JP3118457B2 - Wafer polishing method and top ring used for it - Google Patents

Description

The present invention relates to a method for polishing a wafer such as a silicon semiconductor and a top ring for a wafer polishing apparatus used in the method.

[Prior Art] Conventionally, when a wafer such as a silicon semiconductor is mirror-polished, a polishing apparatus as shown in FIG. 2 has been practically used.

That is, the wafer 1 is attached to one surface of the plate 2,
The wafer 1 is placed on the polishing platen 3 with the wafer 1 facing down, and the upper surface of the plate 2 is pressed by the inverted dish-shaped head 5 of the top ring 4 ,
The wafer 1 is polished by rotating the polishing platen 3 and the top ring 4 . The pressing force on the wafer 1 is placed on the head 5 and adjusted by adjusting the amount of the ring-shaped weight 6 that rotates together with the head.

[Problems to be Solved by the Invention] However, in such an apparatus, since the plate 2 on which the wafer 1 is stuck and the head 5 are rotating integrally, if the balance of the pressing of the head 5 is slightly out of order, This unbalance affects the respective wafers in the same state from the beginning to the next, and the wafer 1 is strongly pressed or weakly pressed depending on the attaching position, and has a disadvantage that the polishing is unevenly performed and the quality is deteriorated.

[Means for Solving the Problems] The present inventor has completed the present invention as a result of repeated studies to solve such disadvantages, and the present invention has been described in claims 1 and 2 above. The subject matter is a wafer polishing method and a top ring used in the method. Thus, the present invention has a technical feature in particular in the structure of the top ring, in which the periphery of the inverted dish-shaped head below the top ring is formed into a recess formed by projecting downward. A mounting table for adjusting the pressure and a weight for weight adjustment placed above the inverted dish-shaped head at the bottom of the top ring is fixed to the main shaft of the top ring during the rotation polishing work of the top ring It is characteristic that the wafer is polished in a state where it is held in a non-rotational manner by the rotation-preventing arm that has been made.

As a result of stopping the rotation of the weight by the rotation preventing means in the apparatus of the present invention, each wafer moves independently of the weight, and the movement locus passes through each part of the pressing surface of the weight, so that the pressing force is balanced. Even without this, the wafer is pressed uniformly and high-precision polishing is performed.

 Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an apparatus for performing the method of the present invention.
The polishing platen 3 comprises a horizontally rotating turntable 7 and a cloth 8 adhered on the turntable 7, and a rotatable top ring 4 is suspended from above on the outer periphery thereof. An inverted dish-shaped head 5 is provided at the lower part of the top ring, and a flexible thin film 9 is attached to the periphery thereof, and fluid is press-fitted from a fluid supply pipe 10 into a closed space formed by the head and the thin film. Next, the plate 2 with the wafer 1 attached to one surface is placed on the cloth 8 directly below the top ring 4 with the wafer side down, and the top ring 4 is lowered to press the plate with the lower surface of the flexible thin film 9. I do. Then, the pressure of the fluid injected from the fluid supply pipe 10 is adjusted so that the flexible thin film 9 uniformly presses the plate 2 over the entire surface. When the top ring 4 is rotated by a rotation mechanism (not shown), the lower surface of the wafer 1 is polished by the cloth 8. At this time, the pressing force is adjusted by adjusting the amount of the weight 6 and the wafer is polished at an appropriate polishing rate. Alternatively, the weight 6 is placed on the mounting table 12 and is not rotated by the rotation preventing arm 13 penetrating the weight. Since it is fixed to the ring main shaft 14, the weight 6 does not rotate even if the head rotates. Since the mounting table is in contact with the top ring spindle holding portion 15 via the ball bearing 16, the mounting table does not hinder the rotation of the head.

With this configuration, the movement trajectory of the wafer uniformly passes through the respective parts of the weight, and the wafer 1 is uniformly pressed and polished.

[Effects of the Invention] According to the present invention, even if the weight is imbalanced with respect to the wafer, the wafer relatively moves with respect to the weight, and as a result, uniform polishing is performed and a high-quality wafer can be obtained. .

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a wafer polishing apparatus having a top ring according to the present invention, and FIG. 2 is a partial sectional view of a conventional wafer polishing apparatus. DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Plate, 3 ... Polishing platen, 4 ... Top ring, 5 ... Head, 6 ... Weight, 7 ... Turnteheble, 8 ... Cross, 9 ... Flexible thin film 10 Fluid supply pipe, 11 Nozzle, 12 Mounting table, 13 Anti-rotation arm, 14 Top ring spindle, 15 Top ring spindle holder, 16 Ball bearing.

Claims (2)

(57) [Claims] 1. A wafer attached to a plate is applied to a cloth adhered to an upper surface of a turntable of a polishing platen, and the plate is pressed from above by a top ring on which a weight for adjusting a pressing force is placed. In a method of polishing a wafer by relative sliding while rotating the turntable and the top ring, a cylindrical portion protruding below the inverted dish-shaped head below the top ring, and a seal at the lower end opening. A fluid is injected into a sealed space formed by the attached flexible thin film, the pressure of the fluid is adjusted, and a fluid is injected into a mounting table held via a ball bearing on a spindle holding portion of a rotating top ring. A weight for pressure adjustment is placed, and the weight is non-rotatable with the mounting table by a rotation preventing arm fixed to the main shaft of the non-rotating top ring. Wafer polishing method characterized by polishing to hold. 2. An apparatus for polishing a wafer by applying a wafer attached to a plate to a cloth adhered to the upper surface of a turntable of a rotating polishing platen and pressing and rotating the plate from above. The top ring has an inverted dish-shaped head at the bottom, and a closed space is formed in the head by a cylindrical portion protruding downward and a flexible thin film hermetically attached to an opening at the lower end thereof. The space is filled with a fluid by a fluid supply pipe to adjust the pressure of the fluid, and a mounting table on which a weight for adjusting the pressing force is mounted is held via a ball bearing on a main shaft holding portion that rotates above the head. A top ring for wafer polishing, wherein a weight for adjusting the pressing force placed on the mounting table is held non-rotatably by a rotation preventing arm fixed to a main shaft.