US20070000609A1

US20070000609A1 - Etching apparatus

Info

Publication number: US20070000609A1
Application number: US11/308,830
Authority: US
Inventors: Wei-Jen Tai; Chuan-Yi Wu; Mei-Kuei Tseng; Ming-Tan Hsu
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-30
Filing date: 2006-05-12
Publication date: 2007-01-04
Also published as: TWI255864B; TW200700584A

Abstract

An etching apparatus, for etching copper or silver, which includes a hydrogen peroxide tank, an ammonium hydroxide tank, a water tank, an etching tank, a piping system and a temperature control device, is provided. The piping system connects the hydrogen peroxide tank, the ammonium hydroxide tank, the water tank to the etching tank, and the temperature control device is disposed around the hydrogen peroxide tank, the ammonium hydroxide tank and the etching tank to maintain the temperatures of them below the room temperature and above 12 degree centigrade. An etching process is also provided. First, hydrogen peroxide and ammonium hydroxide having a temperature in a temperature-range below the room temperature and above 12 degree centigrade, is provided. Then, water, hydrogen peroxide and ammonium hydroxide are mixed to be an etchant with a temperature maintained in said temperature temperature-range. Next, the etchant is utilized for etching copper or silver.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of application Ser. No. 11/161,309, filed on Jul. 29, 2005, which claims the priority benefit of Taiwan patent application serial no. 94122059, filed Jun. 30, 2005 and is now pending. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an etching apparatus. More particularly, the present invention relates to an etching apparatus and an etching process with stable etching rate.
2. Description of Related Art
In semiconductor processing, an etching process is used to remove a thin film that is not covered by a photoresist layer or a mask layer by way of chemical reaction or physical phenomenon to transfer a pattern from a photomask to the thin film. Meanwhile, a complete removal of a thin film is often accomplished by an etching process. The current etching techniques in semiconductor processing are basically divided into wet etching and dry etching, wherein dry etching mainly relies on the electron beam to perform the etching of the thin film, and wet etching mainly relies on chemical reaction to perform the etching of the thin film.
Copper (Cu) and silver (Ag) are general used as conductive material in semiconductor elements. Copper film or silver film can be used to form a patterned conductive layer with multi-function by wet etching. When the patterned conductive layer in circuit structure, it could be the conductive wires, electrodes bonding pads and others. The etchant mixed with hydrogen peroxide (H2O2) and ammonium hydroxide (NH4OH) is often used to etch the copper film of the silver film. That is, a substrate with the copper film of the silver film formed thereon will be immersed in an etching tank filled with the etchant mixed with hydrogen peroxide and ammonium hydroxide during the etching of the copper film or the silver film. Thereafter, chemical reaction occurs between the etchant and the copper film or the silver film, and the copper film or the silver film will be etched. For example, the reaction between the etchant and the silver film is:
2Ag(s)+H2O2(aq)+2H+2Ag+→2H2O(l) (1)
4NH4OH(aq)→4NH3(aq)+4H2O(l) (2)
2Ag++4NH3(aq)→2Ag(NH3)2 (3)
and the total reaction is (1)+(2)+(3) as follow:
2Ag(s)+H2O2(aq)+2H++4NH4OH(aq)→2Ag(NH3)2+6H2O(l) (4)
General, the etching apparatus for etching silver or copper includes a hydrogen peroxide tank, an ammonium hydroxide tank, a water tank, an etching tank and a piping system, wherein the etching tank is connected to the hydrogen peroxide tank, the ammonium hydroxide tank and the water tank by the piping system. Hydrogen peroxide, ammonium hydroxide and deionized water are delivered to the etching tank by the piping system to form the etchant for etching the copper film or the silver film.
However, hydrogen peroxide, ammonium hydroxide and deionized water are delivered and mixed in the room temperature in the etching apparatus, wherein the room temperature is between 22 degree centigrade and 23 degree centigrade. Therefore, part of hydrogen peroxide and ammonium hydroxide will be influenced by the room temperature and vaporized during delivering, and the delivering pipes will be block by the bubbles formed from vaporized hydrogen peroxide and ammonium hydroxide. The suction of hydrogen peroxide and ammonium hydroxide is difficult in the blocked delivering pipes, such that the operation reliability of the conventional etching apparatus will be decreased. Moreover, hydrogen peroxide and ammonium hydroxide also influenced by the room temperature and vaporized during mixing, and the concentration of the etchant is changed consequently. Therefore, the etching rate of the etchant for copper film and silver film is unstable. Else, vaporized ammonium hydroxide produces stimulative smell.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an etching apparatus and an etching process for avoiding the block in the piping system while hydrogen peroxide and ammonium hydroxide are delivered.
The present invention is also directed to an etching apparatus and an etching process for avoiding the decrease of the concentration of the etchant in the etching tank, such that the etching rate of the etchant for copper or silver will be more stable.
The present invention is further directed to an etching apparatus and an etching process for avoiding the stimulative smell produced by vaporized ammonium hydroxide.
In order to achieve the objects mentioned above, the present invention provides an etching apparatus. The etching apparatus for etching copper or silver includes a hydrogen peroxide tank, an ammonium hydroxide tank, a water tank, an etching tank, a piping system and a temperature control device. The piping system connects the hydrogen peroxide tank, the ammonium hydroxide tank and the water tank to the etching tank. The temperature control device is disposed around the hydrogen peroxide tank, the ammonium hydroxide tank and the etching tank to maintain the temperatures of them below the room temperature and above 12 degree centigrade.
According to an embodiment of the present invention, the temperatures of the hydrogen peroxide tank, the ammonium hydroxide tank and the etching tank can be maintained among 12 degree centigrade to 18 degree centigrade.
According to another embodiment of the present invention, wherein the temperature control device can be also disposed around the water tank to maintain the temperature of the water tank below the room temperature and above 12 degree centigrade.
According to another embodiment of the present invention, wherein the temperature control device can be also disposed around the piping system to maintain the temperature of the piping system below the room temperature and above 12 degree centigrade.
According to an embodiment of the present invention, the etching apparatus further includes a buffer tank disposed between the hydrogen peroxide tank, the ammonium hydroxide tank, the water tank and the etching tank, and the hydrogen peroxide tank, the ammonium hydroxide tank and the water tank are connected to the buffer tank through the piping system, and the buffer tank is also connected to the etching tank through the piping system.
According to an embodiment of the present invention, wherein the temperature control device can be also disposed around the buffer tank to maintain the temperature of the buffer tank below the room temperature and above 12 degree centigrade.
According to an embodiment of the present invention, the etching apparatus further includes a pump connected to the piping system.
According to an embodiment of the present invention, the etching apparatus further includes a flow meter disposed in the piping system between the hydrogen peroxide tank, the ammonium hydroxide tank, the water tank and the etching tank.
In order to achieve the objects mentioned above, the present invention further provides an etching process. The first step of the etching process is providing hydrogen peroxide and ammonium hydroxide, wherein the temperatures of hydrogen peroxide and ammonium hydroxide are maintained within a temperature-range below the room temperature and above 12 degree centigrade. Thereafter, mixing water, hydrogen peroxide and ammonium hydroxide to form an etchant, and the temperature of the etchant is maintained within the temperature-range below the room temperature and above 12 degree centigrade. Afterward, etching copper or silver with the etchant.
According to an embodiment of the present invention, wherein the temperature-range is among 12 degree centigrade to 18 degree centigrade, for example.
According to an embodiment of the present invention, wherein the temperature of water could be within the temperature-range before mixing water, hydrogen peroxide and ammonium hydroxide.
According to an embodiment of the present invention, wherein the weight ratio of (hydrogen peroxide: ammonium hydroxide: water) of the etchant is (3:8:9), for example.
With the use of the temperature control device in the present invention for maintaining the temperatures of hydrogen peroxide and ammonium hydroxide below the room temperature and above 12 degree centigrade in the etching process, the block in the piping system can be avoided. Moreover, the vaporizing rates of hydrogen peroxide and ammonium hydroxide can be decreased to make the etching rate of the etchant for copper or silver more stable. Otherwise, the stimulative smell produced by vaporized ammonium hydroxide could be decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a flow chart of an etching process according to one embodiment of the present invention.
FIG. 2 is a schematic view of an etching apparatus according to one embodiment of the present invention.
FIG. 3 is a schematic view of an etching apparatus according to another one embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Referring to FIG. 1, the first step S1 of etching process 100 is providing hydrogen peroxide and ammonium hydroxide, wherein the temperatures of hydrogen peroxide and ammonium hydroxide are below the room temperature and above 12 degree centigrade. The vaporizing rates of hydrogen peroxide and ammonium hydroxide in step S1 is slower than the vaporizing rates of hydrogen peroxide and ammonium hydroxide with the room temperature in the conventional technology without temperature control. In a preferred embodiment, the temperatures of hydrogen peroxide and ammonium hydroxide is among 12 degree centigrade to 18 degree centigrade.
Thereafter, hydrogen peroxide, ammonium hydroxide and water with said temperature are mixed to form an etchant in step 2, and the temperature of the etchant is maintained below the room temperature and above 12 degree centigrade. In a preferred embodiment, water used in the etching process 100 could be deionized water, wherein the weight ratio of (hydrogen peroxide: ammonium hydroxide: water) of the etchant is (3:8:9), for example.
Comparing to the conventional etching process, the temperature of the etchant in the etching process 100 is maintained below the room temperature and above 12 degree, such that vaporizing rates of hydrogen peroxide and ammonium hydroxide in the etchant are slow. Therefore, the variation of the concentration of the etchant caused by the vaporization of the components of the etchant in the conventional etching process will no occur in the etchant in the etching process 100, and the etchant in the etching process 100 according to the present invention has more stable concentration consequently.
Afterward, the etchant is used for etching the copper film or the silver film in step S3. With the etchant having stable concentration, the etching rates for the copper film or the silver film in the etching process 100 are more stable than that in the conventional etching process. The detail etching process and the corresponding etching apparatus will be described with referring to the following preferred embodiment.
FIG. 2 is a schematic view of an etching apparatus according to one embodiment of the present invention. Referring to FIG. 2, an etching apparatus 200 includes a hydrogen peroxide tank 210, an ammonium hydroxide tank 220, a water tank 230, an etching tank 240, a piping system 250 and a temperature control device 260. In a preferred embodiment, water inside the water tank 230 can be the deionized water. The hydrogen peroxide tank 210, the ammonium hydroxide tank 220 and the water tank 230 are connected to the etching tank 250 with the piping system 250, wherein a valve 252 can be connected to the piping system 250 optionally as need for adjusting the flow of hydrogen peroxide, ammonium hydroxide or water. The temperature control device 260 could be the heat exchanger such as the refrigerating pipe or similar, and the temperature control device 260 is disposed around the hydrogen peroxide tank 210, the ammonium hydroxide tank 220 and the etching tank 240 for maintaining the temperature below the room temperature and above 12 degree centigrade. Wherein, if the room temperature is 22 degree centigrade (or 23 degree centigrade), the temperatures of the tanks 210, 222, 240 are controlled between 12 degree centigrade to 22 degree centigrade (or 12 degree centigrade to 23 degree centigrade). In a preferred embodiment, the temperatures controlled by the temperature control device 260 is prefer to be restricted within 12 degree centigrade to 18 degree centigrade for the etching apparatus 200 with the more stable etching rate.
Hydrogen peroxide, ammonium hydroxide and water are delivered through the piping system 250 from the hydrogen peroxide tank 210, the ammonium hydroxide tank 220 and the water tank 230 to the etching tank 240, respectively. Since the temperatures of hydrogen peroxide tank 210 and ammonium hydroxide tank 220 are maintained below the room temperature and above 12 degree centigrade by the temperature control device 260, the bubbles formed from the vaporized hydrogen peroxide and ammonium hydroxide during delivering in the etching apparatus 200 can be decreased with comparing to the conventional etching apparatus, and the piping system 250 will not be blocked by the bubbles. Moreover, the etching apparatus of this embodiment further includes flow meter 270 disposed between the hydrogen peroxide tank 210, the ammonium hydroxide tank 220, the water tank 230 and the etching tank 240 for controlling the flow of hydrogen peroxide, ammonium hydroxide and water in the piping system 250.
In a preferred embodiment, the piping system 250 can be optionally connected to the pump 254 as need for providing sufficient driving force in the etching apparatus 200, such that hydrogen peroxide, ammonium hydroxide and water can be successfully delivered to the etching tank 240. It should be noted that the using of the pump 254 is not necessary in the present invention. Any other components capable of driving the etching apparatus 200 by gravity or other pressurizing method could be disposed in this system. Otherwise, in another preferred embodiment, the temperature control device 260 can be further disposed around the water tank 230 to maintain the temperature of the water tank 230 below the room temperature and above 12 degree centigrade.
Hydrogen peroxide, ammonium hydroxide and water are mixed in the etching tank 240 for forming the etchant, and temperature of the etching tank 240 is maintained below the room temperature and above 12 degree centigrade by the temperature control device 260. Therefore, the vaporizing rates of hydrogen peroxide and ammonium hydroxide in the etching apparatus 200 are slower than that in the conventional etching apparatus, such that the concentration of the etchant would no be changed with the vaporization of hydrogen peroxide and ammonium hydroxide. Thereafter, the copper film or the silver film is etched with this etchant. With fewer variation of the concentration of the etchant in the etching apparatus 200, the etching rate of the etching apparatus 200 will be more stable than that of the conventional etching apparatus.
FIG. 3 is a schematic view of an etching apparatus according to another one embodiment of the present invention. Referring to FIG. 3, the etching apparatus 200′ is similar to the etching apparatus 200 shown in FIG. 2, the same elements in the etching apparatus 200′ are designated by the same reference numerals as those of the etching apparatus 200. The difference between the etching apparatus 200′ shown in FIG. 3 and the etching apparatus 200 shown in FIG. 2 is that a buffer tank 280 is disposed between the hydrogen peroxide tank 210, the ammonium hydroxide tank 220, the water tank 230 and the etching tank 240 of the etching apparatus 200′. Wherein, the hydrogen peroxide tank 210, the ammonium hydroxide tank 220 and the water tank 230 are connected to the buffer tank 280 through the piping system 250, and the buffer tank 280 is also connected to the etching tank 240 through the piping system 250. Consequently, hydrogen peroxide, ammonium hydroxide and water will be channelled to the buffer tank 280 and the etching tank 240 sequentially. In detail, the buffer tank 280 is used to pre-mix hydrogen peroxide, ammonium hydroxide and water or buffer for the etching tank 240. Moreover, the buffer tank 280 can be used to measure the weights of hydrogen peroxide, ammonium hydroxide and water, so as to provided hydrogen peroxide, ammonium hydroxide and water with fixed weight ratio into etching tank 240.
Referring to FIG. 3, in a preferred embodiment, the temperature control device 260 may further disposed around the piping system 250 for maintaining the temperatures of hydrogen peroxide, ammonium hydroxide and water during delivering, such that the temperatures of hydrogen peroxide, ammonium hydroxide and water the will not be affected by the environment during delivering. In another preferred embodiment, the temperature control device 260 can be further disposed around the water tank 230 for maintaining the temperatures of the water tank 230 below the room temperature and above 12 degree centigrade. Hence, the temperatures of hydrogen peroxide, ammonium hydroxide and water will be changed slowly during mixing. It should be note that the using of the pump 254, the flow meter 270 and the buffer tank 280 and the location of the temperature control device 260 in the described two embodiments are not restrictions for the present invention. The using of said device and the location of the temperature control device 260 in the present invention should be designed to meet the practical requirements.
In summary, with the using of the temperature control device in the etching apparatus of the present invention, the temperatures of hydrogen peroxide and ammonium hydroxide in the etching process are maintained below the room temperature and above 12 degree centigrade. Hence, the piping system will not be blocked by the bubbles, and the decrease of flow or the block caused by the bubbles can be eliminated from the piping system. The vaporizing rates of hydrogen peroxide and ammonium hydroxide in the present invention are lower than that in the conventional technology, and the etchant with stable concentration can etch the copper film or the silver film in steady etching rate. Moreover, the vaporization of ammonium hydroxide in the present invention can be decreased, and the stimulative smell produced by vaporized ammonium hydroxide could be decreased consequently.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. An etching apparatus for etching copper or silver, comprising:

a hydrogen peroxide tank;

an ammonium hydroxide tank;

a water tank;

an etching tank;

a piping system, configured to make the hydrogen peroxide tank, the ammonium hydroxide tank and the water tank to be connected with the etching tank; and

a temperature control device, disposed around the hydrogen peroxide tank, the ammonium hydroxide tank and the etching tank to maintain the temperatures of them below the room temperature and above 12 degree centigrade.

2. The etching apparatus according to claim 1, wherein the temperatures of the hydrogen peroxide tank, the ammonium hydroxide tank and the etching tank are maintained among 12 degree centigrade to 18 degree centigrade.

3. The etching apparatus according to claim 1, wherein the temperature control device is also disposed around the water tank to maintain the temperature of the water tank below the room temperature and above 12 degree centigrade.

4. The etching apparatus according to claim 1, wherein the temperature control device is also disposed around the piping system to maintain the temperature of the piping system below the room temperature and above 12 degree centigrade.

5. The etching apparatus according to claim 1, further comprising a buffer tank disposed between the hydrogen peroxide tank, the ammonium hydroxide tank, the water tank and the etching tank, and the hydrogen peroxide tank, the ammonium hydroxide tank and the water tank are connected to the buffer tank through the piping system, and the buffer tank is also connected to the etching tank through the piping system.

6. The etching apparatus according to claim 5, wherein the temperature control device is also disposed around the buffer tank to maintain the temperature of the buffer tank below the room temperature and above 12 degree centigrade.

7. The etching apparatus according to claim 1, further comprising a pump connected to the piping system.

8. The etching apparatus according to claim 1, further comprising a flow meter disposed in the piping system between the hydrogen peroxide tank, the ammonium hydroxide tank, the water tank and the etching tank.