Etching method and etching device of monolithic cleaning machine

Abstract

The invention discloses an etching method and an etching device for a monolithic cleaning machine, and belongs to the technical field of microelectronic packaging, the etching method comprises the following steps: spraying a liquid medicine to the surface of a wafer at a first rotating speed, and diffusing the liquid medicine to the periphery under the action of centrifugal force; reducing the rotating speed of the wafer to a second rotating speed, diffusing the liquid medicine to all etching areas on the surface of the wafer in a self-flowing state, and forming a medicine film with uniform thickness; secondly, carrying out an etching reaction on the chemical film and the etching area of the wafer until the etching is completed; and finally, under the action of centrifugal force generated by the wafer, the liquid medicine is separated from the wafer. According to the principle of the etching method, by accurately controlling the rotating speed of the wafer and optimizing the distribution and reaction process of the liquid medicine on the surface of the wafer, the problem of uneven etching caused by blocking of a graphical pattern in a traditional spraying process is effectively solved, the etching precision and the overall quality are improved, and meanwhile the stability and controllability of the process are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of microelectronic packaging, in particular to an etching method and an etching device of a single-chip cleaning machine. Background Art

[0002] Metal wet etching is an important process for preparing RDL in the electronic packaging process. This process is generally to deposit a metal layer through electroplating or PVD, then use photoresist for patterning, and then use a single-wafer wet etcher to etch useless metal to prepare the required metal lines. At present, the etching method of a single-wafer etcher usually uses an automatic spray device to spray the liquid. The nozzle swings in a fan shape on the surface of the wafer driven by the swing arm, and the wafer spins under the action of the vacuum suction cup. After the liquid is sprayed on the surface of the wafer, it will be thrown to the liquid recovery CUP due to centrifugal force, and then flow into the recovery chassis for recycling.

[0003] The automatic spray device is used to spray the liquid to form a liquid film on the surface of the wafer. However, the liquid film will be unevenly dispersed on the surface of the wafer due to the different positions of the spray head spraying the liquid. Therefore, it is more complicated to control the uniformity of the wafer etching lines. In addition, when the liquid is recovered, there will be droplets remaining on the inner wall of the recovery CUP. This part of the liquid cannot be recovered, and under the action of FFU, the volatilization of the solution solvent will cause crystallization on the inner wall of the recovery CUP, which is troublesome to clean, affects the cleanliness of the cavity, and increases the maintenance cost of the machine. In addition, for the etching of patterned wafers, if the pattern has a certain height after patterning, the liquid will be blocked by the pattern under the action of centrifugal force in the automatic spray mode, and a discontinuous liquid film area will be formed on the back of the pattern. For high-density patterns, it will seriously affect the etching uniformity and form a large number of fan-shaped discontinuous areas on the wafer surface. In addition, the liquid near the centrifugal area will flush the pattern, resulting in more side etching in the near centrifugal area and less side etching in the far-away area, resulting in inconsistent etching effects, which limits the subsequent packaging process. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an etching method and an etching device for a single-wafer cleaning machine, which achieve uniform etching of the wafer by controlling the rotation speed of the wafer.

[0005] The present invention is achieved through the following technical solutions: In a first aspect, the present application proposes an etching method for a single-wafer cleaning machine, comprising the following process: Step 1: Spray the liquid medicine onto the surface of the wafer at a first rotation speed, and the liquid medicine spreads around under the action of centrifugal force; Step 2, reducing the wafer rotation speed to a second rotation speed, the chemical solution diffuses to all etching areas on the wafer surface in a self-flowing state, and forms a chemical film with uniform thickness; Step 3, the drug film and the etched area of ​​the wafer undergo an etching reaction until the etching is completed; Step 4: Under the action of the centrifugal force generated by the wafer, the drug solution is separated from the wafer.

[0006] Furthermore, in step 1, the drug liquid is sprayed onto the wafer surface along a preset arc path.

[0007] Furthermore, in step 1, the length of the arc track is 120 mm, the movement rate of the liquid medicine along the arc track is 120 mm / s, and the spraying time is less than 2 seconds.

[0008] Furthermore, the first rotation speed is 500-600 rpm.

[0009] Furthermore, in step 2, spraying of the chemical solution is stopped, and the wafer rotation speed is reduced to a second rotation speed, and the second rotation speed is less than 30 rpm.

[0010] Furthermore, in step 3, the wafer is in a stationary state, and an etching reaction occurs between the drug film and the wafer.

[0011] Furthermore, in step 4, the rotation speed of the wafer is increased to above 1000 rpm to separate the chemical solution from the wafer.

[0012] Furthermore, the rotation speed increase rate of the wafer is 500 rpm.

[0013] In a second aspect, the present application provides an etching device, which, when in operation, executes the etching method of the single-wafer cleaning machine described in any one of claims 1-8.

[0014] Further,, including an automatic spray device, a liquid recovery CUP, a chassis and a vacuum suction cup; The liquid medicine recovery CUP is arranged on the top of the chassis, the vacuum suction cup is installed in the liquid medicine recovery CUP through a rotating device, the wafer is adsorbed on the top of the vacuum suction cup, and the automatic spray device is arranged on the top of the liquid medicine recovery CUP; The automatic spraying device and the rotating device are connected to a control unit, and the control unit is used to execute the etching method of the single-wafer cleaning machine.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present application provides an etching method for a single-wafer cleaning machine, the principle of which is to optimize the distribution and reaction process of the liquid on the wafer surface by precisely controlling the rotation speed of the wafer. First, under high-speed rotation, the liquid is evenly sprayed onto the wafer surface in a columnar form, and rapidly diffused by centrifugal force to initially cover the wafer. Subsequently, by reducing the rotation speed, the liquid is promoted to form a uniform thickness of the film on the wafer surface, ensuring that the liquid can penetrate and cover all etching areas including the edge of the graphic pattern, avoiding the discontinuous area caused by the blocking of the graphic pattern. When the wafer is stationary, the film fully reacts with the wafer surface to achieve uniform etching. Finally, the rotation speed is gradually increased, and the residual liquid is completely removed by centrifugal force to ensure the uniformity and consistency of the etching effect. The advantage of this method is that through the fine control of the rotation speed, the problem of uneven etching caused by the blocking of the graphic pattern in the traditional spray process is effectively solved, the accuracy and overall quality of etching are improved, and the stability and controllability of the process are ensured at the same time, and the blocking effect of the pattern and the problem of uneven side etching are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a structural schematic diagram of the etching device of the present invention; Figure 2 This is the flow effect diagram of the liquid medicine under the centrifugal effect; Figure 3 A schematic diagram of etching a patterned wafer barrier by the automatic spray process of the present invention; Figure 4 Schematic diagram of liquid spraying in step 1 of the etching process of the present invention; Figure 5 Schematic diagram of step 2 of the etching process of the present invention; Figure 6 It is a schematic diagram of the recovery of the chemical solution in the etching process of the present invention; Figure 7 It is a schematic diagram of the liquid wetting pattern of the etching process of the present invention.

[0018] In the figure: 1. Automatic spray device; 2. Chemical solution recovery CUP; 3. Chassis; 4. Chemical solution; 5. Wafer; 6. Vacuum suction cup; 7. Graphical pattern; 8. Discontinuous area; 9. Liquid film. DETAILED DESCRIPTION In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0020] See also Figure 2 and 3 Under the automatic spraying process, the chemical solution is sprayed onto the surface of the wafer in the form of a column. At the same time, the spinning action of the wafer generates centrifugal force. Under the action of the centrifugal force, the chemical solution diffuses to the entire wafer surface and forms a chemical film 9, which chemically reacts with the area not covered by the graphic pattern 7 for etching; however, since the graphic pattern 7 has a certain height, it will form a blocking effect on the chemical solution during the flow of the chemical solution. Along the flow direction of the chemical solution, the side of the graphic pattern 7 close to the center of the wafer contacts with the chemical solution, and the graphic pattern 7 forms a blocking and diverting effect on the chemical solution. Therefore, the chemical solution cannot flow to the side of the graphic pattern 7 away from the center of the wafer, so a discontinuous area 8 is formed in this area, making the etching effects on both sides of the graphic pattern 7 inconsistent.

[0021] Based on the above problems, the present application provides an etching method for a single-wafer cleaning machine, comprising the following processes: Step 1: Spray the liquid medicine onto the surface of the wafer at a first rotation speed, and the liquid medicine spreads around under the action of centrifugal force; Step 2, reducing the wafer rotation speed to a second rotation speed, the chemical solution diffuses on the wafer surface to form a chemical film with uniform thickness, and covers the entire wafer etching area; Step 3, the wafer is subjected to etching reaction with the drug film in a static state until the etching is completed; Step 4: gradually increase the rotation speed of the wafer to separate the drug solution from the wafer under the action of centrifugal force.

[0022] In step 1, the purpose is to apply a centrifugal force to the chemical solution, and the wafer rotates at a higher first speed. At this time, the chemical solution is sprayed onto the wafer surface in a columnar form, and the centrifugal force generated by the rotation of the wafer causes the chemical solution to spread rapidly around and begin to cover the wafer surface. At this stage, the contact between the chemical solution and the wafer surface is preliminary, and the centrifugal force helps the chemical solution to be distributed quickly, but a uniform chemical film has not yet been formed. At this time, the chemical solution begins to react chemically with the area not covered by the graphical pattern, and preliminary etching is performed.

[0023] In step 2, the wafer speed is reduced. The key to this operation is to reduce the centrifugal force so that the solution can stay on the wafer surface longer, so that there is enough time to form a uniform and continuous film. The formation of the film is crucial to the uniformity of etching. It ensures that the solution can cover the entire wafer etching area, including both sides of the graphic pattern, thereby avoiding the formation of discontinuous areas. Under the coverage of the film, the chemical reaction between the solution and the wafer surface can continue until the etching is completed. Due to the uniformity of the film, the etching effect on both sides of the graphic pattern is also more consistent.

[0024] In step 4, the rotation speed of the wafer is gradually increased. As the rotation speed increases, the centrifugal force gradually increases. The purpose of this step is to use the centrifugal force to throw off the liquid medicine remaining on the surface of the wafer to achieve complete separation of the liquid medicine. By gradually increasing the rotation speed, it can be ensured that the liquid medicine is effectively removed. After the removal is completed, a uniformly etched pattern will be left on the surface of the wafer, and the etching effect on both sides of the graphical pattern will be consistent.

[0025] As the optimal technical solution of the present application, the wafer is at a first rotation speed of 500-600rpm, the drug solution is sprayed onto the wafer surface along an arc trajectory, and under the action of the centrifugal force of the wafer, the drug solution is quickly dispersed onto the wafer surface.

[0026] Furthermore, the length of the arc track is 120 mm, the movement rate of the liquid medicine along the arc track is 120 mm / s, and the spraying time is less than 2 seconds.

[0027] When the wafer rotates at a speed of 500-600 rpm, the centrifugal force generated can effectively disperse the liquid sprayed on the wafer surface quickly and evenly. Dispersion helps the liquid to quickly cover the entire surface of the wafer and avoids accumulation of liquid in local areas.

[0028] It should be noted that the main purpose of the wafer in this rotation speed range is to accelerate the dispersion of the solution, quickly form a solution film and cover the wafer, and shorten the etching time by improving the dispersion efficiency of the solution; however, the solution is pushed by centrifugal force to flow to the edge of the wafer. Due to the large centrifugal force, the uniformity of the solution film formed in this process cannot reach the optimal level. At the same time, due to the blocking effect of the graphical pattern 7, discontinuous areas 8 are easily formed, resulting in uneven and discontinuous areas of the solution film, which can be solved according to the method of step 2.

[0029] As the optimal technical solution of the present application, in step 2, the second rotation speed is less than 30 rpm, and the spraying of the chemical solution is stopped. The chemical solution on the surface of the wafer flows slowly at this rotation speed, and a chemical film of uniform thickness is formed on the surface of the wafer under the action of gravity, covering all etching areas of the wafer.

[0030] As the wafer's rotation speed decreases rapidly, the centrifugal force acting on the liquid medicine decreases, and the liquid medicine is in a self-flowing state. According to the flow principle of the liquid, the film slowly flows by itself and forms a film with a completely uniform thickness, covering the entire etching area of ​​the wafer. By controlling the rotation speed and stopping the spraying, the amount of liquid medicine is precisely controlled. After the liquid medicine forms a uniform film on the wafer surface, there will be no excess liquid medicine loss or waste, thereby improving the utilization rate of the liquid medicine and reducing production costs.

[0031] In step 3, in a static state, the drug film reacts chemically with the wafer to etch the wafer until etching is completed. During the etching process, the wafer is in a static state, so the drug film is in a stable state, thereby ensuring uniform etching of the wafer.

[0032] As the optimal technical solution of the present application, after etching is completed, the rotation speed of the wafer is gradually increased to above 1000 rpm. When the wafer rotates at high speed, a huge centrifugal force is generated on the drug film, and the drug film is separated from the wafer under this centrifugal force. Moreover, at this rotation speed, the drug liquid will not splash onto the side wall of the drug liquid recovery CUP, thereby preventing the drug liquid from crystallizing on the side wall of the drug liquid recovery CUP.

[0033] It should be noted that in this step, it is necessary to control the wafer rotation speed according to the size of the drug liquid recovery CUP, and then control the centrifugal force to achieve control of the drug liquid separation distance, while ensuring that the drug liquid and the wafer are completely separated. During the drug liquid separation process, under the initial accelerated rotation state, most of the drug liquid enters the drug liquid recovery CUP. In order to ensure the complete separation of the drug liquid, the wafer rotation speed is increased to more than 1000 rpm so that the residual drug liquid is completely separated from the wafer. At the highest speed, a small amount of drug liquid may splash onto the side wall of the drug liquid recovery CUP.

[0034] Example 1 An etching method for a single-wafer cleaning machine includes the following steps: Step 1: At 600 rpm, the liquid medicine is sprayed onto the surface of the wafer along an arc trajectory, and the liquid medicine diffuses around under the action of centrifugal force; the length of the arc trajectory is 120 mm, the movement rate of the liquid medicine along the arc trajectory is 120 mm / s, and the spraying time is 1.5 s.

[0035] Step 2: Stop spraying the solution and reduce the wafer rotation speed to 20 rpm. The solution diffuses on the wafer surface to form a uniform film that covers the entire wafer etching area. Step 3, stop the rotation of the wafer, that is, the rotation speed is 0, the chemical solution reacts chemically with the etching area of ​​the wafer, and etches the etching area until the etching is completed; Step 4: Increase the rotation speed of the wafer from 500 rpm to 1500 rpm to separate the chemical solution from the wafer and complete the etching of the wafer.

[0036] See also Figure 2 In step 1, it is necessary to ensure that the entire surface of the wafer is sprayed with the liquid, and then the wafer spin speed is reduced to stop the liquid spraying. When the wafer spins very slowly, the liquid sprayed on the wafer surface will form a layer of liquid film due to surface tension, covering the wafer surface. Since the wafer spins very slowly, the liquid film will not be thrown away under the action of centrifugal force. Controlling the spin speed can make the liquid film flatten into a uniform layer. This step takes a long time. Figure 3 As shown, the wafer spin speed is then increased, and the surface liquid film is thrown out of the wafer under the action of centrifugal force and flows into the recovery chassis for recycling. The etching liquid stays on the wafer surface, and the etching efficiency decreases as the reaction proceeds. For different products, different residence times are selected in the above step 3.

[0037] Example 2 Based on the etching method of the above-mentioned single-wafer cleaning machine, the present application also provides an etching device, which etches the wafer using the etching method of the above-mentioned single-wafer cleaning machine.

[0038] See also Figure 1 , 4 , 5 and 6, the etching device includes an automatic spraying device 1, a liquid recovery CUP 2, a chassis 3 and a vacuum suction cup 6.

[0039] The medicine liquid recovery CUP2 is arranged on the top of the chassis, and the vacuum suction cup 6 is installed in the medicine liquid recovery CUP2 through a rotating device. The rotating device is used to drive the vacuum suction cup to rotate, and the wafer is adsorbed on the top of the vacuum suction cup. The automatic spraying device 1 is arranged on the top of the medicine liquid recovery CUP2, and the automatic spraying device 1 sprays the medicine liquid onto the surface of the wafer.

[0040] The automatic spraying device 1 comprises a motor and a cantilever. The motor drives the cantilever to rotate. A drug delivery tube is arranged on the top of the cantilever. One end of the drug delivery tube is connected to the drug bin through a pump, and the other end is connected to a nozzle. The nozzle is fixed to the free end of the cantilever.

[0041] The motor, pump and rotating device are connected to the control unit. When the etching device is working, the program of the etching method of the single-wafer cleaning machine is executed in the control unit to etch the wafer.

[0042] It should be noted that Figure 1 It shows the state of the liquid splashing to the side wall of the liquid recovery CUP2. In this state, the liquid is easy to form crystals; see Figure 4-6 By adopting the method of the present application, the problems solved by the liquid medicine can be effectively improved.

[0043] The single-wafer cleaning machine etching method proposed in this application has the advantages that the puddle process can be used to achieve uniform etching on the wafer surface, and in the step of recovering the liquid medicine, due to the small centrifugal force, there is basically no liquid medicine left on the inner wall of the recovery CUP, and most of the liquid medicine is directly recovered by the recovery chassis, which improves the recovery efficiency and reduces the production cost and maintenance cost. And in the process of etching the patterned wafer, such as Figure 7 Since the liquid medicine is an infiltration pattern, it can effectively improve the barrier effect of high protrusion patterns and the problem of uneven side erosion.

[0044] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An etching method for a single-wafer cleaning machine, characterized in that: The process includes: Step 1: Spray the liquid medicine onto the surface of the wafer at a first rotation speed, and the liquid medicine spreads around under the action of centrifugal force; Step 2, reducing the wafer rotation speed to a second rotation speed, the chemical solution diffuses to all etching areas on the wafer surface in a self-flowing state, and forms a chemical film with uniform thickness; Step 3, the drug film and the etched area of ​​the wafer undergo an etching reaction until the etching is completed; Step 4: Under the action of the centrifugal force generated by the wafer, the drug solution is separated from the wafer.

2. The etching method of a single-wafer cleaning machine according to claim 1, characterized in that: In step 1, the drug liquid is sprayed onto the wafer surface along a preset arc path.

3. The etching method of a single-wafer cleaning machine according to claim 2, characterized in that: The length of the arc track in step 1 is 120 mm, the movement rate of the liquid medicine along the arc track is 120 mm / s, and the spraying time is less than 2 seconds.

4. The etching method of a single-wafer cleaning machine according to claim 1, characterized in that: The first rotation speed is 500-600 rpm.

5. The etching method of a single-wafer cleaning machine according to claim 1, characterized in that: In step 2, spraying of the chemical solution is stopped, and the wafer rotation speed is reduced to a second rotation speed, which is less than 30 rpm.

6. The etching method of a single-wafer cleaning machine according to claim 1, characterized in that: In step 3, the wafer is in a stationary state, and an etching reaction occurs between the film and the wafer.

7. The etching method of a single-wafer cleaning machine according to claim 1, characterized in that: In step 4, the rotation speed of the wafer is increased to above 1000 rpm to separate the chemical solution from the wafer.

8. The etching method of a single-wafer cleaning machine according to claim 7, characterized in that: The wafer rotation speed increase rate is 500 rpm.

9. An etching device, characterized in that: When the etching device is in operation, it executes the etching method of the single-wafer cleaning machine described in any one of claims 1-8.

10. An etching device according to claim 9, characterized in that: Including automatic spraying device, liquid recovery CUP, chassis and vacuum suction cup; The liquid medicine recovery CUP is arranged on the top of the chassis, the vacuum suction cup is installed in the liquid medicine recovery CUP through a rotating device, the wafer is adsorbed on the top of the vacuum suction cup, and the automatic spray device is arranged on the top of the liquid medicine recovery CUP; The automatic spraying device and the rotating device are connected to a control unit, and the control unit is used to execute the etching method of the single-wafer cleaning machine.

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