JP2708022B2 - Polishing equipment - Google Patents

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 apparatus for flattening irregularities on a surface of a semiconductor substrate or the like.

[0002]

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

In recent years, in a semiconductor manufacturing process, a polishing apparatus for flattening unevenness of a semiconductor substrate and steps of elements and wiring has been used. Generally, the polishing process is a method in which convex portions on the surface are first polished and disappeared, and then the concave portions are polished, whereby the surface is completely flattened.

In FIG. 4, a material 41 to be polished, such as a semiconductor wafer, is fixed to a material fixing block 42. A material-to-be-polished fixed block (hereinafter, simply referred to as a fixed block) 42 includes a material-to-be-polished holding ring (hereinafter, referred to as a retainer ring) for preventing the material to be polished 41 from shifting or coming off from the fixed block 42 during polishing. 43 is fitted on 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 an upper portion of the polishing pad 46, and a polishing liquid supply nozzle 48 is provided at a central portion on the polishing cloth 46.

In the conventional polishing method, in the above-described polishing apparatus, the polishing liquid 4 containing an abrasive is supplied from a polishing liquid supply nozzle 48.
9 is 200 cc / min on the polishing cloth 46 which rotates by power.
And the polishing liquid 49 is diffused by the centrifugal force along the polishing cloth 46 from the center to the end of the turntable 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 this time, the fixed block 42 is also rotated and oscillated in order to ensure 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, the polishing liquid 49 is diffused from the center to the outer periphery of the rotary polishing table 45 by centrifugal force, so that it is actually used for polishing. Polishing liquid 49
Is low and therefore cannot be expected to be used efficiently. That is, since there is a distance between the polishing target material 41 and the polishing liquid supply nozzle 48, only a part of the polishing liquid 49 to be supplied reaches the polishing target material 41, and most of the polishing liquid 49 is supplied to the rotary polishing table 45.
It is wasted because it swings out. In particular, when the rotation speed of the rotary polishing table 45 is high, the polishing liquid 49 is hardly used for polishing, and waste is increased.

Therefore, when the supply amount of the polishing liquid is reduced,
If the polishing liquid 49 runs short between the polishing pad 46 and the polishing target material 41 during polishing, the frictional force increases, and as a result, the polishing target material 41 may come off the retainer ring 43 or break in the retainer ring 43. There is. Therefore, a large amount of the polishing liquid 48 must be flowed in order to perform polishing with high stability, resulting in an increase in cost.

During polishing, the polishing liquid 49 is applied to the material 4 to be polished.
1, the polishing rate of the material 41 to be polished is high at the end and low at the center (see FIG. 2 described later), and the in-plane distribution becomes non-uniform. . This becomes remarkable when the diameter of the material to be polished 41 is large.

If the in-plane film thickness of the polished material 41 varies greatly after polishing, for example, when the polished material 41 is an interlayer insulating film, a contact hole or a through hole is formed using a dry etching process after polishing. When a hole is formed, the depth of the hole varies. As a result, there arises a problem that the contact resistance or the through-hole resistance varies and the wiring cannot be conducted. Further, variations in the interlayer insulating film have an adverse effect on the capacitance between wirings, and may cause variations in delay time between wirings, which may lower the yield.

Accordingly, an object of the present invention is to provide a polishing liquid which is evenly and evenly spread on a polished surface of a material to be polished, and can perform stable polishing with a small amount of polishing liquid. An object of the present invention is to provide a polishing apparatus that contributes to an improvement in product utilization efficiency by improving quality.

[0011]

A polishing apparatus according to the present invention supplies a polishing liquid onto a polishing cloth stuck on a rotary polishing table and is held inside a material holding ring (hereinafter referred to as a retainer ring). A polishing liquid supply nozzle is provided on a retainer ring, and the polishing liquid is supplied onto the polishing cloth from the polishing liquid supply nozzle in a polishing apparatus for planarly polishing the material to be polished by pressing the material to be polished against the polishing cloth. It is characterized by.

An inlet to the polishing liquid supply nozzle is provided at one end face in the axial direction of the retainer ring, and the shape of the nozzle is curved toward an ejection port provided at an inner end of the other end face. It is desirable. In addition, it is desirable that the inner wall of the nozzle is made of a material that can withstand a polishing liquid having an alkalinity of Ph10 to Ph11. Further, it is more preferable 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 a main structure of an embodiment of a polishing apparatus according to the present invention, FIG. 1B is a plan sectional view taken along line BB of FIG. 1A, and FIG. , (A) is a partially enlarged cross-sectional view, FIG. 2 is a view showing an in-plane distribution of a polishing rate in the present embodiment and a conventional example, and FIG. 3 (a) is an unevenness state of a material to be polished before a polishing step. (B) is a sectional view showing (a).
FIG. 4 is a cross-sectional view after a polishing step according to the present embodiment.

As shown in FIG. 1, a plurality of polishing liquid supply nozzles 8 are provided on a retainer ring 3 integrated with a material-fixing block (hereinafter, simply referred to as a fixing block) 2 for fixing the material 1 to be polished. Is provided. A polishing liquid supply path 7 penetrates the center of the rotating shaft 4B connected to the fixed block 2, and the polishing liquid supply path 7 is connected to a flow rate control valve (not shown) and a polishing liquid pressure pump in this order. Are linked.

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 hardening foamed polyurethane resin is adhered 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, a polishing liquid 9 is supplied onto a polishing cloth 6 stuck thereon, and a material 1 to be polished held in a retainer ring 3 is pressed against the polishing cloth 6 to planarly polish the material 1 to be polished. The polishing liquid supply nozzle 8 is provided on the retainer ring 3, and the polishing liquid 9 is supplied from the polishing liquid supply nozzle 8 onto the polishing pad 6.

The inlet to the polishing liquid supply nozzle 8 is
The nozzle 8 is provided on the upper end face 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 face. The nozzle 8 has an inner wall of Ph
It is made of a material that can withstand 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 a circle around the axis of the retainer ring. The number of nozzles is appropriately selected according to the size of the material to be polished.

Next, the operation of the polishing apparatus according to the present embodiment will be described. Although a vacuum suction system is not shown in the fixed block 2 in FIG. 1, first, the material 1 to be polished is fixed in the retainer ring 3 by vacuum suction, and the material 1 to be polished is not landed on the rotary polishing table 5. The polishing liquid 9 flows from the polishing liquid supply nozzle 8 while rotating the rotary polishing table 5. The polishing liquid 9 is an aqueous solution of an alkaline system (for example, potassium hydroxide, ammonium hydroxide, sodium hydroxide, organic amine, or the like) having a pH of 10 to 11 containing silicon dioxide (SiO ₂ ) having an average particle diameter of 20 nm, and fixed by a pressure pump. A polishing cloth 6 is supplied from a polishing liquid supply nozzle 8 provided on the retainer ring 3 via a polishing liquid supply path 7 in the block 2.
Pour over The nozzle 8 in the retainer ring 3
As described above, the flow path toward the spout is curved toward the inner end of the lower end surface, so that the polishing liquid 9 is jetted in the direction of the material 1 to be polished in accordance with the flow path, and Cloth 6
The ratio actually used on the contact surface with the metal is increased. Therefore, the amount of the polishing liquid 9 used is small. The flow rate of the polishing liquid 9 is 100 cc / min, and is controlled by a flow control valve. In addition, the rotary polishing table 5 has a rotation speed of 30 rpm.
Rotate at m.

With the polishing liquid 9 sufficiently diffused on the polishing cloth 6, the material 1 to be polished lands on the polishing cloth 6 while rotating the fixed block 2 at 30 rpm. The polishing material 1 is polished.

FIG. 2 shows the in-plane distribution of the polishing rate of the material 1 to be polished up to the end of polishing in this embodiment in comparison with that in the conventional example. In the present invention, as shown by the line C in the figure, the difference in the polishing rate between the center and the end of the material to be polished 1 is 0.01 μm. Was reduced to about 1/5, and good in-plane uniformity could be obtained.

Further, as described above, the structure of the polishing liquid supply nozzle 8 provided in the retainer ring 3 can simplify the entire apparatus.

[0023]

As described above, according to the present invention, the polishing liquid supply nozzle is provided on the retainer ring, and the polishing liquid is directly supplied toward the material to be polished. Along with the simplification of the entire apparatus, the polishing liquid can be remarkably effectively used, and therefore, there is no danger of lack of the polishing liquid between the polishing cloth and the material to be polished without flowing the polishing liquid excessively and the adverse effect of friction. Since the polishing liquid is evenly spread on the polishing surface and stable polishing can be performed, there is an effect that a polishing apparatus capable of producing a high quality product with a good use yield at low cost can be provided.

[Brief description of the drawings]

1A is a cross-sectional view showing a main configuration of an embodiment of a polishing apparatus according to the present invention, FIG. 1B is a cross-sectional plan 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 cross-sectional view illustrating a state of unevenness of a material to be polished before a polishing step, and FIG. 3B is a cross-sectional view after the polishing step according to the present embodiment in FIG.

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

[Explanation of symbols]

1,41 Material to be polished 2,42 Block for fixing material to be polished 3,43 Retainer ring (Ring for holding material to be polished) 4A, 4B, 44A, 44B Rotary shaft 5,45 Rotary 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)

(57) [Claims] 1. A polishing liquid is supplied onto a polishing cloth stuck on a rotary polishing table, and a material to be polished held inside a material to be polished holding ring is pressed against said polishing cloth to flatten the material to be polished. In a polishing apparatus for polishing, a polishing liquid supply nozzle is provided on the material holding ring, and the polishing liquid is supplied from the polishing liquid supply nozzle onto the polishing cloth. 2. An inflow port for the polishing liquid supply nozzle is provided at one axial end surface of the material holding ring to be polished, and the shape of the nozzle is directed toward a spout provided at an inner end of substantially the other end surface. The polishing apparatus according to claim 1, wherein the polishing apparatus is curved. 3. The nozzle has an inner wall having a thickness of Ph10-11.
The polishing apparatus according to claim 1, wherein the polishing apparatus is made of a material that can withstand a polishing liquid having an 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 holding ring.