafer while also achieving temperature control. Conventional HTEC chucks include a temperature control device for controlling the wafer's temperature. This device uses a heater to provide heat to the insulating layer supporting the wafer, while cooling pipes cool the heater to prevent it from overheating.

[0004] However, because the heater is in direct contact with the cooling pipes, cooling water cannot be added to the cooling pipes during high-temperature operation, otherwise the water in the cooling pipes will boil. As a result, the cooling pipes are inoperative during the process, causing the temperature of the heater to gradually rise because the generated heat cannot be effectively transferred away in a timely manner. This leads to an increase in whisker defects and seriously affects product yield. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art and proposes an electrostatic chuck and a reaction chamber, which can achieve stable temperature control of the heating body during the process, thereby effectively reducing whisker defects and further improving product yield.

[0006] To achieve the purpose of the present invention, an electrostatic chuck is provided, comprising an insulating layer and a heating body disposed at the bottom of the insulating layer, and further comprising:

[0007] The cooling structure is arranged below the heating body and spaced apart from the heating body. The cooling structure is used to conduct heat from the heating body through cooling liquid.

[0008] Optionally, the cooling structure includes:

[0009] A cooling pipeline is arranged separately from the heating body;

[0010] The heat transfer plate is in the shape of a thin wall and is respectively connected to the heating body and the cooling pipeline, and is used to transfer the heat of the heating body to the cooling pipeline.

[0011] Optionally, the cooling structure further includes a flange, the flange is connected to the bottom of the heating body and surrounds the cooling pipeline;

[0012] The heat transfer plate is in a ring shape, and the inner peripheral wall and the outer peripheral wall of the heat transfer plate are respectively in contact with the cooling pipeline and the flange.

[0013] Optionally, by setting the axial thickness, radial length of different heat transfer plates and / or the contact area where the inner peripheral wall and the outer peripheral wall of the heat transfer plate are respectively in contact with the cooling pipeline and the flange, the heat dissipation efficiency of the heat transfer plate is controlled.

[0014] Optionally, the value range of the heat dissipation efficiency of the heat transfer plate is 10W - 500W.

[0015] Optionally, the value range of the distance between the cooling structure and the heating body is 2 - 30mm.

[0016] Optionally, the distance between the cooling structure and the heating body is 5mm.

[0017] Optionally, the heat transfer plate and the cooling pipeline are connected by welding.

[0018] Optionally, the cooling structure further includes:

[0019] A heat absorption structure, which is in contact with the cooling pipeline and is located below the heating body, and is used to absorb the heat radiated from the heating body.

[0020] Optionally, the heat absorption structure includes a heat absorption plate, the heat absorption plate is arranged above the cooling pipeline and is fixedly connected to the cooling pipeline; and, a plurality of heat absorption fins are arranged on the surface of the heat absorption plate opposite to the heating body.

[0021] Optionally, the plurality of heat absorption fins are a plurality of rings with different inner diameters, and the plurality of rings are concentrically arranged.

[0022] Optionally, the cooling pipeline is arranged to surround the circumference of the heat absorption plate.

[0023] As another technical solution, the present invention further provides a reaction chamber, including the above-mentioned electrostatic chuck provided by the present invention.

[0024] The present invention has the following beneficial effects:

[0025] The electrostatic chuck provided by the present invention can avoid the boiling of the cooling liquid introduced into the cooling structure during high-temperature operation by arranging the cooling structure at a distance from the heating body. At the same time, the cooling structure can transfer the heat of the heating body during the process, thereby effectively reducing whisker defects and improving the product yield.

[0026] The reaction chamber provided by the present invention can achieve stable temperature control of the heating body during the process by adopting the above-mentioned electrostatic chuck provided by the present invention, thereby effectively reducing whisker defects and improving the product yield. Description of the Drawings

[0027] Figure 1 is a structural diagram of the temperature control device of the existing electrostatic chuck;

[0028] Figure 2 is a trend diagram of the heating of the heating body and whisker defects in the prior art;

[0029] Figure 3 is a structural diagram of the temperature control device of the electrostatic chuck provided by the first embodiment of the present invention;

[0030] Figure 4 is a structural diagram of the temperature control device of the electrostatic chuck provided by the second embodiment of the present invention;

[0031] Figure 5 is a top view of the heat absorption structure adopted in the second embodiment of the present invention;

[0032] Figure 6 is a heat flow diagram of the electrostatic chuck provided by the second embodiment of the present invention;

[0033] Figure 7 is a trend diagram of the heating of the heating body and whisker defects in the second embodiment of the present invention. Detailed Description of the Invention

[0034] To enable those skilled in the art to better understand the technical solutions of the present invention, the electrostatic chuck and reaction chamber provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Figure 1 is a structural diagram of the temperature control device of the existing electrostatic chuck, as Figure 1 shown, the temperature control device includes a heating body 1 provided at the bottom of the insulating layer of the electrostatic chuck for providing heat, and a cooling pipeline 2 provided at the bottom of the heating body 1 for cooling the heating body 1.

[0036] When using a PVD device for the deposition process of an Al thin film, the process temperature of the Al thin film deposition process is usually 270 °C. The target material sputtered from the target during the process will carry a high amount of energy. When it is deposited on the wafer, it will cause the temperature of the wafer to rise, and the heat of the wafer is transferred to the heating body 1 at its bottom through the electrostatic chuck, resulting in an increase in the temperature of the heating body 1. However, since the heating body 1 is in direct contact with the cooling pipeline 2, it is impossible to introduce cooling water into the cooling pipeline 2 during high-temperature operation, otherwise the water in the cooling pipeline 2 will boil. Therefore, during the process, the cooling pipeline 2 cannot work, resulting in the temperature of the heating body 1 gradually increasing because the generated heat cannot be transferred out in a timely and effective manner. As Figure 2 shown, it is a trend chart of the heating body temperature rise and whisker defects. From Figure 2 it can be seen that as the temperature of the heating body 1 increases, the whisker defects also show an upward trend, seriously affecting the product yield.

[0037] To solve the above problems, the present invention provides an electrostatic chuck, which includes an insulating layer for carrying the workpiece to be processed, and a DC electrode is built into the insulating layer to generate an electrostatic attraction with the workpiece to be processed, thereby realizing the fixation of the workpiece to be processed. Optionally, the insulating layer is made of a ceramic material (Al2O3).

[0038] Furthermore, the electrostatic chuck provided by the present invention further includes a cooling structure, which is arranged below the heating body and is spaced apart from the heating body. The cooling structure is used to export the heat of the heating body through a cooling liquid.

[0039] By arranging the cooling structure at a distance from the heating body, it is possible to avoid the boiling of the cooling liquid introduced into the cooling structure during high-temperature operation, and at the same time, the cooling structure can export the heat of the heating body during the process, thereby effectively reducing whisker defects and further improving the product yield.

[0040] Optionally, the distance between the cooling structure and the heating body ranges from 2 to 30 mm, preferably 5 mm, so as to avoid the boiling of the cooling liquid introduced into the cooling structure during high-temperature operation and at the same time be able to transfer the heat of the heating body during the process.

[0041] The following describes the specific implementation manner of the above cooling structure in detail. Specifically, please refer to Figure 3 , the cooling structure includes a heating body 3, a cooling pipeline 5, a flange 4, and a heat transfer plate 6 arranged at the bottom of the above insulating layer. Among them, the cooling pipeline 5 is arranged below the heating body 3 and is spaced apart from the heating body 3, that is, the cooling pipeline 5 is completely not in contact with the heating body 3. Optionally, the cooling pipeline 5 can be arranged to surround the heating body 3 circumferentially.

[0042] The flange 4 is connected to the bottom of the heating body 3 and is disposed around the cooling pipeline 5. Optionally, the flange 4 can be used as a sealing flange to connect with the corrugated pipe for realizing the vacuum seal of the chamber.

[0043] Specifically, the flange 4 may include a heat transfer ring body. The upper end of the heat transfer ring body is connected to the bottom of the heating body 3, and an annular convex portion is provided at the lower end of the heat transfer ring body. The annular convex portion protrudes relative to the inner peripheral wall of the heat transfer ring body and contacts the heat transfer plate 6. Moreover, an upper flange is provided at the top of the corrugated pipe and is hermetically connected to the annular convex portion; a lower flange is provided at the bottom of the corrugated pipe and is hermetically connected to the bottom chamber wall of the reaction chamber. And, a through hole is provided in the bottom chamber wall, and the through hole is located inside the corrugated pipe. The lifting shaft extends vertically upward from the outside of the chamber through the through hole to the inside of the chamber, and the lifting shaft is sleeved inside the corrugated pipe. The upper end of the lifting shaft is connected to the upper flange, and the lower end of the lifting shaft is connected to the driving source. Driven by the driving source, the lifting shaft drives the electrostatic chuck to make a lifting motion. Thus, the seal of the chamber can be ensured.

[0044] Optionally, the annular convex portion of the flange 4 and the above-mentioned upper flange can be hermetically connected by welding. This sealing method can be applied to high-temperature chambers with high requirements for vacuum degree and particle size.

[0045] The heat transfer plate 6 is annular and thin-walled. The inner peripheral wall and the outer peripheral wall of the heat transfer plate 6 are respectively in contact with the cooling pipeline 5 and the flange 4. The heat in the heating body 1 is transferred to the heat transfer plate 6 through the flange 4 and then transferred from the heat transfer plate 6 to the cooling pipeline 5. The so-called heat transfer plate being thin-walled means that the radial thickness of the heat transfer plate is much smaller than its axial length.

[0046] By separating the cooling pipeline 5 from the heating body 3 at an interval, it is possible to prevent the cooling liquid introduced into the cooling pipeline 5 from boiling during high-temperature operation. At the same time, with the help of the heat transfer plate 6, the heat of the flange 4 can be transferred to the cooling pipeline 5, and the heat of the heating body 3 can be transferred out during the process, thereby effectively reducing whisker defects and improving the product yield. Meanwhile, using the thin-walled characteristic of the heat transfer plate 6, even if the heat transfer plate 6 contacts the flange 4, the cooling liquid in the cooling pipeline 5 will not boil, so that the heating body 3 can be cooled during the process. In addition, using the thin-walled characteristic of the heat transfer plate 6, the structure and size of the heat transfer plate can be designed according to the flat plate heat transfer principle formula, so that the heat transfer speed can be accurately controlled, and the temperature of the heating body 3 can be stably controlled during the process, and an optimal heat conduction efficiency can be obtained.

[0047] Specifically, the above-mentioned flat plate heat transfer principle formula is:

[0048] Q = λ(T1 - T2)tA / δ

[0049] Among them, Q is the heat value transferred by the heat transfer plate per second, with the unit of J; λ is the thermal conductivity of the heat transfer plate, with the unit of W / (m·K); T1 - T2 is the temperature difference between the flange and the cooling pipeline, with the unit of K; t is the heat conduction time, with the unit of s; A is the contact area, with the unit of m 2 ; δ is the thickness of the heat transfer plate, with the unit of m.

[0050] For example, the temperature T1 at the contact between the heat transfer plate 6 and the flange 4 is about 250 °C; the temperature T2 at the contact between the heat transfer plate 6 and the cooling pipeline 5 is about 40 °C; the thickness of the heat transfer plate is 0.2 mm; the contact area is 1.256 -4 m 2 . By substituting the above parameters into the flat plate heat transfer principle formula, the heat value Q transferred by the heat transfer plate per second can be calculated to be about 52 J, that is, the heat dissipation efficiency of the heat transfer plate under this working condition is 52 W.

[0051] Based on the above principle, by changing the size and contact area of the heat transfer plate 6, the heat dissipation efficiency can be controlled within the range of 10 W to 500 W.

[0052] According to the above flat plate heat transfer principle formula, by setting different axial thicknesses, radial lengths of the heat transfer plate and / or the contact areas where the inner peripheral wall and the outer peripheral wall of the heat transfer plate are respectively in contact with the cooling pipeline 5 and the flange 3, the heat dissipation efficiency of the heat transfer plate can be controlled.

[0053] Optionally, the heat transfer plate 6 and the cooling pipeline 5 are connected by welding. In addition, the heat transfer plate 6 can also be connected to the flange 4 by welding, or they can just be in contact with each other.

[0054] It should be noted that in this embodiment, the heat transfer plate 6 cools the heating element 3 through the flange 4. However, the present invention is not limited to this. In actual applications, the flange 4 can also be omitted, and the heat transfer plate 6 can be directly connected to the heating element 3 and the cooling pipeline 5 respectively. This can also transfer the heat of the heating element 3 to the cooling pipeline 5. Moreover, due to the thin wall characteristic of the heat transfer plate 6, even when the heat transfer plate 6 is in contact with the heating element 3, the cooling liquid in the cooling pipeline 5 will not boil, so that the heating element 3 can be cooled during the process.

[0055] It should also be noted that in this embodiment, the heat of the heating element 3 is transferred to the cooling pipeline 5 through the heat transfer plate 6. However, the present invention is not limited to this. In actual applications, other heat transfer methods can also be adopted for the cooling structure. For example, the cooling structure can be completely non - contact with the heating element 3. In this case, the heat of the heating element 3 can be transferred to the cooling structure through air heat radiation and heat convection.

[0056] Please refer to Figure 4, the electrostatic chuck provided by the second embodiment of the present invention is an improvement based on the above first embodiment. Specifically, the electrostatic chuck also includes an insulating layer, a heating element 3 disposed at the bottom of the insulating layer, a cooling pipeline 5, a flange 4, and a heat transfer plate 6. Since the structures and functions of these components have been described in detail in the above first embodiment, they will not be described herein again.

[0057] In this embodiment, the electrostatic chuck further includes a heat absorption structure which is in contact with the cooling pipeline 5 and is located below the heating element 3 for absorbing the heat radiated from the heating element 3. By means of the above heat absorption structure, the heat dissipation rate of the heating element 3 can be enhanced, especially the heat dissipation of the central region of the heating element 3 can be enhanced, so that the heat dissipation rate of the central region is higher than that of the edge region, thereby compensating for the temperature difference between the central region and the edge region of the heating element 3 (the temperature rise in the central region is more serious during the process), thereby improving the temperature uniformity of the heating element 3, and further improving the temperature uniformity of the workpiece to be processed.

[0058] In this embodiment, the heat absorption structure includes a heat absorption disc 7 which is disposed above the cooling pipeline 5 and is fixedly connected to the cooling pipeline 5; and a plurality of heat absorption fins 8 are disposed on the surface of the heat absorption disc 7 opposite to the heating element 3. The heat in the heating element 3 can be transferred to each heat absorption fin 8 through air heat radiation and heat convection, and then transferred to the cooling pipeline 5 through the heat absorption disc 7.

[0059] In this embodiment, as Figure 5 shown, the plurality of heat absorption fins 8 are a plurality of rings with different inner diameters, and the plurality of rings are concentrically arranged. In this way, the cooling uniformity of the heating element 3 can be improved, thereby further improving the temperature uniformity of the heating element 3.

[0060] Of course, in practical applications, the size of the heat absorption fins (including height, thickness, spacing, distribution position, etc.) can be designed according to specific needs.

[0061] Optionally, in order to improve the uniformity of heat transfer, the cooling pipeline 5 is disposed around the circumference of the heat absorption disc 7.

[0062] In addition, a central hole 71 is provided on the heat absorption disc 7 for introducing or leading out wiring such as a DC electrode or a heating electrode into or out of the electrostatic chuck.

[0063] Next, taking the PVD process as an example, the heat flow distribution of the electrostatic chuck provided by the second embodiment of the present invention will be described in detail. Please refer to Figure 6, during the PVD process, the plasma bombards the target 9 to generate metal ions. The metal ions move from the target 9 towards the surface of the wafer 11 with a certain amount of energy. After the metal ions contact the wafer 11, the energy is converted into heat and transferred to the wafer 11. At this time, the central region of the wafer 11 obtains more energy, while the edge region obtains less energy. The wafer 11 transfers the heat to the insulating layer 12 of the electrostatic chuck, and the insulating layer 12 transfers the heat to the heating body 3. The heat in the heating body 3 can be transferred to the cooling pipeline 5 through two paths simultaneously, and the heat is exported through the cooling liquid in the cooling pipeline 5. The first path is: conducted through the flange 4 to the heat transfer plate, and then transferred to the cooling pipeline 5; the second path is: transferred to the heat absorption fin 8 and the heat absorption plate 7 through air thermal radiation and thermal convection, and then transferred to the cooling pipeline 5.

[0064] As Figure 7 shown, during the process of the process, the temperature of the heating body 3 remains basically unchanged, achieving thermal equilibrium, thereby effectively reducing whisker defects.

[0065] As another technical solution, the present invention also provides a reaction chamber, which includes the electrostatic chuck provided in each of the above embodiments of the present invention.

[0066] Specifically, in this embodiment, as Figure 6 shown, the reaction chamber 10 is a PVD chamber. A target 9 is provided in the reaction chamber 10, and an electrostatic chuck is provided below the target 9. The electrostatic chuck includes an insulating layer 12 for carrying the wafer 11. And, the insulating layer 12 is fixed on the heating body 3 through a retaining ring 13.

[0067] The flange 4 is connected to the bottom of the heating body 3 and is arranged around the cooling pipeline 5. Optionally, the flange 4 can be used as a sealing flange to be connected to the corrugated pipe 15 for realizing the vacuum sealing of the chamber. Specifically, the flange 4 may include a heat transfer ring body. The upper end of the heat transfer ring body is connected to the bottom of the heating body 3, and an annular protrusion is provided at the lower end of the heat transfer ring body. The annular protrusion protrudes relative to the inner peripheral wall of the heat transfer ring body and contacts the heat transfer plate 6. And, an upper flange is provided at the top of the corrugated pipe 15, which is hermetically connected to the annular protrusion; a lower flange is provided at the bottom of the corrugated pipe 15, which is connected to the bottom chamber wall of the reaction chamber or extends outside the reaction chamber 10 and is hermetically connected to a lifting shaft (not shown in the figure). And, a through hole (not shown in the figure) is provided in the bottom chamber wall, and the through hole is located inside the corrugated pipe. The lifting shaft extends vertically upward from the outside of the chamber through the through hole to the inside of the chamber, and the lifting shaft is sleeved inside the corrugated pipe 15, and the upper end of the lifting shaft is connected to the upper flange, and the lower end of the lifting shaft is connected to the driving source. Driven by the driving source, the lifting shaft drives the electrostatic chuck to make a lifting movement. Thus, the sealing of the chamber can be ensured.

[0068] The reaction chamber provided by the present invention can achieve stable temperature control of the heating body during the process by using the above-mentioned electrostatic chuck provided by the present invention, thereby not only effectively reducing whisker defects, but also obtaining an optimal heat conduction efficiency.

[0069] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. An electrostatic chuck, comprising an insulating layer and a heating element disposed at the bottom of the insulating layer, characterized in that, Also includes: a cooling structure, disposed below the heating body and spaced apart from the heating body, the cooling structure being configured to conduct heat away from the heating body through a cooling liquid; The cooling structure comprises: A cooling pipeline is arranged separately from the heating body; a heat transfer plate, which is thin-walled and connected to the heating body and the cooling pipe respectively, and is used to transfer the heat of the heating body to the cooling pipe; The cooling structure further includes a flange, which is connected to the bottom of the heating body and surrounds the cooling pipeline; The heat transfer plate is annular, and the inner peripheral wall and the outer peripheral wall of the heat transfer plate are in contact with the cooling pipeline and the flange respectively.

2. The electrostatic chuck according to claim 1, wherein The heat dissipation efficiency of the heat transfer plate is controlled by setting different axial thicknesses, radial lengths and / or contact areas of the inner and outer circumferential walls of the heat transfer plate with the cooling pipe and the flange, respectively.

3. The electrostatic chuck according to claim 2, characterized in that, The heat dissipation efficiency of the heat transfer plate ranges from 10W to 500W.

4. The electrostatic chuck according to claim 1, wherein The distance between the cooling structure and the heating body ranges from 2 to 30 mm.

5. The electrostatic chuck according to claim 4, characterized in that, The distance between the cooling structure and the heating body is 5 mm.

6. The electrostatic chuck according to claim 1, wherein, The heat transfer plate and the cooling pipeline are connected by welding.

7. The electrostatic chuck according to any one of claims 1-6, characterized in that, The cooling structure further comprises: The heat absorption structure is in contact with the cooling pipeline and is located below the heating body, and is used for absorbing the heat radiated from the heating body.

8. The electrostatic chuck according to claim 7, wherein The heat absorbing structure includes a heat absorbing plate, which is arranged above the cooling pipeline and fixedly connected to the cooling pipeline; and a plurality of heat absorbing sheets are arranged on the surface of the heat absorbing plate opposite to the heating body.

9. The electrostatic chuck according to claim 8, wherein The plurality of heat absorbing sheets are a plurality of ring bodies with different inner diameters, and the plurality of ring bodies are concentrically arranged.

10. The electrostatic chuck according to claim 8, wherein, The cooling pipeline is arranged around the circumference of the heat absorbing plate.

11. A reaction chamber, characterized in that, The electrostatic chuck comprises the electrostatic chuck according to any one of claims 1 to 10.

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