JP3247708B2 - Polishing equipment for semiconductor wafers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing (mirror polishing) a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, to polish a semiconductor wafer such as silicon, a plurality of wafers are bonded to one surface of a flat plate with wax or the like, and then, a polishing cloth attached to a surface plate is placed on a polishing cloth. The plate is placed on the lower side, the top ring rotatably suspended on the vertical moving spindle is lowered, and the wafer bonded to the lower surface of the plate is pressed against the polishing cloth, and a special slurry is applied to the polishing cloth surface. The platen is rotated while supplying, and the plate is rotated together with the top ring to mirror-process the wafer.

[0003]

In this case, in order to perform mirror polishing with high precision on the wafer, it is necessary to uniformly press the entire surface of the plate with the wafer adhered to the lower surface by the top ring. However, in the conventional polishing apparatus, for automation of the apparatus, the top ring is fixed to the lower part of the vertical movement mechanism located on the vertical line of the plate, and the top ring remains fixed to the vertical movement mechanism even when the wafer is pressed. Therefore, if the mounting angle of the vertical movement mechanism with respect to the top ring is not exactly right, the plate will not be pressed down vertically. Usually, even a single wafer has variations in thickness,
Since a plurality of wafers are bonded to the plate, an error occurs in the horizontality of the upper surface of the plate. In an extreme case, there is a possibility that a portion of the upper surface of the plate that does not contact the top ring, that is, a portion that is not pressed down at all, may occur. further,
Fine surface run-out may occur on the surface of the surface plate during the mirror polishing of the wafer, but even in that case, the top ring remains fixed to the vertical movement mechanism, so that high-precision processing could not be performed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has no problem with the flatness of the upper surface of a wafer to be processed.
It is an object of the present invention to provide a wafer polishing apparatus capable of always pressing the wafer evenly and coping with the runout of the surface of the platen during processing.
The semiconductor wafer polishing apparatus puts a plate on which a semiconductor wafer is adhered to a lower surface on a polishing cloth attached to a surface plate, and polishes the wafer by pressing down with a top ring suspended from a vertically moving spindle. In a wafer polishing apparatus, a top ring is composed of a disk-shaped head for pressing down a plate, a central shaft vertically erected at the center, and an annular weight stacked on the head through the central shaft. The main shaft has a top ring support member that spreads downward at the lower end, the central shaft is cylindrical, accommodates the top ring support member inside the upper part, and forms a stopper that narrows upward at the upper end,
The maximum outer diameter of the top ring support member is smaller than the inner diameter of the cylindrical part of the central shaft, but larger than the inner diameter of the stopper.
When the vertically moving spindle rises, the top
The ring support member and the stopper engage with each other, and
The top ring is lifted so that it can be suspended
When the lower spindle moves down, the top ring moves from the vertical spindle.
Separate and press down the top of the plate by its own weight.
The present invention provides a polishing apparatus for a semiconductor wafer, characterized in that the polishing apparatus is formed.

[0005]

The device of the present invention will be described below with reference to the drawings.
1A and 1B show an embodiment of a polishing apparatus according to the present invention, wherein FIG. 1A is a cross-sectional view taken along line AOB of FIG.
FIG. 2B is a partial plan view, in which a plurality of semiconductor wafers 2 to be processed are adhered to the lower surface of the plate 1, and the semiconductor wafers 2 are mounted on a polishing cloth 4 attached to the upper surface of the surface plate 3. The top ring 5 comprises a circular head 6 which comes into contact with and lowers the plate 1 and a central shaft 7 erected perpendicularly at the center thereof. On the head 6, an annular weight 8 penetrates the central shaft 7. As many as necessary.

Although the center shaft 7 is cylindrical, the inside thereof becomes narrower upward and a stopper 9 is formed at the upper end. The vertically moving main shaft 10 has a top ring support member 11 that spreads downward at the lower end. Although the top ring support member 11 is accommodated inside the cylindrical central shaft 7, the upper inner surface of the central shaft 7 becomes narrower upward to become the stopper 9, and the inner diameter at the upper end is equal to the top ring support member. 11 is smaller than the maximum outer diameter of the vertical moving spindle 10.
Does not fall out of the central shaft 7 even if the height is raised. Also, since the inner diameter of the central shaft 7 below the stopper 9 is larger than the maximum outer diameter of the top ring supporting member 11, the vertical moving main shaft 10 can be lowered without bringing the top ring supporting member 11 into contact with the inner surface of the central shaft 7. it can.

Therefore, when the vertically moving main shaft 10 is lifted, the top ring support member 11 comes into contact with the stopper 9 and the top ring 5 is lifted. If the shape of the inner peripheral surface of the stopper 9 and the shape of the outer peripheral surface of the top ring support member 11 match, the top ring can be stably lifted without wobbling. Conversely, when the vertical movement spindle 10 is lowered, the top ring 5 reaches the lowering limit of the top ring 5 when the head 6 of the top ring comes into contact with the plate 1, and the vertical movement spindle 10 is further lowered. The contact between the support member 11 and the stopper 9 is released, and the top ring is separated from the vertically movable main shaft 10 of the top ring, and is simply placed on the plate 1. In this way, the top ring is separated from the vertical moving spindle and placed on the plate, so it is always horizontal with respect to the plate upper surface. Even if it is not horizontal, it contacts the entire surface of the plate and uniformly reduces the pressure. Also, since the top ring follows the inclination of the upper surface of the plate, it can completely follow the surface runout of the surface plate generated during machining, and the weight 8 can be increased or decreased to appropriately reduce the rolling force by the top ring. If the value is adjusted, the wafer can be polished under constant processing conditions throughout.

However, the top ring 5 is separated from the vertical moving spindle 10 during wafer processing, and can move freely on the surface plate to some extent without being restrained in the horizontal direction. Can not be done. Therefore, a center roller 12 is provided near the polishing plate 4 at the center of the platen and a guide roller 13 is provided near the polishing cloth at the periphery of the platen so as to contact the side surface of the top ring. And the plate 1 is held at a fixed position on the surface plate to restrict horizontal movement.

Here, the center roller 12 is provided with a rotation drive source, and while the center roller is rotated, the plate 1 in contact with the center roller 12 is rotated to mirror-process the wafer. The top ring is rotated by friction, and a rotational force other than the rotation of the platen 3 acts on the top ring, so that a good mirror finish can be performed.

At this time, since the top ring 5 is only rotating due to the contact friction with the center roller 12, some load is temporarily applied to the top ring,
Even if the smooth rotation of the top ring is hindered, the contact portion between the top ring and the center roller slips, and no excessive force is applied to the top ring, so that good polishing is performed.

Further, by providing a moving arm 14 for moving the guide roller 13 between a position where the guide roller 13 contacts the side surface of the plate 1 and a position where the guide roller 13 does not contact the plate 1, a plurality of plates rotating on the platen are successively placed. It is possible to hold the wafer at a fixed position on the upper side and to sequentially discharge the plate to which the processed wafer is bonded, automate the machine together with the vertical movement mechanism of the top ring, and process multiple plates at the same time This makes it possible to increase the efficiency of the polishing process.

Further, the lower surface of the top ring forms a concave portion 15 opened downward, and the concave portion is covered with an elastic film 16 to form a closed space 17 between the concave portion of the lower surface of the top ring and the elastic film. By providing the fluid supply nozzle 18 for supplying the pressure fluid to the center of the closed space, more uniform pressure reduction can be performed. That is, the total load applied to the plate 1 is determined by the weight of the top ring 5, but when the fluid supply pressure inside the closed space 17 is increased, the elastic film 16 becomes convex downward,
The rolling force applied from the center of the tire increases. Conversely, when the fluid supply pressure is reduced, the elastic film 16 becomes concave downward, and the rolling force applied from the periphery of the head increases.
As described above, by performing the polishing while deforming the elastic film 16 according to the situation and flowing the slurry from the slurry supply pipe 19 onto the polishing cloth 4, it is possible to realize a highly accurate wafer polishing. It is. In addition, by equipping the lower surface of the head of the top ring with a bag made of an elastic body having a fluid supply mechanism therein, the entire surface of the plate in contact with the bag can be uniformly pressed down.

[0013]

According to the present invention, the top ring is vertically
When the moving spindle rises, the upper and lower
Stably suspended by the top ring support member at the lower end of the shaft
When the vertical spindle is lowered, the top ring is separated from the vertical spindle, and the plate is pressed down by its own weight including the weight.Thus, even if the wafers have uneven thickness, etc., uniform polishing is performed. It can completely follow the run-out, and can mirror-process under constant conditions from start to finish. In addition to the top ring of the polishing apparatus, a good result can be obtained even if the pressing platen such as a lapping apparatus is separated from the vertically movable main shaft during processing and pressurized by its own weight as in the present invention.

[Brief description of the drawings]

FIG. 1A is a sectional view taken along line AOB of FIG. 1B;
(B) is a partial plan view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate 2 Wafer 3 Surface plate 4 Polishing cloth 5 Top ring 6 Head 7 Central axis 8 Weight 9 Stopper 10 Vertical movement main shaft 11 Top ring support member 12 Center roller 13 Guide roller 14 Moving arm 15 Depression 16 Elastic film 17 Sealed space 18 Nozzle 19 Slurry supply pipe

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B24B 37/04 B24B 37/00 H01L 21/304 621 H01L 21/304 622

Claims (5)

(57) [Claims] 1. A plate having a semiconductor wafer adhered to a lower surface is placed on a polishing cloth attached to a surface plate, and the plate is vertically moved.
The wafer is rolled down by a top ring suspended from the shaft.
In a polishing device for semiconductor wafers to be polished, a top ring is a disk-shaped head that presses down a plate.
And a central axis that stands perpendicularly to this center, and penetrates the central axis.
And consist of annular weights stacked on the head,
The vertically moving main shaft has a top ring supporting member that spreads downward at the lower end, and the central shaft is cylindrical,
Accommodates the ring support member and narrows upward at the upper end
Form a stopper that is no longer
Although the maximum outer diameter is smaller than the inner diameter of the cylindrical part of the central shaft,
The top ring is formed so as to be larger than the inner diameter of the par and the top ring supporting member and the stopper are engaged at the upper end of the central shaft when the vertically moving main shaft is raised , and the top ring is suspended so as to be suspended at the engaged portion. lifted, during the descent of the vertical movement spindle, a semiconductor wafer polishing apparatus characterized by the top ring is configured to pressure the plate upper surface by its own weight is decoupled from the vertical movement spindle. 2. The top ring is close to the platen at the center of the platen.
Center roller provided in contact with the periphery of the platen
It is held in contact with a guide roller provided close to the board.
2. The device of claim 1, wherein the device is rotated. 3. The center roller is strengthened by a rotary drive source.
3. The device according to claim 1, wherein the rotation is stopped. 4. The guide roller has a center roller and a center roller.
Position where the top ring is sandwiched between and held in contact with it
And wherein it can be moved to a position where it is not held.
An apparatus according to any of the preceding paragraphs. 5. The lower end of the top ring has a downwardly open recess.
Pressure flow into the enclosed space created by covering this with an elastic membrane.
2. The device according to claim 1, wherein the nozzle for supplying the body is open.
Place.