Wafer caching apparatus, method and vertical batch epitaxy process apparatus

Abstract

The application provides a wafer caching device, a method and a vertical batch epitaxy process device. The heating unit of the wafer caching device forms a vacuum in the temporary storage cavity before hydrogen passivation, can remove the atmosphere and impurities in the temporary storage cavity, avoids the surface of the wafer from being oxidized in the initial stage, heats the wafer to an initial temperature at the beginning of hydrogen passivation, dynamically maintains the temperature of the wafer between the initial temperature and a terminal temperature during hydrogen passivation, the gas input unit inputs a mixed gas of nitrogen and hydrogen into the temporary storage cavity during hydrogen passivation, the vacuum unit extracts the nitrogen and hydrogen in the temporary storage cavity during hydrogen passivation, and the pressure of the temporary storage cavity is maintained to be not lower than 100 torr in combination with the gas input unit, so that the surface of the wafer is hydrogen passivated, and the surface of the wafer is prevented from being oxidized during long-time waiting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor equipment, in particular to a wafer caching device and method, and a vertical batch epitaxy process equipment based on the wafer caching device. BACKGROUND

[0002] With the development of semiconductor technology towards 3D vertical structure same as Gate-All-Around (GAA) structure, in order to ensure the performance and reliability of the device, the importance of wafer interface control is gradually rising.

[0003] In order to maximize the production efficiency and equipment utilization, a cluster system of single wafer type equipment for oxide removal (COR) process and batch epitaxy process equipment began to appear. In the cluster system, because the epitaxy process of the batch epitaxy process equipment is very long, the wafer processed in the single wafer type equipment for oxide removal process will wait for a long time in the buffer stocker before being loaded into the batch epitaxy process equipment.

[0004] In the prior art, the buffer stocker avoids the re-formation of fine natural oxide film on the surface of the wafer or the occurrence of organic contamination by high vacuum or nitrogen purge, but during the long waiting process, the wafer surface that has removed the surface oxide layer may still re-form fine natural oxide layer or occur organic contamination.

[0005] Therefore, it is necessary to provide a new wafer caching device, vertical batch epitaxy process equipment and wafer caching method to solve the above problems existing in the prior art. SUMMARY

[0006] The purpose of the present application is to provide a wafer caching device, wafer caching method and vertical batch epitaxy process equipment, which can effectively avoid the re-oxidation and / or contamination of the wafer surface that has removed the surface oxide layer by etching or other processes during the long waiting process for epitaxy process.

[0007] To achieve the above purpose, the wafer caching device of the present application is used to temporarily store wafers that have completed oxide removal process and are waiting for batch epitaxy process, and the wafer caching device comprises:

[0008] A cavity wall surrounds the temporary storage cavity;

[0009] A carrying unit is arranged in the temporary storage cavity and is used to carry a plurality of wafers, wherein the wafers are wafers with removed surface oxide layer;

[0010] a gas input unit, in communication with the temporary storage cavity, for inputting a mixed gas of nitrogen and hydrogen into the temporary storage cavity during hydrogen passivation;

[0011] a vacuum unit, in communication with the temporary storage cavity, for forming a vacuum in the temporary storage cavity before hydrogen passivation, and for extracting nitrogen and hydrogen in the temporary storage cavity during hydrogen passivation, and in combination with the gas input unit, maintaining the pressure of the temporary storage cavity to be not less than 100 torr;

[0012] a heating unit, disposed on the cavity wall, for heating the wafer to an initial temperature at the beginning of hydrogen passivation, and for dynamically maintaining the temperature of the wafer between the initial temperature and a terminal temperature higher than the initial temperature during hydrogen passivation, both the initial temperature and the terminal temperature being higher than the oxide removal process temperature and lower than the batch epitaxy process temperature.

[0013] Optionally, the hydrogen volume ratio of the mixed gas is 5% to 15%; the vacuum unit forms a vacuum with a pressure of 1mtorr-100mtorr in the temporary storage cavity before hydrogen passivation, and maintains the pressure of the temporary storage cavity to be 100-300 torr during hydrogen passivation; the initial temperature includes 97℃ to 103℃, and the terminal temperature includes 297℃ to 303℃.

[0014] Optionally, the wafer caching device further comprises an outer shell, the material of the outer shell has a thermal conductivity less than 1.4W / (m·k) and a melting point greater than 303℃, the outer shell is sleeved on the outside of the cavity wall, and a heating cavity is formed between the outer shell and the cavity wall.

[0015] The material of the cavity wall has a thermal conductivity greater than 14W / (m·k) and a melting point greater than 303℃, the heating unit comprises a plurality of independently controlled heating modules, the heating modules are dispersedly arranged in the heating cavity and connected with the outer side of the cavity wall.

[0016] The bearing unit comprises N bearing plates, N is a natural number greater than 1, the material of the bearing plate has a thermal conductivity less than 1.4W / (m·k) and a melting point greater than 303℃, and a plurality of the bearing plates are fixedly arranged on the inner side of the cavity wall.

[0017] The heat of the heating unit is transferred to the cavity wall and to a plurality of the wafers by heat radiation.

[0018] In an optional solution, the N bearing plates are arranged in a single column and arranged on the cavity wall in a direction perpendicular to the horizontal plane.

[0019] The gas input unit comprises a main pipeline, a plurality of auxiliary pipelines, a plurality of flow valves and N groups of side gas nozzles, each group of the side gas nozzles is arranged on the inner side of the cavity wall, the number of each group of the side gas nozzles is at least one, each group of the side gas nozzles corresponds to one of the bearing plates, each group of the side gas nozzles is located on the same horizontal plane, the horizontal plane where the nth group of the side gas nozzles from bottom to top is higher than the horizontal plane where the nth bearing plate from bottom to top, n is a natural number greater than or equal to 1 and less than or equal to N, the horizontal plane where the mth group of the side gas nozzles from bottom to top is lower than the horizontal plane where the m+1th bearing plate from bottom to top, m is a natural number greater than or equal to 1 and less than N, the number of the auxiliary pipelines and the number of the flow valves are the same as the number of the side gas nozzles, the flow valves are arranged on the corresponding auxiliary pipelines, one end of each of the auxiliary pipelines is communicated with the main pipeline, the other end of each of the auxiliary pipelines penetrates through the cavity wall and is communicated with the corresponding side gas nozzle, the center of the side gas nozzle is horizontally jetted and faces the middle part of the temporary storage cavity;

[0020] The flow valves adjust the gas flow in the corresponding auxiliary pipelines, so that the flow of the N groups of the side gas nozzles from top to bottom decreases in turn.

[0021] In another optional solution, the N bearing plates are arranged in a single column and are sequentially arranged on the cavity wall in a direction perpendicular to the horizontal plane.

[0022] The gas input unit comprises a main pipeline, N auxiliary pipelines, N flow valves and N top gas nozzles, each of the top gas nozzles corresponds to one of the bearing plates, the first top gas nozzle from top to bottom is arranged at the middle position of the top of the temporary storage cavity, the n+1th top gas nozzle from top to bottom is arranged at the middle of the lower bottom surface of the nth bearing plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N.

[0023] The flow valves are arranged on the corresponding auxiliary pipelines, one end of each of the N auxiliary pipelines is communicated with the main pipeline, the other end of each of the N auxiliary pipelines penetrates through the cavity wall and is communicated with the corresponding top gas nozzle.

[0024] The flow valves adjust the gas flow in the corresponding auxiliary pipelines, so that the flow of the N top gas nozzles from top to bottom decreases in turn.

[0025] In an optional solution, the N bearing plates are arranged in two columns, each of the bearing plates is sequentially arranged on the cavity wall in a direction perpendicular to the horizontal plane, and the two columns of bearing plates are alternately distributed on the height layer.

[0026] The gas input unit comprises a main pipeline, N sub-pipelines, N flow valves, a main gas nozzle, a main side gas nozzle and N-2 sub-gas nozzles, each of the sub-gas nozzles corresponds to one of the bearing plates, the main gas nozzle is arranged at the middle of the top of the temporary storage cavity and covers part of the top of the temporary storage cavity, the main side gas nozzle is arranged on the inner side of the cavity wall and the horizontal plane where the main side gas nozzle is located is higher than the horizontal plane where the first bearing plate from top to bottom is located, the nth sub-gas nozzle from top to bottom is arranged on the lower bottom surface of the n+1 bearing plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N-2, the center of the main gas nozzle is vertically and horizontally arranged, the center of the main side gas nozzle and the sub-gas nozzle is horizontally arranged and faces the middle of the temporary storage cavity.

[0027] The flow valves are arranged on the corresponding sub-pipelines, one end of each of the N sub-pipelines is in communication with the main pipeline, and the other end of each of the N sub-pipelines penetrates through the cavity wall and is in communication with the corresponding main gas nozzle, main side gas nozzle or sub-gas nozzle.

[0028] The flow valves adjust the gas flow in the corresponding sub-pipelines, the flow of the N-2 sub-gas nozzles from top to bottom decreases in turn, the flow of the first sub-gas nozzle from top to bottom is less than the flow of the main side gas nozzle, and the flow of the main side gas nozzle is less than the flow of the main gas nozzle.

[0029] In another optional solution, the N bearing plates are arranged in two columns, each of the bearing plates in each column is arranged on the cavity wall in the direction perpendicular to the horizontal plane in turn, and the bearing plates in the two columns are alternately distributed on the height layer.

[0030] The gas input unit comprises a main pipeline, N sub-pipelines, N flow valves, a main gas nozzle and N-2 sub-gas nozzles, each of the sub-gas nozzles corresponds to one of the bearing plates, the main gas nozzle is arranged on the top of the temporary storage cavity and covers the entire top of the temporary storage cavity, the nth sub-gas nozzle from top to bottom is arranged on the lower bottom surface of the n+1 bearing plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N-2, the center of the main gas nozzle is vertically and horizontally arranged, the center of the sub-gas nozzle is horizontally arranged and faces the middle of the temporary storage cavity.

[0031] The flow valves are arranged on the corresponding sub-pipelines, one end of each of the N sub-pipelines is in communication with the main pipeline, and the other end of each of the N sub-pipelines penetrates through the cavity wall and is in communication with the corresponding main gas nozzle or sub-gas nozzle.

[0032] The flow valve adjusts the gas flow in the sub-pipe, and the flow of the first sub-gas nozzle from top to bottom is less than the flow of the main gas nozzle.

[0033] Optionally, the wafer caching device further comprises a first online detection unit, a first detection hole is formed on the cavity wall at the top of the temporary storage cavity, and the first online detection unit is at least partially arranged in the first detection hole and used to detect whether an oxidation layer exists on the wafer surface.

[0034] Optionally, the wafer caching device further comprises N sliding mechanisms, the sliding mechanisms correspond to the bearing plates one by one, the sliding mechanisms are arranged between the bearing plates and the cavity wall, the positions of the bearing plates include an initial position and a detection position on the same horizontal plane, and the sliding mechanisms are used to drive the bearing plates to move between the initial position and the detection position.

[0035] In the above process, from bottom to top, the wafers are sequentially placed on the bearing plates, for the bearing plates that have carried the wafers, from bottom to top, the sliding mechanisms sequentially drive the corresponding bearing plates to move from the initial position to the detection position, after the bearing plates move to the detection position, the first online detection unit detects whether an oxidation layer exists on the surface of the corresponding wafer, after the detection is completed, the next sliding mechanism drives the corresponding bearing plate to move from the initial position to the detection position, and after the last sliding mechanism from bottom to top drives the corresponding bearing plate to move from the initial position to the detection position and the first online detection unit completes the detection, from top to bottom, the sliding mechanisms sequentially drive the corresponding bearing plates to move from the detection position to the initial position, after the bearing plates move to the initial position, the first online detection unit detects whether an oxidation layer exists on the surface of the corresponding wafer, and after the detection is completed, the next sliding mechanism drives the corresponding bearing plate to move from the detection position to the initial position.

[0036] Optionally, the gas input unit is further used to input epitaxial gas into the temporary storage cavity after the hydrogen passivation is completed, so as to form an initial epitaxial layer on the surfaces of the wafers.

[0037] The wafer caching device further comprises a second online detection unit, a second detection hole is formed on the cavity wall at the top of the temporary storage cavity, and the second online detection unit is at least partially arranged in the second detection hole and used to detect the quality of the initial epitaxial layer.

[0038] The application further provides a vertical batch epitaxy process equipment, which comprises a vertical epitaxy furnace body, a transfer cavity, a pretreatment cavity and the wafer buffer equipment according to any one of the preceding embodiments, the vertical epitaxy furnace body, the pretreatment cavity and the wafer buffer equipment are connected with the transfer cavity, a mechanical arm is arranged in the transfer cavity, used for transferring a wafer from outside to the pretreatment cavity for pretreatment, and transferring the wafer after pretreatment to the wafer buffer equipment, and transferring the wafer in the wafer buffer equipment to the vertical epitaxy furnace body for process treatment.

[0039] The application further provides a wafer buffering method using the wafer buffer equipment, which comprises:

[0040] The vacuum unit forms a vacuum in the temporary storage cavity before hydrogen passivation;

[0041] The heating unit heats the wafer to an initial temperature at the beginning of hydrogen passivation, and then enters the hydrogen passivation process;

[0042] During the hydrogen passivation process, the heating unit dynamically maintains the temperature of the wafer between the initial temperature and a terminal temperature higher than the initial temperature, both of which are higher than the oxide removal process temperature and lower than the batch epitaxy process temperature; at the same time, the gas input unit inputs a mixed gas of nitrogen and hydrogen into the temporary storage cavity, the vacuum unit extracts the nitrogen and hydrogen in the temporary storage cavity, and maintains the pressure of the temporary storage cavity not lower than 100 torr.

[0043] The application has the following beneficial effects: the heating unit forms a vacuum in the temporary storage cavity before hydrogen passivation, which can remove the atmosphere and impurities in the temporary storage cavity, and can avoid the oxidation of the surface of the wafer in the initial stage; the heating unit heats the wafer to an initial temperature at the beginning of hydrogen passivation; the heating unit dynamically maintains the temperature of the wafer between the initial temperature and a terminal temperature higher than the initial temperature during the hydrogen passivation process, so as to keep the surface of the wafer in good growth condition, which helps to improve the quality of subsequent epitaxial growth; the gas input unit inputs a mixed gas of nitrogen and hydrogen into the temporary storage cavity during hydrogen passivation, the vacuum unit extracts the nitrogen and hydrogen in the temporary storage cavity during hydrogen passivation, and in combination with the gas input unit, the pressure of the temporary storage cavity is maintained not lower than 100 torr, which can realize hydrogen passivation on the surface of the wafer, thereby protecting the surface of the wafer from being re-oxidized and / or contaminated. Moreover, since the surface of the wafer will not be oxidized, cleaning is not required or the required cleaning time is greatly shortened before subsequent epitaxy process, and since hydrogen passivation is performed during wafer storage, no additional time is occupied, which greatly shortens the overall process time and improves the overall process efficiency and equipment output rate. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 Fig. 1 is a schematic diagram of a wafer storage device according to a first embodiment of the present application;

[0045] Figure 2 Fig. 2 is a schematic diagram of a wafer storage device according to a second embodiment of the present application;

[0046] Figure 3 Fig. 3 is a schematic diagram of a wafer storage device according to a third embodiment of the present application;

[0047] Figure 4 Fig. 4 is a schematic diagram of a wafer storage device according to a fourth embodiment of the present application;

[0048] Figure 5 Fig. 5 is a schematic diagram of a wafer storage device according to an embodiment of the present application, in which a carrier plate is in an initial position;

[0049] Figure 6 Fig. 6 is a schematic diagram of a wafer storage device according to an embodiment of the present application, in which a carrier plate is in a detection position;

[0050] Figure 7 Fig. 7 is a schematic diagram of a wafer storage device according to an embodiment of the present application, in which a first on-line detection unit and a second on-line detection unit are arranged;

[0051] Figure 8 Fig. 8 is a schematic diagram of a wafer storage device according to an embodiment of the present application, in which a carrier plate is arranged;

[0052] Figure 9 Fig. 9 is a flow chart of a wafer storage method according to an embodiment of the present application.

[0053] 10, cavity wall; 101, vacuum hole; 102, first on-line detection unit; 103, first detection hole; 104, sliding mechanism; 105, second detection hole; 106, second on-line detection unit; 20, vacuum unit; 201, vacuum pipeline; 202, pressure controller; 203, vacuum pump; 30, heating unit; 40, temporary storage cavity; 50, outer housing; 60, heating cavity; 701, carrier plate; 7011, wafer taking port; 801, main pipeline; 802, auxiliary pipeline; 803, flow valve; 804, main gas nozzle; 805, side gas nozzle; 806, top gas nozzle; 807, auxiliary gas nozzle; 808, main side gas nozzle; 901, nitrogen gas inlet pipe; 902, hydrogen gas inlet pipe; 903, first gas flow controller; 904, second gas flow controller; 905, first gas valve; 906, second gas valve; 907, third gas valve; 908, fourth gas valve. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. Unless otherwise defined, the technical terms or scientific terms used herein should be understood as the common meanings by those of ordinary skill in the art to which the present application belongs. The terms such as "comprise" and the like used herein mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, without excluding other elements or objects.

[0055] In view of the problems in the prior art, the embodiments of the present application provide a wafer buffer device for temporarily storing wafers that have completed an oxide removal process and are waiting for batch epitaxy process processing. Therefore, the wafer buffer device is usually used with an oxide removal process device and a batch epitaxy process device, and the three are usually integrated on the same system.

[0056] The oxide removal process device is usually also called a pretreatment device or a pretreatment chamber, which, as the name implies, pretreats the wafer before formal process processing. Depending on the different pretreatment operations, the structure of the pretreatment device is also different. For example, in the present embodiment, the pretreatment device is a device for removing the natural oxide layer on the surface of the wafer, also known as an oxide removal process device, and therefore it can be a single wafer dry etching device, which can specifically include an etching chamber, a wafer carrier installed in the etching chamber, and an air inlet and exhaust system in communication with the etching chamber. In addition, it can also include a temperature control system for adjusting the temperature inside the etching chamber. In another example, the pretreatment device can also be a batch dry etching device, which is not strictly limited. The batch epitaxy process device is usually also called a vertical epitaxy furnace or vertical epitaxy furnace body, which, as the name implies, can simultaneously perform epitaxy process processing on several batches of wafers. Since the epitaxy process processing time can be as long as tens of hours, and the pretreatment time is usually within 30 minutes, the wafer that has been pretreated to remove impurities such as surface natural oxide layer and organic contaminants needs to be waited for a long time in the buffer device. However, the existing buffer device only relies on vacuum or nitrogen atmosphere to store the wafer, and the wafer has the risk of being contaminated again, which is difficult to meet the high cleanliness requirement of epitaxy process growth. Therefore, the present inventors have long-term research and propose an improvement scheme.

[0057] Specifically, with reference to Figures 1-4 The wafer buffer device provided by the present application includes a cavity wall 10, a vacuum unit 20, a heating unit 30, a gas input unit and a carrier unit.

[0058] With reference toFigures 1-4 The cavity wall 10 forms a closed temporary cavity 40 around. The carrier unit is arranged in the temporary cavity 40 for carrying a plurality of wafers, which are wafers with surface oxide layer removed, the oxide layer is usually a natural oxide layer formed on the wafer surface due to exposure to an oxygen-containing environment. For example, the wafer is a silicon wafer, and the surface oxide layer is silicon oxide; if it is a germanium wafer, the surface oxide layer is germanium oxide. The gas input unit is in communication with the temporary cavity 40 for introducing a mixed gas of nitrogen and hydrogen into the temporary cavity 40 during hydrogen passivation. The volume percentage of hydrogen in the mixed gas is much smaller than that of nitrogen, for example, the volume percentage of hydrogen is less than 25% of the nitrogen content, so as to meet the process requirements of hydrogen passivation while minimizing the hydrogen content to improve equipment safety. Preferably, the volume percentage of hydrogen in the mixed gas is 5% to 15%.

[0059] The vacuum unit 20 is in communication with the temporary cavity 40 for forming a vacuum in the temporary cavity 40 before hydrogen passivation, and the vacuum degree is preferably 1mtorr-100mtorr, which helps to exhaust the impurity gas in the temporary cavity. The vacuum unit 20 also extracts nitrogen and hydrogen in the temporary cavity 40 during hydrogen passivation, and in combination with the gas input unit, maintains the pressure of the temporary cavity 40 to be not less than 100torr, for example, 100-300torr. The heating unit 30 is arranged on the cavity wall 10 for heating the wafer to an initial temperature at the beginning of hydrogen passivation, and dynamically maintaining the temperature of the wafer between the initial temperature and an end temperature higher than the initial temperature during hydrogen passivation, for example, heating the wafer from the initial temperature to the end temperature, then stopping heating, and after the wafer falls back to the initial temperature, heating the wafer from the initial temperature to the end temperature again, and so on. The initial temperature and the end temperature are both higher than the oxide removal process temperature and lower than the batch epitaxial process temperature. That is, the temperature during hydrogen passivation is not constant but varies between the initial temperature and the end temperature, which can be regular or irregular, the important thing is to maintain the wafer temperature in this interval but not fixed at a specific temperature for a long time. By dynamically adjusting the temperature to maintain the wafer between the initial temperature and the end temperature, it helps to improve the interface / surface properties of the wafer and improve the quality of subsequent epitaxial growth. In a preferred example, the initial temperature is 97°C to 103°C, and the best is 100°C, and the end temperature is 297°C to 303°C, and the best is 300°C. This temperature interval helps to improve the effect and efficiency of hydrogen passivation treatment, while avoiding heat accumulation of the wafer.

[0060] In the present application, the vacuum unit 20 forms a vacuum with a pressure of 1-100 mtorr in the temporary storage cavity 40 before hydrogen passivation, which can remove the atmosphere and impurities in the temporary storage cavity 40 and avoid the oxidation of the wafer surface in the initial stage. In some examples, the vacuum degree in the temporary storage cavity 40 can also be dynamically changed within the above range before hydrogen passivation, which, combined with the dynamic adjustment of the temperature, helps to ensure that the gas remaining on the wafer surface during the previous pretreatment process is completely discharged, further improving the wafer surface quality. The heating unit 30 heats the wafer to an initial temperature at the beginning of hydrogen passivation. The heating unit 30 heats the wafer from the initial temperature to the end temperature during hydrogen passivation, and then stops heating. After the wafer falls back to the initial temperature, the wafer is heated again from the initial temperature to the end temperature. The gas input unit inputs a mixed gas of nitrogen and hydrogen with a hydrogen volume ratio of 5-15% into the temporary storage cavity 40 during hydrogen passivation. The vacuum unit 20 extracts nitrogen and hydrogen from the temporary storage cavity 40 during hydrogen passivation and maintains the pressure of the temporary storage cavity 40 at 100-300 torr in combination with the gas input unit, which can achieve hydrogen passivation on the surface of the wafer, thereby protecting the surface of the wafer and avoiding the surface of the wafer from being oxidized and / or contaminated again. Moreover, since the surface of the wafer will not be oxidized, cleaning is not required or only a very short time of cleaning is required before the subsequent epitaxial process, and since hydrogen passivation is performed during wafer storage, no additional time is occupied, which greatly shortens the overall process time and improves the overall process efficiency and equipment output rate. Hydrogen passivation is performed using the initial temperature to the end temperature, without the need for a plasma device for cleaning, which greatly reduces the cost, and the use of the temperature varying from the initial temperature to the end temperature helps to further optimize the properties of the wafer surface. The initial temperature includes 97-103℃, and the end temperature includes 297-303℃. The initial temperature and the end temperature are both lower than the temperature required for epitaxial process in the subsequent batch-type epitaxial process equipment, which can avoid heat accumulation of the wafer and improve the wafer stress condition, while reducing the temperature rising and falling time.

[0061] With reference to Figures 1-4 , the gas input unit is further configured to input nitrogen into the temporary storage cavity 40 after hydrogen passivation is completed and the temperature in the temporary storage cavity 40 falls to room temperature, so as to remove the residual hydrogen in the temporary storage cavity 40. The vacuum unit 20 is further configured to extract nitrogen and hydrogen from the temporary storage cavity 40 after hydrogen passivation is completed, in combination with the nitrogen input by the gas input unit, so as to remove the hydrogen in the temporary storage cavity 40 and return the pressure in the temporary storage cavity 40 to atmospheric pressure. After hydrogen passivation is completed, the gas input unit inputs nitrogen into the temporary storage cavity 40, in combination with the vacuum unit 20, which can discharge the hydrogen in the temporary storage cavity 40, avoid hydrogen leakage, and return the pressure in the temporary storage cavity 40 to atmospheric pressure, which greatly ensures safety.

[0062] In some embodiments, the wafer temporary storage cavity is provided with a hydrogen concentration detection unit for detecting the hydrogen concentration in the wafer temporary storage cavity, for example, detecting whether there is residual hydrogen in the temporary storage cavity 40 after the hydrogen passivation is completed. The hydrogen concentration detection unit includes a high-temperature catalytic combustion type hydrogen sensor or a high-temperature semiconductor type hydrogen sensor.

[0063] In some embodiments, the hydrogen passivation time is 10-60 minutes, preferably 30 minutes, but is specifically dependent on the process requirement and is not strictly limited.

[0064] In some embodiments, when the temporary storage cavity is full of wafers, the vacuum unit 20 forms a vacuum in the temporary storage cavity with a pressure of 1-100 mtorr, and then starts the hydrogen passivation. Taking the number of the carrier plates as 25 for example, when the temporary storage cavity stores 25 wafers, it means that the temporary storage cavity is full of wafers.

[0065] In some embodiments, the gas input unit is also used to input nitrogen into the temporary storage cavity after the vacuum unit forms a vacuum in the temporary storage cavity with a pressure of 1-100 mtorr, so that the pressure in the temporary storage cavity is 100-300 torr or atmospheric pressure. This can reduce the amount of hydrogen used, reduce production cost, facilitate subsequent wafer transfer operation, and avoid external gas backflow into the temporary storage cavity 40 when the temporary storage cavity is suddenly opened.

[0066] In some embodiments, the wafer caching device further comprises an outer shell 50 made of a material with a thermal conductivity less than 1.4 W / (m·k) and a melting point greater than 303℃, the outer shell 50 is sleeved on the outer side of the cavity wall 10 to form a heating cavity 60 with the cavity wall 10; the cavity wall 10 is made of a material with a thermal conductivity greater than 14 W / (m·k) and a melting point greater than 303℃, the heating unit 30 comprises a plurality of independently controlled heating modules, the heating modules are dispersedly arranged in the heating cavity 60 and connected with the outer side of the cavity wall 10; the heating unit 30 further comprises a temperature sensor and a PID control system, the temperature sensor is arranged on the cavity wall for detecting the temperature of the wafer or the temporary storage cavity 40, the PID control system is electrically connected with the temperature sensor and the heating modules, the PID control system detects the temperature of the wafer or the temporary storage cavity through the temperature sensor, and then drives the heating modules to heat the wafer; the bearing unit comprises N bearing plates 701, N is a natural number greater than 1, the bearing plate 701 is made of a material with a thermal conductivity less than 1.4 W / (m·k) and a melting point greater than 303℃, and a plurality of bearing plates 701 are fixedly arranged on the inner side of the cavity wall 10; wherein, the heat of the heating unit 30 is transferred to the cavity wall 10 and is transferred to a plurality of wafers by heat radiation. The heating module comprises a resistance heater and the like, and the temperature sensor comprises an infrared temperature sensor, a thermocouple temperature sensor, a thermal resistance temperature sensor, a thermistor temperature sensor and the like. A plurality of independently controlled heating modules can adjust the local temperature, thereby avoiding excessive local temperature and greatly reducing the temperature difference inside the temporary storage cavity.

[0067] In some embodiments, the material of the outer shell 50 comprises silica aerogel, alumina porous ceramic, aluminum silicate refractory fiber cotton and the like, the material of the cavity wall comprises stainless steel (for example, stainless steel of STS 316L type), and the inner surface of the cavity wall 10 can be formed with the same plating layer as the bearing plate 701 to further reduce the risk of wafer contamination. The material of the bearing plate 701 can be the same as the material of the wafer boat in the subsequent epitaxial equipment, for example, can be made of but not limited to quartz, silicon and the like. The outer shell 50 is made of a material with a thermal conductivity less than 1.4 W / (m·k) and a melting point greater than 303℃, such as silica aerogel, alumina porous ceramic, aluminum silicate refractory fiber cotton and the like, which can avoid heat overflow of the heating unit, avoid heat loss, improve the responsiveness of temperature control, keep the temperature more uniform, and at the same time can play a role in protecting the workers and avoiding high temperature scalding.

[0068] In a specific embodiment, the material of the cavity wall 10 is stainless steel, the material of the bearing plate 701 is quartz, the heat of the heating unit 30 is transferred to the cavity wall 10, and then radiated to the temporary storage cavity 40 through the cavity wall 10, and then transferred to the wafer. Non-contact heating is adopted, which can avoid the pollution and physical damage of the wafer, and can improve the uniformity of the wafer surface temperature, and the temperature is more controllable.

[0069] In some embodiments, the volume ratio of hydrogen in the mixed gas is 10%, the volume ratio of nitrogen is 90%, the initial temperature is 100℃, and the terminal temperature is 300℃.

[0070] In yet other embodiments, the volume ratio of hydrogen in the mixed gas is 15%, the volume ratio of nitrogen is 85%, the initial temperature is 97℃, and the terminal temperature is 297℃.

[0071] In other embodiments, the volume ratio of hydrogen in the mixed gas is 5%, the volume ratio of nitrogen is 95%, the initial temperature is 103℃, and the terminal temperature is 303℃.

[0072] In some embodiments, the flow rate of the mixed gas is 1slm-10slm, for example 1slm, 5slm or 10slm or any value in this interval.

[0073] Referring to Figures 1-4 The outer shell 50 is sleeved outside the cavity wall 10, and a heating cavity 60 is formed between the cavity wall 10 and the outer shell 50. The heating unit 30 includes a plurality of independently controlled heating modules, which are dispersedly arranged in the heating cavity 60 and connected with the outer side of the cavity wall 10.

[0074] Referring to Figure 1In the first embodiment, the N supporting plates 701 are arranged in a single column and sequentially arranged on the cavity wall 10 in a direction perpendicular to the horizontal plane; the gas input unit comprises a main pipe 801, a plurality of sub-pipes 802, a plurality of flow valves 803 and N groups of side gas nozzles 805, each group of the side gas nozzles 805 is arranged on the inner side of the cavity wall 10, the number of each group of the side gas nozzles 805 is at least one, each group of the side gas nozzles 805 corresponds to one of the supporting plates 701, each group of the side gas nozzles 805 is located in the same horizontal plane, and the horizontal plane where the nth group of the side gas nozzles 805 from bottom to top is higher than the horizontal plane where the nth supporting plate 701 from bottom to top, n is a natural number greater than or equal to 1 and less than or equal to N, the horizontal plane where the mth group of the side gas nozzles 805 from bottom to top is lower than the horizontal plane where the m+1th supporting plate 701 from bottom to top, m is a natural number greater than or equal to 1 and less than N, the number of the sub-pipes 802 and the number of the flow valves 803 are the same as the number of the side gas nozzles 805, the flow valves 803 are arranged on the corresponding sub-pipes 802, one end of each of the plurality of sub-pipes 802 communicates with the main pipe 801, the other end of each of the plurality of sub-pipes 802 communicates with the corresponding side gas nozzle 805 through the cavity wall 10, the center of the side gas nozzle 805 sprays gas horizontally and towards the middle of the temporary storage cavity 40; wherein the flow valves 803 adjust the gas flow in the corresponding sub-pipes 802, so that the flow of the N groups of the side gas nozzles 805 from top to bottom decreases sequentially.

[0075] In some examples, the supporting plate 701 is a ring-shaped plate, that is, only supporting the edge of the wafer, which structure facilitates the mechanical arm to extend into the wafer below for wafer pick-and-place.

[0076] In another example, the supporting plate 701 is a flat plate, for example, a circular plate or a square plate, which structure can provide support to the entire surface of the wafer, providing support stability, and at the same time, the wafer surface stress can be adjusted by the supporting plate, thereby improving the wafer surface warpage. For example, the supporting plate 701 can be provided with a plurality of power-adjustable heaters to adjust the temperature of different areas according to the wafer surface warpage to improve the wafer thermal stress and achieve the purpose of adjusting the warpage. Or different areas of the supporting plate 701 can be provided with different adsorption holes to adjust the adsorption force of the adsorption holes in different areas according to the wafer surface warpage to improve the wafer surface.

[0077] In some embodiments, the number of each group of the side gas nozzles is 2, 3, 6, 9 or even more.

[0078] Reference Figure 1In the first embodiment, the first side gas jet 805 in the N groups of side gas jets 805 has a central jet direction of a1, a2, a3, etc., and the second side gas jet 805 in the N groups of side gas jets 805 has a central jet direction of a4, a5, a6, etc. The a1 direction mixed gas and the a4 direction mixed gas converge in the middle of the temporary storage cavity 40, then diffuse towards the d1 direction, and also diffuse towards the opposite direction of a1, the opposite direction of a4, the opposite direction of a2, the opposite direction of a5, the opposite direction of a3, and the opposite direction of a6, so that the surface of the wafer is more uniformly contacted with the mixed gas. The upper layer mixed gas diffuses to the lower layer, so that the concentration of the lower layer mixed gas is much higher than that of the upper layer mixed gas. The flow valve 803 adjusts the flow of the mixed gas in the corresponding sub-pipe 802, so that the flow of the mixed gas of the N groups of side gas jets 805 from top to bottom decreases in turn, so that the amount of mixed gas contacted by the surface of all wafers is close, and the uniformity of hydrogen passivation is better.

[0079] Referring to Figure 2 In the second embodiment, the N carrier plates 701 are arranged in a single column and are sequentially arranged on the cavity wall 10 in a direction perpendicular to the horizontal plane. The gas input unit includes a main pipe 801, N sub-pipes 802, N flow valves 803, and N top gas jets 806. Each top gas jet 806 corresponds to a carrier plate 701. The first top gas jet 806 from top to bottom is arranged at the middle position of the top of the temporary storage cavity 40. The n+1th top gas jet 806 from top to bottom is arranged at the middle of the lower bottom surface of the nth carrier plate 701 from top to bottom, where n is a natural number greater than or equal to 1 and less than or equal to N. The flow valve 803 is arranged on the corresponding sub-pipe 802. One end of each of the N sub-pipes 802 communicates with the main pipe 801, and the other end of each of the N sub-pipes 802 communicates with the corresponding top gas jet 806 through the cavity wall 10. The central jet direction of the top gas jet 806 is the a direction perpendicular to the horizontal plane. The flow valve 803 adjusts the flow of the gas in the corresponding sub-pipe 802, so that the flow of the N top gas jets 806 from top to bottom decreases in turn.

[0080] Referring to Figure 2In the second embodiment, the top gas nozzle 806 is the same size as the wafer. The top gas nozzle 806 uniformly sprays the mixed gas, making the mixed gas in contact with the wafer surface as uniform as possible, and the upper layer of mixed gas can diffuse to the lower layer, making the concentration of the mixed gas in the lower layer much higher than that in the upper layer. The flow valve 803 adjusts the flow rate of the mixed gas in the corresponding sub-pipe 802, so that the flow rate of the mixed gas in the N top gas nozzles 806 from top to bottom decreases sequentially, making the amount of mixed gas in contact with all wafers similar, and improving the uniformity of hydrogen passivation.

[0081] Reference Figure 3 In the third embodiment, the N support plates 701 are arranged in two columns, and each column of support plates 701 is sequentially disposed on the cavity wall 10 along a direction perpendicular to the horizontal plane, with the two columns of support plates 701 alternating in height. The gas input unit includes a main pipe 801, N secondary pipes 802, N flow valves 803, a main gas nozzle 804, a main side gas nozzle 808, and N-2 secondary gas nozzles 807, with each secondary gas nozzle 807 corresponding to one support plate 701. 01. The main gas nozzle 804 is located at the middle of the top of the temporary storage cavity 40, and the main gas nozzle 804 covers part of the top of the temporary storage cavity 40. The main side gas nozzle 808 is located on the inner side of the cavity wall 10, and the horizontal plane of the main side gas nozzle 808 is higher than the horizontal plane of the first support plate 701 from top to bottom. The nth auxiliary gas nozzle 807 from top to bottom is located on the bottom surface of the (n+1)th support plate 701 from top to bottom, where n is a large number. The gas flow direction at the center of the main gas nozzle 804 is perpendicular to the horizontal plane, and the gas flow direction at the center of the main side gas nozzle 808 and the auxiliary gas nozzle 807 is horizontal and faces the middle of the temporary storage cavity 40. The flow valve 803 is disposed on the corresponding auxiliary pipe 802. One end of each of the N auxiliary pipes 802 is connected to the main pipe 801, and the other end of each of the N auxiliary pipes 802 passes through the cavity wall 1. 0 is connected to the corresponding main gas nozzle 804, the main side gas nozzle 808, or the auxiliary gas nozzle 807 respectively; wherein, the flow valve 803 adjusts the gas flow in the corresponding auxiliary pipe 802, so that the flow of the N-2 auxiliary gas nozzles 807 from top to bottom decreases sequentially, and the flow of the first auxiliary gas nozzle 807 from top to bottom is less than the flow of the main side gas nozzle 808, and the flow of the main side gas nozzle 808 is less than the flow of the main gas nozzle 804.

[0082] Reference Figure 3In the third embodiment, the center of the main gas nozzle 804 is in the a direction, the center of the main side gas nozzle 808 is in the b1 direction, and the center of the N-2 secondary gas nozzles 807 is in the c1, c2, b2, b3, and other directions. Since the main gas nozzle 804 is arranged in the middle of the top of the temporary storage cavity 40, the part of the wafer on the N supporting plates 701 close to the cavity wall 10 cannot contact the mixed gas sprayed by the main gas nozzle 804, but the mixed gas in the b1, c1, c2, b2, and b3 directions can compensate for this. Not only can it directly provide the mixed gas required for hydrogen passivation of the part of the wafer close to the cavity wall 10, but it can also change the direction of the mixed gas in the a direction. For example, the mixed gas in the b1 direction can change the mixed gas in the a direction to the d2 direction, the mixed gas in the c1 direction can change the mixed gas in the a direction to the d5 direction, the mixed gas in the b2 direction can change the mixed gas in the a direction to the d3 direction, the mixed gas in the c2 direction can change the mixed gas in the a direction to the d6 direction, and the mixed gas in the b3 direction can change the mixed gas in the a direction to the d4 direction, so that the surface of all wafers can contact the gas, improving the uniformity of the gas. The upper mixed gas will diffuse to the lower layer, so that the concentration of the lower mixed gas is much higher than that of the upper mixed gas. The flow valve 803 adjusts the gas flow in the corresponding secondary pipeline 802, so that the flow of the N-2 secondary gas nozzles 807 from top to bottom decreases in turn, and the flow of the first secondary gas nozzle 807 from top to bottom is less than that of the main side gas nozzle 808. The flow of the mixed gas of the main side gas nozzle 808 is less than that of the main gas nozzle 804, so that the amount of mixed gas contacted by all wafers is close, and the uniformity of hydrogen passivation is better.

[0083] Referring to Figure 4In the fourth embodiment, the N bearing plates 701 are arranged in two columns, each column of the bearing plates 701 is sequentially arranged on the cavity wall 10 in a direction perpendicular to the horizontal plane, and the two columns of the bearing plates 701 are alternately distributed on the height layer; the gas input unit comprises a main pipeline 801, N sub-pipelines 802, N flow valves 803, a main gas nozzle 804 and N-2 sub-gas nozzles 807, each of the sub-gas nozzles 807 corresponds to one of the bearing plates 701, the main gas nozzle 804 is arranged at the top of the temporary storage cavity 40, and the main gas nozzle 804 covers the entire top of the temporary storage cavity 40, the nth sub-gas nozzle 807 from top to bottom is arranged on the lower bottom surface of the nth+1 bearing plate 701 from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N-2, the center of the main gas nozzle 804 is in a direction perpendicular to the horizontal plane, the center of the sub-gas nozzle 807 is in a horizontal direction and faces the middle of the temporary storage cavity 40; the flow valve 803 is arranged on the corresponding sub-pipeline 802, one end of the N sub-pipelines 802 communicates with the main pipeline 801, and the other end of the N sub-pipelines 802 respectively communicates with the corresponding main gas nozzle 804 or sub-gas nozzle 807 through the cavity wall 10; wherein the flow valve 803 adjusts the gas flow in the corresponding sub-pipeline 802, so that the flow of the N-2 sub-gas nozzles 807 from top to bottom decreases in turn, and the flow of the first sub-gas nozzle 807 from top to bottom is less than the flow of the main gas nozzle 804.

[0084] Referring to Figure 4In the fourth embodiment, the center of the main gas nozzle 804 is in the a direction, and the center of the N-2 secondary gas nozzles 807 is in the c1 direction, the c2 direction, the b2 direction, the b3 direction, and the like. Since the main gas nozzle 804 is arranged on the top of the temporary storage cavity 40, and the main gas nozzle 804 covers the entire top of the temporary storage cavity 40, the surfaces of the wafers on the first two carrier plates 701 from top to bottom can be in contact with uniform gas, and the mixed gas in the c1 direction, the c2 direction, the b2 direction, and the b3 direction can play a compensating role. Not only can the mixed gas directly provide the mixed gas required by the hydrogen passivation of the wafers on the remaining N-2 carrier plates 701 close to the cavity wall 10, but also can change the direction of the mixed gas in the a direction, for example, the mixed gas in the c1 direction can change the mixed gas in the a direction to the d5 direction, the mixed gas in the b2 direction can change the mixed gas in the a direction to the d3 direction, the mixed gas in the c2 direction can change the mixed gas in the a direction to the d6 direction, and the mixed gas in the b3 direction can change the mixed gas in the a direction to the d4 direction, so that the surfaces of the wafers on the N-2 carrier plates 701 can be in contact with the gas, and the uniformity of the gas is improved. The upper layer gas diffuses to the lower layer, so that the concentration of the mixed gas in the lower layer is much higher than that in the upper layer. The flow valve 803 adjusts the flow of the mixed gas in the corresponding secondary pipeline 802, so that the flow of the mixed gas of the N-2 secondary gas nozzles 807 decreases in turn, and the flow of the mixed gas of the first secondary gas nozzle 807 from top to bottom is less than that of the main gas nozzle 804. The amount of mixed gas contacted by the wafers on all the carrier plates 701 is close, and the uniformity of hydrogen passivation is better.

[0085] Referring to Figures 1-4 , the vacuum unit 20 includes a vacuum pipeline 201, a pressure controller 202, and a vacuum pump 203. The cavity wall 10 is provided with a vacuum hole (exhaust hole) 101. One end of the vacuum pipeline 201 is in communication with the vacuum hole, and the other end of the vacuum pipeline 201 is connected with the vacuum pump 203. The pressure controller 202 is arranged on the vacuum pipeline 201. The pressure controller 202 is an automatic pressure controller.

[0086] Referring to Figures 1-4 , the main pipeline 801 is arranged in the heating cavity 60. The plurality of heating modules can preheat the gas in the main pipeline 801, so as to avoid the temperature change of the temporary storage cavity 40 when the low-temperature gas enters the temporary storage cavity 40, and ensure the relative stability of the temperature in the temporary storage cavity 40.

[0087] Referring to Figures 1-4The wafer caching device further comprises a nitrogen gas inlet pipe 901, a hydrogen gas inlet pipe 902, a first gas flow controller 903, a second gas flow controller 904, a first gas valve 905, a second gas valve 906, a third gas valve 907, and a fourth gas valve 908. One end of the nitrogen gas inlet pipe 901 and one end of the hydrogen gas inlet pipe 902 are in communication with the main pipe 801 through the outer housing 50. The other end of the nitrogen gas inlet pipe 901 is connected with a nitrogen gas supply device, and the other end of the hydrogen gas inlet pipe 902 is connected with a hydrogen gas supply device. The first gas valve 905, the first gas flow controller 903, and the second gas valve 906 are sequentially arranged in the nitrogen gas inlet pipe 901. The third gas valve 907, the second gas flow controller 904, and the fourth gas valve 908 are sequentially arranged in the hydrogen gas inlet pipe 902. The nitrogen gas supply device is a liquid nitrogen storage tank, and the hydrogen gas supply device is a liquid hydrogen storage tank.

[0088] With reference to Figure 5 、 Figure 6 and Figure 7 , the wafer caching device further comprises a first online detection unit 102. A first detection hole 103 is formed in the cavity wall 10 at the top of the temporary storage cavity. The first online detection unit 102 is at least partially arranged in the first detection hole 103, and is used to detect whether there is an oxidation layer on the wafer surface. The first online detection unit 102 comprises an ellipsometer.

[0089] With reference to Figure 5 、 Figure 6 and Figure 7The wafer caching device further comprises N sliding mechanisms 104 corresponding to the bearing plates 701, the sliding mechanisms 104 are arranged between the bearing plates 701 and the cavity wall 10, the positions of the bearing plates 701 include an initial position A and a detection position B on the same horizontal plane, and the sliding mechanisms 104 are used to drive the bearing plates 701 to move between the initial position A and the detection position B; wherein, from bottom to top, the wafers are sequentially placed on the bearing plates 701, for the bearing plates 701 that have carried the wafers, from bottom to top, the sliding mechanisms 104 sequentially drive the corresponding bearing plates 701 to move from the initial position A to the detection position B, after the bearing plates 701 move to the detection position B, the first online detection unit 102 detects whether there is an oxide layer on the surface of the corresponding wafer, after the detection is completed, the next sliding mechanism 104 drives the corresponding bearing plate 701 to move from the initial position A to the detection position B; after the last sliding mechanism 104 from bottom to top drives the corresponding bearing plate 701 to move from the initial position A to the detection position B, and the first online detection unit 102 completes the detection, from top to bottom, the sliding mechanisms 104 sequentially drive the corresponding bearing plates 701 to move from the detection position B to the initial position A, after the bearing plates 701 move to the initial position A, the first online detection unit 102 detects whether there is an oxide layer on the surface of the corresponding wafer, after the detection is completed, the next sliding mechanism 104 drives the corresponding bearing plate 701 to move from the detection position B to the initial position A.

[0090] In some embodiments, the sliding mechanism can adopt a structure of a sliding block, a sliding rail, a lead screw and a driving motor, or a structure of a sliding block, a sliding rail and a cylinder, or other structures capable of driving the bearing plate to move, which are not limited here.

[0091] Referring to Figure 5 , Figure 6 and Figure 7 , the gas input unit is further used to input epitaxial gas into the temporary storage cavity after the hydrogen passivation is completed, so as to form an initial epitaxial layer on the surfaces of the wafers; the wafer caching device further comprises a second online detection unit 106, a second detection hole 105 is arranged on the cavity wall 10 at the top of the temporary storage cavity, and the second online detection unit 106 is at least partially arranged in the second detection hole 105 and is used to detect the quality of the initial epitaxial layer, the second online detection unit 106 can adopt the same detection process as the first online detection unit 102 when detecting whether there is an oxide layer on the surface of the wafer. The second online detection unit 106 can comprise an X-ray diffractometer, an ellipsometer, etc.

[0092] In some embodiments, when the first on-line detection unit is an ellipsometer, the first on-line detection unit can realize multiplexing of functions, i.e., can detect whether there is an oxide layer on the wafer surface and can also detect the quality of the initial epitaxial layer. By detecting, through the first on-line detection unit 102, whether there is an oxide layer on the wafer surface, it can be detected whether the wafer surface is oxidized before hydrogen passivation, and the wafer with surface oxidation can be prevented from entering the subsequent batch epitaxial process equipment, thereby ensuring the quality of the subsequent epitaxial process. After the hydrogen passivation is completed, the gas input unit inputs epitaxial gas into the temporary storage cavity to form an initial epitaxial layer on the surface of a plurality of wafers, which can further prevent the surface of the wafer from being contaminated, and the quality of the wafer can be judged by detecting the quality of the initial epitaxial layer through the second on-line detection unit 106, thereby preventing the wafer with defects from entering the subsequent batch epitaxial process equipment and causing loss of equipment output.

[0093] In some embodiments, when the wafer is a silicon wafer, the epitaxial gas is a silicon source gas, such as disilane (Si2H6), and the concentration and time of the hydrogen gas input unit inputting the epitaxial gas can be adaptively adjusted, and a 0.1-2 mm silicon layer can be generated on the wafer surface.

[0094] Referring to Figures 1-8 In the case where the carrier plate 701 is a large-area flat plate, a wafer taking opening 7011 is formed in the middle of the carrier plate 701.

[0095] In some embodiments, the wafer caching device further comprises a hydrogen leakage detection unit arranged near the top of the temporary storage cavity and the hydrogen gas inlet pipe, for detecting whether hydrogen leaks and issuing an alarm when hydrogen leaks. The hydrogen leakage detection unit comprises an electrochemical hydrogen sensor, a catalytic combustion type hydrogen sensor, a thermal conductivity type hydrogen sensor, an optical type hydrogen sensor, etc.

[0096] In some embodiments, a wafer inlet and outlet communicating with the temporary storage cavity is formed on the cavity wall, the wafer inlet and outlet communicates with the transfer cavity, and a gate valve is arranged in the wafer inlet and outlet for controlling the communication and shutdown of the temporary storage cavity and the transfer cavity.

[0097] The present application also provides a wafer caching method using the wafer caching device, and the foregoing description of the wafer temporary storage device can be fully quoted here, and will not be described in detail for the sake of brevity. Referring to Figure 9 , the wafer caching method comprises the following steps:

[0098] S1: The vacuum unit forms a vacuum in the temporary storage cavity before hydrogen passivation;

[0099] S2: the heating unit heats the wafer to an initial temperature at the beginning of hydrogen passivation, and then enters the hydrogen passivation process;

[0100] S3: during the hydrogen passivation process, the heating unit dynamically maintains the temperature of the wafer between the initial temperature and an end temperature higher than the initial temperature, both of which are higher than the oxide removal process temperature and lower than the batch epitaxy process temperature; at the same time, the gas input unit inputs a mixed gas of nitrogen and hydrogen into the temporary storage cavity, and the vacuum unit extracts the nitrogen and hydrogen in the temporary storage cavity to maintain the pressure of the temporary storage cavity to be not less than 100 torr.

[0101] In a specific embodiment, the vacuum degree of the vacuum is preferably 1-100mtorr, the volume ratio of hydrogen in the mixture is 5-15%, the initial temperature includes 97-103℃, the end temperature includes 297-303℃, and the pressure of the temporary storage cavity is maintained to be 100-300torr during hydrogen passivation.

[0102] In some embodiments, the wafer caching method further comprises: after the hydrogen passivation is completed, the gas input unit inputs nitrogen into the temporary storage cavity, and the vacuum unit extracts the nitrogen and hydrogen in the temporary storage cavity to remove the residual hydrogen in the temporary storage cavity and return the pressure in the temporary storage cavity to atmospheric pressure.

[0103] In some embodiments, after step S1 is performed, the gas input unit further inputs nitrogen into the temporary storage cavity to make the pressure in the temporary storage cavity be 100-300torr or atmospheric pressure.

[0104] In some examples, after the hydrogen passivation process is completed, the temporary storage cavity is input with epitaxial gas to form an initial epitaxial layer on the wafer surface, then nitrogen is input to exhaust the residual epitaxial gas in the temporary storage cavity, and then the wafer is continuously maintained in a pure nitrogen atmosphere until it is transferred to an epitaxial device.

[0105] The present application also provides a vertical batch epitaxy process device, which comprises a vertical epitaxial furnace body, a transfer cavity, a pretreatment cavity and a wafer caching device as described in any of the above solutions. Therefore, the foregoing description of the wafer temporary storage device can be fully quoted here, and will not be described in detail for the purpose of brevity. Due to the use of the wafer caching device provided by the present application, the vertical batch epitaxy process device provided by the present application has multiple advantages such as improving epitaxial quality and increasing equipment output rate compared with the prior art.

[0106] The vertical epitaxial furnace body, the pretreatment cavity and the wafer buffer device are connected with the transfer cavity, a mechanical arm is arranged in the transfer cavity, used for transferring the wafer from outside to the pretreatment cavity for pretreatment, and transferring the wafer after the pretreatment to the wafer buffer device, and transferring the wafer in the wafer buffer device to the vertical epitaxial furnace body for process treatment; after the epitaxial treatment is completed, the wafer is transferred from the vertical epitaxial furnace body to the external device, or is first transferred to the wafer buffer device for temporary storage, and then is transferred to the external device. In this case, the wafer buffer device can be more than one, and multiple wafer buffer devices can be arranged at intervals on the same plane or stacked vertically.

[0107] The overall layout of the vertical batch epitaxial process equipment of the present application can be similar to the layout of the existing cluster tool. For example, a single or multiple pretreatment cavities are connected between the equipment front end module (EFEM) and the transfer cavity, and the wafer is transferred from outside to the pretreatment cavity through the equipment front end module for pretreatment. The pretreatment process includes but is not limited to removing the oxide on the surface of the wafer, especially the natural oxide layer and the organic contaminants and metal particles and other impurities on the surface, by dry etching. When there are more than two pretreatment cavities, different pretreatment cavities can be used for the same or different pretreatment, for example, one pretreatment cavity is used to remove the metal particles on the surface of the wafer, and then another pretreatment cavity is used to remove the oxide layer on the surface of the wafer. The vertical epitaxial furnace body, the pretreatment cavity and the wafer buffer device are arranged at intervals along the circumference of the transfer cavity. The transfer cavity includes a single or multiple mechanical arms for transferring the wafer between different cavities. In some examples, when there is only one wafer buffer device, the vertical batch epitaxial process equipment can also be additionally provided with a storage stack for temporarily storing the wafer after the epitaxial process treatment. The storage stack can store the wafer based on vacuum or nitrogen atmosphere. Because the subsequent process of the epitaxial process is usually etching or other processes with relatively low requirements for the cleanliness level of the wafer, using conventional storage methods instead of the wafer buffer device of the present application to store the wafer after the epitaxial process helps to reduce the cost of using the equipment. The specific structure of the vertical epitaxial furnace body, the pretreatment cavity and the transfer cavity in this embodiment is not limited, and therefore will not be expanded in detail.

[0108] The vertical batch epitaxial process equipment of the present application can be used for various epitaxial processes such as silicon epitaxy, germanium epitaxy, silicon carbide epitaxy, and can be used not only for homoepitaxy but also for heteroepitaxy, not only for pure epitaxy but also for doped epitaxy. The higher the requirement for epitaxial quality, the more prominent the advantages of using the vertical batch epitaxial process equipment of the present application.

[0109] While the embodiments of the application have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications and changes can be made to the embodiments without departing from the scope and spirit of the application, as described in the claims. Moreover, the application described is not limited in its application to the details set forth in the description or illustrated in the drawings. The application is capable of other embodiments and of being practiced or carried out in various ways.

Claims

1. A wafer caching device for temporarily storing wafers that have completed oxide removal processes and are awaiting batch epitaxial processing, characterized in that, The wafer caching device comprises: a cavity wall surrounding a temporary storage cavity; a bearing unit arranged in the temporary storage cavity for bearing a plurality of wafers, the wafers being wafers with removed surface oxide layers; a gas input unit in communication with the temporary storage cavity for inputting a mixed gas of nitrogen and hydrogen into the temporary storage cavity during hydrogen passivation; a vacuum unit in communication with the temporary storage cavity for forming a vacuum in the temporary storage cavity before hydrogen passivation, and for extracting nitrogen and hydrogen in the temporary storage cavity during hydrogen passivation, and in combination with the gas input unit, maintaining the pressure of the temporary storage cavity to be not less than 100 torr; a heating unit arranged on the cavity wall for heating the wafers to an initial temperature when hydrogen passivation starts, and dynamically maintaining the temperature of the wafers between the initial temperature and a terminal temperature higher than the initial temperature during hydrogen passivation, the initial temperature and the terminal temperature being both higher than the oxide removal process temperature and lower than the batch epitaxy process temperature.

2. The wafer buffer apparatus of claim 1, wherein, The hydrogen volume ratio of the mixed gas is 5% to 15%; the vacuum unit forms a vacuum with a pressure of 1mtorr-100mtorr in the temporary storage cavity before hydrogen passivation, and in combination with the gas input unit, maintains the pressure of the temporary storage cavity to be 100-300 torr during hydrogen passivation; the initial temperature is 97℃ to 103℃, and the terminal temperature is 297℃ to 303℃; The wafer caching device further comprises an outer shell, the outer shell is made of a material with a thermal conductivity less than 1.4W / (m·k) and a melting point greater than 303℃, the outer shell is sleeved on the cavity wall and forms a heating cavity with the cavity wall; The cavity wall is made of a material with a thermal conductivity greater than 14W / (m·k) and a melting point greater than 303℃, the heating unit comprises a plurality of independently controlled heating modules, the heating modules are dispersedly arranged in the heating cavity and connected with the outer side surface of the cavity wall; The bearing unit comprises N bearing plates, N is a natural number greater than 1, the bearing plates are made of a material with a thermal conductivity less than 1.4W / (m·k) and a melting point greater than 303℃, and a plurality of the bearing plates are fixedly arranged on the inner side surface of the cavity wall; The heat of the heating unit is transferred to the cavity wall and to a plurality of the wafers by heat radiation.

3. The wafer buffer apparatus of claim 2, wherein, The N bearing plates are arranged in a single column on the cavity wall in the direction perpendicular to the horizontal plane; The gas input unit comprises a main pipe, a plurality of sub-pipes, a plurality of flow valves and N groups of side gas nozzles, each group of the side gas nozzles is arranged on the inner side of the cavity wall, the number of each group of the side gas nozzles is at least one, each group of the side gas nozzles corresponds to one of the bearing plates, each group of the side gas nozzles is located in the same horizontal plane, and the horizontal plane where the nth group of the side gas nozzles from bottom to top is higher than the horizontal plane where the nth bearing plate from bottom to top, n is a natural number greater than or equal to 1 and less than or equal to N, the horizontal plane where the mth group of the side gas nozzles from bottom to top is lower than the horizontal plane where the m+1th bearing plate from bottom to top, m is a natural number greater than or equal to 1 and less than N, the number of the sub-pipes and the number of the flow valves are the same as the number of the side gas nozzles, the flow valves are arranged on the corresponding sub-pipes, one end of each of the plurality of sub-pipes is in communication with the main pipe, and the other end of each of the plurality of sub-pipes passes through the cavity wall and is in communication with the corresponding side gas nozzle, the center of the side gas nozzle is horizontally arranged, and the gas injection direction is towards the middle of the temporary storage cavity. The flow valves adjust the gas flow in the corresponding sub-pipes, so that the flow of the N groups of the side gas nozzles from top to bottom decreases in turn.

4. The wafer buffer apparatus of claim 2, wherein, The N bearing plates are arranged in a single column and are arranged in the vertical direction on the cavity wall in turn. The gas input unit comprises a main pipe, N sub-pipes, N flow valves and N top gas nozzles, each top gas nozzle corresponds to one of the bearing plates, the first top gas nozzle from top to bottom is arranged at the middle position of the top of the temporary storage cavity, and the n+1th top gas nozzle from top to bottom is arranged at the middle of the lower bottom surface of the nth bearing plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N. The flow valves are arranged on the corresponding sub-pipes, one end of each of the N sub-pipes is in communication with the main pipe, and the other end of each of the N sub-pipes passes through the cavity wall and is in communication with the corresponding top gas nozzle. The flow valves adjust the gas flow in the corresponding sub-pipes, so that the flow of the N top gas nozzles from top to bottom decreases in turn.

5. The wafer buffer apparatus of claim 2, wherein, The N bearing plates are arranged in two columns, each column of the bearing plates is arranged in the vertical direction on the cavity wall in turn, and the two columns of the bearing plates are alternately distributed in the height layer. The gas input unit comprises a main pipeline, N sub-pipelines, N flow valves, a main gas nozzle, a main side gas nozzle and N-2 sub-gas nozzles, each of the sub-gas nozzles corresponds to one of the carrier plates; the main gas nozzle is arranged at the middle of the top of the temporary storage cavity, and the main gas nozzle covers part of the top of the temporary storage cavity; the main side gas nozzle is arranged on the inner side of the cavity wall, and the horizontal plane where the main side gas nozzle is located is higher than the horizontal plane where the first carrier plate from top to bottom is located; the n-th sub-gas nozzle from top to bottom is arranged on the lower bottom surface of the n+1-th carrier plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N-2, the center of the main gas nozzle is vertically and horizontally arranged, the center of the main side gas nozzle and the sub-gas nozzle is horizontally arranged, and the center of the main side gas nozzle and the sub-gas nozzle is horizontally arranged towards the middle of the temporary storage cavity; The flow valve is arranged on the corresponding sub-pipeline, one end of each of the N sub-pipelines is in communication with the main pipeline, and the other end of each of the N sub-pipelines penetrates through the cavity wall and is in communication with the corresponding main gas nozzle, main side gas nozzle or sub-gas nozzle; Wherein, the flow valve adjusts the gas flow in the corresponding sub-pipeline, so that the flow of the N-2 sub-gas nozzles from top to bottom decreases in turn, and the flow of the first sub-gas nozzle from top to bottom is less than the flow of the main side gas nozzle, and the flow of the main side gas nozzle is less than the flow of the main gas nozzle; Or, the gas input unit comprises a main pipeline, N sub-pipelines, N flow valves, a main gas nozzle and N-2 sub-gas nozzles, each of the sub-gas nozzles corresponds to one of the carrier plates, the main gas nozzle is arranged on the top of the temporary storage cavity, and the main gas nozzle covers the entire top of the temporary storage cavity; the n-th sub-gas nozzle from top to bottom is arranged on the lower bottom surface of the n+1-th carrier plate from top to bottom, n is a natural number greater than or equal to 1 and less than or equal to N-2, the center of the main gas nozzle is vertically and horizontally arranged, the center of the main side gas nozzle and the sub-gas nozzle is horizontally arranged, and the center of the main side gas nozzle and the sub-gas nozzle is horizontally arranged towards the middle of the temporary storage cavity; The flow valve is arranged on the corresponding sub-pipeline, one end of each of the N sub-pipelines is in communication with the main pipeline, and the other end of each of the N sub-pipelines penetrates through the cavity wall and is in communication with the corresponding main gas nozzle or sub-gas nozzle; Wherein, the flow valve adjusts the gas flow in the corresponding sub-pipeline, so that the flow of the N-2 sub-gas nozzles from top to bottom decreases in turn, and the flow of the first sub-gas nozzle from top to bottom is less than the flow of the main gas nozzle.

6. The wafer buffer apparatus according to any one of claims 2 to 5, wherein Further comprising a first online detection unit, a first detection hole is formed in the cavity wall on the top of the temporary storage cavity, and the first online detection unit is at least partially arranged in the first detection hole and used for detecting whether there is an oxidation layer on the surface of the wafer.

7. The wafer buffer apparatus of claim 6, wherein, Further comprising N sliding mechanisms corresponding to the carrier plates, the sliding mechanisms being arranged between the carrier plates and the cavity wall, the positions of the carrier plates including an initial position and a detection position on the same horizontal plane, and the sliding mechanisms being used to drive the carrier plates to move between the initial position and the detection position; Wherein, from bottom to top, the wafers are sequentially placed on the carrier plates, and for the carrier plates that have carried the wafers, from bottom to top, the sliding mechanisms sequentially drive the corresponding carrier plates to move from the initial position to the detection position, after the carrier plates move to the detection position, the first online detection unit detects whether there is an oxide layer on the surface of the corresponding wafer, after the detection is completed, the next sliding mechanism drives the corresponding carrier plate to move from the initial position to the detection position; after the last sliding mechanism from bottom to top drives the corresponding carrier plate to move from the initial position to the detection position and the first online detection unit completes the detection, from top to bottom, the sliding mechanisms sequentially drive the corresponding carrier plates to move from the detection position to the initial position, after the carrier plates move to the initial position, the first online detection unit detects whether there is an oxide layer on the surface of the corresponding wafer, after the detection is completed, the next sliding mechanism drives the corresponding carrier plate to move from the detection position to the initial position.

8. The wafer buffer apparatus of claim 1, wherein, The gas input unit is further used to input epitaxial gas into the temporary storage cavity after the hydrogen passivation is completed, so as to form an initial epitaxial layer on the surface of the wafers. The wafer buffer device further comprises a second online detection unit, a second detection hole is formed on the cavity wall at the top of the temporary storage cavity, and the second online detection unit is at least partially arranged in the second detection hole and used to detect the quality of the initial epitaxial layer.

9. A vertical batch epitaxy process apparatus, characterized by, The vertical batch epitaxial process device comprises a vertical epitaxial furnace body, a transmission cavity, a pretreatment cavity and the wafer buffer device as claimed in any one of claims 1 to 8, the vertical epitaxial furnace body, the pretreatment cavity and the wafer buffer device are all connected with the transmission cavity, a mechanical arm is arranged in the transmission cavity and used to transmit wafers from outside to the pretreatment cavity for pretreatment, and transmit the wafers that have completed the pretreatment to the wafer buffer device and transmit the wafers in the wafer buffer device to the vertical epitaxial furnace body for process treatment.

10. A wafer caching method using the wafer caching apparatus according to any one of claims 1 to 8, characterized by, Comprise: The vacuum unit forms a vacuum in the temporary storage cavity before hydrogen passivation; The heating unit heats the wafers to an initial temperature at the beginning of hydrogen passivation, and then enters the hydrogen passivation process; During the hydrogen passivation process, the heating unit dynamically maintains the temperature of the wafers between the initial temperature and a terminal temperature higher than the initial temperature, both the initial temperature and the terminal temperature are higher than the oxide removal process temperature and lower than the batch epitaxial process temperature; at the same time, the gas input unit inputs a mixed gas of nitrogen and hydrogen into the temporary storage cavity, and the vacuum unit extracts nitrogen and hydrogen in the temporary storage cavity to maintain the pressure of the temporary storage cavity not lower than 100 torr.

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