JPH03173129A - Polishing apparatus - Google Patents

Abstract

PURPOSE:To suppress a lack of uniformity in supporting rigidity, caused by a back pad and to prevent flatness from being deteriorated by a method wherein, in a polishing apparatus of a waxless type, an object to be polished as a plate body is vacuum-sucked and held directly to a suction face of a polishing plate. CONSTITUTION:It is structured that a plurality of vacuum-pressurization holes 5a connected to a suction face of a wafer 1 are formed in a polishing plate and that the back side of the wafer 1 is sucked and fixed so as to be freely detachable. An O-ring 7 is attached to a mounting groove 5b in an outer circumference position of the wafer 1 in order to prevent an abrasive 8 from creeping between the wafer 1 and the polishing plate 5. The polishing plate 5 is separated from a polishing surface plate 3; the wafer 1 is mounted on each mounting hole 12a of a template 12. An internal pressure of the vacuum and pressurization holes 5a in the polishing plate 5 is set to a negative pressure; the back of the wafer 1 is sucked and fixed stably. In succession, the wafer is lowered toward the polishing surface plate 3; the wafer 1 is pressed at a prescribed pressure. While the abrasive 8 is being supplied, a polishing cloth 4 pasted on the polishing surface plate 3 being turned is slid to execute a polishing treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polishing apparatus, and in particular, to a polishing apparatus for polishing a semiconductor wafer (hereinafter referred to as a wafer) in semiconductor manufacturing technology. The present invention relates to a technique that is effective when applied to a waxless type polishing apparatus, which is capable of preventing deterioration of flatness caused by polishing agents and preventing corrosion of the back surface of a wafer due to polishing agents.

[Prior Art] In the polishing process of wafers in semiconductor manufacturing technology, high precision and defect-free surfaces are required, for example, with the miniaturization of devices and the development of MO3 structure devices.

In addition, the polishing mechanism is a mechano-chemical polishing method that combines mechanical elements such as colloidal silica and etching elements using alkali.
Since the properties of the polishing agent and polishing cloth are the main factors determining the wafer surface condition, many improvements have been made, but polishing equipment has become increasingly important in recent years to meet demands for improved wafer precision, especially flatness. ing.

Furthermore, the polishing process can be roughly divided into two stages called lapping process and polishing process. In the lapping process, both sides of the sliced wafer are flattened, and the thickness variation across the wafer is also smoothed. is corrected.

On the other hand, in the polishing process, after the lapping process is completed, several stages of polishing steps are repeated using a polishing cloth called a polishing cloth, and the surface of the wafer is made into a mirror-like state with a predetermined precision.

As one type of polishing equipment that performs such polishing processing, for example, Kogyo Choshukai Co., Ltd., published November 20, 1985, "Electronic Materials Special Edition, VLSI Manufacturing Test Equipment Guidebook", November 1985 issue. Separate volume P41-P
There is a waxless polishing device described in documents such as No. 49.

That is, in the above-mentioned waxless polishing apparatus, a template in which a plurality of mounting holes slightly larger than the outer diameter of the wafer are formed is placed on a polishing plate provided opposite to a polishing surface plate covered with a polishing cloth. A back pad is fixed to the polishing plate and has a porous layer in each mounting hole. After the wafer is suctioned and fixed to the back pad, a certain amount of pressure is applied to the wafer between the polishing plate and the polishing surface plate while supplying abrasive to the polishing cloth, and the polishing plate and the polishing surface plate are placed on the opposite surface of the wafer. The mechanism is such that the polishing surface of the wafer is slid on the polishing cloth by relatively displacing the polishing cloth, thereby performing the polishing process.

[C] Problem to be solved by the invention [H] However, in the above-mentioned conventional technology, since the wafer is attached via the back pad, absorption of abrasive by the back pad and hardness of the back pad during polishing are difficult. However, this method does not take into account the possibility of abrasive changes and the intrusion of abrasives into the wafer suction surface, resulting in deterioration of the back pad and changes in physical properties.

For example, the causes of deterioration of wafer flatness include:
The outer periphery of the back pad comes into contact with alkaline abrasives,
Alternatively, the elasticity and hardness of the wafer change due to intrusion into the back pad, and the supporting rigidity of the wafer becomes non-uniform over the entire surface of the back pad.

Therefore, there is a problem in that it cannot meet the recent demands for wafer precision, especially improvement in flatness, due to deterioration in wafer flatness and surface roughness due to wafer surface corrosion.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a polishing apparatus that can obtain highly accurate flatness of an object to be polished.

Another object of the present invention is to provide a polishing apparatus that can prevent surface roughening of the back surface of an object to be polished due to secondary corrosion caused by the polishing agent.

Furthermore, another object of the present invention is to obtain a polishing apparatus that can automate the attachment and detachment of objects to be polished to and from a polishing plate.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for Solving the Problems] Among the inventions disclosed in this application, a brief overview of typical inventions is as follows.

That is, the polishing apparatus of the present invention includes a polishing cloth for polishing a plate-like object to be polished, a polishing plate for holding the object to be polished, and a polishing load loading mechanism for applying a predetermined pressure to the polishing plate. This is a waxless type polishing apparatus in which the object to be polished is directly held by vacuum suction on the suction surface of the polishing plate.

Further, the polishing plate is made of a porous material, and the adsorption force to the object to be polished is
It is designed to act uniformly on the entire surface of the object to be polished.

Furthermore, the vacuum/pressure holes of the polishing plate are formed in a grid, slit shape, or porous shape to reduce the contact area with the object to be polished.

Further, the forward rotating polishing plate has a sealing member disposed at a position on the outer periphery of the object to be polished on the adsorption surface of the object to be polished, and the sealing member prevents abrasive from entering between the object to be polished and the polishing plate. This is to prevent this.

Further, the object to be polished can be attached and detached by setting the internal pressure of the vacuum/pressure hole of the polishing plate to negative pressure or positive pressure.

[Function] According to the above-described polishing apparatus, by holding the object to be polished by vacuum suction directly on the suction surface of the polishing plate, the object to be polished is directly attached to the rigid surface of the polishing plate without using a pack pad as in the past. The object to be polished can be vacuum-adsorbed and the supporting rigidity of the object to be polished can be stabilized at all times.

Furthermore, by forming the polishing plate from a porous material, the vacuum adsorption force of the object to be polished can be applied uniformly to the entire surface of the object to be polished, thereby improving the adsorption force of the object to be polished.

Furthermore, by forming the vacuum/pressure holes of the polishing plate into a lattice, slit shape, or porous shape, the contact area with the object to be polished is reduced, and the influence of foreign matter adhering to the polishing plate suction surface is reduced. can do.

Further, in the polishing plate, by disposing a sealing member at the outer circumference of the object to be polished on the object suction surface,
It is possible to prevent the abrasive from entering between the object to be polished and the polishing plate, and to suppress corrosion on the back surface of the object to be polished.

Furthermore, by setting the internal pressure of the vacuum/pressure hole of the polishing plate to negative pressure or positive pressure, it is possible to automate the attachment and detachment of the object to be polished.

[Example] Fig. 1 is an enlarged sectional view of a main part showing a polishing plate of a polishing apparatus which is an embodiment of the present invention, and Figs. 2 to 5 are main parts showing modifications of the polishing plate of this embodiment. 6 is a plan view showing the suction surface of the polishing plate in FIG. 5, FIG. 7 is a front view schematically showing the polishing device of this embodiment, and FIG. 8 is a diagram of the polishing device of this embodiment. FIG. 3 is a plan view showing a polishing plate.

First, the configuration of the polishing apparatus of this embodiment will be explained with reference to FIG.

The polishing apparatus of this embodiment is a waxless type polishing apparatus 2 for a wafer (object to be polished) 1 used in a semiconductor manufacturing process, for example, and includes a polishing surface plate 3 arranged horizontally and a polishing cloth 4 for polishing the wafer 1. , a polishing plate 5 that holds the wafer 1, and a pressure cylinder (polishing load applying mechanism) 6 that presses the polishing plate 5 with a predetermined pressure. The polishing process is performed by rotation of the polishing surface plate 3.

The polishing surface plate 3 is configured to be rotated at a predetermined speed by a drive source such as a motor (not shown) via a drive shaft 3a provided at the center of the lower surface.

The wafer 1 is obtained by slicing a rod-shaped ingot made of silicon (Si) single crystal in the cross-sectional direction, and as shown in FIG. An orientation flat la is formed.

The polishing cloth 4 is attached to the upper surface of the polishing surface plate 3, that is, the surface facing the polishing plate 5, and polishes the wafer 1 when the polishing surface plate 3 is driven.

As shown in FIG. 1, the polishing plate 5 has a plurality of vacuum/pressure holes 5a that communicate with the suction surface of the wafer l, and has a structure in which the back side of the wafer l is removably suctioned and fixed. There is. Further, a mounting groove 5b in which an O-ring (sealing member) 7 is mounted is formed at the outer circumferential position of the wafer 1, and the O-ring 7 prevents the abrasive 8 from entering into the gap between the evaporator 1 and the polishing plate 5. It has a structure that allows

Further, a driven shaft 9 is connected to the polishing plate 5 on its rear side, and this driven shaft 9 is supported by a casing (not shown) via a bearing 10 and a torquer arm 11 that is movable up and down. A vacuum/pressure hole 9a is provided inside the driven shaft 9.
is formed, and this vacuum/pressure hole 9a is connected to a fluid pressure source (not shown). A pressure cylinder 6 is connected to the upper end of the driven shaft 9 to apply a thrust force to the driven shaft 9 in the axial direction, and controls the vertical movement of the polishing plate 5 and moves the polishing plate 5 onto the polishing surface plate with a predetermined pressure. It has a structure that presses on the 3rd side.

Furthermore, a circular template 12 is attached to the surface of the polishing plate 50, that is, the surface facing the polishing surface plate 3. In this template 12, for example, as shown in FIG. 8, five mounting holes 12a are formed at positions equally dividing the circumferential direction so as to surround the driven shaft 9, and the wafer 1 is inserted into each of these mounting holes 12a. It has a structure that allows it to be installed.

The pressure cylinder 6 applies a predetermined pressing force to the polishing plate 5, and applies a pressure of, for example, 100 to 250 g/cm2 to each wafer l mounted in the mounting hole 12a of the polishing plate 12.
This applies a certain amount of pressure. Then, the polishing agent 8 is supplied from a nozzle (not shown) arranged in the center of the polishing surface plate 3.
The structure is such that the surface of the wafer 1 is polished while being supplied and dispersed outside the polishing cloth 4 by the centrifugal force generated by the rotation of the polishing surface plate 3.

Next, the operation of this embodiment will be explained.

First, with the polishing plate 5 separated from the polishing surface plate 3, the wafers 1 are mounted in the respective mounting holes 12a of the template 12 fixed to the polishing plate 5.

Then, by driving a fluid pressure source (not shown), the internal pressure of the vacuum/pressure hole 5a of the polishing plate 5 is set to a negative pressure, that is, a vacuum state, and the back surface of the wafer 1 is attracted to the suction surface of the polishing plate 5 to stabilize it. Fixed to.

Next, by operating the pressure cylinder 6, the polishing plate 5 is lowered toward the polishing surface plate 3, and the wafer 1 is pressed with a predetermined pressure between the polishing plate 5 and the polishing surface plate 3, and is stably pressed. A polishing cloth 4 placed on a rotating polishing surface plate 3 is slid on the attracted wafer 1 to perform a polishing process.

In this case, by continuing the polishing process for a predetermined time while supplying the polishing agent 8, the surface of the wafer 1 in contact with the polishing cloth 4 can be polished to a mirror-like state.

Furthermore, after the polishing process of the mounted wafer 1 is completed, the polishing plate 5 is raised by the reverse process to the above, that is, the pressure cylinder 6 is operated, and the polishing plate 5 is vacuumed by driving the fluid pressure source. Pressure hole 5
The internal pressure of a is set to a positive pressure state, and the suction of the wafer 1 is released.

Then, from the mounting hole 12a of the template 12, the sea urchin/"
After taking out the wafer, the polisher separates the plate 5 from the polishing surface plate 3, replaces it with a new wafer 1, and performs the polishing process again.

As described above, in the polishing apparatus 2 which is the polishing apparatus of this embodiment, a plurality of vacuum/pressure holes 5a are formed in the polishing plate 5, and the vacuum/pressure holes 5a are connected to the fluid pressure source (
By connecting the wafer 1 (not shown) to the suction surface of the polishing plate 5, there is no need to use a back pad that absorbs the abrasive 8 during polishing and changes its hardness as in the conventional case. The supporting rigidity of the wafer 1 can be stabilized at all times by directly vacuum suctioning the wafer. In this case, by forming a plurality of vacuum/pressure holes 5a in the polishing plate 5 as shown in FIGS. 1 and 2, the vacuum suction force of the wafer 1 is applied uniformly to the entire surface of the wafer 1. can be done.

As for the polishing plate 5, as shown in FIGS. 3 and 4, by fixing a porous suction plate (porous material) 13 made of, for example, alumina-based abrasive grains to the suction surface, the above-mentioned method can be achieved. Similarly, since the vacuum suction force of the wafer 1 can be applied uniformly to the entire surface of the wafer 1, it is possible to improve the flatness accuracy.

In addition, as shown in FIGS. 1 and 2, an O-ring 7, which is a sealing member, is provided at the outer circumference of the wafer 1 on the suction surface of the wafer 1, and as shown in FIG. Later, by applying a sealant (sealing member) 14 to the outer circumferential position of the wafer 1, and further arranging an edge sealing material (sealing member) 15 to the outer circumferential position of the wafer 1 as shown in FIGS. 4 and 5. , it is possible to prevent the abrasive 8 from entering between the wafer 1 and the polishing plate 5.

Further, conical grooves 5C having a bottom diameter of 0.1 to 1Q mm are formed in the suction surface of the polishing plate 5 in a lattice shape with an interval of 0.1 to 10 mm, as shown in FIGS. 5 and 6, for example. In this case, the suction surface does not come into contact with the entire surface of the wafer 1, and the supporting area of the wafer 1 is reduced, so that the influence of foreign matter adhering to the suction surface of the polishing plate 5 can be reduced.

In addition, in any of the above cases, when the wafer 1 is attracted, the vacuum
By setting the internal pressure of the pressurizing hole 5a to a negative pressure state and setting the pressure to a positive pressure state when removing the wafer 1, the wafer 1 can be easily mounted and removed.

As above, the invention made by the present inventor has been specifically explained based on Examples, but it should be noted that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Not even.

For example, the polishing plate 5 in the polishing apparatus of this embodiment
The shapes and structures are not limited to the vacuum/pressure holes 5a and the lattice-like conical grooves 5c as shown in FIGS. 1 to 6, and various other shapes such as slit grooves can be used. It is also applicable to the polishing plate 5 of.

In the above description, the invention made by the present inventor is mainly applied to a waxless type polishing apparatus used in a wafer polishing process in semiconductor manufacturing technology, which is the field of application of the invention, but the present invention is not limited to this. However, the present invention is not limited to polishing devices, and can be widely applied to other polishing devices such as magnetic disks in hard disk drives or quartz glass in photomask manufacturing.

[Effects of the Invention] Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly explained below.

(1) Waxless type, which is equipped with a polishing cloth for polishing a plate-like object to be polished, a polishing plate for holding this object to be polished, and a polishing load loading mechanism for pressurizing this polishing plate with a predetermined pressure. In the polishing device, the work to be polished, which is a plate surface body, is held by vacuum suction directly on the suction surface of the polishing plate, without using a pack pad as in the conventional case.
The object to be polished is vacuum-adsorbed directly onto the rigid surface of the polishing plate, and the support rigidity of the object to be polished can be stabilized at all times, eliminating the uneven support rigidity of the object to be polished caused by conventional pack pads. is suppressed, and deterioration of the flatness of the object to be polished can be prevented.

(2) By forming the polishing plate from a porous material, the vacuum adsorption force of the object to be polished can be applied uniformly to the entire surface of the object to be polished, thereby improving the adsorption force of the object to be polished. At the same time, it is possible to improve the flatness accuracy.

(3) By forming the vacuum/pressure holes of the polishing plate into a lattice and slit shape, or a porous shape,
A non-contact surface is formed on the suction surface of the polishing plate, which reduces the supporting area of the object to be polished.As a result, unlike conventional methods, foreign matter in the environment that adheres to the back surface and suction surface of the object can be removed. It is possible to prevent the polishing pressure from increasing and the polishing rate from increasing locally, and it is possible to prevent flatness from deteriorating due to foreign matter.

(4) In the polishing plate, by arranging a seal member at the outer periphery of the object to be polished on the suction surface of the object to be polished,
Since it is possible to prevent abrasives from entering between the object to be polished and the polishing plate, it is possible to prevent surface roughening due to secondary crevice corrosion and local corrosion on the back side of the object to be polished. be.

(5) By setting the internal pressure of the vacuum/pressure hole of the polishing plate to negative pressure or positive pressure, the attachment and detachment of the object to be polished can be performed automatically, so the attachment and detachment of the object to be polished can be automated. It is possible to obtain a polishing device capable of polishing.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part showing a polishing plate of a polishing apparatus which is an embodiment of the present invention, FIGS. 2 to 5 are enlarged sectional views of main parts showing modifications of the polishing plate of this embodiment, FIG. 6 is a plan view showing the suction surface of the polishing plate in FIG. 5, FIG. 7 is a front view schematically showing the polishing device of this embodiment, and FIG. 8 is a diagram showing the polishing plate of the polishing device of this embodiment. FIG. DESCRIPTION OF SYMBOLS 1... Wafer (object to be polished), 1a... Orientation flat, 2... Polishing device (polishing device), 3... Polishing surface plate, 3a... Drive shaft, 4... Polishing cloth , 5... Polishing plate, 5a... Vacuum...
Pressure hole, 5b... Mounting groove, 5C... Conical groove, 6
...Pressure cylinder (research load loading mechanism), 7...0
Ring (sealing member), 8... Abrasive, 9... Driven wheel, 9a... Vacuum/pressure hole, 10... Bearing, 11...
...Torker arm, 12...Template, 12a
... Mounting hole, 13... Porous adsorption plate (porous material), 14... Sealing agent (noodle member), 15...
Edge sealing material (sealing material). 7: 0 ring (sealing member) 1-0 4; Polishing cloth 5: Polishing plate 6: Pressure cylinder (polishing load loading mechanism)

Claims (1)

[Claims] 1. A polishing cloth for polishing a plate-like object to be polished, a polishing plate for holding the object to be polished, and a polishing load loading mechanism for pressurizing the polishing plate with a predetermined pressure. 1. A polishing apparatus of a waxless type, characterized in that the object to be polished is directly held on the suction surface of the polishing plate by vacuum suction. 2. Claim 1, wherein the polishing plate is a polishing plate made of a porous material, and the adsorption force to the object to be polished is applied uniformly to the entire surface of the object to be polished. polishing equipment. 3. Claim 1, wherein the vacuum/pressure holes of the polishing plate are formed in a grid, slit shape, or porous shape, so that the contact area with the object to be polished is reduced.
The polishing device described. 4. The polishing plate has a sealing member disposed at the outer periphery of the object to be polished on the suction surface of the object to be polished, and the sealing member prevents abrasive from entering between the object to be polished and the polishing plate. The polishing apparatus according to claim 1, 2 or 3, wherein the polishing apparatus is prevented from being damaged. 5. The object to be polished is attached and detached by setting the internal pressure of the vacuum/pressure hole of the polishing plate to a negative pressure or a positive pressure. Polishing equipment.