KR101762350B1

KR101762350B1 - A cleaning device using the micro bubbles for silicone wafer and cleaning method using the same

Info

Publication number: KR101762350B1
Application number: KR1020150143319A
Authority: KR
Inventors: 장보윤; 김준수; 최선호; 송희은
Original assignee: 한국에너지기술연구원
Priority date: 2015-10-14
Filing date: 2015-10-14
Publication date: 2017-07-28
Also published as: KR20170044234A

Abstract

A cleaning device capable of improving the cleaning efficiency and a cleaning method using the same.
A silicon wafer cleaning apparatus using micro bubbles according to the present invention includes: a beam having a plurality of wafers; A nozzle unit located below the wafer and including a plurality of nozzles for uniformly distributing bubbles and cleaning liquid to the nozzles; A pump for transferring the bubble and the cleaning liquid to the nozzle unit; And a liquid circulation line for connecting the pump and the nozzle unit, temporarily storing the bubbles and the cleaning liquid, and circulating the liquid, wherein the nozzle includes a first nozzle and a second nozzle, And the bubbles are injected from the nozzles and penetrate into a gap between one wafer and another wafer to separate a plurality of wafers, and the cleaning liquid is sprayed from the nozzles and is separated from one wafer And penetrates into a gap between one wafer to remove remaining fine particles and contaminants on the wafer surface.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a silicon wafer cleaning apparatus using micro bubbles and a cleaning method using the micro bubbles.

The present invention relates to a silicon wafer cleaning apparatus and a cleaning method using the cleaning apparatus. More particularly, the present invention relates to a cleaning apparatus capable of suppressing breakage of a wafer and improving cleaning efficiency, and a cleaning method using the cleaning apparatus.

Referring to FIG. 1, in the case of a silicon wafer generally used for a solar cell and a semiconductor, a silicon ingot is rubbed against a wire saw to perform a cutting process, and a wafer is manufactured through a demounting, separation, and washing process.

Reducing the thickness of the wafer increases the number of wafers produced per ingot, so productivity increases in inverse proportion to thickness. In the case of a 180 μm wafer having a commercialized thickness, the wafer is relatively smoothly separated after the demounting process. However, when the thickness of the wafer is reduced to 150 μm or less, the gap between the wafers 40 increases as shown in Figs. 2 and 3, and the slurry 30, the cleaning liquid, the fine particles, Occurs. In addition, the phenomenon that the suspension can not be discharged to the outside occurs due to the capillary phenomenon. If such wafers are separated by a mechanical load in the separation process, the fracture rate increases sharply. When the thickness of the wafer is 150 mu m or less, the wafer is cut and a high-viscosity liquid phase in which slurry, silicon and wire fine particles other than cutting oil are mixed together with impurities such as silicon dust and silicon particles, .

Accordingly, there is a demand for an apparatus for removing contaminants remaining on the surface of the wafer and for facilitating the separation of the wafer.

A related art related to the present invention is Korean Patent Laid-Open Publication No. 2001-0018028 (published on Mar. 3, 2001), which discloses a wafer cleaning apparatus having a spray nozzle on a cover.

SUMMARY OF THE INVENTION An object of the present invention is to provide a silicon wafer cleaning apparatus capable of preventing damage to wafers and improving cleaning efficiency in a wafer separation and cleaning step.

It is another object of the present invention to provide a method of cleaning a silicon wafer using the cleaning apparatus.

According to an aspect of the present invention, there is provided a silicon wafer cleaning apparatus using micro bubbles, comprising: a beam having a plurality of wafers; A nozzle unit located below the wafer and including a plurality of nozzles for uniformly distributing bubbles and cleaning liquid to the nozzles; A pump for transferring the bubble and the cleaning liquid to the nozzle unit; And a liquid circulation line for connecting the pump and the nozzle unit, temporarily storing the bubbles and the cleaning liquid, and circulating the liquid, wherein the nozzle includes a first nozzle and a second nozzle, Wherein the bubble is injected from the first nozzle to penetrate into a gap between one wafer and another wafer to separate a plurality of wafers, and the cleaning liquid separates the wafers from the first nozzle and the second nozzle, And penetrates into a gap between one wafer and another wafer to remove remaining fine particles and contaminants on the wafer surface.

The first nozzle may be a diffusion type nozzle, and the second nozzle may be a slit type nozzle.

The hole diameter of the diffusion type nozzle may be 5 to 50 탆.

The diameter of the bubbles may be 5 탆 or more.

The width of the slit-shaped nozzle may be 0.05 to 10 mm.

When the nozzle including the slit-shaped nozzle is positioned on the front or rear surface of the wafer positioned at the edge, the inclined angle between the wafer positioned at the edge and the slit-shaped nozzle may be 12 degrees or less.

According to another aspect of the present invention, there is provided a method of cleaning a silicon wafer using microbubbles, comprising: (a) supplying a bubble and a cleaning liquid temporarily stored in a liquid phase circulation line to a nozzle unit including a plurality of first and second nozzles, ; (b) supplying the bubble and cleaning liquid ejected from the plurality of first nozzles to the surface of the wafer and performing a primary cleaning; And (c) supplying the cleaning liquid and the drying air sprayed from the plurality of second nozzles to the surface of the first cleaned wafer to perform second cleaning and drying of the wafer, wherein the first nozzle and the Two nozzles are positioned below the gap between one wafer and the other wafer and the bubbles are injected from the first nozzle to penetrate into a gap between one wafer and another wafer to separate a plurality of wafers, Is injected from the first nozzle and the second nozzle to penetrate into a gap between one wafer and the other wafer to remove remaining fine particles and contaminants on the wafer surface.

The diameter of the bubbles may be 5 탆 or more.

Wherein when the nozzle portion including the plurality of second nozzles is positioned on the front surface or the rear surface of the wafer positioned at the edge, the angle of inclination between the wafer positioned at the edge and the second nozzle is 12 degrees or less, 2 nozzle, and the wafer may be secondly cleaned and then dried.

The silicon wafer cleaning apparatus according to the present invention can increase the diameter of the bubbles due to the contact between the bubbles and improve the separation of the wafers by spraying the microbubbles on the surface of the wafer from a plurality of nozzles.

In addition, since the slit-shaped nozzle is positioned on the lower side or the side of the wafer, the cleaning liquid is sprayed onto the wafer surface, thereby preventing breakage of the wafer and removing residual contaminants.

Further, by simultaneously blowing the bubble and the cleaning liquid on the surface of the silicon wafer by using the cleaning apparatus of the present invention, the breakage rate of the wafer is reduced to 15% to 50% as compared with the cleaning process using the conventional cleaning apparatus having one nozzle There is an effect that can be.

1 is a flowchart showing a conventional method for manufacturing a silicon wafer.
2 is a cross-sectional view showing the state of a silicon wafer after a conventional mounting process.
3 is a photograph showing a bonding state of a silicon wafer after a conventional mounting process.
4 is a cross-sectional view showing a conventional cleaning apparatus for a silicon wafer.
5 is a photograph showing a conventional separation and cleaning process of a silicon wafer.
6 is a photograph of a damaged portion of a conventional silicon wafer.
FIG. 7 is a photograph showing contaminants remaining on a conventional silicon wafer.
FIG. 8 is a photograph of a conventional cleaning apparatus for a silicon wafer having nozzles and a wafer thus damaged.
9 is a cross-sectional view of a silicon wafer cleaning apparatus according to an embodiment of the present invention.
10 is a perspective view of a nozzle unit including a plurality of nozzles according to an embodiment of the present invention.
11 is a perspective view of a nozzle unit including a plurality of nozzles according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a silicon wafer cleaning apparatus using a bubble according to a preferred embodiment of the present invention and a cleaning method using the same will be described in detail with reference to the accompanying drawings.

1 is a flowchart showing a conventional method for manufacturing a silicon wafer.

Referring to FIGS. 1 to 3, after a ingot is cut using a wire saw, a wafer is produced through a demounting step, a wafer separation step, a wafer cleaning and drying step. The state of the wafer after the demounting step is that there is a suspension 30 containing slurry, washing liquid and fine particles between gaps between the wafers 40, and the suspension can not be discharged to the outside due to capillary phenomenon.

Conventionally, as shown in FIG. 5, by spraying the bubble and the cleaning liquid from one nozzle, breakage occurs in the wafer close to the nozzle, and contaminants can not be removed from the wafer at a relatively long distance and remain.

In order to solve such problems, the present invention provides a silicon wafer cleaning apparatus and cleaning method using the same, which can improve separation and cleaning effects of wafers by providing a plurality of nozzles.

9 is a cross-sectional view of a silicon wafer cleaning apparatus according to an embodiment of the present invention.

Referring to FIG. 9, a silicon wafer cleaning apparatus includes a wafer having a plurality of wafers attached thereto; A nozzle unit; Pump; And a liquid phase circulation line.

A plurality of wafers are attached to one side of the beam, and an adhesive layer (not shown) may be provided between the beam and the wafer.

The nozzle portion 72 is located below the wafer and includes a plurality of nozzles.

The nozzle unit 72 serves as a dispenser for preventing the concentration of the bubbles and the cleaning liquid on the plurality of nozzles, and may be used to uniformly distribute the bubbles and the cleaning liquid to the plurality of nozzles.

The nozzles are positioned at a predetermined interval under one gap between the wafers and the other wafers so that the bubbles and the cleaning liquid can be sprayed between the gaps between the wafers, that is, between the wafers. When the nozzle unit includes a plurality of nozzles without a predetermined interval, the wafer may be damaged when the cleaning liquid is sprayed.

Conventionally, in the case of a cleaning apparatus including a single nozzle, the cleaning efficiency of the wafer is lowered and the wafer is damaged. The cleaning apparatus of the present invention includes a plurality of nozzles other than one nozzle, so that the bubble and the cleaning liquid are uniformly sprayed on the wafer surface, thereby further improving the separation and cleaning effect of the wafer.

The supply line 1 (53a) and the supply line 2 (53b) may be provided on both sides of the nozzle unit 72, and may be provided only on one side. The supply lines 1 and 2 may be connected to a liquid circulation line to be described later.

The nozzle may include a first nozzle and a second nozzle, the first nozzle may be a diffusion type nozzle, and the second nozzle may be a slit type nozzle.

Referring to FIGS. 9 and 10, a plurality of diffusion type nozzles 72a are included in the nozzle portion 72. FIG. The diameter of the hole 73 of the diffusion type nozzle is preferably 5 to 50 mu m. When the diameter of the hole is less than 5 mu m, the micro bubble to be described later can not be injected from the hole of the nozzle, so that the cleaning efficiency can be reduced. Conversely, when the diameter of the hole exceeds 50 mu m, the flow rate of the cleaning liquid supplied from the nozzle increases, and the cleaning efficiency of the wafer may be reduced.

Referring to FIG. 11, a plurality of slit-shaped nozzles 72b are included in the nozzle portion.

In the slit-shaped nozzle 72b, the cleaning liquid and the drying air can be sprayed.

The width of the slit-shaped nozzle 72b is preferably 0.05 to 10 mm.

When the width of the slit-shaped nozzle 72b is less than 0.05 mm, turbulence in which the cleaning liquid and the dry wind are irregularly jetted may be generated, and not only the vibration of the wafer may occur, but the wafer may be damaged due to pressure.

Conversely, when the width of the slit-shaped nozzle 72b exceeds 10 mm, the cleaning efficiency of the wafer surface can be reduced.

The nozzle portion including the plurality of slit-shaped nozzles 72b may be located below the wafer, or may be located on the front or rear surface of the wafer, as described above. When the nozzle including the slit-shaped nozzle is positioned on the front or rear surface of the wafer positioned at the edge, the inclined angle between the wafer positioned at the edge and the slit-shaped nozzle may be 12 degrees or less. The subtended angle refers to the angle between the wafer and the nozzle surface located at the edge. When the angle exceeds 12 degrees, the cleaning effect of the wafer may be insufficient because the distance between the wafer located at the edge and the nozzle is far.

The bubbles are injected from the nozzles and penetrate into the gap between one wafer and the other wafer, so that the bubbles are repeatedly merged due to the contact between the bubbles, and the diameter of the bubbles is increased to physically separate the plurality of wafers . Further, by removing the fine particles remaining on the wafer surface or between the wafers and discharging the fine particles to the outside, it is possible to reduce the defects of the silicon wafer and to prevent contamination of the wafer surface.

The diameter of the bubbles is preferably 5 mu m or more. In consideration of the hole diameter of the nozzle, the diameter of the bubble is more preferably 5 to 40 mu m.

When the diameter of the bubble is less than 5 mu m, the cleaning effect of the wafer may be insufficient even if the diameter due to the contact between the bubbles increases at the time of jetting from the nozzle because the size of the bubble is too small. Also, the bubbles can move to the top of the cleaning apparatus rather than the bubbles penetrating between the wafers.

The cleaning liquid is sprayed from the nozzle to penetrate into the gap between one wafer and the other wafer to remove the remaining fine particles and contaminants on the wafer surface.

The flow rate of the washing liquid can be adjusted depending on the size of the washing apparatus, the number of wafers, and the like. For example, the cleaning liquid may be supplied to the wafer surface at an average speed of 1 L / min or less, and may be supplied to the wafer surface at an average speed of 50 L / min or less, but is not limited thereto.

The cleaning liquid may include at least one of ethylene glycol-based cutting oil and surfactant, but is not limited thereto.

The cutting oil is a metal working oil used in metal processing such as cutting, grinding and polishing, and has the effect of cleaning the surface of the machining area precisely and cleanly. Examples of the ethylene glycol system include polyethylene glycol, ethylene glycol monomethyl ether, and ethylene glycol diphenyl ether.

Surfactants include cationic, anionic, amphoteric and nonionic surfactants classified according to ionicity, and it is preferable to use at least one of the above four surfactants in order to improve the washing action and the disinfecting action. It is also preferable to use LES including sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate (ALS), and ammonium laureth sulfate (ALES) among the surfactants having a detergent function .

In addition to the above cutting oil and surfactant, washing water containing deionized water may be further used to improve the cleaning effect.

The pump 60 may be provided on one side of the beam to transfer bubbles and cleaning liquid to the nozzle unit 72, and may be provided on both sides of the beam. The pump 60 can transfer the liquid or gas to the nozzle unit through the liquid circulation line 50 by the pressure action.

The liquid circulation line 50 connects the pump 60 and the nozzle unit 72, and temporarily stores and circulates the bubble and the cleaning liquid. For example, bubbles and washing liquid transferred from the liquid circulation line 50 may be supplied to the nozzle portion and then sprayed from a plurality of nozzles. The sprayed bubbles and the cleaning liquid are supplied to the surface of the wafer and then dropped to the nozzle unit 72. The bubbles and the cleaning liquid are circulated in the liquid circulation line 50 by the action of the pump and can be transferred again to the nozzle unit for reuse.

The liquid circulation line 50 may further include a bubble generator 71. The bubble generator 71 may be positioned at a rear end of the pump in a direction in which the bubble and the washing liquid are transferred. The bubble generator 71 continuously supplies additional bubbles in addition to bubbles circulated in the liquid phase circulation line 50.

The bubble supply line 52 shown in Fig. 9 indicates a space in which bubbles are supplied to the wafers in the cleaning apparatus.

A method of cleaning a silicon wafer according to the present invention comprises the steps of: (a) transferring a bubble and a cleaning liquid temporarily stored in a liquid circulation line by a pump to a nozzle section including a plurality of first nozzles and a second nozzle; (b) supplying the bubble and cleaning liquid ejected from the plurality of first nozzles to the surface of the wafer and performing a primary cleaning; And (c) supplying the cleaning liquid and the drying air sprayed from the plurality of second nozzles to the surface of the first cleaned wafer to secondly clean the wafer, and then drying the wafer.

More specifically, the pump transfers bubbles and cleaning liquid temporarily stored in the liquid phase circulation line to a nozzle section including a plurality of first nozzles and a second nozzle.

The bubbles and cleaning liquid transferred to the nozzle section can be sprayed to the wafer surface through the nozzles.

A plurality of wafers produced by sowing a silicon ingot are cleaned, and a bubble and a cleaning liquid are supplied to the surface of the wafer to be firstly cleaned. In the first cleaning step, a cleaning liquid may be sprayed from a bubble and a cleaning liquid sprayed from a diffusion type nozzle located below the wafer, or a cleaning liquid sprayed from a slit type nozzle. However, a diffusion nozzle is used to further improve the separation and cleaning efficiency of the wafer . At this time, since the bubbles are continuously supplied to the wafer surface, the wafer can be easily separated and the cleaning efficiency can be improved.

As shown in FIG. 9, the diffusion type nozzle or the slit type nozzle may be positioned under the gap between one wafer and the other wafer.

After the first wash, a second wash step is performed.

In the second cleaning step, cleaning can be performed using a plurality of slit-shaped nozzles located at the bottom, front, or backside of the wafer. More specifically, the cleaning liquid and the drying air are sprayed from the slit-shaped nozzle, the wafer is secondly washed, and then dried.

At this time, when a nozzle portion including a plurality of slit-shaped nozzles is positioned on the front surface or the rear surface of the wafer, the angle between the wafer positioned at the edge and the nozzle may be 12 degrees or less.

Also, the flow rate of the cleaning liquid and the drying air blown from the slit-type nozzle can be determined in a fluid manner so as not to cause vibration and warping of the wafer, and the flow rate can be controlled according to the size of the cleaning device, the number of wafers,

The bubbles and the washing liquid may be as described above.

As described above, by using the nozzle capable of jetting the microbubbles, the infiltration of the microbubbles on the wafer surface can be smoothly performed, the cleaning efficiency using the bubbles can be further improved, the wafer can be physically separated, Can be minimized.

Particularly, even when a crystalline silicon wafer having a thickness of 150 탆 or less is washed, there is an advantage that the damage to the wafer can be minimized and the wafer can be cleaned.

In addition, cleaning efficiency can be improved by simultaneously spraying the bubble and the cleaning liquid on the wafer surface with the plurality of nozzles.

In addition, when the wafer is cleaned using the cleaning apparatus of the present invention, the breakage rate of the wafer is relatively reduced by 15% to 50% as compared with the conventional cleaning apparatus having one nozzle.

The silicon wafer cleaning apparatus using micro bubbles and the cleaning method using the same will be described in detail as follows.

1. Silicon wafer cleaning

Example

As shown in FIG. 9, the microbubbles and the cleaning liquid having a diameter of 5 mu m were jetted from the first nozzle by using the cleaning apparatus of the present invention, and then the silicon wafer was firstly cleaned, and then the cleaning liquid and the drying air were jetted from the second nozzle The silicon wafer was washed second and then dried. The hole diameter of the first nozzle was 10 mu m, and the width of the second nozzle was 10 mm. The position of the second nozzle is located at the bottom and front of the wafer, and when positioned at the front, the angle between the wafer and the second nozzle located at the edge is 12 degrees.

Comparative Example

As shown in FIG. 9, the microbubbles and the cleaning liquid having a diameter of 2 mu m were jetted from the first nozzle by using the cleaning apparatus of the present invention, and then the silicon wafer was firstly cleaned, and then the cleaning liquid and the drying air were jetted from the second nozzle The silicon wafer was washed second and then dried. The hole diameter of the first nozzle was 10 mu m, and the width of the second nozzle was 0.03 mm. The position of the second nozzle is located at the bottom and front of the wafer, and when it is positioned at the front, the angle between the wafer and the second nozzle at the edge is 20 degrees.

2. Results

The degree of breakage of the cleaned silicon wafer was visually observed in Examples and Comparative Examples, and the results are shown in Table 1.

(1) Degree of wafer damage

50% when the breakage portion of the wafer is half or more, and 10% when there is almost no breakage portion of the wafer.

(2) Wafer cleaning degree

If the surface of the wafer is clean without any contaminants, it is marked as "good", and if there is more than 40% of contaminants such as suspensions, it is marked as "poor".

[Table 1]

The silicon wafer according to the embodiment had a bubble diameter of 5 占 퐉 and a width of the second nozzle of 10 mm, so that the degree of wafer breakage after cleaning was as low as 10%. On the contrary, in the case of the comparative example, since the diameter of the bubble was too small to increase the diameter due to the contact between the bubbles, the washing process was not properly performed. In addition, since the width of the second nozzle was 0.03 mm, turbulence was formed and the wafer was damaged during the washing liquid and dry air blowing.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

10: Beam
20: Adhesive
30: Suspension
40: wafer
50: Liquid circulation line
51: gas supply line
52: Bubble supply line
53a: supply line 1
53b: supply line 2
60: Pump
70: 1 nozzle
71: bubble generator
72:
72a: diffusion nozzle
72b: slit nozzle
73: hole of diffusion type nozzle

Claims

A silicon wafer cleaning apparatus for cleaning a plurality of wafers produced by sawing a silicon ingot,
A beam having a plurality of wafers attached thereto;
A nozzle unit located below the wafer and including a plurality of nozzles for uniformly distributing bubbles and cleaning liquid to the nozzles;
A pump for transferring the bubble and the cleaning liquid to the nozzle unit; And
And a liquid circulation line connecting the pump and the nozzle unit to temporarily store and circulate the bubbles and the cleaning liquid,
Wherein the nozzle includes a first nozzle and a second nozzle,
The nozzle being located below a gap between one wafer and the other wafer,
The bubbles are injected from a first nozzle and penetrate into a gap between one wafer and another wafer to separate a plurality of wafers, and the cleaning liquid is ejected from the first nozzle and the second nozzle, And penetrates into the gaps between the wafers to remove remaining fine particles and contaminants on the wafer surface.

The method according to claim 1,
Wherein the first nozzle is a diffusion type nozzle, and the second nozzle is a slit type nozzle.

3. The method of claim 2,
And the hole diameter of the diffusion nozzle is 5 to 50 mu m.

The method according to claim 1,
Wherein the bubble has a diameter of 5 mu m or more.

3. The method of claim 2,
And the width of the slit-shaped nozzle is 0.05 to 10 mm.

3. The method of claim 2,
Wherein the inclined angle between the wafer positioned at the edge and the slit-shaped nozzle when the nozzle including the slit-shaped nozzle is positioned on the front or rear surface of the wafer positioned at the edge is 12 degrees or less.

(a) transferring bubbles and cleaning liquid temporarily stored in a liquid circulation line by a pump to a nozzle section including a plurality of first nozzles and a second nozzle;
(b) supplying the bubble and cleaning liquid ejected from the plurality of first nozzles to the surface of the wafer and performing a primary cleaning; And
(c) supplying the cleaning liquid and the drying air sprayed from the plurality of second nozzles to the surface of the first cleaned wafer to secondly clean the wafer, and then drying the wafer,
The first nozzle and the second nozzle being located under a gap between one wafer and the other wafer,
The bubbles are injected from a first nozzle and penetrate into a gap between one wafer and another wafer to separate a plurality of wafers, and the cleaning liquid is ejected from the first nozzle and the second nozzle, And penetrating into a gap between the wafers to remove remaining fine particles and contaminants on the wafer surface.

8. The method of claim 7,
Wherein the first nozzle is a diffusion type nozzle, and the second nozzle is a slit type nozzle.

8. The method of claim 7,
Wherein the diameter of the bubble is 5 占 퐉 or more.

8. The method of claim 7,
Wherein when the nozzle portion including the plurality of second nozzles is positioned on the front surface or the rear surface of the wafer positioned at the edge, the angle of inclination between the wafer positioned at the edge and the second nozzle is 12 degrees or less, 2 nozzle, and drying the wafer after the wafer is secondly cleaned by supplying the cleaning liquid and the drying air.