METHOD OF ETCHING A MULTI-LAYER
A method of etching a multi-layer is provided. The multi-layer includes an aluminum layer disposed on a semiconductor substrate and an anti-reflection coating layer disposed on the aluminum layer. The method includes: performing a first etching process to etch the anti-reflection coating layer by providing a first etching gas, wherein the first etching gas includes a chlorine-containing substance; then performing a second etching process to etch the aluminum layer by providing a second etching gas, wherein the second etching gas does not include a chlorine-containing compound.
1. Field of the Invention
The present invention relates to a method of etching a multi-layer, especially to a method that can prevent excess polymer residue on the sidewall and the corrosion of the aluminum layer.
2. Description of the Prior Art
In modern society, the micro-processor system comprised of integrated circuits (IC) is a ubiquitous device, being utilized in such diverse fields as automatic control electronics, mobile communication devices and personal computers.
To connect various active or passive components on the semiconductor substrate, metal aluminum or its alloy is usually used as a conducting wire. By some patterning processes, a complex interconnection system is gradually formed. A conventional method of forming a patterned aluminum layer is to deposit a photoresist layer on the aluminum layer, and then performing a photo-etching-process (PEP) with a patterned photo mask, then transferring the pattern of the photoresist layer onto the aluminum layer.
Please refer to
Due to the different materials of each layer in the multi-layer, it is necessary to use different etching gas recipes to accurately remove the ARC layer 16 and the aluminum layer 14. The etching gas recipes usually include chlorine gas, BCl3 N2, CHF3 or hydrocarbon. The chlorine gas and BCl3 are used as the etching gas to anisotropically etch the ARC layer 16 and the aluminum layer 14 when they are transferred to radical by the plasma in the etching chamber. In order to maintain the good directionality, a passivation gas is used to produce polymer on the sidewall to obtain a good sidewall protection.
It is known that BCl3 can not only function as an etching gas but also has passivation effect. It has therefore been widely used in various anisotropic etching processes. However, using BCl3 may also bring some shortcomings such as excess loose polymer residue formed on the sidewall and thus the corrosion of the aluminum layer or other shortcomings. As shown in
As a result, a simple etching process to etch the aluminum layer and the ARC layer that can prevent excess polymer residue production and corrosion of aluminum layer is still needed.
SUMMARY OF THE INVENTIONThe present invention provides a method of etching a multi-layer, especially a method that can reduce the phenomenon of excess polymer residue and can produce more compact polymer residue so as to prevent the corrosion of aluminum layer in the multi-layer.
According to the present invention, a method of etching a multi-layer is provided. The multi-layer comprises an aluminum layer disposed on a semiconductor substrate and an anti-reflection coating layer disposed on the aluminum layer. The method comprises: performing a first etching process to etch the anti-reflection coating layer by providing a first etching gas, wherein the first etching gas comprises a chlorine-containing substance; then performing a second etching process to etch the aluminum layer by providing a second etching gas, wherein the second etching gas does not comprise a chlorine-containing compound.
According to the present invention, a method of anisotropically etching an aluminum layer is provided. The method comprises: providing an etching gas to etch the aluminum layer, wherein the etching gas comprises a chlorine-containing substance, but does not comprise a chlorine-containing compound.
The method of etching a multi-layer in the present invention excludes chlorine-containing compound as an etching gas, not only providing a more simple process but also reducing the phenomenon of excess polymer residue and corrosion of aluminum layer, and leading to a better etching result.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Please refer to
Step 100: providing a multi-layer disposed on a semiconductor substrate, wherein the multi-layer comprises at least an aluminum layer and an anti-reflection coating (ARC) layer disposed on the aluminum layer.
Step 102: utilizing a patterned mask to perform a first etching process to etch the ARC layer by providing a first etching gas and a first passivation gas, wherein the first etching gas comprises a chlorine-containing substance.
Step 104: after step 102, performing a second etching process to etch the aluminum layer by providing a second etching gas and a second passivation gas, wherein the second etching gas does not comprise a chlorine-containing compound.
Step 106: after etching the aluminum layer, performing an over etching process to etch a barrier layer disposed under the aluminum layer.
For more detailed descriptions of each step, please refer to
Please refer to
The first etching process is carried out in a plasma etching chamber. Table 1 provides a preferred etching recipe and operation condition when the first etching gas 126 is chlorine gas. As shown in Table 1, the first etching process is performed under a condition as follows: a pressure between 12 and 18 mTorr, a RF power between 1200 and 1600 W, a bias power between 250 W and 350 W, a period between 120 and 180 seconds, a flow rate of chlorine gas between 150 and 210 sccm (standard cubic centimeter per minute) and a flow rate of ethylene between 120 and 180 sccm. The reaction time of the first etching process may be adjusted depending on the material or thickness of the ARC layer 116. It can be longer or short and is not limited to Table 1.
Please refer to
When finishing step 102 and step 104, the pattern of the mask layer 122 has been transferred to the aluminum layer 114, forming a patterned aluminum layer 114. Referring to
As described above, BCl3 is usually used as an etching and a passivation gas in conventional arts, which may results in excess polymer residue formed on the sidewall of the patterned aluminum layer and thus brings to the serious etching and even corrosion of the aluminum layer. The present invention therefore provides an etching method that avoids using chlorine-containing compound such as BCl3 as an etching gas, and in combination with a passivation gas such as hydrocarbon. In conventional arts, BCl3 produces sidewall polymer by bombarding the mask layer, but the formed sidewall polymer is usually not compact. In contrast, hydrocarbon has longer polymer chains and thus more condensed structure ([C—H]x), it can completely replace the passivation function of BCl3. The sidewall protection is not reduced with the removal of BCl3. On the contrary, removing BCl3 can avoid corrosion of the aluminum layer caused by too much Clplasma trapped in the polymer residue. As a result, the method of etching a multi-layer in the present invention not only provides a simpler process by removing chlorine-containing compound as an etching gas, but also can reduce the phenomenon of excess polymer residue and corrosion of aluminum layer, leading to a better etching result.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.
Claims
1. A method of etching a multi-layer, the multi-layer comprising an aluminum layer disposed on a semiconductor substrate and an anti-reflection coating (ARC) layer disposed on the aluminum layer, the method comprising:
- performing a first etching process to etch the ARC layer by providing a first etching gas, wherein the first etching gas comprises a chlorine-containing substance; and
- performing a second etching process to etch the aluminum layer by providing a second etching gas, wherein the second etching gas does not comprise a chlorine-containing compound.
2. The method as in claim 1, wherein the chlorine-containing compound comprises BCl3.
3. The method as in claim 1, wherein the second etching gas comprises chlorine gas.
4. The method as in claim 1, wherein the first etching gas comprises chlorine gas and BCl3.
5. The method as in claim 1, wherein the first etching gas comprises chlorine gas.
6. The method as in claim 1, wherein the first etching process further comprises providing a first passivation gas.
7. The method as in claim 6, wherein the first passivation gas comprises hydrocarbon.
8. The method as in claim 6, wherein the first passivation gas comprises ethylene (C2H4).
9. The method as in claim 1, wherein the second etching process further comprises providing a second passivation gas.
10. The method as in claim 9, wherein the second passivation gas comprises hydrocarbon.
11. The method as in claim 9, wherein the second passivation gas comprises ethylene.
12. The method as in claim 6, wherein the first etching process is performed under a condition as follows: a pressure between 12 and 18 mTorr, a RF power between 1200 and 1600 W, a bias power between 250 W and 350 W, a period between 120 and 180 seconds, a flow rate of the first etching gas between 150 and 210 sccm and a flow rate of the first passivation gas between 120 and 180 sccm.
13. The method as in claim 9, wherein the second etching process is performed under a condition as follows: a pressure between 8 and 12 mTorr, a RF power between 1300 and 1700 W, a bias power between 250 W and 350 W, a flow rate of the second etching gas between 120 and 180 sccm and a flow rate of the second passivation gas between 120 and 180 sccm.
14. A method of anisotropically etching an aluminum layer, comprising: providing an etching gas to etch the aluminum layer, wherein the etching gas comprises a chlorine-containing substance, but does not comprise a chlorine-containing compound.
15. The method as in claim 14, wherein the chlorine-containing compound comprises BCl3.
16. The method as in claim 14, wherein the etching gas comprises chlorine gas.
17. The method as in claim 14, further comprising providing a passivation gas.
18. The method as in claim 17, wherein the passivation gas comprises hydrocarbon.
19. The method as in claim 17, wherein the passivation gas comprises ethylene.
20. The method as in claim 17, wherein the etching process is performed under a condition as follows: a pressure between 8 and 12 mTorr, a RF power between 1300 and 1700 W, a bias power between 250 W and 350 W, a flow rate of the etching gas between 120 and 180 sccm and a flow rate of the passivation gas between 120 and 180 sccm.
Type: Application
Filed: Jun 26, 2009
Publication Date: Dec 30, 2010
Inventors: Zhen Yu Zhuo (Singpore), Shi Jie Bai (Singpore)
Application Number: 12/492,152
International Classification: C23F 1/02 (20060101);