JP3455907B2 - Semiconductor wafer spin cleaning equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spin cleaning apparatus for a semiconductor wafer, which cleans a semiconductor wafer by suction-fixing it to a vacuum suction pad at the upper end of a spin shaft and rotating it at a high speed together with the spin shaft.

[0002]

In the manufacturing process of a semiconductor wafer, the semiconductor wafer sliced from the ingot is usually after the duplex is grinding, at least one side of the predetermined order of 700 mu m is polished mirror-finished thickness Is formed. Subsequently, each semiconductor wafer is cleaned by being sprayed with pure water while being rotated at a high speed by a spin cleaning device, and dried by being sprayed with dry air. Then, each semiconductor wafer has an IC circuit formed on one surface that is finished to have a mirror surface, and then is diced into a large number of chips.

Here, in the case of manufacturing an extremely thin chip having a thickness of 100 μm or less that can be incorporated in an IC card or the like as the chip, generally, an IC circuit before being diced into a large number of chips is formed. For semiconductor wafers,
Back-grinding is performed to grind the other surface on which no IC circuit is formed again to finish an extremely thin semiconductor wafer of 100 μm or less.

The back grinding process is performed by attaching a protective film to one side of a semiconductor wafer having an IC circuit formed thereon. Then, the back surface of the semiconductor wafer which has been subjected to the back grinding process is rotated at a high speed by the spin cleaning device, and the grinding surface and the surface of the protective film are cleaned by spraying pure water and dried by spraying dry air. Thereafter, the semiconductor wafer is diced into a large number of ultrathin chips with the protective film peeled off.

Here, in the conventional spin cleaning apparatus for cleaning and drying each semiconductor wafer after the polishing process and the back grinding process, a spin shaft rotated at a high speed by a motor and a central portion of the lower surface of the semiconductor wafer are fixed by suction. As described above, the vacuum suction pad fixedly provided on the upper end of the spin shaft, and the pure water is sprayed onto the upper surface of the semiconductor wafer whose central portion on the lower surface is suction-fixed to the vacuum suction pad and which is rotated at high speed by the rotation of the spin shaft. A pure water jet nozzle and an air jet nozzle for jetting dry air onto the upper surface of the semiconductor wafer are provided. A spin cleaning device of this type is disclosed in, for example, Japanese Patent Laid-Open No. 2000-
It is also described in the published patent publication of 58497.

[0006]

By the way, the back-grinded ultra-thin semiconductor wafer having a thickness of 100 μm or less is sucked and fixed to the vacuum suction pad of the spin cleaning apparatus only at the center of the lower surface thereof. Then, the outer peripheral portion is easily bent by its own weight. In addition, such an ultrathin semiconductor wafer is apt to warp due to strain caused by IC fabrication, back grinding, film tension, and the like. In particular, in the case of a semiconductor wafer having a large diameter of about 8 to 12 inches, the bending and warpage of the outer peripheral portion becomes large due to its own weight. Therefore, in a conventional spin cleaning apparatus, it is practically difficult to spin-fix an ultrathin, large-diameter semiconductor wafer on a vacuum suction pad and rotate the spin shaft at a high speed for spin cleaning.

However, by increasing the diameter of the vacuum suction pad, it is possible to prevent the outer peripheral portion from bending and warping even for an extremely thin semiconductor wafer having a large diameter, and spin cleaning can be performed by rotating the spin shaft at a high speed. It is possible. However, in this case, since the vacuum suction pad covers substantially the entire lower surface of the semiconductor wafer, there is a disadvantage that the lower surface of the semiconductor wafer cannot be sufficiently cleaned.

Therefore, according to the present invention, even for a semiconductor wafer having an extremely thin thickness and a large diameter, the vacuum suction pad is prevented from being increased in diameter, and the outer peripheral portion thereof is prevented from being bent or warped to rotate at high speed while being spin-cleaned. It is an object of the present invention to provide a spin cleaning apparatus for semiconductor wafers that can be used.

[0009]

As a means for solving the above-mentioned problems, the invention according to claim 1 is such that a central portion of a lower surface of a semiconductor wafer is suction-fixed to a vacuum suction pad provided at an upper end portion of a spin shaft, A spin cleaning apparatus for cleaning a semiconductor wafer while rotating the semiconductor wafer at a high speed by rotating the spin shaft, wherein air is jetted into a gap between the vacuum suction pad and the lower surface of the semiconductor wafer to fix the semiconductor wafer. An air jet pad for supporting the outer peripheral portion in a floating state is arranged around the vacuum suction pad, and the air jet pad is the vacuum suction pad.
It has a special feature that it can be retracted downward with respect to
To collect .

According to the first aspect of the present invention, in the spin cleaning apparatus for a semiconductor wafer according to the present invention, the vacuum suction pad provided on the upper end portion of the spin shaft sucks and fixes the central portion of the lower surface of the semiconductor wafer, the air injection pads arranged around the vacuum suction pad blown air in the gap between the lower surface of the semiconductor wafer outer peripheral portion of the semiconductor wafer supported on the floating state, the air injection pad the vacuum
It is provided so that it can be retracted downward with respect to the suction pad.
Then , move the air ejection pad downwards.
Under a semiconductor wafer placed on a vacuum suction pad.
Between the surface and the upper surface of the air ejection pad.
The insertion space can be formed, and the semiconductor wafer can be
It is possible to carry it in and out by placing it on the storage hand .

The invention as defined in claim 2 is as set forth in claim 1.
A spin cleaning apparatus for semiconductor wafers,
The air ejection pad should face the bottom surface of the semiconductor wafer.
Multiple air ejection holes along the circumference of the semiconductor wafer
And the plurality of air jets are
Concentric duplication for different types of semiconductor wafers
It is characterized in that it is arranged in a number sequence .

According to the second aspect of the invention, when a plurality of air ejection holes facing the lower surface of the semiconductor wafer are arranged in the air ejection pad along the circumferential direction of the semiconductor wafer, the outer periphery of the semiconductor wafer is formed. Can be supported in a uniform floating state. Furthermore, when the plurality of air ejection holes are arranged in a plurality of concentric rows on the air ejection pad corresponding to a plurality of types of semiconductor wafers having different diameters, even for a plurality of types of semiconductor wafers having different diameters. It is possible to support the outer peripheral portions of the respective parts in a uniform floating state.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spin cleaning apparatus for semiconductor wafers according to the present invention will be described below with reference to the drawings. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall structure of a spin cleaning apparatus for semiconductor wafers according to an embodiment, FIG. 2 is a cross-sectional view showing a main structure of the spin cleaning apparatus shown in FIG. 1, and FIG. FIG. 3 is a plan view of the air ejection pad shown in FIGS. 1 and 2.

As shown in FIG. 1, a spin cleaning apparatus 1 for a semiconductor wafer according to an embodiment of the present invention includes a support bracket 4 which is movably supported in a vertical direction with respect to a mounting base 2 through an elevating device 3. It is located above. In this spin cleaning apparatus 1, the central portion of the lower surface of the semiconductor wafer WH is suction-fixed to a vacuum suction pad 6 provided on the upper end of the spin shaft 5, and the semiconductor wafer WH is rotated while being rotated at a high speed by the rotation of the spin shaft 5. And a pure water spray nozzle 7 that sprays pure water as a cleaning liquid onto the upper surface of the semiconductor wafer WH, and an air spray nozzle 8 that sprays dry air onto the upper surface of the cleaned semiconductor wafer WH. .

The elevating device 3 serves as a mechanism for driving the support bracket 4 in the vertical direction, and a ball screw 3A rotatably installed in a posture substantially vertical to the mounting base 2 side, and is supported by being screwed onto the ball screw 3A. A ball nut 3B fixed to the bracket 4 side and a lifting motor 3C fixed to the mounting base 2 side to rotationally drive the ball screw 3A are provided. Further, as a mechanism for guiding the support bracket 4 in the vertical direction, a pair of left and right guide bars 3D installed on both sides of the ball screw 3A on the side of the mounting base 2 parallel to the ball screw 3A, and slidably fitted to the guide bars 3D. the fixed to the supporting bracket 4 side pair of right and left guide nut and
And 3E.

As shown in FIGS. 1 and 2, an upper stage support plate 4A and a lower stage support plate 4B are provided on the upper part of the support bracket 4 and are extended substantially horizontally with a predetermined space therebetween. And the upper support plate 4A
The spin shaft 5 of the spin cleaning device 1 is provided on the upper surface of
A cylindrical support holder 9 that rotatably supports the bearings BG, BG is detachably fixed by bolts B, B ... Through a mounting flange 9A that is integral therewith. A drive motor 10 for rotationally driving the spin shaft 5 is fixed to the lower surface of the lower support plate 4B with the rotation shaft 10A thereof facing upward.

The rotary shaft 10A of the drive motor 10 penetrates the lower support plate 4B and projects above it. The pulley transmission mechanism 1 is provided at the upper end of the rotary shaft 10A.
The drive pulley 11A forming part 1 is fixed. On the other hand, the lower end of the spin shaft 5 penetrates the upper support plate 4A together with the support holder 9 and projects below the support holder 9. A driven pulley 11B that constitutes the pulley transmission mechanism 11 is fixed to the lower end of the spin shaft 5. The transmission belt 11C is wound between the drive pulley 11A and the driven pulley 11B, so that the spin shaft 5 is driven to rotate at a high speed by the drive motor 10 at about 1000 to 2000 rpm.

The spin shaft 5 has a tubular shape with a vacuum supply port 5A connected to a negative pressure source such as a vacuum pump (not shown) provided at the lower end, and the upper end thereof projects above the support holder 9. . At the upper end of the spin shaft 5, a mounting base 5B for detachably fixing the vacuum suction pad 6 with a bolt B is provided. The mounting base 5B is fixed to the spin shaft 5 by an appropriate means such as welding, screw fitting in the direction opposite to the rotation direction of the spin shaft 5, or combined use of screw fitting and an adhesive. It may be machined integrally with 5. Then, the upper surface of the mounting base 5B is finished to be flush with the upper end surface of the spin shaft 5 so that the lower surface of the vacuum suction pad 6 can be evenly adhered thereto.

The vacuum suction pad 6 may be of any type as long as it can suction and fix the semiconductor wafer WH by the negative pressure supplied through the tubular spin shaft 5. For example, the lower surface of the semiconductor wafer WH may be formed of a metal block or the like having a suction hole or suction groove that exerts a suction negative pressure on the upper surface. In the spin cleaning apparatus 1 according to one embodiment, the diameter of the semiconductor wafer WH is 20 to 40 so that the central portion of the lower surface of the semiconductor wafer WH can be uniformly sucked and fixed.
The vacuum suction pad 6 is made of a porous material such as a sintered body of porous fine particles that is sintered in a circular block shape of about mm.

The pure water spray nozzle 7 is connected to a pure water spraying device (not shown), and the pure water is obliquely directed toward the upper surface of the semiconductor wafer WH whose center of the lower surface is suction-fixed to the vacuum suction pad 6. It is arranged so that it can be jetted. The air injection nozzle 8 is connected to a dry air injection device (not shown), and is arranged so as to obliquely inject the dry air toward the upper surface of the semiconductor wafer WH.

Pure water sprayed from the pure water spray nozzle 7 is prevented from scattering and the semiconductor wafer WH is
In order to prevent the pure water attached to the surface of the device from being scattered by the dry air sprayed from the air spray nozzle 8, the spin cleaning apparatus 1 according to one embodiment has a semiconductor suction-fixed to the vacuum suction pad 6. A splash cover 12 that surrounds the periphery of the wafer WH is provided. The splash cover 12 is formed in a substantially cylindrical shape, and an annular drain groove 12A is formed on the inner peripheral side of the lower end thereof. A drain pipe 12B is connected to the annular drain groove 12A.

Here, the semiconductor wafer WH of one embodiment
In the spin cleaning apparatus 1 of FIG.
An air jet pad 13 is provided around the vacuum suction pad 6 for jetting air into the gap between the lower surface center portion of the semiconductor wafer WH and the lower surface center portion of the semiconductor wafer WH to be sucked and fixed to support the outer peripheral portion of the semiconductor wafer WH in a floating state. Has been done. The air ejection pad 13 has a disk shape in which a boss portion 13A that fits on the outer periphery of the support holder 9 and is slidable in the vertical direction is provided so as to project downward, and has a boss hole 13B at the center thereof. The vacuum suction pad 6 and the mounting base 5B at the upper end of the spin shaft 5 are housed.

In order to control the position of the air ejection pad 13 between the upper operating position and the lower retracted position shown in FIG. 2,
An air cylinder 14 for raising and lowering operation is provided between the upper surface of the upper support plate 4A of the support bracket 4 and the lower surface of the outer peripheral portion of the air ejection pad 13 facing the upper support plate 4A. Here, the air ejection pad 13 is stopped at an upper operating position, and its upper surface is covered with the semiconductor wafer W.
In order to face the lower surface of the outer peripheral portion of H with a gap of about 10 to 100 μm, the upper end portion of the support holder 9 is slidably fitted into the boss hole 13B of the air ejection pad 13. The stopper 15 that engages with the step portion 13C of the boss hole 13B is fixed. The stopper 15 also serves as a cover of the bearing BG that rotatably supports the spin shaft 5 on the support holder 9.

The air ejection pad 13 has a plurality of air ejection holes 13D facing the lower surface of the semiconductor wafer WH.
Are formed. Each air ejection hole 13D is connected to an air pressure source such as an air compressor (not shown) via an air supply passage 16 attached to the lower surface of the air ejection pad 13.

The air ejection holes 13D of the air ejection pad 13 are arranged along the circumferential direction of the semiconductor wafer WH whose central portion is suction-fixed to the vacuum suction pad 6. Since the plurality of air ejection holes 13D correspond to a plurality of types of semiconductor wafers WH having different diameters of 8 to 12 inches, as shown in FIG.
It is arranged in a plurality of rows concentric with the three boss holes 13B.
And each air ejection hole 1 arranged in a plurality of concentric rows
3D is opened in each of a plurality of rows of annular grooves 13E formed concentrically on the upper surface of the air ejection pad 13.

The semiconductor wafer spin cleaning apparatus 1 of the embodiment having the above-described structure is used for cleaning the semiconductor wafer WH whose both surfaces are ground and then at least one surface is mirror-polished. In particular, it is suitably used for cleaning a semiconductor wafer having a large diameter of about 8 to 12 inches, which is back-grinded to have an extremely thin thickness of 100 μm or less. Semiconductor wafer WH to be cleaned
Is typically a silicon wafer, but GaAs
A compound semiconductor such as a (gallium / arsenic) wafer or a GaP (gallium / phosphorus) wafer, or a crystal for an extremely thin crystal oscillator, a single crystal for a solar cell, or a polycrystalline silicon wafer is also included.

In order to clean the semiconductor wafer WH by using the spin cleaning apparatus 1 of one embodiment, first, the lifting device 3 is used.
The ball screw 3A is normally driven by the lifting motor 3C to raise the support bracket 4, and the spin cleaning apparatus 1 is raised to the operating region of the robot hand RH indicated by the chain double-dashed line in FIG. Then, the air cylinder 14 is contracted to move the air ejection pad 13 downward with respect to the vacuum suction pad 6 and position it in the retracted position. Then, the robot hand RH supporting the lower surface of the semiconductor wafer is moved above the vacuum suction pad 6 of the spin cleaning apparatus 1, and the robot hand RH is lowered to the vacuum suction pad 6 side to spin-clean the semiconductor wafer WH. It is placed on the vacuum suction pad 6 of the device 1.

When the semiconductor wafer WH is placed on the vacuum suction pad 6 by lowering the robot hand RH, the semiconductor wafer WH is placed so that the center of the semiconductor wafer WH coincides with the center of the vacuum suction pad 6. At this time, the air jet pad 13
Since the upper surface of the robot is at a retracted position below the upper surface of the vacuum suction pad 6, it does not interfere with the robot hand RH.

After the semiconductor wafer WH is placed on the vacuum suction pad 6, the spin shaft 5 is attached to the vacuum suction pad 6.
By applying a suction negative pressure via the, the central portion of the lower surface of the semiconductor wafer WH is suction-fixed to the vacuum suction pad 6. Then, the robot hand RH is retracted from the spin cleaning device 1. Then, the air cylinder 14 is extended to move the air ejection pad 13 to the upper operating position. Then, the ball screw 3A is reversely driven by the lifting motor 3C of the lifting device 3 to lower the support bracket 4, and the spin cleaning device 1 is lowered to the working position shown by the solid line in FIG.

After such preparatory work, the air supply passage 1
6, while ejecting air through each air ejection hole 13D of the air ejection pad 13, the drive motor 10 drives the spin shaft 5 through the pulley transmission mechanism 11
Rotate at high speed at about 2000 rpm. In this state, the vacuum suction pad 6 provided on the upper end of the spin shaft 5 sucks and fixes the central portion of the lower surface of the semiconductor wafer WH, and the air ejection pad 13 arranged around the vacuum suction pad 6 is a semiconductor. Each air ejection hole 13D is provided in the gap of about 10 to 100 μm between the lower surface of the wafer WH and
Air is jetted from the outer peripheral portion of the semiconductor wafer WH to support it in a floating state.

Therefore, the pure water injection nozzle is applied to the semiconductor wafer WH which is rotated at a high speed together with the spin shaft 5 in a state where the central portion is sucked and fixed to the vacuum suction pad 6 and the outer peripheral portion is supported in a floating state by the air ejection pad 13. Pure water is sprayed from 7 to spin clean the upper surface of the semiconductor wafer WH, and then dry air is sprayed from the air spray nozzle 8 to dry the upper surface of the spin cleaned semiconductor wafer WH.

As described above, according to the spin cleaning apparatus 1 of the embodiment, the rotation of the spin shaft 5 allows the semiconductor wafer WH to rotate at a high speed with the outer peripheral portion thereof floating, and has a thickness of 100 μm. It is possible to spin-clean a semiconductor wafer WH having an extremely thin wall thickness of m or less and a diameter of about 8 to 12 inches while rotating it at a high speed while preventing the outer peripheral portion from being bent or warped due to its own weight. it can.

In particular, in the semiconductor wafer spin cleaning apparatus 1 of one embodiment, the air suction pad 13 is retracted to a position apart from the vacuum suction pad 6 by the contraction operation of the air cylinder 14, so that the vacuum suction is performed. The robot hand RH can be inserted between the lower surface of the semiconductor wafer WH placed on the pad 13 and the upper surface of the air ejection pad 13, and the semiconductor wafer WH can be loaded and unloaded on the robot hand RH. it can.

Further, since the plurality of air ejection holes 13D facing the lower surface of the semiconductor wafer WH are arranged on the air ejection pad 13 along the circumferential direction of the semiconductor wafer WH, the outer peripheral portion of the semiconductor wafer WH is uniformly floated. Can be supported in a state.

Further, since the plurality of air ejection holes 13D are arranged in a plurality of concentric rows on the air ejection pad 13 corresponding to the plurality of types of semiconductor wafers WH having different diameters, a plurality of types of different diameters are provided. Semiconductor wafer W
Even for H, the outer peripheral portions thereof can be supported in a uniform floating state.

Further, since the plurality of air ejection holes 13D are opened in the annular groove 13E formed on the upper surface of the air ejection pad 13, the air ejected from each air ejection hole 13D stays in the annular groove 13E. Therefore, the outer peripheral portion of the semiconductor wafer WH can be supported in a more uniform floating state.

Although not shown, a recess may be formed on the upper surface of the air ejection pad 13 instead of the annular groove 13E, and each air ejection hole 13D may be opened in this recess.

Further, the robot hand RH is not limited to the structure for supporting and carrying the lower surface of the semiconductor wafer WH, but may have a structure for sucking and carrying the upper surface of the semiconductor wafer WH. In this case, the robot hand RH does not interfere with the air ejection pad 13 and the vacuum suction pad 6
Since the semiconductor wafer WH can be carried in and out, the air ejection pad 13 does not have to be lowered by the air cylinder 14, and the air cylinder 14 can be omitted.

[0039]

According to the invention described in claim 1, in the spin cleaning apparatus for a semiconductor wafer according to the present invention, the vacuum suction pad provided on the upper end of the spin shaft suction-fixes the center of the lower surface of the semiconductor wafer. and, the air injection pads arranged around the vacuum suction pad by ejecting air into the gap between the lower surface of the semiconductor wafer to support the outer peripheral portion of the semiconductor wafer in floating state, the air injection pad said true
It is provided so that it can be retracted downward with respect to the empty suction pad.
If so, move the air ejection pad downwards.
Under a semiconductor wafer placed on a vacuum suction pad.
Between the surface and the upper surface of the air ejection pad.
It is possible to form the insertion space, Robo semiconductor c Eha
It is possible to carry it in and out by placing it on the storage hand .

According to the second aspect of the invention, the semiconductor window is
A plurality of air ejection holes facing the bottom surface of the wafer
Arranged on the air ejection pad along the circumference of the wafer.
The outer circumference of the semiconductor wafer in a uniform floating state.
Can be supported. Furthermore, the plurality of air jets
Supports multiple types of semiconductor wafers with different diameters
The air ejection pads are arranged in a plurality of concentric rows.
Then, for multiple types of semiconductor wafers with different diameters
Also, the outer periphery of the
You can

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall structure of a spin cleaning apparatus for semiconductor wafers according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main structure of the spin cleaning apparatus shown in FIG.

FIG. 3 is a plan view of the air ejection pad shown in FIGS. 1 and 2.

[Explanation of symbols]

1: Spin cleaning device 2: Mounting base 3: Lifting device 4: Support bracket 5: Spin shaft 6: Vacuum suction pad 7: Pure water injection nozzle 8: Air injection nozzle 9: Support holder 10: Drive motor 11: Pulley transmission mechanism 12: Splash cover 13: Air ejection pad 13A: Boss 13B: Boss hole 13C: Step 13D: Air ejection hole 13E: annular groove 14: Air cylinder 15: Stopper 16: Air supply path

Continuation of the front page (56) Reference JP 2002-43400 (JP, A) JP 9-64004 (JP, A) JP 7-78745 (JP, A) Actual Kaihei 3-73436 (JP, U) Actual development Sho 62-32533 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/304 B08B 3/02 B08B 5/02

Claims (2)

(57) [Claims] 1. A spin cleaning apparatus for a semiconductor wafer, in which a central portion of a lower surface of a semiconductor wafer is suction-fixed to a vacuum suction pad provided at an upper end portion of a spin shaft, and the semiconductor wafer is cleaned while being rotated at a high speed by rotation of the spin shaft. An air jet pad is provided around the vacuum suction pad for jetting air into a gap between the vacuum suction pad and the lower surface of the semiconductor wafer to support the outer peripheral portion of the semiconductor wafer in a floating state. The air jet pad is different from the vacuum suction pad.
Characterized by being provided so that it can be retracted downward
Spin cleaning system for semiconductor wafers . 2. The semiconductor wafer screen according to claim 1.
A pin cleaning device, wherein the air ejection pad has a half
Half of the air ejection holes facing the bottom surface of the conductor wafer are
Are arranged along the circumferential direction of the conductor wafer,
The number of air jets is equal to
Arranged in multiple concentric rows corresponding to the wafer
An apparatus for spin cleaning semiconductor wafers .