JP3218572B2 - Polishing plate for wafer pressing - 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 plate for a polishing apparatus for mirror-finishing the surface of a thin wafer such as a silicon semiconductor.

[0002]

2. Description of the Related Art Conventionally, a polishing apparatus for mirror-polishing a semiconductor wafer surface has a plurality of wafers bonded to a flat plate, and the plate is polished on a rotating platen having a polishing cloth attached to a polishing surface. Place the wafer in contact with the cloth, press the plate with the polishing plate, press the wafer against the polishing cloth, rotate the rotating platen while supplying the slurry, and rotate the plate to mirror-process the wafer. Polishing apparatuses have been used.

[0003]

However, when a plurality of wafers are attached to a flat plate as described above,
If the individual wafers have slight thickness unevenness, the pressing force is not constant, and good polishing becomes impossible. In a single-wafer type polishing apparatus that processes wafers while pressing them one by one with a polishing plate, unlike a batch type polishing apparatus, the variation in the pressing force due to the thickness unevenness does not matter so much, but the number of wafers that can be processed simultaneously is Inevitably, there is a problem that the processing efficiency is poor and the productivity is inferior. In recent years, higher precision processing of wafers has been required, and it is essential to perform polishing while constantly pressing the entire surface of the wafer at a constant pressure. There was unevenness, and there was no polishing apparatus that completely satisfied the above processing conditions. Furthermore, regardless of the batch type or the single-wafer type, the wafer or the plate on which the wafer is bonded is rotated at a fixed position while being in contact with the rotating platen on which the polishing cloth is stuck. The trajectory follows the same ring-shaped trajectory every time, and as the processing is performed, only the wafer contact portion of the polishing cloth wears in a concave shape, but the edge portion is not perpendicular to the wafer but is inclined. Therefore, there is a problem that the peripheral portion of the wafer abutting on the edge portion is also processed with an inclination.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to always uniformly press the entire surface of a wafer irrespective of unevenness in the thickness of the wafer, and to reduce processing defects due to deformation of a polishing cloth. It is an object of the present invention to provide a batch processing type polishing plate for processing a wafer, which can be prevented.

[0005]

Means for Solving the Problems As means for technically solving this problem, the present invention provides a method in which a wafer is brought into contact with a rotating platen on which a polishing cloth is stuck, and the wafer is brought into contact with the polishing cloth by a polishing plate. Pressing, in the polishing plate of the polishing apparatus that performs mirror polishing of the wafer while supplying the slurry, a sealed space formed inside the polishing plate, and a fluid supply nozzle that supplies and removes fluid in the sealed space,
A plurality of wafer pressurizing sections each having an independent fluid chamber provided between the polishing plate and an elastic film attached thereto, and a fluid supply hole for communicating each of the fluid chambers and the closed space, respectively. And a polishing plate for pressurizing a wafer having the following. Further, in this wafer pressing polishing plate, a polishing cloth dresser is provided on at least the outer peripheral portion of the wafer pressing portion on the lower surface of the polishing plate, and further, an arc portion and an orientation flat portion corresponding to the shape of the wafer to be processed. A template provided with a notch having a notch is attached to the elastic film, and a cushion material is interposed at a contact portion of the lower surface of the elastic film with the wafer.

[0006]

The fluid supplied from the fluid supply nozzle to the closed space inside the polishing plate is supplied to the fluid chamber of the wafer pressurizing unit through the fluid supply hole, and can uniformly apply pressure to the entire surface of the wafer pressurizing unit. it can. The wafer pressing section is formed of an elastic film and holds the wafer on the lower surface. The wafer is not pressured directly from the polishing plate, but is pressed by the internal pressure of the fluid chamber of the wafer pressing section. And pressed against the polishing cloth. or,
Even if the wafer has uneven thickness, the elastic film can easily absorb the uneven thickness. Furthermore, by providing a dresser for polishing cloth correction at least on the outer peripheral part of the wafer pressing part on the lower surface of the polishing plate, a wider range than the wafer contact part on the polishing cloth surface is constantly corrected during polishing processing, and the polishing cloth wafer It is possible to prevent only the contact portion from being worn in a concave shape.
In addition, by interposing a cushion material at the part where the lower surface of the elastic film contacts the wafer, rotation (slipping) of the wafer in the template is prevented, and both ends of the wafer orientation flat interfere with the template orientation flat. Can be prevented from being damaged.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a polishing plate, which comprises a disk-shaped upper body 1a having a concave portion on the lower surface side, and a lower body 1b tightly integrated with the upper body 1a via an O-ring 1c. The recess forms a closed space 2.

The upper body 1a is suspended and fixed at the center by a rotating main shaft 3, and a fluid supply nozzle 4 formed in the axial direction of the rotating main shaft 3 is communicated with the closed space 2 so that a fluid is supplied into the closed space 2. Can be supplied and removed.

As shown in FIG. 2, the lower body 1b has a plurality of (five) circular concave portions formed on the lower surface side in the circumferential direction.
An elastic film 5 made of an elastic material such as rubber is attached to the concave portion via a taper ring 6 to form fluid chambers 7 respectively. The space 2 is communicated with each other.

Therefore, when compressed air is supplied from the fluid supply nozzle 4 into the closed space 2, the compressed air flows into the fluid chamber 7 through the fluid supply hole 8 and applies an even pressure to the elastic membrane 5. be able to. That is, the elastic film 5 has an appearance like an air bag, and the wafer pressing portion 9 is formed in each concave portion.

Reference numeral 10 is a dresser for a polishing cloth in the form of a sheet, which is attached to the lower surface of the lower body 1b except for the wafer pressurizing section 9. Reference numeral 11 denotes a ring-shaped weight placed on the upper surface side of the upper body 1a.

In order to mirror-process a wafer W to be processed by using the polishing plate 1 having such a structure, first, the wafers W are respectively adhered to the elastic film 5 which is immersed in pure water and wetted. To the wafer pressurizing section 9. At this time, the wafer W is in close contact with the elastic film 5 that is wet with water, and the periphery is held by the taper ring 6.

Next, the polishing plate 1 is moved,
The wafer W held by the wafer pressing unit 9 is brought close to the polishing cloth C surface of the rotary platen T as shown in FIG. 3, and the dresser 10 on the lower surface of the polishing plate 1 is brought into contact with the polishing cloth surface. Place the whole on a rotating platen.

Thereafter, compressed air is supplied from the fluid supply nozzle 4 into the closed space 2, and the fluid chamber 7 of the wafer pressurizing section 9 is supplied.
The internal pressure is increased to expand the elastic film 5, and the wafer W is pressed against the polishing cloth C.

When the pressure in the fluid chamber 7 reaches a predetermined pressure, the rotary platen T is rotated while adjusting the air supply amount so as to maintain this pressure, and the polishing plate 1 is moved together with the rotary platen T. The slurry is supplied on the rotating platen T and mirror-finished on the wafer surface at the same time when the wafer is rotated by forced rotation or forced driving.

In this mirror finishing, compressed air is supplied from the fluid supply nozzle 4 into the fluid chamber 7 of each wafer pressurizing section 9 and is maintained at a predetermined pressure, and is uniformly spread over the entire wafer W by the elastic film 5. Therefore, even if the wafer W has uneven thickness, the elasticity of the elastic film 5 can absorb the uneven thickness. In addition, since each wafer pressing unit 9 is independent and the elastic film 5 is attached to each wafer, each wafer W is individually actuated and is suitable for a batch type. In addition, since the taper rings 6 are attached to the wafer pressurizing unit 9 to hold the periphery of the wafer W,
Lateral deflection of the wafer W can be prevented.

Furthermore, since the polishing cloth dresser 10 is provided outside the wafer pressing portion 9, the trajectory of the polishing plate 1 on the polishing cloth C is wider than the actual wafer contact portion. Therefore, it is possible to prevent a processing defect such that the outer peripheral portion of the wafer W is shaved by the edge of the deformed portion of the polishing cloth C without causing concave wear on the locus portion on the polishing cloth C.

Normally, as shown in FIGS. 6 and 7, the template 12 is placed on the lower surface of the elastic film 5 (air bag).
The wafer W is held in the circular notch 12 a formed in the template 12 and pressed by the elastic film 5, and the wafer W has an orientation flat portion W ₁ (orientation flat portion). Therefore, the orientation flat part W
The gap S ₁ between the template ₁ and the template 12 becomes larger than the gap S ₀ between the arc portion of the wafer W and the template 12, and the elastic film 5 swells at a portion where the gap is large, and the orientation flat portion W of the wafer W _{1 is} also deformed according to the bulging portion 5a. Therefore, when the wafer W is removed after the processing, the wafer W is warped.

[0019] To prevent the bulging of the elastic film 5 in the orientation flat portion W ₁ of the wafer W, the template 12
May be formed not in a circular shape but in a shape having the orientation flat portion 12b similarly to the wafer W. However, when the wafer W is pressed by the elastic film 5, the wafer W cannot be held in close contact with the
Rotates in the template 12.

In order to prevent the elastic film 5 from bulging as described above, the dimensions of the circular arc portion 12c and the orientation flat portion 12b of the template 12 must be formed to be very close to the outer diameter of the wafer W. Therefore, the template 12
When the wafer W is rotated by the inner, will interfere with the orientation flat portion 12b of the end portions and the template 12 of the orientation flat portion W ₁ of the wafer W is, as shown in FIG. 5, there is a risk of damage to the wafer W.

Accordingly, in the present invention, in order to prevent the wafer W from rotating in the template 12 as shown in FIG. 4, the cushion material 13 is interposed at the portion where the lower surface of the elastic film 5 contacts the wafer W. Let it. This cushion material 13
For example, a polishing cloth can be used, and the slip of the wafer W can be measured by avoiding direct contact between the elastic film 5 and the wafer W.

[0022]

As described above, according to the present invention,
By forming the wafer pressing portion for directly holding the wafer in the polishing plate with the elastic film forming the fluid chamber, the entire surface of the wafer is uniformly pressed by the internal pressure of the fluid chamber, and the slight Since the thickness unevenness is absorbed, highly accurate polishing can be performed. Furthermore, since a dresser for the polishing cloth is attached to the lower surface of the polishing plate, and the width of the deformed portion of the polishing cloth is wider than the actual wafer contact portion, the outer peripheral portion of the wafer does not contact the edge of the deformed portion of the polishing cloth. This makes it possible to prevent processing defects at the wafer peripheral portion. Also, a cushioning material is interposed between the lower surface of the elastic film and the contact portion between the wafer and the wafer to prevent direct contact of the wafer with the elastic film, thereby preventing rotation (slipping) of the wafer in the template, thereby preventing the wafer from rotating. Can be prevented from interfering with the orientation flat portion of the template and being damaged.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a polishing plate showing an embodiment of the present invention.

FIG. 2 is a bottom view thereof.

FIG. 3 is an explanatory diagram showing a use state.

FIG. 4 is a sectional view of a main part showing an embodiment using a template.

FIG. 5 is an explanatory diagram showing a state in which a wafer rotates within a template.

FIG. 6 is an explanatory diagram showing a relationship between an elastic film on which a template is adhered and a wafer.

FIG. 7 is a sectional view of a main part of the same.

[Explanation of symbols]

1 Polishing plate 1a Upper body 1b
Lower body 1 c O-ring 2 closed space 3 rotating main shaft 4 fluid supply nozzle 5 elastic membrane 5
a: bulging portion 6: tapering 7: fluid chamber
Reference Signs List 8: Fluid supply hole 9: Wafer pressurizing part 10: Dresser for polishing cloth 11 ... Weight 12: Template 12a notch 12b: Orientation flat part 12c ... Arc part 13: Cushion material
W: Wafer W ₁ : Orientation flat T: Rotary surface plate
C ... polishing cloth S _0, S ₁ ... interval

Continuation of the front page (51) Int.Cl. ⁷ identification code FI H01L 21/304 622 H01L 21/304 622M (58) Field surveyed (Int.Cl. ⁷ , DB name) B24B 37 / 04,37 / 00 H01L 21/304 622

Claims (3)

(57) [Claims] 1. A polishing plate of a polishing apparatus for bringing a wafer into contact with a rotating platen on which a polishing cloth is stuck, pressing the wafer against the polishing cloth with a polishing plate, and supplying a slurry to mirror-process the wafer. A closed space formed inside the polishing plate, a fluid supply nozzle for supplying and removing a fluid in the closed space, and a fluid chamber which is attached to the polishing plate by attaching an elastic film to the polishing plate, respectively. A polishing plate for pressurizing a wafer, comprising: a plurality of pressurized wafer portions provided; and fluid supply holes for communicating the individual fluid chambers and the closed space, respectively. 2. The polishing plate for pressurizing a wafer according to claim 1, wherein a dresser for polishing cloth is provided on at least the outer peripheral portion of the wafer pressing portion on the lower surface of the polishing plate. 3. A template having a notch having an arc portion and an orientation flat portion corresponding to the shape of a wafer to be processed is attached to the elastic film, and a lower surface of the elastic film is provided at a contact portion of the lower surface with the wafer. 3. The polishing plate for pressurizing a wafer according to claim 1, wherein a cushion material is interposed.