Cleaning method of etching chamber

Abstract

The present invention provides a cleaning method for an etching chamber, provides an etching machine and a wafer group including multiple wafers, selects N wafers therefrom, each of which has a metal interconnection structure formed thereon, and the etching chamber in the etching machine includes an electrostatic chuck having multiple air holes; sequentially fixing the first to N-1th wafers to the electrostatic chuck for etching, and in the time period between etching of the two wafers, introducing a first cleaning gas into the etching chamber, utilizing the first cleaning gas ionization to form a first plasma cleaning etching chamber; moving the Nth wafer to the electrostatic chuck for etching, and then introducing a first cleaning gas into the etching chamber, utilizing the first cleaning gas ionization to form a first plasma cleaning etching chamber. The present invention removes the gas that damages the electrostatic chuck during wafer-free automatic dry etching cleaning, adds a cleaning method for covering the wafer, effectively cleaning the etching byproducts in the etching chamber while protecting the electrostatic chuck.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a cleaning method for an etching chamber. Background Art

[0002] In the 12-inch plasma etching process, such as etching a tungsten layer, to prevent byproducts such as tungsten polymers from being produced in the etching chamber, a WAC (Wafer-less Auto Clean) containing SF6 / O2 is generally used to self-clean the etching chamber between wafers to effectively prevent the byproducts from falling during the etching process, thereby preventing the accumulated byproducts from contaminating the substrate surface and adversely affecting the process results.

[0003] However, when the waferless automatic dry etching cleans the self-cleaning etching chamber between wafers, the surface of the ESC (electrostatic chuck) in the etching chamber is completely exposed, and the SF6 in the waferless automatic dry etching cleaning will inevitably damage the surface of the electrostatic chuck; as the RF source hours increase, the waferless automatic dry etching cleaning containing SF6 will cause more and more serious damage to the electrostatic chuck surface and He pores, eventually leading to the machine B / he alarm, or even breakage, seriously affecting the etching chamber operation time and production volume.

[0004] In order to solve the above problems, a new cleaning method for the etching chamber needs to be proposed. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a cleaning method for an etching chamber, which is used to solve the problem in the prior art that when the waferless automatic dry etching cleaning self-cleaning etching chamber between wafers, the surface of the electrostatic chuck in the etching chamber is completely exposed, and the etching gas in the waferless automatic dry etching cleaning, such as SF6, will inevitably damage the surface of the electrostatic chuck; as the number of RF source hours increases, the waferless automatic dry etching cleaning containing SF6 will cause more and more serious damage to the electrostatic chuck surface and He pores, eventually leading to machine B / he alarms and even fragmentation, seriously affecting the operating time and production volume of the etching chamber.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a method for cleaning an etching chamber, comprising:

[0007] Step 1: Provide an etching machine and a wafer group including multiple wafers, select N wafers from the wafers, each of which has a metal interconnect structure formed thereon, and an etching chamber in the etching machine includes an electrostatic chuck having multiple air holes;

[0008] Step 2: sequentially fix the first to N-1th wafers on the electrostatic chuck for etching, and in the time period between etching two wafers, introduce a first cleaning gas into the etching chamber, and use the first plasma formed by ionization of the first cleaning gas to clean the etching chamber; wherein,

[0009] The etching degree of the electrostatic chuck by the first plasma is less than a preset value, and the first plasma is used to remove a portion of byproducts of the metal interconnect structure;

[0010] Step 3: Move the Nth wafer to the electrostatic chuck for etching, then introduce a first cleaning gas into the etching chamber, and use the first plasma formed by ionization of the first cleaning gas to clean the etching chamber; then introduce a second cleaning gas into the etching chamber, adjust the etching chamber to a first pressure, and use the second plasma formed by ionization of the second cleaning gas to clean the electrostatic chuck and the area above the etching chamber; adjust the etching chamber to a second pressure, and use the second plasma to clean the area below the electrostatic chuck in the etching chamber; wherein,

[0011] The etching degree of the electrostatic chuck by the second plasma is greater than the preset value, and the second plasma is used to remove byproducts of another part of the metal interconnect structure.

[0012] Preferably, the wafer in step 1 is a silicon wafer.

[0013] Preferably, the material of the metal interconnect structure in step 1 includes titanium and tungsten.

[0014] Preferably, the material of the electrostatic chuck in step 1 is alumina.

[0015] Preferably, the air holes in step 1 are used to introduce helium gas and boron gas into the etching chamber.

[0016] Preferably, the first cleaning gas in steps 2 and 3 is chlorine.

[0017] Preferably, the second cleaning gas in step three is a mixed gas of SF6 and O2.

[0018] Preferably, in step three, the first pressure is not less than 20 mTorr, the volume ratio of the SF6 to the O2 is 5:1, and the total gas flow rate does not exceed 250 sccm.

[0019] Preferably, in step three, the second pressure is not higher than 10 mTorr, the volume ratio of the SF6 to the O2 is 5:1, and the total gas flow rate does not exceed 250 sccm.

[0020] Preferably, after cleaning the etching chamber in steps 2 and 3, the process further includes introducing oxygen into the etching chamber to remove the first cleaning gas or the second cleaning gas.

[0021] As described above, the cleaning method of the etching chamber of the present invention has the following beneficial effects:

[0022] The present invention eliminates the gas that damages the electrostatic chuck during wafer-free automatic dry etching cleaning, adds a cleaning method that covers the wafer, effectively cleans etching byproducts in the etching chamber, and protects the electrostatic chuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic diagram of the electrostatic chuck structure of the prior art;

[0024] Figure 2 Shown is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention.

[0026] See also Figure 2 The present invention provides a method for cleaning an etching chamber, comprising:

[0027] Step 1: Provide an etching machine and a wafer group including multiple wafers, select N wafers from the wafers, each of which has a metal interconnect structure formed thereon, and an etching chamber in the etching machine includes an electrostatic chuck having multiple air holes;

[0028] In an embodiment of the present invention, the wafer in step 1 is a silicon wafer.

[0029] In an embodiment of the present invention, the material of the metal interconnect structure in step 1 includes titanium and tungsten. For example, when forming a contact hole structure, titanium and tungsten are required to fill the contact hole. When etching the metal, by-products will be formed and attached to the etching cavity.

[0030] In an embodiment of the present invention, the material of the electrostatic chuck in step 1 is alumina. Figure 1 When the etching gas includes SF6, the damage mechanism of the electrostatic chuck is as follows:

[0031] SF6+O2→SO2F2+F*;

[0032] SO2F2+Al2O3→AlF3+SO2.

[0033] In an embodiment of the present invention, the gas holes in step 1 are used to introduce helium gas and boron gas into the etching chamber.

[0034] Step 2: sequentially fix the first to N-1th wafers on the electrostatic chuck for etching. In the time period between etching two wafers, that is, the time when there is no wafer in the etching chamber, a first cleaning gas is introduced into the etching chamber, and the etching chamber is cleaned by using a first plasma formed by ionization of the first cleaning gas; wherein,

[0035] The first plasma etches the electrostatic chuck to a lesser extent than a preset value, and is used to remove byproducts of some metal interconnect structures; that is, compared to the prior art, the plasma that is likely to damage the surface of the electrostatic chuck is removed during the inter-wafer self-cleaning step.

[0036] In an embodiment of the present invention, the first cleaning gas in step 2 is chlorine gas, which is used to remove byproducts of titanium etching in the etching chamber.

[0037] In an embodiment of the present invention, after the cleaning of the etching chamber is completed in step 2, the step further includes introducing oxygen into the etching chamber to remove the first cleaning gas.

[0038] Step 3: Move the Nth electrostatic chuck to the electrostatic chuck for etching, then introduce the first cleaning gas into the etching chamber, and use the first cleaning gas to ionize to form a first plasma to clean the etching chamber; then introduce the second cleaning gas into the etching chamber, adjust the etching chamber to a first pressure, and use the second plasma formed by the ionization of the second cleaning gas to clean the electrostatic chuck and the area above the etching chamber; adjust the etching chamber to a second pressure, and use the second plasma to clean the area below the electrostatic chuck in the etching chamber; wherein,

[0039] The second plasma etches the electrostatic chuck to a greater extent than a preset value and is used to remove byproducts from another portion of the metal interconnect structure. This eliminates the gases that damage the electrostatic chuck during waferless automated dry etching, adds a cleaning method that covers the wafer, and effectively removes etching byproducts from the etch chamber while protecting the electrostatic chuck.

[0040] For example, if a lot of 12 wafers is used, 12 wafers (i.e., the entire lot) can be selected and the first through eleventh wafers can be sequentially mounted on an electrostatic chuck for etching. In the interval between etching of two wafers (i.e., when no wafers are in the etching chamber), a first cleaning gas is introduced into the etching chamber, and the first cleaning gas is ionized to form a first plasma to clean the etching chamber. The twelfth wafer is then moved to the electrostatic chuck for cover wafer cleaning. It should be noted that the cover wafer cleaning step can also be performed after other wafers in a lot are mounted on the electrostatic chuck.

[0041] In an embodiment of the present invention, the first cleaning gas in step three is chlorine gas.

[0042] In an embodiment of the present invention, the second cleaning gas in step three is a mixed gas of SF6 and O2.

[0043] In an embodiment of the present invention, the first pressure in step three is not less than 20 mTorr, the volume ratio of SF6 to O2 is 5:1, and the total gas flow rate does not exceed 250 sccm. Under normal circumstances, the RF source in the etching chamber is at the top, that is, the area above the electrostatic chuck in the etching chamber has more by-products. The use of high-pressure SF6 and O2 gases can enhance the cleaning effect.

[0044] In an embodiment of the present invention, the second pressure in step three is no higher than 10 mTorr, the volume ratio of SF6 to O2 is 5:1, and the total gas flow rate does not exceed 250 sccm. Normally, the RF source in the etching chamber is at the top, which means that the area below the electrostatic chuck in the etching chamber has fewer by-products. The use of low-pressure SF6 and O2 gases can ensure the cleaning effect while extending the service life of the electrostatic chuck.

[0045] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0046] In summary, the present invention eliminates gases that damage the electrostatic chuck during waferless automated dry etching, adds a cleaning method that covers the wafer, and effectively removes etching byproducts from the etching chamber while protecting the electrostatic chuck. Therefore, the present invention effectively overcomes the shortcomings of the prior art and has high industrial application value.

[0047] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for cleaning an etching chamber, characterized in that: At least: Step 1: Provide an etching machine and a wafer group including multiple wafers, select N wafers from the wafers, each of which has a metal interconnect structure formed thereon, and an etching chamber in the etching machine includes an electrostatic chuck having multiple air holes; Step 2: sequentially fix the first to N-1th wafers on the electrostatic chuck for etching, and in the time period between etching two wafers, introduce a first cleaning gas into the etching chamber, and use the first cleaning gas to ionize and form a first plasma to clean the etching chamber; wherein, The etching degree of the electrostatic chuck by the first plasma is less than a preset value, and the first plasma is used to remove a portion of byproducts of the metal interconnect structure; Step 3: Move the Nth wafer to the electrostatic chuck for etching, then introduce a first cleaning gas into the etching chamber, and use the first cleaning gas to ionize to form a first plasma to clean the etching chamber; then introduce a second cleaning gas into the etching chamber, wherein the second cleaning gas is a mixture of SF6 and O2, and the etching chamber is adjusted to a first pressure, and the electrostatic chuck and the area above the electrostatic chuck in the etching chamber are cleaned by using a second plasma formed by ionization of the second cleaning gas, wherein the first pressure is not less than 20 mTorr, the volume ratio of SF6 to O2 is 5:1, and the total gas flow rate does not exceed 250 sccm; adjust the etching chamber to a second pressure, and use the second plasma to clean the area below the electrostatic chuck in the etching chamber, wherein the second pressure is not higher than 10 mTorr, the volume ratio of SF6 to O2 is 5:1, and the total gas flow rate does not exceed 250 sccm; The etching degree of the electrostatic chuck by the second plasma is greater than the preset value, and the second plasma is used to remove byproducts of another part of the metal interconnect structure.

2. The method for cleaning an etching chamber according to claim 1, wherein: The wafer in step 1 is a silicon wafer.

3. The method for cleaning an etching chamber according to claim 1, wherein: The material of the metal interconnect structure in step 1 includes titanium and tungsten.

4. The method for cleaning an etching chamber according to claim 1, wherein: The material of the electrostatic chuck in step 1 is alumina.

5. The method for cleaning an etching chamber according to claim 1, wherein: The air holes in step 1 are used to introduce helium gas and boron gas into the etching chamber.

6. The method for cleaning an etching chamber according to claim 3, wherein: The first cleaning gas in steps 2 and 3 is chlorine.

7. The method for cleaning an etching chamber according to claim 1, wherein: After the etching chamber is cleaned in steps 2 and 3, the process further includes introducing oxygen into the etching chamber to remove the first cleaning gas or the second cleaning gas.

Images