JP2001291689A - Polishing apparatus for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily strip a wafer held on a holding member stuck to a holding board by the surface tension of liquid, while suppressing variations in stripping time. SOLUTION: The polishing apparatus for wafer comprises a holding member 12 stuck to a rotatable holding board 10 and holding a wafer 20 by the surface tension of water, and a guide ring 14 fixed to the surface of the holding member to surround the wafer and preventing slippage of the wafer, where the surface of the wafer is mirror surface polished by pressing the surface of the wafer held on the surface of the holding member against the polishing face of a surface plate with a prescribed load and causing the holding board and the surface plate to move relatively. The polishing apparatus further comprises nozzles 30, 30, 30 for ejecting water towards the gap between the outer circumferential edge of the wafer fixed to a rotating holding board and the inner circumferential edge of the guide ring, at stripping of the mirror surface polished wafer from the surface of the holding member, and an oscillator horn for irradiating ultrasonic waves to the jet water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for a wafer, and more particularly, to a holding plate rotatably provided by a rotating device, and attached to the surface of the holding plate, and the surface of which is coated with water or the like. A holding member that holds the liquid by surface tension, and a guide ring that is mounted on the surface of the holding member so as to surround the periphery of the wafer and that prevents the wafer from sliding, and is held on the surface of the holding member. The present invention relates to a wafer polishing apparatus that presses a surface of a wafer thus set against a polishing surface of a surface plate with a predetermined load, and that relatively moves the holding plate and the surface plate to mirror-polish the surface of the wafer.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become higher in density and higher in integration, there has been a demand for smaller and thinner semiconductor devices. For this reason, a silicon wafer for a semiconductor device (hereinafter simply referred to as a wafer) serving as a base of the semiconductor device
Are further thinned, and the flatness of the surface is required to be even more accurate. Conventionally, to obtain such a wafer, a wafer cut from a columnar silicon single crystal is polished in a plurality of polishing steps to obtain a wafer having a predetermined thickness and flatness. By the way, since the wafer is thinned and the surface is mirror-finished in the polishing process at the later stage, it is necessary to handle the wafer with care. FIG. 8 shows a wafer polishing apparatus used in the subsequent polishing step. The wafer polishing apparatus includes a holding plate 1 rotatably provided in a direction indicated by an arrow by a rotating device (not shown) such as a motor.
0 and the wafer 2 is stuck on the surface of the holding plate 10 and
And a guide ring 14 attached to the surface of the holding member 12 so as to surround the periphery of the wafer 20 to prevent the wafer 20 from sliding. And

In this polishing apparatus, a wafer 20 mounted on a holding plate 10 is pressed against a polishing surface of a polishing cloth 42 stuck on a surface of a surface plate 40 with a predetermined load, and the rotation direction of the holding plate is the same. By rotating the plate 10 and the platen 40, the surface of the wafer 20 is mirror-polished. Here, when the wafer 20 is vacuum-sucked to the holding plate 10 without using the holding member 12, polishing is performed in a state where the corresponding portion of the wafer 20 is sucked into the suction holes 50 formed in the holding plate 10, as shown in FIG. Attached to For this reason, since the suction portion of the wafer 20 is not polished, the polished wafer 2 is not polished.
0 means that the flatness of the polished surface is reduced.

The wafer 20 that has been mirror-polished using the polishing apparatus shown in FIG. 8 needs to be separated from the holding plate 10 after the polishing is completed. It is held on a holding board 10. Therefore, if the wafer 20 is physically separated by a jig or the like, the polished surface of the wafer 20 may be damaged, or the wafer 20 may be damaged. For this reason, Japanese Unexamined Patent Publication No. Hei 8-1509 discloses that water is sprayed toward a gap between the outer peripheral edge of the wafer 20 mounted on the holding plate 10 and the inner peripheral edge of the guide ring 14 as shown in FIG. A wafer polishing apparatus provided with an injection nozzle 30 has been proposed.

[0005]

In the wafer polishing apparatus shown in FIG. 10, the peeling of the wafer 20 from the holding plate 10 after the mirror polishing is completed can be performed by spraying water from a water spray nozzle 30. Damage to the polished surface of the wafer 20 can be prevented as much as possible. However, FIG.
It has been found that in the wafer polishing apparatus shown in (1), the peeling time of the wafer 20 tends to vary, and the adjustment of the tact time in each polishing step in a plurality of polishing steps becomes complicated. Therefore, an object of the present invention is to provide a wafer which can easily peel a wafer held by a surface tension of a liquid such as water on a holding member attached to a holding board, and which can minimize variations in the peeling time. An object of the present invention is to provide a polishing apparatus.

[0006]

As a result of repeated studies to solve the above-mentioned problems, the present inventor has found that when a wafer is separated from the surface of a holding member, the wafer is held on a rotating holding plate by the surface tension of water. By spraying water while irradiating ultrasonic waves toward the gap between the outer periphery of the wafer and the inner periphery of the guide ring, the wafer can be easily peeled from the holding member, and variations in the peel time are possible. The present inventors have found that the number can be reduced as much as possible, and reached the present invention. That is, the present invention provides a holding plate rotatably provided by a rotating device, and a holding member made of a soft material such as polyurethane which is attached to the holding plate and holds a wafer on the surface thereof by surface tension of a liquid such as water. And a guide ring mounted on the surface of the holding member so as to surround the periphery of the wafer, and a guide ring for preventing sliding movement of the wafer, wherein the surface of the wafer held on the surface of the holding member is In a wafer polishing apparatus that presses against a polishing surface with a predetermined load and relatively moves the holding plate and the platen to mirror-polish the surface of the wafer, peels off the mirror-polished wafer from the surface of the holding member. A liquid such as water toward the gap between the outer peripheral edge of the wafer mounted on the holding plate being rotated by the rotating device and the inner peripheral edge of the guide ring. A liquid injection nozzle that is in the polishing apparatus of the wafer, characterized in that the ultrasonic irradiation means is provided for irradiating ultrasonic waves to the liquid.

In the present invention, a plurality of liquid jet nozzles are provided along the guide ring so as to jet liquid from a plurality of locations toward a gap between an outer peripheral edge of the wafer and an inner peripheral edge of the guide ring. Thereby, the position adjustment of each of the liquid ejection nozzles can be facilitated. Furthermore,
In order to irradiate ultrasonic waves to the liquid ejected toward the gap between the outer peripheral edge of the wafer and the inner peripheral edge of the guide ring, a vibrator horn for generating ultrasonic waves is provided in the liquid jet nozzle, or rotated by a rotating device. In order to irradiate ultrasonic waves to the liquid in which the holding member mounted on the holding plate and the wafer are immersed, ultrasonic vibrator horns for generating ultrasonic waves are provided in the liquid storage tank, so that the outside of the wafer is provided. Ultrasonic waves can be suitably applied to the liquid ejected toward the gap between the peripheral edge and the inner peripheral edge of the guide ring. Further, when peeling the wafer from the surface of the holding member, in order to peel a part of the holding member from the holding plate, by providing a flow path through which a fluid can be injected between the holding plate and the holding member, Further, the wafer can be easily peeled off.

In order to peel off a mirror-polished wafer held by a holding member made of a soft material such as polyurethane adhered to a holding plate by the surface tension of a liquid such as water, the surface tension of the liquid must be destroyed. is necessary. In the wafer polishing apparatus proposed in the above-mentioned patent publication, the surface tension holding the wafer is not destroyed by the liquid ejected from the liquid ejecting nozzle. However, the width of the gap between the outer peripheral edge of the wafer and the inner peripheral edge of the guide ring is not constant, and the liquid ejected from the liquid ejecting nozzle may not be sufficiently ejected to a desired portion. Also, depending on conditions such as the surface condition of the holding member, there is variation in the surface tension holding the wafer, and the surface tension holding the wafer may not be sufficiently destroyed with only the ejected liquid. It is presumed that the peeling time varies. In this regard, in the present invention, while rotating the wafer, a liquid such as water is jetted from the liquid jet nozzle toward the gap between the outer peripheral edge of the wafer and the inner peripheral edge of the guide ring, and the jetted liquid is irradiated with ultrasonic waves. By doing so, it is possible to reliably inject the liquid between the holding member made of a soft material such as polyurethane and the wafer.
As a result, the surface tension holding the wafer can be reliably reduced, and the wafer can be separated from the holding member. Therefore, the mirror-polished wafer can be easily separated from the holding member without damaging the polished surface,
In addition, variations in the peeling time can be reduced as much as possible.

[0009]

FIG. 1 shows an example of a wafer polishing apparatus according to the present invention. The wafer polishing apparatus shown in FIG. 1 includes a holding plate 10 rotatably provided by a rotating device such as a motor, and a polyurethane or the like which is attached to the holding plate 10 and holds the wafer 20 on the surface by the surface tension of water. The holding member 12 made of a soft material is provided. The holding member 12 is also called a backing material, and for example, a microporous sheet made of a soft material mainly composed of polyurethane can be used. The holding member 12 is bonded to one surface of the holding plate 10 with an adhesive, and holds the wafer 20 by the surface tension of water contained in the fine holes and the like. When a force is applied to the wafer 20 held by the holding member 12 by the surface tension of water in a direction parallel to the bonding surface of the holding member 12 to the wafer 20, the wafer 20 easily slides (slides). A guide ring 14 is attached to the surface of the holding member 12 so as to surround the periphery of the wafer 20.

As shown in FIG. 8, the wafer 20 mounted on the holding plate 10 is pressed against the polishing surface of the polishing cloth 42 stuck on the surface of the platen 40 with a predetermined load, as shown in FIG. By rotating the holding plate 10 and the platen 40 in the same direction at different rotation speeds, the surface of the wafer 20 is mirror-polished. In order to separate the wafer 20 after the mirror polishing from the holding member 12 of the holding plate 10, the wafer polishing apparatus shown in FIG. 1 includes a wafer 20 mounted on the holding plate 10 rotated by a rotating device such as a motor. A water jet nozzle 30 serving as a liquid jet nozzle for jetting water, preferably pure water, toward a gap between the outer peripheral edge of the guide ring 14 and the inner peripheral edge of the guide ring 14, and ultrasonic irradiation means for irradiating the jetted water with ultrasonic waves. Is provided. This ultrasonic irradiation means includes an ultrasonic generator 34 and, as shown in FIG.
The vibration generated by the ultrasonic generator 34 is transmitted to the vibrator horn 38 and the jet water is irradiated with ultrasonic waves.

As described above, the case 36 of the water injection nozzle 30
By rotating the holding plate 10 while irradiating the jet water jetted from the water jet nozzle 30 with ultrasonic waves by the vibrator horn 38 provided therein, variations in the peeling time of the wafer 20 can be reduced. That is, as described above, since the wafer 20 may slide on the holding member 12, the gap width between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 is likely to change. For this reason, the holding plate 10
Is stopped and one water injection nozzle 30 is provided, the water injection nozzle 30 is provided only at the point where the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 are in contact or extremely narrow. When water is sprayed, water is not sufficiently sprayed into the gap between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14, and the peeling time of the wafer 20 becomes longer. This is one of the causes of variation.

In this regard, when the wafer 20 is rotated, even if the wafer 20 slides sideways, water is formed at a place where the gap between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 is formed wider than the others. Since the water can be reliably injected from the injection nozzle 30, the variation in the peeling time of the wafer 20 can be reduced. In particular, as shown in FIG. 1, by providing a plurality of water injection nozzles 30, 30, 30 along the guide ring 14, in conjunction with rotating the holding plate 10, the separation time of the wafer 20 can be reduced. Variation can be further reduced. That is, water is repeatedly discharged from the plurality of water injection nozzles 30, 30, 30 where the gap between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 is formed wider than the other due to the side slip of the wafer 20 or the like. This is because water can be more reliably infiltrated between the wafer 20 and the holding member 12 made of a soft material such as polyurethane by being sprayed. Here, the tip of the water injection nozzle 30, the outer peripheral edge of the wafer 20, and the guide ring 14
Is preferably about 1 to 5 cm. In FIG. 1, the connection between the ultrasonic generator 34 and the water injection nozzles 30, 30 and the like are omitted.

The water injection nozzles 30, 30, 30 shown in FIG.
As shown in FIG. 3, each of them is held on an upright plate 52 erected on a base 50 so as to be adjustable in angle. Bolts 57a and 57b projecting from two places of the holder 56 are fitted into the arc-shaped slit 54 formed in the standing plate 52, and the bolts 57a and 57b are fitted on the back side of the standing plate 52. The wing nut is screwed. The water injection nozzle 30 can be fixed at a predetermined angle by tightening the wing nut. A wet station 60 is provided on the base 50 and receives and temporarily holds the wafer 20 peeled from the holding member 12 of the holding board 10. The wet station 60 is filled with water to reduce the impact of the peeled wafer 20.

The angle of the water jet nozzle 30 shown in FIG. 3 is adjusted so that water is jetted over the entire circumference of the gap between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14. However, as described above, the gap width is not constant because the wafer 20 slides sideways. Also, due to the thickness of the guide ring 14 and the like, the gap between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 may not be adjusted so that water is sprayed over the entire circumference. . In such a case, the angle of the water jet nozzle 30 is adjusted so that water is jetted onto the orientation flat 22 shown in FIG. 4A and the notch 24 shown in FIG. It may be adjusted. This part is wafer 2
0 slides and the outer peripheral edge of the wafer 20 and the guide ring 1
4 is a portion where a gap is always formed even if the inner peripheral edge of the base member 4 abuts. In addition, the end faces 22a (24a) and 22b (24) of the orientation flat 22 and the notch 24 are formed.
Also in FIG. 5B, chamfering is performed as shown in FIG. 5, so that water can reliably enter between the holding member 12 and the wafer 20.

In the wafer polishing apparatus shown in FIG. 1, a microporous sheet mainly made of polyurethane, which is used as the holding member 12, is adhered to the entire surface of the holding plate 10 with an adhesive. I have. By the way, this microporous sheet is a member that is substantially difficult to transmit a fluid such as air or water. For this reason, as shown in FIG. 6, the compressed air flow path 26, which can inject compressed air between the holding plate 10 and the holding member 12, so that the central portion of the holding member 12 is separated from the surface of the holding plate 10. 26 .. are preferably formed on the holding plate 10. In this way, by injecting compressed air between the holding plate 10 and the holding member 12, the central portion of the holding member 12 is separated from the surface of the holding plate 10, so that the surface tension of water is applied to the surface of the holding member 12. Wafer 2 held by
Since the gap 28 is easily formed between the edge of the “0” and the holding member 12, the separation due to the jet water jetted from the water jet nozzle 30.30.30 can be further facilitated.
In addition, in the wafer polishing apparatus shown in FIG. 6, it is preferable that water is sprayed from the water spray nozzles 30, 30, 30,.

The ultrasonic irradiating means in the wafer polishing apparatus shown in FIGS. 1 and 6 irradiates the jet water with ultrasonic waves by vibrator horn 38 provided in case 36 of water jet nozzle 30. However, as shown in FIG. 7, the holding member 12 mounted on the holding plate 10 and the wafer 20 are immersed in the storage water 46 stored in the storage tank 44, and the vibration provided at the bottom of the storage tank 44 is provided. Ultrasonic waves may be applied to the stored water 46 by the child horn 39. In this case, the holding plate 10 is rotated in the direction of the arrow while irradiating the stored water 46 with ultrasonic waves by the vibrator horn 39, and water is sprayed from the water injection nozzle 48 to the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14. Injects toward the gap. A vibrator horn need not be provided in the water injection nozzle 48. This is because the water injected from the water injection nozzle 48 into the storage tank 44 can be immediately irradiated with ultrasonic waves by the vibrator horn 39. As described above, even when the holding member 12 and the wafer 20 are immersed in the stored water 46, the holding plate 10 needs to be rotated. The gap width between the outer peripheral edge of the wafer 20 and the inner peripheral edge of the guide ring 14 tends to change.
Therefore, when the holding plate 10 is stopped, the wafer 2
When water is jetted from the water jet nozzle 48 only at a point where the outer peripheral edge of the zero and the inner peripheral edge of the guide ring 14 are in contact with or extremely narrow, the outer peripheral edge of the wafer 20 and the inner part of the guide ring 14 Water is not sufficiently injected into the gap with the peripheral edge, and the peeling time of the wafer 20 becomes longer. In addition, it is preferable to use pure water as the water injected from the stored water 46 and the water injection nozzle 48.

[0017]

According to the present invention, it is possible to easily peel off a mirror-polished wafer without damaging the wafer, and to minimize variations in the peeling time. For this reason,
The tact time of each polishing step in the polishing step of a plurality of wafers can be easily adjusted, and the wafer can be easily polished.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a wafer polishing apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating a water injection nozzle used in FIG.

3 is a partial cross-sectional front view illustrating the wafer polishing apparatus shown in FIG. 1 equipped with a water injection nozzle.

FIG. 4 is a front view illustrating a wafer and a guide ring mounted on a holding board.

FIG. 5 is a partial sectional view illustrating a state of an end face of an orientation flat or a notch of a wafer.

FIG. 6 is a schematic view illustrating another example of the wafer polishing apparatus according to the present invention.

FIG. 7 is a schematic diagram illustrating another example of the wafer polishing apparatus according to the present invention.

FIG. 8 is a schematic diagram illustrating an outline of a general wafer polishing apparatus.

FIG. 9 is a partial cross-sectional view illustrating a state of a wafer vacuum-adsorbed to a holding board.

FIG. 10 is a schematic view illustrating a conventional wafer polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Holding board 12 Holding member 14 Guide ring 20 Wafer 22 Orientation flat 24 Notch 26 Compressed air flow path 30, 48 Water injection nozzle 34 Ultrasonic generator 36 Case 38, 39 Transducer horn 44 Storage tank 46 Storage water

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Hasegawa 1650 Kiyono, Matsushiro-machi, Nagano-shi, Nagano F-term in Fujikoshi Machinery Co., Ltd. F-term (reference)

Claims (5)

[Claims] 1. A holding plate rotatably provided by a rotating device, and a holding member made of a soft material such as polyurethane adhered to the holding plate and holding a wafer on a surface thereof by a surface tension of a liquid such as water. A guide ring mounted on the surface of the holding member so as to surround the periphery of the wafer and preventing sliding movement of the wafer, and polishing the surface of the wafer held on the surface of the holding member to a surface plate. A wafer polishing apparatus for pressing a predetermined load against a surface and mirror-polishing the surface of a wafer by relatively moving the holding plate and the surface plate, wherein the mirror-polished wafer is separated from the surface of the holding member. At this time, a liquid such as water is jetted toward a gap between the outer peripheral edge of the wafer mounted on the holding plate being rotated by the rotating device and the inner peripheral edge of the guide ring. An injection nozzle, the polishing apparatus of the wafer, characterized in that the ultrasonic irradiation means for irradiating ultrasonic waves to the liquid is provided. 2. A plurality of liquid ejecting nozzles are arranged along the guide ring so that liquid is ejected from a plurality of places toward a gap between an outer peripheral edge of the wafer and an inner peripheral edge of the guide ring. The wafer polishing apparatus according to claim 1. 3. A vibrator horn for generating ultrasonic waves is provided in a liquid ejecting nozzle so that ultrasonic waves are applied to a liquid ejected toward a gap between an outer peripheral edge of a wafer and an inner peripheral edge of a guide ring. The wafer polishing apparatus according to claim 1 or 2, wherein 4. A vibrator horn for generating ultrasonic waves, wherein ultrasonic waves are applied to a liquid in which a holding member mounted on a holding plate rotated by a rotating device and a wafer are immersed in the liquid. 3. The wafer polishing apparatus according to claim 1, wherein the apparatus is provided in a storage tank. 5. A flow path capable of injecting a fluid into a gap between the holding plate and the holding member such that a part of the holding member is separated from the holding plate when the wafer is separated from the surface of the holding member. The wafer polishing apparatus according to any one of claims 1 to 4, wherein: