A new type of etching tank suitable for semi-automatic acid etching of single crystal silicon wafers

Abstract

The utility model discloses a novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers, which relates to the technical field of etching equipment, and comprises a shell, wherein a reaction zone, a stirring zone, a heat exchange zone and an overflow zone are arranged inside the shell, and a lifting plate that moves up and down is arranged in the reaction zone, and symmetrical guide plates are arranged on the side walls of the reaction zone, and guide grooves are arranged on the symmetrical guide plates, and guide wheels located in the guide grooves are arranged on both sides of the lifting plate. The utility model discloses a novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers, which can facilitate operators to place carriers on the lifting plates, solves the problem that operators need to keep balance when placing silicon wafers in the etching tank, has the effect of saving manpower and improving stability, and at the same time, it can automatically float on the liquid surface without manual support, which improves convenience.

Description

Technical Field

[0001] The utility model relates to the technical field of corrosion equipment, and more specifically to a novel corrosion tank suitable for semi-automatic acid corrosion of single crystal silicon slices. Background Art

[0002] Monocrystalline silicon wafers play a vital role in modern science and technology and are widely used in semiconductor manufacturing, solar photovoltaic industry, sensor manufacturing, high-power electronic devices and other fields. After mechanical processing such as diamond wire cutting and grinding, the surface of the silicon wafer forms a damage layer of a certain depth and a large surface roughness due to the stress generated by the mechanical processing. Chemical etching is usually used to eliminate the surface damage layer and obtain better flatness and lower roughness. Acid etching usually uses a certain proportion of HF, HNO3, CH3COOH mixed acid solution to react chemically with the monocrystalline silicon wafer at a certain temperature.

[0003] The tanks of existing semi-automatic acid etching equipment are generally distributed as follows: pre-cleaning tank, etching tank, and post-cleaning tank. The acid etching reaction and silicon surface treatment are mainly completed in the etching tank, which is divided into the following modules: reaction zone, stirring zone, heat exchange zone, and overflow zone. The steps of semi-automatic acid etching are that the operator immerses the carrier loaded with silicon wafers in the reaction zone so that the acid in the stirring zone can immerse the silicon wafers, thereby acid etching them. There are also the following problems:

[0004] 1. When immersing the carrier in the acid solution, the operator needs to keep the carrier balanced and lower it at a uniform speed to prevent the silicon wafer from falling off the carrier. At the same time, the carrier loaded with silicon wafers has a certain weight, and repeated handling of the carrier will increase the labor intensity of the operators.

[0005] 2. Since the acid corrosion reaction is an exothermic reaction, the temperature will continue to rise under the premise of continuous operation. The existing heat exchange area is mainly cooled by adding capillaries in the stirring zone and cooling water. The cooling effect is poor and the reaction temperature cannot be effectively cooled in time.

[0006] 3. When silicon wafers react with mixed acid, they will produce some hexafluorosilicic acid and polymers of incompletely reacted silicon. These impurities float on the liquid surface and will have different degrees of impact on the mixed acid. They will also affect the flow of the mixed acid liquid and reduce the flow efficiency of the water body.

[0007] Therefore, it is necessary to propose a new type of etching tank suitable for semi-automatic single crystal silicon wafer acid etching to solve the above problems. Utility Model Content

[0008] 1. Technical issues to be solved

[0009] In view of the above problems, the utility model provides a new type of etching tank suitable for semi-automatic acid etching of single crystal silicon wafers; it has the function of providing stable support, so that the carrier loaded with silicon wafers can be steadily immersed in the mixed acid, reducing the labor intensity of the operators, and at the same time, it can cool the mixed acid in time to maintain the temperature of the mixed acid.

[0010] (II) Technical solution

[0011] In order to achieve the above-mentioned purpose, the utility model specifically adopts the following technical solutions:

[0012] A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers, comprising a shell, a reaction zone, a stirring zone, a heat exchange zone and an overflow zone are arranged inside the shell, a lifting plate that moves up and down is arranged in the reaction zone, symmetrical guide plates are arranged on the side walls of the reaction zone, guide grooves are opened on the symmetrical guide plates, guide wheels located in the guide grooves are arranged on both sides of the lifting plate, limit blocks are arranged on the top and bottom of the guide groove, a clamping groove is connected to the top of the lifting plate, and a carrier is inserted in the clamping groove;

[0013] Symmetrical baffles are arranged on both sides of the stirring zone, the bottom of the symmetrical baffles is connected to a bottom plate, a partition is arranged between the baffles, the bottom of the partition and the top of the baffle are connected to a filter plate, a side of the partition close to the carrier is connected to a nitrogen bubbling pipeline, a small air outlet hole is opened on the nitrogen bubbling pipeline, and the top of the other side of the partition is connected to an acid inlet pipeline;

[0014] An overflow hole extending into the overflow zone is provided on the side wall of the reaction zone, and a waste liquid hole is provided at the bottom of the overflow zone;

[0015] The bottom of the heat exchange area is connected with a heat exchange pipe.

[0016] Preferably, the filter plate comprises a fixed plate and a movable plate, both sides of the fixed plate are connected with sliding frames, and both ends of the movable plate are connected with sliders which move up and down in the sliding frames.

[0017] Preferably, a groove is provided at the top of the fixed plate, the top of the movable plate is connected to a support plate located at the top of the groove, a threaded column passing through the support plate is connected in the groove, the top of the threaded column is threadedly connected to a nut located at the top of the support plate, and a spring is connected between the support plate and the groove.

[0018] Preferably, the clamping groove is arranged in two layers, and the bottom edge of the carrier is located between the two layers of the clamping groove.

[0019] Compared with the prior art, the beneficial effects of the utility model are:

[0020] 1. The device is provided with a lifting plate in the reaction zone, which moves up and down along the guide groove, so as to float steadily on the surface of the mixed acid liquid, so that the operator can place the carrier on it, which solves the problem that the operator needs to keep balance when placing the silicon wafer into the corrosion tank, saves manpower and improves stability. At the same time, it can automatically float on the liquid surface without manual support, which improves convenience.

[0021] 2. This device sets the heat exchange pipe in the heat exchange area. The mixed acid after reacting with the silicon wafer will pass through the heat exchange area and cool down the mixed acid through heat exchange with the heat exchange pipe. It can cool down the hot mixed acid in time, solve the problem of untimely heat dissipation in traditional way, and improve the heat dissipation efficiency.

[0022] 3. The device sets the filter plate to be able to adjust the size of the filter holes. The size of the filter holes can be adjusted according to the usage, thereby adjusting the liquid flow through the filter holes to extend the circulation time of the liquid. At the same time, it can reduce the impact of impurities on the reaction between mixed acid and silicon wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional schematic diagram of the structure of the utility model;

[0024] Figure 2 It is a three-dimensional cross-sectional schematic diagram of the present invention when a carrier is placed on the top of the lifting plate;

[0025] Figure 3 It is a three-dimensional cross-sectional schematic diagram of the present invention when no carrier is placed on the top of the lifting plate;

[0026] Figure 4 It is a schematic diagram of the mixed acid flow in the utility model;

[0027] Figure 5 It is a three-dimensional schematic diagram of the connection structure between the fixed plate and the movable plate in the utility model.

[0028] Reference numerals:

[0029] 101. Shell; 102. Reaction zone; 103. Stirring zone; 104. Heat exchange zone; 105. Overflow zone; 106. Lifting plate; 107. Guide plate; 108. Guide groove; 109. Guide wheel; 110. Limit block; 111. Snap-in groove; 112. Carrier; 113. Baffle plate; 114. Bottom plate; 115. Partition plate; 116. Filter plate; 117. Nitrogen bubbling pipe; 118. Acid inlet pipe; 119. Heat exchange pipe; 120. Overflow hole; 121. Waste liquid hole; 122. Fixed plate; 123. Moving plate; 124. Sliding frame; 125. Sliding block; 126. Groove; 127. Support plate; 128. Threaded column; 129. Spring; 130. Nut. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] See also Figure 1-5 A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers includes a shell 101. The shell 101 is provided with four parts, namely a reaction zone 102, a stirring zone 103, a heat exchange zone 104 and an overflow zone 105. The reaction zone 102 and the heat exchange zone 104 are interconnected. The reaction zone 102 is used for the silicon wafer to contact with acid water so as to react. The lifting plate 106 is not a sealed plate and is provided with holes for the liquid on the upper and lower sides to circulate. The reaction zone 102 and the stirring zone 103 are provided inside the shell 101. 103, heat exchange area 104 and overflow area 105, characterized in that: a lifting plate 106 that moves up and down is arranged in the reaction area 102, and a through hole is arranged on the lifting plate 106 for the circulation of acid water up and down. The lifting plate 106 is made of polypropylene PP material with a density of 0.89-0.91 g / cm3, and the density of the mixed acid in the shell 101 is 1.25±0.1 g / cm3. The density difference allows the lifting plate 106 to be suspended in a standby position when there is no carrier 112, that is, floating on the liquid surface of the mixed acid. When the carrier 112 is manually placed 2, it can provide upward buoyancy, and does not require manual support, which reduces the labor intensity of the operator's hands, increases the stability of the hands, and improves the stability of the carrier placement process. Symmetrical guide plates 107 are arranged on the side walls of the reaction area 102, and guide grooves 108 are opened on the symmetrical guide plates 107. The guide wheels 109 move up and down along the guide grooves 108 on the guide plates 107, thereby driving the lifting plate 106 to be located at the top when there is no carrier 112, and to be located at the bottom of the guide grooves 108 when loaded with silicon wafers. The lifting plate 106 is provided with a plurality of guide wheels 109 on both sides. A guide wheel 109 is arranged in the guide groove 108, and limit blocks 110 are arranged at the top and bottom of the guide groove 108. The limit blocks 110 are located at the upper and lower ends of the guide groove 108, and are used to limit the up and down movement distance of the lifting plate 106. At the same time, the limit blocks 110 are arranged protrudingly, and when in contact with the lifting plate 106, they can provide stable support for it. The top of the lifting plate 106 is connected to a clamping groove 111, and a carrier 112 is inserted in the clamping groove 111. The clamping edge at the bottom of the carrier 112 is inserted into the clamping groove 111 at the top of the lifting plate 106;

[0032] refer to Figure 3 and Figure 4Symmetrical baffles 113 are arranged on both sides of the stirring zone 103, and the bottom of the symmetrical baffles 113 is connected to a bottom plate 114. The baffles 113 and the bottom plate 114 are arranged in cooperation to form a stirring zone 103 inside. The acid inlet pipe 118 can add new acid into the stirring zone 103. The nitrogen bubbling pipe 117 in the stirring zone 103 stirs the new acid and the old acid through the nitrogen bubbles sprayed out, so that the mixed acid on this side can enter the reaction zone 102 after passing through the top filter plate 116, so as to come into contact with the silicon wafer. A partition plate 115 is arranged between the baffles 113, and a filter plate 116 is connected to the bottom of the partition plate 115 and the top of the baffle 113. The filter plate 116 can be Adjustment is performed to control the size of the holes, so as to intercept impurities and control the flow rate of the mixed acid. A nitrogen bubbling pipe 117 is connected to one side of the partition plate 115 close to the carrier 112. The nitrogen bubbling pipe 117 is provided with fine air outlet holes. The nitrogen bubbling pipe 117 can spray nitrogen into the stirring zone 103. The nitrogen stirs the new acid and the old acid. The stirring effect of the nitrogen helps the acid liquid to contact the surface of the silicon wafer more evenly, making the corrosion process more uniform and avoiding local over-corrosion or insufficient corrosion, thereby improving the texturing effect and the quality of the silicon wafer. An acid inlet pipe 118 is connected to the top of the other side of the partition plate 115. The acid inlet pipe 118 is used to add new mixed acid into the stirring zone 103.

[0033] refer to Figure 3 and Figure 4 An overflow hole 120 extending into the overflow area 105 is provided on the side wall of the reaction area 102, and a waste liquid hole 121 is provided at the bottom of the overflow area 105. Specifically, when the carrier 112 loaded with silicon wafers is immersed in the reaction area 102, the mixed acid will react with the silicon wafers, thereby generating an exothermic reaction. At the same time, the mixed acid continues to flow from the filter plate 116 at the top. At this time, the liquid level in the reaction area 102 will rise, and impurities will be located on the liquid surface, and then will enter the overflow area 105 from the overflow hole 120, and finally be discharged from the waste liquid hole 121 at the bottom of the overflow area 105;

[0034] refer to Figure 3 and Figure 4 The bottom of the heat exchange area 104 is connected to a heat exchange pipe 119, which is spirally arranged and has a coolant flowing inside. The mixed acid is cooled by the coolant to achieve the effect of controlling the temperature.

[0035] Specifically, refer to Figure 5The filter plate 116 includes a fixed plate 122 and a movable plate 123. The two sides of the fixed plate 122 are connected with a sliding frame 124. The fixed plate 122 and the movable plate 123 are fitted together. By controlling the up and down position of the movable plate 123, the holes on the fixed plate 122 and the movable plate 123 can be staggered, thereby changing the area that can pass through, achieving the effect of controlling the intercepted objects. At the same time, the flow rate of the mixed acid can be controlled. When the movable plate 123 is located at the bottom, the holes on the upper surface are on the same axis as the holes of the fixed plate 122. At this time, the area that can pass through is the largest. Both ends of the movable plate 123 are connected with sliders 125 that move up and down in the sliding frame 124.

[0036] Specifically, the filter plate 116 close to the reaction zone 102 needs to have good filtering capabilities to prevent impurities from returning to the reaction zone 102 and affecting the reaction of the silicon wafer. The filter plate 116 away from the reaction zone 102 can be adjusted according to the situation. When the holes on it are small, most of the impurities will remain in the heat exchange zone 104. At the same time, the liquid flow rate is slow, which will cause more new acid to be supplied to the silicon wafer. When the holes are too large, most of the impurities will pass through the filter plate 116 and accumulate in the stirring zone 103.

[0037] Specifically, refer to Figure 5 A groove 126 is provided at the top of the fixed plate 122, and a support plate 127 located at the top of the groove 126 is connected to the top of the movable plate 123. The spring 129 pushes the support plate 127 to be tightly attached to the bottom of the nut 130, and the height of the movable plate 123 is controlled by the nut 130. A threaded column 128 passing through the support plate 127 is connected in the groove 126, and the top of the threaded column 128 is threadedly connected to the nut 130 located at the top of the support plate 127. A spring 129 is connected between the support plate 127 and the groove 126. The spring 129 is made of non-metallic material, preferably a plastic spring.

[0038] Specifically, the clamping groove 111 is provided in two layers, and the bottom edge of the carrier 112 is located between the two layers of the clamping groove 111, which can increase the stability when placed.

[0039] In this embodiment, the shell 101 is filled with mixed acid. At this time, the lifting plate 106 is located at the top of the reaction area 102. When silicon wafers need to be placed in the shell 101, multiple silicon wafers are placed on the carrier 112. A handle is provided on the top of the carrier 112, which is convenient for operators to grasp. The carrier 112 loaded with silicon wafers is placed on the lifting plate 106, so that the bottom of the carrier 112 is inserted into the two-layer clamping groove 111, which fixes the carrier 112. Then, the carrier 112 is slowly lowered until it reaches the bottom. The silicon wafers at the bottom will react with the mixed acid.

[0040] refer to Figure 5, the silicon wafer will produce an exothermic reaction after contacting the mixed acid, causing the temperature of the mixed acid to rise. At this time, the nitrogen bubbling pipe 117 sprays nitrogen to one side of the stirring zone 103, thereby causing the liquid level on this side to rise. Subsequently, the mixed acid passes through the filter plate 116 and flows into the reaction zone 102. After reacting with the silicon wafer, the mixed acid will move downward and move to the heat exchange zone 104. When contacting the heat exchange pipe 119, it will exchange heat with the coolant in the heat exchange pipe 119, thereby causing the temperature to drop. As the mixed acid moves, it will move to the top of the heat exchange zone 104 and enter the stirring zone 103 from the filter plate 116. After being filtered by the filter plate 116 at the bottom of the partition plate 115 again, it will move to the side with the nitrogen bubbling pipe 117, and after being mixed with the nitrogen sprayed from the nitrogen bubbling pipe 117, it will move back to the reaction zone 102 again.

[0041] When the silicon wafers in the reaction zone 102 react with the mixed acid, impurities will float on the liquid surface. When the liquid surface rises to contact the overflow hole 120, the mixed acid containing impurities on the liquid surface will move through the overflow hole 120 to the overflow zone 105 and be discharged from the waste liquid hole 121 at the bottom of the overflow zone 105, thereby completing the discharge of impurities. At the same time, when mixed acid is discharged, the acid inlet pipe 118 will fill new mixed acid into the stirring zone 103 to ensure that the total amount of mixed acid remains unchanged.

[0042] Although most of the impurities will float on the liquid surface and be discharged from the overflow hole 120 with the mixed acid, some impurities will move with the mixed acid in the shell 101, and the filter plate 116 can intercept them. At the same time, the filter plate 116 can control the liquid flow. When the size of the holes on the filter plate 116 needs to be adjusted, the nut 130 is rotated. When the nut 130 moves upward, the spring 129 will move upward against the support plate 127, so that the holes on the fixed plate 122 and the movable plate 123 are staggered. At this time, the area of ​​the holes will become smaller, so that the impurities and liquid flow that can pass through will become smaller.

[0043] When the silicon wafer and the mixed acid have finished reacting, the carrier 112 can be taken out through the handle. At this time, the lifting plate 106 will move upward and float on the surface because its density is lower than that of the mixed acid.

[0044] The above-mentioned implementation modes are only preferred implementation modes of the present invention, and cannot be used to limit the protection scope of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers, comprising a shell (101), wherein a reaction zone (102), a stirring zone (103), a heat exchange zone (104) and an overflow zone (105) are arranged inside the shell (101), characterized in that: A lifting plate (106) that moves up and down is arranged in the reaction zone (102), a symmetrical guide plate (107) is arranged on the side wall of the reaction zone (102), a guide groove (108) is opened on the symmetrical guide plate (107), guide wheels (109) located in the guide groove (108) are arranged on both sides of the lifting plate (106), and limit blocks (110) are arranged at the top and bottom of the guide groove (108), and a clamping groove (111) is connected to the top of the lifting plate (106), and a carrier (112) is inserted in the clamping groove (111); Symmetrical baffles (113) are arranged on both sides of the stirring zone (103), and the bottom of the symmetrical baffles (113) is connected to a bottom plate (114), a partition plate (115) is arranged between the baffles (113), and a filter plate (116) is connected to the bottom of the partition plate (115) and the top of the baffle (113), and a nitrogen bubbling pipe (117) is connected to one side of the partition plate (115) close to the carrier (112), and a small air outlet hole is opened on the nitrogen bubbling pipe (117), and the top of the other side of the partition plate (115) is connected to an acid inlet pipe (118); An overflow hole (120) extending into the overflow area (105) is provided on the side wall of the reaction area (102), and a waste liquid hole (121) is provided at the bottom of the overflow area (105); The bottom of the heat exchange area (104) is connected to a heat exchange pipe (119).

2. A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers according to claim 1, characterized in that: The filter plate (116) comprises a fixed plate (122) and a movable plate (123), wherein both sides of the fixed plate (122) are connected to a sliding frame (124), and both ends of the movable plate (123) are connected to a sliding block (125) that moves up and down in the sliding frame (124).

3. A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers according to claim 2, characterized in that: The top of the fixed plate (122) is provided with a groove (126); the top of the movable plate (123) is connected to a support plate (127) located at the top of the groove (126); a threaded column (128) penetrating the support plate (127) is connected in the groove (126); the top of the threaded column (128) is threadedly connected to a nut (130) located at the top of the support plate (127); and a spring (129) is connected between the support plate (127) and the groove (126).

4. A novel etching tank suitable for semi-automatic acid etching of single crystal silicon wafers according to claim 1, characterized in that: The clamping groove (111) is arranged in two layers, and the bottom edge of the carrier (112) is located between the two layers of the clamping groove (111).

Images