JPH04293579A - Method for washing solid fine particles - Google Patents

Abstract

PURPOSE:To safely and simply wash and dry a surface to be washed without leaving a water mark on the surface to be washed of a washing object by solidifying org. matter to form org. solidified particles and allowing the org. solidified fine particle group to collide with the surface to be washed to wash said surface. CONSTITUTION:When high purity nitrogen gas is supplied to the nozzle 37 of a washing part 30 through a supply pipe 38 at the time of the washing of a semiconductor substrate, the fine particle group formed in a fine particle forming part 10 and stored in a stock part 12 is sent to the nozzle 37 from a feed pipe 13. Whereupon, the fine particle jet stream F dispersed in the high purity nitrogen gas is formed to be sprayed. This fine particle jet stream F is allowed to collide with a surface S to be washed and sent to a drying part 50 to be heated and dried by a heater 53. By this method, the solidified fine particles on the surface to be washed are evaporated and dried.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a surface of an object to be cleaned (for example, a semiconductor substrate) by colliding a group of solid particles with the surface of the object to be cleaned.

0002

[Prior Art] Conventionally, a method is known in which water (pure water) is cooled and solidified into fine particles to form a solid fine particle group, and the solid fine particle group is made to collide with the surface of a semiconductor substrate to clean the surface. . (For example, Nikkei Microdevice 1989
July issue p. 72, ULTRA CLEAN TEC
HNOLOGY vol. 1 No. 1 p. 35-4
2)

In such conventional methods, isopropyl alcohol (hereinafter referred to as IPA) is applied using an apparatus as shown in FIG. Steam heating drying method ("Optimal precision cleaning technology" editor: Yutaka Hiratsuka et al., Techno System Co., Ltd. (1990) p.
．． 191~).

[0004] In this device, the IP introduced into the tank 81
A is heated with a heater 82 to generate IPA vapor, and this I
PA vapor is heated by a heater 83 provided on the side wall. The wafer 84 to be cleaned is exposed to heated steam to melt solidified fine particles on the surface to be cleaned. This wafer 84 is cooled by a cooling pipe 85, and the vapor on the surface to be cleaned is condensed and liquefied. The liquefied IPA is discharged from the condensate receiver 86 to the outside. Figure 2
Inside, 87 is an IPA canister, and the IPA solution inside is guided to the tank 81 through a filter 88 under pressure from high-purity nitrogen gas. 89 is a fan that ventilates the drying chamber, and 90 is a filter provided between the inside of the drying chamber and the outside.

[0005]

However, the apparatus shown in FIG. 2 is complicated and large-scale. Furthermore, in this method, a large amount of liquid IPA is used at high temperature, and at the same time, a large amount of highly flammable high-temperature IPA vapor is handled.
In order to create such equipment, it is necessary to install various equipment in terms of both software and hardware, resulting in equipment that is expensive and difficult to maintain.

[0006] An object of the present invention is to provide a particulate cleaning method that can safely dry a surface to be cleaned without leaving water marks on the surface to be cleaned and without using a complicated drying device. It's about doing.

[0007]

[Means for Solving the Problems] The cleaning method according to the present invention solidifies an organic substance solution to generate solidified organic substance particles, and causes the generated solidified organic substance particles to collide with a surface to be cleaned to be cleaned. It is used for cleaning.

[0008]

[Operation] Solidified fine particles formed by solidifying an organic solution collide with the surface to be cleaned, thereby cleaning the surface to be cleaned. Therefore, in the drying step that follows the cleaning step, the solidified fine particles on the surface to be cleaned can be evaporated and dried by simply heating the object to be cleaned.

[0009]

[Embodiment] An embodiment of the present invention will be explained with reference to FIG. This cleaning apparatus is comprised of a particulate generation section 10, a cleaning section 30, a drying section 50, and a control section and a semiconductor substrate transport system (not shown).

[0010] The particulate generation unit 10 generates organic matter, for example,
It generates fine particles of isopropyl alcohol (hereinafter referred to as IPA) with a melting point of -88.5 to -89.5°C and a boiling point of 82.3°C. A particulate stock section 12 for storing;
It has a particulate feed pipe 13 that supplies particulates from the stock part 12 to the next stage cleaning part 30. Fine particle generator 1
In method 1, fine particles are generated by finely spraying high-purity IPA into a clean atmosphere maintained at liquid nitrogen temperature, for example.

The cleaning section 30 has a cleaning tower 31, and a holding section 311 for holding a semiconductor substrate SUB to be cleaned is provided on the top of the cleaning tower 31. A drain pipe 32 is connected to the lower part of the cleaning tower 31, and this drain pipe 32 has a
A drain tank 33 for storing molten liquid 39 is connected. A heater section 34 for melting particulates is provided at the connection between the drain pipe 32 and the drain tank 33. Cleaning tower 3
1 is provided with a discharge pipe 35 for suctioning and discharging dirty particles, etc., and a drain tank 33.
A discharge pipe 36 is provided at the top of the tube 36 for sucking the molten particles and discharging them to the outside. Furthermore, inside the cleaning tower 31, a particulate feed pipe 13 of the particulate generating section 10 extends from below to above, and a nozzle 37 is provided at the tip thereof. A low-temperature, high-purity nitrogen gas at a temperature that does not melt the particulate group is supplied to this nozzle 37 from a nitrogen gas supply pipe 38, and the particulate group is conveyed by this nitrogen gas. In other words, the low-temperature high-purity nitrogen gas is used as a carrier gas for the particles.

The drying section 50 has a drying tower 51. A holding section 52 for holding the semiconductor substrate SUB is provided in the drying tower 51, and a holding section 52 for holding the semiconductor substrate SUB is provided below the holding section 52.
A heater 53 is provided to heat the. A high-purity inert gas, such as nitrogen gas, is supplied to the holding part 52 through a gas supply pipe 54 in order to wash away the front and back surfaces of the semiconductor substrate. In addition, vaporized IPA is placed on the top of the drying tower 51.
A discharge pipe 55 is provided to discharge the water to the outside.

Furthermore, although not shown, a transport device for the semiconductor substrate SUB is provided between the cleaning section 30 and the drying section 50. This transport device transports a semiconductor substrate in a low-humidity, high-purity inert gas (for example, nitrogen gas) atmosphere that is maintained at a temperature that does not melt fine particles attached to the surface of the semiconductor substrate.

In the cleaning apparatus having such a configuration, a semiconductor substrate is cleaned in the following manner. Nozzle 3 of cleaning section 30
When high purity nitrogen gas is supplied to 7 through the supply pipe 38,
The fine particles generated in the fine particle generation section 10 and stored in the stock section 12 are sent to the nozzle 37 through the feed pipe 13, and are atomized fine particle stream F dispersed in high purity nitrogen gas.
It is sprayed from the nozzle 37. This atomized particle flow F
collides with the surface S to be cleaned of the semiconductor substrate SUB, thereby precisely cleaning the surface S of the semiconductor substrate to be cleaned. Fine particles that collide with the surface to be cleaned and are redispersed inside the cleaning tower 31 are
Gravity or a discharge pipe 36 provided at the top of the drain tank 33
The liquid falls downward due to the suction force, is heated by the heater 34 installed at the connection between the drain pipe 32 and the drain tank 33, is melted, and is stored as a liquid in the drain tank 33. The heating by the heater 34 only requires the minimum amount of heating necessary to melt the fine particles, and it is only necessary to remove the latent heat of melting, and the melted liquid has an extremely low temperature.

[0015] If necessary, the inside of the cleaning tower 31 is suctioned through a discharge pipe 35 installed at the top of the cleaning tower 31, and the dirty particles redispersed inside the cleaning tower 31 are discharged to the outside. They may be prevented from adhering to the surface to be cleaned of the semiconductor substrate.

The semiconductor substrate precision-cleaned in this way is transported to the drying section 50 through the above-mentioned transport device. At this time, the inside of the transport device is kept in a low-humidity, high-purity inert gas (for example, nitrogen gas) atmosphere that is maintained at a temperature that does not melt the fine particles attached to the surface to be cleaned. The fine particles adhering to the surface are transported to the drying section 50 without being melted, and are heated and dried by the heater 53 of the drying section 50. By doing so, it is possible to dry the surface of the semiconductor substrate to be cleaned without leaving any watermarks. The amount of IPA particles vaporized in the drying tower 51 is extremely small, and high-purity nitrogen gas is introduced into the drying tower 51 to wash the front and back surfaces of the semiconductor substrates, so the inside of the drying tower 51 is at the explosion limit. (The explosive range is 2.0 to 12.0 vol% when mixed with air at room temperature and pressure) The IPA concentration is diluted to below, and this diluted gas is sucked through the exhaust pipe 55 and discharged to the outside. be done.

Note that organic substances other than IPA, such as alcohols such as methyl alcohol and ethyl alcohol, and aromatic organic substances such as benzene, may be used. However, when using these organic substances, it is natural to use one that does not cause unevenness such as water marks after drying. Furthermore, ice particles may be used in combination with the solidified organic substance particles. Furthermore, the object to be cleaned is not limited to semiconductor substrates. Furthermore, the present invention is not limited in detail to the above-described embodiments, such as that the semiconductor substrate held by the cleaning tower 31 may be in a vertical position.

[0018]

As explained in detail above, according to the present invention, since the cleaning is performed by colliding the organic matter solidified fine particles formed by solidifying the organic matter with the surface to be cleaned, the drying process subsequent to the cleaning process is improved. In this method, the solidified particles on the surface to be cleaned can be evaporated and dried by simply heating the object to be cleaned, and a steam heating drying device required for a conventional cleaning device using ice particles is not required.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram schematically showing an apparatus for cleaning semiconductor substrates using a cleaning method according to the present invention.

[Fig. 2] A schematic overall configuration diagram showing an example of a conventional steam heating drying device

[Explanation of symbols]

10 Fine particle generation section 11. Fine particle generator 30 Cleaning section 31 Washing tower 33 Drain tank 37 Nozzle 38 Nitrogen gas supply pipe 50 Drying section 51 Drying tower 53 Heater

Claims (1)

[Claims] 1. Solid fine particle cleaning characterized by solidifying an organic substance solution to produce organic solidified fine particles, and causing the generated organic solidified fine particles to collide with a surface to be cleaned to clean the surface to be cleaned. Method.