JPH0957612A - Polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly spread an abrasive solution without irregularity on the polishing surface of a material to be polished, to carry out polishing stably using a little amount of abrasive solution, lower the polishing cost, and improve effective utilization of a polishing product by enhancing the quality of the polished product. SOLUTION: The apparatus is simplified by disposing an abrasive solution supplying nozzle 8 on a retainer ring 3, while abrasive solution 9 is supplied onto a polishing cloth 6 near a material to be polished by the nozzle 8. Otherwise, the nozzle 8 is provided with a structure having an inwardly curved shape so that the abrasive solution is supplied toward the contacting surface between the polishing cloth 6 and the material 1 to be polished. Further, the material with resistance to alkaline condition is provided for the inside wall of the nozzle 8, and the number of nozzles is also selected according to the material to be polished.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polishing apparatus,
In particular, the present invention relates to a polishing device for flattening irregularities on the surface of a semiconductor substrate or the like.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing the main construction of an embodiment of a conventional polishing apparatus.

In recent years, in a semiconductor manufacturing process, a polishing apparatus for flattening irregularities of a semiconductor substrate and steps of elements and wirings has been used. The polishing process is generally a method in which the convex portions on the surface are first polished and disappeared, and then the concave portions are polished to achieve complete flattening of the surface.

In FIG. 4, a polishing material 41 such as a semiconductor wafer is fixed to a polishing material fixing block 42. The polishing material fixing block (hereinafter, simply referred to as a fixing block) 42 has a polishing material holding ring (hereinafter, a retainer ring) to prevent the polishing material 41 from being displaced from or separated from the fixing block 42 during polishing. 43) is fitted in the outer peripheral portion of the material to be polished.
On the other hand, a rotary polishing table 45 having a drive rotary shaft 44A.
A polishing cloth 46 is adhered to the upper part of the above, and a polishing liquid supply nozzle 48 is installed at the center of the polishing cloth 46.

In the conventional polishing method, the polishing liquid 4 containing the polishing material is supplied from the polishing liquid supply nozzle 48 in the above-mentioned polishing apparatus.
200 cc / min on the polishing cloth 46 that rotates with power
The polishing liquid 49 is supplied in a ratio of 1 to 3, and is diffused by the centrifugal force along the polishing cloth 46 from the central portion to the end portion of the rotary table 45. In this state, the material 41 to be polished held by the fixed block 42 is pressed against the polishing cloth 46 to perform polishing. At that time, the fixed block 42 is also rotated and swung in order to ensure the uniformity of the in-plane polishing rate of the material 41 to be polished.

[0006]

However, in the above-described conventional polishing apparatus and polishing method, since the polishing liquid 49 diffuses from the center to the outer periphery of the rotary polishing table 45 by centrifugal force, it is actually used for polishing. Polishing liquid 49
Therefore, it cannot be expected to be used efficiently. That is, since there is a distance between the material to be polished 41 and the polishing liquid supply nozzle 48, only a part of the polishing liquid 49 to be supplied reaches the material to be polished 41, and most of them is the rotary polishing table 45.
It's useless because it swings out. In particular, when the rotation speed of the rotary polishing table 45 is high, the polishing liquid 49 is scarcely used for polishing, resulting in a large amount of waste.

Therefore, when the amount of polishing liquid supplied is reduced,
When the polishing liquid 49 is insufficient between the polishing cloth 46 and the material 41 to be polished during polishing, the frictional force becomes large, and as a result, the material 41 to be polished can be disengaged from the retainer ring 43 or broken in the retainer ring 43. There is a nature. Therefore, it is necessary to flow a large amount of the polishing liquid 48 in order to perform polishing with good stability, resulting in high cost.

During polishing, the polishing liquid 49 is used as the material 4 to be polished.
Since a large amount is supplied to the peripheral portion of 1 and a small amount is supplied to the central portion, the polishing rate of the material 41 to be polished is high at the end portion and slow at the central portion (see FIG. 2 described later), and the in-plane distribution becomes nonuniform . This becomes remarkable when the diameter of the material 41 to be polished is large.

If the in-plane film thickness of the material to be polished 41 after polishing greatly varies, for example, in the case where the material to be polished 41 is an interlayer insulating film, a contact hole or a through hole is formed by a dry etching process after polishing. When opening a hole, the depth of the opening varies. As a result, there arise problems that the contact resistance or the through-hole resistance fluctuates, and that conduction between wirings cannot be established. Furthermore, variations in the interlayer insulating film adversely affect the inter-wiring capacitance, which may cause variations in the delay time between the wirings and reduce the yield.

Therefore, an object of the present invention is that the polishing liquid uniformly spreads evenly on the polishing surface of the material to be polished, and stable polishing can be performed with a small amount of polishing liquid. Therefore, the polishing cost can be reduced and the polishing product It is an object of the present invention to provide a polishing apparatus that contributes to the improvement of product utilization efficiency by improving quality.

[0011]

A polishing apparatus according to the present invention supplies a polishing liquid onto a polishing cloth attached to a rotary polishing table and holds the polishing liquid inside a material holding ring (hereinafter referred to as a retainer ring). In a polishing apparatus that presses a material to be polished onto a polishing cloth and planarly polishes the material to be polished, a polishing liquid supply nozzle is provided in a retainer ring, and the polishing liquid is supplied from the polishing liquid supply nozzle onto the polishing cloth. Is characterized by.

An inlet to the polishing liquid supply nozzle is provided on one end face in the axial direction of the retainer ring, and the shape of the nozzle is curved toward an ejection port provided on the inner end of the other end face. Is desirable. It is also preferable that the inner wall of the nozzle is made of a material that withstands a polishing liquid having an alkalinity of Ph10-11. Furthermore, it is more desirable that the plurality of nozzles are arranged at substantially equal intervals on one circumference centered on the axis of the retainer ring.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a sectional view showing the main structure of an embodiment of a polishing apparatus of the present invention, FIG. 1B is a plane sectional view taken along the line BB of FIG. 1A, and FIG. 3A is a partially enlarged cross-sectional view of FIG. 2A, FIG. 2 is a diagram showing the in-plane distribution of the polishing rate in the present embodiment and the conventional example, and FIG. Is a cross-sectional view showing (a), (b) is (a)
FIG. 6B is a cross-sectional view after the polishing step according to the present embodiment.

As shown in FIG. 1, a plurality of polishing liquid supply nozzles 8 are provided in a retainer ring 3 which is integrated with a polishing material fixing block (hereinafter, simply referred to as a fixing block) 2 for fixing a polishing material 1. Is provided. Further, a polishing liquid supply passage 7 penetrates through the center of a rotary shaft 4B connected to the fixed block 2, and the polishing liquid supply passage 7 is connected to a flow control valve (not shown) and a polishing liquid pressure pump in this order. It is connected.

Similarly to the fixed block 2, the rotary polishing table 5 has a rotary shaft 4A, and a polishing cloth 6 made of a porous curable polyurethane foam resin is attached to the upper portion of the rotary polishing table 5 with an adhesive tape. ing.

The polishing apparatus of the present invention comprises a rotary polishing table 5
In a polishing apparatus for supplying a polishing liquid 9 onto a polishing cloth 6 attached to the upper surface of the polishing cloth 6 and pressing the material to be polished 1 held in a retainer ring 3 to the polishing cloth 6 to polish the material to be polished 1 into a flat surface, The polishing liquid supply nozzle 8 is provided in the retainer ring 3, and the polishing liquid 9 is supplied from the polishing liquid supply nozzle 8 onto the polishing cloth 6.

The inlet to the polishing liquid supply nozzle 8 is
The nozzle 8 is provided on the upper end surface in the axial direction of the retainer ring 3, and the shape of the nozzle 8 is curved toward the ejection port provided on the inner end of the lower end surface. The inner wall of the nozzle 8 is Ph
It is made of a material that withstands the polishing liquid 9 having an alkalinity of 10 to 11. In addition, a plurality of (eight in the illustrated case) nozzles 8 are provided at substantially equal intervals on one circumference around the axis of the retainer ring. The number of the nozzles is appropriately selected according to the size of the material to be polished.

Next, the operation of the polishing apparatus according to this embodiment will be described. Although the vacuum suction system is not shown in the fixed block 2 in FIG. 1, first, the material to be polished 1 is fixed in the retainer ring 3 by vacuum suction, and the material to be polished 1 is not landed on the rotary polishing table 5. While rotating the rotary polishing table 5, the polishing liquid 9 is caused to flow from the polishing liquid supply nozzle 8. The polishing liquid 9 is an alkaline aqueous solution (for example, potassium hydroxide, ammonium hydroxide, sodium hydroxide, organic amine, etc.) having a pH of 10 to 11 and containing silicon dioxide (SiO ₂ ) having an average particle diameter of 20 nm, and is fixed by a boost pump. From the polishing liquid supply nozzle 8 provided in the retainer ring 3 via the polishing liquid supply passage 7 in the block 2 to the polishing cloth 6
Pour on. In this retainer ring 3, the nozzle 8
As described above, since the flow path toward the ejection port of No. 1 is curved toward the inner end of the lower end surface, the polishing liquid 9 is ejected in the direction of the material to be polished 1 according to the flow path, and the material to be polished 1 and the polishing material 1 are polished. Cloth 6
The ratio actually used at the contact surface with is increased. Therefore, the amount of the polishing liquid 9 used can be small. The flow rate of the polishing liquid 9 is 100 cc / min and is controlled by the flow rate control valve. Also, the rotary polishing table 5 is 30 rp
Rotate at m.

While the polishing liquid 9 is sufficiently dispersed on the polishing cloth 6, the fixed block 2 is rotated at 30 rpm to land the material 1 to be polished on the polishing cloth 6, and a pressure is gradually applied to the fixed block 2 to apply the material to be ground. The polishing material 1 is polished.

FIG. 2 shows the in-plane distribution of the polishing rate of the material to be polished 1 in the present embodiment until the end of polishing, as compared with that in the conventional example. In the present invention, as indicated by the line C in the figure, the difference in the polishing rate between the central portion and the end portion of the material to be polished 1 is 0.01 μm, and the variation in the polishing rate compared to the line D in the prior art. Was reduced to about 1/5, and it became possible to obtain good in-plane uniformity.

In addition, the polishing liquid supply nozzle 8 is provided in the retainer ring 3 as described above, so that the entire apparatus can be simplified.

[0023]

As described above, the present invention has a structure in which the polishing liquid supply nozzle is provided in the retainer ring and the polishing liquid is directly supplied to the material to be polished. Along with the simplification of the entire apparatus, it is possible to remarkably utilize the polishing liquid, and therefore, without causing excessive flow of the polishing liquid, there is no fear of a shortage of the polishing liquid between the polishing cloth and the material to be polished and a frictional adverse effect thereof, and as a result, Since the polishing liquid uniformly spreads evenly on the polishing surface and stable polishing can be performed, there is an effect that it is possible to provide a polishing apparatus capable of manufacturing a product of high quality, that is, a high yield, at low cost.

[Brief description of drawings]

1A is a cross-sectional view showing a main configuration of an embodiment of a polishing apparatus of the present invention, FIG. 1B is a plane cross-sectional view taken along line BB of FIG. 1A, and FIG. It is a partial expanded sectional view of a).

FIG. 2 is a diagram showing an in-plane distribution of a polishing rate in the present embodiment and a conventional example.

FIG. 3A is a sectional view showing a concavo-convex state of a material to be polished before a polishing step, and FIG. 3B is a sectional view after a polishing step according to the present embodiment of FIG.

FIG. 4 is a sectional view showing a main configuration of an embodiment of a conventional polishing apparatus.

[Explanation of symbols]

1,41 Polishing material 2,42 Polishing material fixing block 3,43 Retainer ring (polishing material retaining ring) 4A, 4B, 44A, 44B Rotating shaft 5,45 Rotating polishing table 6,46 Polishing cloth 7,47 Polishing Liquid supply path 8,48 Polishing liquid supply nozzle 9,49 Polishing liquid 21 Semiconductor substrate 22 Insulating film 23 Al wiring 24 Plasma oxide film

Claims (4)

[Claims] 1. A polishing liquid is supplied onto a polishing cloth attached on a rotary polishing table, and the polishing material held inside a polishing material holding ring is pressed against the polishing cloth to flatten the polishing material. In a polishing device for polishing, a polishing liquid supply nozzle is provided in the material to be polished holding ring, and the polishing liquid is supplied from the polishing liquid supply nozzle onto the polishing cloth. 2. An inflow port to the polishing liquid supply nozzle is provided on one end face in the axial direction of the polishing target material holding ring, and the shape of the nozzle is directed to an ejection port provided on the inner end of the other end face. The polishing apparatus according to claim 1, wherein the polishing apparatus is curved. 3. The nozzle has an inner wall of Ph10-11.
The polishing apparatus according to claim 1, which is made of a material that withstands the polishing liquid having the alkalinity. 4. The polishing apparatus according to claim 1, wherein the plurality of nozzles are arranged at substantially equal intervals on one circumference centered on the axis of the retaining ring.