JP2001358096A - Thinning device and method of flat object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for thinning a flat object for removing a micro crack layer on the surface such as a wafer in a short unit time and with improved working efficiency. SOLUTION: A semiconductor wafer where a protection film is formed on a circuit surface is taken out of a wafer accommodation part 2 by a wafer transport part 3, is aligned by a pre-center part 5, and then is mechanically polished by a polishing part 6. The semiconductor wafer after polishing is washed with washing liquid by a wafer washing part 10 for removing foreign objects, and then is sent to first and second plasma treatment parts 4A and 4B slowly by the wafer transport part 3 so that the semiconductor wafer cannot be cracked for performing dry etching by plasma etching. When the etching is completed, the semiconductor wafer is carried out speedily from the first and second plasma treatment parts 4A and 4B by the wafer transport part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for thinning a plate-like body such as a semiconductor wafer.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor wafer used for a semiconductor device, a polishing process is performed to reduce the thickness of the semiconductor wafer as the semiconductor device becomes thinner. This polishing is performed by forming a circuit pattern on the front surface of the semiconductor wafer and then mechanically polishing the back surface opposite to the circuit formation surface. On the surface of the silicon substrate after mechanical polishing, there is a layer (microcrack-introduced layer) embrittled by microcracks formed by processing.
The microcracks impair the bending strength of the silicon substrate, and the silicon substrate is easily broken from the microcracks. Therefore, it is necessary to remove the microcrack-introduced layer on the silicon surface after mechanical polishing. Conventionally, the microcrack-introduced layer has been removed by wet etching using an etching solution such as hydrofluoric acid or nitric acid. However, as a means for removing the microcrack-introduced layer, a plasma processing apparatus may be used. Conventionally, a plasma processing apparatus has
A cleaning means for cleaning the surface of a work, such as a printed circuit board, has been proposed. A work, such as a printed circuit board, is housed between two electrode portions of a vacuum chamber, and a high-frequency voltage is applied between the electrode portions. By doing so, plasma is generated, and ions and the like are caused to collide with the surface of the electrodes on the printed circuit board to clean the electrodes.

[0003]

When the microcrack introduction layer is removed by using the microcrack removing means using a microcrack removing means such as a plasma processing apparatus, the following requirements (1) and (2) are satisfied. It is desirable to be done.

(1) When handling a plate-like body such as a wafer to remove the microcrack-introduced layer (for example, when carrying the plate-like body into a vacuum chamber of a plasma processing apparatus), Not crack from micro cracks.

(2) To improve the production efficiency, the entire process of removing the microcrack-introduced layer must be completed in as short a time as possible. For this purpose, the plate-like object should be put in and out of a processing space such as a vacuum chamber in as short a time as possible.

Accordingly, an object of the present invention is to provide an apparatus and a method for thinning a plate-like body capable of removing a micro-crack-introduced layer on the surface of a plate-like body such as a wafer in a short tact time with good workability. .

[0007]

According to a first aspect of the present invention, there is provided an apparatus for thinning a plate-like body, comprising: mechanical polishing means for mechanically polishing the plate-like body;
Microcrack removing means for removing microcracks formed on the surface of the plate by mechanical polishing by etching, and a first plate which carries the plate polished by the mechanical polishing means into the microcrack removing means. Body transporting means, and a second plate-like body transporting means for carrying out the plate-like body from which the microcracks have been removed by the microcrack removing means from the microcrack removing means, and the microcracks are removed by the microcrack removing means. The transport speed of the previous plate was made slower than the transport speed after the microcracks were removed by the microcrack removing means.

According to a second aspect of the present invention, there is provided an apparatus for thinning a plate-like body according to the first aspect of the present invention, wherein the same plate-like body transport means is provided with the first plate-like body transport. Means and the second plate-like body conveying means.

According to a third aspect of the present invention, there is provided an apparatus for thinning a plate-like body according to the first aspect, wherein the first plate-like body conveying means and the second plate-like body are provided. The transporting means has a plate-like body holding section that sucks and holds the plate-like body.

According to a fourth aspect of the present invention, there is provided an apparatus for thinning a plate-like body according to any one of the first to third aspects. A hand rotation mechanism for rotating the plate-like body holding unit is provided.

According to a fifth aspect of the present invention, there is provided a method of thinning a semiconductor wafer, wherein the step of mechanically polishing the plate-like body by mechanical polishing means and the step of micro-cracking the mechanically polished plate-like body by the first plate-like body transporting means. Carrying in the removing means, removing microcracks on the surface of the plate by the microcrack removing means, and removing the microcrack-removed plate from the microcrack removing means by the second plate-like transporting means. Transporting the plate-like body by the first plate-like body transporting means so as to be slower than the plate-like body transporting speed by the second plate-like body transporting means. I do.

According to a sixth aspect of the present invention, in the method of thinning a semiconductor wafer, the same plate-like body transfer means also serves as the first plate-like body transfer means and the second plate-like body transfer means.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer processing apparatus according to one embodiment of the present invention, FIG. 2 is a plan view of a semiconductor wafer processing apparatus according to one embodiment of the present invention, and FIGS. FIG. 5 is a perspective view of a wafer storage unit of the semiconductor wafer processing apparatus according to the embodiment; FIG. 5 is a partial plan view of the semiconductor wafer processing apparatus according to one embodiment of the present invention; Side view of a polishing unit of a wafer processing apparatus,
7 is a cross-sectional view of a wafer cleaning unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention, FIG. 8 is a cross-sectional view of a plasma processing unit of the semiconductor wafer processing apparatus of one embodiment of the present invention,
9 and 10 are process explanatory views of a semiconductor wafer processing method according to one embodiment of the present invention, FIG. 11 is a block diagram of a semiconductor wafer processing apparatus according to one embodiment of the present invention, and FIG. FIG. 2 is a flowchart of semiconductor wafer cleaning in the semiconductor wafer processing method according to one embodiment.

First, the overall structure of a semiconductor wafer processing apparatus which is a plate-like body will be described with reference to FIGS. In FIGS. 1 and 2, a wafer storage unit 2, a first plasma processing unit 4 </ b> A, a second plasma processing unit 4 </ b> B, and a pre-center unit Further, the wafer cleaning unit 10 is radially arranged.

The wafer storage section 2 stores semiconductor wafers before and after processing. That is, the wafer storage unit 2 serves as a storage unit of the semiconductor wafer. The first plasma processing unit 4A and the second plasma processing unit 4B perform dry etching on the surface of the semiconductor wafer by an etching action of plasma generated in a reduced-pressure atmosphere. Therefore, the first
The plasma processing unit 4A and the second plasma processing unit 4B
It serves as a means for dry etching a semiconductor wafer.

The pre-center unit 5 performs a pre-center operation for pre-positioning a semiconductor wafer to be transferred to a polishing unit 6 described later. The wafer cleaning unit 10 cleans the semiconductor wafer polished by the polishing unit 6 with a cleaning liquid. That is, the wafer cleaning unit 10 is a means for cleaning a semiconductor wafer.

A polishing section 6 is provided on the rear half 1b of the upper surface of the base section 1. The polishing unit 6 includes a wall 6a erected on the upper surface of the base 1, and a first polishing unit 8A and a second polishing unit 8B are disposed on the front side surface of the wall 6a. The first polishing unit 8A and the second polishing unit 8B perform rough polishing and finish polishing of the semiconductor wafer 11, respectively. That is, the polishing section 6 is a mechanical polishing means for mechanically polishing the semiconductor wafer 11. A turntable 7 is disposed below the first polishing unit 8A and the second polishing unit 8B, surrounded by the combing 6b. The turntable 7 rotates by an index, holds the semiconductor wafer 11 to be polished, and holds the first polishing unit 8.
A and the second polishing unit 8B.

On the front side of the polishing section 6, a wafer carrying-in section 9A and a wafer carrying-out section 9B are provided as plate-like body conveying means. The wafer carry-in unit 9A carries the semiconductor wafer positioned in the pre-center unit 5 into the polishing unit 6. The wafer unloading section 9B unloads the semiconductor wafer after mechanical polishing from the polishing section 6. Therefore, the above-described wafer transfer unit 3, wafer carry-in unit 9A, and wafer carry-out unit 9B serve as the semiconductor wafer 11 between the polishing unit 6, the wafer cleaning unit 10, the first plasma processing unit 4A, or the second plasma processing unit 4B. And a wafer handling means for supplying the semiconductor wafer 11 to the polishing unit 6 and taking out the dry-etched semiconductor wafer 11 from the first plasma processing unit 4A or the second plasma processing unit 4B.

Hereinafter, the configuration and function of each unit will be sequentially described. As shown in FIGS. 1 and 2, the wafer storage section 2 includes two magazines 2A and 2B for storing wafers. The magazines 2A and 2B store a large number of semiconductor wafers to be thinned. As shown in FIGS. 3 and 4, the magazines 2A and 2B have a structure in which shelf members 13 are provided in multiple stages inside a housing 12, and the semiconductor wafer 1 is placed on the shelf members 13.
1 is placed.

The semiconductor wafer 11 contains silicon as a main component, and has a plurality of semiconductor elements. A protective film 11a is formed on the circuit formation surface of the semiconductor wafer 11 (see FIG. 10B). The protective film 11a has a function of protecting the circuit pattern of the semiconductor wafer 11 and reinforcing the semiconductor wafer 11 to improve the bending strength. When the semiconductor wafer 11 is stored in the magazines 2A and 2B, the shelf member 1 is placed with the protective film 11a facing upward.
3 is placed.

In FIG. 2, a wafer transfer section 3 is provided in a recess 1c formed in the center of the first half 1a. On the base member 3a of the wafer transfer section 3, a robot mechanism of a polar coordinate system is provided. The base member 3a can be turned 360 degrees on the base part 1 by a drive mechanism (not shown), and the direction of the robot mechanism can be freely controlled. The wafer transfer section 3 is used for the semiconductor wafer 1
1 is a wafer storage unit 2, a first plasma processing unit 4A,
It is a plate-like body transport means for moving and taking in and out each work stage such as the plasma processing section 4B, the pre-center section 5, and the wafer cleaning section 10. In addition, the wafer transfer unit 3 of the present embodiment includes a first plate-shaped transfer unit that loads the semiconductor wafer 11 that has been mechanically polished by the mechanical polishing unit into the first plasma processing apparatus 4A and the second plasma processing apparatus 4B. The semiconductor wafer 11 from which the microcracks have been removed
And the second plate-like body transporting means for carrying out from the plasma processing apparatus 4A and the second plasma processing apparatus 4B, and also as the taking-in / out means for taking in and out of the pre-center section 5, the wafer cleaning section 10, and the like. ing.

The robot mechanism includes a second swing arm 14b and a first swing arm 14a extending in the lateral direction with respect to an arm shaft (not shown) which can be vertically extended and retracted on the base member 3a. The second rotating arm 14b is connected to a wafer holding portion 17 as a plate-shaped body holding portion. The wafer holding portion 17 is a forked fork-like member 17b having a suction hole 17a provided on the upper surface (FIG. 4).
), And is rotated around an axis by the hand rotation mechanism 15, and the inclination of the wafer holding unit 17 is controlled by the wrist mechanism 16. Further, by turning the first turning arm 14a and the second turning arm 14b, the wafer holder 17 can be moved forward and backward in the horizontal direction.

By driving each part of the robot mechanism, the wafer holding part 17 is provided with the wafers such as the magazines 2A and 2B, the first plasma processing part 4A, the second plasma processing part 4B, the pre-center part 5, and the wafer cleaning part 10. Move to the delivery target. Then, the semiconductor wafer 11 is held by the wafer holding unit 17 and the semiconductor wafer is transferred between the respective parts to be transferred.

That is, the wafer holder 17 can be turned in any direction by turning the base member 3a.
The swivel arm 14a and the second swivel arm 14b allow the wafer holding unit 17 to move forward in the horizontal direction to access the respective parts to be transferred. By driving the hand rotation mechanism 15, the wafer holding unit 1
The semiconductor wafer 11 (see FIG. 4), which is sucked and held by the suction holes 17a on the wafer 7, is turned upside down, and by driving an arm shaft (not shown), the wafer holding unit 17 moves up and down. As described above, by adopting a configuration in which the respective parts to be transferred are radially arranged around the wafer transfer unit 3 using the robot mechanism of the polar coordinate system, a plurality of wafer transfer targets can be transferred by a single robot mechanism. A compact semiconductor wafer processing apparatus that can be covered and has excellent work efficiency is realized.

The operation of taking out and storing the semiconductor wafer 11 from the magazines 2A and 2B by the wafer holding unit 17 will now be described. At the time of unloading, as shown in FIG. 3, the wafer holding unit 17 is inserted up to above the semiconductor wafer 11 stored in the magazine 2A (2B) with the suction hole 17a facing downward. Next, the wafer holding unit 1
The semiconductor wafer 11 is lowered and brought into contact with the upper surface of the semiconductor wafer 11, and in this state, the semiconductor wafer 11 is suction-held on the lower surface of the wafer holding portion 17 by vacuum suction from the suction holes 17 a. Thereafter, when the wafer holding unit 17 is raised again and pulled out of the magazine 2A (2B), the semiconductor wafer 11 is taken out while being held by suction on the lower surface of the wafer holding unit 17.

FIG. 4 shows a semiconductor wafer 11 in a magazine 2A.
(2B) shows the storing operation of returning the inside. In this storing operation, the semiconductor wafer 1 sucked and held from the upper surface side by the wafer holding unit 17 with the thinned surface facing upward.
1 is turned upside down by rotating the wafer holding unit 17 around an axis, and is stored in the magazine 2A (2B) with the protective film 11a facing upward. At this time, the same semiconductor wafer 11 is returned to the same position stored before processing.

This reinsertion is performed by inserting the wafer holding portion 17 holding the semiconductor wafer 11 on the upper surface into the magazine 2A (2B), releasing the vacuum suction, and then lowering the wafer holding portion 17. That is, in this lowering operation, as shown in FIG. 4, the fork-like member 17 b of the wafer holding unit 17 passes through the notch 13 a downward with the semiconductor wafer 11 placed on the shelf member 13. Then, the storage of the semiconductor wafer 11 is completed by pulling the wafer holding unit 17 out of the magazine.

Next, the pre-center unit 5 will be described with reference to FIG. The pre-center unit 5 is for positioning the semiconductor wafer 11 supplied to the polishing unit 6 in advance. In FIG. 5, a pre-center unit 5 is a circular mounting table 20.
It has. On the upper surface of the mounting table 20, there is formed a removed portion 21 (see hatched portion) whose upper surface is partially removed corresponding to the shape of the wafer holding portion 17, and the depth of the removed portion 21 is equal to the removed portion 21. The depth is set so that the wafer holding unit 17 can be accommodated therein.

The loading of the semiconductor wafer 11 into the pre-center unit 5 is performed as follows. First, the wafer holding unit 17 holding the semiconductor wafer 11 on the upper surface side is placed on the mounting table 20.
The horizontal position of the wafer holding unit 17 is moved upward to remove unit 2.
After that, the wafer holding unit 17 is lowered to a height position where the wafer holding unit 17 is accommodated in the removing unit 21. Thereby, the semiconductor wafer 11 is mounted on the mounting table 20. Thereafter, the wafer holding unit 17 is retracted from the inside of the removing unit 21 to complete the loading of the semiconductor wafer 11.

The mounting table 20 is provided with a plurality of grooves 22 radially toward the center at equal positions at 120 degrees, and each groove 22 is positioned so as to be movable in the groove direction. The claw 22a is provided. By moving the positioning claw 22a toward the center of the mounting table 20 while the semiconductor wafer 11 is mounted on the mounting table 20, the semiconductor wafer 11 is aligned with the center position of the mounting table 20. Is done. That is, the pre-center unit 5
This is a mounting section for mounting and positioning the semiconductor wafer 11 supplied to the polishing section 6.

The wafer loading section 9 is adjacent to the pre-center section 5.
A is provided. As shown in FIG. 5, the wafer carrying-in section 9A is configured by attaching a suction head 25A to a distal end of a transfer arm 24A that is turned and moved up and down by an arm driving mechanism 23. When the suction head 25A is moved over the semiconductor wafer 11 in the pre-center section 5 and lowered, the suction head 25A suction-holds the semiconductor wafer 11. Thereafter, the semiconductor wafer 11 is carried into the polishing unit 6 by moving the transfer arm 24A upward and turning in the direction of the polishing unit 6, and moves to a wafer delivery station (described later).

Next, the polishing section 6 will be described with reference to FIGS. The polishing section 6 will be described with reference to FIGS. As shown in FIGS. 2 and 6, a turntable 7 is provided on the upper surface of the base 1. The turntable 7 can be rotated around the center axis by an index.
Three chuck tables 7a are provided at equally spaced positions at 120 degrees as index positions.

Each chuck table 7a receives the semiconductor wafer 11 from the transfer arm 24A of the wafer loading section 9A at a wafer transfer station (the index position on the left side in FIG. 6). Chuck table 7a
The semiconductor wafer 11 adsorbs and holds the semiconductor wafer 11 on its upper surface, and is rotatable about the axis.

A first polishing unit 8A and a second polishing unit 8B are provided on the side surface of the wall 6a erected on the right end of the upper surface of the base unit 1. First polishing unit 8
A, the horizontal arrangement of the second polishing unit 8B corresponds to the index position of the turntable 7, respectively, and the lower index position of the first polishing unit 8A and the second polishing unit 8B is Each has a rough polishing station and a finish polishing station.

Each of the first polishing unit 8A and the second polishing unit 8B has a rotation drive unit 30 at the bottom. On the lower surface of the rotation drive unit 30, grindstones 31A and 31B for rough polishing or finish polishing for polishing the semiconductor wafer 11 are mounted. A grindstone of about # 500 is used for rough polishing, and generally # 3000 to # 4000 for finish polishing.
Is used. These first polishing units 8
A, the second polishing unit 8B is moved up and down by a built-in vertical movement mechanism.

As shown in FIG. 6, the chuck table 7a holding the semiconductor wafer 11 is moved to the first polishing unit 8A.
The grinding wheel 31A is moved to the index position (polishing position) below the (or second polishing unit 8B).
(Or 31B) is lowered and brought into contact with the upper surface of the semiconductor wafer 11, and the grindstone 31A (or 31B) is rotated by the rotation drive unit 30, whereby the semiconductor wafer 11 is rotated.
Is polished.

When the chuck table 7a is located at a polishing position below the first polishing unit 8A and the second polishing unit 8B, the chuck table 7a is rotated by a driving mechanism (not shown). I have. The rotation of the chuck table 7a and the grinding wheel 31
By combining the rotations of A and 31B, the upper surface of the semiconductor wafer 11 is uniformly polished without bias during polishing.

At the time of this polishing, a polishing liquid is supplied to the polishing surface of the semiconductor wafer 11 by a polishing liquid supply means (not shown). The polishing liquid is accumulated in the combing 6b provided on the upper surface of the base 1 and surrounding the turntable 7, and is led out. The polished semiconductor wafer 11 moves to the wafer delivery position by moving the chuck table 7a by the index rotation of the turntable 7, and then moves the transfer arm 2 of the wafer unloading section 9B.
It is carried out by 4B.

Next, the structure of the wafer cleaning section 10 will be described with reference to FIG. In FIG. 7 showing a cross section taken along the line BB in FIG. 2, an opening 35a is formed in the upper part of the box-shaped cleaning frame 35 by partially cutting out the front surface and two side surfaces.
Is provided. The opening 35a is provided in the semiconductor wafer 11
Is large enough to allow the wafer carry-out section 9B holding the same to enter and exit. An opening 35c for drainage and a bearing boss 3 having a shape projecting upward are provided on the bottom 35b of the cleaning frame 35.
5d is provided. A bearing 38 is fitted in the bearing boss 35d, and a rotation support portion 40 is coupled to an upper portion of a vertical shaft portion 39 supported by the bearing 38.

A plurality of suction holes 40a are provided on the horizontal upper surface of the rotation support portion 40, and the suction holes 40a
It communicates with the suction hole 39a provided in the inside. When the semiconductor wafer 11 is placed on the upper surface of the rotary support part 40, the suction control part 46 connected to the suction hole 39a is driven to perform vacuum suction from the suction hole 39a, so that the semiconductor wafer 11
Is sucked and held on the upper surface of the rotation support section 40.

A pulley 41 is connected to a lower portion of the shaft portion 39. A pulley 43 connected to a rotating shaft 44a of a motor 44 and a belt 42 are tuned to the pulley 41. The motor 44 is driven by a motor drive unit 45.
By driving the motor 44, the shaft 39 rotates, and therefore the semiconductor wafer 11 held by the rotation support 40 is rotated.
Spins.

A cylindrical cover portion 36 surrounding the semiconductor wafer 11 is vertically movably mounted inside the cleaning frame portion 35. A flange portion 36a provided above the cover portion 36 has a flange portion 36a. , The rod 37a of the cylinder 37 is connected. By driving the cylinder 37,
The cover 36 moves up and down. In a state where the cover 36 is raised, the flange 36 a is at a position in contact with the ceiling surface of the cleaning frame 35, and the opening 35 a is closed by the cover 36.

A cleaning liquid nozzle 47 and an air nozzle 49 are respectively provided on the ceiling surface of the cleaning frame 35 with the jetting direction directed downward. The cleaning liquid nozzle 47 is connected to a cleaning liquid supply unit 48 that supplies a cleaning liquid such as pure water. By driving the cleaning liquid supply unit 48, the cleaning liquid nozzle 47 is provided on the upper surface of the semiconductor wafer 11 supported by the rotation support unit 40 from the cleaning liquid nozzle 47. On the other hand, a cleaning liquid is sprayed.

At this time, by driving the motor 44, the semiconductor wafer 11 is in a spin rotation state, and the cleaning liquid jetted to the center of the semiconductor wafer 11 flows toward the outer edge of the semiconductor wafer 11 by centrifugal force. As a result, foreign matters adhering to the upper surface of the semiconductor wafer 11 are removed together with the cleaning liquid, and accumulate on the bottom surface of the cleaning frame 35. Then, the liquid is guided from the opening 35c to a wastewater treatment device (not shown) through the drainpipe 35e together with the cleaning liquid.

The air nozzle 49 is connected to an air supply unit 50.
When the air supply unit 50 is driven, air is jetted downward from the air hole 49 a of the air nozzle 49. Thereby, the semiconductor wafer 11 after cleaning
The cleaning droplets remaining on the upper surface are removed, and draining and drying are performed. The above operations are performed by the cylinder 37, the motor drive unit 45, the suction control unit 46, the cleaning liquid supply unit 48, and the air supply unit 50 by the control unit (not shown) of the apparatus main body.
It is performed by controlling by.

Next, the first and second plasma processing units 4A and 4B will be described with reference to FIG. These two plasma processing units have the same function, and only one or both of them are used depending on the work load. In FIG. 8 showing an AA cross section in FIG. 2, an opening 51a is provided on a side surface of the vacuum chamber 51.
The opening 51a is for carrying in and out the semiconductor wafer 11, and has a size that allows the wafer holding unit 17 holding the semiconductor wafer 11 to enter and exit. The opening 51a has a vertically movable gate 56, and the gate 56 is connected to a rod 57a of a cylinder 57. By driving the cylinder 57, the gate 56 moves up and down, and the opening 51a is opened and closed.

Openings 51b and 51c are provided on the ceiling surface and the bottom surface of the vacuum chamber 51, respectively. The upper electrode 5 is connected to the opening 51b via a vacuum-tight bearing 51e.
The second support portion 52a is inserted so as to be vertically movable. The support portion 52a is connected to the electrode lifting / lowering driving portion 55, and the upper electrode 52 is raised / lowered by driving the electrode lifting / lowering driving portion 55.

A gas outlet 52b is provided on the lower surface of the upper electrode 52.
Are opened, and the gas ejection port 52b is
Gas supply unit 54 through an inner hole 52c provided inside
Is connected to The gas supply unit 54 supplies a mixed gas mainly composed of oxygen and a fluorine-based gas such as CF ₄ for generating plasma.

A support portion 58a of the lower electrode 58 is inserted through an opening 51c on the bottom surface of the vacuum chamber 51 via an insulator 53 in a vacuum-tight manner. The upper surface of the lower electrode 58 is provided with a suction hole 5.
8b are provided, and the suction holes 58b are
a through the inner hole 58c provided inside the suction control unit 6
0 is connected. By driving the suction control unit 60 and performing vacuum suction through the suction holes 58 b, the semiconductor wafer 11 is suction-held on the upper surface of the lower electrode 58 and held. By driving the suction control unit 60 to apply a positive pressure to the suction holes 58b, the suction-held semiconductor wafer 11 is released from the suction state.

A cooling hole 58d is provided inside the lower electrode 58, and the cooling hole 58d is formed in the inner hole 5 in the support portion 58a.
8e, it is connected to the electrode cooling unit 61. By driving the electrode cooling unit 61 to circulate the coolant in the cooling holes 58d, the heat generated during the plasma processing is reduced by the lower electrode 5
8 to the refrigerant. Thereby, abnormal temperature rise of the lower electrode 58 is prevented, and damage to the protective film 11a of the semiconductor wafer 11 mounted on the lower electrode 58 due to heat can be prevented.

The vacuum chamber 51 is provided with an exhaust hole 51d, and the exhaust hole 51d is connected to a gas exhaust portion 59 via a pipe joint 51f. By driving the gas exhaust unit 59, the space in the vacuum chamber 51 is evacuated. The lower electrode 58 is electrically connected to the high-frequency power supply 62 via a support 58a. The upper electrode 52 is connected to the ground part 52d via the support part 52a, and by driving the high frequency power supply part 62, a high frequency voltage is applied between the opposed upper electrode 52 and lower electrode 58.

In the plasma processing, with the semiconductor wafer 11 placed and held on the lower electrode 58, the vacuum chamber 51 is first closed and the inside is evacuated. Then, the upper electrode 52 and the lower electrode 5 are supplied to the vacuum chamber 51 while the mixed gas for plasma generation is supplied from the gas supply unit 54.
8, a high frequency voltage is applied to the upper electrode 5
A plasma discharge occurs between the second electrode 58 and the lower electrode 58.
Due to the plasma etching effect generated by this,
The upper surface of the semiconductor wafer 11 is etched and thinned.

By controlling the gas supply unit 54, the electrode elevation drive unit 55, the gas exhaust unit 59, the suction control unit 60, the electrode cooling unit 61, and the high-frequency power supply unit 62 by a control unit (not shown) of the main unit, The above-described plasma processing operation is performed. At this time, data of the gas flow rate is transmitted from the gas supply unit 54, data of the chamber internal pressure is transmitted from the gas exhaust unit 59, and data of the refrigerant temperature (that is, the electrode temperature) is transmitted from the suction control unit 60 to the control unit. The control unit controls the plasma processing operation based on these data.

This semiconductor wafer processing apparatus is configured as described above. Hereinafter, the semiconductor wafer thinning processing will be described. This thinning is performed by forming a protective film 11 on a circuit forming surface of a semiconductor wafer 11 in which a plurality of semiconductor elements are formed.
This is performed after forming a. This semiconductor wafer 11
As shown in FIG. 3, the protective film 1 is formed on the magazine 2A (or 2B).
3A is supplied in a state where it is stored with the side 1a facing upward.
As shown in (2), the protective film 11a side is taken out by vacuum suction by the wafer holding unit 17. And the semiconductor wafer 1
The wafer holding unit 17 holding the wafer 1 by suction is moved to the pre-center unit 5 by the robot mechanism of the wafer transfer unit 3.

Here, the wafer holding unit 17 is rotated about an axis, and the semiconductor wafer 1 sucked and held by the wafer holding unit 17 is rotated.
1 is turned upside down. As a result, the semiconductor wafer 11 is suction-held on the upper surface of the wafer holding unit 17 with the protective film 11a facing downward as shown in FIG. By lowering the wafer holder 17, the semiconductor wafer 11 is mounted on the mounting table 20 with the protective film 11a side facing down. Thereafter, when the wafer holding unit 17 is retracted from the inside of the groove 21, the positioning claw 22a presses the outer peripheral portion of the semiconductor wafer 11 toward the center from three directions. Thereby, the alignment of the semiconductor wafer 11, that is, the pre-center operation is performed.

Next, the semiconductor wafer 11 positioned by the pre-center operation is picked up by the suction head 25A of the wafer loading section 9A and transferred to the polishing section 6 as shown in FIG. That is, the suction head 25A is moved to the wafer transfer position, where the semiconductor wafer 11 is transferred onto the chuck table 7a.

Thereafter, mechanical polishing by the polishing section 6 is performed. First, the chuck table 7a holding the semiconductor wafer 11 moves to the rough polishing station below the first polishing unit 8A, where the rough polishing using the grindstone 31A is performed. Next, the chuck table 7a moves to the finishing polishing station, and the second polishing unit 8B performs the final polishing using the finer grindstone 31B.
At this time, the semiconductor wafer 11 is thinned to a size thicker by a predetermined thickness than a predetermined target thickness, that is, a size larger by a dry etching allowance set in a range of 3 μm to 50 μm.

When the finish polishing is completed, the chuck table 7a holding the semiconductor wafer 11 moves to the wafer transfer station again due to the index rotation of the turntable 7. The semiconductor wafer 11 is picked up by the suction head 25B of the wafer unloading section 9B and moved to the wafer cleaning section 10 by rotating the transfer arm 24B. Therefore, the wafer unloading section 9B serves as a pre-cleaning transfer means for taking out the polished semiconductor wafer 11 from the polishing section 6 and passing it to the wafer cleaning section 10.

In the unloading operation of the semiconductor wafer 11, in the present embodiment, the protective film 11
Since a is formed, the bending strength is reinforced even in the state where the microcrack-introduced layer is generated by the mechanical polishing, and the semiconductor wafer 11 during transportation can be prevented from being damaged.

In FIG. 11, the control unit 69 includes a polishing unit 6, a wafer transfer unit 3 serving as a plate-like object transfer unit, a wafer transfer unit 9A, a wafer transfer unit 9B, a pre-center unit 5, a wafer cleaning unit 10, a micro crack unit. The first plasma processing apparatus 4A, the second plasma processing apparatus 4B, and the like, which are removal means, are controlled.

Next, the cleaning operation in the wafer cleaning section 10 will be described with reference to the flowchart of FIG. First, in FIG. 7, with the cover part 36 lowered, the wafer unloading part 9B
Is rotated, the semiconductor wafer 11 held by the suction head 25B is carried into the cleaning frame unit 35, and is transferred onto the rotary support unit 40 (ST1).

Next, the semiconductor wafer 11 is sucked and held by vacuum suction from the suction hole 40a of the rotary support portion 40 (ST2), and the suction of the semiconductor wafer 11 by the suction head 25B is released (ST3). Then, when the transfer arm 24B has retracted to the outside, the cover unit 36 is raised (ST4). As a result, the semiconductor wafer 11 is in a state in which the periphery is enclosed in the cleaning frame portion 35, and a state in which the cleaning liquid can be jetted.

After that, the motor 44 is driven to
0, and the semiconductor wafer 11 is spin-rotated (ST5). In this state, the cleaning liquid is jetted from the cleaning liquid nozzle 47 (ST6), and after a predetermined cleaning time has elapsed, the jetting of the cleaning liquid is stopped (ST7). Thereafter, air is blown from the air nozzle 49 (ST8), and the semiconductor wafer 1
1. Drain and dry the top surface. After a predetermined time, the air blowing is stopped (ST9).
Is stopped (ST10). Thus, the washing, draining and drying are completed.

When the rear cover 36 is lowered (ST11), the robot mechanism of the wafer transfer unit 3 is driven to move the wafer holder 17 into the cleaning frame 35 (ST12). Then, the suction hole 17 of the wafer holding unit 17
The upper surface of the semiconductor wafer 11 is sucked by a, and the suction by the suction hole 40a of the rotation support unit 40 is released (ST13). Then, the wafer holding unit 17 picking up the semiconductor wafer 11 is lifted and carried out of the cleaning frame unit 35 (ST14).

Next, the semiconductor wafer 11 from which foreign substances on the surface have been removed by washing is removed from the first plasma processing section 4A or the second plasma processing section 4A.
The plasma etching (dry etching) is performed here. In this plasma etching, the surface of the semiconductor wafer 11 thinned to a size larger by a dry etching allowance set in a range of 3 μm to 50 μm than a target thickness by mechanical polishing is further plasma etched to remove the dry etching allowance. Thereby, the semiconductor wafer 11 is thinned to the target thickness.

When finish polishing is performed with a grindstone of # 3000 to # 4000, the dry etching allowance is 5 μm to 6 μm.
It is desirable to set it to about m. As a result, the application rate of mechanical polishing with excellent polishing efficiency is increased as much as possible to improve the work efficiency, and the microcrack-introduced layer (generally 3 μm to 5 μm) generated by the finish polishing can be completely removed. And removal quality can be compatible.

This plasma etching will be described with reference to FIG.
This will be described with reference to FIG. As shown in FIG.
The wafer cleaning unit 10 is operated by the robot mechanism of the wafer transfer unit 3.
Then, the wafer holding unit 17 holding the semiconductor wafer 11 after cleaning on the lower surface by suction is moved to the side of the opening 51 a of the vacuum chamber 51. At this time, the gate 56 is lowered, the opening 51a is in an open state, and the upper electrode 52 is in a state of being raised by the electrode lifting drive unit 55. The wafer transfer unit 3 cleans the semiconductor wafer 1 after cleaning from the wafer cleaning unit 10.
1 is taken out and transferred to the plasma etching units 4A and 4B to serve as a conveying means after cleaning.

Next, as shown in FIG. 9B, the wafer holder 17 is moved into the vacuum chamber 51 through the opening 51a, and the wafer holder 17 is lowered.
The semiconductor wafer 11 held on the lower surface is placed on the upper surface of the lower electrode 58. Then, the suction by the wafer holding unit 17 is released, and the protective film 11 a of the semiconductor wafer 11 is sucked and held by the suction hole 58 b of the lower electrode 58.

Here, the semiconductor wafer 11 is mechanically polished by the polishing section 6, so that a microcrack-introduced layer is formed on the surface thereof, and the semiconductor wafer 11 is easily broken. Therefore, the semiconductor wafer 11 polished by the polishing unit 6 is picked up by the wafer unloading unit 9B and transferred to the wafer cleaning unit 10, or the wafer transfer unit 3 transfers the semiconductor wafer 11 from the wafer cleaning unit 10 to the plasma processing units 4A and 4B. The control means controls the speed so that the carrying-in speed is lower than the carrying speed by the wafer carrying unit 3 and the wafer carrying-out unit 9A before polishing (that is, before the generation of the microcrack introduction layer). The semiconductor wafer 11 thus polished is slowly handled and transported at a low speed to prevent cracks from microcracks.

Thereafter, if the wafer holding unit 17 is raised and retracted to the outside, the cylinder 57 is driven to raise the gate 56 and close the vacuum chamber 1 as shown in FIG. The upper electrode 52 is lowered by driving the electrode raising / lowering drive unit 55, and the distance between the lower surface of the upper electrode 52 and the upper surface of the lower electrode 58 is set to a predetermined value suitable for plasma etching as shown in FIG. The distance D between the electrodes is set.

Then, the above-described plasma etching process is performed in this state. That is, after the inside of the vacuum chamber 51 is evacuated, a mixed gas of a fluorine-based gas and an oxygen gas is ejected from the gas ejection port 52b on the lower surface of the upper electrode 52 as a plasma generating gas to maintain the inside of the vacuum chamber 51 at a predetermined gas pressure. I do. In this state, a high-frequency voltage is applied between the upper electrode 52 and the lower electrode 58. As a result, a plasma discharge is generated in the space between the upper electrode 52 and the lower electrode 58, and silicon on the surface of the semiconductor wafer is removed by the action of an active substance generated by the plasma discharge.

This plasma etching process is continuously performed until the semiconductor wafer 11 reaches the target thickness. Thereby, in the mechanical polishing process, the semiconductor wafer 1
The micro-crack-introduced layer formed on the surface of No. 1 is removed. This microcrack-introduced layer is usually 3 μm to 5 μm
As described above, the target thickness is mechanically polished to a dimension larger than the target thickness by a dry etching allowance exceeding the microcrack introduction layer, and then removed by plasma etching for the dry etch allowance. In the state where it has been processed, the microcrack-introduced layer is completely removed.

The semiconductor wafer 11 after the completion of the plasma etching is taken out by the wafer holding section 17 of the wafer transfer section 3 and stored in the same position of the magazine 2A (or 2B) in the wafer storage section 2 where the semiconductor wafer 11 is taken out. Is done. Then, the above operation is continuously repeated for the other semiconductor wafers 11. Since the microcrack-introduced layer is completely removed from the thinned semiconductor wafer 11 as described above, the bending strength of the semiconductor wafer 11 is improved and the semiconductor wafer 11 is not damaged. As described above, according to the present embodiment, it is possible to prevent breakage that occurs during a manufacturing process such as when the semiconductor wafer 11 is transported due to microcracks, and to improve the processing yield. Further, since the semiconductor wafer 11 after the removal of the microcrack-introduced layer is hard to be broken, the control means is configured to transport the semiconductor wafer 11 at a higher speed than before the removal of the microcrack-introduced layer and carry it out of the plasma processing units 4A and 4B. Controls the transfer speed of the wafer transfer unit 3, thereby improving work efficiency.

In addition, dry etching using plasma etching does not require a chemical solution such as hydrofluoric acid or nitric acid used in conventional wet etching, and thus generates harmful environmental pollutants such as nitrogen oxides. There is no need for waste liquid treatment of the used etching solution, and the environmental load can be greatly reduced.

Further, in the semiconductor wafer processing apparatus shown in the present embodiment, the regions of the polishing section 6 and the other sections are separately arranged on the common base section 1, and individual sections are provided between them. The semiconductor wafer 11 by the transfer means
Is passed. That is, the transfer and processing of the semiconductor wafer 11 in a state where the contaminants adhere to the work area (see the second half 1b shown in FIGS. 1 and 2) in which the adherence of contaminants such as polishing powder is inevitable using the polishing liquid. A clean room area such as a plasma etching process in which a high cleanliness is required for the object (the first half 1a shown in FIGS. 1 and 2)
The transfer of the semiconductor wafer 11 in the clean state in (see) is performed separately by separate transfer means.

As a result, the transfer means in the clean room area is not contaminated by the adhesion of the contaminants. Therefore, in the plasma etching process performed for the purpose of removing the microcrack-introduced layer, there is no adhesion of foreign matter that inhibits the etching effect on the surface of the semiconductor wafer 11, and the microcrack-introduced layer on the surface of the semiconductor wafer 11 is completely removed. Therefore, the bending strength can be improved. Further, the number of times of transfer for transferring the semiconductor wafer 11 during transfer can be suppressed to the minimum number as compared with the method of transferring the semiconductor wafer between a plurality of individual devices using a transfer means such as a robot. Therefore, the probability of breakage of the semiconductor wafer 11 during handling can be reduced, and the above-mentioned processing yield can be further improved.

The present invention is not limited to the above-described embodiment, but may be implemented with various changes. For example, in the present embodiment, mechanical polishing is performed in two stages of the rough polishing process and the finish polishing process, but the finish polishing process may be omitted. In this case, since the surface is polished with a coarse grindstone, the depth of the microcrack introduction layer on the upper surface of the wafer becomes 10 μm or more.

Therefore, when the dry etching allowance is left about 50 μm and the remaining is dry-etched and processed to a target thickness, the microcrack-introduced layer can be completely removed. By making the mechanical polishing only one step of the rough polishing step, the size of the polishing section can be reduced, and a semiconductor wafer processing apparatus with a small occupied floor area can be realized. The present invention can also be applied to processing of a quartz plate used for a quartz oscillator.

FIG. 13 is a sectional view of an etching portion of a semiconductor wafer processing apparatus according to another embodiment of the present invention. This etching unit differs from the wafer cleaning unit shown in FIG. 7 in that an etching solution supply unit 70 is added. The etchant supply unit 70 supplies the etchant to the nozzle 47 and discharges the etchant from the nozzle 47 onto the upper surface of the semiconductor wafer 11 to chemically etch and remove the microcrack introduction layer. That is, in this case, the nozzle 47 and the etching liquid supply unit 70 serve as micro crack removing means. The nozzle 47 of the present embodiment also serves as a cleaning liquid discharging nozzle and an etching liquid discharging nozzle.

The etching liquid is discharged from the nozzle 47 to the center of the semiconductor wafer 11. At this time, the semiconductor wafer 11 is in a spin rotation state by driving the motor 44, and the etching liquid injected to the center of the semiconductor wafer 11 is Flows toward the outer edge of the semiconductor wafer 11 due to centrifugal force. As a result, the entire upper surface of the semiconductor wafer 11 is uniformly etched, and the microcrack introduction layer is removed.

[0081]

According to the present invention, it is possible to perform a thinning treatment of a plate-like body such as a semiconductor wafer with a short work time and good workability while preventing the plate-like body from being cracked from microcracks.

[Brief description of the drawings]

FIG. 1 is a perspective view of a semiconductor wafer processing apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of a semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 3 is a perspective view of a wafer storage unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 4 is a perspective view of a wafer storage unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 5 is a partial plan view of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 6 is a side view of a polishing unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 7 is a sectional view of a wafer cleaning unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 8 is a sectional view of a plasma processing unit of the semiconductor wafer processing apparatus according to one embodiment of the present invention;

FIG. 9 is a process explanatory view of a semiconductor wafer processing method according to one embodiment of the present invention;

FIG. 10 is a process explanatory view of a method for processing a semiconductor wafer according to one embodiment of the present invention;

FIG. 11 is a block diagram of an apparatus for processing a semiconductor wafer according to an embodiment of the present invention;

FIG. 12 is a flowchart of semiconductor wafer cleaning in the semiconductor wafer processing method according to one embodiment of the present invention;

FIG. 13 is a sectional view of an etching unit of a semiconductor wafer processing apparatus according to another embodiment of the present invention.

[Explanation of symbols]

2 Wafer storage unit 3 Wafer transfer unit (first plate transfer unit, second plate transfer unit) 4A First plasma processing unit 4B Second plasma processing unit 5 Pre-center unit 6 Polishing unit 8A First Polishing unit 8B Second polishing unit 9A Wafer carry-in section 9B Wafer carry-out section 10 Wafer cleaning section 11 Semiconductor wafer 69 Control section 70 Etching liquid supply section

Claims (6)

[Claims] A mechanical polishing means for mechanically polishing a plate-like body;
Microcrack removing means for removing microcracks formed on the surface of the plate by mechanical polishing by etching, and a first plate which carries the plate polished by the mechanical polishing means into the microcrack removing means. Body transporting means, and a second plate-like body transporting means for carrying out the plate-like body from which the microcracks have been removed by the microcrack removing means from the microcrack removing means, the microcracks being removed by the microcrack removing means. An apparatus for thinning a plate-like body, wherein the conveying speed of the previous plate-like body is made slower than the conveying speed after the micro-cracks are removed by the micro-crack removing means. 2. The plate-shaped member according to claim 1, wherein the same plate-shaped member conveying means also serves as said first plate-shaped member conveying member and said second plate-shaped member conveying member. Body thinning device. 3. The apparatus according to claim 1, wherein said first plate-like body transporting means and said second plate-like body transporting means have a plate-like body holding portion for attracting and holding a plate-like body. 3. The apparatus for thinning a plate-like body according to 2. 4. The apparatus for thinning a plate-shaped body according to claim 3, further comprising a hand rotating mechanism for rotating said plate-shaped body holding portion to turn said plate-shaped body upside down. 5. A step of mechanically polishing a plate-like body by a mechanical polishing means, a step of carrying a mechanically polished plate-like body into a micro-crack removing means by a first plate-like body transporting means, and a step of removing microcracks. Removing the microcracks on the surface of the plate-like body by means, and carrying out the microcrack-removed plate-like bodies from the microcrack removing means by a second plate-like body transporting means; The transfer speed of the plate-like body is controlled such that the transfer speed of the plate-like body by the plate-like body transfer means is lower than the transfer speed of the plate-like body by the second plate-like body transfer means. Thinning method. 6. The plate-shaped member according to claim 5, wherein the same plate-shaped member conveying means also serves as said first plate-shaped member conveying member and said second plate-shaped member conveying member. How to thin the body.