JP3179064B2 - Slurry supply equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical mechanical device used for flattening an interlayer insulating film, forming a metal plug, and forming a buried metal wiring required for forming a multilayered metal wiring structure of an LSI. The present invention relates to an apparatus for supplying a slurry (abrasive) supplied to a wafer polishing apparatus by a mechanical polishing (chemical mechanical polishing, hereinafter abbreviated as CMP) method.

[0002]

2. Description of the Related Art In recent years, CMP has attracted attention as a fine processing technique for achieving high integration and high performance of LSI. This CMP involves a chemical action between the slurry and the object to be polished,
This is a polishing technique that combines the mechanical action of the abrasive grains in the slurry with the property that the altered layer formed on the surface to be polished is small and has a high polishing rate. It is an important technique for flattening an interlayer insulating film, forming metal plugs, and embedding metal wiring in a wiring forming process.

As a polishing apparatus used in the CMP, a disk-shaped polishing platen having a polishing cloth adhered to a surface thereof, and one surface of a wafer to be polished is held, and the other surface of the wafer is brought into contact with the polishing cloth. A plurality of wafer holding heads, and a head drive mechanism for rotating these wafer holding heads relative to a polishing platen, and performing polishing by supplying a slurry containing abrasive grains between a polishing cloth and a wafer. Things are conventionally known.

A mechanism shown in FIG. 3 has been conventionally used as a slurry supply mechanism. That is, silica,
Abrasive grains A, such as alumina, zirconia, manganese dioxide, and ceria, and an additive solution B of an oxidizing agent, such as hydrogen peroxide, or an alkaline agent, such as ammonia, are put into a tank 1 at a predetermined mixing ratio and stirred and mixed. A slurry (abrasive) is generated, supplied to the supply tank 2 and temporarily stored therein, and the pump P is operated as appropriate to inject the slurry from the nozzle 4 onto the polishing platen 3.

[0005]

In such a conventional slurry supply mechanism, since the formed slurry is temporarily stored in the supply tank 2, the reaction is accelerated in the tank and the characteristics of the slurry are increased. In the worst case, the slurry must be discarded. Further, depending on the object to be polished, it is necessary to change the content of the slurry and its mixing ratio, but since the slurry is temporarily stored in the supply tank 2, the mixing ratio cannot be changed immediately before use. In addition, there has been a problem that the state of polishing cannot be monitored and the result cannot be fed back.

Accordingly, the present invention has been made in view of the above-mentioned problems, and it is possible to generate a slurry immediately before a polishing operation.
It is an object of the present invention to provide a slurry supply apparatus that can control the mixing ratio of the slurry easily and freely without waste of the slurry and can easily reflect the result of the polishing state.
Further, according to the present invention, a mixing vessel, which is conventionally required, is not required, and a slurry supply device having good dispersibility of abrasive grains can be obtained.

[0007]

According to the present invention, there is provided a slurry supply apparatus as described in the claims as means for solving the above-mentioned problems. The slurry supply device according to claim 1 combines the aqueous abrasive solution and the additive solution supplied from the respective tanks and mixes them immediately before spraying to the polishing platen, thereby promoting the reaction of the slurry. It is possible to supply a slurry having a certain characteristic without causing the problem. This also eliminates the need for a mixing vessel and prevents the reaction from proceeding excessively and discarding the slurry. Change
Dispersion of abrasive powder by installing an ultrasonic device in the mixer
To obtain a uniformly mixed slurry.
it can.

[0008] The slurry supply apparatus according to the second aspect,
Mix the aqueous abrasive solution and the additive solution, which are provided just before the polishing platen.
By controlling the temperature of the slurry by providing an electric heater in the mixing mixer, the reaction of the slurry can be promoted (the reaction may not be promoted too much), and the management of the slurry is easy.

[0009] The slurry supply apparatus according to claim 3 is
Electric heater and supersonic
By providing both wave devices, mixing uniformity and slurry
-Temperature can be controlled and the quality of slurry can be kept constant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A slurry supply apparatus according to an embodiment of the present invention will be described below. FIG. 1 is a circuit diagram of a slurry supply device according to an embodiment of the present invention. 10
Is a tank containing an aqueous solution A containing abrasive grains such as silica, ceria, and alumina, and 11 is an additive solution B of an acidic agent such as hydrogen peroxide or an alkaline agent such as ammonia.
It is a tank containing. Reference numeral 17 denotes a pump P, for example, using a diaphragm pump.

The aqueous solution A of the abrasive grains is supplied from the tank 10 by a pump P17 and sent through a solenoid valve 13, a constant flow valve 12 and an orifice 15, and similarly from the tank 11 to a pump P17, a solenoid valve 13 and a constant flow. It merges with the additive solution B sent through the valve 12 and the orifice 15, enters the mixer just before being supplied to the polishing platen 22, and is mixed into a slurry (abrasive). It is sprayed on the board 22. Since the aqueous solution A of the abrasive grains and the additive solution B are sent at almost the same pressure, they do not merge well and do not flow backward. Reference numeral 18 denotes a flow meter for monitoring, from which a flow signal is sent to a controller 19, and the signal from the controller 19 is converted to air pressure by a converter 16 to control the constant flow valve 12. Reference numeral 20 denotes a valve provided in the return circuit, which controls the pressure in the circuit. The diameter of the orifice 15 is different between the aqueous solution side and the additive solution side of the abrasive grains, and is about φ1.0 on the abrasive grain side and about 1/5 of the diameter on the additive solution side.

In the embodiment shown in FIG. 1, the structure of the mixer 14 is such that a twisted plate is inserted in the tube.
A structure in which a baffle plate is provided in the tube may be used.
Any structure may be adopted as long as the components are sufficiently stirred and mixed. Further, an electric heater 24 is wound around the mixer 14 and an ultrasonic device 23 is provided. When the two solutions are too low in temperature to perform a sufficient reaction, the electric heater 24 can be heated to accelerate the reaction. By operating the ultrasonic device 23, the dispersibility of the abrasive grains is improved, and the abrasive grains are more uniformly mixed.

Although not shown in FIG. 1, a monitor for monitoring the polishing condition is arranged near the polishing platen 22, and information from this monitor is input to the controller 19, from which a converter is provided. By sending a signal to 16 and controlling the constant flow valve 12, the mixing ratio between the aqueous solution of abrasive grains and the additive solution can be easily changed according to the polishing situation. After the polishing is completed, a cleaning liquid is supplied from a backwash valve (not shown) provided between the constant flow valve 12 and the solenoid valve 13 to clean the piping system.

FIG. 2 is a circuit diagram of a slurry supply apparatus according to another embodiment of the present invention. The slurry supply device further includes a tank 10a for an aqueous solution C of abrasive grains different from the aqueous solution A of abrasive grains contained in the tank 10, and a means for supplying the aqueous solution C is provided in parallel. . In this supply means, the same components as those used in the above-described supply means are used in the same arrangement. By doing so, a slurry of the solutions A and B and a slurry of the solutions C and B can be formed, and can be supplied to different polishing plates 22, respectively, so that the slurry can be selected according to the polishing object. . It should be noted that it is possible to provide a supply system for aqueous solutions of many different types of abrasive grains, and it is also possible to add a supply system for a plurality of types of additive solutions with respect to the additive solution. Various types of slurries can be generated, and it can respond to diversification of polishing.

Further, in FIG. 2, two systems for supplying the aqueous solution A of the abrasive grains are arranged in parallel, so that even if a trouble occurs in one system, the other system can be used. It is also possible to use a slurry with a different mixing ratio in another system.

[0016]

As described above, since the slurry supply apparatus of the present invention mixes the abrasive grains and the additives immediately before supplying them to the polishing platen, the slurry is separated by the lapse of time after the mixing. The slurry can be supplied in a completely mixed state without being mixed, and the modification of the slurry due to the progress of the reaction due to the storage of the mixed slurry can be prevented. Also, the mixing ratio of the slurry can be freely controlled, and the mixing ratio of the slurry can be changed according to the polishing condition, or another slurry can be used.
Can cope with diversification of polishing. Further, there are many advantages such that the dispersibility of the abrasive grains can be improved by ultrasonic waves and uniform mixing can be performed, and the reaction can be controlled by controlling the temperature of the slurry by an electric heater.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a slurry supply device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a slurry supply device according to another embodiment of the present invention.

FIG. 3 is a schematic explanatory view of a conventional slurry supply device.

[Explanation of symbols]

 10, 10a, 11 ... tank 12 ... constant flow valve 14 ... mixer 15 ... orifice 18 ... monitor flow meter 19 ... controller 21 ... nozzle 22 ... polishing platen 23 ... ultrasonic device 24 ... electric heater

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B24B 57/02 B24B 37/00

Claims (3)

(57) [Claims] 1. A slurry supply device for supplying a slurry to a wafer polishing apparatus by a chemical mechanical polishing method, comprising: an abrasive aqueous solution supply means for supplying an aqueous solution of the abrasive through a constant flow valve and an orifice; It has additive solution supply means for supplying from a tank of the additive solution such as hydrogen through a constant flow valve and an orifice, and the abrasive aqueous solution and the additive solution supplied from the respective supply means are merged to form a polishing platen. Immediately before injection, ultrasonic device
Wherein the two solutions are mixed into a slurry by a mixer provided with the slurry. 2. A wafer polishing apparatus using a chemical mechanical polishing method.
In the supply device for the slurry supplied to the device, the aqueous solution of the abrasive is transferred from the tank through the constant flow valve and the orifice.
A constant flow rate valve and an orifice
And an additive solution supply means for supplying the aqueous solution of abrasive grains and the additive solution supplied from the respective supply means.
And the electric heater just before spraying to the polishing platen
The two solutions are mixed by a mixer provided with
And the temperature of the slurry is controlled.
Slurry supply device. 3. An ultrasonic device is further provided in said mixer.
The slurry supply device according to claim 2, wherein: