KR20000059169A - System for suplying slurry in the CPM process of semiconductor manufacturing - Google Patents

Abstract

PURPOSE: A system for supplying a slurry in a CMP(chemical mechanical polishing) process is to smoothly circulate the slurry and simultaneously supply the slurry to each position equally, thereby increasing a yield of a semiconductor. CONSTITUTION: A system for supplying a slurry in a CMP(chemical mechanical polishing) process comprises a main hydraulic circuit(8') comprised of a withdrawing pipe(14') and a supplying pipe(12') connected to a supplying portion(4) to circulate the slurry, a flow meter(34) and a pressure gage(30) for measuring a flow and a pressure in a slurry supplying line, and an automatic valve(34) for automatically opening/closing the hydraulic circuit according to the flow and pressure measured in the flow meter and pressure gage. In the system, a pressure difference between the supplying pipe and the withdrawing pipe is equally maintained.

Description

System for suplying slurry in the CPM process of semiconductor manufacturing}

The present invention relates to a semiconductor CMP process, and more particularly to a slurry supply system of a semiconductor CMP process for supplying a certain amount of slurry to each point of use (POU) to which the slurry is supplied.

CMP (Chemical Mechanical Polishing) technology, which can be interpreted as a chemical / physical polishing process in semiconductors, is one of the techniques for planarizing the surface of a wafer. In more detail, a polishing pad is brought into contact with a thin film surface on which a wafer pattern is formed, and then rotated and polished while supplying a slurry liquid of suspension form to the surface. The wafer surface is chemically and physically processed. Flat processing technology.

This technology is a technology developed according to the necessary requirements due to the high integration and complexity of the surface structure of the semiconductor device, various processing methods and cleaning liquids (slurry) has been developed.

Here, silica is generally used as a chemical currently used as a slurry, and other nitric acid solutions, potassium hydroxide, OXIDE, POLY, or METAL have been variously developed and used.

The present invention relates, in particular, to an improvement of the above slurry solution supply system, and is intended to solve various problems of the conventional slurry supply system shown in FIG.

A conventional slurry supply system will be described below with reference to FIG. 1.

The slurry withdrawn from the source drum (2, Source Drum) containing the slurry stock solution and supplied to the supply unit 4 is passed through the supply pipe in a state in which pressure is applied by a hydraulic pump (not shown) to the respective point of use (6, POU, Point of use). Points of use can be provided in various numbers, from one to thirteen depending on the size of the installation.

As shown, the slurry is circulated along the main hydraulic circuit 8, which is composed of the supply pipe 12 and the recovery pipe 14, some of which branch off from the supply pipe to connect to the recovery pipe through the point of use. Be passed through a plurality of sub-hydraulic circuit (10). The slurry is supplied to the surface of the wafer while passing through the sub hydraulic circuit.

The slurry recovered through the recovery pipe 14 and the recovery pipe 16 of the sub-hydraulic circuit is returned and stored in the temporary storage tank 18, and then returned to the supply unit 4 to be recycled.

The conventional method for supplying the slurry to the point of use in the required amount at the required time is to install the valves 22 in the supply pipe 20 and the recovery pipe 16 of the sub hydraulic circuit, respectively. The valve 22 is an electronic manual valve, and a method of opening and closing the valve 22 is used. In addition, an end reducer 24 of the recovery pipe 14 is provided. The reducer 24 is used in order to maintain the pressure of the hydraulic circuit to a certain degree by reducing the inner diameter like the venturi tube.

The slurry is only supplied when the operator closes the switch, so that its flow rate is controlled only by time. That is, regardless of the hydraulic pressure of the main circuit 8 and the sub-circuit 10, since the flow rate is supplied only by opening and closing the valve 22, it was difficult to expect a constant flow rate supply to all the use points (6), respectively.

The biggest problem in the conventional system is that due to the decrease in the back pressure at the end of the return pipe 14 of the main circuit, an appropriate amount of slurry cannot be supplied to the point of use 6 through the sub circuit 10. It is. This slowed down the circulation of the slurry in the subcircuits and resulted in precipitation and aggregation of the slurry. In-circuit precipitation of the slurry and coagulation between particles cause further unstable flow rate and lower the specific gravity of the slurry (the fine particles constituting the slurry coagulate with each other by ionic action when a smooth circulation is not achieved. ). The lowering of the flow rate of the slurry is a cause of lowering the chemical effect in the CMP technology, and the aggregated slurry particles generate fine scratches on the surface of the wafer, thereby damaging the wafer and lowering the yield.

An object of the present invention for the above problems is to improve the yield of the semiconductor by providing a slurry supply system to facilitate the circulation of the slurry and to be supplied at a constant flow rate to each point of use. For this system, the present invention has a specific purpose to automatically supply a constant flow rate at a point of use by automatically controlling the hydraulic pressure in the circuit.

1 shows a conventional slurry supply system.

2 is a block diagram of a slurry supply system according to the present invention.

3 is a block diagram of a slurry supply system according to another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

2 ; Source drum 4; Supply department

6; Point of use 8,8 '; Main circuit

10,10 '; Sub circuit

The above object is to provide a slurry supply system in a CMP process for polishing a surface of a semiconductor wafer, comprising a supply pipe and a recovery pipe connected to a supply tank to circulate the slurry. A hydraulic circuit; Slurry supply line composed of a plurality of sub hydraulic circuits, one end of which is connected from the supply pipe and the other end of which is connected to the recovery pipe, for drawing and supplying a part of the flow rate of the circulated slurry to the point of use, that is, the polishing part of the wafer. A pressure gauge for checking the pressure; It is achieved by the slurry supply system of the semiconductor CMP process, characterized in that an automatic valve for automatically opening and closing the hydraulic circuit in accordance with the checked pressure.

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

2 is a block diagram of a slurry supply system according to an embodiment of the present invention.

The basic circuit configuration for the supply of the slurry is the same as that of the conventional one and will be briefly described. A main hydraulic circuit 8 '(hereinafter, referred to as a main circuit) composed of a supply pipe 12' and a recovery pipe 14 'is connected from a supply part 4 including a supply tank, a pump, and the like. A plurality of sub hydraulic circuits 10 ′ (hereinafter, sub circuits) are connected to various parts of the supply pipe. One end of the sub circuit is connected to the supply pipe 12 'and the other end is connected to the recovery pipe 14'. The intermediate point of the sub-circuit is connected to the point of use 6, i.e., to the polishing section (part composed of the polishing pad, wafer, slurry supply stage, etc.). The slurry is withdrawn and supplied through this pipe. The remaining slurry that is not withdrawn is returned to the storage tank 4 through the recovery pipe 14 '. Here, the main circuit 8 'is connected by a pipe having a diameter larger than that of the sub circuit 10'.

The slurry is flowed in the direction of the arrow shown by the above circuit configuration.

According to the embodiment of the present invention, a pressure gauge 30 for checking the pressure of the flow rate flowing in the main circuit 8 ', and an automatic valve 32 which is automatically opened and closed in accordance with the pressure measured by the pressure gauge are provided in the supply pipe ( 12 ') and the recovery pipe 14'. In addition, a flow meter 34 for measuring the flow rate may be further installed. By such a hydraulic device, the valve 32 operates like a constant pressure valve for maintaining the pressure in the circuit at a constant level.

The operating state of the system by such a configuration is as follows. When the pressure difference between the recovery pipe 14 'and the supply pipe 12' (exactly, the inlet pressure of the supply pipe and the outlet pressure difference of the recovery pipe) becomes larger than the set value, the valve 32 automatically By closing, it is possible to prevent a decrease in the flow rate supplied to the point of use. In addition, when the pressure in the recovery pipe 14 'becomes too high, the valve 32 is automatically opened, thereby preventing the excess flow rate at the point of use 6 from being drawn out. The valve 32 used herein is a type capable of adjusting the opening and closing amount, and is required to have a type capable of precisely controlling the flow rate.

Opening and closing of the valve 32 may be controlled by receiving a signal from the flow meter 34. In other words, if the flow rate of the recovered slurry is too large, the flow rate toward the point of use is increased by closing the valve and decreasing the flow rate.

It will be apparent to those skilled in the art that such a flow control mechanism may be installed at the end 14'a of the recovery pipe because the purpose of the flow control mechanism is to control the pressure applied to the end of the recovery pipe.

On the other hand, a three-way valve (33, 3-way valve) is provided between the main circuit and the sub-circuit, so that the circuit can be driven even when there is an abnormality in the control section (30, 32, 34).

According to another embodiment of the present invention, a system is provided that allows for finer control of the slurry flow rate. 3 is a configuration diagram of a subcircuit according to another exemplary embodiment of the present invention.

The supply pipe and the recovery pipe of each subcircuit are provided with a measuring device 36 for measuring the pressure or flow rate and an automatic valve 38 which is opened and closed in accordance with the measurement result. The type of the valve 38 used in this embodiment is a flow control valve suitable for the pipe connection structure as shown.

In addition, since the flow rate adjustment by opening and closing the valve has its limit, it is provided with a pressure adjusting means 40 capable of raising or lowering the supply tank. That is, the capacity of the nitrogen (N ₂ ) filling pressure of the supply tank is adjusted in a feedback manner based on the flow rate supplied to the point of use.

To this end, the supply unit 4 includes a nitrogen tank 42, a flow control valve 44 connected therefrom, a slurry supply tank 46 connected to a point of use, and a recovery tank connected to an end of the recovery pipe ( 48). The flow rate or pressure value measured by the crab side of the main circuit acts as a variable for adjusting the flow control valve 44, and the supply amount of nitrogen changes according to the opening and closing degree of the flow control valve. The supply amount or supply pressure of nitrogen is proportional to the flow rate or pressure for extruding the slurry from the supply tank to the main circuit.

This is a type suitable for optimal control of the amount of slurry recovered and the amount of slurry directed to the point of use.

As mentioned above, this invention makes it the summary to check and adjust automatically the pressure or flow volume in a slurry supply circuit. Therefore, other modified embodiments of the above spirit will be within the scope of the technical idea of the present invention.

By the above pressure to flow control system, the slurry is smoothly circulated in the circuit to minimize the amount of flocculation. In addition, the slurry can be supplied to each point of use in the required amount to maximize the effect of the semiconductor CMP (CMP) process to bring the improved yield of the wafer.

Claims (3)

In a slurry supply system in a CMP process for polishing a surface of a semiconductor wafer, the slurry is circulated by a supply pipe 12 ′ and a recovery pipe 14 ′ connected to the supply unit 4. A main hydraulic circuit 8 '; A plurality of sub-hydraulic circuits 10 'for drawing and supplying some of the flow rate of the circulated slurry to the point of use 6, that is, the polishing portion of the wafer, one end of which is connected from the supply pipe and the other end of which is connected to the recovery pipe In the slurry supply line consisting of a), by installing a flow meter 34 for checking the flow rate and pressure and an automatic valve 34 for automatically opening and closing the hydraulic circuit in accordance with the flow rate and pressure measured by the pressure gauge 30; Slurry supply system of the semiconductor CMP process, characterized in that to maintain a constant pressure difference between the supply pipe (12 ') and the recovery pipe (8'). In a slurry supply system in a CMP process for polishing a surface of a semiconductor wafer, the slurry is circulated by a supply pipe 12 ′ and a recovery pipe 14 ′ connected to the supply unit 4. A main hydraulic circuit 8 '; A plurality of sub-hydraulic circuits 10 'for drawing and supplying some of the flow rate of the circulated slurry to the point of use 6, that is, the polishing portion of the wafer, one end of which is connected from the supply pipe and the other end of which is connected to the recovery pipe Pressure control for adjusting the pressure feeding pressure of the slurry supplied to the main circuit according to the flow rate and pressure measured by the flow meter 34 and the pressure gauge 30 to check the flow rate and pressure in the slurry supply line consisting of Slurry supply system of the semiconductor CMP process, characterized in that the pressure difference between the supply pipe 12 'and the recovery pipe 8' is kept constant by providing the means 40 in the supply portion 4. . 3. The pressure regulating means (40) according to claim 2, wherein the pressure regulating means (40) is a flow regulating valve (44) for adjusting the filling pressure of nitrogen (N ₂ ) in the supply tank (46) for feeding the slurry to the supply pipe by a hydraulic method. Slurry supply system of the semiconductor CMP process.