JP2003318154A - Method and device for etching substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily flatten the surface of a substrate by using an etchant. <P>SOLUTION: When, for example, a copper film 4 formed on the surface of the substrate W has an inclined surface that is inclined downward as getting nearer to the peripheral edge section from the central part, the etchant is supplied to the central part of the substrate W from an etchant nozzle 2 and, at the same time, a suppressive liquid for etching is supplied to the peripheral edge section of the copper film 4 from a suppressive liquid nozzle 3 while the substrate W is rotated by means of a spin chuck 1. At this time, the supplied position of the suppressive liquid for etching from the nozzle 3 is moved by oscillating a scanning arm 31. In addition, the oscillating speed (scanning speed) of the scanning arm 31 is made faster as the supplied position of the suppressive liquid for etching approaches the central part of the substrate W and slower as the supplied position approaches the peripheral edge section of the substrate W. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for etching a substrate by supplying an etching solution to the surface of the substrate. Substrates to be processed include semiconductor wafers, glass substrates for liquid crystal display devices, glass substrates for plasma displays, optical disc substrates, magnetic disc substrates, magneto-optical disc substrates, photomask substrates, and the like.

[0002]

2. Description of the Related Art For example, the step of forming fine wiring on the surface of a substrate includes the step of flattening the surface of a metal wiring film formed on the substrate. A typical technique for this flattening is C
MP (Chemical Mechanical Polishing) treatment can be mentioned, but recently, as an alternative technique to the CMP treatment, ECMD (El
ectro Chemical Mechanical Deposition) technology is drawing attention. In this method, flattening is simultaneously performed while forming (plating) a metal wiring film on the substrate surface. For example, it is realized by flattening the substrate surface with a pad during the plating process, or by accelerating the growth rate of plating at the bottom (bottom) of the wiring pattern as compared with the surface (top) of the wiring pattern.

However, with such a technique, the surface of the metal wiring film cannot be satisfactorily flattened, and some unevenness remains on the surface of the metal wiring film even after the processing. Therefore, an object of the present invention is to provide a substrate etching method and a substrate etching apparatus capable of satisfactorily flattening the surface of a substrate using an etching solution.

[0004]

In order to achieve the above-mentioned object, the invention according to claim 1 is to rotate the substrate about an axis of rotation substantially orthogonal to the substrate (W) while A substrate etching method for supplying an etching liquid to the surface to perform an etching treatment on the substrate surface, wherein the etching liquid is supplied toward a predetermined position on the substrate surface, and a position farther from the rotation axis than the predetermined position. The method for etching a substrate is characterized by including a selective etching step of supplying an etching inhibitor for suppressing the etching of the surface of the substrate by the etching liquid.

The alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same applies in this section below. According to the above method, the etching with the etching solution proceeds at a predetermined position on the surface of the substrate, and the etching with the etching solution is suppressed in the other regions by the action of the etching suppression solution. Accordingly, when the thickness of the film (4) formed on the substrate is not constant, if the portion having a large film thickness is set at the above-mentioned predetermined position, the etching proceeds at the portion having a large film thickness, The progress of etching can be suppressed in a small portion, and as a result, the surface of the film can be flattened.

According to a second aspect of the present invention, the etching inhibitor contains at least one of pure water, carbonated water, ionic water, reduced water (hydrogen water) and a corrosion inhibitor. Good. According to a third aspect of the present invention, in the selective etching step, the etching solution is supplied to a region including a rotation center of the substrate, and the etching suppression liquid is supplied to a region from a peripheral portion to a central portion of the substrate. The method for etching a substrate according to claim 1 or 2, wherein:

When the film thickness of the film formed on the substrate is large in the region including the center of rotation of the substrate and small in the region from the peripheral portion to the central portion of the substrate, the method according to claim 3 The surface of the film can be flattened well. Note that, as described in claim 4, the supply position of the etching suppressing liquid may be moved within a region from the peripheral portion to the central portion of the substrate. In this case, as described in claim 5, the speed at which the etching-suppressing liquid supply position moves along the peripheral portion of the substrate is lower than the speed at which the etching-suppressing liquid supply position moves at the central portion of the substrate. You may set it. According to the method of claim 5, when the film formed on the surface of the substrate is thicker in the central portion than in the peripheral portion and the surface of the film is formed in an inclined surface which is inclined downward as it approaches the peripheral portion. Since the surface of the film can be flattened well,
Especially effective.

The movement direction of the supply position of the etching inhibitor may be a direction along the radial direction of rotation of the substrate.
Further, as described in claim 6, the flow rate of the etching suppressing liquid supplied to the peripheral portion of the substrate may be set higher than the flow rate of the etching suppressing liquid supplied to the central portion of the substrate. The method according to claim 6 is also particularly effective when the film formed on the surface of the substrate is thicker in the central portion than in the peripheral portion and the surface of the film is formed into an inclined surface inclined toward the peripheral portion. Is.

According to a seventh aspect of the present invention, in the selective etching step, the etching liquid is supplied to a predetermined position on a region deviated from the rotation center of the substrate, and the etching liquid is provided at a position farther from the rotation axis than the predetermined position. 7. The method for etching a substrate according to claim 1, which is a step of supplying the etching suppressing liquid. 8. When the film thickness of the film formed on the substrate is larger than other portions at a predetermined position on the region off the center of rotation of the substrate,
By the method described, the surface of the film can be satisfactorily flattened.

According to an eighth aspect of the present invention, the substrate etching method further includes a non-selective etching step of stopping the supply of the etching suppressing liquid and supplying the etching liquid to a region including the rotation center of the substrate. The method for etching a substrate according to any one of claims 1 to 7, which is characterized. According to this method, the etching liquid supplied to the region including the rotation center of the substrate in the non-selective etching process receives the centrifugal force due to the rotation of the substrate and evenly spreads over the entire surface of the substrate, and Is subjected to a substantially uniform etching process.

Therefore, for example, as described in claim 9, by performing the non-selective etching step after the selective etching step, a film on the surface of the substrate planarized by the selective etching step is desired. The film thickness can be adjusted. When a plurality of undulations (4a, 4b) are formed on the surface of the substrate due to partial differences in the thickness of the film formed on the surface of the substrate, as described in claim 10. By performing the non-selective etching step after performing the selective etching step a plurality of times, it is possible to obtain a substrate having a film having a desired film thickness whose surface is flattened.

According to an eleventh aspect of the present invention, there is provided a substrate rotating means (1) for rotating the substrate around a rotation axis substantially orthogonal to the substrate (W), and a predetermined position on the surface of the substrate rotated by the substrate rotating means. And an etching liquid nozzle (2) for supplying the etching liquid toward the substrate, and when the etching liquid is supplied by the etching liquid nozzle, the etching liquid is directed toward a position farther from the rotation axis than the predetermined position on the surface of the substrate. A substrate etching apparatus comprising: a suppressing liquid nozzle (3) for supplying an etching suppressing liquid for suppressing etching of a substrate surface.

According to the present invention, it is possible to obtain the same effect as that described in relation to claim 1.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of a substrate etching apparatus according to an embodiment of the present invention. This substrate etching apparatus forms a copper film over the entire surface of the substrate W in the step of patterning copper wiring on the surface of the substrate W such as a semiconductor wafer or a glass substrate for a liquid crystal display device, and then removes the formed copper film. A spin chuck 1 for holding the substrate W horizontally and rotating it in a processing chamber partitioned by partition walls, and a substrate W held by the spin chuck 1 for performing a process of flattening the surface. An etching liquid nozzle 2 for supplying an etching liquid to the upper surface of the substrate, and a suppressing liquid nozzle 3 for supplying an etching suppressing liquid to the upper surface of the substrate W held by the spin chuck 1.

The spin chuck 1 is, for example, a spin shaft 11 extending in the vertical direction, a spin base 12 attached to the upper end of the spin shaft 11, and a plurality of chucks arranged on the periphery of the spin base 12. 13 and 13. The plurality of chucks 13 are configured to contact the peripheral portion of the substrate W and hold the substrate W in a horizontal state. A rotation driving mechanism 14 including a driving source such as a motor is coupled to the spin shaft 11, and a driving force is applied from the rotation driving mechanism 14 to the spin shaft 11 while the substrate W is held horizontally by the chuck 13. By inputting, the substrate W can be rotated in a horizontal plane.

An etching liquid supply pipe 21 is connected to the etching liquid nozzle 2, and the etching liquid is supplied from the etching liquid supply pipe 21.
A valve 22 for opening and closing the etching liquid supply pipe 21 is provided in the middle of the etching liquid supply pipe 21. In this embodiment, the etching solution nozzle 2 is fixedly arranged in the processing chamber, and by opening the valve 22, the etching solution supplied from the etching solution supply pipe 21 is transferred to the substrate W held on the spin chuck 1. It is possible to feed it toward almost the center of the surface.

The suppressing liquid nozzle 3 is attached to a scan arm 31 extending substantially horizontally above the spin chuck 1. The scan arm 31 is swingably provided around a vertical axis set outside the substrate W held by the spin chuck 1, and by the swing of the scan arm 31, the scan arm 31 is moved from the suppression liquid nozzle 3 to the substrate W. The supply position of the etching suppressing liquid to the substrate W can be moved (scanned) in the radial direction of rotation of the substrate W within a range from the peripheral portion to the central portion of the substrate W, for example. The suppression liquid supply pipe 32 is connected to the suppression liquid nozzle 3.
The etching suppressing liquid is supplied from here.
A valve 33 for opening and closing the suppression liquid supply pipe 32 is provided in the middle of the suppression liquid supply pipe 32.

The etching suppressing liquid is a liquid having an effect of suppressing etching by the etching liquid, and is, for example, pure water, carbonated water, ionic water, reduced water (hydrogen water) or a corrosion inhibitor (for example, BTA: benzotriazole). )
Can be used. FIG. 2 is a schematic sectional view for explaining an example of the operation of this substrate etching apparatus. For example, as shown in FIG. 2A, when the copper film 4 formed on the surface of the substrate W is thicker in the central portion than in the peripheral portion and a step is formed between the central portion and the peripheral portion, While the substrate W is being rotated in the horizontal plane by the spin chuck 1, the etching liquid nozzle 2 is provided at the center of the rotating substrate W.
While supplying the etching solution from the suppressing solution nozzle 3 to the step portion formed on the copper film 4 (substrate W).

As a result, the central portion of the copper film 4 is etched by the etching liquid from the etching liquid nozzle 2, and the peripheral portion of the copper film 4 is suppressed by the etching suppressing liquid from the suppressing liquid nozzle 3. , The surface of the copper film 4 becomes almost flat. Then, after the surface of the copper film 4 becomes substantially flat, the valve 33 interposed in the suppression liquid supply pipe 32 is closed, and the supply of the etching suppression liquid from the suppression liquid nozzle 3 is stopped to a predetermined level. Only the supply of the etching liquid from the etching liquid nozzle 2 is continued for a time. as a result,
As shown in FIG. 2B, it is possible to obtain a copper film 4 having a desired film thickness and a flat surface.

The supply time of the etching solution from the etching solution nozzle 2 and the supply time of the etching suppression solution from the suppression solution nozzle 3 are respectively the copper film 4 before the treatment.
The thickness of the central portion of the copper film 4 before the treatment may be determined according to the thickness of the central portion of the copper film 4 and the desired thickness of the copper film 4 after the treatment. It can be known by measuring it. Further, the stepped portion on the copper film 4 to which the etching suppressing liquid from the suppressing liquid nozzle 3 should be supplied can be specified from the measurement result.

FIG. 3 is a schematic sectional view for explaining another example of the operation of this substrate etching apparatus. For example, as shown in FIG. 3 (a), the copper film 4 formed on the surface of the substrate W is thicker in the central portion than in the peripheral portion, and is formed in an inclined surface that is inclined downward as the surface approaches the peripheral portion. In this case, the etching liquid is supplied from the etching liquid nozzle 2 to the central portion of the substrate W being rotated by the spin chuck 1, while the suppressing liquid nozzle 3 is applied to the peripheral portion of the copper film 4 (substrate W). Supply an etching inhibitor. that time,
The scan arm 31 is swung to move the supply position of the etching suppressing liquid from the suppressing liquid nozzle 3. In addition, the speed at which the scan arm 31 swings (scan speed) is
The etching suppression liquid is set to be closer to the central portion of the substrate W, and the etching suppression liquid is set to be closer to the peripheral portion of the substrate W.

As a result, the copper film 4 is etched at a higher etching rate as it approaches the central portion and at a lower etching rate as it approaches the peripheral portion. Then, when the treatment progresses to a certain extent, the surface of the copper film 4 becomes substantially flat, and thereafter, the valve 33 interposed in the suppression liquid supply pipe 32 is closed to remove the etching suppression liquid from the suppression liquid nozzle 3. By stopping the supply and continuing only the supply of the etching liquid from the etching liquid nozzle 2 for a predetermined time, as shown in FIG. 3 (b), the copper film 4 having a desired film thickness whose surface is flattened is formed. Obtainable.

The moving speed of the scan arm 31 does not necessarily have to be changed, and the scan arm 31 may be swung at a constant speed. Substrate W
When the etching suppressing liquid is supplied to a position near the center of the scanning arm 31, the supplied etching liquid flows toward the peripheral portion due to the centrifugal force due to the rotation of the substrate W, so that the scan arm 31 is swung at a constant speed. Even when it is set, the supply amount of the etching suppressing liquid increases as it gets closer to the peripheral edge of the substrate W, and the copper film 4 is etched at a higher etching rate as it gets closer to the central portion and gets smaller as it gets closer to the peripheral edge. Etched at a rate.

FIG. 4 is a schematic sectional view for explaining the operation of the substrate etching apparatus according to another embodiment of the present invention. In the substrate etching apparatus according to this embodiment, the etching liquid nozzle 2 and the suppression liquid nozzle 3 are attached to different scan arms that do not interfere with each other, and the etching liquid and the etching suppression liquid are respectively fed from the rotation axis of the substrate W. The copper film 4 is formed on the substrate W so that it can be supplied to a position at an arbitrary distance.
Even when has a plurality of undulations, the copper film 4 can be satisfactorily flattened.

In processing the substrate, first, the position of the undulations formed on the surface of the copper film 4 is specified using a known film thickness measuring device. For example, as shown in FIG. 4 (a), the copper film 4 has a plurality of concentric (rotationally symmetric) undulations 4a, 4b.
In such a case, the etching solution is supplied from the etching solution nozzle 2 to the top of one of the undulations 4a, and the etching solution is supplied from the suppression solution nozzle 3 to a position farther from the supply position of the etching solution with respect to the rotation center of the substrate W. Supply. As a result, the undulations 4a are removed by etching with the etching liquid. Subsequently, as shown in FIG. 4 (b), the etching liquid is supplied from the etching liquid nozzle 2 to the top of the other undulating portion 4b, and the etching liquid is supplied to a position farther from the supply position of the etching liquid with respect to the rotation center of the substrate W. Suppression liquid nozzle 3
By supplying the etching suppression liquid from the
b is removed by etching. Then, when the undulations 4b are removed and the surface of the copper film 4 becomes substantially flat, thereafter, the valve 33 interposed in the suppression liquid supply pipe 32 is closed,
The supply of the etching suppressing liquid from the suppressing liquid nozzle 3 is stopped, and only the supply of the etching liquid from the etching liquid nozzle 2 is continued for a predetermined time. As a result, as shown in FIG. 4C, the copper film 4 having a desired film thickness and having a flat surface can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above-described embodiment, the case where the copper film formed on the surface of the substrate W is flattened by etching has been taken up, but the target of flattening is not limited to the copper film, but may be a tungsten film or an aluminum film. It may be another metal film or an oxide film other than the metal film. Further, in particular, when the copper film 4 formed on the surface of the substrate W is thicker in the central portion than in the peripheral portion and the surface is formed in an inclined surface that is inclined downward as it approaches the peripheral portion, the scan arm 31 By shaking the suppression liquid nozzle 3
When moving the supply position of the etching suppressor from above the region where the copper film is thinly formed, the flow rate of the etching suppressor discharged from the suppressor nozzle 3 is set to It may be possible to suppress the progress of etching in the peripheral portion of the substrate W by decreasing the amount toward the edge portion and increasing the supply position of the etching suppressing liquid toward the peripheral portion of the substrate W. At this time, the speed at which the scan arm 31 oscillates (scan speed) may be constant, or the supply position of the etching suppressing liquid may be changed to the substrate W.
May be set closer to the central portion of the substrate W, and may be set closer to the peripheral portion of the substrate W, and may be set later.

In addition, various design changes can be made within the scope of the matters described in the claims.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a substrate etching apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a process when a copper film formed on a surface of a substrate is thicker in a central portion than a peripheral portion and a step is formed between the central portion and the peripheral portion. Is.

FIG. 3 is a view for explaining a process when the copper film formed on the surface of the substrate is thicker in the central portion than in the peripheral portion and is formed on an inclined surface inclined downward as the surface approaches the peripheral portion. It is a schematic sectional drawing.

FIG. 4 is a schematic sectional view for explaining a process when a plurality of undulations are formed on the surface of a copper film formed on the surface of a substrate.

[Explanation of symbols]

1 spin chuck 2 Etching liquid nozzle 3 suppression liquid nozzle 4 Copper film 4a undulations 4b undulation W board

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiji Iwata             4 Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto City, Kyoto Prefecture             No. 1 at Tenjin Kitamachi             Manufacturing Co., Ltd. F term (reference) 5F043 DD13 EE07 EE08 EE27 EE40                       FF07 GG02

Claims (11)

[Claims] 1. A method for etching a substrate, which comprises etching a substrate surface by supplying an etching solution to the surface of the substrate while rotating the substrate about an axis of rotation substantially orthogonal to the substrate. A selective etching step of supplying an etching solution for controlling the etching of the substrate surface by the etching solution toward a position farther from the rotation axis than the predetermined position. A method for etching a substrate, comprising: 2. The etching suppressing liquid is pure water, carbonated water,
The substrate etching method according to claim 1, further comprising at least one of ionized water, reduced water, and a corrosion inhibitor. 3. The selective etching step is a step of supplying the etching solution to a region including a rotation center of the substrate and supplying the etching suppressing liquid to a region from a peripheral portion to a central portion of the substrate. The substrate etching method according to claim 1 or 2, which is characterized in that. 4. The substrate etching method according to claim 3, wherein the supply position of the etching inhibitor is moved within a region from the peripheral portion to the central portion of the substrate. 5. The speed at which the etching suppression liquid supply position moves along the peripheral edge of the substrate is set to be slower than the speed at which the etching suppression liquid supply position moves at the central part of the substrate. The method for etching a substrate according to claim 4, wherein the method is for etching a substrate. 6. The flow rate of the etching suppressing liquid supplied to the peripheral portion of the substrate is set to be higher than the flow rate of the etching suppressing liquid supplied to the central portion of the substrate. Alternatively, the substrate etching method according to item 5. 7. The selective etching step supplies the etching solution to a predetermined position on an area off the center of rotation of the substrate, and supplies the etching suppressing solution to a position farther from the rotation axis than the predetermined position. 7. The method for etching a substrate according to claim 1, wherein the method is the step of performing. 8. The substrate etching method further comprises a non-selective etching step of stopping the supply of the etching suppressing liquid and supplying the etching liquid to a region including a rotation center of the substrate. 8. The substrate etching method according to any one of items 1 to 7. 9. The method of etching a substrate according to claim 8, wherein the non-selective etching step is performed after the selective etching step. 10. The substrate etching method according to claim 9, wherein the non-selective etching step is performed after the selective etching step is performed a plurality of times. 11. A substrate rotating means for rotating the substrate about an axis of rotation substantially orthogonal to the substrate, and an etching solution nozzle for supplying an etching solution toward a predetermined position on the surface of the substrate rotated by the substrate rotating means. When the etching liquid is supplied by the etching liquid nozzle, an etching suppressing liquid for suppressing the etching of the substrate surface by the etching liquid is supplied toward a position farther from the rotation axis than the predetermined position on the surface of the substrate. A substrate etching apparatus comprising: a suppressing liquid nozzle.