TW202335137A - Vacuum adsorption system and method - Google Patents

Abstract

The present application relates to a vacuum adsorption system and method. The vacuum adsorption system is used for adsorbing and releasing a wafer located on a bearing surface of a vacuum adsorption type heater in a reaction chamber; the reaction chamber is provided with an air extraction opening; and the vacuum adsorption type heater is provided with an air ventilation opening. The vacuum adsorption system comprises: a first pipeline used for fluidly coupling the air extraction opening of the reaction chamber to a vacuum pump; a second pipeline used for fluidly coupling the air ventilation opening of the vacuum adsorption type heater to the vacuum pump; and a third pipeline connected to the second pipeline and used for supplying a gas from a gas source to the vacuum adsorption system. When the vacuum adsorption system is used for adsorbing the wafer, the air pressure in an adsorption pipeline inside the heater can be conveniently adjusted in the process of adsorbing and releasing the wafer, thereby adjusting the pressure difference between the back surface and the front surface of the wafer, and facilitating the improvement of the operation efficiency.

Description

Vacuum adsorption system and method

The present application relates to a device for heating a wafer in a semiconductor processing chamber, and in particular to a vacuum adsorption heater. The present application also relates to a vacuum adsorption system that can be used in conjunction with a vacuum adsorption heater, and a method of adsorbing wafers using the vacuum adsorption system.

A wafer or substrate is the base used to prepare semiconductor devices. In order to prepare semiconductor devices (such as integrated circuits, semiconductor light-emitting devices, etc.), the wafer or substrate needs to be placed in a semiconductor processing chamber (also called a reaction chamber) for heating and deposition processing (such as chemical vapor deposition (CVD) ), plasma enhanced chemical vapor deposition (PECVD), etc.) to deposit thin films on the surface of wafers or substrates. During the processing, the wafer can be fixed on the heater in the processing chamber by means of vacuum adsorption.

However, existing vacuum adsorption heaters, vacuum adsorption systems and adsorption methods have many shortcomings.

For example, the wafer bearing surface of the heater is in surface contact with the wafer, which is prone to uneven contact. For example, due to the surface roughness of the bearing surface and the wafer itself and its processing errors, etc., when the wafer is placed on the bearing surface, the two may not fit completely and evenly, and some positions may be suspended or in the middle. There are uneven gaps at different locations.

In this case, on the one hand, it may cause uneven heating of various positions of the wafer when the heater is heating, resulting in poor heating effect and even affecting the yield of the wafer; on the other hand, it may cause the wafer to be damaged during the operation. The round vacuum adsorption force is not enough and the adsorption effect is not good; the wafer may even move on the bearing surface, especially in processing chambers with large air flow and high pressure, where the possibility of wafer movement is greater.

In addition, the vacuum adsorption structures on some vacuum adsorption heaters (such as through holes on the heating plate, adsorption pipelines inside the heating plate, etc.) are difficult to process due to their small size and deep depth, making processing difficult. Processing costs are higher.

In addition, the existing vacuum adsorption system generally only uses a vacuum pump to suck the gas (air) in the adsorption pipeline inside the heater, thereby controlling the back side of the wafer (that is, the surface in contact with the wafer carrying surface of the heater). Therefore, during the process of adsorbing and releasing the wafer, the air pressure in the adsorption pipeline inside the heater can only be controlled by operating the vacuum pump (or the valve on the vacuum pump pipeline) to control the wafer. The pressure difference between the back and the front controls the adsorption force to the wafer. However, this method is very inconvenient (or even impossible) to adjust the adsorption force to the wafer as needed; moreover, during the process of releasing the wafer, the only way is to close the vacuum pump (or the valve on the vacuum pump pipeline) and allow the reaction to occur at the same time. The gas in the chamber automatically flows into the adsorption pipeline inside the heater to the back of the wafer, so that the pressure on the back of the wafer reaches approximately the same pressure as the front, thereby releasing the wafer. This whole process takes a long time, thus reducing the cost of the wafer. Improve work efficiency.

Therefore, it is necessary to improve the existing vacuum adsorption heaters, vacuum adsorption systems, and methods of adsorbing wafers using the vacuum adsorption system to solve the above technical problems.

The purpose of this application is to solve at least one of the above-mentioned problems in the prior art and provide an improved vacuum adsorption heater. The heater can form uniform point contact between the wafer placed on the bearing surface and the bearing surface, so it can not only effectively absorb the wafer during operation, but also prevent the wafer from moving on the heater bearing surface ( Even in a reaction chamber with large air flow and high pressure), the entire wafer is heated evenly, thereby improving the product quality of the wafer.

At the same time, this application also provides a vacuum adsorption system. When using this vacuum adsorption system to adsorb wafers, the air pressure in the adsorption pipeline inside the heater can be easily adjusted during the process of adsorbing and releasing the wafers, thereby adjusting the wafers. The pressure difference between the back and the front of the circle (that is, adjusting the size of the adsorption force) can not only meet the various adsorption needs of the wafer (for example, some processing processes of the wafer require greater adsorption force, while some processes require smaller adsorption force. force), and during the process of releasing the wafer, gas can be introduced to quickly increase the pressure on the back of the wafer to be equal to or even greater than the pressure on the front. Therefore, the adsorption force can be eliminated in a short time and the wafer can be released, which is beneficial to improve Operational efficiency.

This application also provides a method for adsorbing wafers using the above-mentioned vacuum adsorption system. This method can effectively adjust the adsorption force of the adsorbed wafers, so it has a wide range of applications and helps improve the efficiency of processing wafers.

Some embodiments of the present application provide a vacuum adsorption system for adsorbing and releasing wafers located on the bearing surface of a vacuum adsorption heater in a reaction chamber. The reaction chamber has an air extraction port, and the vacuum adsorption type heater has a suction port. The heater has a vent, and the above-mentioned system includes: a first pipeline, which is used to fluidly couple the air extraction port of the above-mentioned reaction chamber and the vacuum pump; a second pipeline, which is used to connect the vent of the above-mentioned vacuum adsorption heater. Fluidly coupled to the above-mentioned vacuum pump; and a third pipeline connected to the above-mentioned second pipeline and used to supply gas from the gas source to the above-mentioned vacuum adsorption system.

In some embodiments of the present application, a first valve is disposed on the second pipeline close to the vent, and the third pipeline is connected to the downstream of the first valve on the second pipeline.

In some embodiments of the present application, a second valve is disposed on the third pipeline.

In one embodiment, a gas pressure controller is further disposed on the third pipeline for regulating the flow rate of gas supplied to the vacuum adsorption system. The above-mentioned air pressure controller may include a mass flow controller, an adjustable flow valve and an air pressure measuring device.

In one embodiment, a throttle valve is installed on the first pipeline; the second pipeline bifurcates into a first manifold pipeline and a second manifold pipeline downstream of the first valve; the above-mentioned first manifold pipeline The other end of the second manifold is connected to the first pipeline between the air extraction port of the reaction chamber and the throttle valve. The third valve is placed on the first manifold; the other end of the second manifold is connected to In the above-mentioned vacuum pump, the fourth valve is arranged on the above-mentioned second manifold.

In one embodiment, an air pressure measuring device is further installed on the second manifold.

In one embodiment, the first valve, the second valve, the third valve and the fourth valve are all electromagnetic pneumatic valves.

Some embodiments of the present application also provide a method of adsorbing a wafer using the vacuum adsorption system according to any embodiment of the present application, which includes: during the process of adsorbing and/or releasing the wafer, using the above-mentioned third method. The second pipeline and the above-mentioned third pipeline supply gas from the above-mentioned gas source to the adsorption pipeline inside the above-mentioned vacuum adsorption heater to adjust the pressure difference between the back and front sides of the above-mentioned wafer, wherein the above-mentioned adsorption pipeline and The above vents are in fluid communication.

In some embodiments of the present application, during the process of adsorbing the wafer, the second pipeline and the third pipeline are used to supply gas from the gas source to the adsorption pipeline, so that the back side of the wafer The pressure should be kept 30-150 Torr less than the pressure on the front.

In some embodiments of the present application, during the process of releasing the wafer, the second pipeline and the third pipeline are used to supply gas from the gas source to the adsorption pipeline, so that the back side of the wafer The pressure rises to greater than or equal to the pressure on its front. For example, the pressure on the back side of the wafer is increased to 5-10 Torr greater than the pressure on the front side.

Some embodiments of the present application provide a method for adsorbing wafers using a vacuum adsorption system according to any embodiment of the present application, which includes the following steps: (a) Place the above-mentioned wafer: When the above-mentioned vacuum adsorption system is in a closed state, place the above-mentioned wafer on the bearing surface of the above-mentioned vacuum adsorption heater in the above-mentioned reaction chamber; (b) Adsorb the above-mentioned wafer: start the above-mentioned vacuum adsorption system, continuously suck the gas in the adsorption pipeline inside the above-mentioned vacuum adsorption heater through the above-mentioned second pipeline, so that the pressure on the back side of the above-mentioned wafer remains less than The pressure on its front side is used to adsorb the wafer on the bearing surface of the vacuum adsorption heater, wherein the adsorption pipeline is in fluid communication with the vent; and (c) Release the above-mentioned wafer: After the above-mentioned wafer is processed, stop sucking the gas in the adsorption pipeline inside the above-mentioned vacuum adsorption heater, and use the above-mentioned second pipeline and the above-mentioned third pipeline to remove the gas from the above-mentioned wafer. The gas from the gas source is supplied to the adsorption pipeline to increase the pressure on the back side of the wafer to be equal to or greater than the pressure on the front side of the wafer to release the wafer.

In some embodiments, the above method further includes at least one of the following steps: (a1) Before step (a), heat the above-mentioned bearing surface of the above-mentioned vacuum adsorption heater (for example, heated to 450-500°C), and pump the above-mentioned reaction chamber to a vacuum state by the above-mentioned vacuum pump; and (a2) After step (a) and before step (b), inject gas into the reaction chamber to increase the gas pressure in the reaction chamber.

In some embodiments, in step (a2), when the gas pressure in the reaction chamber rises to exceed a threshold value (eg, 100 Torr), step (b) is started.

In some embodiments, in step (b), while the vacuum pump is used to continuously suck the gas in the adsorption pipeline in the vacuum adsorption heater through the second pipeline, the gas in the adsorption pipeline in the vacuum adsorption heater is pumped through the second pipeline. The second pipeline and the third pipeline supply gas from the gas source to the adsorption pipeline, so that the air pressure on the back side of the wafer is kept 30-150 Torr lower than the air pressure on the front side of the wafer.

As mentioned above, in some embodiments of the present application, a throttle valve is installed on the first pipeline; a first valve is installed on the second pipeline near the vent; and the third pipeline is connected to the second pipeline. Downstream of the above-mentioned first valve on the pipeline, a second valve is installed on the above-mentioned third pipeline; the above-mentioned second pipeline bifurcates into a first manifold pipeline and a second manifold pipeline downstream of the above-mentioned first valve; The other end of the first manifold is connected to the first pipe between the air extraction port of the reaction chamber and the throttle valve, a third valve is placed on the first manifold; and the second manifold is The other end is connected to the above-mentioned vacuum pump, and the fourth valve is placed on the second manifold.

In some embodiments, during step (a1), the above-mentioned first valve, the above-mentioned second valve, the above-mentioned third valve, and the above-mentioned fourth valve are all closed, and the above-mentioned throttle valve is opened.

In some embodiments, during step (b), the first valve, the second valve and the fourth valve are all open, and the third pneumatic valve is closed.

In some embodiments, in step (b), the flow rate of the gas in the third pipeline (C) is adjusted so that the air pressure on the back side of the wafer remains 30-150 Torr smaller than the air pressure on the front side of the wafer.

In some embodiments, during the execution of the above step (c), the above-mentioned first valve, the above-mentioned second valve and the above-mentioned third valve are all opened, and the above-mentioned fourth valve is closed.

In some embodiments, in step (c), the flow rate of the gas in the third pipeline is adjusted so that the pressure on the back side of the wafer is increased to be equal to or greater than the pressure on the front side of the wafer. For example, the flow rate of the gas in the third pipeline (C) is adjusted so that the pressure on the back side of the wafer is increased to 5-10 Torr greater than the pressure on the front side.

The embodiments of the present application are described in detail below with reference to the accompanying drawings. It will be easier to understand various aspects of the present application by reading the following description of specific embodiments with reference to the accompanying drawings. It should be noted that these embodiments are only exemplary and are only used to explain and illustrate the technical solutions of the present application, but are not intended to limit the present application. Those skilled in the art can make various modifications and transformations based on these embodiments (such as changing the size and/or layout of grooves and protrusions on the upper surface of the main body of the heating plate, etc.). All technical solutions obtained through equivalent transformations belong to the protection scope of this application.

The names of various components used in this manual are for illustrative purposes only and do not have a limiting effect. Different manufacturers may use different names to refer to components with the same function. Vacuum Adsorption Heater FIG. 1 is a schematic three-dimensional view of the overall structure of a vacuum adsorption heater according to an embodiment of the present application. As shown in FIG. 1 , the vacuum adsorption heater mainly includes a heating plate 10 . The heating plate 10 includes a generally plate-shaped main body 1 and a support shaft 2 located below the main body 1 .

As shown in Figure 1, the main body 1 has an upper surface 11 for carrying the wafer. During the working process, the main body 1 of the heating plate 10 is located in a reaction chamber, and the wafer (not shown in the figure) can be placed on the upper surface 11 of the main body 1 by a transfer device such as a robot, and then vacuum adsorbed way to fix it. After the wafer is fixed, it can be subjected to operations such as deposition processing.

Referring to Figure 1 in conjunction with Figures 9 to 12, in some embodiments of the present application, the main body 1 of the heating plate 10 and the support shaft 2 located below the main body 1 are formed into one body. For example, both of them can be made of ceramics, and then they can be integrated into one by adhesion or welding. Compared with the heating plate that adopts a split structure (that is, the main body and the support shaft are detachably assembled together), the integrated structure in this application not only eliminates the need for installation, fixation and sealing of the two. steps, and also eliminates the sealing element between the two, and the sealing performance is greatly improved, thus effectively improving the vacuum adsorption effect.

Continuing to refer to Figures 1 and 9 to 12, in terms of external structure, the vacuum adsorption heater further includes a cooling block 50 located outside the support shaft 2 and at least partially surrounding the support shaft 2, and a cooling block 50 located outside the cooling block 50 and sandwiched between The fixed block 60 holds the cooling block 50. The fixing block 60 is used to fix the vacuum adsorption heater on the machine platform. The specific structures of the cooling block 50 and the fixed block 60 can adopt designs known in the art, and will not be described again here.

In terms of internal structure, the vacuum adsorption heater further includes a heating element (not shown in the figure) located inside the main body 1 and a heating rod 40 electrically connected to the heating element. Heating elements may include, but are not limited to, resistance wires. The heating rod 40 may include a material with good electrical conductivity, such as copper, nickel, etc. The heating element, the heating rod 40 and the electrical connections between them can adopt designs known in the art, and will not be described again here.

As shown in Figures 10 and 12, the support shaft 2 has a hollow structure, and its interior can accommodate a plurality of sequentially stacked quartz blocks 20 and/or polyetheretherketone (PEEK) blocks 30. The heating rod 40 is located inside the support shaft 2 and penetrates the quartz block 20 and/or the PEEK block 30, and can be electrically connected to an external power source. When the power is turned on, the heating element will generate heat and transfer the heat to the wafer on the main body 1 of the heating plate 10 . The heating rod 40 also generates heat. The quartz block 20 and the PEEK block 30 surrounding the heating rod 40 help to keep the heat inside the support shaft 2 from basically not dissipating or dissipating very little, thereby helping to transfer the heat to the wafer to heat it. The quartz block 20 and the PEEK block 30 are also used to achieve electrical insulation between components inside the support shaft 2 .

In this application, the structure of the main body 1 of the heating plate 10 (especially the upper surface 11 carrying the wafer) is specially designed. Details are as follows.

Referring to Figures 1, 2 and 2A, Figure 2 is a top view of the heating plate 10 shown in Figure 1, and Figure 2A is an enlarged view of position A in Figure 2. In this application, the main body 1 of the heating plate 10 further has the following structure: a plurality of grooves 12 extending downward from the upper surface 11, at least a portion of the grooves 12 being in fluid communication with each other; one or more through holes 13 in fluid communication with at least one groove 12; and A plurality of bumps 14 are located on the upper surface 11 for supporting the wafer.

In some embodiments provided in this application, the plurality of grooves 12 and the plurality of protrusions 14 are substantially evenly distributed on the upper surface 11 . Those skilled in the art will understand that the plurality of grooves 12 and the plurality of protrusions 14 may not be evenly distributed, or one of them may be evenly distributed. For example, in some embodiments, the plurality of grooves 12 are generally evenly distributed, while the plurality of protrusions 14 are unevenly distributed (for example, the protrusions in the middle part are denser, while the protrusions in the surrounding part are sparse); in some cases In the embodiment, the plurality of protrusions 14 are generally evenly distributed, while the plurality of grooves 12 are unevenly distributed (for example, closer to the middle part, the grooves are denser, and toward the outer periphery, the grooves are sparser).

Different from the prior art, in this application, since the upper surface 11 has bumps 14, the wafer can form uniform point contact with the upper surface 11 of the main body of the heating plate, and there can be a uniform gap between them, that is, , these bumps 14 make the contact between the wafer and its carrying surface (that is, the upper surface 11 of the main body 1) more uniform, thus helping to provide uniform adsorption and uniform heating to each part of the wafer, thereby facilitating Processing of wafers helps ensure the film quality on the wafer surface and improves its pass rate.

In some embodiments of the present application, as shown in FIGS. 1 and 2 , the plurality of grooves 12 include a plurality of annular grooves 121 arranged in concentric circles and radial grooves 122 fluidly communicating the annular grooves 121 . In one embodiment, all radial grooves 122 are in fluid communication with adjacent annular grooves 121, so that all annular grooves 121 and radial grooves 122 are in fluid communication. Therefore, all grooves 12 are in complete fluid communication. Therefore, by vacuuming one groove 12, all grooves 12 can be vacuumed, thereby providing adsorption force to the wafer.

In some embodiments of the present application, the width of the annular groove 121 and the radial groove 122 are both 0.5-1.5 mm, and the depth is less than or equal to 1.0 mm; the spacing between adjacent annular grooves 121 is 10-1.5 mm. 50mm. More preferably, the width of the annular groove 121 and the radial groove 122 is 0.5-1.0 mm, and the depth is less than or equal to 0.5 mm; the distance between adjacent annular grooves 121 is 15-50 mm. Grooves with the above size range not only facilitate processing, but also help to effectively achieve adsorption of wafers. For illustrative purposes only, the drawings of this application show specific numbers of annular grooves 121 and radial grooves 122 . It should be understood that the heating plate 10 may have any suitable number of annular grooves 121 and radial grooves 122.

Further, as shown in Figure 2 and Figure 2A, in some embodiments of the present application, the main body 1 may only include one through hole 13, and the through hole 13 is located at a groove 12, such as the innermost annular groove. on the groove 121 and thus in fluid communication with the annular groove 121, as shown in Figure 2A. In other embodiments, the through hole 13 can also be located in other grooves 12 . In addition, as shown in FIG. 2A , the diameter of the through hole 13 is larger than the width of the groove 12 , for example, it can be 0.8-1.8 mm. Since the through hole is deep, the through hole 13 with a diameter within this size range is easy to process and can achieve a good adsorption effect. Providing only one through hole 13 also simplifies the processing technology and saves processing costs. In other embodiments, the main body 1 may also be provided with multiple through holes 13 .

In some embodiments of the present application, as shown in the figure, each bump 14 may be substantially circular, but the present application is not limited thereto. When making the main body 10 of the heating plate 1, the bumps 14 can be directly sintered and formed on the upper surface 11. In some embodiments, the diameter of each bump 14 is 1.0-3.0 mm, and the height is less than or equal to 0.2 mm; the distance between adjacent bumps 14 is 3-20 mm. The bumps with this size range are not only easy to process and form (for example, to facilitate the design of the mold of the main body 1 of the heating plate 10), but also can effectively achieve uniform contact with the wafer. Preferably, the diameter of each bump 14 is 1.5-2.5 mm, and the height is less than or equal to 0.1 mm; the distance between adjacent bumps 14 is 5-15 mm. Bumps with this size range are more conducive to their production and processing, and also help to provide uniform contact with the wafer.

In order to achieve better technical effects, when designing the structure of the upper surface 11 of the main body 1 of the heating plate 10, it is necessary to consider the distribution of the grooves 12 and the distribution of the bumps 14. Several exemplary examples will be described below with reference to the accompanying drawings. plan. It should be understood that the distribution manner of the grooves 12 and the protrusions 14 is not limited to these solutions.

In the first type of solution, as shown in FIGS. 2 to 4 , the upper surface 11 of the main body 1 includes a total of seven annular grooves 121 . The width of the annular groove 121 and the radial groove 122 are both 1.0 mm and the depth is 0.5 mm; and the distance between adjacent annular grooves 121 is 21.5 mm. In this type of solution, the annular grooves 121 are relatively dense, thus making the adsorption force more uniform during the working process and the adsorption effect on the wafer is good.

In the first embodiment of such a solution, as shown in Figure 2, the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed along the circumference, thereby forming multiple concentric circles. , the distance between adjacent bumps 14 located on the same circumference and between adjacent circumferences is 7 mm. This type of structure helps achieve uniform support of the wafer from the circumferential direction.

In a second embodiment of such a solution, as shown in FIG. 3 , the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed in a triangle (for example, the three closest ones are Each bump 14 can form an equilateral triangle), and the distance between adjacent bumps 14 is 10 mm.

In a third embodiment of such a solution, as shown in FIG. 4 , the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed in a triangle (for example, the three closest ones are Each bump 14 can form an equilateral triangle), and the distance between adjacent bumps 14 is 5 mm.

In the second type of solution, as shown in FIGS. 5 to 8 , the upper surface 11 of the main body 1 includes a total of four annular grooves 121 . The width of the annular groove 121 and the radial groove 122 are both 1.0 mm and the depth is 0.5 mm; and the distance between adjacent annular grooves 121 is 43 mm. In this type of solution, the annular grooves 121 are relatively sparse, and the heating plate 10 with such a structure is easier to produce and process, and the mold design and manufacturing are more convenient, thus reducing the production cost.

In the first embodiment of such a solution, as shown in Figure 5, the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed along the circumference, thereby forming multiple concentric circles. , the distance between adjacent bumps 14 located on the same circumference and between adjacent circumferences is 7mm. This type of structure helps achieve uniform support of the wafer from the circumferential direction.

In the second embodiment of this type of solution, as shown in Figure 6, the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed along the circumference to form multiple concentric circles. , the distance between adjacent bumps 14 located on the same circumference and between adjacent circumferences is 15mm. In this type of structure, the bumps 14 are more sparse, thus facilitating processing.

In the third embodiment of this type of solution, as shown in Figure 7, the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed in a triangle (for example, the three closest ones are Each bump 14 can form an equilateral triangle), and the distance between adjacent bumps 14 is 10 mm.

In the fourth embodiment of this type of solution, as shown in Figure 8, the diameter of each bump 14 is 2.0 mm and the height is 0.1 mm; and the plurality of bumps 14 are distributed in a triangle (for example, the three closest ones are Each bump 14 can form an equilateral triangle), and the distance between adjacent bumps 14 is 5 mm.

Those skilled in the art can understand that the distance between adjacent annular grooves 121 is the distance between corresponding points of the two annular grooves, that is, the outermost edge (or centerline or The distance between the corresponding point on the innermost edge) and the corresponding point on the outermost edge (or centerline or innermost edge) of another annular groove 121. The width of the groove refers to the distance between corresponding points on the two edges of the groove, and the depth refers to the distance from the bottom surface of the groove to the top edge of the groove. Similarly, the distance between adjacent bumps 14 also refers to the distance between corresponding points on the two bumps 14 (for example, the center of the circle of the bumps).

Referring further to Figure 12 and Figure 12A, Figure 12 is a cross-sectional view showing part of the internal structure of the vacuum adsorption heater. Figure 12A is an enlarged view of D in Figure 12, which particularly shows the protrusions on the main body 1 of the heating plate 10. The structure of points 14, grooves 12, and through holes 13 in the vertical direction. As shown in FIG. 12A , the diameter of the through hole 13 is larger than the width of the groove 12 . In some embodiments, the diameter of the through hole 13 may be 0.8-1.8 mm. This type of dimensional design not only facilitates the processing of the through hole 13, but also helps achieve a good adsorption effect.

As shown in Figure 12, the vacuum adsorption heater also includes a through hole 131 that penetrates the quartz block 20 and/or the PEEK block 30. The upper end of the through hole 131 is in fluid communication with the through hole 13, and the lower end can be fluidized during operation. Coupled to a vacuum pump, the vacuum pump can suck the gas in the groove 12 through the pipeline and the through holes 131 and 13 to create a pressure difference between the back and front of the wafer, thereby adsorbing the wafer. In some embodiments, the diameter of the through hole 131 is 2-3 mm; the depth of the through hole 131 in each quartz block 20 or PEEK block 30 is 20-25 mm. Through-holes with this depth and diameter facilitate processing and production.

In order to improve the adsorption effect, as shown in Figure 12, the vacuum adsorption heater further includes a sealing ring 16 located on the quartz block 20 and/or the PEEK block and around the through hole 131, thereby improving the sealing effect and preventing or reducing gas leaked.

In addition, as shown in FIG. 12 , the vacuum adsorption heater also includes a sealing ring 15 located between the heating rod 40 and the quartz block 20 and/or the PEEK block 30 . The sealing ring 15 is sleeved on the heating rod 40 and clamped between adjacent quartz blocks 20 and/or PEEK blocks 30, so that it can be firmly fixed. Vacuum Adsorption System and Method for Adsorbing Wafers The following describes the vacuum adsorption system provided by the present application and the method for adsorbing wafers using the vacuum adsorption system. The vacuum adsorption system can be used in conjunction with the vacuum adsorption heater described in this specification or with a vacuum adsorption heater with other structures to adsorb the wafer.

Referring to Figure 13, a vacuum adsorption system according to an embodiment of the present application is schematically shown. The system is used to adsorb and release wafers (in the figure) located on the bearing surface of the vacuum adsorption heater 200 in the reaction chamber 100 (for example, the upper surface 11 of the main body 1 of the heating plate 10 shown in Figure 1 ). not shown). The reaction chamber 100 has an exhaust port 101; the vacuum adsorption heater 200 has a vent 201 (for example, the vent 201 can be in fluid communication with the through hole 131 shown in Figure 12). Although the figure shows that the entire vacuum adsorption heater 200 is located in the reaction chamber 100, in an actual product, there may be only a part of the vacuum adsorption heater 200, such as the main body 1 and the main body 1 of the heating plate 10 shown in Figure 1. A part of the support shaft 2 (for example, the part above the cooling block 50 (including the cooling block 50)) is located in the reaction chamber 100.

As shown in Figure 13, the vacuum adsorption system includes: The first pipeline A is used to fluidly couple the air extraction port 101 of the reaction chamber 100 and the vacuum pump 300; The second pipeline B is used to fluidly couple the vent 201 of the vacuum adsorption heater 200 with the vacuum pump 300; and The third pipeline C is connected to the second pipeline B and is used to supply gas from the gas source 400 to the above-mentioned vacuum adsorption system. In some embodiments, the gas in the gas source 400 may be nitrogen. Nitrogen is relatively cheaper and less prone to chemical reactions. In other embodiments, other gases, such as helium, may also be used.

According to embodiments of the present application, the gas in the gas source 400 can be supplied to the vacuum adsorption system as needed during operation through the third pipeline C fluidly coupled with the gas source 400 . Therefore, when using this vacuum adsorption system to adsorb wafers, the adsorption pipeline inside the heater (for example, the through hole 13 and the through hole 131 shown in Figure 12) can be easily adjusted during the process of adsorbing and releasing the wafer. The air pressure in the wafer is used to adjust the pressure difference between the back and front of the wafer, thereby achieving the purpose of adjusting the adsorption force. It goes without saying that this will help meet the various adsorption needs of the wafer. For example, when the wafer processing process requires a large adsorption force, only a smaller amount of gas or no gas can be introduced from the gas source 400 to ensure that the vacuum adsorption system generates adsorption force for the wafer; In a process with a smaller adsorption force, a larger amount of gas can be introduced from the gas source 400 into the vacuum adsorption system to offset part of the adsorption force generated by the vacuum pump 300 .

Another technical effect produced by arranging the third pipeline C is: during the process of releasing the wafer, gas can be introduced from the gas source 400 into the interior of the vacuum adsorption system, thereby supplying the gas to the adsorption pipeline inside the heater. , causing the pressure on the back of the wafer to quickly rise to equal to or even greater than the pressure on the front, thus eliminating the adsorption force on the wafer in a short time and releasing the wafer. Compared with the existing solution that only relies on turning off the vacuum adsorption system and allowing the gas in the reaction chamber to automatically flow to the back of the wafer, the solution of this application greatly improves the operating efficiency.

The structure of the vacuum adsorption system according to some embodiments of the present application is further described below.

Referring to FIG. 13 , in the vacuum adsorption system, a throttle valve TV is installed on the first pipeline A to control the suction of gas in the reaction chamber 100 by the vacuum pump 300 . In some embodiments, the air pressure Pc in the reaction chamber 100 can be measured by the air pressure measuring device 102 (such as a barometer or vacuum gauge). The throttle valve TV can be adjusted according to the air pressure Pc in the reaction chamber 100 to control the gas flow in the first pipeline A, thereby controlling the air pressure Pc in the reaction chamber 100 to reach a required level.

As shown in Figure 13, a first valve CHCV-1 is installed on the second pipeline B near the vent 201, and the third pipeline C is connected to the downstream of the first valve CHCV-1 on the second pipeline B ( That is, the side closer to the vacuum pump 300). The third pipeline C is provided with a second valve CHCV-2. In one embodiment, a gas pressure controller 401 is disposed on the third pipeline C for adjusting the flow rate of gas supplied to the vacuum adsorption system. As shown in the figure, the air pressure controller 401 may include a mass flow controller MFM, an adjustable flow valve 402 and an air pressure measuring device 403 (such as a barometer or vacuum gauge). Those familiar with this technology should understand that the air pressure controller 401 is not limited to the structure shown in the figure. Any existing air pressure controller or a device with similar functions can be used as the air pressure controller 401 .

Referring further to Figure 13, the second pipeline B branches into a first manifold B1 and a second manifold B2 downstream of the first valve CHCV-1; the other end of the first manifold B1 is connected to the reaction chamber. On the first pipeline A between the air extraction port 101 of 100 and the throttle valve TV, the third valve CHCV-3 is placed on the first manifold B1; the other end of the second manifold B2 is connected to the vacuum pump 300. In one embodiment, the other end of the second manifold B2 may be connected to the first pipeline A between the vacuum pump 300 and the throttle valve TV. The fourth valve CHCV-4 is disposed on the second manifold line B2. In one embodiment, an air pressure measuring device 500 (such as a barometer or a vacuum gauge) can also be installed on the second manifold line B2 to measure the air pressure Pb in the second manifold line B2, which can reflect the internal pressure of the heater. The air pressure in the adsorption pipeline.

In some embodiments, the first valve CHCV-1, the second valve CHCV-2, the third valve CHCV-3 and the fourth valve CHCV-4 are all electromagnetic pneumatic valves, which can be fully opened or closed as needed, so that Realize the control of opening and closing of corresponding pipelines. The use of electromagnetic pneumatic valves can achieve more precise control. In other embodiments, other types of valves may be used.

This application also provides a method for adsorbing wafers using the above vacuum adsorption system. In short, in this method, during the process of adsorbing and/or releasing the wafer, the second pipeline B and the third pipeline C can be used to supply the gas from the gas source 400 to the adsorption pipeline inside the heater. , to adjust the pressure difference between the back and front sides of the wafer.

According to some embodiments of the present application, during the process of adsorbing the wafer, the second pipeline B and the third pipeline C can be used to supply gas from the gas source 400 to the adsorption pipeline inside the heater, so that the wafer Maintain the required pressure difference between the backside and the front side of the wafer, for example, keep the pressure on the backside of the wafer 30-150 Torr smaller than the pressure on the front side. During the process of releasing the wafer, the second pipeline B and the third pipeline C can be used to supply the gas from the gas source 400 to the adsorption pipeline inside the heater, so that the pressure on the back side of the wafer is increased to greater than or Equal to the pressure on the front side, for example, the pressure on the back side of the wafer is increased to 5-10 Torr greater than the pressure on the front side. At this time, the adsorption force is completely eliminated and there is a certain push force on the back of the wafer, so the wafer can be easily moved to the next station.

Overall, according to some embodiments of the present application, the method of using the above-mentioned vacuum adsorption system to adsorb wafers mainly includes the following steps: (a) Place the wafer: When the vacuum adsorption system is in a closed state (that is, the second pipeline B and the third pipeline C are both in a closed state), place the wafer in the reaction chamber 100 On the bearing surface of the vacuum adsorption heater 200; (b) Adsorb the wafer: start the vacuum adsorption system, continuously suck the gas in the adsorption pipeline inside the vacuum adsorption heater 200 through the second pipeline B, so that the pressure on the back of the wafer is kept smaller than the pressure on the front. , thereby adsorbing the wafer on the bearing surface of the vacuum adsorption heater 200; and (c) Release the wafer: After the wafer is processed, stop suctioning the gas in the adsorption pipeline inside the vacuum adsorption heater 200, and use the second pipeline B and the third pipeline C to remove the gas from the gas source. The gas of 400 is supplied to the adsorption pipeline inside the vacuum adsorption heater 200, so that the pressure on the back side of the wafer is increased to be equal to or greater than the pressure on the front side, so as to release the wafer.

In some embodiments, the above method may further include at least one of the following steps: (a1) Before step (a), heat the bearing surface of the vacuum adsorption heater 200 (for example, heated to 450-500°C), and pump the reaction chamber 100 to a vacuum state by the vacuum pump 300; and (a2) After step (a) and before step (b), inject gas into the reaction chamber 100 (can be through other pipelines, not shown in the figure) to increase the gas pressure Pc in the reaction chamber 100 (according to If necessary, Pc can be raised to 200~600Torr, and the air pressure above the throttle valve TV can reach 200Torr).

In one embodiment of the present application, in step (a2), when the air pressure Pc in the reaction chamber 100 rises to exceed a threshold value (eg, 100 Torr), step (b) is started. In step (b), while the vacuum pump 300 is used to continuously suck the gas in the adsorption pipeline inside the vacuum adsorption heater 200 through the second pipeline B, the gas in the adsorption pipeline inside the vacuum adsorption heater 200 can be pumped through the second pipeline B and the third pipeline B. Pipe C supplies gas from the gas source 400 to the adsorption pipeline inside the vacuum adsorption heater 200, thereby keeping the pressure on the back side of the wafer 30-150 Torr smaller than the pressure on the front side. The specific pressure difference can be adjusted according to the needs of wafer adsorption.

As mentioned above, the first pipeline A is equipped with the throttle valve TV; the second pipeline B is equipped with the first valve CHCV-1 near the vent 201; the third pipeline C is connected to the second pipeline B downstream of the first valve CHCV-1, and a second valve CHCV-2 is installed on the third pipeline C; the second pipeline B branches into the first manifold pipeline B1 downstream of the first valve CHCV-1 and the second manifold B2; the other end of the first manifold B1 is connected to the first pipeline A between the air extraction port 101 of the reaction chamber 100 and the throttle valve TV, and the third valve CHCV-3 is placed on on the first manifold B1; the other end of the second manifold B2 is connected to the vacuum pump 300 (for example, connected to the first pipeline A between the vacuum pump 300 and the throttle valve TV, as shown in Figure 13) , the fourth valve CHCV-4 is placed on the second manifold line B2. The specific working processes of these valves and their corresponding pipelines are as follows:

In step (a1), the first valve CHCV-1, the second valve CHCV-2, the third valve CHCV-3, and the fourth valve CHCV-4 are all closed, and the throttle valve TV is opened, so that only the first pipeline A is in the passage state, whereby the vacuum pump 300 draws the reaction chamber 100 to a vacuum state. The valves remain in this state during step (a) (ie, placing the wafer) and step (a2).

In step (b) (ie, adsorbing the wafer), the first valve CHCV-1, the second valve CHCV-2, and the fourth valve CHCV-4 are all opened, and the third valve CHCV-3 is closed. The vacuum pump 300 continues to pump the gas in the reaction chamber 100 through the first pipeline A to maintain the gas pressure Pc in the reaction chamber 100 at a required level (for example, 200 Torr). At this time, the second pipeline B, the second manifold pipeline B2 and the third pipeline C are in a passage state, whereby the vacuum pump 300 sucks the gas (that is, the wafer) in the adsorption pipeline inside the vacuum adsorption heater 200 the gas on the back). At the same time, the gas source 400 can introduce gas into the vacuum adsorption system, and the amount of the introduced gas (that is, the flow rate of the gas in the third pipeline C) can be controlled by adjusting the air pressure controller 401. The vacuum pump 300 draws gas from the adsorption pipeline of the vacuum adsorption heater 200 through the second pipeline B and the second manifold pipeline B2, and the gas source 400 passes into the adsorption pipeline through the third pipeline C. Under the combined action of the incoming gas, the pressure on the back side of the wafer is kept 30-150 Torr smaller than the pressure on the front side. The specific pressure difference can be set as needed.

In step (c) (ie, releasing the wafer), the first valve CHCV-1, the second valve CHCV-2, and the third valve CHCV-3 are all opened, and the fourth valve CHCV-4 is closed. The vacuum pump 300 continues to pump the gas in the reaction chamber 100 through the first pipeline A to maintain the gas pressure Pc in the reaction chamber 100 at a required level (for example, 200 Torr). At this time, on the one hand, the gas in the reaction chamber 100 can enter the adsorption pipeline inside the vacuum adsorption heater through the first pipeline A, the first manifold pipeline B1 and the second pipeline B, thereby reaching the wafer. On the other hand, the external gas (such as nitrogen) from the gas source 400 enters the adsorption pipeline inside the vacuum adsorption heater through the third pipeline C and the second pipeline B, thereby reaching the back side of the wafer. . Due to the effect of these two gases, the pressure on the back side of the wafer rises rapidly, and the pressure difference between it and the front side quickly decreases. The flow rate of the gas on the third pipeline C can even be adjusted by adjusting the air pressure controller 401 , so that the pressure on the back side of the wafer is increased to be equal to or greater than the pressure on the front side, for example, the pressure on the back side of the wafer is increased to 5-10 Torr greater than the pressure on the front side, so as to quickly eliminate the adsorption force, and then quickly The purpose of releasing the wafer. Obviously, this mode of operation greatly improves work efficiency.

The technical content and technical features of the present application have been described by the above-mentioned relevant embodiments. However, the above-mentioned embodiments are only examples for implementing the present application. Those skilled in the art may still make various substitutions and modifications based on the teachings and disclosures of this application without departing from the spirit of this application. Therefore, the disclosed embodiments of this application do not limit the scope of this application. On the contrary, modifications and equivalent arrangements that do not depart from the spirit and scope of the present application are included in the scope of the present application.

1:Subject 2: Support shaft 10:Heating plate 11: Upper surface 12: Groove 13:Through hole 14:Bump 15, 16:Sealing ring 20:quartz block 30: Polyetheretherketone block 40:Heating rod 50: cooling block 60: Fixed block 100:Reaction chamber 101:Exhaust port 102, 403, 500: Air pressure measuring device 121: Annular groove 122: Radial groove 131:Through hole 200: Vacuum adsorption heater 201:Vent 300: Vacuum pump 400:Gas source 401:Air pressure controller 402: Adjustable flow valve A:First pipeline B: Second pipeline B1: First manifold line B2: Second manifold line C:Third pipeline CHCV-1: The first valve CHCV-2: Second valve CHCV-3: The third valve CHCV-4: The fourth valve D: Part MFM: mass flow controller Pb, Pc: air pressure TV: Throttle valve

In order to explain the specific implementation manner of the present application and the technical effects produced more clearly, the specific embodiments of the present application are described below in conjunction with the accompanying drawings. For clarity of expression and ease of layout, the drawings are not entirely to scale. For example, some are enlarged to show local details, while others are reduced to show the overall structure. For purposes of clarity, the drawings may not show all components of a given device or apparatus. Finally, throughout the specification and drawings, the same reference numbers are used to refer to the same features. in: Figure 1 is a three-dimensional schematic diagram of the overall structure of a vacuum adsorption heater according to certain embodiments of the present application; Figure 2 is a top view of the heating plate of the vacuum adsorption heater shown in Figure 1, which more clearly shows the grooves and grooves in the upper surface of the main body of the heating plate (that is, the surface used to carry the wafer). The first distribution method of bumps; Figure 2A is an enlarged view of A in Figure 2, which particularly shows that the through hole on the heating plate is located in the annular groove of the innermost ring, and the diameter is greater than the width of the annular groove; Figure 3 is similar to Figure 2. It is also a top view of the heating plate, showing the second distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 4 is also similar to Figure 2. It is also a top view of the heating plate, showing a third distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 5 is also similar to Figure 2. It is also a top view of the heating plate, showing the fourth distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 6 is also similar to Figure 2. It is also a top view of the heating plate, showing the fifth distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 7 is also similar to Figure 2. It is also a top view of the heating plate, showing the sixth distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 8 is also similar to Figure 2. It is also a top view of the heating plate, showing the seventh distribution pattern of grooves and protrusions on the upper surface of the heating plate; Figure 9 is a front view of the vacuum adsorption heater shown in Figure 1, which shows the front structure of the vacuum adsorption heater; Figure 10 is a B-B cross-sectional view of Figure 9, which shows the internal structure of the vacuum adsorption heater at the cross-sectional position; Figure 11 is a left side view of the vacuum adsorption heater shown in Figure 1, which shows the structure of the side of the heater; Figure 12 is a C-C cross-sectional view of Figure 11, which shows the internal structure of the vacuum adsorption heater at the cross-sectional position; Figure 12A is an enlarged view of D in Figure 12, which generally schematically shows the structure of bumps, grooves, and through holes in the vertical direction; and Figure 13 is a schematic structural diagram of a vacuum adsorption system according to certain embodiments of the present application.

1:Subject

2: Support shaft

10:Heating plate

11: Upper surface

12: Groove

14:Bump

50: cooling block

60: Fixed block

121: Annular groove

122: Radial groove

Claims (24)

A vacuum adsorption system used to adsorb and release wafers on the bearing surface of a vacuum adsorption heater (200) located in a reaction chamber (100), the reaction chamber (100) having an air extraction port (101) , the vacuum adsorption heater (200) has a vent (201), and the system includes: The first pipeline (A) is used to fluidly couple the air extraction port (101) of the reaction chamber (100) and the vacuum pump (300); The second pipeline (B) is used to fluidly couple the vent (201) of the vacuum adsorption heater (200) and the vacuum pump (300); and A third pipeline (C) is connected to the second pipeline (B) and is used to supply gas from the gas source (400) to the vacuum adsorption system. For example, in the vacuum adsorption system of claim 1, a first valve (CHCV-1) is installed on the second pipeline (B) near the vent (201), and the third pipeline (C) is connected to the third pipeline (C). Downstream of the first valve (CHCV-1) on the second pipeline (B). Such as the vacuum adsorption system of claim 2, wherein a second valve (CHCV-2) is installed on the third pipeline (C). The vacuum adsorption system of claim 3, wherein the third pipeline (C) is further provided with a gas pressure controller (401) for regulating the flow rate of gas supplied to the vacuum adsorption system. The vacuum adsorption system of claim 4, wherein the air pressure controller (401) includes a mass flow controller (MFM), an adjustable flow valve (402) and an air pressure measuring device (403). For example, the vacuum adsorption system of claim 3, wherein: A throttle valve (TV) is installed on the first pipeline (A); The second pipeline (B) branches into a first manifold pipeline (B1) and a second manifold pipeline (B2) downstream of the first valve (CHCV-1); The other end of the first manifold (B1) is connected to the first pipeline (A) between the air extraction port (101) of the reaction chamber (100) and the throttle valve (TV). Three valves (CHCV-3) are placed on the first manifold (B1); The other end of the second manifold (B2) is connected to the vacuum pump (300), and a fourth valve (CHCV-4) is disposed on the second manifold (B2). The vacuum adsorption system of claim 6, wherein a pressure measuring device (500) is further installed on the second manifold line (B2). For example, the vacuum adsorption system of claim 6, wherein the first valve (CHCV-1), the second valve (CHCV-2), the third valve (CHCV-3) and the fourth valve (CHCV-4) are all It is an electromagnetic pneumatic valve. A method of adsorbing a wafer using the vacuum adsorption system of claim 1, which includes: using the second pipeline (B) and the third pipeline (C) during the process of adsorbing and/or releasing the wafer. The gas from the gas source (400) is supplied to the adsorption pipeline inside the vacuum adsorption heater (200) to adjust the pressure difference between the back and front sides of the wafer, where the adsorption pipeline and the vent are (201) Fluid connectivity. The method of claim 9, wherein during the process of adsorbing the wafer, the second pipeline (B) and the third pipeline (C) are used to supply the gas from the gas source (400) to the adsorption tube. path, so that the pressure on the back side of the wafer is kept 30-150 Torr smaller than the pressure on the front side. If the method of claim 9 is used, the second pipeline (B) and the third pipeline (C) are used to supply the gas from the gas source (400) to the adsorption tube during the process of releasing the wafer. path, so that the pressure on the back side of the wafer is increased to greater than or equal to the pressure on the front side. The method of claim 9, wherein: during the process of releasing the wafer, the second pipeline (B) and the third pipeline (C) are used to supply gas from the gas source (400) to the adsorption pipeline to increase the pressure on the back side of the wafer to 5-10 Torr greater than the pressure on the front side. A method for adsorbing wafers using the vacuum adsorption system of claim 1, which includes the following steps: (a) Place the wafer: when the vacuum adsorption system is in a closed state, place the wafer on the bearing surface of the vacuum adsorption heater (200) in the reaction chamber (100); (b) Adsorb the wafer: start the vacuum adsorption system, continuously suck the gas in the adsorption pipeline inside the vacuum adsorption heater (200) through the second pipeline (B), so that the wafer The pressure on the back side is kept smaller than the pressure on the front side, thereby adsorbing the wafer on the bearing surface of the vacuum adsorption heater (200), wherein the adsorption pipeline is in fluid communication with the vent (201); and (c) Release the wafer: After processing the wafer, stop sucking the gas in the adsorption pipeline inside the vacuum adsorption heater (200), and use the second pipeline (B) and The third pipeline (C) supplies gas from the gas source (400) to the adsorption pipeline, so that the pressure on the back side of the wafer is increased to be equal to or greater than the pressure on the front side of the wafer to release the wafer. . The method of claim 13 further includes at least one of the following steps: (a1) Before step (a), heat the bearing surface of the vacuum adsorption heater (200), and pump the reaction chamber (100) to a vacuum state by the vacuum pump (300); and (a2) After step (a) and before step (b), inject gas into the reaction chamber (100) to increase the gas pressure (Pc) in the reaction chamber (100). Such as the method of request item 14, wherein: In step (a2), when the air pressure (Pc) in the reaction chamber (100) rises to exceed the threshold value, step (b) is started. Such as the method of claim 15, wherein the threshold value is 100 Torr. Such as the method of request item 13, wherein: In step (b), while using the vacuum pump (300) to continuously suck the gas in the adsorption pipeline in the vacuum adsorption heater (200) through the second pipeline (B), The second pipeline (B) and the third pipeline (C) supply gas from the gas source (400) into the adsorption pipeline, thereby maintaining the pressure on the back side of the wafer higher than the pressure on the front side of the wafer. Small 30-150 Torr. Such as the method of request item 13, wherein: A throttle valve (TV) is installed on the first pipeline (A); A first valve (CHCV-1) is installed on the second pipeline (B) near the vent (201); The third pipeline (C) is connected to the downstream of the first valve (CHCV-1) on the second pipeline (B), and a second valve (CHCV-1) is installed on the third pipeline (C) 2); The second pipeline (B) branches into a first manifold pipeline (B1) and a second manifold pipeline (B2) downstream of the first valve (CHCV-1); The other end of the first manifold (B1) is connected to the first pipeline (A) between the air extraction port (101) of the reaction chamber (100) and the throttle valve (TV). Three valves (CHCV-3) are placed on the first manifold (B1); and The other end of the second manifold (B2) is connected to the vacuum pump (300), and a fourth valve (CHCV-4) is disposed on the second manifold (B2). Such as the method of request item 18, wherein: During the execution of step (a), the first valve (CHCV-1), the second valve (CHCV-2), the third valve (CHCV-3) and the fourth valve (CHCV-4) are all closed, The throttle valve (TV) opens. Such as the method of request item 18, wherein: During the execution of step (b), the first valve (CHCV-1), the second valve (CHCV-2) and the fourth valve (CHCV-4) are all open, and the third valve (CHCV-3) is closed . The method of claim 20, wherein in step (b), the flow rate of the gas in the third pipeline (C) is adjusted so that the pressure on the back side of the wafer remains 30-150 Torr smaller than the pressure on the front side of the wafer. Such as the method of request item 18, wherein: During the execution of step (c), the first valve (CHCV-1), the second valve (CHCV-2) and the third valve (CHCV-3) are all open, and the fourth valve (CHCV-4) is closed . The method of claim 22, wherein in step (c), the flow rate of the gas in the third pipeline (C) is adjusted so that the pressure on the back side of the wafer is increased to be equal to or greater than the pressure on the front side. The method of claim 23, wherein in step (c), the flow rate of the gas in the third pipeline (C) is adjusted so that the pressure on the back side of the wafer is increased to 5-10 times greater than the pressure on the front side of the wafer. Torr.