JPH0878370A - Apparatus and method for cleaning semiconductor substrate - Google Patents

Abstract

PURPOSE: To reduce the amount of a cleaning liq. carried with a cleaned Si wafer held with a chuck mechanism when it is taken up from a cleaning bath by contacting the lower end of the wafer with a liq. removing pole and carrying it. CONSTITUTION: A substrate receiving table 5 has grooves at a pitch wide enough to hold about 50 Si wafers 2 and poles 6 protrudent from a cleaning liq. 7 circulating through a cleaning bath by a circulator. A chuck mechanism carries the wafer 2 on this bath, lowers it into the liq. 7, settles it on the table 5, lifts it and secures it there while the wafer is etched. This mechanism then lowers to chuck the wafer, takes it up, and finally slides to strike the lower end of the wafer against the top end of the pole 6, thereby reducing the amount of the liq. carried with the wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate cleaning apparatus and cleaning method in which cleaning liquid is prevented from being taken out.

Semiconductor substrates include a single semiconductor typified by silicon (Si) and a compound semiconductor typified by gallium arsenide (GaAs). In each case, a single crystal ingot purified by a pulling method or the like is used. After slicing to a thickness of about μm, surface polishing and cleaning are performed to form a crystal plane with few defects in terms of crystallography, and semiconductor devices can be formed using this semiconductor substrate (wafer for short). Has been done.

[0003]

2. Description of the Related Art In most cases, semiconductor devices are mass-produced, but especially, the formation of integrated circuits using Si wafers is mass-produced.

A conventional cleaning technique will be described below by taking an Si wafer used for forming an integrated circuit as an example. Silicon dioxide (SiO ₂ ) is a material having a high insulation resistance and excellent heat resistance, and is subjected to heat treatment in the atmosphere or vapor phase growth method (abbreviated as C).
It can be formed relatively easily by the VD method).
O ₂ is dissolved in an aqueous solution of hydrofluoric acid (HF), but Si is not dissolved. Therefore, the selective etching process is frequently used in the process of forming an integrated circuit.

For example, the fee for the earliest process
Explaining the process of forming a silicon oxide film
Heating in the air to oxidize and surface₂ Formed a film
Then, a silicon nitride (Si₃N_Four)
Make a membrane, then this Si₃N _FourDry etching the film
The field oxide film (abbreviated as LOCOS) formation area as a window
Open and dip in HF solution to expose window opening to SiO 2₂ The membrane
Dissolve and wash to expose the Si wafer, then rinse with water
Form a field oxide film by high temperature oxidation in an atmosphere containing steam
Is made.

In order to dissolve and remove the SiO ₂ film at the window opening by immersing it in an HF aqueous solution, a large number of Si is added to the HF cleaning tank.
Wafers are collectively processed. There are carrier cleaning method and carrierless cleaning method as a method of collectively cleaning a large number of Si wafers. The former is a frame body made of a material having excellent chemical resistance such as fluororesin (trade name: Teflon). A few tens of Si wafers are inserted and fixed in parallel in a container at a predetermined interval (for example, 5 mm), the frame container is immersed in the cleaning tank, and after a predetermined time has passed,
It is a method of pulling up and washing with water.

In the latter, the frame container (substrate holder) is fixedly provided at the bottom of the cleaning tank, and several tens of Si wafers are collectively inserted into this substrate holder using a chuck mechanism. The present invention relates to the latter device, which is a method of taking out, transporting to an adjacent washing / washing tank, inserting them all at once, and washing with water.

[0008]

FIG. 3 is a cross-sectional view for explaining a conventional carrierless cleaning method, in which a substrate pedestal 1 made of a material having excellent chemical resistance such as Teflon has a space in which a wafer can be inserted. Several tens of them are continuously provided at the bottom of the cleaning tank, and the Si wafers 2 are collectively inserted into or removed from the substrate pedestal 1 by using a transfer device to perform cleaning.

That is, after transferring a large number of wafers 2 held by the chuck mechanism to a cleaning tank in which the HF aqueous solution 3 circulates, the wafers 2 are simultaneously lowered into the HF aqueous solution 3 and each wafer 2 is transferred. After being attached to the substrate pedestal 1, the chuck is released to return to the position above the cleaning tank.

After cleaning with the HF solution 3 circulating in the cleaning tank for a predetermined time, the chuck mechanism again descends into the HF solution 3 to chuck the Si wafer 2. Then, after pulling up, it is conveyed to the next washing / cleaning tank, and then descends again to place it on the substrate holder of the washing / cleaning tank.
i The wafer 2 is inserted and washed with water.

In this step, in order to maintain the quality of the semiconductor device, it is necessary to keep the oxide film solubility between lots equal, and in this case, keep the HF aqueous solution concentration constant.

However, when this carrierless cleaning method is carried out, the amount of the HF aqueous solution taken out along with the Si wafer 2 after the cleaning process is large, and therefore it is necessary to frequently replenish it and keep the quality constant. Therefore, it was necessary to reduce the carry-out amount of the HF aqueous solution.

[0013]

[Means for Solving the Problems] When the Si wafer which has been cleaned is held by the chuck mechanism and lifted from the cleaning tank, the lower end of the Si wafer is brought into contact with a draining pole and then lifted up later. This can be solved by adopting a method of transporting by using.

[0014]

According to the present invention, each of the substrate pedestals is provided with a pole for draining the liquid so that the lower end of the Si wafer taken out from the cleaning liquid by the chuck mechanism is brought into contact with the substrate to improve the liquid drainage and suppress the liquid from being taken out. It is a thing.

FIG. 2 is a cross-sectional view (A) and a plan view (B) of the substrate pedestal according to the present invention, in which a drain 6 is provided at the center of the substrate pedestal 5 so as to remove the liquid. It is something to do.

That is, the substrate pedestal 5 is provided with a taper for improving the insertion of the Si wafer. A pole 6 having a height protruding from the cleaning liquid 7 is provided at the center of the substrate pedestal 5 and taken out from the cleaning liquid 7. By making the bottom edge of the Si wafer touch, it is possible to improve liquid drainage.

Here, in place of the pole 6, the board pedestal 5 is used.
A plate-like protrusion similar in shape to the above may be provided, but this should not impede the circulation of the cleaning liquid 7 so that the dissolution of the oxide film on the Si wafer becomes non-uniform. It is preferable that the pole 6 has a circular or elliptical cross section to reduce the flow resistance of the cleaning liquid.

According to the present invention, such a pole 6 is provided on the substrate pedestal 5, and when the cleaning is completed and the Si wafer is taken out by the chuck mechanism, the pole 6 is touched to cause the liquid to run out, thereby suppressing the carry-out of the liquid. Is.

[0019]

FIG. 1 is a partial sectional view of a cleaning apparatus according to the present invention and a sectional view showing a method for carrying out the method. Substrate cradle 5 according to the present invention
Is made of Teflon and has a diameter of 6 inches and a thickness of 625 μm
The Si wafers 2 are formed at a pitch of 3 mm so that 50 Si wafers 2 can be inserted and the diameter is 1 mm from the center of the substrate holder 5.
The Teflon pole 6 is provided so as to protrude from the cleaning liquid 7 by 1 cm.

The cleaning liquid is an HF aqueous solution prepared by diluting a 50% HF solution to a concentration of 1:10 and is circulated through the cleaning tank by a circulation mechanism. Then, the carrierless cleaning apparatus holds 50 6-inch Si wafers 2 by the chuck mechanism and conveys them to the top of the HF cleaning tank, and then the chuck mechanism descends into the cleaning liquid 7,
After inserting the wafer 2 into the substrate pedestal 5, the chuck is released and the wafer 2 is raised and fixed as it is, during which the Si wafer 2 is etched.

Next, the chuck mechanism descends again to chuck and lift the Si wafer 2, but at the final stage of this step, the chuck mechanism slides to move Si to the tip of the pole 6 as shown in FIG. The lower edge of the wafer 2 hits and the liquid is drained.

Next, the Si wafer 2 is transferred to a pure water cleaning tank having the same structure, similarly inserted into the substrate pedestal and washed with water, and then washed with isopropyl alcohol (abbreviated as IPA). Substitution with water is carried out and drying is carried out.

[0023]

According to the present invention, it is possible to reduce the carry-out of the treatment liquid in the cleaning treatment such as the dissolution removal of the oxide film, thereby reducing the concentration fluctuation of the treatment liquid and improving the quality of the semiconductor device. can do.

[Brief description of drawings]

FIG. 1 is a partial sectional view (A) of a cleaning apparatus according to the present invention and a sectional view (B) showing an implementation method.

FIG. 2 is a sectional view (A) and a plan view (B) of a substrate pedestal according to the present invention.

FIG. 3 is a cross-sectional view illustrating a conventional carrierless cleaning method.

[Explanation of symbols]

 1,5 Substrate pedestal 2 Si wafer 3 HF aqueous solution 6 pole 7 Cleaning solution

Claims (2)

[Claims] 1. A plurality of semiconductor substrates arranged in parallel at a predetermined interval are collectively held by a chuck mechanism, transported to a substrate pedestal installed in a cleaning tank, and inserted respectively. In a cleaning device for cleaning a substrate surface by depositing and cleaning the cleaning liquid circulating in the cleaning tank, a draining pole protruding from the cleaning liquid surface is provided on each of the substrate pedestals into which the semiconductor substrate is inserted. An apparatus for cleaning a semiconductor substrate, comprising: 2. When the semiconductor substrate after the cleaning process is held by a chuck mechanism and pulled out from the cleaning tank, the lower end of the substrate is brought into contact with a draining pole and then pulled up and conveyed. Semiconductor substrate cleaning method.