JP2003260661A - Wafer polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain low equipment cost, short manufacturing time, and labor saving by performing smooth polishing in two stages of double-surface rough- polishing and single-surface finish polishing with a relatively simple device. <P>SOLUTION: This device includes a lower surface plate 1 in which a polishing element for rough-polishing 4 is stuck and a wafer is placed and restrained, a first upper surface plate 12 in which a polishing device for rough-polishing 18 is stuck, a second upper surface plate 13 in which the polishing device for finish polishing 19 is stuck, and an exchanging means 21 for exchanging the first upper surface plate 12 with the second upper surface plate 13 to the wafer placed and held on the lower surface plate 1. In both the processes of the double-surface rough-polishing and the single-surface finish polishing, the wafer is placed and restrained on the lower surface plate 1, and the first upper surface plate for double-surface rough-polishing 12 and the second upper surface plate 13 for the single-surface finish polishing are exchanged for the wafer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer polishing apparatus capable of smoothly performing double-sided rough polishing of a wafer and subsequent single-sided finish polishing with a single apparatus.

[0002]

2. Description of the Related Art Generally, a method of manufacturing a semiconductor wafer such as Si or GaAs is as follows. First, after slicing a crystal ingot to cut out a wafer, the flatness is increased by lapping or surface grinding, and then etching is performed for removing processing strain and cleaning. Next, polishing is performed to make both surfaces of the wafer mirror-finished. Polishing is carried out in two stages: double-sided rough polishing for simultaneously polishing both sides of the wafer and single-sided finish polishing for finish-polishing only one side. Double-sided rough polishing is performed by setting a resin carrier with holes of about the same diameter as the wafer on the lower surface plate to which a non-woven type polishing cloth is attached, setting the wafer in the holes of the carrier, and then using the non-woven type polishing cloth. The upper surface plate to which is attached is lowered and pressure is applied, and the upper surface plate, the lower surface plate and the carrier are rotated, respectively, and polishing is performed while flowing a polishing liquid. The wafer after the double-sided rough polishing is attached to a ceramic attachment jig with wax, and single-side finish polishing is performed in order to finish one side of the wafer into a further mirror surface. Single-sided finish polishing is performed by lowering the jig on which the wafer is attached to the lower surface plate on which a soft polishing cloth with a foamed polyurethane surface structure is attached, applying pressure, and rotating the jig and lower surface plate, respectively, and polishing while flowing the polishing liquid. To do. After the polishing is completed, the wafer is removed and cleaning is performed to remove the wax on the back surface. Finally, in order to remove impurities on the wafer surface, cleaning is performed with a cleaning liquid having a very weak etching action.

[0003]

However, in the two-step polishing method of double-sided rough polishing and single-sided finish polishing described above, two types of polishing machines, a double-sided rough polishing machine and a single-sided finish polishing machine, are required. Therefore, a large equipment cost is required. Further, a wafer attaching step before the one-side finish polishing, a wafer removing step after the one-side finish polishing, and a wax removing and cleaning step on the back surface of the wafer are required, which takes time and labor.

Therefore, an object of the present invention is to realize two-stage polishing, ie, double-sided rough polishing and single-sided finish polishing, with a relatively simple device, to keep equipment costs low, and to carry out the wafer attaching step and the wafer removing step. , And the step of removing and cleaning the wax on the wafer surface is omitted, and the wafer is manufactured with a small amount of time and labor.

[0005]

A wafer polishing apparatus according to the present invention comprises a lower polishing plate on which a polishing element for rough polishing is attached and a wafer is placed and held, and a first polishing element on which a polishing element for rough polishing is attached. An upper platen and a second upper platen to which polishing elements for finish polishing are attached are provided, and after the double-sided rough polishing of the wafer is performed by the lower platen and the first upper platen, continuous In order to perform one-side finish polishing of the wafer on the second upper platen, the first upper platen and the second upper platen are placed on the wafer held and held on the lower platen. An exchange means for exchanging with is provided.

Here, the exchanging means connects the first upper surface plate and the second upper surface plate, and an arm member for rotating them around a common rotation axis, and an arm member for rotating the arm member. It is preferable to include a turning drive means for driving and a lifting drive means for lifting and lowering the arm member.

Further, the first upper platen has a polishing liquid supply means for rough polishing for supplying a polishing liquid for rough polishing at the time of double-sided rough polishing of the wafer, and the second upper platen is It is preferable to have a polishing liquid supply means for final polishing for supplying a polishing liquid for final polishing at the time of one-side finish polishing of the wafer.

According to the present invention, the wafer is still placed and held on the lower surface plate in both steps of the double-sided rough polishing and the single-sided finish polishing. The plate and the second upper surface plate for one-side finish polishing are exchanged. This makes it possible to perform two-step polishing of double-sided rough polishing and single-sided finish polishing with one simple device, and to omit the wafer attaching step, the wafer removing step, and the wax removing and cleaning step of the wafer surface, which is small. Two-step polishing of the wafer can be realized with time and labor.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a wafer polishing apparatus according to this embodiment. Reference numeral 1 is a lower surface plate fixed to the fixed side.
Is mainly composed of a lower support base 2 on the fixed side, an upper rotary disk 3 on the rotary side, and a rough polishing polishing cloth 4 attached or laid on the upper surface of the rotary disk 3. The rough polishing polishing cloth 4 forms a polishing element for rough polishing, and here, for example, a non-woven cloth type polishing cloth is used. A plurality of semiconductor wafers are placed and held on the upper surface of the polishing cloth 4 for rough polishing by using the carrier 5.

As shown in FIG. 2, as the carrier 5, a planetary gear type carrier is used here, and the rotatable sun gear 6 located at the center of the lower turn table 1 and the outer peripheral end of the lower turn table 1 and particularly the turntable 3 are used. A ring gear 7 having internal teeth fixed to the edge,
The sun gear 6 and the ring gear 7 are mainly configured to include a plurality of planetary gears 8 (here, five gears) meshed with both gears. The sun gear 6 is attached to a rotary drive shaft (not shown) that penetrates the rotary disk 3 and can rotate relative to the rotary disk 3. The planetary gear 8 is made of, for example, a resin, is arranged on the upper surface of the polishing cloth 4 for rough polishing, and has a plurality (here, eight) of holes 10 into which one wafer 9 is fitted (set). . That is, here, 40 wafers 9 are simultaneously polished.

A motor (not shown) as a driving means for independently rotating and driving the rotary disk 3 and the sun gear 6 is provided in the support base 2, and the rotary disk 3 and the sun gear 6 are rotated in the direction shown. It In particular, the rotation of the sun gear 6 causes the planetary gear 8 to rotate and revolve as shown in the figure, whereby the lower surface of the wafer 9 slides on the polishing cloth 4 for rough polishing.

In order to polish the upper surface of the wafer 9, the thickness of the ring gear 7 and the planetary gear 8 is made smaller than the thickness of the wafer 9, whereby the upper surface of the wafer 9 is projected with respect to the ring gear 7 and the planetary gear 8. It On the other hand, a projection shaft 11 for aligning the lower surface plate 1 and the upper surface plate is provided above the sun gear 6, and the sun gear 6 is projected above the wafer 9.

In particular, in this apparatus, in order to perform both the double-sided rough polishing and the single-sided finish polishing of the wafer 9, the first upper surface plate 12 for the double-sided rough polishing and the second upper surface plate for the single-sided finish polishing. A surface plate 13 is provided. These upper surface plates 12, 13
Has the same structure except that the polishing elements are different.

These upper surface plates 12 and 13 are the surface plate body 14
And a rotary platen 16 connected to the upper surface of the platen body 14 through a plurality of connecting stays 15, and an upper platen rotation for driving the rotary platen 16 to rotate the upper platens 12 and 13 as illustrated. And a motor 17 as a means. Further, a polishing element is attached or laid on the lower surface of the surface plate main body 14, and as the polishing elements, a polishing cloth for rough polishing 18 of the first upper surface plate 12 and a second upper surface plate 13 are used. Then, the polishing cloth 19 for finish polishing. The rough polishing polishing cloth 18 is, for example, a non-woven type polishing cloth, and the final polishing polishing cloth 19 is, for example, a relatively soft polishing cloth having a foamed polyurethane surface structure. Further, each upper platen 12, 13 is provided with a polishing liquid supply means, which is a plurality of polishing liquid supply hoses 2.
0 and holes (not shown) formed through the hose 20 and penetrating the surface plate body 14. The rough polishing liquid is supplied from the first upper surface plate 12 side, and the finish polishing liquid is supplied from the second upper surface plate 13 side from the back side of the polishing cloths 18 and 19, respectively. Surface plate body 14 and polishing cloth 1
A positioning hole 26 for fitting the above-mentioned protruding shaft 11 is provided at the center with respect to 8 and 19.

Then, in order to replace the first upper surface plate 12 and the second upper surface plate 13 with respect to the wafer 9 placed and held on the lower surface plate 1, the present apparatus is provided with an exchange means 21. The exchange means 21 includes a first upper surface plate 12 and a second upper surface plate 13
Of the arm member 22 for rotating the arm member 22 around a common turning axis O, a swing driving means for driving the arm member 22 to swing, and a lift driving means for lifting the arm member 22. Is composed of.

The arm member 22 has a turning axis O extending vertically.
A rotatable member 23 rotatable around and a motor 1 for the first upper surface plate 12 and the second upper surface plate 13 extending from the rotation member 23.
It is integrated with a first arm 24 and a second arm 25 which are respectively connected to 7. The first arm 24 and the second arm 25 extend from the rotating member 23 at a predetermined angle to each other, and position the first upper surface plate 12 and the second upper surface plate 13 at the same radial distance from the turning axis O. Let As a result, the first upper platen 12 and the second upper platen 13 are
By the turning motion of 2, move horizontally on the same circular orbit,
It comes to be located right above the lower surface plate 1 at one place on the circular orbit. Although not shown, the turning drive means is composed of a motor or the like for rotationally driving the rotating member 23, and the lifting drive means is composed of a cylinder or a motor or the like for lifting and lowering the support side of the rotating member 23.

Next, a method of polishing a wafer by this apparatus will be described.

First, from the state shown in FIG.
Is rotated, the first upper platen 12 is positioned directly above the lower platen 1, the arm member 22 is lowered, and the first upper platen 12 is pressed against the wafer 9 with a predetermined pressure. At this time, the protruding shaft 11
Using the and positioning holes 26, both surface plates are aligned with each other. Then, while supplying the polishing liquid for rough polishing by the polishing liquid supply means of the first upper platen 12, the rotary plate 3, the carrier 5, and the platen body 14 are rotated as shown in the drawing. Then, the upper surface and the lower surface of the wafer 9 are respectively provided with polishing cloths 18 and 4 for rough polishing.
With this, polishing is performed under pressure, and double-sided rough polishing is performed.

After the completion of the double-sided rough polishing, the supply of the polishing liquid and the rotation are stopped, and the arm member 22 is raised to separate the first upper platen 12 from the wafer 9. Then, in order to remove the residual polishing liquid, the wafer 9, the carrier 5 and the polishing cloth 4 on the lower surface plate 1 are washed with a pure water shower ejected from a shower nozzle (not shown).

After that, the arm member 22 is swung in the opposite direction to the first, and the second upper surface plate 13 is positioned directly above the lower surface plate 1. Then, in the same manner as described above, the second upper platen 13 is lowered and pressed against the wafer 9, the polishing liquid supply means of the second upper platen 13 supplies the polishing liquid for final polishing, and the rotary plate 3, carrier 5, The platen body 14 is rotated as shown. Then, the lower surface of the wafer 9 is still roughly polished, but the upper surface of the wafer 9 is polished by the polishing cloth 19 for finish polishing under pressure and single-side finish polishing is performed.

As described above, since the two-step polishing including the double-sided rough polishing and the single-sided finish polishing can be continuously and smoothly performed by one relatively simple apparatus, the equipment cost can be kept low and the wafer can be reduced. The attaching step, the wafer removing step, and the wax removing and cleaning step for the wafer surface can be omitted, and the wafer can be manufactured with less time and labor. As a result, it is possible to significantly reduce the lead time and cost.

Various other embodiments of the present invention are possible. For example, the exchanging means may be a linear reciprocating type instead of the above-described turning type.
The polishing element may be a grindstone or the like. Various methods of mounting and holding the wafer on the lower surface plate can be considered.

[0024]

EXAMPLE A wafer was actually polished by using the above apparatus. The wafer to be polished is Ga with a diameter of 100 mm.
As wafers, the surface plate diameter of each surface plate 1, 12, 13 is 116.
It is 1 mm. Nonwoven fabric type polishing cloths were used as the rough polishing polishing cloths 4 and 18, and foamed polyurethane type polishing cloths were used as the final polishing polishing cloth 19. At the time of rough polishing, the rotating plate 3 of the lower platen 1 is rotated at a rotation speed of 20 rpm, the platen body 14 of the first upper platen 12 is rotated at a rotation speed of 7 rpm, and the polishing liquid for rough polishing is 750 ml / Flowed at a flow rate of min. The rough polishing time is 50 minutes. After that, washing with a pure water shower was carried out. At this time, only the turntable 3 of the lower turn table 1 was rotated at a rotation speed of 5 rpm. In the final polishing after washing with water, the lower turntable 3 is rotated at a rotation speed of 40 rpm, and the turntable body 14 of the second upper turntable 13 is moved to 14 rpm.
Rotate at a rotation speed of rpm to remove the polishing liquid for final polishing.
Flowed at a flow rate of 000 ml / min. The finish polishing time is 20 minutes. Immediately after this finishing polishing, the second upper surface plate 1
3 was moved up and the pure water shower was quickly applied to the wafer to wash the wafer with water while rotating only the rotary plate 3 of the lower surface plate 1 at a rotation speed of 5 rpm.

With respect to the wafer thus polished, the surface roughness is examined with a microscope, and the flatness measuring device (Supersort manufactured by Tropel) is used to perform TTV (To
tal Thickness Value) and a mirror surface inspection device (KLA Tencor's Surfscan 62)
00) was used to examine the haze. For comparison, the same investigation was conducted on a wafer polished by the conventional method. The results are shown in Table 1.

[0026]

[Table 1]

As a result, it was confirmed that the quality of the wafer manufactured by the apparatus according to the present invention was exactly the same as that of the conventional method and there was no problem.

[0028]

In summary, according to the present invention, the following excellent effects are exhibited. (1) Since the two-step polishing of double-sided rough polishing and single-sided finish polishing can be performed by a relatively simple device, the equipment cost can be kept low. (2) A plurality of conventional steps can be omitted, and a wafer can be manufactured with less time and labor.

[Brief description of drawings]

FIG. 1 is a front view of a wafer polishing apparatus according to this embodiment.

FIG. 2 is a plan view of a lower surface plate side.

[Explanation of symbols]

1 Lower surface plate 4,18 Polishing cloth for rough polishing 9 wafers 12 First upper surface plate 13 Second upper surface plate 19 Polishing cloth for finish polishing 20 Polishing liquid supply hose 21 Exchange means 22 Arm member O swivel axis

Claims (3)

[Claims] 1. A lower surface plate on which a polishing element for rough polishing is attached and a wafer is placed and held, a first upper surface plate on which a polishing element for rough polishing is attached, and a polishing element for finish polishing are attached. Provided with the second upper surface plate provided, after performing the double-sided rough polishing of the wafer with the lower surface plate and the first upper surface plate of the above In order to perform one-side finish polishing, an exchanging means for exchanging the first upper surface plate and the second upper surface plate with respect to the wafer mounted and held on the lower surface plate is provided. Wafer polishing machine. 2. An arm member for connecting the first upper surface plate and the second upper surface plate to rotate them around a common swivel axis, and a swivel drive of the arm member. 2. The wafer polishing apparatus according to claim 1, further comprising a turning drive means for moving the arm member, and a lifting drive means for lifting the arm member. 3. The first upper platen has a polishing liquid supply means for rough polishing for supplying a polishing liquid for rough polishing during double-sided rough polishing of the wafer, and the second upper platen is 3. The wafer polishing apparatus according to claim 1, further comprising a polishing liquid supply device for final polishing for supplying a polishing liquid for final polishing at the time of single-sided polishing of the wafer.