JP2006066793A - Wafer cleaning method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently clean without causing omissions or damages of wafers even if an opening gap between the wafers is very narrow. <P>SOLUTION: A block-like wafer W' to which a plate-like retaining tool is adhered is retained in an air, and a cleaning solution is sprayed from the side of this block-like wafer W' to an opening gas G between wafers W, whereby the flow rate of the cleaning solution can be increased with a smaller resistance than in a liquid, and the cleaning solution is smoothly flown into the opening gas G between the wafers W in a blocked state, and is also flown into between the wafers W adhered partially. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

In the present invention, for example, in the process of manufacturing a silicon semiconductor substrate, a rod-shaped ingot is cut with a wire saw or the like and separated into a thin plate-like wafer, and then a slurry containing chips or abrasive grains remaining between these wafers is used. The present invention relates to a wafer cleaning method for cleaning dirt and a cleaning apparatus used therefor.
Specifically, one side of a bar-shaped ingot made of a semiconductor material is bonded to a plate-shaped holder and cut and separated into a plurality of wafers, and the gap between the cut and separated wafers is bonded to the plate-shaped holder. Relates to a wafer cleaning method and a cleaning apparatus.

  Conventionally, as this type of wafer cleaning method, a plurality of wafers cut and separated with a wire saw or the like are bonded to a plate-shaped jig (plate-shaped support member), and the plate-shaped jig is used as a cleaning jig. Attach them, immerse them in the first washing tank (first tank), bubbling with air and wash off with oil using a shower, then dip in the second washing tank (second tank) Ultrasonic cleaning with oil washing, followed by soaking in the 3rd cleaning tank (3rd tank) and 4th cleaning tank (4th tank) sequentially, ultrasonic cleaning using alkaline detergent etc. Finally, the wafers are separated one by one by sequentially immersing them in a fifth cleaning tank (fifth tank) and a sixth cleaning tank (sixth tank) and ultrasonically cleaning with water. There is a cleaning basket that can be cleaned without being refilled (see, for example, Patent Document 1).

Japanese Patent No. 2902880 (page 1-2, FIG. 1-6)

However, in such a conventional wafer cleaning method and apparatus, the interval between the wafers cut by the wire saw is very narrow (300 μm), and the cut wafers are in close contact with each other in units of several tens of sheets. Even if it is immersed in multiple cleaning tanks and air bubbling, showering or ultrasonic cleaning is performed, the cleaning liquid does not surely enter between the partially adhered wafers, so the cleaning effect does not reach sufficiently, Since there was almost no replacement, there was a problem that it was difficult to remove dirt.
If air bubbling, showering, or ultrasonic cleaning is strengthened in order to remove dirt by this method, the wafer may fall off or be damaged.
On the other hand, in order to prevent damage, if the tact time is increased or the tact time is desired to be shortened, the cleaning tank needs to be multi-staged, and the plate-like holding is maintained over these multi-stage cleaning tanks. The block-shaped wafer adhered to the tool must be transferred in a short time, and there is a problem that the cleaning process is complicated, the structure of the entire cleaning apparatus is complicated, and the exclusive space is widened.
In particular, in recent years, in order to minimize crystal loss, the wire tends to be thin and the abrasive grain size tends to be small, so that the gap between wafers is becoming increasingly narrow (less than 0.2 mm). Is no longer suitable.

The inventions according to the first and second aspects of the present invention are intended to enable efficient cleaning without causing dropping or damage of the wafer even if the gap between the wafers is very narrow.
The invention described in claim 3 is intended to further improve the degree of cleaning in addition to the object of the invention described in claim 2.

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention holds a block-shaped wafer bonded to a plate-shaped holder in the air, and the wafer between the wafers from the side of the block-shaped wafer. The wafer cleaning method is characterized in that a cleaning liquid is ejected toward the gap.
According to a second aspect of the present invention, there is provided holding means for holding in the air a block-shaped wafer to which a plate-shaped holder is bonded, and a cleaning liquid jet is directed to the gap between the wafers on the side of the block-shaped wafer. It is the wafer cleaning device arranged.
According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, the nozzle is a nozzle for injecting cleaning water, and the nozzle is free from the wafer bonding side along the side surface of the block-shaped wafer. It is characterized by adding a structure moved toward the end.

According to the first aspect of the present invention, the block-shaped wafer to which the plate-shaped holder is bonded is held in the air, and the cleaning liquid is ejected from the side of the block-shaped wafer toward the gap between the wafers. As a result, the resistance of the cleaning liquid is less than that in the liquid, and the flow rate of the cleaning liquid can be increased. Even in the block state, the cleaning liquid smoothly flows into the gaps between the wafers and also flows between partially adhered wafers.
Therefore, even if the gap between the wafers is very narrow, the wafer can be efficiently cleaned without causing the wafer to drop off or be damaged.
As a result, the number of tanks can be minimized compared to the conventional method of air bubbling, showering and ultrasonic cleaning by immersing in multiple cleaning tanks, cleaning time, equipment investment, space, chemical usage, water usage Can be reduced.
Furthermore, it is not necessary to use a chemical solution depending on the required quality of the cleanliness, which contributes to cost reduction and environmental load reduction.

According to the second aspect of the present invention, the block-shaped wafer to which the plate-shaped holder is bonded is held in the air by the holding means, and is directed from the jet port disposed on the side of the block-shaped wafer toward the gap between the wafers. By jetting the cleaning liquid, it is possible to increase the flow rate of the cleaning liquid with less resistance compared to the liquid, and the cleaning liquid smoothly flows into the gap between the wafers even in the block state, and flows into the partially adhered wafers. .
Therefore, even if the gap between the wafers is very narrow, the wafer can be efficiently cleaned without causing the wafer to drop off or be damaged.
As a result, the number of tanks is minimal compared to conventional equipment that immerses in multiple cleaning tanks and performs air bubbling, showering, and ultrasonic cleaning, cleaning time, capital investment, space, chemical usage, and water usage. Can be reduced.
Furthermore, it is not necessary to use a chemical solution depending on the required quality of the cleanliness, which contributes to cost reduction and environmental load reduction.

In addition to the effect of the invention of claim 2, the invention of claim 3 jets cleaning water while moving the nozzle as a jet outlet along the side surface of the block-shaped wafer from the wafer bonding side to the wafer free end, The cleaning liquid spreads uniformly over the entire space between the wafers.
Therefore, the degree of cleaning can be further improved.

  In the wafer cleaning method of the present invention, in a prior slicing step, a rod-shaped ingot (not shown) made of a semiconductor material such as silicon, for example, cuts a wire saw or the like while the plate-shaped holder H is adhered to one side surface thereof. A plurality of wafers W are cut and separated by a machine (not shown) at intervals of about 0.1 to 0.3 mm, and in the subsequent cleaning process, as shown in FIGS. The block-shaped wafer W ′ bonded to the wafer W is held in the air, and the cleaning liquid is ejected from the side of the block-shaped wafer W ′ toward the gap G between the wafers W, whereby the gap G between the wafers W is discharged. All of the above are cleaned while adhered to the plate-shaped holder H.

  In the illustrated example, a substantially circular shape is obtained with a cutting machine (not shown) such as a wire saw while the plate-like holder H is adhered to an orientation flat OF cut out on one side of a cylindrical ingot (not shown). A case where the wafer W is cut and separated is shown.

As shown in FIGS. 1 to 5 and FIG. 7, the cleaning apparatus used in the wafer cleaning method of the present invention holds a block-like wafer W ′ to which the plate-like holder H is bonded in the air. Means 1 are provided, and a cleaning liquid jet port 2 made of, for example, a nozzle or the like is disposed on the side of the block-shaped wafer W ′ toward the gap G between the wafers W.
Embodiments of the present invention will be described below with reference to the drawings.

  In the first embodiment, as shown in FIGS. 1A to 1C, a plate-like holder H to which a wafer W as an object to be cleaned is bonded is held in the air by a holding means 1, and this block-like wafer is used. One jet port 2 shorter than the wafer arrangement direction Y corresponding to the length direction of the ingot is provided so as to face one of the side surfaces Wa ′ of W ′, and the side surface Wa ′ and the jet port 2 of these block-shaped wafers W ′. Are moved in the wafer arrangement direction Y and the wafer axial direction X orthogonal to the wafer arrangement direction Y, respectively, and are ejected to all the gaps G between the wafers W. Residual swarf and slurry containing abrasive grains are cleaned.

  In the example shown in FIG. 1 (a), a plate-like holder H is suspended by a holding means 1 described later so that the block-shaped wafer W ′ protrudes downward, and the left and right sides of the suspended block-shaped wafer W ′ are left and right. The cleaning liquid is ejected from the ejection port 2 toward one of the side surfaces Wa ′, and at the same time, the ejection port 2 is reciprocated in the wafer axial direction X and the wafer arrangement direction Y.

  In the example shown in FIG. 1B, the holding means 1 holds the plate-shaped holder H so that the block-shaped wafer W ′ protrudes sideways, and the cleaning liquid is ejected from the ejection port 2 toward the upper side surface Wa ′. At the same time, the nozzle 2 is reciprocated in the wafer axial direction X and the wafer arrangement direction Y.

  In the example shown in FIG. 1 (c), the holding means 1 holds the plate-like holder H so that the block-shaped wafer W ′ protrudes upward, and the jet port 2 faces either the left or right side surface Wa ′. At the same time, the cleaning liquid is ejected from the nozzle 2, and the ejection port 2 is reciprocated in the wafer axial direction X and the wafer arrangement direction Y.

  As the holding means 1, in the illustrated example, a suction suction mechanism such as a suction pad as shown in FIG. 1A or a holding mechanism having a conventionally well-known structure such as a robot hand, for example, is used, and its tip is a plate. The block-shaped wafer W ′ is held without being immersed in the liquid by being brought into contact with the shaped holder H and detachably locked.

  Further, the holding means 1 and the block-shaped wafer W ′ are accommodated in a sealed chamber (not shown) surrounded by a partition wall in consideration of scattering of cleaning liquid ejected from a later-described ejection port 2. It is desirable to do.

  Further, if necessary, the holding means 1 moves the wafer in the wafer axial direction X and the wafer arrangement direction Y in order to uniformly apply the cleaning liquid from the jet nozzle 2 over the entire gap G between the wafers W. As shown in FIGS. 1A to 1C, the block-shaped wafer W ′ may be rotated by a predetermined angle (90 degrees in the illustrated example).

  As the above-mentioned jet nozzle 2, a nozzle made of a commercially available hose 2 a or a tapered cylindrical body (not shown) that is generally used as shown in the figure is used, and its base end is a supply source of a cleaning liquid (see FIG. (Not shown) and a moving mechanism (not shown) for linearly reciprocating the jet nozzle 2 in the wafer axial direction X and the wafer arranging direction Y, respectively, is connected to operate the controller (not shown). Based on the control, an appropriate flow rate of the cleaning liquid is jetted from the side surface Wa ′ of the block-shaped wafer W ′ toward the gap G between the wafers W while reciprocating the front end port 2b in the wafer axial direction X and the wafer arrangement direction Y. ing.

Further, if necessary, the ejection port 2 also reciprocates linearly in the wafer axial direction X and the wafer arrangement direction Y in order to uniformly apply the cleaning liquid ejected therefrom over the entire surface of the gap G between the wafers W. In addition, the wafer is moved by a predetermined angle, 90 degrees in the illustrated example, or 180 ° C. so as to face a plurality of upper, lower, left and right side surfaces Wa ′ of the block-shaped wafer W ′. You may reciprocate in the wafer arrangement direction Y.
When the block-shaped wafer W ′ as shown in the example has a substantially cylindrical shape, the arc-shaped outer surface Wa ′ and the arc-shaped outer surface Wa ′ are reciprocated in the arc direction along the arc-shaped outer surface Wa ′. You may make it the jet nozzle 2 move, maintaining equal intervals.

  Further, as the cleaning liquid, water (pure water), a chemical liquid such as an alkaline solution, a solvent or a surfactant, or a liquid such as ultrasonic water can be used. You may make it eject in order.

  When the both sides of the block-like wafer W ′ held by the holding means 1 are moved without moving the side surface Wa ′ without moving the side surface Wa ′, the two are relatively moved as shown in FIG. b) and as shown in FIG. 3, it is moved to the wafer free end W2 from the wafer bonding side W1 where it is bonded to the plate-shaped holder H and the gap G at the time of cutting exists reliably (not in close contact). Is preferably poured into the gap G between the wafers W.

  In the case of FIGS. 2A and 2B, the jet nozzle 2 is moved in the wafer axial direction X from the wafer bonding side W1, and after reaching the wafer free end W2 and returning in the reverse direction, the wafer arrangement direction Y After that, the cleaning liquid is sprayed over the entire side surface Wa ′ of the block-shaped wafer W ′ by repeating the above-described movement.

  In the case of FIG. 3, the cleaning liquid is moved over the entire side surface Wa ′ of the block-shaped wafer W ′ by reciprocating from the wafer bonding side W1 in the wafer arrangement direction Y and moving in a zigzag toward the wafer free end W2. It is made to be injected.

  Further, the positional relationship between the side surface Wa ′ of the block-shaped wafer W ′ and the ejection port 2 is as shown in FIG. 4 by bringing the ejection port 2 as close as possible to or in contact with the side surface Wa ′. It is preferable that the cleaning liquid is forcibly introduced into the gap G between the wafers W and cleaned without waste.

  Furthermore, the jet nozzle 2 has a cleaning liquid jetting force increased by reducing the width dimension of the tip opening 2b relative to the length dimension in the wafer arrangement direction Y, as shown in FIG. Even if the cut wafers W adhere to each other in units of several tens, the gap G between the wafers W can be expanded several times.

Next, operation effects of the wafer cleaning method and the cleaning apparatus will be described.
First, since the cleaning liquid is ejected from the ejection port 2 disposed on the side of the block-shaped wafer W ′ held in the air by the holding means 1 toward the gap G between the wafers W, resistance is higher than in the liquid. The flow rate of the cleaning liquid can be increased with a small amount, and the cleaning liquid smoothly flows into the gap G between the wafers W even in the block state, and also flows between the partially adhered wafers W for cleaning.

In order to confirm such an action, the wafer obtained by cleaning the block-shaped wafer by the above-described wafer cleaning method of the present invention and the block-shaped wafer sliced with the plate-shaped holder adhered are immersed in a cleaning tank to be super Experiments were performed comparing wafers cleaned by conventional wafer cleaning methods that perform sonic cleaning and rocking.
The result of this experiment is shown in FIG.

As a condition for this experiment, in the wafer cleaning method of the present invention, tap water (city water) was used as a cleaning liquid, and 20 liters per minute was sprayed in a room temperature environment to perform nozzle cleaning of the block-shaped wafer.
In order to make the conditions close to this, the conventional wafer cleaning method uses a surfactant as the cleaning liquid, circulates 20 liters per minute in an environment of 50 ° C., and adds ultrasonic vibration and oscillation of 40 kHz. The wafer was cleaned.

  With these cleaning methods, the cleaning of the block-like wafers in which dirt remains is similarly started, and after a predetermined time has passed, each block-like wafer is taken out and its cleaning state is photographed. Each photograph is shown in each column of FIG. It shows.

As a result, in the wafer cleaning method of the present invention, a desired cleaning degree was obtained when the cleaning time reached 30 minutes.
On the other hand, in the conventional wafer cleaning method, a desired cleaning degree could not be obtained even if the cleaning time passed 60 minutes. Further, 240 minutes were required to obtain the same cleaning result as the wafer cleaning method of the present invention.
As a result, it has been demonstrated that even if the gap G between the wafers W is very narrow, the wafers W can be efficiently cleaned without causing dropping or damage.

Further, as shown in FIGS. 2 and 3, the cleaning water is sprayed while moving the nozzle as the ejection port 1 along the side surface of the block-shaped wafer W ′ from the wafer bonding side W1 toward the wafer free end W2. The cleaning liquid spreads uniformly over the entire gap G.
Therefore, there is an advantage that the degree of cleaning can be further improved.

In particular, as shown in FIG. 5, if the spraying force of the cleaning liquid is increased by reducing the width dimension of the front end port 2 b of the ejection port 2 with respect to the length dimension in the wafer arrangement direction Y, the cut wafers W are several dozen. It has been experimentally found that even if the wafers are in close contact with each other, the gaps between the wafers W that are in close contact with each other can be forcedly expanded and cleaned, and the gap G between the original wafers W can be expanded several times.
Therefore, there is an advantage that the wafer W can be efficiently cleaned without dropping off or damaging the wafer W.

  In the second embodiment, as shown in FIG. 7, one nozzle 2c longer than the entire length Y of the wafer arrangement direction is provided at the position facing the side surface Wa 'of the block-shaped wafer W' as the ejection port 2. Unlike the first embodiment shown in FIGS. 1 to 5, the configuration in which the nozzle 2c is reciprocated only in the wafer axial direction X from the wafer bonding side W1 to the wafer free end W2 is different from the first embodiment shown in FIGS. Is the same as that of the first embodiment shown in FIGS.

  Accordingly, the embodiment shown in FIG. 7 not only obtains the same operational effects as the first embodiment shown in FIGS. 1 to 5 described above, but also the jet nozzle 2 as in the first embodiment shown in FIGS. Since there is no need to reciprocate the wafer in the wafer arrangement direction Y, the cleaning time can be shortened compared to the first embodiment, and the moving mechanism (not shown) of the jet nozzle 2 can be simplified.

In the illustrated example, the shape of the wafer W to be cleaned is a substantially circular shape in which the orientation flat OF is cut out. However, the shape is not limited to this, and a plate-like holder is provided on one side surface of the rod-shaped ingot. As long as the wafer W is cut and separated with a cutting machine such as a wire saw with H bonded, even a round wafer without an orientation flat OF or a rectangular wafer can be applied.
Further, the structure of the wafer cleaning apparatus is not limited to the above-described structure, and may have another structure as long as it has a similar function.

In the previous embodiment, only one ejection port 2 is provided to face one of the side surfaces Wa ′ of the block-shaped wafer W ′. However, the present invention is not limited to this, and a plurality of the plurality of side surfaces Wa ′ are opposed to each other. It is also possible to dispose a jet of cleaning liquid from the plurality of jets toward each side surface Wa ′, or to jet them at different timings.
Furthermore, after the nozzle 2 is cleaned by spraying a cleaning liquid such as a chemical solution from the jet nozzle 2, it is immersed in a warm water cleaning tank and subjected to ultrasonic cleaning or rocking in order to wash off the chemical or the like. You may make it complete | finish a washing | cleaning process and transfer to the subsequent drying process and peeling process.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the wafer cleaning method and apparatus which show one Example of this invention, (a)-(c) has shown the example of a different arrangement | positioning with a block-shaped wafer and a jet nozzle. It is explanatory drawing which shows an example of a washing | cleaning procedure, (a) is a front view, (b) is a side view. It is a front view which shows the other example of a washing | cleaning procedure. It is a side view at the time of arrange | positioning a jet nozzle close to a block-shaped wafer. It is a front view at the time of raising the injection power of cleaning liquid. It is a table | surface which shows a washing | cleaning comparison result. It is explanatory drawing of the wafer cleaning apparatus and apparatus which show the other Example of this invention, (a) is a front view, (b) is a side view.

Explanation of symbols

W Wafer W ′ Block-shaped wafer Wa ′ Side surface W1 Wafer bonding side W2 Wafer free end G Gap H Plate-shaped holder X Wafer axial direction Y Wafer arrangement direction 1 Holding means 2 Spout 2a Hose 2b Tip port 2c Nozzle

Claims (3)

One side surface of a rod-shaped ingot made of a semiconductor material is bonded to a plate-shaped holder (H) and cut and separated into a plurality of wafers (W), and gaps (G) between the cut and separated wafers (W) are formed. In the wafer cleaning method of cleaning while adhering to the plate-shaped holder (H),
A block-shaped wafer (W ′) bonded to the plate-shaped holder (H) is held in the air, and from the side of the block-shaped wafer (W ′) to the gap (G) between the wafers (W). A wafer cleaning method, wherein a cleaning liquid is jetted toward the wafer. One side surface of a rod-shaped ingot made of a semiconductor material is bonded to a plate-shaped holder (H) and cut and separated into a plurality of wafers (W), and gaps (G) between the cut and separated wafers (W) are formed. In a wafer cleaning apparatus for cleaning while adhering to a plate-shaped holder (H),
A holding means (1) for holding the block-shaped wafer (W ′) to which the plate-shaped holder (H) is bonded in air is provided, and a cleaning liquid jet is formed on the side of the block-shaped wafer (W ′). A wafer cleaning apparatus, wherein (2) is disposed toward a gap (G) between wafers (W). The nozzle (2) is a nozzle for injecting cleaning water, and this nozzle is arranged along the side surface (Wa ') of the block-shaped wafer (W') from the wafer bonding side (W1) to the wafer free end (W2). The wafer cleaning apparatus according to claim 1, which is moved toward