Method for preventing crystallization of tilting tray recovery tray

Abstract

The invention relates to a method for preventing crystallization of a recovery disc with a swash plate surface, which aims at the recovery disc with the swash plate surface, and the swash plate surface can improve the parabola starting point for throwing out liquid medicine, so that the throwing-out distance of the liquid medicine is increased, the influence of factors such as friction force between the liquid medicine and the disc surface and the surface tension of the liquid medicine is reduced, and the recovery efficiency of the liquid medicine is improved. According to the cleaning method, it is guaranteed that the positions, prone to crystallization, on the recovery disc can be thoroughly cleaned through rotation speed matching of the recovery disc and the wafer bearing table, in the first step, the wafer rotation speed A1 is smaller than the rotation speed B1 of the recovery disc, and in the second step, deionized water is movably sprayed from the center of the wafer to the edge of the wafer through a nozzle at the tail end of a deionized water swing arm. The rotating speed A2 of the wafer is larger than the rotating speed B2 of the recovery disc, and the rotating speed A3 of the wafer in the step 3 is smaller than the rotating speed B3 of the recovery disc again. The recovery disc can be prevented from crystallization for a long time while it is guaranteed that the recovery efficiency of the liquid medicine is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and more specifically to a method for preventing crystallization on a tilted disk recovery plate. Background Technology

[0002] Wet etching is widely used in semiconductor manufacturing processes, and the recovery of etching solutions is crucial. A common method in existing technologies is to use a recovery tray for solution recovery. For example, patent CN115999823A discloses a fluid speed control device, which includes a substrate rotating shaft and a fluid recovery tray. During the process, the wafer is placed on the substrate at the upper end of the substrate rotating shaft, and the etching solution on the substrate flows to the fluid recovery tray below. The fluid recovery tray rotates at a higher speed than the substrate, allowing it to effectively eject the liquid onto the substrate into an outer recovery chamber. This fluid recovery tray structure improves the solution recovery efficiency; tests have shown that the solution recovery rate using this method is generally between 95% and 98%.

[0003] However, existing fluid recovery trays have the following problems: First, a small amount of liquid medicine still remains on the fluid recovery tray. If it is not cleaned in a timely and effective manner, it will gradually crystallize, which will affect the cavity environment, increase maintenance difficulty and risk. If two or more liquid medicines are involved, there is also a risk of mixing. Therefore, the cleaning frequency of existing fluid recovery trays is relatively high, and crystals usually appear on the recovery tray after 2 to 3 weeks of use. Second, although the liquid medicine recovery rate of existing fluid recovery trays can reach 95% to 98%, there is still some liquid medicine loss. The lost liquid medicine is mainly due to the friction between the liquid medicine and the tray surface and the surface tension of the liquid medicine, which prevents some liquid medicine from being thrown into the recovery cavity, but instead flows into the gap between the tray surface and the recovery cavity. Therefore, how to further improve the liquid medicine recovery efficiency is also a problem that needs to be considered. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preventing crystallization on an inclined recovery plate. The method involves setting an inclined plate on the surface of the recovery plate to increase the distance the liquid is thrown out, thereby improving the recovery efficiency. At the same time, the rotation speed of the recovery plate and the substrate stage are coordinated to ensure that the easily crystallized areas on the recovery plate are thoroughly cleaned. In this way, while improving the recovery efficiency, the recovery plate can also be kept free from crystallization for a long time.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preventing crystallization on an inclined recovery plate includes a recovery plate and a plate-holding platform that rotate independently. The plate-holding platform has an adjustable deionized water swing arm and a nitrogen swing arm on its upper side and a back spray nozzle on its lower side. The recovery plate has an inclined surface that is higher on the outside and lower on the inside, and the angle α between the inclined surface and the horizontal direction is 2–10°. The method for preventing crystallization on the inclined recovery plate includes the following steps:

[0007] Step 1: Place the wafer on the wafer support stage. After spraying the chemical solution, first use the nozzle at the end of the deionized water swing arm to spray deionized water at a fixed point in the center of the wafer. At this time, the wafer support stage drives the wafer to rotate at a speed of A1, the recovery tray rotates at a speed of B1, and the spraying time is T1, where A1 < B1.

[0008] Step 2: Use the nozzle at the end of the deionized water swing arm to spray deionized water from the center of the wafer to the edge of the wafer. At the same time, turn on the back spray nozzle to spray water. At this time, the wafer stage drives the wafer rotation speed to increase from A1 to A2, and the recovery tray rotation speed increases from B1 to B2. The spraying time is T2, where A2 > B2.

[0009] Step 3: Keep the nozzle at the end of the deionized water swing arm moving from the center of the wafer to the edge of the wafer to spray deionized water, while keeping the back spray nozzle spraying water. Reduce the rotation speed of the wafer carried by the wafer stage from A2 to A3, and increase the rotation speed of the recovery tray from B2 to B3. The spraying time is T3, where A3 < B3.

[0010] Step 4: The deionized water swing arm and the back spray nozzle both stop spraying water. The wafer stage drives the wafer rotation speed to increase from A3 to A4, and the rotary table rotation speed to decrease from B3 to B4. The nitrogen nozzle at the end of the nitrogen swing arm sprays nitrogen onto the front side of the wafer for a time of T4, where A4 > B4.

[0011] In step two, the nozzle at the end of the deionized water swing arm moves from the center of the wafer to the edge of the wafer to spray deionized water, and the outermost position of the spray is 0-5mm away from the edge of the wafer.

[0012] In step two, the wafer rotation speed A2 ranges from 500 to 1000 rpm.

[0013] In step three, the wafer rotation speed A3 ranges from 100 to 180 rpm.

[0014] In step four, the wafer rotation speed A4 ranges from 1000 to 2000 rpm.

[0015] The advantages and positive effects of this invention are as follows:

[0016] 1. This invention replaces the existing flat recovery tray with a recovery tray structure featuring an inclined surface. The inclined surface is higher on the outside and lower on the inside, with an angle α of 2–10° to the horizontal. This invention provides an upward-angled throwing force to the liquid medicine on the recovery tray, thus increasing the parabolic starting point of the liquid medicine's throw. This increases the throwing distance of the liquid medicine while reducing the friction between the liquid medicine and the tray surface, as well as the influence of surface tension. This prevents the liquid medicine from flowing into the gap between the tray surface and the recovery chamber, thereby improving the liquid medicine recovery efficiency. Tests show that the liquid medicine recovery rate of the recovery tray after the structural modification of this invention can be increased to over 99%.

[0017] 2. This invention utilizes the coordinated rotation speeds of the recovery tray and the wafer stage to ensure thorough cleaning of easily crystallized areas on the recovery tray. In step one, the wafer rotation speed A1 < the recovery tray rotation speed B1. In step two, the nozzle at the end of the deionized water swing arm sprays deionized water from the wafer center to the wafer edge, while the back spray nozzle is activated. Furthermore, the wafer rotation speed A2 > the recovery tray rotation speed B2, allowing the deionized water to flow back a certain distance along the back of the wafer towards the wafer center and clean the easily crystallized areas on the recovery tray. In step three, the wafer rotation speed A3 < the recovery tray rotation speed B3. By reducing the wafer rotation speed, more deionized water is sprayed onto the back of the wafer and bounces back onto the recovery tray, and this water is closer to the center of the recovery tray, further ensuring the cleaning of easily crystallized areas on the recovery tray.

[0018] 3. This invention does not require modification to the equipment structure. It can prevent crystallization by controlling the rotation speed of the recovery tray and the substrate receiving platform. This also makes it possible to use such a recovery tray with an inclined surface to improve the efficiency of drug recovery.

[0019] 4. In addition to being applicable to recycling trays with inclined surfaces, the method of the present invention is also applicable to conventional recycling trays with flat surfaces. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the device of the present invention.

[0021] Figure 2 for Figure 1 Top view of the device in the middle.

[0022] Figure 3 This is a schematic diagram of the working state of the method of the present invention. Figure 1 ,

[0023] Figure 4 This is a schematic diagram of the working state of the method of the present invention. Figure 2 ,

[0024] Figure 5 This is a schematic diagram of the process of the method of the present invention.

[0025] Figure 6 This is a schematic diagram showing the location where the rotating disk is prone to crystallization in the prior art.

[0026] Among them, 1 is the recovery tray, 101 is the inclined tray surface, 102 is the easily crystallized area, 2 is the wafer support stage, 3 is the back spray water nozzle, 4 is the deionized water swing arm, 5 is the chemical solution, 6 is the chemical solution recovery chamber, 7 is the nitrogen swing arm, and 8 is the wafer. Detailed Implementation

[0027] The invention will now be described in further detail with reference to the accompanying drawings.

[0028] like Figures 1-2 As shown, the device of the present invention includes a recovery tray 1, a substrate support 2, and a liquid medicine recovery chamber 6. The recovery tray 1 and the substrate support 2 are driven to rotate by different driving devices, which is a well-known technology in the field. For example, see the driving of the fluid recovery tray and the substrate rotating shaft in patent CN115999823A. When the device is working, the liquid medicine 5 on the substrate support 2 first flows to the recovery tray 1 below, and then is thrown out into the liquid medicine recovery chamber 6 by the rotation of the recovery tray 1. The substrate support 2 is provided with a deionized water swing arm 4 and a nitrogen swing arm 7 with adjustable positions on the upper side, and a back spray nozzle 3 on the lower side. The deionized water swing arm 4 and the back spray nozzle 3 are both well-known technologies in the field. The deionized water swing arm 4 and the nitrogen swing arm 7 can be driven to swing by a motor or other device to adjust the position of the end nozzle.

[0029] like Figure 1 As shown, this invention firstly improves the structure of the recovery disc 1 to enhance the efficiency of liquid drug recovery. The existing flat recovery disc is replaced with a recovery disc 1 structure featuring an inclined disc surface 101. The inclined disc surface 101 is higher on the outside and lower on the inside, with an angle α of 2–10° to the horizontal direction. This inclined disc surface 101 provides an upward-angled throwing force to the liquid drug on the recovery disc 1, thus increasing the parabolic starting point of the liquid drug's trajectory. This increases the throwing distance while reducing the friction between the liquid drug and the disc surface, as well as the surface tension of the liquid drug. This prevents the liquid drug from flowing into the gap between the disc surface and the recovery chamber, thereby improving the recovery efficiency. Furthermore, the angle α should not be too large; an excessively large angle only increases the throwing height but not the throwing distance. Testing shows that the liquid drug recovery rate of the recovery disc 1 after this structural modification can be increased to over 99%.

[0030] However, after the surface of the recovery disc 1 is changed, the inclined disc surface 101 makes the middle of the recovery disc 1 concave, which makes it easier for the liquid medicine to remain in the concave area, and the residue is deeper. In the prior art, the recovery disc with a flat surface will generally crystallize after 2 to 3 weeks of use and cannot be cleaned. Although the recovery disc 1 with the inclined disc surface 101 of the present invention can increase the distance of liquid medicine being thrown out and improve the efficiency of liquid medicine recovery, the liquid medicine is more likely to remain, which greatly shortens the time for crystallization to occur and greatly increases the cleaning frequency and difficulty. This is very unfavorable to the promotion and application of the recovery disc 1.

[0031] In order to thoroughly clean the areas of the recovery tray 1 that are prone to crystallization, the rotational speed of the recovery tray 1 and the substrate stage 2 have been redesigned in this invention.

[0032] The method of the present invention includes the following steps:

[0033] Step 1: Place the wafer on the wafer stage 2. After spraying the chemical solution, first... Figure 3 As shown, deionized water is sprayed at a fixed point in the center of wafer 8 using the nozzle at the end of the deionized water swing arm 4. At this time, the wafer stage 2 drives the wafer to rotate at a speed of A1 = 300 rpm, the recovery tray 1 rotates at a speed of B1 = 320 rpm, and the spraying time is T1 = 10 seconds.

[0034] In this step, A1 < B1.

[0035] Step 2: Using the nozzle at the end of the deionized water swing arm 4, deionized water is sprayed from the center of wafer 8 to the edge of wafer 8. At the same time, the back spray nozzle 3 is turned on to spray water. At this time, the wafer stage 2 drives the wafer rotation speed to A2 = 800 rpm, the recovery tray 1 rotation speed increases to B2 = 450 rpm, the back spray water flow rate is C = 350 ml / min, and the spraying time is T2 = 20 seconds.

[0036] In this step, the nozzle at the end of the deionized water swing arm 4 first moves from the center of wafer 8 to the edge of wafer 8 to spray deionized water. The outermost spray position is 0-5mm away from the edge of wafer 8. The closer the spray position is to the edge of wafer 8, the more effectively it can clean the crystallized area of ​​the recovery tray 1, because... Figure 3 As shown, the liquid is sprayed close to the center of wafer 8, and the ejection point of liquid 5 is relatively far from the edge of wafer 8, while... Figure 4 As shown, the liquid is sprayed close to the edge of wafer 8. The spraying position of the liquid 5 is relatively close to the edge of wafer 8. The closer it is to the edge of wafer 8, the less kinetic energy the sprayed deionized water gains from the rotation of wafer 8. Under the influence of factors such as the surface tension of the plasma water, the plasma water can flow back a certain distance along the back of wafer 8 towards the center of wafer 8, thus cleaning the crystallized area of ​​the recovery tray 1 more effectively. Figure 6 As shown, the easily crystallizing region 102 on the existing rotary table 1 is usually L = 7 cm away from the edge of the substrate 2.

[0037] In this step, A2 > B2. The high-speed water washing of the wafer stage 2 quickly removes the chemical solution from the surface of the wafer 8. At the same time, the rotation speed of the rotary table 1 is much lower than that of the wafer stage 2 to ensure that the deionized water on the front side can flow back along the back side of the wafer and clean the chemical solution residue on the recovery tray 1 that is prone to crystallization.

[0038] In this step, the wafer rotation speed A2, the recovery tray 1 rotation speed B2, the back spray water flow rate C1, and the spraying time T2 can be set according to actual needs. The wafer rotation speed A2 ranges from 500 to 1000 rpm, the recovery tray 1 rotation speed B2 ranges from 300 to 600 rpm, the front deionized water flow rate ranges from 600 to 1200 ml / min, the back spray water flow rate ranges from 300 to 500 ml / min, and the spraying time T2 is 20 to 60 seconds.

[0039] Step 3: Keep the nozzle at the end of the deionized water swing arm 4 moving from the center of the wafer to the edge of the wafer to spray deionized water, while keeping the back spray nozzle 3 spraying water. The wafer stage 2 drives the wafer speed to decrease to A3 = 120 rpm, and the speed of the recovery tray 1 increases to B3 = 500 rpm. The spraying time is T3 = 30 seconds.

[0040] In this step, A3 < B3. Reducing the wafer rotation speed allows more deionized water to be sprayed onto the back of wafer 8 and bounce back onto the recovery tray 1, and this water is also closer to the center of the recovery tray 1. The above results are obtained through experiments, and the specific experimental data are shown in Table 1 below.

[0041]

[0042] Table 1

[0043] In this step, the wafer rotation speed A3, the recovery tray 1 rotation speed B3, and the spraying time T3 can be set according to actual needs. The wafer rotation speed A3 ranges from 100 to 180 rpm, the recovery tray 1 rotation speed B3 ranges from 450 to 600 rpm, and the spraying time T3 is 20 to 60 seconds.

[0044] Step 4: The wafer is dried by high-speed, long-term rotation and nitrogen spraying on the front side of the wafer. Specifically, the deionized water swing arm 4 and the back spray nozzle 3 both stop spraying water. Then, the wafer stage 2 drives the wafer rotation speed to A4 = 2000 rpm, the rotary table 1 rotation speed is reduced to B4 = 400 rpm, and the nitrogen nozzle at the end of the nitrogen swing arm 7 sprays nitrogen on the front side of the wafer 8 at a flow rate of N = 40 L / min for a time of T4 = 60 seconds.

[0045] In this step, A4 > B4.

[0046] In this step, the wafer rotation speed A4, the recovery tray 1 rotation speed B4, and the spraying time T4 can be set according to actual needs. The wafer rotation speed A4 ranges from 1000 to 2000 rpm, the recovery tray 1 rotation speed B4 ranges from 300 to 600 rpm, and the spraying time T3 is 20 to 60 seconds.

[0047] After using the above method in this embodiment, the equipment ran continuously for 40 days. Then, the surface of the recovery tray 1 was observed and wiped, and no drug crystals were found.

[0048] In addition, in this embodiment, the method of the present invention is for a recovery tray 1 with a special structure having an inclined disk surface 101. Compared with a conventional recovery tray with a flat surface, the recovery tray 1 with this structure is more likely to accumulate liquid medicine and produce crystals. Therefore, the method of the present invention can be applied to conventional recovery tray structures.

Claims

1. A method for preventing crystallization on an inclined recovery plate, characterized in that: The system includes a recovery tray (1) and a substrate support (2) that rotate independently. The substrate support (2) has an adjustable deionized water swing arm (4) and a nitrogen swing arm (7) on its upper side and a back spray nozzle (3) on its lower side. The recovery tray (1) has an inclined surface (101) with a higher outer surface and a lower inner surface. The angle α between the inclined surface (101) and the horizontal direction is 2 to 10°. The method to prevent crystallization on the inclined surface recovery tray includes the following steps: Step 1: The wafer is placed on the wafer support stage (2). After the liquid is sprayed, deionized water is sprayed at the center of the wafer using the nozzle at the end of the deionized water swing arm (4). At this time, the wafer support stage (2) drives the wafer to rotate at a speed of A1, the recovery tray (1) rotates at a speed of B1, and the spraying time is T1, where A1 < B1. Step 2: Use the nozzle at the end of the deionized water swing arm (4) to spray deionized water from the center of the wafer to the edge of the wafer. At the same time, turn on the back spray nozzle (3) to spray water. At this time, the wafer stage (2) drives the wafer rotation speed to increase from A1 to A2, and the rotation speed of the recovery tray (1) increases from B1 to B2. The spraying time is T2, where A2 > B2. Step 3: Keep the nozzle at the end of the deionized water swing arm (4) moving from the center of the wafer to the edge of the wafer to spray deionized water, while keeping the back spray nozzle (3) spraying water. Reduce the rotation speed of the wafer driven by the wafer stage (2) from A2 to A3, and increase the rotation speed of the recovery tray (1) from B2 to B3. The spraying time is T3, where A3 < B3. Step 4: The deionized water swing arm (4) and the back spray nozzle (3) both stop spraying water. The wafer stage (2) drives the wafer rotation speed to increase from A3 to A4, and the rotation speed of the rotary table (1) decreases from B3 to B4. The nitrogen nozzle at the end of the nitrogen swing arm (7) sprays nitrogen on the front side of the wafer for a time of T4, where A4 > B4.

2. The method for preventing crystallization on an inclined recovery disk according to claim 1, characterized in that: In step two, the nozzle at the end of the deionized water swing arm (4) moves from the center of the wafer to the edge of the wafer to spray deionized water, and the outermost position of the spray is 0-5 mm away from the edge of the wafer.

3. The method for preventing crystallization on an inclined recovery disk as described in claim 1, characterized in that: In step two, the wafer rotation speed A2 ranges from 500 to 1000 rpm, and the rotation speed B2 of the recovery tray 1 ranges from 300 to 600 rpm.

4. The method for preventing crystallization on an inclined disk surface recovery disk according to claim 1, characterized in that: In step three, the wafer rotation speed A3 ranges from 100 to 180 rpm, and the rotation speed B3 of the recovery tray 1 ranges from 450 to 600 rpm.

5. The method for preventing crystallization on an inclined disk surface during recovery as described in claim 1, characterized in that: In step four, the wafer rotation speed A4 ranges from 1000 to 2000 rpm, and the rotation speed B4 of the recovery tray 1 ranges from 300 to 600 rpm.

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