Wafer cleaning process

Abstract

The present application relates to wafer cleaning technical field, disclose a kind of wafer cleaning process, it includes first cleaning, second cleaning, third cleaning and drying treatment, process applicability is strong, can improve the surface cleanliness of wafer, reduce wafer texturing after adverse ratio and promote battery photoelectric conversion efficiency;At the same time, the present application verifies more suitable for cleaning wafer cleaning liquid ratio mode, cleaning liquid cost is reasonable, and cleaning capacity is higher.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer cleaning, in particular to a wafer cleaning process. BACKGROUND

[0002] Gallium arsenide is an important semiconductor material, and gallium arsenide can be made into a semi-insulating high-resistance material with a resistivity of more than 3 orders of magnitude higher than silicon and germanium, which is used to make integrated circuit substrates and infrared detectors, etc. Gallium arsenide is widely used in microwave devices, high-speed digital circuits, mobile phones, satellite communications, microwave point-to-point links and radar systems. Due to the high surface activity of gallium arsenide, the particles generated in the cutting process of gallium arsenide wafers are easily attached to the surface of the gallium arsenide wafers, and the surface of the gallium arsenide wafers needs to be cleaned during the manufacturing process. SUMMARY

[0003] The purpose of the present application is to provide a wafer cleaning process, which effectively improves the surface cleanliness of the wafer, reduces the wafer defect rate, and has high cleaning capacity.

[0004] In order to achieve the above purpose, the present application provides a wafer cleaning process, which comprises:

[0005] using a first cleaning liquid to clean the wafer for the first time, wherein the first cleaning liquid is a mixed solution of isopropyl alcohol and alcohol;

[0006] using a second cleaning liquid to clean the wafer for the second time, wherein the second cleaning liquid is a mixed solution of ammonium hydroxide, hydrogen peroxide and water;

[0007] using a third cleaning liquid to clean the wafer for the third time, wherein the third cleaning liquid is a mixed solution of hydrochloric acid, hydrogen peroxide and water;

[0008] the wafer is subjected to a drying treatment.

[0009] Preferably, between the first cleaning and the second cleaning, the wafer needs to be cleaned with pure water for the first time;

[0010] between the second cleaning and the third cleaning, the wafer needs to be cleaned with pure water for the second time;

[0011] after the third cleaning, the wafer needs to be cleaned with pure water for the third time.

[0012] Preferably, after the third cleaning with pure water, the wafer needs to be operated as follows:

[0013] cleaning the wafer with alcohol;

[0014] cleaning the wafer with isopropyl alcohol.

[0015] Preferably, the first cleaning solution is a mixed solution with a volume ratio of isopropyl alcohol: alcohol = 1:1, wherein the concentration of the isopropyl alcohol is greater than or equal to 99%, and the concentration of the alcohol is greater than or equal to 99%.

[0016] Preferably, the second cleaning solution is a mixed solution with a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1: (3-4): (7-9), wherein the concentration of the ammonium hydroxide is 28%-30%, and the concentration of the hydrogen peroxide is 30%-32%.

[0017] Preferably, the third cleaning solution is a mixed solution with a volume ratio of hydrochloric acid: hydrogen peroxide: water = 5: (2-3): (18-22), wherein the concentration of the hydrochloric acid is 36%-38%, and the concentration of the hydrogen peroxide is 30%-32%.

[0018] Preferably, the cleaning time of the first cleaning, the second cleaning, and the third cleaning is 15-60s.

[0019] Preferably, during the first cleaning, the second cleaning, the third cleaning, the first pure water cleaning, the second pure water cleaning, and the third pure water cleaning, the wafer is in a rotating state, and the rotating speed is 20-30r / min.

[0020] Preferably, the drying treatment comprises:

[0021] rotating the wafer and blowing dry the wafer with nitrogen.

[0022] Preferably, during the drying treatment, the temperature of the nitrogen is 28-35℃, the drying time is 270-320s, the wafer is in a rotating state, and the rotating speed is 150-200r / min.

[0023] The wafer cleaning process provided by the present application has the beneficial effects compared with the prior art in that:

[0024] The wafer cleaning process provided by the present application comprises first cleaning, second cleaning, third cleaning, and drying treatment, has strong process applicability, can improve the surface cleanliness of the wafer, reduce the poor ratio of the wafer after texturing, and improve the battery photoelectric conversion efficiency; at the same time, the present application verifies a more suitable cleaning solution ratio for cleaning the wafer, the cleaning solution cost is reasonable, and the cleaning productivity is high. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A wafer cleaning process flowchart provided by an embodiment of the present application is provided;

[0026] Figure 2 A schematic diagram of the overall structure of a cleaning table provided by an embodiment of the present application is provided;

[0027] Figure 3 Structure diagram of the carding mechanism provided by the embodiment of the present application;

[0028] Figure 4 Structure diagram of the cleaning tank provided by the embodiment of the present application;

[0029] Figure 5 Structure diagram of the fixing member and the carding mechanism provided by the embodiment of the present application;

[0030] Figure 6 Structure diagram of the fixing member provided by the embodiment of the present application.

[0031] In the figure: 100, cleaning table; 200, wafer fixing device;

[0032] 1, carding mechanism; 11, first panel; 12, second panel; 13, first connecting member; 14, second connecting member; 15, plug-in slot; 16, first through hole; 17, second through hole;

[0033] 2, cleaning tank; 21, outer cylinder; 22, inner cylinder; 23, cleaning cavity; 24, first water pipe; 25, first water pump; 26, filtering area; 27, second water pipe; 28, second water pump;

[0034] 3, drying tank; 31, drying cavity; 32, cover plate;

[0035] 4, connecting assembly; 41, connecting rod; 42, mounting panel; 43, fixing member;

[0036] 5, cabinet body; 6, ventilation opening; 7, ventilation duct; 8, display device; 9, partition plate. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments of the present application.

[0038] It should be understood that, in the description of the present application, the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. That is, the features with "first", "second" can explicitly or implicitly include one or more features. In addition, unless otherwise specified, the meaning of "multiple" is two or more.

[0039] It should be noted that, in the description of the present application, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] As shown in Figure 1 The wafer cleaning process provided by the present application includes first cleaning, second cleaning, third cleaning and drying treatment, and has strong process applicability, can improve the surface cleanliness of the wafer, reduce the wafer bad rate after texturing and improve the battery photoelectric conversion efficiency; at the same time, the present application verifies a more suitable cleaning liquid ratio for cleaning the wafer, and the cleaning liquid cost is reasonable, and the cleaning capacity is high.

[0041] S100, first cleaning of the wafer using a first cleaning liquid, wherein the first cleaning liquid is a mixed solution of isopropyl alcohol and alcohol;

[0042] S200, second cleaning of the wafer using a second cleaning liquid, wherein the second cleaning liquid is a mixed solution of ammonium hydroxide, hydrogen peroxide and water;

[0043] S300, third cleaning of the wafer using a third cleaning liquid, wherein the third cleaning liquid is a mixed solution of hydrochloric acid, hydrogen peroxide and water;

[0044] S400, drying treatment of the wafer.

[0045] The wafer cleaning process provided by the present application includes first cleaning, second cleaning, third cleaning and drying treatment, and has strong process applicability, can improve the surface cleanliness of the wafer, reduce the wafer bad rate after texturing and improve the battery photoelectric conversion efficiency; at the same time, the present application verifies a more suitable cleaning liquid ratio for cleaning the wafer, and the cleaning liquid cost is reasonable, and the cleaning capacity is high.

[0046] Specifically, the above cleaning process is performed on the wafer using the cleaning platform 100, which comprises a plurality of cleaning tanks 2, drying tanks 3, a transfer device, wafer fixing devices 200 capable of fixing a plurality of wafers, and a controller. The wafer fixing devices 200 are transferred to the cleaning tanks 2 and drying tanks 3 by the transfer device to quickly complete the cleaning and drying of the plurality of wafers, effectively improving the wafer processing efficiency and achieving a streamlined operation.

[0047] As shown in Figure 3 The wafer fixing device 200 comprises a cassette box and a cassette mechanism 1. The cassette box is provided with an accommodation space for accommodating wafers. A plurality of wafers can be stored in the accommodation space and uniformly clamped in the clamping grooves, so that the adjacent wafers have gaps and are not adsorbed and adhered together, and are reasonably placed. The cassette mechanism 1 is provided with a plurality of insertion grooves 15 around the axis thereof for inserting the cassette box. Thus, the cassette box with the wafers inserted is inserted into the insertion groove 15, and the plurality of cassette boxes are combined together by the cassette mechanism 1. The combination of the cassette box and the cassette mechanism 1 realizes the batch fixing and insertion of the wafers, so that the wafers can be processed in batches, the processing efficiency is doubled, and the processing work of the batch wafers is very suitable.

[0048] In the embodiment, the cassette box comprises two oppositely arranged cassette plates with a gap therebetween. The two ends of the cassette plates are respectively provided with baffle plates connected between the two cassette plates. Thus, the two cassette plates and the two baffle plates together enclose an accommodation space for accommodating wafers. The inner side of the cassette plate is provided with a plurality of clamping grooves for inserting wafers. The plurality of clamping grooves are uniformly and spaced apart along the length direction of the cassette plate. Preferably, the number of clamping grooves is 10-30. The two cassette plates and the two baffle plates together enclose a rectangular cuboid frame-shaped accommodation space. A plurality of wafers are stored in the accommodation space and uniformly clamped in the clamping grooves, so that the adjacent wafers have gaps and are not adsorbed and adhered together, and are reasonably placed. Preferably, the clamping grooves are through grooves penetrating through the two sides of the cassette plate. Thus, when the wafers are cleaned, the cleaning liquid can fully contact the wafers through the through grooves. The cassette mechanism 1 is a hollow cylindrical frame. The cassette mechanism 1 is provided with a plurality of insertion grooves 15 around the axis thereof for inserting the cassette box. Preferably, the insertion grooves 15 extend along the length direction of the cassette mechanism 1. The cross-sectional shape of the insertion grooves 15 corresponds to the cross-sectional shape of the cassette box. Further, the length of the insertion grooves 15 is consistent with the length of the cassette box.

[0049] As shown in Figure 3As shown, the cassette mechanism 1 comprises a first panel 11, a second panel 12, a first connecting piece 13 and a second connecting piece 14 connected between the first panel 11 and the second panel 12, the first connecting piece 13 is arranged on the central axis of the cassette mechanism 1, and a plurality of second connecting pieces 14 are arranged at the edge of the cassette mechanism 1, and the first connecting piece 13 and the second connecting piece 14 jointly form a plug-in slot 15; at the same time, a plurality of first through holes 16 are formed on the first panel 11 around the axis thereof, the cross-sectional shape of each first through hole 16 corresponds to the cross-sectional shape of the cassette box, and the cassette box can be inserted into the plug-in slot 15 formed by the first connecting piece 13 and the second connecting piece 14 at the first through hole 16. Figure 4 As shown, the first panel 11, the second panel 12, the first connecting piece 13 and the second connecting piece 14 jointly form a hollow cylindrical frame, and the first panel 11 and the second panel 12 have the same structure, four first through holes 16 are arranged on the first panel 11 around the central axis thereof, and four second through holes 17 are arranged on the second panel 12 around the central axis thereof, in actual plug-in, one end of the cassette box is inserted into the plug-in slot 15 at the first through hole 16, and the other end of the cassette box reaches the second through hole 17, the cross-sectional shape of the first through hole 16 is the same as that of the second through hole 17, and the cross-sectional shape of the first through hole 16 and the second through hole 17 is the same as that of the cassette box, so that the two ends of the cassette box are respectively embedded in the first through hole 16 and the second through hole 17, and the middle part of the cassette box is arranged in the plug-in slot 15, and the first connecting piece 13 and the second connecting piece 14 jointly wrap the cassette box, thereby realizing the plug-in combination of the cassette mechanism 1 and the cassette box.

[0050] Four cassette boxes can be plugged into the cassette mechanism 1 at the same time, since the cassette mechanism 1 is a hollow cylindrical frame, the cleaning liquid can enter the plug-in slot 15 and fully contact the wafers in the cassette box, the wafer fixing device 200 provided in the embodiment has simple and reasonable structure, can batch insert and place wafers, and does not hinder the free contact between the cleaning liquid and the wafers, the wafer fixing device 200 provided in the embodiment can be used for batch processing of wafers, and has high practicability.

[0051] As shown in the figure, Figure 2 The cleaning table 100 provided in the embodiment further comprises a cabinet 5, the inside of the cabinet 5 is provided with a cavity, the drying groove 3 and the cleaning groove 2 are horizontally arranged in the cavity, and the wafer can be processed in a water flow manner. Preferably, a partition plate 9 is arranged between the drying groove 3 and the cleaning groove 2, so as to prevent the cleaning liquid in the cleaning groove 2 from affecting each other.

[0052] The cleaning tank 2 is divided into a first cleaning tank 2a, a second cleaning tank 2b, a third cleaning tank 2c, a fourth cleaning tank 2d, a fifth cleaning tank 2e, a sixth cleaning tank 2f and a seventh cleaning tank 2g. The shape of the cleaning tank 2 and the drying tank 3 is not limited, and in some embodiments, the shape can be a cuboid, a cylinder or a quadrangular frustum.

[0053] As shown in Figure 4 The cleaning tank 2 includes an outer cylinder 21 and an inner cylinder 22 sleeved inside the outer cylinder 21. The inner cylinder 22 has a cleaning cavity 23 with an open top. A water outlet is arranged on the bottom plate or the side plate of the inner cylinder 22. A filter area 26 is arranged in the outer cylinder 21. The cleaning liquid flowing out of the water outlet is sucked back into the inner cylinder 22 by a pump body after passing through the filter area 26, thereby forming a circulating water path.

[0054] Specifically, the outer cylinder 21 has a containing cavity with an open top. The inner cylinder 22 is arranged in the containing cavity. The upper edge of the inner cylinder 22 is suspended on the top of the side wall of the outer cylinder 21, and / or a support is arranged on the bottom plate of the outer cylinder 21 to support the inner cylinder 22, thereby achieving stable sleeving of the inner cylinder 22 in the outer cylinder 21. A water outlet is arranged on the bottom plate or the side plate of the inner cylinder 22. A first water pipe 24 is arranged at the water outlet. The water inlet of the first water pipe 24 is arranged at the lower end of the inner cylinder 22. A first water pump 25 is arranged on the first water pipe 24. The cleaning liquid in the inner cylinder 22 is pumped to the outer cylinder 21 by the first water pump 25. Meanwhile, a filter area 26 is arranged in the outer cylinder 21. The filter area 26 is provided with a chemical filter element. The chemical filter element can filter and purify the cleaning liquid. A second water pipe 27 is connected to the water outlet of the filter area 26 and the inner cylinder 22. A second water pump 28 is arranged on the second water pipe 27. The cleaning liquid filtered and purified by the filter area 26 is pumped back to the inner cylinder 22 by the second water pump 28. The first water pump 25 and the second water pump 28 are electrically connected to a controller. In this way, a circulating water path is formed. On one hand, the cleaning liquid in the inner cylinder 22 is subjected to circulating filtration treatment. On the other hand, the flowability of the cleaning liquid in the inner cylinder 22 is improved, and the contact with the wafer is strengthened.

[0055] As shown in Figure 2As shown, the drying tank 3 has a top-open drying cavity 31, and a drying device for drying the wafer is arranged in the drying tank 3, wherein the drying device comprises a gas conveying pipe provided with an air inlet and an air outlet, the air inlet is connected to an external air source, the air outlet is communicated with the drying cavity 31, and an air inlet valve is arranged on the air inlet pipe and electrically connected to the controller, so that the external air source is introduced into the drying cavity 31 to blow and dry the wafer. In order to enhance the drying effect, preferably, the opening end of the drying tank 3 is movably provided with a cover plate 32, the cover plate 32 covers the top of the drying tank 3, so that the drying cavity 31 is relatively closed and the external air source is not easy to flow out. At the same time, the cover plate 32 is provided with a through hole communicated with the drying cavity 31, and the wafer fixing device 200 can enter and exit the drying cavity 31 from the through hole. Preferably, at least one air vent 6 communicated with the cavity is arranged on the cabinet 5, and part of the air vents 6 is provided with an air duct 7 to discharge the drying gas leaked from the drying cavity 31.

[0056] Due to the multiple wafer processing steps, the wafer needs to be transported multiple times in different cleaning tanks 2 and drying tanks 3 to sequentially perform the related processing steps. Based on this, the cleaning table 100 provided by the embodiment further comprises a transfer device for transferring the wafer to the cleaning tank 2 and the drying tank 3 to quickly complete the cleaning and drying treatment of the wafer in different cleaning tanks 2 and drying tanks 3.

[0057] Preferably, the transfer device comprises a horizontal transfer device and a vertical transfer device, the horizontal transfer device is arranged above the cleaning tank 2 and the drying tank 3 in a horizontal direction, and a first driving member is used to drive the horizontal movement of the horizontal transfer device, and the movement track of the horizontal transfer device covers the drying tank 3 and all the cleaning tanks 2; the vertical transfer device is arranged above the cleaning tank 2 in a vertical direction, the upper end of the vertical transfer device is connected to the horizontal transfer device, the lower end of the vertical transfer device is connected to the wafer fixing device 200, and a second driving member is used to drive the vertical transfer device to move up and down; the first driving member and the second driving member are electrically connected to the controller. It can be understood that the controller controls the horizontal movement and the vertical movement of the horizontal transfer device and the vertical transfer device, so that the wafer fixing device 200 inserted with the wafer can be quickly transferred to the cleaning tank 2 and the drying tank 3, and the mechanical operation can effectively improve the wafer processing efficiency.

[0058] Preferably, the horizontal transfer device comprises a plurality of horizontal and vertical staggered guide rails, at least one sliding block is movably arranged on the guide rails, at least one vertical transfer device is connected to each sliding block, and the sliding block is electrically connected to the first driving member; the vertical transfer device comprises a telescopic rod, the upper end of the telescopic rod is connected to the sliding block, and the lower end of the telescopic rod is connected to the wafer fixing device 200. In actual installation, the plurality of horizontal and vertical staggered guide rails are installed on the inner side of the top plate of the cabinet 5, and the drying tank 3 and the cleaning tank 2 are horizontally arranged on the upper surface of the bottom plate of the cabinet 5.

[0059] Preferably, in some preferred embodiments, the wafer fixing device 200 is connected to the transfer device through a connecting assembly 4, as shown in Figure 5 、 6 The connecting assembly 4 comprises a connecting rod 41, a mounting panel 42 and a fixing member 43 for fixing the wafer fixing device 200, which are connected in sequence from top to bottom, the upper end of the connecting rod 41 is rotationally connected with the lower end of the telescopic rod, and the lower end of the connecting rod 41 is fixedly connected with the mounting panel 42, wherein the lower surface of the mounting panel 42 is connected with the fixing member 43, and in this embodiment, the fixing member 43 is a plurality of hooks, which are matched to hook the wafer fixing device 200, that is, the wafer fixing device 200 is rotationally connected with the telescopic rod through the connecting assembly 4. It can be understood that when the telescopic rod is extended downward into the cleaning cavity 23 or the drying cavity 31, the connecting rod 41 rotates relative to the telescopic rod, thereby driving the wafer fixing device 200 with the wafer inserted therein to rotate, and in the process of rotation, the wafer can agitate the cleaning liquid, thereby enhancing the contact between the wafer and the cleaning liquid, and reducing the cleaning dead angle.

[0060] Preferably, in some preferred embodiments, the cabinet 5 is provided with a display device 8, which is electrically connected with the controller, and further, the display device 8 is a touch display device 8, and the operator can control the wafer processing device 100 by touching the display device 8.

[0061] Meanwhile, the first cleaning tank 2a is filled with the first cleaning liquid, the second cleaning tank 2b is filled with pure water, the third cleaning tank 2c is filled with the second cleaning liquid, the fourth cleaning tank 2d is filled with the third cleaning liquid, the fifth cleaning tank 2e is filled with pure water, the sixth cleaning tank 2f is filled with alcohol, and the seventh cleaning tank 2g is filled with isopropyl alcohol.

[0062] Based on the above structure, first, a plurality of wafer to be cleaned is inserted into the plug box, and then the plug box with the wafer inserted is inserted into the plug mechanism 1; then, the hook is hooked with the wafer fixing device 200 with the wafer, that is, the wafer fixing device 200 is rotationally connected with the telescopic rod through the connecting assembly 4, thereby completing the wafer fixing work before cleaning.

[0063] Then, the first cleaning is performed. The first driving member drives the sliding block to move horizontally, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the first cleaning tank 2a. Then, the second driving member drives the telescopic rod to extend downward into the first cleaning tank 2a, so that the wafer fixing device 200 in which the wafer is inserted is extended into the first cleaning tank 2a, and the wafer is immersed in the first cleaning liquid. At the same time, the connecting rod 41 rotates relative to the telescopic rod, thereby driving the wafer fixing device 200 in which the wafer is inserted to rotate. In this embodiment, the first cleaning liquid is a mixed solution with a volume ratio of isopropyl alcohol: alcohol = 1:1, wherein the concentration of the isopropyl alcohol is greater than or equal to 99%, and the concentration of the alcohol is greater than or equal to 99%. The wafer is cleaned in the first cleaning liquid for 40 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute. It should be noted that the first cleaning liquid is a mixed solution composed of isopropyl alcohol and alcohol. The isopropyl alcohol can remove the organic matter on the surface of the wafer, but the isopropyl alcohol has weak hydrophilicity and the alcohol has strong hydrophilicity. Therefore, the mixed solution of isopropyl alcohol and alcohol is used to increase the hydrophilicity of the first cleaning liquid and better remove the organic matter on the surface of the wafer.

[0064] After the first cleaning is completed, the wafer needs to be cleaned with pure water for the first time to remove the residual first cleaning liquid on the surface of the wafer, so as to avoid the first cleaning liquid mixed in the second cleaning liquid and affect the effect of the second cleaning. Specifically, after the wafer is cleaned in the first cleaning liquid for 40 seconds, the connecting rod 41 stops rotating, the second driving member drives the telescopic rod to retract upward, the first driving member drives the sliding block to slide above the second cleaning tank 2b, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the second cleaning tank 2b. Then, the second driving member drives the telescopic rod to extend downward into the second cleaning tank 2b, so that the wafer fixing device 200 in which the wafer is inserted is extended into the second cleaning tank 2b, and the wafer is immersed in the pure water. In the first pure water cleaning process, the wafer is cleaned for 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute.

[0065] After the first pure water cleaning is completed, the wafer is further cleaned for the second time, the connecting rod 41 stops rotating, the second driving member drives the telescopic rod to retract upward, the first driving member drives the sliding block to slide above the third cleaning tank 2c again, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the third cleaning tank 2c, then the second driving member drives the telescopic rod to be able to extend downward into the third cleaning tank 2c, so as to drive the wafer fixing device 200 in which the wafer is inserted to extend into the third cleaning tank 2c, so that the wafer is immersed in the second cleaning liquid; the second cleaning liquid is a mixed solution with a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1: (3-4): (7-9), optionally, a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:3:7, a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:3:8, a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:4:7 or a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:3:8; in this embodiment, the second cleaning liquid is a mixed solution with a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:3:7, the concentration of ammonium hydroxide is 28%-30%, the concentration of hydrogen peroxide is 30%-32%, the cleaning time of the wafer in the second cleaning liquid is 20 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute. It should be noted that the second cleaning liquid is a weak acid and weak base mixed solution composed of ammonium hydroxide, hydrogen peroxide and water, ammonium hydroxide can remove small particles on the surface of the wafer, and hydrogen peroxide increases the thickness of the oxidation layer to protect the surface structure of the wafer.

[0066] Similarly, after the second cleaning is completed, the wafer needs to be cleaned for the second time with pure water to remove the residual second cleaning liquid on the surface of the wafer, so as to avoid the mixing of the second cleaning liquid in the third cleaning liquid and affect the effect of the third cleaning. Specifically, after the wafer is cleaned in the second cleaning liquid for 20 seconds, the connecting rod 41 stops rotating, the second driving member drives the telescopic rod to retract upward, the first driving member drives the sliding block to slide above the second cleaning tank 2b again, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the second cleaning tank 2b, then the second driving member drives the telescopic rod to be able to extend downward into the second cleaning tank 2b, so as to drive the wafer fixing device 200 in which the wafer is inserted to extend into the second cleaning tank 2b, so that the wafer is immersed in pure water; during the second pure water cleaning process, the cleaning time of the wafer is 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute.

[0067] After the second pure water cleaning is completed, the wafer is further cleaned for the third time, the connecting rod 41 stops rotating, the second driving member drives the telescopic rod to retract upward, the first driving member drives the sliding block to slide above the fourth cleaning tank 2d again, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the fourth cleaning tank 2d, then the second driving member drives the telescopic rod to be able to extend downward into the fourth cleaning tank 2d, so as to drive the wafer fixing device 200 in which the wafer is inserted to extend into the fourth cleaning tank 2d, so that the wafer is immersed in the third cleaning liquid; the third cleaning liquid is a mixed solution with a volume ratio of hydrochloric acid: hydrogen peroxide: water = 5: (2-3): (18-22), optionally, the volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:2:18, the volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:3:20, the volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:2:20 or the volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:2:22, in this embodiment, the third cleaning liquid is a mixed solution with a volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:2:20, the concentration of the hydrochloric acid is 36%-38%, and the concentration of the hydrogen peroxide is 30%-32%. The cleaning time of the wafer in the third cleaning liquid is 15 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute. It should be noted that the hydrochloric acid is a strong acid, which can further remove small particles remaining on the surface of the wafer, and the hydrogen peroxide can form an oxide film on the surface of the wafer to protect the surface structure of the wafer and prevent the wafer from being eroded by the hydrochloric acid.

[0068] Similarly, after the third cleaning is completed, the wafer needs to be cleaned for the third time with pure water to remove the third cleaning liquid remaining on the surface of the wafer, so as to avoid the third cleaning liquid from being mixed in the subsequent processing liquid and affecting the effect of the subsequent processing. Specifically, after the wafer is cleaned in the third cleaning liquid for 15 seconds, the connecting rod 41 stops rotating, the second driving member drives the telescopic rod to retract upward, and the first driving member drives the sliding block to slide above the fifth cleaning tank 2e again, so that the longitudinal projection of the sliding block falls into the longitudinal projection of the fifth cleaning tank 2e, then the second driving member drives the telescopic rod to be able to extend downward into the fifth cleaning tank 2e, so as to drive the wafer fixing device 200 in which the wafer is inserted to extend into the fifth cleaning tank 2e, so that the wafer is immersed in pure water; during the third pure water cleaning, the cleaning time of the wafer is 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute.

[0069] After the third pure water cleaning is completed, the wafer also needs to be operated as follows:

[0070] First, the wafer is cleaned with alcohol, and then cleaned again with isopropyl alcohol. It should be noted that the purpose of cleaning the wafer with alcohol and isopropyl alcohol is mainly to dilute the water on the surface of the wafer and reduce the water remaining on the surface of the wafer, thereby greatly reducing the probability of white spots. In this embodiment, the sixth cleaning tank 2f is filled with alcohol, and the seventh cleaning tank 2g is filled with isopropyl alcohol. The wafer fixing device 200 with the wafer inserted is sent into the sixth cleaning tank 2f and the seventh cleaning tank 2g in turn by the transfer device. In the sixth cleaning tank 2f, the wafer cleaning time is 30 seconds, and the wafer is in a rotating state with a rotation rate of 30 revolutions per minute. In the seventh cleaning tank 2g, the wafer cleaning time is 60 seconds, and the wafer is in a rotating state with a rotation rate of 30 revolutions per minute.

[0071] It should be noted that when the wafer fixing device 200 with the wafer inserted is inserted into the cleaning tank 2 for cleaning operation, the controller simultaneously starts the first water pump 25 and the second water pump 28 in the corresponding cleaning tank 2. On the one hand, the cleaning liquid in the inner cylinder 22 is circulated and filtered; on the other hand, the flowability of the cleaning liquid in the inner cylinder 22 is improved to strengthen the contact with the wafer, thereby enhancing the cleaning effect of the wafer.

[0072] The above completes the cleaning of the wafer.

[0073] Next, the wafer is dried. The first driving member drives the sliding block to slide above the drying tank 3 again, so that the longitudinal projection of the sliding block falls within the longitudinal projection of the drying tank 3. Then, the second driving member drives the telescopic rod to extend downward from the through hole into the drying tank 3, thereby driving the wafer fixing device 200 with the wafer inserted to extend into the drying tank 3. At this time, the controller controls the inlet valve to open, and hot nitrogen gas is introduced into the drying cavity 31 to blow and dry the wafer. In this embodiment, the drying tank 3 has a drying cavity 31 that can be heated, and the temperature of the drying cavity 31 is controlled at 28-35°. In the drying tank 3, the drying time of the wafer is 300 seconds, and the wafer is in a rotating state with a rotation rate of 180 revolutions per minute. Compared with the spin-drying method, the spin-drying method is easy to leave water vapor on the surface of the wafer, while the nitrogen drying provided by the present embodiment will not leave any residue, and the probability of white spots will be greatly reduced.

[0074] Embodiment:

[0075] S1, wafer fixing and installation: insert a plurality of wafers to be cleaned into the plug-in box, and then insert the plug-in box with the wafers into the plug-in mechanism 1. Then, the hook hooks the wafer fixing device 200 with the wafer.

[0076] S2, first cleaning: the wafer is immersed in a first cleaning solution, the first cleaning solution is a mixed solution with a volume ratio of isopropyl alcohol: alcohol = 1:1, the wafer is cleaned in the first cleaning solution for 40 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0077] S3, first pure water cleaning: the wafer is immersed in pure water, the wafer is cleaned for 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0078] S4, second cleaning: the wafer is immersed in a second cleaning solution, the second cleaning solution is a mixed solution with a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1:3:7, the wafer is cleaned in the second cleaning solution for 20 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0079] S5, second pure water cleaning: the wafer is immersed in pure water, the wafer is cleaned for 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0080] S6, third cleaning: the wafer is immersed in a third cleaning solution, the third cleaning solution is a mixed solution with a volume ratio of hydrochloric acid: hydrogen peroxide: water = 5:2:20, the wafer is cleaned in the third cleaning solution for 15 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0081] S7, third pure water cleaning: the wafer is immersed in pure water, the wafer is cleaned for 60 seconds, and the wafer is in a rotating state with a rotating speed of 30 revolutions per minute;

[0082] S8, subsequent processing: the wafer is cleaned with alcohol, and then the wafer is cleaned again with isopropyl alcohol

[0083] S9, drying processing: the wafer is inserted into a drying cavity 31, hot nitrogen gas is introduced into the drying cavity 31, the temperature of the drying cavity 31 is controlled at 28-35°, the drying time of the wafer is 300 seconds, and the wafer is in a rotating state with a rotating speed of 180 revolutions per minute.

[0084] Comparative example:

[0085] S1: the wafer is immersed in sulfuric acid with a concentration of 96% and a temperature of 65°C for 5 seconds;

[0086] S2: the wafer is immersed in sulfuric acid with a concentration of 96% and a temperature of room temperature for 3 seconds;

[0087] S3: the wafer is immersed in a container containing pure water, and the container is kept in a water overflow state, the cleaning time is 45s;

[0088] S4: the wafer is immersed in a first mixed solution composed of ammonium hydroxide: hydrogen peroxide: water = 1:2:3 by volume, the temperature of the first mixed solution is 4°C, the cleaning time is 45 seconds, and the wafer is in a rotating state so that the wafer surface is uniformly subjected to the liquid;

[0089] S5: the wafer is immersed in a container containing pure water, and the container is kept in a water overflow state, the cleaning time is 45 seconds;

[0090] S6: the wafer is immersed in a second mixed solution composed of ammonium hydroxide: hydrogen peroxide = 3:7 by volume, the temperature of the second mixed solution is normal temperature, the cleaning time is 30 seconds, and the wafer is in a rotating state so that the wafer surface is uniformly subjected to the liquid;

[0091] S7: the wafer is immersed in a container containing pure water, and the container is kept in a water overflow state, the cleaning time is 45 seconds;

[0092] S8: the wafer is immersed in a third mixed solution composed of ammonium hydroxide: hydrogen peroxide: water = 3:1:40 by volume, the temperature of the third mixed solution is normal temperature, the cleaning time is 45 seconds, and the wafer is in a rotating state so that the wafer surface is uniformly subjected to the liquid;

[0093] S9: the wafer is immersed in a container containing pure water, and the container is kept in a water overflow state, the cleaning time is 30 seconds;

[0094] S10: the wafer is immersed in hydrogen peroxide, the cleaning time is 45 seconds, and the wafer is in a rotating state so that the wafer surface is uniformly subjected to the liquid;

[0095] S11: the wafer is immersed in a container containing pure water, and the container is kept in a water overflow state, the cleaning time is 45 seconds;

[0096] S12: spin-drying.

[0097] Through experiments, it is found that after the wafer is treated by the cleaning process provided in the embodiment, the particle number measured by Tencor 0.3um is less than 15, the yield is greater than 95%, the white spot ratio is 2 per ten thousand, and the copper content is 0.3; after the wafer is treated by the cleaning process provided in the comparative example, the particle number measured by Tencor 0.3um is less than 150, the yield is 60%, the white spot ratio is 10 per ten thousand, and the copper content is 1.5; compared with the comparative example, the wafer treated by the cleaning process provided in the embodiment has fewer bright spots on the wafer surface, fewer particles, lower white spot ratio, lower copper content, and higher yield.

[0098] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A wafer cleaning process, characterized by, The wafer is cleaned by a cleaning table, the cleaning table comprises: a plurality of cleaning tanks, a drying tank, a drying device, a transfer device, a wafer fixing device, a connecting assembly and a controller, the drying tank has a drying cavity with a top opening, and the drying device for drying the wafer is arranged in the drying tank; the controller is electrically connected with the transfer device, the wafer fixing device is rotatably connected to the transfer device through the connecting assembly, and the transfer device is used to transfer the wafer fixing device fixed with the wafer to the corresponding cleaning tank and drying tank; the wafer fixing device comprises a chucking mechanism and a chucking box for fixing the wafer, and a plurality of insertion grooves for inserting the chucking box are arranged on the chucking mechanism around the axis of the chucking mechanism; The wafer cleaning process comprises the following steps: a plurality of wafers to be cleaned are inserted into the chucking box, then the chucking box inserted with the wafers is inserted into the chucking mechanism, and then the transfer device transfers the wafer fixing device fixed with the wafers to the corresponding cleaning tank; the wafer is immersed in the corresponding cleaning tank filled with a first cleaning liquid, and the wafer is cleaned with the first cleaning liquid for the first time, and the wafer is in a rotating state to remove organic matter on the surface of the wafer, wherein the first cleaning liquid is a mixed solution of isopropyl alcohol and alcohol, the first cleaning liquid is a mixed solution with a volume ratio of isopropyl alcohol to alcohol being 1:1, the concentration of the isopropyl alcohol is greater than or equal to 99%, and the concentration of the alcohol is greater than or equal to 99%; the wafer is immersed in the corresponding cleaning tank filled with a second cleaning liquid, and the wafer is cleaned with the second cleaning liquid for the second time, and the wafer is in a rotating state, wherein the second cleaning liquid is a mixed solution of ammonium hydroxide, hydrogen peroxide and water, and between the first cleaning and the second cleaning, the wafer needs to be cleaned with pure water for the first time, and the wafer is in a rotating state during the first pure water cleaning; the wafer is immersed in the corresponding cleaning tank filled with a third cleaning liquid, and the wafer is cleaned with the third cleaning liquid for the third time, and the wafer is in a rotating state, wherein the third cleaning liquid is a mixed solution of hydrochloric acid, hydrogen peroxide and water, and the third cleaning liquid is a mixed solution with a volume ratio of hydrochloric acid to hydrogen peroxide to water being 5:(2-3):(18-22), the concentration of the hydrochloric acid is 36%-38%, and the concentration of the hydrogen peroxide is 30%-32%; between the second cleaning and the third cleaning, the wafer needs to be cleaned with pure water for the second time, and the wafer is in a rotating state during the second pure water cleaning; after the third cleaning is completed, the wafer needs to be cleaned with pure water for the third time, and the wafer is in a rotating state; after the third pure water cleaning is completed, the wafer is cleaned with alcohol; the wafer is cleaned with isopropyl alcohol; the wafer is dried.

2. The wafer cleaning process of claim 1, wherein: The second cleaning solution is a mixed solution with a volume ratio of ammonium hydroxide: hydrogen peroxide: water = 1: (3-4): (7-9), the concentration of the ammonium hydroxide is 28%-30%, and the concentration of the hydrogen peroxide is 30%-32%.

3. The wafer cleaning process of claim 1, wherein: The cleaning time of the first, second and third cleanings is 15-60 seconds.

4. The wafer cleaning process of claim 1, wherein: The rotation rate of the wafer is 20-30 revolutions per minute during the first, second, third, first pure water, second pure water and third pure water cleanings.

5. The wafer cleaning process of claim 1, wherein: The drying treatment includes: Rotating the wafer and blowing dry the wafer with nitrogen.

6. The wafer cleaning process of claim 5, wherein: During the drying treatment, the temperature of the nitrogen is 28-35℃, the drying time is 270-320 seconds, the wafer is in a rotating state, and the rotation rate is 150-200 revolutions per minute.

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