JPH06163492A - System for wet automatic washing of wafer - Google Patents

Abstract

PURPOSE:To provide a system which can conduct bath-to-bath transfer of wafers with proper transfer patterns and well prevent bumping phenomenon due to generation of natural oxide films accompanying bath-to-bath transfer after etching washing treatment and due to reaction of a specific chemical solution with deposited water of a wafer. CONSTITUTION:In this system of multibath dipping type which comprises chemical solution baths 3, 5, 7 and pure water baths 4, 6, 8 arrayed in compliance with the wafer washing treatment step, a transfer robot 10 which conducts bath-to-bath transfer of a wafer along the arrangement of these washing baths, and a transfer robot controller 12, and makes washing treatment of a wafer transferred from a preceding treatment step according to a specified washing process flow, the transfer robot is controlled in operation by setting the bath-to- bath transfer speed of wafers at high speed VH in the transfer position from the hydrofluoric acid bath 5 to the pure water bath 6, and the pull-up speed of wafers from the pure water bath at low speed VL in the transfer position from the pure water baths 4, 6 to a sulfuric acid bath 7 which reacts with water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet automatic wafer cleaning system for silicon wafers used in the semiconductor manufacturing field.

[0002]

2. Description of the Related Art A multi-tank immersion type wet station is known as the above-mentioned wet automatic cleaning system for wafers. This multi-bath immersion type wet station is composed of chemical baths and deionized water baths that are alternately arranged in correspondence with the wafer cleaning process, and a transfer robot (horizontal, vertical two-way transfer) that transfers wafers between the cleaning baths. It consists of a combination of a robot with a Cartesian coordinate system) and a control part of the transfer robot.
A wafer carried in from the previous processing step is cleaned while being transferred between tanks according to a designated cleaning process flow, and a typical cleaning method is an RCA cleaning method.

Further, as a control unit of the transfer robot, a control system in which a sequencer, a positioning module, a servo amplifier and the like are combined is generally adopted. Conventionally, a cleaning tact, shake during transfer, vibration, etc. are taken into consideration. The transfer speed of the transfer robot is set to a constant speed (for example, the transfer time between tanks is about 4 to 5 seconds) regardless of the transfer position between the tanks, and the wafer is transferred.

[0004]

By the way, when the wafer is automatically transferred between the tanks by the transfer robot as described above, the following problems arise depending on the cleaning process. That is, (1) in the cleaning process flow, the surface of the silicon wafer that has been subjected to the etching cleaning treatment with a hydrofluoric acid cleaning liquid (a specific composition is a solution containing hydrofluoric acid, hydrogen peroxide, and water) is in an active state. When exposed to the atmosphere (oxygen) during transportation, a natural oxide film is formed on the wafer surface. For this,
At the transfer position where the wafer is transferred from the hydrofluoric acid tank to the next pure water tank, if the inter-tank transfer time is long, the formation of an oxide film is promoted and the active state of the wafer surface is impaired.

(2) Further, when a chemical solution such as sulfuric acid or boiled phosphate is used in a cleaning step such as resist removal after the etching cleaning step or removal of metal impurities adhering to the wafer surface, a deionized water tank is used. The water adhering to the wafer surface reacts violently with the chemical solution in the process of loading the wafer pulled up from the above into the chemical solution tank, and the bumping phenomenon causes the chemical solution mist to be scattered around. In this case, the larger the amount of water brought in from the pure water tank to the chemical tank, the larger the amount of mist generated by the reaction between the chemical solution and water, which disturbs the clean atmosphere in the wet station and significantly affects the surrounding structures. It causes various disorders such as corrosion.

The present invention has been made in view of the above points, and its purpose is to prevent the occurrence of the troubles described in the above-mentioned problems and to perform wet automatic cleaning so that wafers can be transferred between tanks in an appropriate transfer pattern. To provide a system.

[0007]

In order to achieve the above object, the present invention provides a high-speed wafer-to-tank transfer speed at the transfer position from the etching chemical liquid tank to the pure water tank in the cleaning process flow, and At the transfer position to the chemical solution tank that reacts with water, the wafer is pulled up from the pure water tank at a low speed to control the operation of the transfer robot.

[0008]

In the above description, first, by setting the inter-tank transfer speed of the wafer to be higher than the standard transfer speed at the transfer position from the etching chemical liquid tank to the pure water tank, the wafer is exposed to the surrounding atmosphere during the inter-tank transfer. Since the contact time is shortened, the natural oxide film generated on the wafer surface activated by the etching cleaning process is suppressed accordingly.

Further, at the transfer position from the pure water tank to the chemical liquid tank such as sulfuric acid which reacts with water, the pulling speed at the time of pulling up the wafer from the pure water tank (specifically, ascending stroke until the wafer comes out on the water surface). By slowing down the speed to a low speed, the surface tension acts on the water adhering to the wafer surface, carrier, etc. in the process of pulling up from the pure water tank, and the water drainage is greatly improved, and the wafer pulling speed is set to, for example, 5 cm / sec or less. As a result, almost no water droplets remain on the surface of the wafer, and the amount of water brought into the chemical liquid tank at the subsequent stage is close to zero. Therefore, when the wafer is loaded into the chemical solution tank, unreasonable reaction between water and the chemical solution does not occur.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. First, in FIG. 1, 1 is a loader unit of the wet station, 2 is an unloader unit, and the loader unit 1
Between the unloader section 2 and the unloader section 2, an ammonia chemical solution tank 3, a pure water tank 4, a hydrofluoric acid chemical solution tank 5, a pure water tank 6, a sulfuric acid chemical solution tank 7, a pure water tank 8 and a drying tank 9 are lined up in order from the loader side. It has been deployed at. A transfer robot 10 is installed above the cleaning tanks. The transfer robot 10 is equipped with a mechanical hand 10a that holds a wafer 11 or a carrier that contains a wafer, and moves along the direction in which the cleaning tanks are lined up while operating the mechanical hand 10 to move up and down. It is a Cartesian robot that performs inter-tank transfer, and transfers wafers between tanks so that a cleaning process is performed based on a command from the control unit 12.

FIG. 2 is a diagram showing the configuration of the control unit 12, which includes a sequencer 13, a positioning module 14,
The servo amplifier 15 and the sequencer 13 are composed of a cleaning process flow pattern, an input of program data such as a moving speed at each transfer position between tanks, and an operation panel (computer) 16 for giving an operation command and the like. .

With such a configuration, the wafer 11 carried into the wet station from the previous process step is loaded by the loader unit 1.
After the wafer is transferred to the transfer robot 10 in accordance with the specified cleaning process flow, the wafer is transferred between the tanks so that the wafers are alternately immersed in the chemical solution tank and the pure water tank as shown by the arrow in the figure, and the cleaning process is performed. , And is sent to the unloader unit 2 through a drying process. Here, of the arrows displayed in the figure for each of the inter-tank transport positions, the solid line arrow is the standard speed V _S , the dotted line arrow is the high speed V _H , and the chain line arrow is the low speed V _L.
Represents a wafer transfer process, and the transfer robot 10 is operationally controlled in accordance with this transfer pattern.
That is, in the position for conveying inter-bath hydrofluoric acid chemical tank 5 to the next deionized water tank 6, the wafer transport speed standard speed V _S
Is set to a high speed V _H , which is faster than that of the above, and in the inter-tank transfer position from the pure water tank 4 or 6 to the sulfuric acid chemical solution tank 7, the wafer pulling speed from the pure water tanks 4 and 6 is set to a low speed _VL . It is set.

The speed setting data is input from the operation panel 16 to the sequencer 13 in advance and stored therein, and is given to the positioning module 14 in combination with a cleaning process flow designated for each wafer cleaning process. The operation of the robot 10 is controlled based on the data.

[0014]

As described above, according to the automatic cleaning system of the present invention, at the transfer position from the etching chemical solution tank to the pure water tank, the wafer-to-tank transfer speed is high and the chemical solution that reacts with water from the pure water tank is high. At the transfer position to the tank, the wafer pulling speed from the pure water tank is set to a low speed to control the operation of the transfer robot, so that the following effects can be obtained.

(1) It is possible to suppress the generation of a natural oxide film on a wafer which is generated during the inter-bath transfer from the etching cleaning process to the next pure water tank. (2) In the inter-tank transfer process from the pure water tank to the chemical solution tank that reacts with water (for example, sulfuric acid, phosphoric acid, etc.), it is possible to suppress the retention of water droplets on the wafer surface and almost eliminate the introduction of water into the chemical solution tank. This prevents damage caused by the reaction between water and the chemical solution.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wet automatic cleaning system according to an embodiment of the present invention and a wafer-to-tank transfer pattern.

FIG. 2 is a configuration diagram of a control unit of the transfer robot in FIG.

[Explanation of symbols]

 4 Pure Water Tank 5 Hydrofluoric Acid Chemical Solution Tank 6 Pure Water Tank 7 Sulfuric Acid Chemical Solution Tank 10 Transfer Robot 11 Wafer 12 Controller

Claims (1)

[Claims] 1. A chemical treatment tank, a deionized water tank, which are lined up corresponding to a wafer cleaning process, a transfer robot for transferring wafers between the tanks along the arrangement of these cleaning tanks, and a controller for the transfer robot. In a multi-tank immersion wet-type automatic wafer cleaning system that cleans wafers carried in from a process according to a specified cleaning process flow, the wafer inter-tank transfer speed is increased at the transfer position from the etching chemical solution tank to the pure water tank. In the transfer position from the pure water tank to the chemical liquid tank that reacts with water, the wet robot automatic cleaning system is characterized in that the wafer pulling speed from the pure water tank is set to a low speed to control the operation of the transfer robot.