Wet cleaning apparatus and methods

Abstract

Apparatus for wet cleaning is disclosed. In one example, such an apparatus includes first and second Sulfuric Acid Peroxide Mixture (SPM) baths for removing photoresist on semiconductor wafers that are sequentially provided; a Hot Quick Dump Rinse (HQDR) bath for cleaning the wafers conveyed from the first and second baths; first and second Ammonium Peroxide Replacement (APR) baths for cleaning particles and organic residues remaining on the wafers conveyed from the HQDR bath; and a drier for drying the wafers conveyed from the first and second APR bath.

Description

TECHNICAL FIELD

The present disclosure relates to semiconductor fabrication technology and, more particularly, to wet cleaning apparatus and methods.

BACKGROUND

Generally, semiconductor integrated circuit (IC) chips are fabricated by subjecting a silicon wafer to sequential and repeated processes of photo, etch, ashing, ion diffusion, and thin-film deposition processes.

In this wafer fabrication process, the photo process includes: a deposition step of photoresist having optical sensitivity on the surface of the wafer; a step for placing a reticle having circuit patterns to be manufactured in the wafer; an exposure step for transferring the circuit patterns of the reticle to the deposited photoresist by irradiating the wafer with light having a predetermined wavelength; and a development step for developing the exposed photoresist to form the circuit patterns in the wafer.

In the photo process, some portions of layers underlying the photoresist are etched and removed using the photoresist pattern that remains after the development process, and then remaining photoresist pattern is removed by an ashing step.

The ashing step can be divided into two steps: a wet ashing step in which chemicals are used in the removal of the patterned photoresist; and a dry ashing set in which a predetermined ashing gas such as plasma and ozone is used to expunge the patterned photoresist.

FIG. 1 shows known wet cleaning equipment such as post-ashing equipment performing the wet ashing process and post-treatment equipment performing SH cleaning after the Chemical Mechanical Polishing (CMP).

Referring to FIG. 1, the conventional wet cleaning equipment comprises a Sulfuric Acid Peroxide Mixture (SPM) bath 102, a Chuck/Clean (C/C) 104, a Hot Quick Dump Rinse (HQDR) bath 106, an Ammonium Peroxide Replacement (APR) bath 108, and drier 110. In the conventional equipment, the SPM bath 102 contains mixture of H₂SO₄ and H₂O₂ (SPM), the C/C 104 is for cleaning a robot chuck that carries wafers, and the APR bath 108 is to clean particles and organic residues remaining on the wafer.

Further, the APR bath 108 is structured as a single bath type by which two processes for chemical treatment and rinse are conducted simultaneously. In order to perform the necessary processes with the APR bath 108, it a tank 108′ is needed to mix an alkali chemical, H₂O₂ and hot Deionized Water (DIW). The mixture 112 is heated to 70° C., and is then provided from the tank 108′ to the APR bath 108.

With the conventional equipment having the structure explained above, the conventional wet cleaning process is performed in the order of SPM cleaning step→HQDR cleaning step→APR cleaning step→dry step. This process normally takes about 38 minutes in these steps per single arrangement of equipment. That is, the throughput time of the conventional wet cleaning process per equipment is about 38 minutes.

For reducing the processing time and improving the throughput, investment in additional equipment is necessary. However, such purchases increase fabrication cost.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of conventional wet cleaning equipment.

FIG. 2 is a schematic diagram of example disclosed wet cleaning equipment.

DETAILED DESCRIPTION

Disclosed herein are a wet cleaning apparatus and cleaning methods adapted to be used in post-ashing equipment that is employed in removing photoresist.

As shown in FIG. 2, an APR bath which has significant effect on the throughput time is provided additionally, a capacity of a tank for providing mixed solution to the APR bath is increased, and an SPM bath is added, so that the overall throughput time is cut in half when compared with the throughput time of the conventional equipment.

Referring to FIG. 2, one example of disclosed wet cleaning equipment includes first and second SPM bath 12a and 12b, a C/C 14, a HQDR bath 16, first and second APR baths 18a and 18b, a tank 18′, and a drier 20. The tank 18′ mixes alkali chemical, H₂O₂ and DIW. Further, the tank 18′ heats the mixed solution 22 to a processing temperature, and provides the heated mixed solution to the first and second APR baths 18a and 18b.

The tank 18′ has an increased capacity to accommodate the addition of the APR bath by making, for example, the capacity of the deionized water to be 24 liters and the power of the heater to be 24 kilowatts (KW), as compared with the conventional tank (108′ of FIG. 1) of 18 liters of deionized water capacity and 12 KW power of heater. With this structure of the tank 18′, time in preparing for the mixed solution to be provided to the first and second baths 18a and 18b is cut in half in comparison with the conventional equipment. For instance, the time for the preparation is reduced to about less than 15 minutes by disclosed example.

Now, the method for cleaning by using the wet cleaning equipment is explained.

A wafer cassette (hereinafter ‘first wafer cassette’) having a number of wafers that have patterned circuits formed by the photo process is loaded and conveyed by a loader to the first SPM bath 12a where H₂SO₄ and H₂O₂ is mixed by a predetermined weight ratio (for example, 6:1) to be subjected to the photoresist removal process.

During the process for removing the photoresist is performed, another wafer cassette (hereinafter ‘second wafer cassette’) is loaded to the second SPM bath 12b, and the photoresist patterned on the second wafers are removed.

The loading of the first and second wafer cassette to the first and second SPM baths 12a and 12b is conducted with a predetermined time difference.

The first wafer cassette, after the removal of photoresist at the first SPM bath 12a, is transferred to the HQDR bath 16 for the wafer cleaning process, and then conveyed to the first APR bath 18a that contains alkali chemical (e.g., ammonia (NH₄OH)), H₂O₂, and DI water of a predetermined weight ratio of, for example 0.2:1:10 to be subjected to cleaning particles and organic residues and drying in the drier 20.

When the first wafer cassette is conveyed to the first APR bath 12a, the second wafer cassette is moved to the HQDR bath 16 for cleaning. The subsequent processing of the second wafer cassette is the same as conducted for the first wafer cassette.

By using the disclosed processing, the time consumed by cleaning wafers of a wafer cassette is reduced to less than 20 minutes, which amounts to about a half of the conventional time.

Disclosed herein are methods and apparatus for wet cleaning that can reduce the throughput time and prevent increased equipment investment.

According to one particular example, wet cleaning equipment may include first and second Sulfuric Acid Peroxide Mixture (SPM) baths for removing photoresist on semiconductor wafers that are sequentially provided; a Hot Quick Dump Rinse (HQDR) bath for cleaning the wafers conveyed from the first and second baths; first and second Ammonium Peroxide Replacement (APR) baths for cleaning particles and organic residues remaining on the wafers conveyed from the HQDR bath; and a drier for drying the wafers conveyed from the first and second APR bath. In one example, the first and second baths include a tank that heats a mixed solution of alkali chemicals, H₂O₂, and deionized water to a processing temperature and provides the heated mixed solution to the first and second APR baths.

One example disclosed method includes using first and second SPM baths, a HQDR bath, and first and second baths. The first plurality of wafers in a first wafer cassette are cleaned by passing through the first SPM bath, the HQDR bath and the first APR bath, while second plurality of wafers in a second wafer cassette are cleaned by passing through the second SPM bath, the HQDR bath and the second APR bath.

Although certain apparatus constructed in accordance with the teachings of the invention have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers every apparatus, method and article of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.

Claims

1. An apparatus for performing removal of photoresist and SH cleaning, comprising:

first and second Sulfuric Acid Peroxide Mixture (SPM) baths to remove photoresist on semiconductor wafers that are sequentially provided;

a Hot Quick Dump Rinse (HQDR) bath to clean the wafers conveyed from the first and second SPM baths;

first and second Ammonium Peroxide Replacement (APR) baths to clean particles and organic residues remaining on the wafers conveyed from the HQDR bath; and

a drier to dry the wafers conveyed from the first and second APR baths.

2. An apparatus as defined by claim 1, further including a tank that heats a mixed solution of alkali chemicals, H2O2 and deionized water to a processing temperature and provides the heated mixed solution to the first and second APR baths.

3. A method for wet cleaning by using first and second SPM baths and a HQDR bath, wherein first plurality of wafers in a first wafer cassette are cleaned by passing through the first SPM bath, the HQDR bath and the first APR bath, while second plurality of wafers in a second wafer cassette are cleaned by passing through the second SPM bath, the HQDR bath and the second APR bath.