KR0171094B1 - Etching method of inter layer insulation film composed of oxide and nitride - Google Patents
Etching method of inter layer insulation film composed of oxide and nitride Download PDFInfo
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- KR0171094B1 KR0171094B1 KR1019950043738A KR19950043738A KR0171094B1 KR 0171094 B1 KR0171094 B1 KR 0171094B1 KR 1019950043738 A KR1019950043738 A KR 1019950043738A KR 19950043738 A KR19950043738 A KR 19950043738A KR 0171094 B1 KR0171094 B1 KR 0171094B1
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- 150000004767 nitrides Chemical class 0.000 title claims abstract description 65
- 239000011229 interlayer Substances 0.000 title claims abstract description 57
- 238000005530 etching Methods 0.000 title claims description 71
- 238000000034 method Methods 0.000 title claims description 35
- 238000009413 insulation Methods 0.000 title description 2
- 239000007789 gas Substances 0.000 claims abstract description 28
- 239000000758 substrate Substances 0.000 claims abstract description 22
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 19
- 239000010703 silicon Substances 0.000 claims abstract description 19
- 239000012495 reaction gas Substances 0.000 claims abstract description 12
- 229920000642 polymer Polymers 0.000 description 10
- 229920002120 photoresistant polymer Polymers 0.000 description 7
- 239000010410 layer Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 229910052731 fluorine Inorganic materials 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001020 plasma etching Methods 0.000 description 3
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000001312 dry etching Methods 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- VDRSDNINOSAWIV-UHFFFAOYSA-N [F].[Si] Chemical compound [F].[Si] VDRSDNINOSAWIV-UHFFFAOYSA-N 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31127—Etching organic layers
- H01L21/31133—Etching organic layers by chemical means
- H01L21/31138—Etching organic layers by chemical means by dry-etching
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31144—Etching the insulating layers by chemical or physical means using masks
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Abstract
본 발명은 실리콘기판 상에 산화막 및 질화막으로 이루어진 층간절연막을 형성하고 상기 층간절연막을 고밀도 플라즈마 장비의 챔버 내에서 식각할 때, 층간절연막 중에서 질화막은 C2F6에 O2가스를 첨가한 반응 가스로 식각하고, 층간절연막 중에서 산화막은 C2F6, C3F9, C4F8중 하나 이상의 반응 가스로 식각하는 것을 특징으로 한다.According to the present invention, when an interlayer insulating film made of an oxide film and a nitride film is formed on a silicon substrate and the interlayer insulating film is etched in a chamber of a high density plasma apparatus, the nitride film of the interlayer insulating film is added with O 2 gas to C 2 F 6 . The oxide film is etched with at least one reaction gas among C 2 F 6 , C 3 F 9 , and C 4 F 8 .
Description
제1도는 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하기 위한 도면.1 is a view for explaining an etching method of an interlayer insulating film made of a conventional oxide film and nitride film.
제2도는 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하기 위한 도면.2 is a view for explaining an etching method of an interlayer insulating film composed of an oxide film and a nitride film according to the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
10,20 : 실리콘기판 11,21 : ON 구조의 층간절연막10,20: silicon substrate 11,21: interlayer insulating film with ON structure
11-1,12-1,12-1',21-1,21-1' : 산화막11-1,12-1,12-1 ', 21-1,21-1': oxide film
11-2,12-2,21-2,21-2' : 질화막11-2,12-2,21-2,21-2 ': nitride film
12 : ONO 구조의 층간절연막 13 : 폴리머12: interlayer insulating film of ONO structure 13: polymer
본 발명은 산화막(oxide)과 질화막(nitride)으로 이루어진 층간절연막의 식각방법에 관한 것으로, 특히 산화막/질화막(oxide/nitride) 또는 산화막/질화막/산화막(oxide/nitride/oxide) 등의 적층 구조를 갖는 층간절연막을 패터닝하여 접촉창(contact hole)을 형성시킴에 있어서 상기 층간절연막의 식각에 적당한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method of an interlayer insulating film consisting of an oxide film and a nitride film, and in particular, a stacked structure of an oxide film / nitride film or an oxide film / nitride film / oxide film The present invention relates to an etching method of an interlayer insulating film comprising an oxide film and a nitride film suitable for etching the interlayer insulating film in forming a contact hole by patterning the interlayer insulating film.
반도체 제조 공정에 있어서, 기판 상에 형성되는 층간절연막을 주로 산화막과 질화막을 서로 적층하여 형성시키고 있으며, 산화막/질화막의 구조(이하, ON 구조라 함) 또는 산화막/질화막/산화막의 구조(이하, ONO 구조라 함)를 갖도록 층간절연막을 형성하고 상기 층간절연막을 고밀도 플라즈마(high density plasma) 장비를 이용한 건식 식각 방법으로 패터닝하여 배선층의 접촉창 또는 캐패시터(capacitor) 전극의 접촉창을 형성시킨다. 이때, 고밀도 플라즈마 장비를 이용한 건식 식각 시에는 질화막 상에 식각 가스(etching gas)와의 반응 부산물로서 접촉창의 식각 진행을 방해하는 폴리머(polymer) 등이 형성된다.In the semiconductor manufacturing process, an interlayer insulating film formed on a substrate is formed by mainly stacking an oxide film and a nitride film, and forming an oxide film / nitride film (hereinafter referred to as an ON structure) or an oxide film / nitride film / oxide film (hereinafter referred to as ONO). The interlayer insulating film is formed to have a structure, and the interlayer insulating film is patterned by a dry etching method using high density plasma equipment to form a contact window of a wiring layer or a contact of a capacitor electrode. At this time, during the dry etching using the high-density plasma equipment, a polymer or the like is formed on the nitride film as a by-product of the reaction with the etching gas, which prevents the etching process of the contact window.
제1도는 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하기 위한 도면으로, 제1도의 (가a)와 (가b)는 ON 구조의 층간절연막의 식각방법을 설명하기 위한 단면도이고, 제1도의 (나a)와 (나b)는 ONO 구조의 층간절연막의 식각방법을 설명하기 위한 단면도이다. 이하 첨부된 도면을 참고로 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하면 다음과 같다.1 is a view for explaining the etching method of a conventional interlayer insulating film consisting of an oxide film and a nitride film, (a) and (b) of Figure 1 is a cross-sectional view for explaining the etching method of the interlayer insulating film of the ON structure, (B) and (b) of FIG. 1 are sectional drawing for demonstrating the etching method of the interlayer insulation film of an ONO structure. Hereinafter, an etching method of an interlayer insulating film made of a conventional oxide film and a nitride film will be described with reference to the accompanying drawings.
종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서는 우선 제1도의 (가a)도에 도시된 바와 같이, 실리콘기판(10)에 산화막(11-1)과 질화막(11-2)이 적층되어 형성된 ON구조의 층간절연막(11)에서는 최상위층인 질화막(11-2) 위에 식각 부위를 정의하는 감광막 패턴(PR ; photoresist pattern)을 형성시키고, 제1도의 (나a)도에 도시된 바와 같이, 실리콘기판(10)에 산화막(12-1)과 질화막(12-2)과 산화막(12-1')이 적층되어 형성된 ONO 구조의 층간절연막(12)에서는 최상위층인 산화막(12-1) 상에 식각 부위를 정의하는 감광막 패턴(PR)을 형성시킨다.In the conventional method of etching an interlayer insulating film made of an oxide film and a nitride film, an oxide film 11-1 and a nitride film 11-2 are stacked on a silicon substrate 10, as shown in FIG. In the formed interlayer insulating film 11 of the ON structure, a photoresist pattern (PR; photoresist pattern) defining an etching portion is formed on the nitride film 11-2, which is the uppermost layer, and as shown in FIG. In the interlayer insulating film 12 of the ONO structure formed by stacking the oxide film 12-1, the nitride film 12-2, and the oxide film 12-1 'on the silicon substrate 10, on the oxide film 12-1 that is the uppermost layer. A photoresist pattern PR is defined to define the etching site.
그리고 ON 구조 또는 ONO 구조의 층간절연막(11)(12)을 식각시키기 위한 반응가스 즉, 식각 가스로서 CHF3, C2F6, C3F8, CH3F, C4F8, CO, CO2등 중에서 한가지 또는 서로 혼합하여 이용하면서, 감광막 패턴(PR)을 마스크(mask)로 하여 산화막(11-1, 12-1, 12-1')과 질화막(11-2, 12-2)을 한 단계(one step)로서 동시에 식각한다.And a reaction gas for etching the interlayer insulating films 11 and 12 of the ON structure or the ONO structure, that is, CHF 3 , C 2 F 6 , C 3 F 8 , CH 3 F, C 4 F 8 , CO, Oxide films 11-1, 12-1, 12-1 'and nitride films 11-2, 12-2 using photosensitive film pattern PR as a mask while using one of CO 2 or the like, or a mixture thereof. Are simultaneously etched as one step.
그러나 높은 종횡비(high aspect ratio)를 가진 접촉창을 형성시킴에 있어서는, 상술한 반응 가스인 CHF3, C2F6, C3F8, CH3F, C4F8, CO, CO2등은 과다한 폴리머를 발생시켜서 폴리머에 의한 높은 식각선택비가 유지되어 과다 식각(over etch)시에 기판 즉, 실리콘기판의 손상이 방지되는 효과를 가지고 있는 반면에, 산화막과 질화막으로 이루어진 층간절연막의 식각 시에는 제1도의 (가b)도와 (나b)도에 도시된 바와 같이, ON 구조 또는 ONO 구조의 층간절연막(11)(12)에서 질화막(11-2)(12-2)에 과다한 폴리머(13)가 증착되어 식각이 중단되는 현상(etching stop)이 발생하게 된다.However, in forming a contact window having a high aspect ratio, the above-mentioned reaction gases CHF 3 , C 2 F 6 , C 3 F 8 , CH 3 F, C 4 F 8 , CO, CO 2, etc. Has an effect of preventing excessive damage to the substrate, i.e., the silicon substrate, during overetch by generating excessive polymer, thereby preventing the damage of the substrate, that is, the silicon substrate, during overetching. As shown in (b) and (b) of FIG. 1, an excessive amount of polymer (e.g., an excessive amount of nitride (11-2) (12-2) in the interlayer insulating film (11) (12) of the ON structure or the ONO structure ( 13) is deposited to cause an etching stop (etching stop) occurs.
즉, 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법에 있어서는, 고밀도 플라즈마 식각 장비에서 식각 가스로서 CHF3, C2F6, C3F8, CH3F, C4F8, CO, CO2등 중에서 한가지 또는 서로 혼합하여 사용할 경우에 질화막 위에 과다한 폴리머가 증착됨에 따라 식각이 전혀 진행되지 않거나, 어느 정도까지만 식각이 진행되다가 멈추는 식각 멈춤(etching stop) 현상이 발생되어서, 배선층 또는 캐패시터 전극의 접촉창 형성시에 접촉창이 불량하게 형성되었다.That is, in the conventional etching method of the interlayer insulating film composed of an oxide film and a nitride film, CHF 3 , C 2 F 6 , C 3 F 8 , CH 3 F, C 4 F 8 , CO, CO as an etching gas in a high density plasma etching equipment In the case of using one of the two or a mixture of two or more of them, as the excessive polymer is deposited on the nitride film, the etching does not proceed at all, or the etching stop occurs when the etching progresses to a certain extent, and thus, the wiring layer or the capacitor electrode The contact window was poorly formed at the time of contact window formation.
특히, 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 이용하여 캐패시터 전극의 접촉창의 형성에 있어서는, 고밀도 플라즈마 식각장비의 챔버(chamber) 내부 온도에 상당히 민감하여 장비 상의 문제로 인하여 불량하게 형성되기도 하였으므로 하드웨어(hardware)적으로도 공정 마진(margin)을 가진 식각 진행조건이 고려되어야 했다.In particular, in the formation of the contact window of the capacitor electrode by using the etching method of the interlayer insulating film made of the conventional oxide film and the nitride film, it is very sensitive to the internal temperature of the chamber of the high density plasma etching equipment and may be poorly formed due to the problem on the equipment. As a result, the etching progression with hardware margin should be considered.
그리고 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서 사용되는 고밀도 플라즈마 식각 장치에 있어서는, 장비의 구조상 챔버 내부의 여러 한정 요소(parameter)들이 과다한 폴리머를 형성시키는데 주요 변수가 되며, 그 중에서 챔버 내에서의 탄소(C)기의 증가는 폴리머 증가의 최대 변수가 되고 있고, 탄소(C)기는 다음과 같은 원인 등에 의해 증가된다.In the high-density plasma etching apparatus used in the conventional method of etching an interlayer insulating film made of an oxide film and a nitride film, various parameters inside the chamber are the main variables for forming an excessive polymer due to the structure of the equipment. The increase in the carbon (C) group at is the maximum variable of the polymer increase, the carbon (C) group is increased by the following causes and the like.
즉, 챔버 내부에서 플라즈마를 형성시키기 위해 2800와트(Watt) 이상의 고전력을 인가하여 사용할 경우에, 주로 탄소-불소(C-F ; Carbon-Flourine)기인 식각 가스의 이온 해리 농도가 높아지기 때문에 탄소(C)기와 불소(F)기가 동시에 증가하게 되며, 또한 탄소(C)기가 많은 반응 가스 즉, C2F6, C3F8, C4F8들은 인가되는 전력의 크기에 비례하여 탄소(C)기의 농도가 더욱 짙어지게 된다.That is, when a high power of 2800 Watt or more is applied to form a plasma inside the chamber, the ion dissociation concentration of the etching gas, which is mainly a carbon-fluorine (CF) group, increases, thereby increasing the carbon (C) group. The fluorine (F) groups increase simultaneously, and the reaction gas containing a lot of carbon (C) groups, that is, C 2 F 6 , C 3 F 8 , C 4 F 8, is proportional to the amount of power applied. The concentration will be thicker.
또한 채버 자체에 있어서는, 챔버의 지붕 내벽이 실리콘 판(silicon plate)으로 되어 있어서, 챔버 내부 온도를 대략 260℃정도로 하면서 식각을 진행시키면, 실리콘 판의 실리콘(Si)이 불소(F)기와 반응하게 되어 실리콘-불소의 화합물(SiFx)이 생성되고, 따라서 상대적으로 탄소(C)가 증가된다.In the chamber, the inner wall of the chamber is made of a silicon plate. When the etching proceeds while the chamber temperature is about 260 ° C., the silicon (Si) of the silicon plate reacts with the fluorine (F) group. This results in the formation of a silicon-fluorine compound (SiFx), thus increasing the carbon (C) relatively.
즉, 종래의 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서는 산화막과 질화막을 한 단계로서 식각시킬 때에 질화막으로 식각 가스의 반응 부산물이 폴리머가 과다하게 증착되어 식각이 전혀 진행되지 않거나, 어느 정도까지만 식각이 진행되다가 멈추는 식각 멈춤 현상이 발생되는 문제가 있다.That is, in the conventional etching method of the interlayer insulating film formed of the oxide film and the nitride film, when the oxide film and the nitride film are etched as one step, the reaction by-products of the etching gas are excessively deposited on the nitride film so that the etching does not proceed at all, or only to some extent, the etching process is performed. There is a problem that the etch stop phenomenon occurs during this progress.
본 발명은 이러한 종래의 문제점을 해결하기 위하여 안출된 것으로, 종래의 한 단계로 진행되는 식각 진행을 두 단계(two step)로 진행시키되, 질화막의 식각이 용이하고, 또한 실리콘기판의 손상을 감소되는 층간절연막의 식각 방법을 제공하고자 하는 것이 그 목적이다.The present invention has been made to solve such a conventional problem, and proceeds the etching proceeding in one step in the conventional two steps (two steps), the etching of the nitride film is easy, and also damage to the silicon substrate is reduced An object of the present invention is to provide an etching method of an interlayer insulating film.
본 발명은 실리콘기판 상에 형성되고, 고밀도 플라즈마 장비의 챔버 내에서 진행되는 산화막과 질화막으로 이루어진 층간절연막의 식각방법에 있어서, 층간절연막에서 질화막을 C2F6에 O2가스를 첨가한 반응 가스로 식각시키는 단계와, 층간절연막에서 산화막을 C2F6, C3F8, C4F8중 하나 이상의 반응 가스로 식각시키는 단계를 포함하여 이루어진다.The present invention is formed on a silicon substrate, a high-density plasma in the etching process of the interlayer insulating film made of an oxide film and nitride film are conducted in the chamber of the equipment, addition of O 2 gas to the nitride film on the interlayer insulating film on C 2 F 6 reaction gas And etching the oxide film with at least one of C 2 F 6 , C 3 F 8 , and C 4 F 8 reactant gas in the interlayer insulating film.
제2도는 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하기 위한 도면으로, 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법의 일실시예로 ON 구조의 층간절연막의 식각방법의 단계를 도시한 단면도이다. 이하 첨부된 도면을 참고로 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법을 설명하면 다음과 같다.2 is a view for explaining an etching method of an interlayer insulating film composed of an oxide film and a nitride film according to the present invention, an etching method of an interlayer insulating film having an ON structure as an embodiment of the etching method of the interlayer insulating film consisting of an oxide film and a nitride film according to the present invention. A cross section showing the steps of the method. Hereinafter, an etching method of an interlayer insulating film made of an oxide film and a nitride film according to the present invention will be described with reference to the accompanying drawings.
본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서 ON 구조의 층간절연막의 식각방법에서는 우선, 제2도의 (a)에 도시된 바와 같이, 실리콘기판(20) 상에 산화막(21-1)과 질화막(21-2)이 적층되어 형성된 ON 구조의 층간절연막(21)에서 최상위층인 질화막(21-2) 위에 식각 부위를 정의하는 감광막 패턴(PR')을 형성시킨다.In the etching method of the interlayer insulating film of the interlayer insulating film made of the oxide film and the nitride film according to the present invention, first, as shown in Fig. 2A, the oxide film 21-1 is formed on the silicon substrate 20. ) And a photoresist pattern PR ′ defining an etched portion is formed on the nitride film 21-2, which is the uppermost layer, in the interlayer insulating film 21 having the ON structure formed by stacking the layer 1) and the nitride film 21-2.
이어서 제2도의 (b)에 도시된 바와 같이, 감광막 패턴(PR')을 마스크로 하면서, ON 구조의 층간절연막(21)에서 질화막(21-2')을 C2F6에 O2가스를 첨가한 반응 가스로 식각시킨다.Then the O 2 gas, a photoresist pattern (PR '), (a, a nitride film 21-2) in the interlayer insulating film 21 as a mask while the structure of the ON' to C 2 F 6, as shown in the second degree (b) It is etched with the added reaction gas.
이때, 반응 가스는 25∼30[sccm] 정도의 C2F6가스에 5[sccm] 정도의 O2가스를 첨가한 것을 이용한다.In this case, reaction gas is used in the addition of O 2 gas of about 5 [sccm] to C 2 F 6 gas of about 25~30 [sccm].
그 다음에는 제2도의 (c)에 도시된 바와 같이, ON 구조의 층간절연막(21)에서 상기 질화막이 제거되어 노출된 산화막(21-1')을 C2F6, C3F8, C4F8중 하나 이상의 반응 가스로 식각시켜서 식각 부위의 기판을 노출시킨다.Next, as illustrated in FIG. 2C, the nitride film is removed from the interlayer insulating film 21 having an ON structure to expose the exposed oxide film 21-1 ′, C 2 F 6 , C 3 F 8 , C 4 F 8 by etching with at least one reaction gas of the substrate to expose the etching regions.
이때, 기판과 접하면서 형성된 산화막을 식각시키는 반응 가스는 40∼50[sccm] 정도의 유량 범위를 갖는 C2F6, C3F8, C4F8중 하나 이상을 이용한다.In this case, at least one of C 2 F 6 , C 3 F 8 , and C 4 F 8 having a flow rate range of about 40 to 50 [sccm] is used as a reaction gas for etching the oxide film formed while contacting the substrate.
그리고 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서 식각 마스크로 사용되는 감광막 패턴의 두께는 O2가스에 의해 점점 얇아지게 되므로, 이를 고려하여 감광막 패턴을 형성시키며, 고밀도 플라즈마 장비의 한정 요소에 의한 폴리머의 발생을 최대한으로 억제시키기 위하여 장비에서 챔버 내부의 온도는 그 최소값을 종래 기술에서의 챔버 내부 온도 보다 약 10℃ 이상 낮추면서 즉, 220℃에서 230℃ 정도가 되도록 하면서 최대 약 285℃ 정도의 온도 범위로 조정하면서 진행시킨다.The thickness of the photoresist pattern used as an etch mask in the etching method of the interlayer insulating film composed of the oxide film and the nitride film according to the present invention becomes thinner by O 2 gas, thus forming the photoresist pattern in consideration of this, and limiting the density of the high density plasma equipment. In order to minimize the generation of polymers by urea, the temperature inside the chamber in the equipment is at most about 285 while keeping its minimum value at least about 10 ° C. lower than the temperature inside the chamber in the prior art, ie from 220 ° C. to 230 ° C. It advances, adjusting to the temperature range of about degreeC.
본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서, 질화막과 산화막의 식각에 있어서는 상기 질화막과 산화막을 한 단계로 식각하는 것보다 질화막과 산화막을 각기 식각시키는 두 단계로 식각을 진행시킨다.In the etching method of the interlayer insulating film made of the oxide film and the nitride film according to the present invention, in the etching of the nitride film and the oxide film, the etching is performed in two steps of etching the nitride film and the oxide film, respectively, rather than etching the nitride film and the oxide film in one step.
즉, 질화막은 C2F6에 O2가스를 첨가한 반응 가스를 이용하여 식각시키고, 산화막의 식각 시에는 실리콘기판과의 식각선택비가 높은 반응 가스 즉, C2F6, C3F8, C4F8등의 가스를 이용하여 실리콘기판의 손상을 최대한으로 감소시킬 수 있다.That is, the nitride film is etched using a reaction gas in which O 2 gas is added to C 2 F 6 , and when the oxide film is etched, it is a reactive gas having a high etching selectivity with a silicon substrate, that is, C 2 F 6 , C 3 F 8 , Gases such as C 4 F 8 can be used to minimize damage to the silicon substrate.
이때, 산화막에 위에 형성된 질화막의 식각에 있어서는 질화막에 대한 산화막의 식각선택비가 약 4 : 1 이하의 비율로 낮춰지게 되어 식각이 용이하게 진행되면서, 실리콘기판과 접하여 형성된 산화막은 40∼50[sccm] 정도의 유량 범위를 갖는 C2F6, C3F8, C4F8등의 가스를 이용한 식각진행시에 실리콘기판에 대한 산화막의 식각선택비는 약 25 : 1 이상의 비율로 높아지므로, 실리콘기판의 손실이 저하된다.At this time, in the etching of the nitride film formed on the oxide film, the etching selectivity of the oxide film to the nitride film is lowered at a ratio of about 4: 1 or less, so that the etching is easily performed, and the oxide film formed in contact with the silicon substrate is 40 to 50 [sccm]. Since the etching selectivity of the oxide film to the silicon substrate is increased at a ratio of about 25: 1 or more during the etching process using gases such as C 2 F 6 , C 3 F 8 , C 4 F 8, etc. The loss of the substrate is reduced.
또한 종래의 기술에서 C2F6, C3F8등의 가스에 O2가스를 첨가할 때 C2F6, C3F8가스의 유량에 따라 질화막에 증착되어 형성되는 폴리머에 의한 식각 멈춤(etch stop) 현상이 발생하게 되는데, 특히 C2F6가스 또는 C3F8가스를 약 40[sccm] 정도의 유량으로 사용할 때에는 식각 멈춤 현상이 현저하게 발생되므로, C2F6가스 또는 C3F8가스를 약 25∼30[sccm] 정도로 사용하면서 챔버 내부의 온도를 220℃에서 250℃의 범위로 변화시키면서 진행시키면서 진행시키면 질화막의 식각시에 안정적인 공정 마진을 확보할 수 있다.Further etch stop by the polymer that is formed by depositing a nitride film according to the flow rate of C 2 F 6, C 3 F 8 gas upon the addition of the O 2 gas to the gas such as C 2 F 6, C 3 F 8 in the prior art (etch stop) phenomenon occurs, especially when using a C 2 F 6 gas or C 3 F 8 gas at a flow rate of about 40 [sccm], because the etch stop is remarkably generated, C 2 F 6 gas or C By using the 3 F 8 gas at about 25 to 30 [sccm] while advancing while changing the temperature in the chamber in the range of 220 ° C. to 250 ° C., a stable process margin can be secured when the nitride film is etched.
그리고 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서 ONO 구조의 층간절연막을 식각시킬때에는 최상위 산화막을 C2F6, C3F8, C4F8등의 가스를 이용하되, 챔버 내부의 온도를 220℃에서 285℃의 범위로 변화시키면서 풀리머 생성이 억제된 조건하에서 제거한 후에 질화막과 최하위 산화막을 상술한 방법으로 식각하면 된다.In the etching method of the interlayer insulating film made of the oxide film and the nitride film according to the present invention, when etching the interlayer insulating film of the ONO structure, the gas of the top oxide film is C 2 F 6 , C 3 F 8 , C 4 F 8, etc. The nitride film and the lowest oxide film may be etched by the above-described method after removing the internal temperature in a range of 220 ° C. to 285 ° C. under the condition that the generation of the primer is suppressed.
본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서는 고밀도 플라즈마 장비에 있어서, 종래의 질화막에 증착되어 형성되는 폴리머에 의한 식각 멈춤 현상이 방지되므로 질화막에 대한 식각 특성이 향상되며, 또한 질화막에 대한 산화막의 식각선택비(약 25 : 1 이상)를 높일 수 있으므로, 질화막의 식각이 용이하게 진행되면서 실리콘기판의 손상을 억제시킬 수 있다.In the etching method of the interlayer insulating film made of the oxide film and the nitride film according to the present invention, in the high-density plasma equipment, the etch stop phenomenon caused by the polymer deposited on the conventional nitride film is prevented, so that the etching characteristics of the nitride film are improved. Since the etching selectivity (about 25: 1 or more) of the oxide film can be increased, the etching of the nitride film can be easily performed and the damage to the silicon substrate can be suppressed.
또한 본 발명에 의한 산화막과 질화막으로 이루어진 층간절연막의 식각방법에서는 고밀도 플라즈마 장비의 하드웨어적인 불안정에도 챔버 내부의 온도를 변화시키면서 식각을 진행시키므로 안정적인 식각이 진행되게 된다.In addition, in the etching method of the interlayer insulating film made of the oxide film and the nitride film according to the present invention, the etching process is performed while changing the temperature inside the chamber despite the hardware instability of the high density plasma equipment.
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