Method for testing the content of metal ions

Abstract

The application provides a metal ion content testing method, provides a regenerated wafer, forms an oxide layer on the regenerated wafer; the oxide layer on the regenerated wafer is bombarded by plasma formed by using nonpolar molecules as an ion source, so that Si-O bonds and Si-Si bonds are opened and combined with nonpolar molecules; the regenerated wafer is etched, then drops of extraction solution are rolled on the surface of the regenerated wafer, and metal components on the surface of the regenerated wafer are collected; the drops of extraction solution are analyzed by ICP-MS, and the content of metal components in the drops of extraction solution is calculated. The metal ion content testing method solves the problem of testing failure, reduces the metal ion testing cost, and improves the machine recovery efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a testing method of metal ion content. BACKGROUND

[0002] In the process of semiconductor production, the introduction of metal ions can cause the breakdown voltage of the chip to decrease, the dark current to increase and other defects, which affect the service life of the chip. Therefore, the content of metal ions will directly affect the yield of the chip, and the testing (VPD-ICPMS testing) of the content of metal ions is used by most chip manufacturers.

[0003] The testing of the content of metal ions includes four steps:

[0004] 1. The silicon wafer is placed in the VPD (chemical vapor decomposition) chamber and exposed to HF vapor to dissolve the natural oxide or thermal oxide SiO2 surface layer;

[0005] 2. The extraction liquid drop (usually 250 μL of 2% HF / 2% H2O2) is placed on the wafer, and then tilted in a carefully controlled manner so that the liquid drop "sweeps" on the wafer surface;

[0006] 3. As the extraction liquid drop moves on the wafer surface, it collects dissolved SiO2 and all contaminant metals;

[0007] 4. The extraction liquid drop is transferred from the wafer surface to the ICP-MS (inductively coupled plasma mass spectrometry) or ICP-MS / MS system for analysis.

[0008] The bare SI wafer used for testing is recycled wafer due to cost problems. When the recycled wafer is processed by the etching machine, the hydrophilic problem occurs when scanning the surface of the recycled wafer during the testing of the content of metal ions, which causes the testing to fail and seriously affects the machine recovery process.

[0009] In order to solve the above problems, a new testing method of the content of metal ions is needed. SUMMARY

[0010] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a testing method of the content of metal ions, which is used to solve the problem that the recycled wafer after being processed by the etching machine causes the hydrophilic problem when scanning the surface of the recycled wafer during the testing of the content of metal ions, which causes the testing to fail and seriously affects the machine recovery process.

[0011] To achieve the above-mentioned purposes and other related purposes, the present application provides a testing method of the content of metal ions, which comprises:

[0012] Step one, providing a regeneration wafer, forming an oxide layer on the regeneration wafer;

[0013] Step two, using a non-polar molecule as ion source to form plasma to bombard the oxide layer on the regeneration wafer, so that Si-O bond and Si-Si bond are opened and combined with the non-polar molecule;

[0014] Step three, etching the regeneration wafer, and then using an extraction droplet to roll on the surface of the regeneration wafer to collect the metal components on the surface of the regeneration wafer;

[0015] Step four, performing ICP-MS analysis on the extraction droplet to calculate the content of metal components in the extraction droplet.

[0016] Preferably, the material of the regeneration wafer in step one is silicon.

[0017] Preferably, the material of the oxide layer in step one is silicon dioxide.

[0018] Preferably, the non-polar molecule in step two is Ar.

[0019] Preferably, the method of etching the regeneration wafer in step three includes: placing the regeneration wafer in a chemical vapor deposition chamber, and then etching the oxide layer on the regeneration wafer with HF vapor.

[0020] Preferably, the extraction droplet in step three is a 90-130 μL mixed solution of H2O, H2O2 and HF.

[0021] Preferably, step three further includes using a mosquito coil thread moving mode of a scanning head with an embedded HF droplet to rotate the regeneration wafer at a set speed from the center of the regeneration wafer to extract the residual metal ions on the surface of the regeneration wafer.

[0022] Preferably, before etching the regeneration wafer in step three, it further includes: dropping a test extraction droplet on the center of the regeneration wafer; rolling the test extraction droplet on the surface of the regeneration wafer, and finally extracting the test extraction droplet for ICP-MS analysis to calculate the content of metal components in the test extraction droplet.

[0023] Preferably, when forming plasma using a non-polar molecule as ion source in step two, the pressure is 5-20 mt, the temperature is 50-65℃, the machine power is 350-500 W, and the time is 2-8 s.

[0024] As described above, the metal ion content testing method of the present application has the following beneficial effects:

[0025] The test method of the metal ion content solves the problem of test failure, reduces the cost of metal ion test, and improves the machine recovery efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flowchart of the test method of the present application is shown. DETAILED DESCRIPTION

[0027] The embodiments of the present application are illustrated by specific working examples below, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied by different specific embodiments, and various modifications or changes can be made to the details in the specification based on different views and applications without departing from the spirit of the present application.

[0028] Referring to Figure 1 The present application provides a test method of metal ion content, comprising:

[0029] Step one, providing a regenerated wafer, forming an oxide layer on the regenerated wafer;

[0030] In the embodiments of the present application, the material of the regenerated wafer in step one is silicon.

[0031] In the embodiments of the present application, the material of the oxide layer in step one is silicon dioxide.

[0032] Step two, using a nonpolar molecule as the plasma formed by ion source to bombard the oxide layer on the regenerated wafer, so that the Si-O bond and Si-Si bond are opened and combined with the nonpolar molecule, that is, the surface of the regenerated wafer is treated by a high-energy electron-containing nonpolar low-temperature plasma jet with a large relative molecular weight. On the one hand, the high-energy electron will bombard and break the Si-O bond and Si-Si bond, so that the nonpolar molecule is combined with it. The existence of the nonpolar particle cannot form a hydrogen bond with the polar water molecule, and the van der Waals force is reduced, so the surface energy of the regenerated wafer is reduced, the bonding force between the polar water molecule and the surface of the regenerated wafer is reduced, and the hydrophilicity of the surface of the regenerated wafer is reduced. On the other hand, due to the existence of the particle with large relative molecular weight, the surface of the regenerated wafer is bombarded in a short time, so that the roughness of the surface of the regenerated wafer is reduced, the contact angle of the surface of the regenerated wafer is increased, and the hydrophilicity of the surface of the regenerated wafer is reduced.

[0033] In the embodiments of the present application, the nonpolar molecule in step two is Ar.

[0034] In the embodiment of the present application, the plasma formed by using non-polar molecules as ion source in step two has a pressure of 5-20mt, a temperature of 50-65℃, a machine power of 350-500W, and a time of 2-8s.

[0035] Step three, etching the regenerated wafer, i.e. etching the material on the surface of the regenerated wafer to separate the metal components therefrom, and then using the extraction liquid to roll on the surface of the regenerated wafer to collect the metal components therefrom.

[0036] In the embodiment of the present application, the method for etching the regenerated wafer in step three includes: placing the regenerated wafer in a chemical vapor decomposition chamber, and then etching the oxide layer on the regenerated wafer by using HF vapor.

[0037] In the embodiment of the present application, the extraction liquid in step three is a 90-130μL mixed solution of H2O, H2O2 and HF.

[0038] In the embodiment of the present application, step three further includes: using a scanning head with an embedded drop of HF liquid to move in a mosquito coil thread manner, starting from the center of the regenerated wafer, rotating the regenerated wafer at a set speed, and extracting the residual metal ions on the surface of the regenerated wafer.

[0039] In the embodiment of the present application, before etching the regenerated wafer in step three, it further includes: dropping a test extraction liquid on the center of the regenerated wafer; rolling the test extraction liquid on the surface of the regenerated wafer, and finally extracting the test extraction liquid for ICP-MS analysis to calculate the content of the metal components in the test extraction liquid.

[0040] Step four, performing ICP-MS analysis on the extraction liquid to calculate the content of the metal components in the extraction liquid. Since the roughness of the surface of the regenerated wafer is reduced, the contact angle of the surface of the regenerated wafer is increased, and the hydrophilicity of the surface of the regenerated wafer is reduced, the problem of test failure is solved, the cost of metal ion test is reduced, and the machine reworking efficiency is improved.

[0041] It should be noted that the diagrams provided in the present embodiment only illustrate the basic concept of the present application in a schematic manner, and only the components related to the present application are shown in the diagrams, rather than the number, shape and size of the components when actually implemented. The actual implementation of each component may be arbitrarily changed in terms of type, number and proportion, and the layout pattern of the components may be more complex.

[0042] In summary, the metal ion content test method of the present application solves the problem of test failure, reduces the cost of metal ion test, and improves the machine reworking efficiency. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0043] The above embodiments are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any modification or change made by those skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A method for testing the content of metal ions, characterized in that, At least including: Step 1: Provide a regenerated wafer, wherein the material of the regenerated wafer is silicon, and the regenerated wafer is a hydrophilic regenerated wafer after being processed by an etching machine. An oxide layer is formed on the regenerated wafer, and the material of the oxide layer is silicon dioxide. Step 2: The oxide layer on the regenerated wafer is bombarded with plasma formed by using nonpolar molecules as an ion source. The nonpolar molecules are Ar. When using the nonpolar molecules as an ion source to form plasma, the pressure is 5-20 mt, the temperature is 50-65℃, the machine power is 350-500W, and the time is 2-8s. Step 3: Etch the regenerated wafer, and then use an extraction droplet to roll on the surface of the regenerated wafer to collect the metal components on the surface of the regenerated wafer. The extraction droplet is a 90-130 μL mixed solution of H2O, H2O2, and HF. Step 4: Perform ICP-MS analysis on the extracted droplets to calculate the metal content in the extracted droplets.

2. The method for testing metal ion content according to claim 1, characterized in that: The method for etching the regenerated wafer in step three includes: placing the regenerated wafer in a chemical vapor deposition chamber, and then using HF vapor to etch the oxide layer on the regenerated wafer.

3. The method for testing metal ion content according to claim 1, characterized in that: Step three also includes using a scanning head with a built-in HF droplet to move in a spiral motion similar to that of a mosquito coil, starting from the center of the regenerated wafer and rotating towards the regenerated wafer at a set rate to extract residual metal ions on the surface of the regenerated wafer.

4. The method for testing metal ion content according to claim 1, characterized in that: Before etching the regenerated wafer in step three, the process further includes: dropping a test extract droplet onto the center of the regenerated wafer; rolling the test extract droplet on the surface of the regenerated wafer; and finally extracting the test extract droplet for ICP-MS analysis to calculate the metal content in the test extract droplet.

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