KR100447987B1 - Slurry Feeding Equipment for Chemical Mechanical Polishing Process - Google Patents

Abstract

The present invention discloses a slurry supply apparatus for a chemical mechanical polishing process. In the disclosed invention, a second tank 21 is arranged between the first tank 20 in which the slurry is stored and the polishing equipment. At least one filter (31,32) is disposed between the first and second tanks (20, 21), each filter (31, 32) in order to gradually decrease the pore size to filter from a slurry with a large particle size Are placed as. A pump 80 is arranged between the filter 31 and the first tank 20. The pump 80 and the first tank 20 are connected by a bypass line 41, and a relief valve 50 is installed in the bypass line 41. Before and after the filters 31 and 32, deionized water withdrawal and inlet lines 42 and 43 are connected to allow the blocked filters 31 and 32 to be drilled with deionized water. Meanwhile, discharge lines 46 and 47 are connected to the bottom of each filter 31 and 32 to remove the slurry lumps deposited on the bottom thereof, and air valves 53 and 54 are connected to each discharge line 46 and 47. Is installed. Air vent lines 44 and 45 are connected to the upper ends of each filter 31 and 32, and relief valves 51 and 52 are installed to each air vent line 44 and 45. The pressure gauges 60, 61, 62 are provided before and after each filter 31, 32 so that the clogging state of the filters 31, 32 may be known.

Description

Slurry Feeder for Chemical Mechanical Polishing Process

The present invention relates to a slurry supply apparatus for a chemical mechanical polishing process, and more particularly, to a slurry, which is an abrasive, by chemical mechanical polishing (CMP) equipment to planarize the surface of a wafer. It relates to a device for supplying.

In addition to the advances in semiconductor technology, high speed and high integration of semiconductor devices is progressing, and along with this, the necessity of miniaturization of patterns is increasing, and the size of patterns is also required to be highly accurate. This also applies to device isolation regions that occupy a wide area in semiconductor devices.

LOCOS device isolation films are mostly used for device isolation of current semiconductor devices. This LOCOS device isolation film is obtained by selectively localizing a substrate.

However, in the LOCOS isolation layer, a bird-shaped bird's beak is generated at an edge portion thereof, and thus a leakage current is generated while expanding the area of the isolation layer.

Therefore, conventionally, an STI (Shallow Trench Isolation) device isolation film having a narrow width and excellent device isolation characteristics has been proposed, and the device isolation film is illustrated in FIG. 1.

As shown, an anti-oxidation pattern, for example, a silicon nitride film pattern 3, is formed on the semiconductor substrate 1 so that the device isolation region is exposed. In this case, the device isolation region may be between the device and the device, or may be a region between the wells. At this time, the device isolation region between the wells occupies a larger area than the device isolation region between the device and the device.

Thereafter, the exposed semiconductor substrate 1 is etched by a predetermined depth to form a trench. Subsequently, an oxide film 2 is deposited to sufficiently fill the inside of the trench, and then a chemical mechanical polishing (CMP) process is performed to expose the surface of the nitride film 3 to form an STI type device isolation film 4. Thereafter, the antioxidant pattern is removed in a known manner.

A method mainly used in the STI planarization process is a chemical mechanical polishing method for achieving planarization by removing a predetermined thickness of an interlayer insulating film by polishing a wafer on a polishing plate using a slurry.

The configuration of such a chemical mechanical polishing equipment is briefly described as follows. A polishing plate with a polishing pad is supported by a rotating shaft, and a carrier plate on which a wafer is fixed is disposed on the upper portion of the polishing plate and is also supported by a rotating shaft. On the other hand, the nozzle which supplies a slurry on a wafer is arrange | positioned at the upper side of one side of an abrasive plate.

The wafer is polished by the polishing plate and the carrier plate which are rotated in opposite directions in the state in which the slurry is supplied from the nozzle, as described above, so as to be flattened.

As such, the polishing equipment utilizes a slurry, and therefore must supply the slurry to the polishing equipment, which is shown in FIG.

As shown, the slurry tank 10 is connected to the polishing equipment C, and a filter 14 for removing the slurry having a predetermined size or more is provided inside the polishing equipment C. As shown in FIG. A tank 11 in which nitrogen gas and a slurry are mixed is disposed between the filter 14 and the slurry tank 10, and a pressure between the vacuum tank 12 and the nitrogen gas is mixed between the mixing tank 11 and the filter 14. A pump 13 is arranged to provide.

On the other hand, in order to circulate the slurry mass filtered by the filter 14 back to the mixing tank 11, the filter 14 is connected to the mixing tank 11 through a separate line, which also has a dedicated filter 15 ) Is installed.

However, due to its cohesive force, the slurry does not become a fine powder as shown in FIG. 3 but becomes agglomerate, so that the slurry agglomerate S is not polished and is pushed, causing scratches on the surface of the nitride film 3. Possession is very high.

To prevent this, the filter 14 has also been used as previously described. However, the conventional slurry supply apparatus has a structure in which the filter 14 is located inside the polishing equipment C and continuously circulates the slurry mass filtered through the filter 14, so that the life of the filter 14 is short. Inevitably, the conventional filter 14 has only adopted a pore having a pore of 10 µm or more.

By the way, the slurry is not agglomerated to produce a scratch only because the particle size is 0.35㎛ or less, the conventional filter 14 because the pore is 10㎛ or more, slurry of 0.35 ~ 10㎛ size is the filter 14 It passes through without being filtered, and scratches occur in the nitride film 3 as shown in FIG.

At first glance, replacing the filter 14 used in the conventional apparatus with a pore having a size of about 0.35 μm may solve the above problem, but the conventional filter 14 is located inside the polishing equipment C. As a result, after several hours, the function as a filter is completely lost, thereby causing another problem of filtering even a finely sized slurry that is substantially abrasive. Therefore, it is impossible to apply the microporous filter to the conventional apparatus.

Accordingly, the present invention has been made to solve the problems caused by the conventional supply device, by filtering the slurry mass outside the polishing equipment, the slurry for the chemical mechanical polishing process that can reduce the occurrence of scratches without reducing the life of the filter The purpose is to provide a supply device.

1 is a cross-sectional view showing a device isolation film of the STI method

2 is a view showing a conventional slurry supply device

3 is a view showing that the scratch is generated by the slurry mass

Figure 4 shows a slurry supply apparatus according to the present invention

-Explanation of symbols for the main parts of the drawing-

20; First tank 21; 2nd tank

31; First filter 32; Second filter

40; Main line 41; Bypass line

42; Deionized water inlet line 43; Deionized Water Withdrawal Line

44,45; Air vent lines 46,47; Discharge line

50,51,52; Relief valves 53,54; Air valve

60,61,62; Pressure gauge 80; Pump

In order to achieve the above object, the slurry supply apparatus according to the present invention has the following configuration.

A second tank is disposed between the first tank in which the slurry is stored and the polishing equipment. At least one filter is arranged between the first and second tanks, with each filter being arranged in an order of decreasing pore size so as to filter from a slurry having a larger particle size. A pump is arranged between the filter and the first tank. The pump and the first tank are connected by a bypass line, and a relief valve is installed in the bypass line so that the high pressure due to the clogged filter is supplied to the first tank through the bypass line.

Before and after the filter, deionized water withdrawal and inlet lines are connected to allow the blocked filter to be drilled with deionized water. On the other hand, at the bottom of each filter, a discharge line is connected to remove the slurry lump deposited on the bottom thereof, and an air valve is installed at each discharge line, so that when flushing with deionized water, the slurry lump passes through the discharge line. To be discharged.

In addition, an air vent line is connected to the top of each filter, and a relief valve is installed at each air vent line, so that the increased pressure inside each filter is exhausted through the air vent line.

On the other hand, a pressure gauge is provided before and after each filter so that the filter is blocked, so that the filter is blocked due to the pressure difference between the pressure gauges, or between the first tank and the pump, between the second tank and the polishing. It is also preferable to install a gauge for measuring the hydrogen ion concentration (pH) of the slurry in the equipment.

According to the configuration of the present invention described above, since the filter for filtering the slurry is disposed outside the polishing equipment, scratch generation can be suppressed without shortening the life of the filter.

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

4 is a view showing a slurry supply apparatus according to the present invention.

As shown, the first and second tanks 20, 21 are connected to the main line 40. The first tank 20 is a tank in which the slurry in which the mass is not filtered is stored, and the second tank 21 is a tank in which only the slurry in which the mass is filtered is stored, and is connected to the polishing equipment.

Thus, at least one filter, in this embodiment two filters 31, 32 is arranged in the main line 40. That is, according to the present invention, the filters 31 and 32 are disposed outside rather than inside the polishing equipment. Therefore, the pore size is not limited due to the life limitation of the filter. On the other hand, the filters 31 and 32 are arranged in order of decreasing pore size so as to remove from the slurry of large particles. In this embodiment, the pore size of the first filter 31 is 1 μm, and the pore size of the second filter 32 is 0.4 μm, which filters particles of 0.35 μm or more, which is a critical size for the polishing function of the slurry. .

A pump 80, which provides power to move the slurry of the first tank 20 through the respective filters 31 and 32 to the second tank 21, is provided between the first tank 20 and the first filter 31. Is installed on the main line 40. In addition, in order to prevent the pump 80 from being overloaded due to clogging of the filters 31 and 32 and causing the pump 80 to fail, the pump 80 and the first tank 20 may also be separated by a separate bypass line 41. Connected, the bypass line 41 is provided with a relief valve 50 which is opened only by a predetermined pressure or more. In addition, the air vent lines 44 and 45 are connected to the upper ends of the respective filters 31 and 32 so that the pressure inside the respective filters 31 and 32 does not rise above the prescribed value, and the respective air vent lines 44 and 45 are connected. ), Relief valves 51 and 52 which are opened only by a predetermined pressure or more are provided.

In order to drill the clogged filters 31 and 32, an inlet line 42 for flushing deionized water into the respective filters 31 and 32 is connected between the second filter 32 and the second tank 21, and withdrawal line 43 is connected between the first filter 31 and the pump 80. In order to prevent deionized water from flowing into the pump 80 and the second tank 21, valves 55 and 56 are installed at each main line 40, and slurry is not flowed to the inlet and outlet lines 42 and 43. In order to prevent this, the valves 57 and 58 are also provided in the inlet and outlet lines 42 and 43. In flushing deionized water, discharge lines 46 and 47 are connected to the lower ends of the filters 31 and 32 in order to discharge the lumps of slurry deposited on the respective filters 31 and 32 from the respective filters 31 and 32. Air valves 53 and 54 are installed in the discharge lines 46 and 47, respectively.

In addition, it is preferable to provide pressure gauges 60, 61, 62 before and after each filter 31, 32 so that the clogging state of the filters 31, 32 can be recognized. In addition, the hydrogen ion concentration of the slurry is sensed between each of the first tank 20 and the pump 80, and between the second tank 21 and the polishing equipment so as to determine whether the filters 31 and 32 are replaced. It is also preferable to provide gauges 70 and 71.

Hereinafter, the operation of this embodiment configured as described above will be described in detail.

Each of the valves 55, 56 of the main line 40 is open, and each of the valves 57, 58 of the deionized water inlet and outlet lines 42, 43 is closed and the slurry of the first tank 20 is closed. The particles having a size of 0.35 μm or more are filtered while passing through the first and second filters 31 and 32 by the pump 80. The slurry in which the large particles are filtered is supplied to the polishing equipment via the second tank 21.

During this operation, it is possible to recognize whether the filters 31 and 32 are clogged by the pressure difference measured by each of the pressure gauges 60, 61 and 62.

On the other hand, when each of the filters 31 and 32 is blocked and the pressure provided from the pump 80 to the filters 31 and 32 becomes higher than the prescribed value, the relief valve 50 of the bypass line 41 is opened, and the predetermined pressure or more is increased. Pressure enters the first tank 20 through the bypass line 41. Therefore, a situation in which an excessive load is applied to the pump 80 and malfunctions is prevented in advance. When the filters 31 and 32 are clogged and the pressure therein becomes above the prescribed value, the relief valves 51 and 52 of the air vent lines 44 and 45 are opened, so that a predetermined or more pressure is applied to each air vent line 44. Through 45).

In order to drill through the filters 31 and 32 which are recognized as clogged by the pressure gauges 60, 61 and 62, the respective valves 55 and 56 of the main line 40 are closed and the deionized water inlet and outlet lines 42, Each valve 57, 58 of 43 is opened in reverse, and then deionized water is flushed into each filter 31, 32 via an inlet line 42. The flushed deionized water is passed through the filters 31 and 32 and then discharged through the withdrawal line 43. On the other hand, the slurry lumps blocking the filters 31 and 32 are discharged from the filters 31 and 32 through the discharge lines 46 and 47 opened by the air valves 53 and 54.

As described above, according to the present invention, the slurry filtration operation is performed outside the polishing equipment, so that slurry lump filtration can be performed without shortening the life of the filter, and scratch generation can be suppressed.

On the other hand, the present invention is not limited to the above-described specific preferred embodiments, and various changes can be made by those skilled in the art without departing from the gist of the invention claimed in the claims. will be.

Claims (2)

A first tank in which the slurry is stored; A second tank disposed between the first tank and the polishing equipment; At least one filter disposed between the first and second tanks to filter a slurry of a predetermined size or more, the filter being disposed in an order of decreasing pore size so as to remove from a larger size slurry; And a motor disposed between the filter and the first tank, the motor for forcing the slurry of the first tank through each filter to the second tank. A dehydration ion inlet line connected between the filter and the second tank for piercing each filter blocked by slurry by flushing with deionized water; A deionized water extraction line connected between the pump and the filter, An air valve installed in the discharge line and configured to discharge slurry agglomerates dropped to the bottom of each filter by the flushed deionized water, A first valve installed between the pump and the filter and between the filter and the second tank, for controlling the deionized water so as not to flow into the pump and the second tank; A second valve installed at each of the inlet line and the outlet line to control the slurry so that the slurry does not flow into the inlet and outlet line; And a pressure gauge arranged before and after each filter to recognize a clogging state of the filter as a pressure difference between the filters. According to claim 1, The pump and the first tank is also connected to the bypass line, the bypass line is provided with a relief valve which is opened only by a predetermined pressure or more, An air vent line is connected to an upper end of each filter, and a relief valve is installed in each air vent line to be opened only by a predetermined pressure or more.