KR20070010824A - Method for etching a wafer - Google Patents

Abstract

A method for etching a wafer is provided to avoid a counterflow of chemicals and increase a replacement speed of chemicals by replacing the chemicals by a down-flow method instead of an over-flow method. A plurality of wafers are received and etched in a receptacle having etchant(S110). While the etchant is exhausted to the lower part of the receptacle, a first cleaning solution is supplied from the upper part of the receptacle to firstly clean the wafers(S120). The quantity of the supplied first cleaning solution is not less than that of the etchant. A second cleaning solution is supplied from the lower part of the receptacle to secondly clean the wafers(S130).

Description

Method for etching a wafer

1 is a view for explaining a wafer etching method according to the prior art.

2 is a schematic plan view for explaining a wafer etching apparatus according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the wafer etching apparatus based on line III-III ′ of FIG. 2.

4 is a flowchart illustrating a wafer etching method according to an exemplary embodiment of the present invention.

5 to 9 are diagrams for describing the wafer etching method of FIG. 4.

Explanation of symbols on the main parts of the drawings

110: container 112: outlet

120: first cleaning liquid supply unit 122: first body

124: first nozzle 130: valve

140: second cleaning liquid supply unit 142: first body

144: first nozzle 150: support

W: Wafer

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a wafer etching method for removing the film quality of the wafer.

In general, a semiconductor device includes a Fab process for forming an electrical circuit including electrical elements on a silicon wafer used as a semiconductor wafer, and an EDS (electrical) for inspecting electrical characteristics of the semiconductor devices formed in the fab process. die sorting) and a package assembly process for encapsulating and individualizing the semiconductor devices with an epoxy resin.

The fab process includes a deposition process for forming a film on a wafer, a chemical mechanical polishing process for planarizing the film, a photolithography process for forming a photoresist pattern on the film, and the photoresist pattern using the photoresist pattern. An etching process for forming the film into a pattern having electrical characteristics, an ion implantation process for implanting specific ions into a predetermined region of the wafer, a cleaning process for removing impurities on the wafer, and a process for forming the film or pattern Inspection process for inspecting the surface;

The etching process is largely divided into a dry etching and a wet etching process. The dry etching process etches thin films in a highly reactive plasma environment, and the wet etching process etches thin films by exposing the thin films to highly reactive chemicals. The dry etching process has an advantage in that any thin film can be patterned because the thin film is etched in a plasma environment formed by dissociating a reactive gas that is likely to be plasma. In contrast, the wet etching process, unlike the dry etching process, performs the etching of the thin film using a liquid chemical that selectively etches only a specific thin film.

In general, an anisotropic dry etching process is performed to form a fine pattern, and a wet etching process is performed to remove unnecessary film material, etch the entire surface, and high select etching of different materials.

In the wafer etching process using the wet etching, chemicals and pure water are sequentially supplied to the wafers to remove the film of the wafer and at the same time, drying and the like are performed.

1 is a view for explaining a wafer etching method according to the prior art.

Referring to FIG. 1, a wafer etching process using the wafer etching apparatus 1 will be briefly described. First, a chemical supply unit (not shown) supplies chemicals to a container 10 to etch a thin film on the surface of a wafer W. Referring to FIG. Next, pure water is supplied from the pure water supply unit 20 provided on the bottom surface of the container 10. As the pure water overflows, the chemical in the container 10 is replaced with pure water, and the wafer W is cleaned by the pure water. Thereafter, the wafer W is dried.

However, the etching method as described above replaces the chemical and the pure water using an overflow method. When the pure water overflows, a phenomenon of flowing back in the center of the container 10 appears, and it takes a long time to replace the pure water and the chemical. Therefore, since the chemical continues to etch the thin film of the wafer W while pure water and chemical are replaced, the etching uniformity of the wafer W is adversely affected. In particular, as the pattern of the semiconductor device is highly integrated and the size of the wafer W is increased, the etching uniformity of the wafer W is greater.

An object of the present invention for solving the above problems is to provide a wafer etching method that can improve the etching uniformity of the wafer.

According to a preferred embodiment of the present invention for achieving the object of the present invention, the wafer etching method by receiving a plurality of wafers in the container containing the etching liquid and the first cleaning, while discharging the etching liquid to the lower portion of the container The first cleaning liquid is supplied from the top of the vessel to perform the first cleaning.

In the wafer etching method, second cleaning may be performed by supplying a second cleaning liquid from a lower portion of the container.

In the first cleaning, the supply flow rate of the first cleaning liquid is preferably equal to or greater than the discharge flow rate of the etching liquid. In addition, the etching solution is a chemical for etching the thin film of the wafer, the first cleaning liquid and the second cleaning liquid is preferably deionized for cleaning the etching liquid remaining on the wafer.

The wafer etching method according to the present invention configured as described above cleans the wafer using a downflow method in which the first cleaning liquid is supplied from the upper portion of the container while the etching liquid is discharged to the lower portion of the container. Therefore, it is possible to prevent the backflow phenomenon during the substitution of the etching solution and the first cleaning solution, and to shorten the time required for the replacement. Therefore, the thin film of the wafer can be etched uniformly, and the thin film of the wafer can be prevented from being excessively etched.

Hereinafter, a wafer etching method according to a preferred embodiment of the present invention with reference to the accompanying drawings will be described in detail.

2 is a schematic plan view illustrating a wafer etching apparatus according to an exemplary embodiment of the present invention, and FIG. 3 is a cross-sectional view of the wafer etching apparatus based on the line III-III ′ of FIG. 2.

2 and 3, the wafer etching apparatus 100 includes a container 110, a first cleaning solution supply unit 120, a valve 130, a second cleaning solution supply unit 140, and a support base 150.

The container 110 is a hollow rectangular parallelepiped with an open top. The container 110 stores an etching liquid for etching the wafer W and a cleaning liquid for cleaning the wafer W. Chemical is used as the etchant, and deionized water (DIW) is used as the cleaning solution.

The chemical etches a thin film of the wafer (W). The chemicals include APM (NH ₄ OH / H ₂ O ₂ / H ₂ O), SPM (H ₂ SO ₄ / H ₂ O ₂ ), DHF (HF / DIW), a mixture of ozone water and hydrofluoric acid (O ₃ / HF), HPM (SC-2 = Standard Clean-2, a mixture of hydrochloric acid and hydrogen peroxide and water), BHF (mixture of hydrofluoric acid and ammonium fluoride), phosphoric acid (H3PO4), HF / HNO3, potassium hydroxide (KOH), and the like. . In more detail, the oxide film SiO 2 is etched with DHF, BHF, or the like. The nitride film (Si ₃ N ₄ ) and the oxynitride film (SiON) are etched with phosphoric acid, DHF, or the like. The silicon film (Poly-Si) is etched with HF / HNO 3, potassium hydroxide (KOH), or the like. The aluminum film Al (Si) Cu is etched with a mixed acid. The cobalt film Co is etched with a mixed acid, HPM, or the like. The titanium film Ti is etched by SPM, APM, or the like.

The pure water is for cleaning the chemical remaining on the surface of the wafer W after etching the wafer W.

In the center of the bottom surface of the container 110 is provided with a discharge port 112 for the rapid discharge of the chemical or pure water. The bottom of the container 110 has an inclination toward the center where the outlet 112 is formed. Therefore, the chemical or the pure water can be easily discharged through the outlet 112.

The valve 130 is provided at the outlet 112. The valve 130 opens and closes the outlet 112.

In addition, the container 110 accommodates a plurality of wafers (W) for etching. The wafers W are disposed in the container 110 in the vertical direction, respectively.

The support 150 supports the wafers W in the container 110. The support 150 extends along the longitudinal direction of the cuboid-shaped container 110. That is, the support 150 extends in a direction crossing the wafers W disposed in the vertical direction. The support 150 has a plurality of slots for accommodating the wafers W, respectively. The support 150 may be connected to a lift (not shown) that raises or lowers the wafers W.

The first cleaning solution supply unit 120 is provided in plurality on the bottom surface of the container (110). The first cleaning solution supply units 120 are preferably spaced apart from each other by a uniform interval. The first cleaning solution supply unit 120 supplies pure water from the bottom of the container 110.

The first cleaning solution supply units 120 are configured of a first body 122 and a first nozzle 124, respectively. The first body 122 has a tubular shape and is disposed to extend along the longitudinal direction of the container 110. A plurality of first nozzles 124 are formed in a line along the length direction of the first body 122. The first nozzles 124 may be formed to be spaced apart from each other by a uniform interval.

The second cleaning solution supply unit 140 is provided with a pair of upper portions of the container 110. The second cleaning solution supply units 140 are spaced apart from each other. The second cleaning liquid supply unit 140 supplies pure water from the upper portion of the container 110 toward the center of the container 110.

The second cleaning liquid supply parts 140 may include a second body 142 and a second nozzle 144, respectively. The second body 142 has a tubular shape and is disposed to extend along the longitudinal direction of the container 110. The second nozzle 144 is provided to extend in the longitudinal direction of the second body 122.

Although not shown, the second cleaning liquid supply unit 140 may be provided with a control unit for adjusting the flow rate of the pure water supplied to the container (110). As the control unit may be a flow rate control valve for adjusting the flow rate of the pure water. In addition, the upper portion of the container 110 to the etching solution supply unit for supplying the etching liquid for etching the thin film of the wafer (W) to the container 110 and for drying the wafer (W) is finished etching and cleaning The gas supply part which supplies a gas is provided.

Hereinafter, a wafer etching method using the wafer etching apparatus 100 will be described.

4 is a flowchart illustrating a wafer etching method according to an exemplary embodiment of the present invention, and FIGS. 5 to 10 are views illustrating the wafer etching method of FIG. 4.

First, referring to FIGS. 4 to 6, first, the etchant is supplied to the inside of the container 110 from the etchant supply unit. (See FIG. 5) In this case, the outlet 112 is blocked by the valve 130. And the chemical is supplied to fill the container 110. When the chemical is filled in the container 110, the lift grips a plurality of wafers W and loads them into a support 150 located inside the container 110. In this case, the support 150 is positioned so that the loaded wafers W are sufficiently immersed in the chemical. The wafers W are etched by a chemical reaction while submerged in the chemical. That is, the chemical removes the thin film on the wafer W surface (S110).

4 and 7, after the etching by the chemical is completed, pure water, which is the first cleaning liquid, is supplied from the second cleaning liquid supply units 140 provided on the container 110. While the pure water is supplied, the valve 130 is opened so that the chemical in the container 110 is discharged to the outside through the outlet 112. Therefore, the chemical inside the container 110 is replaced with pure water. At this time, the flow rate of the pure water supplied from the upper portion of the vessel 110 is adjusted to be equal to or greater than the flow rate of the chemical discharged to the lower portion of the vessel (110). Preferably, the supply flow rate of the pure water is adjusted to be equal to the discharge flow rate of the chemical. Therefore, when the chemical is replaced, the level of the cleaning liquid inside the container 110 is kept high or the same. Therefore, the wafers W inside the container 110 are not exposed to the outside air while the chemical is replaced with pure water. The pure water, which is the first cleaning liquid, flows down, and the wafers W are first cleaned. The pure water removes chemicals remaining in the wafers (S120).

As the pure water is supplied from the upper portion of the container 110 in the above, the chemical is discharged to the lower portion of the container 110, the substitution of the pure water and the chemical is made. Therefore, it is possible to prevent the backflow phenomenon occurring when the pure water and the chemical substitution by the overflow method. In addition, the substitution rate of the chemical in the downflow method is faster than the substitution rate of the chemical in the overflow method. Therefore, it is possible to prevent the etching amount from being changed according to the position of the wafer W due to the reverse flow of the chemical. In addition, it is possible to prevent excessive etching of the thin film of the wafer (W) by the rate of substitution of the chemical or slow. Therefore, the etching uniformity of the wafer W can be improved.

When the replacement of the chemical is completed, the valve 130 blocks the outlet 112 and the pure water supply from the second cleaning liquid supply parts 140 is also stopped.

4 and 8, after the first cleaning by the pure water is completed, the second cleaning liquid is supplied from the first cleaning liquid supply units 120 provided at the lower portion of the container 110. When the pure water is supplied, the pure water in the container 110 overflows. The wafers W are secondly cleaned by the overflow of the pure water. The pure water cleans the chemical remaining in the wafers W again (S130).

When the secondary cleaning by the pure water is completed, the pure water supply from the first cleaning liquid supply unit 120 is stopped.

When the etching of the wafers W by the chemical and the cleaning of the wafers W by pure water are completed, the lift unloads the plurality of wafers W from the support 150. The wafers W are exposed to the outside, and the wafers are dried by supplying gas to the exposed wafers W from the gas supply unit.

Referring to FIG. 9, the valve 130 of the container 110 is opened to discharge pure water through an outlet to complete an etching process. Thereafter, the above processes are repeated to proceed with the wafer etching process.

As described above, the wafer etching method replaces the chemical using a downflow method, thereby shortening the time required for the replacement and preventing backflow of the chemical. Therefore, the wafers W may be uniformly etched.

Although only the method of etching the wafers W has been described above, the wafer etching method may be equally applied to a wet cleaning process for removing foreign substances remaining on the wafer W surface.

As described above, the wafer etching method according to the preferred embodiment of the present invention substitutes the chemical by using the down flow method rather than the overflow method. Therefore, it is possible to prevent backflow of the chemical and to increase the substitution rate of the chemical. Therefore, since the wafers W can be uniformly cleaned, the cleaning uniformity of the wafer can be improved.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (5)

Receiving and etching a plurality of wafers in a container containing an etchant; And And first cleaning the wafers by supplying a first cleaning liquid from the upper part of the container while discharging the etching liquid to the lower part of the container. The method of claim 1, wherein in the cleaning step, And the supply flow rate of the first cleaning solution is equal to or greater than the discharge flow rate of the etching solution. The method of claim 1, further comprising supplying a second cleaning liquid from the bottom of the container to perform second cleaning of the wafers. The wafer of claim 3, wherein the etchant is a chemical for chemically cleaning the wafer, and the first and second cleaning solutions are deionized for cleaning the etchant remaining on the wafers. Etching method. The wafer etching method of claim 3, wherein the second cleaning comprises cleaning while the second cleaning liquid overflows.

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