A device for collecting metal ions on the surface of a silicon wafer

Abstract

The embodiment of the present application discloses a collecting device for metal ions on the surface of a silicon wafer, which comprises a collecting module capable of sucking a set volume of scanning liquid to collect metal ions on the surface of the silicon wafer and measure the standard content of the metal ions in the scanning liquid; a solution cavity in communication with the collecting module, capable of storing the scanning liquid for collecting metal ions on the surface of the silicon wafer and measuring the standard content of the metal ions in the scanning liquid, or for measuring the standard content of the metal ions in the scanning liquid; and a switch module arranged in the direction in which the scanning liquid is sucked and located downstream of the solution cavity, used for controlling the collecting module to suck or spray the scanning liquid.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer detection technology, and more particularly to a device for collecting metal ions on the surface of silicon wafers. Background Technology

[0002] Silicon wafers are produced by using the Magnetic Field Czochralski Method (MCZ) to obtain single-crystal silicon rods, which are then processed through wire cutting, grinding, polishing, and cleaning. During silicon wafer processing, various metallic impurities can contaminate the wafers, leading to failures in subsequent components. Light metals (such as Na, Mg, Al, K, and Ca) can cause component breakdown and voltage reduction, while heavy metals (such as Cr, Mn, Fe, Ni, Cu, and Zn) can reduce component lifespan. As the raw material for components, the surface metal ion content of silicon wafers directly affects the component yield. Therefore, it is necessary to test and control the metal ion content on the surface and edges of silicon wafers to below certain specifications to meet the requirements of subsequent processes.

[0003] Currently, when detecting metal ions on the surface of silicon wafers, a certain volume of scanning liquid is first drawn from the scanning liquid pool using a collection tube to obtain a standard value for the metal ions in the scanning liquid. Then, the same volume of scanning liquid is drawn from the collection tube and rolled on the silicon wafer surface to collect the metal ions. The metal ion content in the collected scanning liquid is then measured, and the difference between this and the standard value is used to determine the metal ion content on the silicon wafer surface. However, in practice, to avoid contamination of the scanning liquid by metal ions from the external environment, the scanning liquid in the pool is kept in a flowing state. This results in the scanning liquid used to measure the standard content of metal ions in the scanning liquid and the content of metal ions to be measured on the silicon wafer surface being solutions from different times, affecting the accuracy of the measurement results. Summary of the Invention

[0004] In view of this, embodiments of the present invention aim to provide a device for collecting metal ions on the surface of silicon wafers, which can improve the measurement accuracy of metal ion content on the surface of silicon wafers.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a device for collecting metal ions on the surface of a silicon wafer, the device comprising:

[0007] The acquisition module is capable of drawing a set volume of scanning liquid to collect metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning liquid.

[0008] A solution chamber connected to the acquisition module is provided, which can store the scanning liquid for collecting metal ions on the silicon wafer surface and measuring the standard content of metal ions in the scanning liquid, or for measuring the standard content of metal ions in the scanning liquid.

[0009] A switch module is disposed in the direction in which the scanning liquid is drawn and located downstream of the solution chamber. The switch module is used to control the acquisition module to draw in or spray the scanning liquid.

[0010] This invention provides a device for collecting metal ions on the surface of silicon wafers. The device uses a collection module to draw scanning liquid to collect metal ions on the surface of silicon wafers, and at the same time, it draws the same volume of scanning liquid to measure the standard content of metal ions in the scanning liquid. That is, it uses scanning liquid in the same state to measure the content of metal ions to be measured on the surface of silicon wafers and the standard content of metal ions in the scanning liquid. The measurement results are highly accurate and have small errors. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of a collector scanning the surface and edges of a silicon wafer in a conventional technical solution;

[0012] Figure 2 This is a schematic diagram of a device for collecting metal ions on the surface of a silicon wafer, provided in an embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram of another device for collecting metal ions on the surface of a silicon wafer, provided in an embodiment of the present invention. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0015] In related technologies, to achieve the testing of trace metal ion content in silicon wafers, two devices are required: vapor phase decomposition (VPD) and inductively coupled plasma mass spectrometry (ICP-MS). These devices are used to perform quantitative ion analysis on the collected VPD liquid. The general steps include:

[0016] S1. The silicon wafer is transferred to the VPD etching tank by a robotic arm. At the same time, HF solution vapor is introduced into the VPD etching tank for 2-5 minutes to remove the oxide film on the surface of the silicon wafer, so that the metal ions in the film are free on the surface of the silicon wafer. Generally speaking, a very thin silicon dioxide film will appear on the surface of the silicon wafer and the surface of the silicon wafer after heating. Using hydrofluoric acid vapor as a cleaning agent, the silicon dioxide film with a thickness of about 10 angstroms is enough to be dissolved by 38% high-purity hydrofluoric acid within 5 minutes. At the same time, after the silicon wafer is cleaned by hydrofluoric acid, the outermost Si layer on the surface of the silicon wafer is almost terminated by H bonds, and the surface is hydrophobic, which is conducive to the rolling of VPD droplets on the surface of the silicon wafer and will not form tails or residues on the surface of the silicon wafer, thus ensuring the integrity of VPD droplet collection.

[0017] S2. On the scanning platform of the ICP-MS equipment, 1 ml of VPD liquid droplets are drawn through the nozzle of the surface metal collection system and rolled on the surface of the silicon wafer or the edge of the silicon wafer to collect the metal components on the surface of the silicon wafer.

[0018] S3. After atomizing the VPD droplets containing metal components, perform spectral analysis to test the metal content in the recovered liquid. Subtract the metal content in the VPD droplets from the metal content in the recovered liquid to calculate the content of various metal ions on the silicon wafer surface.

[0019] See Figure 1 This illustrates a schematic diagram of a collector 1 scanning the surface and edges of a silicon wafer W in a related art. (See diagram for example.) Figure 1 As shown, the sampler 1 mainly includes: an injection pump 11, a vacuum tube 12, an outer nozzle 13, an inner nozzle 14, a sealing plug 15, a valve 16, a vacuum pump 17, and an edge support 18. The robotic arm places the back side of the silicon wafer W (with its surface oxide film removed) onto a perforated stage and adsorbs the back side of the silicon wafer W onto the surface of the stage. The robotic arm drives the bottom of the scanning outer nozzle 13 in the sampling device 1 to maintain a suitable distance from the surface of the silicon wafer W. The injection pump 11 injects the scanning liquid Dro into the cavity between the inner nozzle 14 and the outer nozzle 13. The vacuum pump 17 extracts air from the cavity between the inner nozzle 14 and the outer nozzle 13 to provide a constant vacuum. When the weight of the scanning liquid Dro is balanced with the vacuum level in the cavity between the inner nozzle 14 and the outer nozzle 13, the vacuum pump 17 stops extracting air. At this point, a portion of the scanning liquid Dro drips into the cavity between the inner and outer nozzles, while the other portion automatically floats outside the cavity to facilitate contact with the surface of the silicon wafer W for scanning. Finally, following the set scanning route, the position of the scanning robotic arm is adjusted so that the scanning liquid Dro drips onto different areas such as the surface and edges of the silicon wafer W, and the scanning liquid Dro rolls on the surface and edges of the silicon wafer W to collect the metal components on the surface and edges of the silicon wafer W, such as... Figure 1 As shown in A, the scanning liquid Dro scans the surface of the silicon wafer, and as shown in Figure 1. Figure 1 As shown in B, the scanning liquid Dro scans the edge of the silicon wafer.

[0020] However, in the process of collecting metal ions from the silicon wafer surface, it is necessary to first draw a certain volume of scanning liquid from the scanning liquid pool to measure and obtain the standard content of metal ions in the scanning liquid. Then, the same volume of scanning liquid is drawn and rolled on the silicon wafer surface to collect metal ions. The analyte content of metal ions in the collected scanning liquid is detected, and the difference between this and the original metal ion content is used to obtain the metal ion content on the silicon wafer surface. However, in actual implementation, to avoid metal ions from the external environment entering the scanning liquid pool and contaminating it, the scanning liquid in the scanning liquid pool is in a flowing state. This results in the solution used to measure the standard content of metal ions in the scanning liquid and the solution used to collect the metal ion content on the silicon wafer surface being scanning liquids from different times, affecting the accuracy of the measurement results.

[0021] Based on the above explanation, see Figure 2 This invention provides a device 2 for collecting metal ions on the surface of a silicon wafer, the device 2 comprising:

[0022] The acquisition module 10 is capable of absorbing a set volume of scanning liquid Dro to collect metal ions on the surface of the silicon wafer and to measure the standard content of metal ions in the scanning liquid Dro.

[0023] The solution chamber 20 is connected to the acquisition module 10. The solution chamber 20 can store the scanning liquid Dro for collecting metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning liquid Dro, or for measuring the standard content of metal ions in the scanning liquid Dro.

[0024] A switch module 30 is disposed in the direction in which the scanning fluid Dro is drawn and located downstream of the solution chamber 20. The switch module 30 is used to control the acquisition module 10 to draw or spray the scanning fluid Dro.

[0025] for Figure 2 The acquisition device 2 shown uses the acquisition module 10 to absorb scanning liquid Dro to collect metal ions on the silicon wafer surface. At the same time, the acquisition module 10 absorbs the same volume of scanning liquid to measure the standard content of metal ions in the scanning liquid. That is, it uses scanning liquid in the same state to measure the content of metal ions to be measured on the silicon wafer surface and the standard content of metal ions in the scanning liquid. The measurement results are highly accurate and have small errors.

[0026] for Figure 2 The data acquisition device 2 shown, in some possible implementations, such as Figure 2 As shown, a nozzle 40 is provided at one end of the acquisition module 10, and the nozzle 40 is configured to quantitatively absorb or spray the scanning liquid Dro.

[0027] for Figure 2 In some possible embodiments of the acquisition device 2 shown, the sidewall of the solution chamber 20 is provided with scale lines 201 to control the volume of the scanning liquid Dro.

[0028] for Figure 2 In some possible embodiments, the scanning solution Dro in the sampling device 2 shown is composed of: HF with a mass fraction of 0.264% to 3%, H2O2 with a mass fraction of 4% to 11.42%, and the remainder being H2O. Specifically, the hydrogen peroxide (H2O2) has a mass concentration of 35±1% and is of AA-10 purity from Tama Chemical, Japan; the hydrofluoric acid (HF) has a mass concentration of 38% and is of AA-10 purity from Tama Chemical, Japan; and the ultrapure water has a resistivity ≥18 MΩ·cm, a water quality of resistivity >18.2 MΩ·cm, and a TOC <5 ppb.

[0029] for Figure 2 In some possible embodiments, the acquisition device 2 shown may further include a power unit 50 connected to the other end of the acquisition module 10, the power unit 50 being used to provide power for the acquisition module 10 to draw the scanning fluid Dro.

[0030] Understandably, such as Figure 2 As shown, when the unit switch 30 is turned on, the power unit 50 applies power, causing the collection tube 102 to draw a set volume of scanning liquid Dro from the scanning liquid pool, for example, 2 ml, and place the 2 ml of scanning liquid into the solution chamber 20; at the same time, the control switch unit 30 drips 1 ml of scanning liquid Dro in the solution chamber 20 into a set container along the collection tube 10 to measure the standard content of metal ions in the scanning liquid; subsequently, the control switch unit 30 gathers the remaining 1 ml of scanning liquid in the solution chamber 20 along the collection tube 10 to the nozzle 40 to collect and measure metal ions on the silicon wafer surface.

[0031] Based on this, for Figure 2 The acquisition device 2 shown, in some examples, such as Figure 2 As shown, the acquisition module 10 contains only one first acquisition tube 101. The first acquisition tube 101 can draw a set volume of scanning liquid Dro to collect metal ions on the surface of the silicon wafer and measure the standard content of metal ions in the scanning liquid Dro.

[0032] Furthermore, the scanning liquid Dro stored in the solution chamber 20 is used to collect metal ions on the surface of the silicon wafer and to measure the standard content of metal ions in the scanning liquid Dro.

[0033] In addition, for Figure 2The acquisition device 2 shown, in some examples, such as Figure 3 As shown, the acquisition module 10 includes a first acquisition tube 101 and a second acquisition tube 102; wherein, the scanning liquid Dro absorbed by the first acquisition tube 101 is used to measure the standard content of metal ions in the scanning liquid Dro, and the scanning liquid Dro absorbed by the second acquisition tube 102 is used to collect metal ions on the surface of the silicon wafer.

[0034] Furthermore, the solution chamber 20 is only located on the first collection tube 101;

[0035] Furthermore, both the first acquisition tube 101 and the second acquisition tube 102 are provided with a switch unit 30.

[0036] In the above example, in the specific implementation process, the length of the second acquisition tube 102 is greater than the length of the first acquisition tube 101.

[0037] Specifically, the acquisition device 2 includes a first acquisition tube 101 and a second acquisition tube 102, both of which are connected to the power unit 50. The first acquisition tube 101 has a built-in solution chamber 20. In addition, the first acquisition tube 101 and the second acquisition tube 102 are each equipped with corresponding switch units 30-A and 30-B. In the specific implementation process, the switch units 30-A and 30-B are controlled to allow the first acquisition tube 101 and the second acquisition tube 102 to simultaneously draw a set volume of scanning liquid Dro from the scanning liquid pool, for example, drawing 1 ml of scanning liquid Dro. The scanning liquid Dro in the second acquisition tube 102 is collected at the nozzle 40 to collect metal ions on the silicon wafer surface, and the scanning liquid Dro in the first acquisition tube 101 is drawn in and contained in the built-in solution chamber 20. After collecting metal ions on the silicon wafer surface using the scanning liquid Dro in the second collection tube 102, the standard content of metal ions is measured using the scanning liquid Dro contained in the solution chamber 20 in the first collection tube 101. The metal ion content on the silicon wafer surface is then calculated by subtracting the two measurement results.

[0038] Understandably, the length of the second collection tube 102 being greater than the length of the first collection tube 101 can prevent the first collection tube 101 from interfering with the second collection tube 102 when it collects metal ions on the silicon wafer surface.

[0039] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for collecting metal ions on the surface of a silicon wafer, characterized in that, The data acquisition device includes: The acquisition module is capable of drawing a set volume of scanning liquid to collect metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning liquid. A solution chamber connected to the acquisition module is provided, which can store the scanning liquid for collecting metal ions on the silicon wafer surface and measuring the standard content of metal ions in the scanning liquid, or for measuring the standard content of metal ions in the scanning liquid. A switch module, positioned in the direction in which the scanning liquid is drawn and located downstream of the solution chamber, is used to control the acquisition module to draw in or eject the scanning liquid. The acquisition module includes a first acquisition tube and a second acquisition tube; wherein the scanning liquid drawn by the first acquisition tube is used to measure the standard content of metal ions in the scanning liquid, and the scanning liquid drawn by the second acquisition tube is used to collect metal ions on the surface of the silicon wafer; Furthermore, the solution chamber is located only on the first collection tube; Furthermore, both the first and second acquisition tubes are equipped with a switching unit. The length of the second acquisition tube is greater than the length of the first acquisition tube.

2. The data acquisition device according to claim 1, characterized in that, One end of the acquisition module is provided with a nozzle, which is configured to quantitatively absorb or spray the scanning liquid.

3. The data acquisition device according to claim 1, characterized in that, The sidewall of the solution chamber is provided with graduation lines to control the volume of the scanning liquid.

4. The data acquisition device according to claim 1, characterized in that, The scanning solution consists of 0.264% to 3% HF by mass, 4% to 11.42% H2O2 by mass, and the remainder being H2O.

5. The data acquisition device according to claim 1, characterized in that, The acquisition device also includes a power unit connected to the other end of the acquisition module, the power unit being used to provide power for the acquisition module to draw the scanning fluid.

6. The data acquisition device according to any one of claims 1 to 5, characterized in that, The acquisition module contains only one first acquisition tube, which can draw a set volume of scanning liquid to collect metal ions on the surface of the silicon wafer and measure the standard content of metal ions in the scanning liquid. Furthermore, the scanning liquid stored in the solution chamber is used to collect metal ions on the surface of the silicon wafer and to measure the standard content of metal ions in the scanning liquid.

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