JP4243154B2 - Slurry supply method - Google Patents

Description

  The present invention relates to a slurry supply apparatus and a slurry supply method for supplying a slurry for polishing a semiconductor substrate.

In the conventional slurry supply device, the remaining amount of the slurry in the tank in the slurry supply device is managed by detecting the liquid level of the liquid level sensor, and replenishment of slurry and stop of replenishment are performed based on the detection result (for example, patent document) 1). In the case of a slurry replenishment sequence based on the liquid level detection result by the liquid level sensor, the supply to the chemical mechanical polishing apparatus is stopped for a certain time (for example, 15 minutes) before the liquid level reaches the liquid level sensor for slurry replenishment. When the slurry is replenished, the slurry is dried and agglomerated on the inner wall of the tank between the liquid level stop position when the slurry is replenished and the current liquid level stop position.
JP 2000-61820 A

  In the conventional slurry supply apparatus, the casing of the slurry supply apparatus is exhausted to prevent the slurry atmosphere from diffusing into the clean room. Since the volume of the exhausted air takes in dry air (about 40%) in the clean room, the atmosphere in the casing of the slurry supply device is always dry.

  When the liquid level of the slurry is lowered, the outside air of the tank (atmosphere inside the case of the slurry supply device) is taken into the tank, and in the case of the slurry replenishment sequence by the liquid level sensor, the liquid level up to the liquid level sensor for slurry replenishment When the supply to the chemical mechanical polishing apparatus is stopped for a certain period of time (for example, 15 minutes) before the time reaches, the tank inner wall between the liquid level at which slurry replenishment is stopped and the current liquid level is stopped. It was found that drying and aggregation occurred.

  When the slurry is replenished after being stopped for a certain time or longer, the dried and agglomerated slurry is mixed with the replenished slurry on the inner wall of the tank, so that scratches are generated on the surface of the polished wafer in chemical mechanical polishing.

  Accordingly, an object of the present invention is to provide a supply apparatus and method in which slurry does not dry, aggregate, precipitate, or change in solid content concentration in a tank.

Slurry supply method of the present invention in order to achieve the above object, stores the slurry for performing chemical mechanical polishing, the slurry from the slurry supply apparatus having a tank with a sealing level enough to be outside air distribution a slurry supply method for supplying the liquid surface of the slurry in the tank is, after descending from the position to stop the replenishment of the slurry, fixed up before the slurry on the inner wall of the tank is dried and agglomerated A step of managing the replenishment of the slurry using a timing device is provided so that the slurry is replenished into the tank when time elapses .

In addition, the slurry supply method of the present invention further injects a mist-like liquid into the tank from the spray nozzle , or increases the humidity in the tank using a humidifier connected to the tank, A step of preventing the slurry from drying.

By managing the slurry in the tank as described above , or by injecting a mist-like liquid into the tank or increasing the humidity in the tank using a humidifier connected to the tank, the slurry is It is possible to prevent drying, agglomeration, precipitation, and change in solid component concentration, and to ensure a uniform particle diameter and uniform solid component concentration, thereby enabling uniform polishing.

FIG. 1 is a schematic configuration diagram showing an embodiment of a slurry supply apparatus of the present invention. In FIG. 1, 1 is a sealed slurry tank for storing slurry, 2 is a liquid level sensor for detecting the liquid level of the slurry in the slurry tank 1 and managing the remaining amount of the slurry, 3 is in the slurry tank 1 The spray nozzle 4 for wetting is also a load cell for managing the remaining amount of slurry. Here, the liquid level sensor 2 includes a slurry replenishment sensor 2b and a slurry replenishment stop sensor 2a . The remaining amount of slurry may be managed by at least one of the liquid level sensor 2 or the load cell 4, and only at least one of the components may be provided. 5 is an exhaust pipe for exhausting from the casing 20 of the slurry supply apparatus, 6 is a pipe for supplying the slurry to the slurry tank 1 from the primary side, 7 is a pipe for supplying the slurry from the slurry tank 1 to the chemical mechanical polishing apparatus, Reference numeral 8 denotes a pipe connected to the slurry tank 1 for supplying pure water or a chemical liquid when the inside of the slurry tank 1 is washed. Reference numeral 9 denotes a pipe for discharging slurry or other waste liquid in the slurry tank 1. Further, 10 is a slurry tank 1, a slurry circulation pipe for circulating the slurry, 12 is a humidifier that sends moisture when the liquid level changes in the slurry tank 1, and 11 is moisture between the slurry tank 1 and the humidifier 12. It is a flow path. A pipe 13 is connected to the spray nozzle 3 and supplies pure water or a chemical solution for wetting the slurry tank 1. As a configuration for wetting the slurry tank 1, only the spray nozzle 3 or the humidifier 12 need be provided.

  FIG. 2 is a schematic configuration diagram showing another embodiment of the slurry supply apparatus of the present invention. In FIG. 2, the slurry supply apparatus shown in FIG. 1 is different from the slurry supply apparatus shown in FIG. 1 in that the moisture flow path 11 between the slurry tank 1 and the humidifier 12 is further filled with moisture and dry air when the liquid level changes. This is the point that a pipe 14 that does not change is provided.

  Next, a slurry supply method using the slurry supply device, particularly a slurry replenishment method will be described below.

  The slurry for polishing the silicon substrate is composed of silica powder and a strong alkali dispersant such as ammonia. The primary particles of silica are about 20 to 30 nm, and these are collected to form a secondary of about 0.2 μm. Consists of particles.

The slurry supply device includes a liquid level sensor 2 or a load cell 4 in order to manage the remaining amount of slurry in the slurry tank 1. When the position of the slurry in the slurry tank 1 drops below the slurry replenishment sensor 2 b is a liquid level sensor for starting slurry replenishment, or is recognized as a slurry replenishment position, or, the weight of the slurry tank 1 by the load cell 4, When the slurry replenishment weight is reached, the slurry is supplied from the primary side through the pipe 6, and the position of the slurry reaches the slurry replenishment stop sensor 2 a which is a replenishment stop liquid level sensor, or the weight of the slurry tank 1 is increased by the load cell 4. When the slurry replenishment stop weight is reached, slurry supply from the primary side pipe 6 is stopped. As described above, the slurry replenishment sensor 2 b and the slurry replenishment stop sensor 2 a , or the remaining amount of slurry is managed by the load cell 4. Yes.

However, in the case of this slurry supply method, if the time until the slurry is automatically replenished becomes longer, specifically, if the polishing apparatus stops for a certain time (for example, 15 minutes) during the slurry supply, the slurry replenishment There is a problem that the slurry dries and aggregates on the inner wall of the tank between the stop sensor 2a and the current stop liquid level. As an improvement measure, the slurry supply method of the present invention is such that the slurry liquid level descends from the slurry replenishment stop sensor 2a and the slurry passes through the pipe 6 from the primary side when a certain time (time until the slurry dries and aggregates) elapses. The slurry is replenished and filled before the slurry on the inner wall of the slurry tank 1 is dried and agglomerated to prevent drying. For example, a timer device such as a timer may be used for the management of supplying the slurry so that the liquid level descends from the slurry replenishment stop sensor 2a and the liquid level is restored after a predetermined time. In terms of time, for example, it is set to 10 minutes.

  Next, a method for maintaining wetness and humidity in the slurry tank 1 of the slurry supply apparatus will be described below.

  In addition to preventing slurry drying in the above-described slurry replenishing method, as a further drying prevention measure, as a method of moistening the inside of the slurry tank 1 and maintaining the humidity, spraying a mist liquid from the spray nozzle 3 into the slurry tank 1 Alternatively, the slurry tank 1 is humidified from the humidifier 12 through the moisture channel 11.

  Further, the pipe 14 is used as a control means for preventing the exchange of the dry atmosphere introduced with the lowering of the liquid level of the slurry in the tank and the wet atmosphere, controlling the wetness in the tank, and maintaining the humidity. I have. By flowing the air that moves (in and out) due to the fluctuation of the liquid level of the slurry to the humidifier 12, it is possible to prevent the replacement with the dry outside air and to maintain the humidity of the slurry tank 1. Alternatively, a pipe 14 having a volume of gas that moves (in and out) as the liquid level of the slurry changes is connected to the slurry tank 1 in the housing 20 so that the moisture in the slurry tank 1 and the dried outside air are switched. The humidity in the slurry tank 1 can be maintained.

The schematic block diagram which shows one Embodiment of the slurry supply apparatus of this invention The schematic block diagram which shows other one Embodiment of the slurry supply apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slurry tank 2 Liquid level sensor 3 Spray nozzle 4 Load cell 5 Exhaust piping 6, 7, 8, 9, 13 Piping 10 Slurry circulation piping 11 Humidity channel 12 Humidifier 14 Piping

Claims (3)

It stores the slurry for performing chemical mechanical polishing, a slurry supply method for supplying a slurry from a slurry supply device having a tank with a sealing level enough to be outside air distribution, the slurry in the tank the liquid level of, after descending from the position to stop the replenishment of the slurry, when the predetermined time until before the slurry on the inner wall of the tank is dried and agglomerated has elapsed, to replenish the slurry into the tank Thus, the slurry supply method characterized by including the process of managing the replenishment of the said slurry using a timing device . The slurry supply method according to claim 1, further comprising a step of increasing the humidity in the tank by spraying a mist-like liquid into the tank from a spray nozzle. The slurry supply method according to claim 1, further comprising a step of increasing the humidity in the tank using a humidifier connected to the tank.

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