• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    PURPOSE: A method for etching a metal layer of a semiconductor device is provided to prevent a damage of a lower insulating layer by increasing an etch selectivity between an aluminium layer and a diffusion barrier. CONSTITUTION: A method for etching a metal layer of a semiconductor device is to form a metal wiring by etching a diffusion barrier, an aluminium layer, and a reflection barrier accumulated on an insulating layer. The method comprises the steps of: etching the aluminium layer and the reflection barrier after setting a bout 80% of the aluminium layer as an etch ending point; increasing an etch selectivity of the aluminium layer and the diffusion barrier and etching the remaining aluminium etch layer; and etching the diffusion barrier until the insulating layer is exposed.
    公开号:KR20000042670A
    申请号:KR1019980058921
    申请日:1998-12-26
    公开日:2000-07-15
    发明作者:백계현；신강섭
    申请人:김영환；현대전자산업 주식회사；
    IPC主号:
    专利说明:

    Metal film etching method of semiconductor device
    The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a metal film etching method for preventing damage to a lower insulating film by increasing the etching selectivity between aluminum film (Al) and diffusion barrier film (TiN) during metal wiring. will be.
    1A and 1B are cross-sectional views illustrating a method for forming metal wirings according to the prior art, which will be described below.
    First, as shown in FIG. 1A, an insulating film 2 is deposited on a silicon substrate 1 on which predetermined patterns are formed, and contact holes are formed in the insulating film 2 by a photolithography process. Then, in order to prevent the metal atoms from being diffused into the insulating film or the silicon substrate, a titanium nitride film (TiN) diffusion barrier 3 is deposited on the whole, and widely used as a material for the metal wiring on the diffusion barrier 3. After the deposition of the aluminum film 4, the titanium film / titanium nitride film (Ti / TiN) material to facilitate the etching on the aluminum film in the subsequent dry etching process on the aluminum film (4) The anti-reflection film 5 is deposited.
    Then, as shown in FIG. 1B, the anti-reflection film 5, the aluminum film 4, and the diffusion barrier 3 are simultaneously etched through a dry etching process to form the metal wiring 10.
    In the above, a plasma etching process is usually used as an etching process for forming metal wiring. The principle of the plasma etching process is as follows.
    First, the etching gas is discharged to generate plasma ions, so that the plasma ions are diffused and adsorbed onto the metal film to be etched. Accordingly, the plasma ions adsorbed on the surface of the metal film diffuse into it and react with the metal atoms, and as a result, by-products are generated and these by-products are desorbed from the metal film. Subsequently, when the by-products are removed, the plasma etching process for the metal film is completed to form metal wires in a desired pattern in place.
    On the other hand, in order to improve the characteristics of the plasma etching process performed by the above-mentioned principle, recently, the pressure of the etching gas is lowered, and the plasma density is increased, thereby increasing the etching rate and facilitating control of the process.
    However, in a typical plasma etching process, the etching speed is unevenly generated for each region according to the difference in density of the patterns. This phenomenon is referred to as a loading effect, which is because the region where the pattern is dense in the etching process has more interference with the etching process than other regions.
    FIG. 2 illustrates light emission signals of aluminum when plasma etching is performed under a process condition of 450 W of source power, 130 W of bottom power, 30 sccm of BCl 3 gas, 60 sccm of Cl 2 gas, and 9 mTorr of Cl 2 gas. It is a figure which shows.
    In the drawing, time periods 0 to 8 seconds are sections in which a titanium / titanium nitride film (Ti / TiN), which is an antireflection film, is removed. The instantaneous increase in the light emission signal in the time band 8 to 9 seconds is indicated by the etching of the aluminum film in the region where the etching speed is relatively high. The light emission signal in the time band of 9 to 35 seconds is shown while the aluminum film is continuously etched. The decrease in the light emission signal in the time band 35 to 38 seconds is indicated by the removal of the aluminum film in the region where the etching speed is high.
    FIG. 3 is a photograph showing an etch profile of an actual pattern for a light emission signal appearing from 0 to 38 seconds in the time band of FIG. 2, in which an aluminum film of an area having a dense pattern is roughly compared to an area having a dense pattern. It can be seen that about 20% less etching.
    Subsequently, the period of 38 to 42 seconds in the time band shown in FIG. 2 is a light emission signal which is displayed while the aluminum film is etched in a region having a dense pattern. At this time, in the region where the etching speed is relatively high, etching of the diffusion barrier layer TiN, which is a lower layer of the aluminum layer, occurs.
    On the other hand, in order to eliminate the etching rate non-uniformity of the aluminum film caused by the loading effect phenomenon, conventionally, a sufficient excess etching process is performed, 42 seconds after the time band of FIG.
    However, when the excessive etching process is performed in order to reduce the loading effect phenomenon, the step between the aluminum film in the dense area and the other areas does not occur because the aluminum film in the area where the pattern is dense is removed. However, as shown in FIG. 4, since etching of the lower insulating film occurs in a region where the pattern is not dense, a step between the lower insulating films occurs. However, the loss of the lower insulating film and the generation of the step are difficult to set a target during the deposition and planarization process of another insulating film performed after the etching process, and also adversely affects the uniformity.
    In addition, in order to compensate for the step difference of the lower insulating film, since the deposition thickness of the insulating film deposited subsequently is increased, the amount to be flattened by that much increases, which is not preferable in terms of productivity.
    In addition, during the excessive etching process, the via power is strongly applied in order to improve the directionality of the ions. At this time, the damage caused by the plasma occurs, which adversely affects the characteristics of the device.
    Accordingly, the present invention devised to solve the above problems, by increasing the etch selectivity between the aluminum film and the diffusion barrier film of the titanium nitride film, the lower insulating film in the region where the pattern is dense and other regions during the transient etching process SUMMARY OF THE INVENTION An object of the present invention is to provide a method for etching a metal film of a semiconductor device capable of preventing a step difference from occurring.
    1A and 1B are cross-sectional views illustrating a method of forming metal wirings according to the prior art.
    2 is a view showing a light emission signal of aluminum that appears during the plasma etching process.
    3 is a photograph showing a state in which a loading effect phenomenon occurs.
    Figure 4 is a photograph showing a pattern profile in the case of performing the excessive etching.
    5A to 5D are graphs showing etching selectivity ratios between aluminum films and diffusion barrier films according to process variables.
    The metal film etching method of the semiconductor device of the present invention for achieving the above object is a method for forming a metal wiring by etching the diffusion barrier film, the aluminum film and the anti-reflection film stacked on the insulating film, 80% of the aluminum film The first step etching process for etching the anti-reflection film and the aluminum film with the degree of etching as the end point, the second step etching process for etching the remaining aluminum film by increasing the etch selectivity of the aluminum film and the diffusion barrier film, and the insulating film And a third step etching process of etching the diffusion barrier layer until it is exposed.
    According to the present invention, by improving the etching selectivity between the aluminum film and the diffusion barrier film of the titanium nitride film, it is possible to prevent the step difference between the lower insulating film in the region where the pattern is dense and the region where the pattern is not.
    Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
    As described above, during the conventional etching process, the diffusion barrier film of the non-dense pattern area is exposed in the time band from 35 to 42 seconds in FIG. 2, while the aluminum film of the area having the dense pattern is exposed. If the over-etching process is performed in this state, damage to the lower insulating film occurs in an area where the pattern is not dense.
    Therefore, the basic principle of the present invention is to perform the etching process under the condition that the etching selectivity between the diffusion barrier film and the aluminum film is increased in the time band (35 to 42 seconds), the metal film in the region with a dense pattern and other regions By preventing the step difference from occurring, the etching of the lower insulating film is prevented from occurring in the region where the pattern is not dense during the subsequent etching process.
    In other words, while the etching speed of the aluminum film is increased in the time band of 35 to 42 seconds, the etching rate of the diffusion barrier film made of titanium nitride is relatively slow, thereby delaying the etching of the diffusion barrier film in a region where the pattern is not dense. The aluminum film in the dense area is removed to expose the diffusion barrier, which is the lower layer, and as a result, the step difference between the two areas due to the difference in pattern density is prevented.
    In addition, the subsequent over-etching process is performed by an ion sputter process in which a loading effect phenomenon is relatively low, thereby preventing etching of the lower insulating film to the maximum.
    In the embodiment of the present invention, in order to obtain the results as described above, the etching selectivity ratio between the aluminum film and the diffusion barrier according to the process variable was considered, and based on this, the optimum process conditions were set.
    5A to 5D are graphs showing an etching selectivity ratio between an aluminum film and a titanium nitride film according to process variables, and FIG. 5A illustrates an etching selectivity ratio between an aluminum film and a titanium nitride film according to source power. 5b shows the etching selectivity between the aluminum film and the titanium nitride film according to the bottom power, Figure 5c shows the etching selectivity between the aluminum film and titanium nitride film according to the mixing ratio of the etching gas BCl 3 and Cl 2 . 5D shows the etching selectivity between the aluminum film and the titanium nitride film according to the pressure.
    In each figure, "▲" represents an etching rate for aluminum, "*" represents an etching rate of the photosensitive film used as an etching mask, and "◆" represents an etching rate for the titanium nitride film.
    First, as shown in FIGS. 5A and 5B, the smaller the source power and the bottom power, the larger the etching selectivity between the aluminum film and the titanium nitride film. In addition, as can be seen in Figure 5c, the mixing ratio of the etching gas BCl 3 and Cl 2 is more the etching selectivity between the aluminum film and the titanium nitride film as the mixing amount of Cl 2 gas than the BCl 3 gas. As shown in FIG. 5D, the higher the pressure, the larger the etching selectivity between the aluminum film and the titanium nitride film.
    An etching process according to an embodiment of the present invention based on the results as described above is as follows.
    First, as a first step etching process, about 80% of the aluminum film is set as an etching end point, thereby etching the antireflection film (Ti / TiN) and the aluminum film. In this case, the first step etching is performed under process conditions in which the source power is 430 to 450 W, the bottom power is 125 to 135 W, the BCl 3 gas amount is 25 to 30 sccm, the Cl 2 gas amount is 60 to 65 sccm, and the pressure is 7 to 9 mTorr.
    Next, as a second step etching process, the etching selectivity between the aluminum film and the diffusion barrier film is increased so that the step of the metal film between the region with a dense pattern and the other regions is not generated. In this case, the second step etching corresponds to a time band of 38 to 43 seconds in FIG. 2 and is performed for about 4 to 6 seconds. In addition, the second step etching is performed under process conditions such that the source power is 350 to 380 W, the bottom power is 50 to 70 W, the amount of BCl 3 gas is 20 to 25 sccm, the amount of Cl 2 gas is 80 to 90 sccm, and the pressure is 13 to 15 mTorr.
    In this case, although not shown, since the etching speed of the aluminum film in the region where the pattern is dense is fast, while the etching rate of the diffusion barrier in the region where the pattern is not dense is slow, the diffusion barriers of the two regions are exposed together. There is no step between the metal films in the two regions.
    Then, as a third step etching process, the metal film, for example, the diffusion barrier film, is etched by an ion sputtering method until the lower insulating film is exposed to form metal wiring. At this time, the third step etching is performed for 25 to 30 seconds, source power 350 to 375 W, bottom power 120 to 130 W, BCl 3 gas amount 25 to 30 sccm, Cl 2 gas amount 40 to 80 sccm, pressure 5 to 6 mTorr. It is carried out in the process conditions to be.
    In the third step etching process, the lower insulating film is not etched in the previous step, and the lower insulating film is etched in the area where the pattern is not dense because the etching is performed by the ion sputtering method where the loading effect phenomenon is relatively small. Can be prevented.
    Therefore, as described above, as the etching process is performed under different process conditions in three steps, the etching of the lower insulating film can be prevented from occurring in a region where the pattern is not dense. The planarization process can be easily performed, whereby the deterioration of characteristics of the semiconductor device can be prevented.
    As described above, the present invention increases the etching selectivity of the diffusion barrier film made of aluminum film and titanium nitride film during the etching process for forming the metal wiring, so that the step between the metal film in the region with a dense pattern and the region without the pattern is increased. Since the lower insulating film can be prevented from being etched in a region where the pattern is not dense during the subsequent over-etching process, the step difference of the lower insulating film can be prevented. A fast process, for example, deposition and planarization of another insulating film can be easily performed.
    In addition, since the etching process is optimized, the reliability of the etching process can be improved, and since the excessive excessive etching process is not performed, damage can be prevented.
    In addition, since the planarization characteristics of the insulating film can be improved in a subsequent step, the insulating characteristics of the device can be improved.
    Meanwhile, although specific embodiments of the present invention have been described and illustrated, modifications and variations can be made by those skilled in the art. Accordingly, the following claims are to be understood as including all modifications and variations as long as they fall within the true spirit and scope of the present invention.
    权利要求:
    Claims (7)
    [1" claim-type="Currently amended] A metal film etching method of a semiconductor device for forming metal wiring by etching a diffusion barrier film, an aluminum film and an antireflection film stacked on an insulating film,
    A first step etching process of etching the anti-reflection film and the aluminum film using about 80% of the aluminum film as an etching end point;
    A second step etching process of etching the remaining aluminum film by increasing the etching selectivity of the aluminum film and the diffusion barrier film, and
    And etching the diffusion barrier layer until the insulating layer is exposed. 3.
    [2" claim-type="Currently amended] The method of claim 1, wherein the first step of the etching process, source power of 430 to 450W, bottom power of 125 to 135W, BCl 3 gas amount of 25 to 30 sccm, Cl 2 gas amount of 60 to 65 sccm, pressure 7 to 9 mTorr Metal film etching method of a semiconductor device, characterized in that carried out under the process conditions.
    [3" claim-type="Currently amended] According to claim 1, The second step etching process, source power 350-380W, bottom power 50-70W, the amount of BCl 3 gas 20-25sccm, the amount of Cl 2 gas 80-90sccm, the pressure 13-15mTorr Metal film etching method of a semiconductor device, characterized in that carried out under the process conditions.
    [4" claim-type="Currently amended] The method of claim 1, wherein the second etching process is performed for 4 to 6 seconds.
    [5" claim-type="Currently amended] According to claim 1, wherein the third step etching process, source power of 350 to 375 W, bottom power of 120 to 130 W, BCl 3 gas amount of 25 to 30 sccm, Cl 2 gas amount of 40 to 80 sccm, pressure 5 to 6 mTorr Metal film etching method of a semiconductor device, characterized in that carried out under the process conditions.
    [6" claim-type="Currently amended] The method of claim 1, wherein the third etching process is performed for 25 to 30 seconds.
    [7" claim-type="Currently amended] The method of claim 1, wherein the etching of the third step is performed by an ion sputtering method.
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    同族专利:
    公开号 | 公开日
    KR100451496B1|2004-12-08|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1998-12-26|Application filed by 김영환, 현대전자산업 주식회사
    1998-12-26|Priority to KR10-1998-0058921A
    2000-07-15|Publication of KR20000042670A
    2004-12-08|Application granted
    2004-12-08|Publication of KR100451496B1
    优先权:
    申请号 | 申请日 | 专利标题
    KR10-1998-0058921A|KR100451496B1|1998-12-26|1998-12-26|Metal film etching method of semiconductor device|
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