Cleaning method and cleaning device for semiconductor structure

Abstract

The invention relates to a cleaning method and a cleaning device for a semiconductor structure. The cleaning method of the semiconductor structure comprises the following steps that the semiconductor structure is provided, and particles to be removed are attached to the surface of the semiconductor structure; executing the following circulation steps at least once: infiltrating the semiconductor structure into a first fluid so as to form a hydrophobic layer on the surface of the semiconductor structure; reducing the temperature of the first fluid to a first temperature, wherein the first temperature is lower than or equal to a freezing point of the first fluid; and raising the temperature of the first fluid covering the semiconductor structure so as to remove the particulate matters through the flowing of the first fluid. Damage to the semiconductor structure in the cleaning process is reduced, and the particulate matter removal effect is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technology, and in particular to a cleaning method and a cleaning device for a semiconductor structure. Background Art

[0002] Currently, the semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs, each with smaller and more complex circuits than the previous generation. In the course of IC development, functional density (i.e., the number of interconnected devices per chip area) has generally increased, while geometry size (i.e., the smallest component that can be produced using a manufacturing process) has decreased. In addition to IC components becoming smaller and more complex, the wafers on which ICs are manufactured have become larger and larger, which places increasingly higher demands on the quality of the wafers.

[0003] As the size of semiconductor structures such as dynamic random access memory (DRAM) continues to shrink, the size of particles remaining in the semiconductor structure also continues to shrink. The adhesion between particles and semiconductor structures is mainly van der Waals force, and the magnitude of van der Waals force increases significantly as the size of particles decreases, which makes it more difficult to remove particles. Currently, there is no effective method to effectively remove particles without damaging the semiconductor structure.

[0004] Therefore, how to improve the cleaning effect of semiconductor structures and reduce damage to semiconductor structures is a technical problem that needs to be solved urgently. Summary of the invention

[0005] Some embodiments of the present disclosure provide a cleaning method and a cleaning device for a semiconductor structure, which are used to improve the cleaning effect of the semiconductor structure and reduce damage to the semiconductor structure.

[0006] According to some embodiments, the present disclosure provides a method for cleaning a semiconductor structure, comprising the following steps:

[0007] Providing a semiconductor structure, the surface of which has particles to be removed;

[0008] Perform at least one of the following cycle steps, wherein the cycle steps include:

[0009] Immersing the semiconductor structure in a first fluid to form a hydrophobic layer on the surface of the semiconductor structure;

[0010] Lowering the temperature of the first fluid to a first temperature, the first temperature being lower than or equal to a freezing point of the first fluid;

[0011] The temperature of the first fluid covering the semiconductor structure is increased to remove the particles through the flow of the first fluid.

[0012] In some embodiments, the first fluid is heavy water.

[0013] In some embodiments, before immersing the semiconductor structure into the first fluid, the method further includes the following steps:

[0014] The semiconductor structure is cleaned using a chemical cleaning agent.

[0015] In some embodiments, the chemical cleaning agent is a mixed solution of heavy water and hydrofluoric acid, and the volume ratio of hydrofluoric acid to heavy water in the chemical cleaning agent is (1:30) to (1:300).

[0016] In some embodiments, the specific step of immersing the semiconductor structure into the first fluid includes:

[0017] The semiconductor structure is immersed in a first fluid for a preset time, wherein the preset time is 1 min to 20 min, and the first fluid at least soaks the particles.

[0018] In some embodiments, the specific step of immersing the semiconductor structure into the first fluid includes:

[0019] placing the semiconductor structure on a support table in a processing chamber;

[0020] The first fluid at a second temperature is continuously delivered to the semiconductor structure, and an auxiliary gas at a third temperature is delivered to the processing chamber, wherein the second temperature is higher than a freezing point of the first fluid, and the third temperature is lower than a freezing point of the first fluid.

[0021] In some embodiments, the second temperature ranges from 1°C to 10°C.

[0022] In some embodiments, the auxiliary gas is nitrogen or an inert gas, and the third temperature is lower than -70°C.

[0023] In some embodiments, the specific step of reducing the temperature of the first fluid to the first temperature includes:

[0024] The first fluid is stopped from being transmitted to the semiconductor structure, and the auxiliary gas at the third temperature is continuously transmitted to the processing chamber, so that the temperature of the first fluid remaining on the surface of the semiconductor structure is reduced to the first temperature.

[0025] In some embodiments, the specific step of reducing the temperature of the first fluid to the first temperature further includes:

[0026] The support table is rotated, and the rotation speed of the support table is controlled to decrease as the temperature of the first fluid decreases.

[0027] In some embodiments, the specific steps of increasing the temperature of the first fluid covering the semiconductor structure to remove the particles through the flow of the first fluid include:

[0028] A second fluid at a fourth temperature is transmitted to the semiconductor structure, and the support table is controlled to rotate, wherein the fourth temperature is higher than a freezing point of the first fluid.

[0029] In some embodiments, the second fluid is heavy water.

[0030] In some embodiments, the loop step is performed 1 to 10 times.

[0031] In some embodiments, after performing the cycle step at least once, the following steps are further included:

[0032] The semiconductor structure is dried.

[0033] According to some other embodiments, the present disclosure further provides a cleaning device for a semiconductor structure, which is used to clean a semiconductor structure using any of the cleaning methods for a semiconductor structure as shown above, including:

[0034] A processing chamber for accommodating a semiconductor structure to be cleaned, wherein particles to be removed are attached to a surface of the semiconductor structure;

[0035] a first transfer structure, used to transfer a first fluid to the processing chamber, wherein the first fluid is used to form a hydrophobic layer on the surface of the semiconductor structure;

[0036] a condenser, configured to reduce the temperature of the processing chamber so that the temperature of the first fluid in the processing chamber drops to a first temperature, wherein the first temperature is lower than or equal to a freezing point of the first fluid;

[0037] The second transfer structure is used to transfer a second fluid at a fourth temperature to the processing chamber, and to increase the temperature of the first fluid covering the semiconductor structure through the second fluid to remove the particles through the flow of the first fluid, wherein the fourth temperature is higher than the freezing point of the first fluid.

[0038] Some embodiments of the present disclosure provide a cleaning method and a cleaning device for a semiconductor structure, which lowers the temperature of a first fluid that wets the semiconductor structure to a first temperature, and limits the first temperature to be lower than or equal to the solidification point of the first fluid, so that the first fluid changes from a liquid state to a solid state, and then changes the first fluid from a solid state to a liquid state. On the one hand, the first fluid forms a hydrophobic layer on the surface of the semiconductor structure to reduce the adhesion between the particles to be removed and the semiconductor structure, thereby facilitating the removal of the particles; on the other hand, the particles are wrapped by the first fluid, and the volume expansion force generated when the first fluid solidifies is used to separate the particles, so that after the first fluid changes from a solid state to a liquid state, the particles can be removed by the flow of the first fluid. The cleaning method for a semiconductor structure provided by the present disclosure reduces damage to the semiconductor structure, improves the removal efficiency of particles, and improves the removal effect of particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Attached Figure 1 is a flow chart of a method for cleaning a semiconductor structure in a specific embodiment of the present disclosure;

[0040] Attached Figure 2 is a force analysis diagram of particles in a specific embodiment of the present disclosure;

[0041] Attached Figure 3 -Attached Figure 6 is a schematic diagram of a specific embodiment of the present disclosure during a process of cleaning a semiconductor structure;

[0042] Attached Figure 7 It is a schematic diagram of the structure of a cleaning device for a semiconductor structure in a specific embodiment of the present disclosure. DETAILED DESCRIPTION

[0043] The specific implementation of the semiconductor structure cleaning method and cleaning device provided by the present disclosure is described in detail below with reference to the accompanying drawings.

[0044] This specific embodiment provides a method for cleaning a semiconductor structure. Figure 1 is a flow chart of a method for cleaning a semiconductor structure in a specific embodiment of the present disclosure, Figure 2 is a force analysis diagram of particles in a specific embodiment of the present disclosure, Figure 3 -Attached Figure 6 FIG. 1 is a schematic diagram of a specific embodiment of the present disclosure during the process of cleaning a semiconductor structure. Figure 1-Figure 6 As shown, the cleaning method of the semiconductor structure comprises the following steps:

[0045] Step S11, providing a semiconductor structure 20, with particles 21 to be removed attached to the surface of the semiconductor structure 20;

[0046] Perform the following cycle steps at least once, the cycle steps comprising:

[0047] Step S12, immersing the semiconductor structure 21 into the first fluid 31 to form a hydrophobic layer on the surface of the semiconductor structure 20;

[0048] Step S13, lowering the temperature of the first fluid 31 to a first temperature, where the first temperature is lower than or equal to the freezing point of the first fluid 31;

[0049] In step S14 , the temperature of the first fluid 31 covering the semiconductor structure 20 is increased to remove particles through the flow of the first fluid 31 .

[0050] The semiconductor structure 20 in this specific embodiment can be but is not limited to DRAM. The material of the semiconductor structure 20 can be but is not limited to silicon. This specific embodiment is described by taking the material of the semiconductor structure 20 as silicon as an example. The semiconductor structure 20 may include an etching structure 30 formed by processes such as photolithography. In one example, the etching structure 30 is a groove with a high aspect ratio (for example, the aspect ratio is greater than or equal to 10). Byproducts or etchants from the formation of the etching structure 30 remain in the etching structure 30, and the residual byproducts or residual etchants serve as particles 21 to be removed. After the semiconductor structure 20 is immersed in the first fluid, the particles 21 in the semiconductor structure 20 are subjected to forces such as Figure 2 As shown, the particle 21 is subjected to buoyancy Fb, gravity Fg, drag force Fd, and adhesion force Fa. The drag force Fd of the first fluid on the particle 21 is Fd=d 2 ×V 2 , where d is the diameter of the particle, and V is the flow rate of the first fluid. The adhesion force Fa is mainly the van der Waals force, and thus the adhesion force Fa increases significantly as the size of the particle 21 decreases.

[0051] In some embodiments, before the semiconductor structure 20 is immersed in the first fluid, the following steps are further included:

[0052] The semiconductor structure 20 is cleaned using a chemical cleaning agent.

[0053] For example, after the etching structure 30 is formed by photolithography or other processes, the semiconductor structure may be cleaned by chemical cleaning agents, which can remove the chemical etchants and / or byproducts remaining in the photolithography or other processes through chemical reactions.

[0054] In some embodiments, the chemical cleaning agent is a mixed solution of heavy water (D2O) and hydrofluoric acid, and the volume ratio of hydrofluoric acid to heavy water in the chemical cleaning agent is V 氢氟酸 :V 重水 =(1:30)~(1:300), where V 重水Indicates the volume of heavy water in the chemical cleaning agent, V 氢氟酸 represents the volume of hydrofluoric acid in the chemical cleaning agent, where the hydrofluoric acid refers to hydrofluoric acid with a mass ratio of 49%. In one example, the volume ratio of heavy water to hydrofluoric acid in the chemical cleaning agent is V 氢氟酸 :V 重水 =1:30, V 氢氟酸 :V 重水 =1:50,V 氢氟酸 :V 重水 =1:100,V 氢氟酸 :V 重水 =1:200 or V 氢氟酸 :V 重水 =1:300.

[0055] For example, a mixed solution of heavy water and hydrofluoric acid is used to clean the semiconductor structure 20. On the one hand, the chemical etchant and / or byproducts remaining in the photolithography process can be removed by chemical reaction. On the other hand, after the semiconductor structure 20 is treated with the mixed solution of heavy water and hydrofluoric acid, a passivation layer can be formed on the surface of the semiconductor structure 20. For example, a Si-D (silicon-deuterium bond) bond with stronger hydrophobicity than Si-H bond is formed on the surface of the semiconductor structure, thereby enhancing the oxidation resistance of the semiconductor structure, effectively preventing the natural oxidation of the surface of the semiconductor structure 20, and ensuring the performance stability of the semiconductor structure 20. After the passivation layer is formed on the surface of the semiconductor structure 20 by treating the mixed solution of heavy water and hydrofluoric acid, since the semiconductor structure is isolated from oxygen in the external environment by the passivation layer, the semiconductor structure does not need to be vacuum stored, thereby simplifying the cleaning process of the semiconductor structure 20 and reducing the cleaning cost of the semiconductor structure 20. The stability of the passivation layer formed after treatment with heavy water (D2O) is higher than that of the passivation layer formed after treatment with water (H2O), and the contact angle of the deuterium (D) passivated surface is higher than that of the hydrogen (H) passivated surface, which is more conducive to maintaining the morphology of the pattern (for example, maintaining the morphology of the etching structure 30 in the semiconductor structure 20), thereby further ensuring the performance stability of the semiconductor structure 20.

[0056] In one example, after the semiconductor structure 20 is cleaned with a chemical cleaning agent, the semiconductor structure 20 may be soaked and rinsed with heavy water at room temperature, i.e., a soaking step is performed to remove residual hydrofluoric acid and reduce the residual hydrofluoric acid in the semiconductor structure 20. The room temperature may be 20° C. to 30° C. (e.g., 20° C., 25° C., or 30° C.).

[0057] In some embodiments, the first fluid is heavy water. Using heavy water as the first fluid, on the one hand, the heavy water can improve the hydrophobicity of the semiconductor structure 20, forming a stable hydrophobic layer on the surface of the semiconductor structure 20, thereby quickly and effectively reducing the adhesion between the particulate matter 21 and the semiconductor structure 20, and facilitating the subsequent removal of the particulate matter 21; on the other hand, the heavy water can be removed by drying and will not cause secondary contamination to the semiconductor structure 20, thereby helping to further simplify the cleaning process of the semiconductor structure 20.

[0058] In some embodiments, the specific steps of wetting the semiconductor structure 20 into the first fluid 31 include:

[0059] The semiconductor structure 20 is immersed in the first fluid 31 for a preset time, which is 1 min to 20 min, and the first fluid 31 at least wets the particles 21. In one example, the preset time is 1 min, 3 min, 5 min, 8 min, 10 min, 15 min or 20 min.

[0060] In some embodiments, the specific steps of wetting the semiconductor structure 20 into the first fluid 31 include:

[0061] Place the semiconductor structure 20 on the support table 61 of the processing chamber 60, such as Figure 6 As shown;

[0062] The first fluid 31 at the second temperature is continuously transmitted to the semiconductor structure 20, and the auxiliary gas at the third temperature is transmitted to the processing chamber 60, wherein the second temperature is higher than the freezing point of the first fluid 31, and the third temperature is lower than the freezing point of the first fluid 31. The freezing point of the first fluid 31 refers to the temperature at which the first fluid 31 changes from a liquid state to a solid state.

[0063] In some embodiments, the second temperature ranges from 1° C. to 10° C. In one example, the second temperature is 1° C., 3° ​​C., 5° C., 8° C., or 10° C.

[0064] In some embodiments, the auxiliary gas is nitrogen or an inert gas, and the third temperature is lower than -70° C. In one example, the auxiliary gas is nitrogen. The inert gas in this embodiment refers to a gas composed of elements of Group VIII in the periodic table.

[0065] The following description is made by taking the first fluid as heavy water as an example. For example, after the semiconductor structure 20 is placed in the processing chamber 60, the semiconductor structure is cleaned by a chemical cleaning agent, and the semiconductor structure 20 is soaked in the first fluid 31 for a preset time, a pre-cooling step is performed on the semiconductor structure 20. In the pre-cooling step, the first fluid 31 at the second temperature is continuously transmitted to the processing chamber 60 at a transmission speed of 100ml / min to 2000ml / min through the nozzle 62 extending into the processing chamber 60 and located above the support platform 61, and the auxiliary gas at the third temperature is continuously transmitted to the processing chamber 60 through the pipeline extending into the processing chamber 60 and located below the support platform 61. At the same time, the support platform 61 is driven at a first rotation speed, and the rotation of the support platform 61 drives the rotation of the semiconductor structure 20 located on the support platform 61, so that the first fluid 31 can soak the semiconductor structure 20. The auxiliary gas at the third temperature is used to cool the first fluid 31 at the second temperature, and the first fluid 31 reaches a saturated state at its freezing point. In one example, the first rotation speed is 500rpm to 1200rpm. The time for the first fluid 31 to infiltrate the semiconductor structure 20 is set within a preset time. On the one hand, it can avoid the problem that the time for the first fluid 31 to be introduced is too short and the semiconductor structure cannot be fully infiltrated. On the other hand, it can also avoid the problem that the time for introducing the first fluid 31 is too long and the fluid pressure generated by the excessive first fluid 31 causes damage to the etching structure in the semiconductor structure. The second temperature is set to 1°C to 10°C (for example, 5°C) and the third temperature is lower than -70°C, so that the temperature of the first fluid 31 can be lowered by auxiliary gas, so that the first fluid 31 is in a supercooled state, that is, the first fluid 31 is in a saturated state of solid-liquid mixture (that is, it reaches the solidification saturation point), so that the semiconductor structure 20 can be infiltrated by the first fluid 31 in a liquid state, and the first fluid 31 in a solid state (for example Figure 3 The ice particles 22) encapsulate the particles 21, such as Figure 3 As shown, it is more conducive to the subsequent removal of the residual particles 21 in the semiconductor structure 20.

[0066] While the first fluid 31 is transmitted to the processing chamber 60, an auxiliary gas having a temperature lower than that of the first fluid 31 is also transmitted to the processing chamber 60, so that the vapor (e.g., water vapor) of the first fluid 31 can be prevented from gathering above the support table 61 or inside the processing chamber 60, so that the semiconductor structure 20 can be fully infiltrated, and the cleaning effect of the semiconductor structure 20 can be further improved. The solidification saturation point of the first fluid is -70°C, but the auxiliary gas will be lost due to heat conduction during the transmission process, so in one example, the third temperature is -80°C to -180°C, such as -80°C, -90°C, -100°C, -110°C, -130°C, -150°C or -180°C, so as to ensure that the auxiliary gas can reduce the temperature of the first fluid 31 to its solidification saturation point.

[0067] In some embodiments, the specific steps of reducing the temperature of the first fluid 31 to the first temperature include:

[0068] The first fluid 31 is stopped from being delivered to the semiconductor structure 20 , and the auxiliary gas at the third temperature is continuously delivered to the processing chamber 60 , so that the temperature of the first fluid remaining on the surface of the semiconductor structure 20 is reduced to the first temperature.

[0069] For example, after the semiconductor structure 20 is immersed in the first fluid 31 in a saturated state for a predetermined time (i.e., the duration of the pre-cooling step), the first fluid 31 is stopped from being transmitted into the processing chamber 60, and the auxiliary gas at the third temperature is continuously transmitted into the processing chamber 60 to reduce the temperature of the processing chamber 60, so that the temperature of the processing chamber 60 is reduced to the first temperature, and the first fluid 31 is completely transformed from a liquid state to a solid state (i.e., heavy water freezes). When the first fluid 31 solidifies into a solid state, a volume expansion force is generated, and the volume expansion force separates the particles 21 previously wrapped by the ice particles 22 from the semiconductor structure 20, such as Figure 4 As shown, Figure 4 The arrow direction in the figure indicates the movement direction of the particles 21 under the action of the volume expansion force. By maintaining the state of continuously transmitting the auxiliary gas at the third temperature into the processing chamber 60, the accumulation of the vapor (such as water vapor) of the first fluid 31 above the support table 61 or inside the processing chamber 60 can be further avoided.

[0070] In order to further improve the cleaning effect of the semiconductor structure, in some embodiments, the specific step of lowering the temperature of the first fluid 31 to the first temperature further includes:

[0071] The support platform 61 is rotated and the rotation speed of the support platform 61 is controlled to decrease as the temperature of the first fluid 31 decreases. In the process of reducing the temperature of the first fluid 31 remaining on the surface of the semiconductor structure 20 to the first temperature, the rotation speed of the support platform 61 is a second rotation speed, which is lower than the first rotation speed. In one example, the second rotation speed is 5 rpm to 50 rpm, for example, the second rotation speed is 5 rpm, 10 rpm, 15 rpm, 20 rpm, 30 rpm or 50 rpm.

[0072] In one example, in the process of lowering the temperature of the first fluid 31, the temperature of the first fluid 31 or the temperature inside the processing chamber 60 can be monitored in real time. When the temperature of the first fluid 31 is higher than the threshold temperature, the rotation speed of the support table 61 is maintained at 50 rpm; when the temperature of the first fluid 31 is lower than or equal to the threshold temperature, the rotation speed of the support table 61 is maintained at 5 rpm, and the second rotation speed is lower than the first rotation speed; when the temperature of the first fluid 31 drops to the first temperature, the support table 61 stops rotating. The first temperature can be 0°C to -80°C, for example -40°C.

[0073] In some embodiments, the specific steps of increasing the temperature of the first fluid 31 covering the semiconductor structure 20 to remove particles through the flow of the first fluid 31 include:

[0074] The second fluid at a fourth temperature is transmitted to the semiconductor structure 20 , and the support platform 61 is controlled to rotate. The fourth temperature is higher than the freezing point of the first fluid 31 .

[0075] In some embodiments, the second fluid is heavy water.

[0076] For example, the second fluid at a fourth temperature can be transmitted to the semiconductor structure 20 in the processing chamber 60 through a nozzle located above the processing chamber 60 at a transmission speed of 100ml / min to 2000ml / min (for example, 100ml / min, 200ml / min, 300ml / min, 500ml / min, 1000ml / min, 1500ml / min or 2000ml / min). Since the fourth temperature is higher than the first temperature, the first fluid 31 can begin to melt through heat exchange between the second fluid at the fourth temperature and the first fluid 31 at the first temperature, that is, the first fluid 31 at least partially begins to change from a solid state to a liquid state. As the support table 61 rotates, the particles 21 leave the semiconductor structure 20 through the action of centrifugal force, the drag force of the second fluid, and the drag force of the first fluid, thereby achieving the removal of the particles 21, such as Figure 5 As shown, Figure 5The direction of the arrow in represents the movement direction of the particles 21 after the first fluid melts. In one example, the fourth temperature may be room temperature, such as 20°C to 30°C (eg, 20°C, 25°C or 30°C), to improve the melting efficiency of the first fluid 31 .

[0077] In some embodiments, the cycle step is performed 1 to 10 times to further improve the cleaning effect of the semiconductor structure. The cycle step includes steps S12 to S14. In one example, the cycle step is performed 1, 3, 5 or 8 times.

[0078] In some embodiments, after performing at least one cycle step, the method further comprises the following steps:

[0079] The semiconductor structure 20 is dried.

[0080] In one example, the semiconductor structure 20 can be dried by gas purging, for example, nitrogen is used to purge the semiconductor structure 20 to remove the residual heavy water in the semiconductor structure 20, so as to simplify the drying operation of the semiconductor structure. In another example, the semiconductor structure 20 can also be dried by IPA (isopropyl alcohol) to improve the drying effect of the semiconductor structure. In the process of drying the semiconductor structure 20, the rotation speed of the support table 61 is a third rotation speed, which is higher than the second rotation speed. In one example, the third rotation speed is 100rpm to 2500rpm, for example, the third rotation speed is 100rpm, 200rpm, 500rpm, 1000rpm, 1500rpm or 2500rpm.

[0081] This specific embodiment also provides a semiconductor structure cleaning device for using Figure 1 , Figure 3-Figure 6 The semiconductor structure cleaning method shown is used to clean the semiconductor structure. Figure 7 Schematic diagram of the cleaning device for semiconductor structure in a specific embodiment of the present disclosure. Figure 1 , Figure 3-Figure 7 As shown, a cleaning device for a semiconductor structure comprises:

[0082] The processing chamber 60 is used to accommodate the semiconductor structure 20 to be cleaned, and the surface of the semiconductor structure 20 has particles 21 to be removed;

[0083] A first transfer structure, used to transfer a first fluid 31 to the processing chamber 60, wherein the first fluid 31 is used to form a hydrophobic layer on the surface of the semiconductor structure 20;

[0084] The condenser 72 is used to reduce the temperature of the processing chamber 60 so that the temperature of the first fluid 31 in the processing chamber 60 is reduced to a first temperature, and the first temperature is lower than or equal to the freezing point of the first fluid 31;

[0085] The second transfer structure is used to transfer a second fluid at a fourth temperature to the processing chamber 60, and to increase the temperature of the first fluid 31 covering the semiconductor structure 20 through the second fluid to remove particulate matter through the flow of the first fluid 31, and the fourth temperature is higher than the freezing point of the first fluid 31.

[0086] The semiconductor structure 20 in this specific embodiment can be but is not limited to DRAM. The material of the semiconductor structure 20 can be but is not limited to silicon. This specific embodiment is described by taking the material of the semiconductor structure 20 as silicon as an example. The semiconductor structure 20 may include an etching structure 30 formed by processes such as photolithography. In one example, the etching structure 30 is a groove with a high aspect ratio (for example, the aspect ratio is greater than or equal to 10). Byproducts or etchants from the formation of the etching structure 30 remain in the etching structure 30, and the residual byproducts or residual etchants serve as particles 21 to be removed. After the semiconductor structure 20 is immersed in the first fluid, the particles 21 in the semiconductor structure 20 are subjected to forces such as Figure 2 As shown, the particle 21 is subjected to buoyancy Fb, gravity Fg, drag force Fd, and adhesion force Fa. The drag force Fd of the first fluid on the particle 21 is Fd=d 2 ×V 2 , where d is the diameter of the particle, and V is the flow rate of the first fluid. The adhesion force Fa is mainly the van der Waals force, and thus the adhesion force Fa increases significantly as the size of the particle 21 decreases.

[0087] For example, in the case of Figure 7 When the semiconductor structure cleaning device shown in the figure cleans the semiconductor structure 20, the semiconductor structure 20 is first placed on the support table 61 in the processing chamber 60. Afterwards, a chemical cleaning agent can be transmitted through the first pipeline 77 connected to the processing chamber 60 to use the chemical cleaning agent to clean the semiconductor structure 20. In some embodiments, the chemical cleaning agent is a mixed solution of heavy water (D2O) and hydrofluoric acid (HF with a mass ratio of 49%), and the volume ratio of heavy water to hydrofluoric acid in the chemical cleaning agent is V. 氢氟酸 :V 重水 =(1:30)~(1:300). In one example, the volume ratio of heavy water to hydrofluoric acid in the chemical cleaning agent is V 氢氟酸 :V 重水 =1:30, V 氢氟酸 :V 重水 =1:50,V 氢氟酸 :V 重水 =1:100,V 氢氟酸 :V 重水 =1:200 or V 氢氟酸 :V 重水=1:300. The remaining chemical cleaning agent inside the processing chamber 60 can be discharged from the processing chamber 60 through the drain cup 74 and the first discharge pipe 75 in sequence. The first transmission structure includes a second pipe 78 connected to the first pipe 77. The second pipe 78 is connected to a first storage source for storing a first fluid at a second temperature. The mixed solution of heavy water and hydrofluoric acid is used to clean the semiconductor structure 20. On the one hand, it can remove the chemical etchants and / or by-products and other residues remaining in the photolithography process through chemical reactions. On the other hand, after the semiconductor structure 20 is treated with the mixed solution of heavy water and hydrofluoric acid, a passivation layer can be formed on the surface of the semiconductor structure 20, thereby effectively preventing the natural oxidation of the surface of the semiconductor structure 20 and ensuring the performance stability of the semiconductor structure 20. After the passivation layer is formed on the surface of the semiconductor structure 20 by treating the mixed solution of heavy water and hydrofluoric acid, since the semiconductor structure is isolated from oxygen in the external environment by the passivation layer, it is no longer necessary to vacuum store the semiconductor structure, thereby simplifying the cleaning process of the semiconductor structure 20 and reducing the cleaning cost of the semiconductor structure 20. The stability of the passivation layer formed after treatment with heavy water (D2O) is higher than that of the passivation layer formed after treatment with water (H2O), and the contact angle of the deuterium (D) passivated surface is higher than that of the hydrogen (H) passivated surface, which is more conducive to maintaining the morphology of the pattern (for example, maintaining the morphology of the etching structure 30 in the semiconductor structure 20), thereby further ensuring the performance stability of the semiconductor structure 20.

[0088] After the semiconductor structure 20 is cleaned with a chemical cleaning agent, the semiconductor structure 20 may be soaked and rinsed with heavy water at room temperature, i.e., a soaking step is performed to remove residual hydrofluoric acid and reduce the residual hydrofluoric acid in the semiconductor structure 20. The room temperature may be 20° C. to 30° C. (e.g., 20° C., 25° C., or 30° C.).

[0089] After the infiltration step is performed, a pre-cooling step is performed. In the pre-cooling step, the first fluid 31 of the second temperature is continuously transmitted to the processing chamber 60 at a transmission speed of 100ml / min to 2000ml / min through the second pipe 78 and the first pipe 77 in turn, and the auxiliary gas of the third temperature is continuously transmitted to the processing chamber 60 through the third pipe 71 extending to the inside of the processing chamber 60 and located below the support table 61. Among them, one end of the third pipe 71 is connected to the gas source for storing the auxiliary gas, and the other end is connected to the processing chamber 60. While transmitting the first fluid 31 of the second temperature to the processing chamber 60, the support table 61 is driven to rotate at a first speed, and the rotation of the support table 61 drives the rotation of the semiconductor structure 20 located on the support table 61, so that the first fluid 31 can infiltrate the semiconductor structure. The auxiliary gas of the third temperature is used to cool the first fluid 31 of the second temperature, and the first fluid 31 reaches a saturated state at its freezing point. In one example, the first speed is 500rpm to 1200rpm. The auxiliary gas can prevent the vapor (such as water vapor) of the first fluid 31 from gathering above the support table 61 or inside the processing chamber 60, so that the semiconductor structure 20 can be fully infiltrated, and the cleaning effect of the semiconductor structure 20 can be further improved. In some embodiments, the second temperature ranges from 1°C to 10°C. In one example, the second temperature is 1°C, 3°C, 5°C, 8°C or 10°C. The solidification saturation point of the first fluid is -70°C, but the auxiliary gas will cause loss due to heat conduction during the transmission process. Therefore, in one example, the third temperature is -80°C to -180°C, such as -80°C, -90°C, -100°C, -110°C, -130°C, -150°C or -180°C, so as to ensure that the auxiliary gas can reduce the temperature of the first fluid 31 to its solidification saturation point.

[0090] When the immersion time of the semiconductor structure 20 in the first fluid 31 in the saturated state (i.e., the duration of the pre-cooling step) reaches a preset time (e.g., 1 min to 20 min), the first fluid 31 is stopped from being introduced into the second pipe 78, but the auxiliary gas at the third temperature is still continuously introduced into the processing chamber 60 through the third pipe 71. At the same time, the cooling gas is transmitted to the fourth pipe 73 connected to the processing chamber 60 through the condenser 72 to reduce the temperature of the processing chamber 60 to the first temperature. In the process of reducing the temperature of the processing chamber 60, the rotation speed of the support table 61 can be adjusted in real time according to the temperature in the processing chamber 60. For example, when the temperature of the first fluid 31 is higher than the threshold temperature, the rotation speed of the support table 61 is maintained at 50 rpm; when the temperature of the first fluid 31 is lower than or equal to the threshold temperature, the rotation speed of the support table 61 is maintained at 5 rpm, and the second rotation speed is lower than the first rotation speed; when the temperature of the first fluid 31 drops to the first temperature, the support table 61 stops rotating to further improve the cleaning effect of the semiconductor structure.

[0091] After the first fluid is frozen, the condenser 72 is closed, and the auxiliary gas is stopped from being transmitted to the processing chamber 60, and the second fluid having a fourth temperature higher than the first temperature is transmitted to the processing chamber 60 through the second transmission structure. In one example, when the first fluid 31 and the second fluid are both heavy water, the second transmission structure may also include a second pipe 78, that is, the second transmission structure shares the second pipe 78 with the first transmission structure, and at this time, the second pipe 78 is also connected to a second storage source for storing the second fluid at the fourth temperature. In another example, when the composition of the first fluid 31 is different from that of the second fluid, the second fluid is transmitted to the processing chamber 60 through a fifth pipe different from the second pipe 78. When the composition of the first fluid 31 is different from that of the second fluid, the first fluid may be heavy water, and the second fluid may be water (H2O) or other liquids that will not damage the semiconductor structure 20. Through the heat exchange between the second fluid at the fourth temperature and the first fluid 31 at the first temperature, the first fluid 31 can begin to melt, that is, the first fluid 31 at least partially begins to change from a solid state to a liquid state. As the support platform 61 rotates, the particles 21 are separated from the semiconductor structure 20 by the centrifugal force, the drag force of the second fluid, and the drag force of the first fluid, thereby achieving removal of the particles 21 .

[0092] Afterwards, a drying agent, such as isopropyl alcohol (IPA), can be transferred to the processing chamber 60 through the sixth pipe 79 connected to the first pipe 77, and the support table 61 is driven to rotate at a high speed to remove the first fluid 31 and the second fluid remaining on the semiconductor structure 20. The remaining first fluid 31 and the second fluid are discharged from the processing chamber 60 through the drain cup 74 and the second drain pipe in sequence.

[0093] In one example, the cleaning device for semiconductor structure further includes an exhaust pipe 81 in communication with the processing chamber 60, and a vacuum pump 82 installed in the exhaust pipe 81, so as to exhaust the exhaust gas in the processing chamber 60 through the vacuum pump 82 and the exhaust pipe 81, and adjust the gas pressure in the processing chamber 60. The cleaning device for semiconductor structure further includes a seventh pipeline 80, which is used to transmit a purge gas, etc., into the processing chamber 60 to exhaust the exhaust gas and / or air in the processing chamber 60.

[0094] The semiconductor structure cleaning method and cleaning device provided in some embodiments of this specific implementation manner, by reducing the temperature of the first fluid infiltrating the semiconductor structure to a first temperature, and limiting the first temperature to be lower than or equal to the solidification point of the first fluid, so that the first fluid changes from a liquid state to a solid state, and then when the first fluid is changed from a solid state to a liquid state, on the one hand, the adhesion between the particles to be removed and the semiconductor structure is reduced by the first fluid forming a hydrophobic layer on the surface of the semiconductor structure, so as to facilitate the removal of the particles; on the other hand, the particles are wrapped by the first fluid, and the volume expansion force generated when the first fluid solidifies is used to separate the particles, so that after the first fluid changes from a solid state to a liquid state, the particles can be removed by the flow of the first fluid. The semiconductor structure cleaning method provided in some embodiments of this specific implementation manner reduces damage to the semiconductor structure, improves the efficiency of particle removal, and improves the effect of particle removal.

[0095] The above is only a preferred embodiment of the present disclosure. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present disclosure. These improvements and modifications should also be regarded as within the scope of protection of the present disclosure.

Claims

1. A method for cleaning a semiconductor structure, characterized in that: The steps include: Providing a semiconductor structure, the surface of which has particles to be removed; Perform at least one of the following cycle steps, wherein the cycle steps include: Immersing the semiconductor structure in a first fluid to form a hydrophobic layer on the surface of the semiconductor structure; Lowering the temperature of the first fluid to a first temperature, the first temperature being lower than or equal to a freezing point of the first fluid; The temperature of the first fluid covering the semiconductor structure is increased to remove the particles through the flow of the first fluid.

2. The semiconductor structure cleaning method according to claim 1, characterized in that: The first fluid is heavy water.

3. The semiconductor structure cleaning method according to claim 1, characterized in that: Before immersing the semiconductor structure into the first fluid, the following steps are also included: The semiconductor structure is cleaned using a chemical cleaning agent.

4. The method for cleaning a semiconductor structure according to claim 3, characterized in that: The chemical cleaning agent is a mixed solution of heavy water and hydrofluoric acid, and the volume ratio of hydrofluoric acid to heavy water in the chemical cleaning agent is (1:30) to (1:300).

5. The semiconductor structure cleaning method according to claim 1, characterized in that: The specific steps of immersing the semiconductor structure into the first fluid include: The semiconductor structure is immersed in a first fluid for a preset time, wherein the preset time is 1 min to 20 min, and the first fluid at least soaks the particles.

6. The method for cleaning a semiconductor structure according to claim 1, wherein: The specific steps of immersing the semiconductor structure into the first fluid include: placing the semiconductor structure on a support table in a processing chamber; The first fluid at a second temperature is continuously delivered to the semiconductor structure, and an auxiliary gas at a third temperature is delivered to the processing chamber, wherein the second temperature is higher than a freezing point of the first fluid, and the third temperature is lower than a freezing point of the first fluid.

7. The method for cleaning a semiconductor structure according to claim 6, characterized in that: The second temperature ranges from 1°C to 10°C.

8. The method for cleaning a semiconductor structure according to claim 6, wherein: The auxiliary gas is nitrogen or an inert gas, and the third temperature is lower than -70°C.

9. The method for cleaning a semiconductor structure according to claim 6, wherein: The specific steps of reducing the temperature of the first fluid to a first temperature include: The first fluid is stopped from being transmitted to the semiconductor structure, and the auxiliary gas at the third temperature is continuously transmitted to the processing chamber, so that the temperature of the first fluid remaining on the surface of the semiconductor structure is reduced to the first temperature.

10. The method for cleaning a semiconductor structure according to claim 9, characterized in that: The specific step of lowering the temperature of the first fluid to the first temperature also includes: The support table is rotated, and the rotation speed of the support table is controlled to decrease as the temperature of the first fluid decreases.

11. The method for cleaning a semiconductor structure according to claim 6, wherein: The specific steps of increasing the temperature of the first fluid covering the semiconductor structure to remove the particles through the flow of the first fluid include: A second fluid at a fourth temperature is transmitted to the semiconductor structure, and the support table is controlled to rotate, wherein the fourth temperature is higher than a freezing point of the first fluid.

12. The method for cleaning a semiconductor structure according to claim 11, characterized in that: The second fluid is heavy water.

13. The method for cleaning a semiconductor structure according to claim 1, wherein: The cycle step is executed 1 to 10 times.

14. The method for cleaning a semiconductor structure according to claim 1, wherein: After performing the cycle step at least once, the method further comprises the following steps: The semiconductor structure is dried.

15. A cleaning device for a semiconductor structure, characterized in that: A method for cleaning a semiconductor structure according to any one of claims 1 to 14, comprising: a processing chamber for accommodating a semiconductor structure to be cleaned, wherein particles to be removed are attached to a surface of the semiconductor structure; a first transfer structure, used to transfer a first fluid to the processing chamber, wherein the first fluid is used to form a hydrophobic layer on the surface of the semiconductor structure; a condenser, configured to reduce the temperature of the processing chamber so that the temperature of the first fluid in the processing chamber drops to a first temperature, wherein the first temperature is lower than or equal to a freezing point of the first fluid; The second transfer structure is used to transfer a second fluid at a fourth temperature to the processing chamber, and to increase the temperature of the first fluid covering the semiconductor structure through the second fluid to remove the particles through the flow of the first fluid, wherein the fourth temperature is higher than the freezing point of the first fluid.

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