KR100649307B1 - Method for Preventing Charging in Scrubbing Process - Google Patents

Abstract

The present invention relates to a method of cleaning a semiconductor wafer, and more particularly, to a method of cleaning a semiconductor device by minimizing damage due to electrostatic charge by scrubbing with a gas during the cleaning of the silicon wafer in the semiconductor manufacturing process.

Another object of the present invention is a wafer 100; An injection tube 110 for ejecting pure water and gas into the wafer 100; A control unit 120 connected to the injection pipe 110 to control an amount of pure water or gas and selection of pure water or gas; A gas supply unit 130 supplying gas to the control unit 120; And a pure water supply unit 140 for supplying pure water to the controller 120.

Therefore, the method for preventing the electrostatic charge during the scrubbing process of the present invention has the effect of reducing the defective rate by the electrostatic charge and improve the yield by preventing the electrostatic charge using a neutral gas during the rotation of the wafer.

Scrubbing, wafer, electrostatic charge.

Description

Method and apparatus for preventing electrostatic charge during scrubbing process {Method for Preventing Charging in Scrubbing Process}             

1 is a side view for explaining a conventional cleaning equipment.

2 is a plan view for explaining a conventional cleaning equipment.

3 shows damage to a wafer due to electrostatic charge.

4 is a view showing an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

11: base plate 12: spin cup (spin cup)

13: 1st pure water spray nozzle 14: 2nd pure water spray nozzle

15 nozzle clamp 16 wafer

17: spin chuck 18: ultrasonic generator

19: ultrasonic cleaning arm 20: brush

21: Brush Arm 31: Die Dressing

32: bad die 100: wafer

110: injection pipe 120: control unit

130: gas supply unit 140: pure water supply unit

The present invention relates to a method of cleaning a semiconductor wafer, and more particularly, to a method of cleaning a semiconductor device by minimizing damage due to electrostatic charge by scrubbing with a gas during the cleaning of the silicon wafer in the semiconductor manufacturing process.

Semiconductor devices are constructed in a manufacturing environment known as a clean room, which is specifically designed for the filtration and removal of fine contaminants. Particle control is very important for semiconductor fabrication results and directly affects device yield, since particles that stick to the device surface can ruin the entire microelectronic circuit. Despite the clean manufacturing environment, a cleaning step is generally performed throughout the semiconductor manufacturing operation to remove particles from the wafer on which the circuit is manufactured.

The cleaning step is particularly important before significant processes such as lithography and after highly contaminated processes such as chemical mechanical polishing. For example, CMP machines, which are generally used to planarize or smooth the surface of a semiconductor wafer, are generally used for polishing slurry (such as silica or alumina) that generally comprise abrasive particle materials of generally sub-micron size. slurry). Along with the particles removed from the wafer itself during polishing, hundreds to thousands of these particles can generally be found on the polished wafer surface.

Cleaning methods common to semiconductor processes include cleaning with acid rinse and deionized water or with a surfactant solution. Cleaning methods also include mechanical buffing and combinations thereof, such as ultrasonic and megasonic cleaning, brush cleaning, or rinses and solutions. For example, US Pat. No. 5,562,778 to Koretsky et al. Describes ultrasonic wafer cleaning using ultrasonic waves incident on a cleaning liquid flow, such as deionized water, while the wafer rotates about an axis.

1 and 2 are a side view and a plan view for explaining a conventional cleaning equipment.

The spin cup 12 is positioned in the form of a cylinder with an opening formed thereon on the support plate 11, and is configured to surround the wafer in the raised position. One side ends of the first and second pure spray nozzles 13 and 14 are positioned on the spin cup 12, and the spray nozzles are formed by using a fixing device such as a nozzle clamp 15. It is fixed to the side, and configured to spray pure water toward the wafer at one end. At this time, the second pure water jet nozzle 14 is a predetermined angle clockwise along the circumference of the spin cup 12 with respect to the center of the spin chuck 17 from the first jet nozzle 13. For example, it may be mounted at a position rotated by an angle of about 90 °. At this time, the spin chuck 17 is positioned inside the spin cup 12, and its rotation is performed so that the pure water sprayed from the first and second pure spray nozzles 13 and 14 is evenly distributed on the wafer. It is configured to be possible. The wafer is seated on the spin chuck 17. An ultrasonic cleaning arm 19 is positioned outside one side of the spin cup 12, and the ultrasonic cleaning arm 19 is configured to allow the end portion to rotate on the wafer about a fixed axis by a predetermined angle during ultrasonic cleaning. . An ultrasonic generator 18 for generating ultrasonic waves is mounted below the end of the ultrasonic cleaning arm 19. The brush arm 21 is mounted at a position symmetrical with the ultrasonic cleaning arm 19 with respect to the center of the spin chuck 17. During brush cleaning, an end portion of the spin chuck 17 may rotate by a predetermined angle on the wafer about a fixed axis. It is configured to be. A brush 20 is mounted below the end of the brush arm 21.

In the cleaning equipment configured as described above, cleaning of the wafer proceeds as follows.

The wafer 16 is seated on the spin chuck 17, and the spin chuck 17 and the wafer 16 start to rotate after the spin cup 12 moves upward to surround the wafer. At this time, the spin cup 12 is used to prevent the broken wafer pieces from colliding with the equipment wall and damaging the equipment when the wafer is broken during the process. The cleaning starts when the set rotation speed is reached, and the ultrasonic cleaning and the brush cleaning are repeatedly performed. When the process proceeds, pure water is first sprayed onto the wafer 16 from the first and second pure water spray nozzles 13 and 14. At this time, the positions of the first and second pure water spray nozzles 13 and 14 are determined so that the injected pure water flows in a vortex form in order to enhance the cleaning effect. Thereafter, one end of the ultrasonic cleaning arm 19 or the brush arm 21 configured as described above is advanced on the wafer 16. In this case, in the case of ultrasonic cleaning, ultrasonic waves are generated from the ultrasonic generator 18 attached to the arm to clean the wafer surface. In the case of brush cleaning, the brush 20 attached to the arm contacts the surface of the wafer 16. Cleaning is in progress.

However, spin scrubbing and rinsing provide an environment in which electrostatic charges are created and formed. In the spinning chamber, highly insulative pure shears across the wafer surface, producing a high level of electrostatic charge. Although electrostatic charge is generated inside most semiconductor process tools, the highest levels of electrostatic charge occur within spin scrubbing or cleaning environments. Such high levels of surface voltages, for example voltages of about 60 volts, can damage circuits and / or devices (eg transistors) fabricated on the wafer.

3 is a wafer damaged by an electrostatic charge.

3, 31 is a good die, and 32 is a bad die damaged by an electrostatic charge.

The charged wafer also attracts and bonds airborne particles and contaminants to the wafer surface upon exiting the spinning chamber. In addition, a charged wafer exiting the spinning chamber may cause electrostatic discharge (ESD) if it is too close to a grounded object. This discharge can cause electromagnetic interference (EMI) that can affect the surrounding manufacturing environment. In extreme cases, ESD can cause the fabrication tool to lock and the wafer often have to be reprocessed.

Known approaches to reducing the formation of static electricity include lowering the spin rate and / or reducing the flow rate of deionized water. This approach may reduce the degree of static buildup (eg 10-20%), but may be insufficient to avoid damaging the circuit or device. Therefore, this approach increases cleaning time and lowers yield.

There is a need to reduce the build up of static electricity during cleaning or cleaning of semiconductor wafers to protect circuits and devices fabricated thereon.

Therefore, the present invention is to solve the problems of the prior art as described above, using the pure water (DI water) and gas in the scrubbing process to remove the particles, but to minimize the incidental adverse effects to reduce the defective rate due to electrostatic charge and yield SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for preventing electrostatic charge in a method of cleaning a semiconductor device for improving the efficiency.

The object of the present invention is a first step of rotating the wafer 100; A second step of injecting a gas into the wafer through an injection tube (110) to reduce electrostatic charge on the rotating wafer (100); A third step of removing particles by spraying pure water on the wafer through the injection pipe (110); And a fourth step of injecting a gas into the wafer 100 to reduce the electrostatic charge generated in the third step.

Another object of the present invention is connected to the injection tube 110, the injection tube 110, and the injection tube 110 to selectively discharge pure water and gas in a single opening on the wafer 100, the wafer 100, to remove the electrostatic charge The control unit 120 and the control unit 120 to supply gas to the gas, to spray pure water for cleaning, to supply gas to remove the electrostatic charge, and to control the order and amount of the gas and the pure water. It is achieved by a device for preventing an electrostatic charge, characterized in that it comprises a gas supply unit 130 for supplying gas to the control unit 120 and a pure water supply unit for supplying pure water to the control unit 120.

Details of the above object and technical configuration of the present invention and the effects thereof according to the present invention will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

The present invention minimizes defects caused by static electricity by scrubbing using gases such as pure water and gas when scrubbing for particle removal, and other gases may be used according to the purpose of use, and electrostatic charges by high speed rotation may be reduced by reducing the rotational speed of the wafer. It reduces the damage caused by static electricity because the pure gas is used that the instantaneous potential difference is generated by pure injection after high speed rotation. Depending on the properties of the particles in the various layers, the chemical properties of the gases used will also vary.

4 is a view showing an embodiment of the present invention.

Wafer 100, the injection pipe 110 for ejecting pure water and gas, the control unit 120 for selecting and transmitting the amount of pure water and gas and the pure water or gas, gas supply unit 130, pure water supply unit 140 have.

The wafer 100 is a wafer before performing a predetermined process and is prepared in a cleaning apparatus to prevent foreign matter and electrostatic charge on the wafer 100.

The injection pipe 110 is a pipe for ejecting pure water and gas.

The controller 120 selectively serves to supply gas or pure water to the injection pipe 110 and compresses and sends gas or pure water.

The gas supply part 130 serves to supply gas, and varies the chemical properties of the gas used according to the characteristics of the particles of various layers formed in the preceding process.

The gas generally uses N ₂ gas, and may be used by mixing a gas suitable for each characteristic according to the type of particles generated in the preceding process.

The gas also contains anions and cations.

The pure water supply unit 140 serves to supply pure water.

The method for driving the apparatus first rotates the wafer 100 where a predetermined process is completed, and injects neutral gas to which the cation or anion is added to the center of the wafer 100.

When the surface of the wafer is scrubbed with a positive or negative charge as a by-product of the process, the wafer is uniformly distributed on the wafer, resulting in the centering of the wafer due to the centrifugal force due to the high speed rotation of the wafer. Since only the central portion is damaged by static electricity, to prevent this, if injected to the rotating wafer with neutral gas added with cations or anions, the electrostatic charge collected in the center of the wafer can be reduced or prevented.

The process is performed for a predetermined time, and pure water is ejected to the wafer to clean the wafer.

Afterwards, neutral gas to which cations or anions are added is injected to the center of the wafer.

When cleaning a wafer with pure water, electrostatic charges are generated by the wafer, pure water, and the surrounding environment, which are centered by the rotation of the wafer. Neutral gas containing cations or anions is injected into the center of the wafer to prevent the wafer from being damaged by the electrostatic charge.

The above process removes particles present on the wafer surface and prevents damage due to electrostatic charges.

The cationic ion gun / electron gun of the gas ejection method in the known art is possible in a special amber, such as the electron gun of a scanning electron microscope (SEM) device, and there are quite a few additional devices to implement this in the scrubbers currently in use. It should be equipped with the environment, but the configuration of the present invention does not need any additional device supplement and modification because only the neutral gas to which the cation or anion is added to the pure injection device of the known scrubber.

It will be apparent that changes and modifications incorporating features of the invention will be readily apparent to those of ordinary skill in the art by the invention described in detail. It is intended that the scope of such modifications of the invention be within the scope of those of ordinary skill in the art including the features of the invention, and such modifications are considered to be within the scope of the claims of the invention.

Therefore, the method for preventing the electrostatic charge during the scrubbing process of the present invention has the effect of reducing the defective rate by the electrostatic charge and improve the yield by preventing the electrostatic charge using a neutral gas during the rotation of the wafer.

Claims (6)

A method for preventing electrostatic charge during a scrubbing process of a semiconductor wafer, A first step of rotating the wafer 100; A second step of injecting a gas into the wafer (100) through the injection pipe (110) to reduce the electrostatic charge on the rotating wafer (100); A third step of removing particles by spraying pure water on the wafer 100 through the injection pipe 110; And A fourth step of injecting a gas into the wafer 100 to reduce the electrostatic charge generated in the third step Method for preventing the electrostatic charge, comprising a. In the scrubbing apparatus of a semiconductor wafer, Wafer 100; An injection tube (110) for selectively ejecting pure water and gas into the wafer (100) in a single opening; Connected to the injection pipe 110, supply gas to remove the electrostatic charge, inject pure water for cleaning, resupply the gas to remove the electrostatic charge, supply order of the gas and pure water And controller 120 for adjusting the amount; A gas supply unit 130 supplying gas to the control unit 120; And Pure water supply unit 140 for supplying pure water to the control unit 120 Apparatus for preventing electrostatic charge, comprising a. The method of claim 2, The supply gas of the gas supply unit 130 is a device for preventing electrostatic charge, characterized in that the chemical properties of the gas used according to the characteristics of the particles of the various layers formed in the previous process. The method of claim 3, wherein And said feed gas is N ₂ . The method of claim 3, wherein And said feed gas contains an anion and a cation. The method of claim 2, The control unit (120) is a device for preventing the electrostatic charge, characterized in that for supplying compressed gas or pure water to the injection pipe (110).

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