A device and method for collecting metal ions at the edge of a silicon wafer

Abstract

This invention discloses a device and method for collecting metal ions at the edge of a silicon wafer. The device includes: a T-shaped baffle assembly, the vertical connecting part of which abuts against the edge of the silicon wafer, and the horizontal connecting part which is provided with a droplet groove filled with scanning liquid to collect metal ions at the first part of the edge of the silicon wafer by contacting the scanning liquid with the first part of the edge of the silicon wafer; and a support assembly for supporting the silicon wafer.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer detection technology, and more particularly to a device and method for collecting metal ions at the edge of a silicon wafer. 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 the failure of subsequent devices. Light metals (such as Na, Mg, Al, K, and Ca) can cause device breakdown and voltage reduction, while heavy metals (such as Cr, Mn, Fe, Ni, Cu, and Zn) can reduce device lifespan. As the raw material for devices, the surface metal ion content of silicon wafers directly affects the device yield. Therefore, it is necessary to detect 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] However, during the collection of metal ions at the edge of the silicon wafer, metal ions from both the upper and lower parts of the edge are recovered. Therefore, the metal ion content at the upper or lower part of the edge of the silicon wafer can only be obtained through mathematical calculation. This detection method results in low accuracy and large error in the detection of metal ion content at the edge of the silicon wafer. Summary of the Invention

[0004] In view of this, the present invention aims to provide a device and method for collecting metal ions at the edge of a silicon wafer; which can improve the detection accuracy and precision of metal ion content at the edge of the silicon wafer, and is simple to operate and highly reliable.

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

[0006] In a first aspect, embodiments of the present invention provide a device for collecting metal ions at the edge of a silicon wafer, the device comprising:

[0007] The T-shaped barrier assembly has a vertical connecting part that abuts against the edge of the silicon wafer, and a horizontal connecting part that is provided with a droplet groove filled with scanning liquid to collect metal ions from the first part of the edge of the silicon wafer by contacting the scanning liquid with the first part of the edge of the silicon wafer.

[0008] A support component for supporting the silicon wafer.

[0009] Secondly, embodiments of the present invention provide a method for collecting metal ions at the edge of a silicon wafer, the method being applicable to the collection device described in the first aspect, the method comprising:

[0010] The silicon wafer is lowered until its surface contacts the opening of the droplet groove;

[0011] The T-shaped partition assembly is moved so that the edge of the silicon wafer abuts against the vertical connecting portion of the T-shaped partition assembly, and the support assembly is moved to support the silicon wafer;

[0012] Metal ions from the first portion of the silicon wafer edge are collected by contacting the scanning liquid phase in the droplet tank with the first portion of the silicon wafer edge.

[0013] This invention provides a device and method for collecting metal ions from the edge of a silicon wafer. During the collection process, a first portion of the silicon wafer edge is brought into contact with the scanning liquid in a droplet tank. Simultaneously, the vertical connecting portion of a T-shaped baffle assembly abuts against the silicon wafer edge to prevent the scanning liquid in the droplet tank from flowing to a second portion of the silicon wafer edge, thereby completing the collection of metal ions from the first portion of the silicon wafer edge. The collection device provided by this invention can collect metal ions from only the first or second portion of the silicon wafer edge, offering simple operation and minimal detection error. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the collector scanning the surface and edge of the silicon wafer in the conventional technical solution provided in the embodiments of the present invention;

[0015] Figure 2 This is a schematic diagram illustrating the collection of metal ions from the edge of a silicon wafer in a conventional technical solution provided in an embodiment of the present invention.

[0016] Figure 3 A schematic diagram of a silicon wafer edge metal ion collection device provided in an embodiment of the present invention;

[0017] Figure 4 A schematic diagram of another silicon wafer edge metal ion collection device provided in an embodiment of the present invention;

[0018] Figure 5 This is a schematic flowchart of a method for collecting metal ions at the edge of a silicon wafer, provided in an embodiment of the present invention. Detailed Implementation

[0019] 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.

[0020] 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:

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 1As 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.

[0025] However, as Figure 1 As shown, when collecting metal ions from the upper part of the silicon wafer edge, the scanning liquid Dro rolls to the lower part of the silicon wafer edge. Specifically, as... Figure 2 As shown, when the scanning liquid Dro is dropped onto the upper part of the silicon wafer edge, due to the structural characteristics of the silicon wafer edge and the surface tension of the scanning liquid Dro, the scanning liquid Dro will flow to the lower part of the silicon wafer edge. This results in the collected scanning liquid Dro containing not only metal ions from the upper part of the silicon wafer edge but also metal ions from the lower part of the silicon wafer edge, affecting the detection accuracy and precision of the metal ion content at the silicon wafer edge.

[0026] Based on the above description, the present invention aims to provide a device for collecting metal ions at the edge of a silicon wafer, enabling the collection of metal ions only from the upper or lower portion of the edge of the silicon wafer W during the entire detection process, thereby improving the detection accuracy of metal ions at the edge of the silicon wafer W. See also... Figure 3 This illustration shows a silicon wafer edge metal ion collection device 3 provided in an embodiment of the present invention, the collection device 3 comprising:

[0027] T-shaped barrier assembly 31, the vertical connecting part 311 of the T-shaped barrier assembly 31 abuts against the edge of the silicon wafer W, and the horizontal connecting part 312 is provided with a droplet groove 3121 filled with scanning liquid Dro to collect metal ions of the first part 32 of the edge of the silicon wafer W by contacting the scanning liquid Dro with the first part 32 of the edge of the silicon wafer W.

[0028] Support component 33, which is used to support the silicon wafer W.

[0029] It should be noted that, in the embodiments of the present invention, the first part 32 of the edge of the silicon wafer W only represents the upper part or the lower part of the edge of the silicon wafer W, and is not limited to the edge part corresponding to the front side of the silicon wafer W or the edge part corresponding to the back side of the silicon wafer W.

[0030] for Figure 3 The acquisition device 3 shown in the diagram, during the acquisition process, brings the first portion 32 of the edge of the silicon wafer W into contact with the scanning liquid Dro in the droplet tank 3121. The surface tension of the scanning liquid Dro causes it to flow and fill the surface of the first portion 32 of the edge of the silicon wafer W. Simultaneously, the vertical connecting portion 311 of the T-shaped baffle assembly 31 abuts against the edge of the silicon wafer W to prevent the scanning liquid Dro in the droplet tank 3121 from flowing to the second portion 34 of the edge of the silicon wafer W, thereby completing the acquisition of metal ions from the first portion 32 of the edge of the silicon wafer. The acquisition device 3 provided by this embodiment can acquire metal ions from only the first portion 32 or the second portion 34 of the edge of the silicon wafer W, is simple to operate, and has a small error in the detection results.

[0031] for Figure 3 In some possible embodiments of the acquisition device 3 shown, the portion of the T-shaped barrier assembly 31 that contacts the silicon wafer W is covered with a flexible material. It is understood that covering the portion of the T-shaped barrier assembly 31 that contacts the silicon wafer W with a flexible material prevents damage to the surface and edges of the silicon wafer W during contact.

[0032] In some embodiments described above, the flexible material is further configured to prevent the scanning liquid Dro from overflowing from the first portion 32 of the silicon wafer W edge to the second portion 34 of the silicon wafer W edge. Understandably, in this embodiment of the invention, not only is the T-shaped baffle assembly used to prevent the scanning liquid Dro from overflowing, but the flexible material also creates a sealing effect to isolate the overflow of the scanning liquid Dro, thereby ensuring that the final collected scanning liquid Dro contains only metal ions from the first portion 32 of the silicon wafer W edge, thus improving the detection accuracy of metal ions at the edge of the silicon wafer W.

[0033] for Figure 3In some possible embodiments of the acquisition device 3 shown, the portion of the support component 33 that contacts the silicon wafer W is covered with a flexible material.

[0034] Specifically, in the embodiments of the present invention, the flexible material can be soluble polytetrafluoroethylene, polytetrafluoroethylene, etc.

[0035] for Figure 3 In some possible embodiments, the scanning liquid Dro of the sampling device 3 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; wherein the mass concentration of hydrogen peroxide (H2O2) is 35±1%, with a purity of AA-10 grade from Tama Chemical, Japan; the mass concentration of hydrofluoric acid (HF) is 38%, with a purity of AA-10 grade from Tama Chemical, Japan; and the ultrapure water has a resistivity ≥18 MΩ·cm, and the water quality has a resistivity >18.2 MΩ·cm and a TOC <5 ppb.

[0036] for Figure 3 The acquisition device 3 shown, in some possible implementations, such as Figure 4 As shown, the acquisition device 3 also includes a high-pressure gas nozzle 41, which is configured to spray high-pressure gas toward the position where the edge of the silicon wafer W abuts against the T-shaped barrier assembly 31, so that the scanning liquid Dro of the first part 32 of the edge of the silicon wafer W will not overflow onto the second part 34 of the edge of the silicon wafer W. To further prevent the wall scanning liquid Dro from overflowing onto the second part 34 and the upper surface of the edge of the silicon wafer W, in a specific implementation, a high-pressure gas nozzle 41 is provided above the contact point between the T-shaped barrier assembly 31 and the silicon wafer W, pointing toward the contact position between the silicon wafer W and the T-shaped barrier assembly 31.

[0037] In some embodiments described above, the high-pressure gas nozzle 41 is further configured to spray high-pressure gas along the second portion 34 of the edge of the silicon wafer W to the position where the silicon wafer W contacts the T-shaped barrier assembly 31.

[0038] In some embodiments described above, the high-pressure gas injected by the high-pressure gas nozzle 41 is nitrogen. Understandably, injecting inert gas into the contact area between the silicon wafer W and the T-shaped barrier assembly 31 not only further prevents the scanning liquid Dro from overflowing, but the inert gas nitrogen will not affect the changes in the metal ion composition of the scanning liquid Dro, meaning it will not affect the detection results.

[0039] See Figure 5This invention illustrates a method for collecting metal ions from the edge of a silicon wafer, provided by an embodiment of the present invention. The method can be applied to the collection device 3 described in the foregoing technical solution. The collection method includes:

[0040] S501, Lower the silicon wafer until the surface of the silicon wafer contacts the opening of the droplet groove;

[0041] S502. Move the T-shaped partition assembly so that the edge of the silicon wafer abuts against the vertical connecting portion of the T-shaped partition assembly, and move the support assembly to support the silicon wafer.

[0042] S503, The first part of the edge of the silicon wafer comes into contact with the scanning liquid phase in the droplet groove to collect metal ions from the first part of the edge of the silicon wafer.

[0043] Understandably, after the metal ions at the edge of silicon wafer W are collected, the scanning solution after scanning is atomized and subjected to spectral analysis to test the metal ion content in the recovered scanning solution and the metal ion content in the scanning solution before scanning; and the content of each metal ion in the recovered scanning solution is subtracted from the content of each metal ion in the scanning solution before scanning, so that the content of each metal ion at the edge of silicon wafer W can be calculated.

[0044] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0045] 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 at the edge of a silicon wafer, characterized in that, The data acquisition device includes: The T-shaped barrier assembly includes a vertical connecting part and a horizontal connecting part. The vertical connecting part abuts against the edge of the silicon wafer, and the horizontal connecting part is provided with a droplet groove filled with scanning liquid. This allows for the collection of metal ions from a first part of the silicon wafer edge by contacting the scanning liquid with the lower part of the silicon wafer edge. The vertical connecting part abuts against the edge of the silicon wafer to prevent the scanning liquid in the droplet groove from flowing to a second part of the silicon wafer edge. Support assembly, the support assembly being used to support the silicon wafer, The portion of the barrier assembly that contacts the silicon wafer is covered with a flexible material. The flexible material is also configured to prevent scanning liquid from overflowing from the first part of the silicon wafer edge to the second part of the silicon wafer edge.

2. The data acquisition device according to claim 1, characterized in that, The portion of the support assembly that contacts the silicon wafer is covered with a flexible material.

3. 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.

4. The data acquisition device according to claim 1, characterized in that, The acquisition device also includes a high-pressure gas nozzle, which is configured to spray high-pressure gas toward the position where the edge of the silicon wafer abuts against the T-shaped barrier assembly, so that the scanning liquid in the first part of the edge of the silicon wafer will not overflow to the second part of the edge of the silicon wafer.

5. The data acquisition device according to claim 4, characterized in that, The high-pressure gas nozzle is also configured to spray high-pressure gas along a second portion of the edge of the silicon wafer to the position where the silicon wafer contacts the T-shaped spacer assembly.

6. The data acquisition device according to claim 4, characterized in that, The high-pressure gas injected by the high-pressure gas nozzle is nitrogen.

7. A method for collecting metal ions from the edge of a silicon wafer, characterized in that, The acquisition method can be applied to the acquisition device according to any one of claims 1 to 6, and the acquisition method includes: The silicon wafer is lowered until its surface contacts the opening of the droplet groove; The T-shaped partition assembly is moved so that the edge of the silicon wafer abuts against the vertical connecting portion of the T-shaped partition assembly, and the support assembly is moved to support the silicon wafer. Metal ions from the first portion of the silicon wafer edge are collected by contacting the scanning liquid phase in the droplet tank with the first portion of the silicon wafer edge.

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