JPH08267358A - Simultaneous mirror surface abrasive device of semiconductor substrate - Google Patents

Abstract

PURPOSE: To apply a mirror abrasion to all the units of one lot even in case where a wafer number of one lot fed out of the same monocrystal silicone ingot will not turn to a multiple of the sheet number of an abrasive unit. CONSTITUTION: Four units of mirror abrasive units 1A to 1D are installed side by side and each substrate is conveyed to each unit from a loader 30 of a semiconductor substrate, and this substrate is made detachably conveyable in an interval with a work surface plate 10 and thereby a lot of substrates are formed into being made simultaneously polishable. In addition, the number of substrate holding chucks 12 of the work surface plate 10 of one unit of the mirror abrasive unit 1D is made into such a unit as reduced to four pieces from the five pieces, and three units of 5-piece simultaneous abrasion and one unit of 4-piece simultaneous abrasion are combined together, through which all wafers can be polished so accurately under the same condition, no matter what the number of pieces may be.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for simultaneously polishing a plurality of wafers by providing a plurality of polishing units for holding a plurality of semiconductor substrates such as silicon wafers and polishing them for mirror-polishing. High-precision mirror polishing is possible, and even if the number of wafers in one lot cut out from the same single crystal silicon ingot is not a multiple of several leaves of the polishing unit, it is possible to perform mirror polishing for all lots at the same time. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous mirror surface polishing apparatus for semiconductor substrates, which prevents reduction in yield in the mirror surface polishing apparatus.

[0002]

2. Description of the Related Art At present, the most common mirror polishing of a semiconductor substrate made of silicon or the like is so-called single-side polishing in which only one side is polished. To explain a general mirror polishing apparatus, a polishing platen on which a plurality of semiconductor substrates are attached is pressed against a polishing cloth made of polyurethane resin or the like adhered to a rotary table with a predetermined pressure, and a particle size of about 5 to 300 nm, for example. the SiO ₂ abrasive grains with caustic soda, and about pH9~12 are suspended in an alkaline solution such as ammonia and ethanolamine, using a polishing solution comprising a so-called colloidal silica, it is relatively rotated, the machine according to the abrasive grains Polishing by a mechanochemical polishing method utilizing both the chemical action and the chemical action by etching of an alkaline solution.

There are various methods for fixing a semiconductor substrate to a polishing platen, and as a wax mounting method for sticking with the above wax or the like, Japanese Patent Laid-Open No. 1-210 is known.
No. 259, Japanese Unexamined Patent Publication No. 1-289657, etc., there are mirror polishing apparatuses, and as a waxless mount type adsorbing to a polishing platen, Japanese Patent Application Laid-Open Nos. 64-2858 and 64-45567. There is a mirror polishing device shown.

[0004]

The mirror surface polishing apparatus is required to remove not only high flatness but also micro scratches and haze to obtain a high quality polished surface free from processing distortion. Contrary to this, improvement of polishing efficiency is also required. In order to improve the polishing efficiency, a waxless mount that facilitates the work of attaching the wafer to the wafer surface plate and the cleaning after polishing is advantageous, but local etching or Wax mounts are currently the mainstream because of problems with quality such as stains.

The Applicant has previously conducted various studies on the optimization of the rotating action for the purpose of a mirror-polishing apparatus which is intended to improve the polishing efficiency, which is contrary to the improvement of the quality for obtaining a polished surface without processing distortion. , A plurality of suction chucks are rotatably mounted on a work surface plate arranged below, and the polishing cloth surface plate arranged above and the work surface plate are arranged so as to face each other with a slight eccentric rotation axis. The rotation of the work surface plate, the rotation of the suction chuck, the rotation of the polishing cloth surface plate, and the eccentricity of the rotating shafts of the upper and lower surface plates are caused by the semiconductor substrate vacuum-adsorbed on the upper surface of the suction chuck.
It has been found that polishing can be performed by applying two rotating actions, and an extremely high quality polishing surface can be obtained while improving the polishing efficiency, and a high performance and high efficiency mirror polishing device is proposed (Japanese Patent Application No. 5-259283). No.)

On the other hand, the number of wafers in one lot put into mirror polishing is an inconstant depending on the length of the single crystal and the yield of the pre-polishing process. In order to perform mirror polishing of all the wafers in the same lot under substantially the same conditions and with good yield, it is necessary to have an apparatus capable of setting the same polishing conditions and simultaneously and continuously polishing a large number of wafers. However, in the conventional system for polishing using a plurality of apparatuses capable of simultaneously polishing a plurality of wafers, only a multiple of the number of wafers accommodated in each polishing apparatus can be polished, and when the number of wafers in one lot is different from the multiple, Fractions cannot be polished. For example, even if two or three wafers having a fractional number are polished in an apparatus that mounts and polishes five wafers, the wafer quality is deteriorated and treated as a defect, resulting in a decrease in yield. It will be.

The present invention, in a mirror polishing apparatus for a semiconductor substrate which is polished by the mechanochemical polishing method, uses a mirror polishing apparatus capable of extremely highly precise mirror polishing, and improves polishing efficiency by simultaneous polishing. Provide a simultaneous mirror surface polishing apparatus for semiconductor substrates capable of performing mirror polishing for all lots in one lot even if the number of wafers in one lot cut out from the same single crystal silicon ingot does not become a multiple of the number of polishing units accommodated. Has an aim.

[0008]

In order to improve the polishing efficiency by simultaneous polishing, the inventors of the present invention used the same structure as the previously proposed high-performance and high-efficiency mirror-polishing apparatus. As a result of various studies for the purpose of operating under polishing conditions and for a configuration capable of performing high-performance and high-efficiency mirror polishing on all units in the same lot, a plurality of such mirror-polishing units are provided side by side to load semiconductor substrate loaders. The substrate is transferred to each unit and can be transferred to and from the work surface plate so that a large number of substrates can be polished at the same time. Further, one work of a plurality of mirror surface polishing units is used. By using a unit in which the number of substrate holding chucks on the platen is reduced from 5 to 4, for example,
A combination of multiple simultaneous polishing of five wafers and one simultaneous polishing of four wafers should be used to polish all wafers with high precision under the same conditions for any number of wafers in one lot (12 or more). They found out and completed this invention.

That is, according to the present invention, a polishing cloth surface plate having a polishing cloth adhered to the surface thereof and a work surface plate having a plurality (N sheets) of substrate holding chucks for suction fixing or accommodating and supporting are rotatably mounted. And a structure in which the rotation axis of the surface plate is eccentric so as to be opposed to each other, and a supply means for supplying a polishing liquid in which abrasive grains are suspended in a solution to the surface of the semiconductor substrate held on the substrate holding chuck, and A plurality of (M) mirror-like polishing units having rotation driving means for bringing the polishing cloth into contact with the semiconductor substrate by the pressure means to relatively rotate the upper and lower surface plate and the substrate holding chuck are provided side by side. A loader and a conveyor belt that conveys the substrate to each unit, and a handling device that makes it possible to convey the substrate between the conveyor belt and the work surface plate are attached to polish a large number of substrates at the same time. Polishing unit A simultaneous mirror polishing apparatus for semiconductor substrate, wherein the substrate holding chuck number of one work plate out of a N-1 sheets.

In the present invention, either the work surface plate or the polishing cloth surface plate may be an upper surface plate or a lower surface plate, and the substrate holding chuck may be either a suction type or a template type, and the number of chucks is arbitrary. However, 3 or more is preferable. The work surface plate has a structure in which a plurality of suction chucks are rotatably placed on the upper surface of the work surface plate and is rotated. As in the embodiment, the work surface plate serving as the lower surface plate is rotatably supported by the suction chucks. In addition to adopting a rotation drive means that interlocks with the rotation of the work surface plate by engaging the sun gear provided on the rotation shaft of the surface plate with the drive shaft penetrating downward and engaging the planetary gear at the end of the drive shaft, Various drive methods such as known gear drive can be appropriately selected such that the rotation is controlled separately from the work surface plate.

A suction-type substrate holding chuck (hereinafter referred to as a suction chuck) is for vacuum-sucking and fixing a semiconductor substrate. The shape and material of the suction plate provided on the chuck upper surface are not particularly limited, but known acrylic materials and ceramics. It is possible to apply a configuration in which a groove or hole is appropriately formed by using a material or the like. Further, a decompression pump or the like can be used as the suction means, but since the suction chuck and the work surface plate rotate, it is necessary to arrange a rotary joint or the like in a pipe or the like connected to the pump. The suction force of the suction chuck that has been subjected to the groove or hole processing can be processed with high accuracy by controlling the vacuum pressure to be -250 to -650 mmHg. That is, if the suction force is less than -250 mmHg, the semiconductor substrate is likely to fly or crack, and if it exceeds -650 mmHg, minute waviness or the like occurs on the substrate and a highly accurate mirror surface cannot be obtained.

In the present invention, the polishing cloth surface plate has a structure in which a predetermined polishing cloth is adhered to the lower surface of the polishing cloth so that the polishing cloth is brought into contact with the semiconductor substrate on the suction chuck or is lifted and lowered to a predetermined position when the substrate is attached and detached. If so, the lifting mechanism can employ any of the known structures in addition to the lever type of the embodiment. As the rotation driving means, known gear driving can be adopted in addition to the belt driving of the embodiment. The mirror polishing unit of the present invention is characterized in that the rotating shafts of the upper and lower surface plates are eccentrically opposed to each other, and fixed shafts are arranged so that the amount of eccentricity is constant, and a polishing cloth to be an upper surface plate as shown in the embodiment. By holding the surface plate so that it can move in the horizontal direction, the polishing cloth surface plate can be eccentrically arranged with respect to the work surface plate, and by further moving the polishing cloth surface plate by the radius of the work surface plate, for example, the suction chuck It is possible to adopt a configuration that facilitates pull-out inspection and the like. When the polishing cloth surface plate is brought into contact with the semiconductor substrate on the substrate holding chuck to perform polishing, the pressure is set to a predetermined pressure. As used, it is appropriately selected according to the support and lifting mechanism of the polishing cloth surface plate adopted, and the pressing force is selected according to the type of polishing cloth and polishing liquid.

In the present invention, any known polishing suspension such as colloidal silica can be applied to the polishing liquid, and the capacity of the discharge pump can be changed depending on the shape and position of the polishing liquid nozzle, the concentration and supply amount of the polishing liquid, and the like. Is selected. Further, in order to prevent the liquid from falling by receiving the polishing liquid supplied from the nozzle provided at the center of the polishing cloth surface plate, by disposing the polishing liquid receiving plate between each suction chuck of the work surface plate, The polishing liquid flows from the center of the surface plate to the outer peripheral side between the polishing cloth and the polishing liquid receiving plate, and the polishing liquid can be supplied to the entire surface of the polishing cloth without dropping downward.

[0014]

The operation of the simultaneous mirror polishing apparatus for semiconductor substrates according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a front explanatory view showing the structure of a mirror polishing unit according to the present invention. FIG. 2 is a top view showing the structure of the handling device according to the present invention. FIG. 3 is an explanatory top view showing a configuration in which three mirror polishing units are provided side by side. FIG. 4 is an explanatory top view showing a structure in which four mirror polishing units according to the present invention are provided together. The surface plate surface of the work surface plate 10 in which the rotary shaft 11 is erected vertically in the base (not shown) of the mirror polishing unit 1 is exposed on the base, and the scatter preventing cover 2 of the polishing liquid is provided around the surface. A polishing liquid recovery tray 3 is provided between the outer periphery of the work surface plate 10 and the scattering prevention cover 2.

A drive gear (not shown) is provided below the rotary shaft 11 of the work surface plate 10, and meshes with a gear of a reduction gear of a motor. Further, a sun gear is provided above the rotary shaft 11. ing. Further, on the work surface plate 10, five suction chucks 12 are arranged at equal intervals and are rotatably supported, and the rotation shaft thereof penetrates the work surface plate 10 and the planetary gear provided at the tip is the above-mentioned sun gear. It meshes with the gear. A suction pipe connected to the suction chuck 12 is provided in the work surface plate 10, and is connected to an external decompression pump via a rotary joint in the rotary shaft 11. The suction plate of the suction chuck 12 is an acrylic plate provided with a large number of circumferential grooves.

Polishing cloth surface plate 20 facing the work surface plate 10
The rotary shaft 21 is rotatably held by a bearing on a surface plate support, and the surface plate support is horizontally movably mounted on slide rails on horizontal bases arranged on both sides of the base via sliders. The eccentric amount of the rotation center of the polishing pad surface plate 20 with respect to the rotation center of the work surface plate 10 can be arbitrarily set by the horizontal holding mechanism of the surface plate support table, but a lock (not shown) is set so as to be a preset eccentric amount. It is configured to be positioned by a mechanism. Further, by making the polishing cloth surface plate 20 movable about the radius of the work surface plate 10 by the horizontal holding mechanism, the suction chuck 12 can be pulled out and inspected.

A balancer mechanism for suspending the polishing cloth surface plate 20 to set a predetermined pressure is not shown, but is a rotary shaft 21.
The upper end of the balancer arm is placed in the surface plate support, and is supported by one end of a balancer arm that is slidably supported by a bearing.
The other end of the lever is connected to a high pressure cylinder for raising and lowering and a piston rod of a low pressure cylinder for pressurizing. Further, the abrasive is pumped from a tank (not shown) by a pump and enters from the upper end of the pipe penetratingly arranged in the rotary shaft 21 of the polishing cloth surface plate 20, and faces the work surface plate 10 from the central portion of the polishing cloth surface plate 20. It is ejected from the nozzles arranged in the outer peripheral direction, or is ejected in the inner peripheral direction from the nozzles 4 arranged on the outer peripheral side of the work surface plate 10 as shown.

As shown in FIG. 4, the mirror polishing unit 1 has a belt conveyor 13 arranged in the width direction on the base of the unit 1.
Are arranged in parallel in the conveying direction of the unit, and a silicon wafer loader 30 is arranged at one end of the unit group, the left end of the figure, and the silicon wafer 5 placed on the belt conveyor 13a is placed on the unit 1 base. The silicon wafer 5 is conveyed by a belt conveyor 13b or the like arranged and stopped at a predetermined position, raised and lowered by a mounting table (not shown) and centered by a pair of centering arms 14 and 14, and the silicon wafer 5 is held by a suction plate at the tip of the handler arm 15. It is adsorbed, and the arm 15 is rotated to be transferred onto the suction chuck 12 of the work surface plate 10. At this time, the polishing cloth surface plate 20 of the mirror surface polishing unit 1 is raised by the high pressure cylinder, and the work surface plate 10 is rotationally indexed and controlled so as to stop at a predetermined position below the tip of the handler arm 15 about which the suction chuck 12 has swung. ing.

As shown in FIG. 4, when four mirror surface polishing units 1A to 1D are arranged in parallel, the silicon wafers delivered from the loader 30 are sequentially allocated and the required mirror surface polishing is performed using the belt conveyors 13b to 13e. It is sent to the units 1A to 1D and the suction chuck 1 as shown in FIG.
Placed one after another on 2. When the silicon wafer 5 is placed on each suction chuck 12 of the work surface plate 10 and the suction is completed, the polishing cloth surface plate 20 descends by the high pressure cylinder and contacts the silicon wafer 5, and a predetermined pressure is applied by the low pressure cylinder. After that, the abrasive is sprayed from the nozzle, the polishing cloth surface plate 20 and the work surface plate 10 are rotationally driven, and the suction chuck 12 is also interlocked with each other. And polishing is started with these relative rotational movements.

A plurality of suction chucks 12 are attached to the work surface plate 10.
Rotatably mounted, polishing cloth surface plate 20 and the work surface plate 1
Since 0 and 0 are arranged so as to face each other with the rotation axis slightly decentered, the work wafer surface plate 10 is revolved, the suction chuck is rotated, and the polishing cloth surface plate 20 is rotated on the silicon wafer 5 vacuum-adsorbed on the upper surface of the suction chuck 12. The mechanochemical polishing can be performed by applying the four rotational actions of the eccentricity of the rotating shaft of the upper and lower surface plates to obtain a polishing surface with no processing distortion and an extremely high quality polishing surface while improving the polishing efficiency. To be

When the predetermined polishing is completed, the polishing liquid is supplied,
The rotation of the work surface plate 10 and the polishing cloth surface plate 20 is stopped, and the polishing cloth surface plate 20 is raised by the high-pressure cylinder. Contrary to the above, the handler arm 15 is mounted on the suction chuck 12 which is rotationally indexed to a predetermined position. After the silicon wafer 5 is swiveled and sucked, the silicon wafer 5 is sucked and then transferred to the mounting table, and then, is conveyed by the belt conveyors 13b to 13e and transferred to a required next step.

Here, when three mirror polishing units 1A to 1C are arranged in parallel as shown in FIG.
The number of silicon wafers carried out from 0 becomes one set of five, which is carried into each unit, polished, and then automatically carried to the next step, but the number of wafers in one lot in the loader 30 was not a multiple of five. At that time, a fraction of that cannot be polished and is treated as a defective product, resulting in a reduced yield. However, as shown in FIG. 4, four mirror polishing units 1A to 1D are arranged in parallel, and when one of the mirror polishing units 1D has four suction chucks 12 on the work surface plate 10, three mirror polishing units 1A to 1D are arranged. A combination of five mirror polishing units 1A to 1C capable of simultaneously polishing and one mirror polishing unit 1D capable of simultaneously polishing four wafers is used, and all wafers can be processed for any number of wafers in one lot of 12 or more. Highly accurate polishing can be performed under the same conditions.

[0023]

EXAMPLE A simultaneous mirror-polishing apparatus according to the present invention comprising a combination of three mirror-polishing units 1A to 1C capable of simultaneously polishing five sheets and one mirror-polishing unit 1D capable of simultaneously polishing four sheets as shown in FIG. Simultaneous mirror polishing was performed on about 100 wafers in one lot. As shown in Table 1, the number of 5 wafers and the number of 4 wafers simultaneously polished are the same in all cases. I was able to.

[0024]

[Table 1]

[0025]

The simultaneous mirror polishing apparatus for semiconductor substrates according to the present invention has a plurality of high-performance and high-efficiency mirror polishing units provided side by side to convey the substrates from the semiconductor substrate loader to each unit, and to carry the substrates onto the work surface plate. The configuration is such that a large number of substrates can be polished at the same time by being detachable and transportable between them, and further, the number of substrate holding chucks of one work surface plate of a plurality of mirror surface polishing units is as shown in the embodiment, By reducing the number of wafers from five to four, a combination of multiple 5 wafers simultaneous polishing and one 4 wafers simultaneous polishing can be used for any number of wafers in one lot (12 wafers or more). All wafers can be polished with high precision under the same conditions.

[Brief description of drawings]

FIG. 1 is a front explanatory view showing a configuration of a mirror polishing unit according to the present invention.

FIG. 2 is an explanatory top view showing a configuration of a handling device according to the present invention.

FIG. 3 is an explanatory top view showing a configuration in which three mirror polishing units are provided side by side.

FIG. 4 is an explanatory top view showing a configuration in which four mirror polishing units according to the present invention are provided side by side.

[Explanation of symbols]

 1, 1A to 1D Mirror polishing unit 2 Scattering prevention cover 3 Polishing liquid recovery dish 4 Nozzle 5 Silicon wafer 10 Work surface plate 11 Rotating shaft 12 Suction chuck 13 Belt conveyor 14 Centering arm 15 Handler arm 20 Polishing cloth surface plate 21 Rotating shaft 30 Loader

Claims (1)

[Claims] 1. A polishing cloth surface plate having a polishing cloth adhered to the surface thereof and a work surface plate having a plurality of (N sheets) substrate holding chucks rotatably mounted thereon, which are fixed by suction or accommodated for storage, are vertically opposed to each other. And has a configuration in which the rotation axis of the surface plate is eccentric,
Supplying means for supplying a polishing liquid in which abrasive grains are suspended in a solution to the surface of the semiconductor substrate held on a substrate holding chuck, and a polishing cloth is brought into contact with the semiconductor substrate by a pressing means to hold the upper and lower platens and the substrate. A plurality of mirror surface polishing units (M units) having rotation driving means for enabling relative rotation of the chuck are provided side by side, and a semiconductor substrate loader, a conveyor belt for conveying the substrate to each unit, and a conveyor belt and a workpiece fixing unit. It has a structure for simultaneously polishing a large number of substrates by attaching a handling device capable of being conveyed to and from the plate, and one of the M mirror polishing units has a substrate holding chuck number N-1.
Simultaneous mirror polishing apparatus for semiconductor substrates, characterized in that it is a single piece.