TWI842309B - A device for collecting metal ions on the surface of a silicon wafer - Google Patents

Abstract

The embodiment of the present invention discloses a device for collecting metal ions on the surface of a silicon wafer, the collecting device comprising: a collecting module, the collecting module being capable of absorbing a set volume of scanning fluid to collect metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning fluid; a solution chamber connected to the collecting module, the solution chamber being capable of storing the scanning fluid for collecting metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning fluid, or for measuring the standard content of metal ions in the scanning fluid; a switch module arranged in the direction in which the scanning fluid is absorbed and located downstream of the solution chamber, the switch module being used to control the collecting module to absorb or spray the scanning fluid.

Description

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

The embodiment of the present invention belongs to the field of silicon wafer detection technology, and in particular relates to a device for collecting metal ions on the surface of silicon wafers.

Silicon wafers are obtained by using the Magnetic Field Czochralski Method (MCZ) to obtain single crystal silicon rods, which are prepared by wire cutting, grinding, polishing, cleaning and other steps. Various metal impurities will be present in the silicon wafer processing process, which will lead to the failure of subsequent pipe fittings. Among them, light metals (such as Na, Mg, Al, K, Ca, etc.) will cause pipe fittings to break down and reduce voltage, and heavy metals (such as Cr, Mn, Fe, Ni, Cu, Zn, etc.) will reduce the life of pipe fittings. As the raw material of pipe fittings, the metal ion content on the surface of silicon wafers will directly affect the qualified rate of pipe fittings. Therefore, it is necessary to detect the metal ion content on the surface and edge of the silicon wafer and control it below a certain specification to meet the requirements of subsequent steps.

Currently, when detecting metal ions on the surface of a silicon wafer, it is necessary to first use a collection tube to draw a certain volume of scanning liquid from the scanning liquid pool for measurement to obtain the standard value of the metal ions in the scanning liquid, and then use the collection tube to draw the same volume of scanning liquid and roll it on the surface of the silicon wafer to collect the metal ions on the surface of the silicon wafer, and detect the metal ion content in the collected scanning liquid, and obtain the metal ion content on the surface of the silicon wafer by subtracting it from the standard value of the metal ions. However, in the specific implementation process, in order to prevent metal ions in the external environment from entering the scanning liquid pool and causing contamination to the scanning liquid, the scanning liquid in the scanning liquid pool is in a flowing state. This causes the scanning liquid used to measure the standard content of metal ions in the scanning liquid and the scanning liquid used to measure the content of metal ions on the surface of the silicon wafer to be solutions at different times, affecting the accuracy of the measurement results.

In view of this, the embodiment of the present invention hopes to provide a device for collecting metal ions on the surface of a silicon wafer; it is capable of improving the measurement accuracy of the metal ion content on the surface of the silicon wafer.

The technical solution of the embodiment of the present invention is implemented as follows: The embodiment of the present invention provides a collection device for metal ions on the surface of a silicon wafer, the collection device comprising: a collection module, the collection module can absorb 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; a solution chamber connected to the collection module, The solution chamber can store the scanning liquid for collecting metal ions on the surface of the silicon wafer 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 is arranged in the direction in which the scanning liquid is absorbed and located downstream of the solution chamber, and the switch module is used to control the collection module to absorb or spray the scanning liquid.

The embodiment of the present invention provides a collection device for metal ions on the surface of a silicon wafer; the collection device uses a collection module to absorb scanning liquid to collect metal ions on the surface of the silicon wafer, and at the same time, absorbs the same volume of scanning liquid through the collection module to measure the standard content of metal ions in the scanning liquid, that is, the scanning liquid in the same state is used to measure the content of metal ions to be measured on the surface of the silicon wafer and the standard content of metal ions in the scanning liquid, and the measurement result has high accuracy and small error.

1: Collector

11: Injection pump

12: Vacuum tube

13: External nozzle

14: Internal nozzle

15: Sealing plug

16: Valve

17: Vacuum pump

18:Edge support

W: Silicon wafer

2: Collection device

10: Collection module

101: First collection tube

102: Second collection tube

20: Solution chamber

201: scale line

30: Switch module

30-A: Switch module

30-B: Switch module

40: Nozzle

50: Power unit

Dro: Scanning fluid

Figure 1 is a schematic diagram of the structure of a collector scanning the surface and edge of a silicon wafer in a related technical solution; Figure 2 is a schematic diagram of the structure of a device for collecting metal ions on the surface of a silicon wafer provided in an embodiment of the present invention; Figure 3 is a schematic diagram of the structure of another device for collecting metal ions on the surface of a silicon wafer provided in an embodiment of the present invention.

In order to help the review committee understand the technical features, content and advantages of the present invention and the effects it can achieve, the present invention is described in detail as follows with accompanying drawings and appendices in the form of embodiments. The drawings used therein are only for illustration and auxiliary description purposes, and may not be the true proportions and precise configurations after the implementation of the present invention. Therefore, the proportions and configurations of the attached drawings should not be interpreted to limit the scope of application of the present invention in actual implementation.

In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the attached drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

In order to test the ultra-trace metal ion content in related technologies, the metal ion content test of silicon wafers requires the use of two devices, Vapor Phase Decomposition (VPD) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), to perform ion quantitative analysis on the collected VPD liquid. The general steps include: S1: Transfer the silicon wafer to the VPD etching tank through a robot, and at the same time, introduce HF solution vapor 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 layer of silicon dioxide film will appear on the surface of the silicon wafer and the surface of the silicon wafer after heating, and hydrofluoric acid vapor is used as Cleaning agent, a silicon dioxide film with a thickness of about 10 angstroms can be dissolved by 38% high-purity hydrofluoric acid within 5 minutes. At the same time, after the silicon wafer is cleaned with hydrofluoric acid, the outermost Si layer on the surface of the silicon wafer is almost H-bonded as the terminal structure, 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 and residues on the surface of the silicon wafer, thereby ensuring the integrity of VPD droplet collection; S2: On the scanning platform of the ICP-MS equipment, 1 ml is absorbed through the nozzle of the surface metal collection system The VPD droplets roll on the surface or edge of the silicon wafer to collect the metal components on the surface of the silicon wafer; S3: The VPD droplets containing metal components are atomized and then spectrally analyzed to test the metal content in the recovered liquid. The content of each metal in the recovered liquid is subtracted from the content of each metal in the VPD droplets to calculate the content of various metal ions on the surface of the silicon wafer.

Refer to Fig. 1, which shows a schematic diagram of a collector 1 in the related art scanning the surface and edge of a silicon wafer W. As shown in Fig. 1, the collector 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 robot places the back of the silicon wafer W with the oxide film removed on a carrier with air holes and adsorbs the back of the silicon wafer W on the carrier surface. The robot drives the bottom of the scanning outer nozzle 13 in the collector 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 the air in the cavity between the inner nozzle 14 and the outer nozzle 13 to provide a fixed vacuum. When the weight of the scanning liquid Dro is balanced with the vacuum degree in the cavity between the inner nozzle 14 and the outer nozzle 13, the vacuum pump 17 stops extracting air. At this time, part of the scanning liquid Dro drips into the cavity between the inner and outer nozzles, and the other part automatically suspends outside the cavity between the inner and outer nozzles to contact the surface of the silicon wafer W for scanning; finally, according to the set scanning route, the position of the scanning robot arm is adjusted to make the scanning liquid Dro drip on the surface and edge of the silicon wafer W and other different position areas and make the scanning liquid Dro roll on the surface and edge of the silicon wafer W to collect the metal components on the surface and edge of the silicon wafer W, as shown in A in Figure 1, the scanning liquid Dro scans the surface of the silicon wafer, and as shown in B in Figure 1, the scanning liquid Dro scans the edge of the silicon wafer.

However, in the process of collecting metal ions on the surface of the silicon wafer, it is necessary to first draw a certain volume of scanning liquid from the scanning liquid pool for measurement to obtain the standard content of metal ions in the scanning liquid, then draw the same volume of scanning liquid and roll it on the surface of the silicon wafer to collect the metal ions on the surface of the silicon wafer, and detect the content of metal ions to be measured in the collected scanning liquid, and obtain the metal ion content on the surface of the silicon wafer by subtracting it from the original content of the metal ions. However, in the specific implementation process, in order to prevent metal ions in the external environment from entering the scanning liquid pool and causing contamination to the scanning liquid, the scanning liquid in the scanning liquid pool is in a flowing state, resulting 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 surface of the silicon wafer being scanning liquids at different times, affecting the accuracy of the measurement results.

Based on the above description, referring to FIG. 2, the embodiment of the present invention provides a collection device 2 for metal ions on the surface of a silicon wafer, the collection device 2 comprising a collection module 10, the collection module 10 being capable of absorbing a set volume of scanning liquid Dro to collect metal ions on the surface of the silicon wafer and measuring the standard content of metal ions in the scanning liquid Dro; a solution chamber 20 connected to the collection module 10, the solution chamber 20 being capable of The scanning liquid Dro is stored to collect metal ions on the surface of the silicon wafer and measure the standard content of metal ions in the scanning liquid Dro, or to measure the standard content of metal ions in the scanning liquid Dro; a switch module 30 is arranged in the direction in which the scanning liquid Dro is absorbed and located downstream of the solution chamber 20, and the switch module 30 is used to control the collection module 10 to absorb or spray the scanning liquid Dro.

For the collection device 2 shown in FIG. 2 , the collection module 10 is used to absorb the scanning liquid Dro to collect the metal ions on the surface of the silicon wafer. At the same time, the same volume of scanning liquid is absorbed by the collection module 10 to measure the standard content of metal ions in the scanning liquid. That is, the scanning liquid in the same state is used to measure the content of metal ions to be measured on the surface of the silicon wafer and the standard content of metal ions in the scanning liquid. The measurement results are highly accurate and have small errors.

For the collection device 2 shown in FIG. 2 , in some possible implementations, as shown in FIG. 2 , a nozzle 40 is provided at one end of the collection module 10, and the nozzle 40 is configured to be able to quantitatively absorb or spray the scanning liquid Dro.

For the collection device 2 shown in FIG. 2 , in some possible implementations, the side wall of the solution chamber 20 is provided with a scale line 201 to control the volume of the scanning liquid Dro.

18MΩ．cm，水質：電阻率>18.2MΩ.cm，TOC<5ppb。 For the collection device 2 shown in FIG. 2 , in some possible implementations, the composition of the scanning liquid Dro is: HF with a mass fraction of 0.264% to 3%, H ₂ O ₂ with a mass fraction of 4% to 11.42%, and the rest is H ₂ O. Among them, the mass concentration of hydrogen peroxide (H ₂ O ₂ ) 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; ultrapure water: resistivity

18MΩ．cm, water quality: resistivity>18.2MΩ.cm, TOC<5ppb.

For the collection device 2 shown in FIG. 2, in some possible implementations, the collection device 2 also includes a power unit 50 connected to the other end of the collection module 10, and the power unit 50 is used to provide power for the collection module 10 to absorb the scanning liquid Dro.

It can be understood that, as shown in FIG2 , when the switch module 30 is turned on, the power unit 50 applies power, so that the first collection tube 101 absorbs a set volume of scanning liquid Dro, for example, 2 ml, from the scanning liquid pool, and places the 2 ml scanning liquid in the solution chamber 20; at the same time, the control switch module 30 drips 1 ml of scanning liquid Dro in the solution chamber 20 into the set container along the first collection tube 101 to measure the standard content of metal ions in the scanning liquid; then, the control switch module 30 gathers the remaining 1 ml of scanning liquid in the solution chamber 20 along the first collection tube 101 at the nozzle 40 to collect and measure the metal ions on the surface of the silicon wafer.

Based on this, for the collection device 2 shown in FIG. 2, in some examples, as shown in FIG. 2, the collection module 10 only includes a first collection tube 101, and the first collection tube 101 can absorb 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; and the scanning liquid Dro stored in the solution chamber 20 is used to collect metal ions on the surface of the silicon wafer and measure the standard content of metal ions in the scanning liquid Dro.

In addition, for the collection device 2 shown in FIG. 2, in some examples, as shown in FIG. 3, the collection module 10 includes a first collection tube 101 and a second collection tube 102; wherein the scanning liquid Dro absorbed by the first collection 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 collection tube 102 is used to collect metal ions on the surface of the silicon wafer; and the solution chamber 20 is only provided on the first collection tube 101; and the first collection tube 101 and the second collection tube 102 are both provided with a switch module 30.

For the above example, in a specific implementation process, the length of the second collection tube 102 is greater than the length of the first collection tube 101.

Specifically, the collection device 2 includes a first collection tube 101 and a second collection tube 102, and the first collection tube 101 and the second collection tube 102 are both connected to the power unit 50, and the first collection tube 101 is provided with a solution chamber 20; in addition, the first collection tube 101 and the second collection tube 102 are respectively provided with a corresponding switch module 30-A and a switch module 30-B; in the specific implementation process, the switch module 30 is controlled -A and switch module 30-B enable the first collection tube 101 and the second collection tube 102 to simultaneously absorb a set volume of scanning liquid Dro from the scanning liquid pool, for example, 1 ml of scanning liquid Dro; the scanning liquid Dro in the second collection tube 102 is gathered at the nozzle 40 to collect the metal ions on the surface of the silicon wafer, and the scanning liquid Dro in the first collection tube 101 is sucked in and contained in the built-in solution chamber 20. After the scanning liquid Dro in the second collection tube 102 is used to collect the metal ions on the surface of the silicon wafer, the scanning liquid Dro in the first collection tube 101 contained in the solution chamber 20 is used to measure the standard content of metal ions, so that the metal ion content on the surface of the silicon wafer is obtained by calculating the difference between the two measurement results.

It can be understood that the length of the second collection tube 102 is greater than the length of the first collection tube 101 so as to avoid the first collection tube 101 interfering with the second collection tube 102 when collecting metal ions on the surface of the silicon wafer.

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

The above is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. If the present invention is modified or replaced by something equivalent without departing from the spirit and scope of the present invention, it shall be covered by the protection scope of the patent application of the present invention.

2: Collection device

10: Collection module

20: Solution chamber

30: Switch module

40: Nozzle

50: Power unit

201: scale line

Dro: Scanning fluid

Claims (8)

A device for collecting metal ions on the surface of a silicon wafer, comprising: a collection module, which can absorb 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; a solution chamber connected to the collection module, which can store the scanning liquid for collecting metal ions on the surface of the silicon wafer 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 arranged in the direction in which the scanning liquid is absorbed and located downstream of the solution chamber, the switch module is used to control the collection module to absorb or spray the scanning liquid. As described in claim 1, a device for collecting metal ions on the surface of a silicon wafer is provided, wherein a nozzle is provided at one end of the collection module, and the nozzle is configured to be able to quantitatively absorb or spray the scanning liquid. As described in claim 1, the device for collecting metal ions on the surface of a silicon wafer, wherein the side wall of the solution chamber is provided with scale lines to control the volume of the scanning liquid. The device for collecting metal ions on the surface of a silicon wafer as described in claim 1, wherein the composition of the scanning liquid is: HF with a mass fraction of 0.264% to 3%, _H2O2 with a mass fraction of 4% to 11.42 _% , and the rest is _H2O . As described in claim 1, the collection device for metal ions on the surface of a silicon wafer further comprises a power unit connected to the other end of the collection module, and the power unit is used to provide power for the collection module to absorb the scanning liquid. A device for collecting metal ions on the surface of a silicon wafer as described in any one of claims 1 to 5, wherein the collection module only includes a first collection tube, the first collection tube is capable of sucking 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; and the scanning liquid stored in the solution chamber is used to collect metal ions on the surface of the silicon wafer and measure the standard content of metal ions in the scanning liquid. A device for collecting metal ions on the surface of a silicon wafer as described in any one of claims 1 to 5, wherein the collection module comprises a first collection tube and a second collection tube; wherein the scanning liquid sucked by the first collection tube is used to measure the standard content of metal ions in the scanning liquid, and the scanning liquid sucked by the second collection tube is used to collect metal ions on the surface of the silicon wafer; and the solution chamber is only provided on the first collection tube; and the first collection tube and the second collection tube are both provided with a switch module. A device for collecting metal ions on the surface of a silicon wafer as described in claim 7, wherein the length of the second collecting tube is greater than the length of the first collecting tube.

Images