KR19980065500A - Etch gas of ferroelectric film - Google Patents
Etch gas of ferroelectric film Download PDFInfo
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- KR19980065500A KR19980065500A KR1019970000523A KR19970000523A KR19980065500A KR 19980065500 A KR19980065500 A KR 19980065500A KR 1019970000523 A KR1019970000523 A KR 1019970000523A KR 19970000523 A KR19970000523 A KR 19970000523A KR 19980065500 A KR19980065500 A KR 19980065500A
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- 238000005530 etching Methods 0.000 claims abstract description 97
- 239000007789 gas Substances 0.000 claims abstract description 73
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910000042 hydrogen bromide Inorganic materials 0.000 claims abstract description 21
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000004065 semiconductor Substances 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 10
- 239000002184 metal Substances 0.000 claims abstract description 10
- 229910052786 argon Inorganic materials 0.000 claims abstract description 7
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 claims abstract description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 41
- 238000002347 injection Methods 0.000 claims description 17
- 239000007924 injection Substances 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 13
- 229910052697 platinum Inorganic materials 0.000 claims description 12
- 239000003870 refractory metal Substances 0.000 claims description 6
- 229920002120 photoresistant polymer Polymers 0.000 claims description 5
- 229910052726 zirconium Inorganic materials 0.000 claims description 5
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 3
- 229920005591 polysilicon Polymers 0.000 claims description 3
- 229910021332 silicide Inorganic materials 0.000 claims description 3
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 claims description 3
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 claims description 2
- 229910052741 iridium Inorganic materials 0.000 claims description 2
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052746 lanthanum Inorganic materials 0.000 claims description 2
- 229910044991 metal oxide Inorganic materials 0.000 claims description 2
- 150000004706 metal oxides Chemical class 0.000 claims description 2
- 239000010408 film Substances 0.000 abstract description 48
- 239000010409 thin film Substances 0.000 abstract description 6
- 239000000203 mixture Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
- H01L21/67063—Apparatus for fluid treatment for etching
- H01L21/67069—Apparatus for fluid treatment for etching for drying etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- 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
- H01L21/31122—Etching inorganic layers by chemical means by dry-etching of layers not containing Si, e.g. PZT, Al2O3
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Drying Of Semiconductors (AREA)
Abstract
아르곤 가스(Ar), 브롬화 수소 가스(HBr) 및 사불화 탄소 가스(CF4)를 포함하는 반도체 장치의 강유전막 식각 가스에 있어서, CHF3가스를 더 포함하여 강유전막과 내열성 금속에 대해 높은 식각 선택비를 갖는 것을 특징으로 하는 반도체 장치의 강유전막 식각 가스가 개시된다.In a ferroelectric film etching gas of a semiconductor device including argon gas (Ar), hydrogen bromide gas (HBr), and carbon tetrafluoride gas (CF 4 ), the etching of the ferroelectric film and the heat resistant metal further includes a CHF 3 gas. Disclosed is a ferroelectric film etching gas of a semiconductor device having a selectivity ratio.
본 발명에 의하면, 강유전막의 과도 식각에 따른 전극 박막의 손상과 절연 산화막의 피팅(pitting)현상 및 두께 불균일을 방지할 수 있으므로 신뢰성 높은 반도체 소자를 제조할 수 있다.According to the present invention, it is possible to prevent damage to the electrode thin film due to excessive etching of the ferroelectric film, pitting phenomenon and thickness nonuniformity of the insulating oxide film, so that a highly reliable semiconductor device can be manufactured.
Description
DRAM(Dynamic Random Access Memory)의 집적도가 증가함에 따라, 제한된 셀 면적내에서 캐패시턴스를 증가시키기 위한 많은 방법들이 제안되고 있는데, 보통 다음의 세 가지로 나뉘어질 수 있다. 즉, ① 유전막을 박막화하는 방법, ② 커패시터의 유효면적 증가를 위해 커패시터 구조를 입체화시키는 방법, 및 ③ 유전 상수가 큰 물질을 사용하는 방법이 그것이다.As the density of dynamic random access memory (DRAM) increases, many methods for increasing capacitance within a limited cell area have been proposed, and can be generally divided into three types. That is, ① a method of thinning the dielectric film, ② a method of dimensionalizing the capacitor structure to increase the effective area of the capacitor, and ③ a method of using a material having a large dielectric constant.
이 중, 첫 번째 방법은 유전막의 두께를 100Å 이하로 박막화하는 경우 파울러 노드하임(Fowler-Nordheim) 전류에 의해 신뢰성이 저하되므로 대용량 메모리 소자에 적용하기가 어렵다는 단점이 있다.Among these, the first method has a disadvantage in that it is difficult to apply to a large-capacity memory device because the reliability is degraded by the Fowler-Nordheim current when the thickness of the dielectric film is less than 100Å.
두 번째 방법은, 실린더 및 핀(Fin)형과 같은 3차원 구조의 커패시터를 제조하기 위하여 공정이 복잡해지고 공정 단가가 증가하게 되는 단점이 있다.The second method has a disadvantage in that the process becomes complicated and the process cost increases to manufacture a three-dimensional capacitor such as a cylinder and a fin.
따라서, 최근에는 세 번째 방법, 즉, 기존의 실리콘 산화막이나 실리콘 산화막과 실리콘 질화막의 적층구조로 형성된 유전막과는 달리 자발 분극(spontaneous polarization) 현상을 갖고, 이들 보다 유전 상수가 보통 수백에서 1,000배 이상인 페로브스카이트(perovskite) 구조의 강유전 물질(ferroelectric material), 예컨대 PZT (Pb(Zr,Ti)O3)이나 BST (Ba(Sr,Ti)O3), STO((Sr,Ti)O3)등을 유전막으로 사용하는 방법이 채택되고 있다. 이때, 강유전막 커패시터의 전극은 고온의 산소 분위기에서도 산화되지 않고, 특성이 우수한 페로브스카이트 구조의 유전막 형성을 가능하게 하는 백금족 원소 예를 들면, 백금 (Pt: platinum)으로 형성된다.Therefore, recently, the third method, that is, unlike the conventional dielectric film formed of a silicon oxide film or a laminated structure of a silicon oxide film and a silicon nitride film, has a spontaneous polarization phenomenon, and the dielectric constant is usually several hundred to 1,000 times or more than these. Ferroelectric materials of the perovskite structure, such as PZT (Pb (Zr, Ti) O 3 ), BST (Ba (Sr, Ti) O 3 ), STO ((Sr, Ti) O 3 Has been adopted as a dielectric film. At this time, the electrode of the ferroelectric film capacitor is formed of a platinum group element, for example, platinum (Pt), which does not oxidize even in a high temperature oxygen atmosphere and enables the formation of a dielectric film having a perovskite structure with excellent characteristics.
강유전막 예를 들어 PZT는 일반적으로 졸-겔 스핀 온 코팅(SOL-GEL Spin On Coating) 방법으로 증착되는데, 졸-겔 스핀 온 코팅법에 의하면 하부 막질의 단차 구조(topography)와는 상관없이 평탄하게 막이 형성된다.Ferroelectric films, such as PZT, are generally deposited by SOL-GEL Spin On Coating, and sol-gel spin-on coating, which is flat regardless of the topography of the underlying film. A film is formed.
도 1은 졸-겔(SOL-GEL) 스핀 온 코팅(Spin On Coating)법에 의하여 백금 하부 전극상에 형성된 PZT층의 단면을 도시한다. 여기서, 참조 번호 10과 12는 각각 절연 산화막과 게이트 전극을 나타내며, 참조 번호 14와 16은 각각 백금막과 PZT막을 나타낸다.FIG. 1 shows a cross section of a PZT layer formed on a platinum lower electrode by a sol-gel (SOL-GEL) spin on coating method. Here, reference numerals 10 and 12 denote insulating oxide films and gate electrodes, respectively, and reference numerals 14 and 16 denote platinum films and PZT films, respectively.
따라서 졸-겔 스핀 온 코팅(SOL-GEL Spin On Coating)법으로 형성된 PZT 강유전막을 식각하는 경우에, 단차가 깊은 부위의 PZT를 제거하기 위해서는 과도 식각을 해야 하며 이때 PZT와 하부 막질과의 식각 선택비가 나쁘면 장시간의 과도 식각에 의해 하부 막질이 손상된다.Therefore, in case of etching PZT ferroelectric film formed by SOL-GEL Spin On Coating method, it is necessary to over-etch in order to remove PZT in the deep step area. If the rain is bad, the lower film quality is damaged by long time excessive etching.
종래의 식각 가스는 백금족 원소 예를 들어, 백금(Pt)로 이루어진 박막과 강유전막 예를 들어, PZT에 대해서 거의 동일한 식각율을 가지므로 PZT막의 식각 공정에서 하부에 존재하는 백금막과 절연 산화막이 상당량 식각되었으며, 이로 인해서 피팅(pitting) 현상이나 하부 막질의 두께 불균일 현상이 발생하는 문제가 있었다.Conventional etching gas has a nearly identical etching rate for a thin film made of a platinum group element, for example, platinum (Pt) and a ferroelectric film, for example, PZT. It was etched in a significant amount, which causes a problem of pitting or uneven thickness of the lower film.
본 발명의 기술적 과제는 강유전막과 백금족 금속 박막에 대해 높은 식각 선택비를 갖는 식각 가스를 제공하는 것이다.The technical problem of the present invention is to provide an etching gas having a high etching selectivity for the ferroelectric film and the platinum group metal thin film.
도 1은 백금 하부 전극상에 졸-겔(SOL-GEL) 스핀 온 코팅(Spin On Coating)법에 의하여 형성된 PZT 유전층의 단면을 보여주는 주사 전자 현미경(SEM) 사진이다.FIG. 1 is a scanning electron microscope (SEM) image showing a cross section of a PZT dielectric layer formed by a SOL-GEL spin on coating method on a platinum lower electrode.
도 2는 종래의 강유전막 식각 가스의 식각 선택비 (selectivity)를 보이는 그래프이다.2 is a graph showing an etching selectivity of a conventional ferroelectric film etching gas.
도 3은 본 발명에 따르는 강유전막 식각 가스의 식각 선택비를 보이는 그래프이다.3 is a graph showing the etching selectivity of the ferroelectric film etching gas according to the present invention.
본 발명의 기술적 과제를 달성하기 위하여 아르곤 가스(Ar), 브롬화 수소 가스(HBr) 및 사불화 탄소 가스(CF4)를 포함하는 반도체 장치의 강유전막 식각 가스에 있어서, CHF3가스를 더 포함하여 강유전막과 백금족 금속 박막에 대해 높은 식각 선택비를 갖는 것을 특징으로 하는 반도체 장치의 강유전막 식각 가스가 제공된다.In the ferroelectric film etching gas of a semiconductor device including argon gas (Ar), hydrogen bromide gas (HBr) and carbon tetrafluoride gas (CF 4 ) in order to achieve the technical problem of the present invention, further comprising a CHF 3 gas A ferroelectric film etching gas of a semiconductor device is provided which has a high etching selectivity with respect to a ferroelectric film and a platinum group metal thin film.
이하, 본 발명에 대해 상세히 설명한다.Hereinafter, the present invention will be described in detail.
강유전막, 예를 들어 PZT의 건식 식각 공정에서, 식각 선택비에 영향을 미치는 요소는 크게 식각 가스의 종류, 식각 가스량, 챔버내의 압력, KHz 파워(KHz power) 및 MHz 파워(MHz power) 등을 들 수 있다.In the dry etching process of ferroelectric films, such as PZT, the factors affecting the etching selectivity are largely determined by the type of etching gas, the amount of etching gas, the pressure in the chamber, the KHz power and the MHz power. Can be mentioned.
본 발명에서는, 백금족 금속 박막과 강유전막의 식각 선택비에 가장 큰 영향을 미치는 인자가 무엇인지를 찾기 위해 몇 가지 실험을 실시하였다.In the present invention, several experiments were conducted to find out what factors have the greatest influence on the etching selectivity of the platinum group metal thin film and the ferroelectric film.
먼저, 소정의 패턴이 형성된 반도체 기판상에 졸-겔 스핀 온 글래스법으로 PZT를 도포하여 강유전막을 형성한다. 이어서, 상기 결과물상에 유기 포토레지스트(organic photoresist)로 식각 마스크를 형성하여 제1 시료를 준비한다.First, PZT is applied to a semiconductor substrate on which a predetermined pattern is formed by a sol-gel spin on glass method to form a ferroelectric film. Subsequently, an etching mask is formed of an organic photoresist on the resultant to prepare a first sample.
여기서, 상기 강유전막은 PLZT((Pb,La)(Zr,Ti)O3) 또는 PNZT(Pb(Nb)(Zr,Ti)O3)로도 형성할 수 있다. 또한, 상기 식각 마스크 패턴은 내열성 금속(refractory metal), 내열성 금속의 실리사이드(silicide), 내열성 금속의 산화물(refractory metal oxide), 또는 폴리실리콘(polysilicon) 등으로도 형성할 수 있다.The ferroelectric film may be formed of PLZT ((Pb, La) (Zr, Ti) O 3 ) or PNZT (Pb (Nb) (Zr, Ti) O 3 ). In addition, the etching mask pattern may be formed of a refractory metal, a silicide of the heat resistant metal, an oxide of the heat resistant metal, a polysilicon, or the like.
다음에, 또 다른 반도체 기판상에 스퍼터링(sputtering)에 의해 백금(Pt)을 증착한 후, 상기 결과물상에 유기성 포토레지스트로 식각 마스크를 형성하여 제2 시료를 준비한다.Next, after depositing platinum (Pt) on another semiconductor substrate by sputtering, an etching mask is formed of an organic photoresist on the resultant to prepare a second sample.
여기서, 상기 전극은 이리듐(Ir) 또는 산화 이리듐(IrO2)으로 형성할 수도 있다. 또한, 제1 시료와 마찬가지로, 상기 제2 시료의 식각 마스크도 내열성 금속(refractory metal), 내열성 금속의 실리사이드(silicide), 내열성 금속의 산화물(refractory metal oxide) 또는 폴리실리콘(polysilicon) 등으로 형성할 수 있다.The electrode may be formed of iridium (Ir) or iridium oxide (IrO 2 ). In addition, like the first sample, the etching mask of the second sample may be formed of a refractory metal, a silicide of the heat resistant metal, a refractory metal oxide, polysilicon, or the like. Can be.
이어서, 다음과 같은 실험 조건하에서 상기 제1 및 제2 시료를 반응성 이온 식각으로 60초 동안 식각한 후 상기 유기 포토레지스트 마스크를 각각 제거한다. 그후에, 스타일러스 계측기(stylus gauge) α-step을 이용하여 백금막과 PZT막의 식각율을 측정한다.Subsequently, the first and second samples are etched by reactive ion etching for 60 seconds under the following experimental conditions, and then the organic photoresist mask is removed. The etch rate of the platinum film and PZT film is then measured using a stylus gauge α-step.
제1 실험예Experimental Example
아르곤 가스의 주입량과 MHz 파워(MHz power)를 고정한 상태에서 식각 가스의 조성, 식각 챔버내의 압력 및 KHz 파워(KHz power)의 변화에 따른 식각 선택비의 변화를 관찰하였다.The change in the etch selectivity according to the composition of the etching gas, the pressure in the etching chamber, and the KHz power was observed with the argon gas injection rate and the MHz power fixed.
식각 가스의 일 구성 성분인 아르곤 가스의 주입량을 10sccm로 하고 MHz 파워(MHz power)를 500W로 고정한 다음, CF4가스와 HBr 가스의 조성비, 식각 챔버내의 압력 및 KHz 파워(KHz power)를 각각 변화시키면서 상기 제1 및 제2 시료의 PZT막과 백금막을 식각하여 표 1과 같은 결과를 얻었다.Argon gas, a component of the etching gas, was injected at 10 sccm and the MHz power was fixed at 500 W. Then, the composition ratio of CF 4 gas and HBr gas, the pressure in the etching chamber, and the KHz power (KHz power) were changed. While etching the PZT film and the platinum film of the first and second samples were obtained as shown in Table 1.
표 1Table 1
제1 비교예Comparative Example 1
CF4가스와 HBr 가스의 조성비에 따른 PZT막과 백금막의 식각 선택비 변화를 알아보기위해 상기 제2 조건과 제6 조건에서의 식각 선택비 및 제5 조건과 제7 조건에서의 식각 선택비를 각각 비교해 본다.In order to determine the change in the etching selectivity of the PZT film and the platinum film according to the composition ratio of CF 4 gas and HBr gas, the etching selectivity in the second and sixth conditions and the etching selectivity in the fifth and seventh conditions Compare each.
먼저, 제2 조건과 제6 조건에서의 식각 선택비를 비교한다.First, the etching selectivity in the second condition and the sixth condition is compared.
식각 챔버내의 압력 및 KHz 파워(KHz power)를 각각 5 mTorr와 100W로 고정했을 때, CF4가스 주입량과 HBr가스 주입량의 비가 1:3인 제2 조건하에서 Pt에 대한 PZT의 식각 선택비는 0.67이며 CF4가스 주입량과 HBr가스 주입량이 3:1인 제6 조건하에서 식각 선택비는 보다 높은 1.03으로 나타났다.When the pressure and KHz power in the etching chamber were fixed at 5 mTorr and 100 W, respectively, the etching selectivity ratio of PZT to Pt was 0.67 under the second condition where the ratio of CF 4 gas injection and HBr gas injection was 1: 3. In addition, the etching selectivity was higher than 1.03 under the sixth condition in which the CF 4 gas injection amount and the HBr gas injection amount were 3: 1.
한편, 제5 조건과 제7 조건에서의 식각 선택비를 비교한다.On the other hand, the etching selectivity under the fifth condition and the seventh condition is compared.
식각 챔버내의 압력 및 KHz 파워(KHz power)를 각각 30mTorr와 300W로 고정했을 때, CF4가스 주입량과 HBr가스 주입량의 비가 1:3인 제5 조건하에서 식각 선택비는 1.04였으며, CF4가스 주입량과 HBr가스 주입량의 비가 3:1인 제6 조건하에서 식각 선택비는 보다 낮아진 0.55였다.At a fixed pressure and KHz power (KHz power) in the etch chamber to each of 30mTorr and 300W, CF 4 gas injection amount and the ratio of HBr gas injection amount: 3 or the etching selectivity under the 5 conditions was 1.04, CF 4 gas injection amount The etching selectivity was lower, 0.55, under the sixth condition in which the ratio of HBr injection ratio was 3: 1.
상기 결과로부터, CF4가스와 HBr가스의 조성비는 식각 선택비에 큰 영향을 미치지 않는다고 할 수 있다. 동일한 결론을 제1 조건과 제8 조건을 비교함으로써 얻을 수 있다.From the above results, it can be said that the composition ratio of CF 4 gas and HBr gas does not significantly affect the etching selectivity. The same conclusion can be obtained by comparing the first and eighth conditions.
또한, 이러한 사실은 도2에 나타난 그래프에서도 보여진다.This fact is also shown in the graph shown in FIG.
제2 비교예2nd comparative example
식각 챔버내의 압력 변화에 따른 식각 선택비의 변화를 알아보기 위해서 상기 제1 조건과 제7 조건, 그리고 제2 조건과 제3 조건하에서의 식각 선택비를 각각 비교해 본다.In order to determine the change in the etching selectivity according to the pressure change in the etching chamber, the etching selectivity under the first condition, the seventh condition, and the second condition and the third condition is compared.
먼저, 제1 조건과 제7 조건하에서의 식각 선택비를 비교한다.First, the etching selectivity under the first condition and the seventh condition is compared.
식각 챔버내의 CF4:HBr의 조성비와 KHz 파워는 각각 3:1과 300W로 고정된다. 이때, 식각 챔버내의 압력이 5mTorr인 제1 조건하에서 식각 선택비는 1.13인 반면, 식각 챔버내의 압력이 30mTorr로 보다 높은 제7 조건하에서의 식각 선택비는 0.55로 보다 낮아졌다.The composition ratio of CF 4 : HBr and the KHz power in the etching chamber are fixed at 3: 1 and 300W, respectively. At this time, the etching selectivity was 1.13 under the first condition in which the pressure in the etching chamber was 5 mTorr, while the etching selectivity under the seventh condition in which the pressure in the etching chamber was 30 mTorr was lowered to 0.55.
이어서, 제2 및 제3 조건에서의 식각 선택비를 비교한다.Next, the etching selectivity in the second and third conditions is compared.
식각 가스중의 CF4:HBr의 조성비와 KHz 파워는 각각 1:3 과 100W로 고정한다. 이때, 식각 챔버내의 압력이 5 mTorr인 제2 조건에서는 식각 선택비가 0.67 이었으며 식각 챔버내의 압력이 30mTorr로 보다 높아진 제3 조건에서는 식각 선택비가 0.6로서 보다 낮아졌다.The composition ratio of CF 4 : HBr and the KHz power in the etching gas are fixed at 1: 3 and 100W, respectively. In this case, the etching selectivity was 0.67 in the second condition where the pressure in the etching chamber was 5 mTorr, and the etching selectivity was lower as 0.6 in the third condition in which the pressure in the etching chamber was higher than 30 mTorr.
상기 결과로부터, 식각 챔버내의 압력이 낮을수록 백금막에 대한 PZT막의 식각 선택비가 커짐을 알 수 있다.From the above results, it can be seen that the lower the pressure in the etching chamber, the larger the etching selectivity of the PZT film relative to the platinum film.
동일한 결론을 제4 조건과 제6 조건에서의 식각 선택비를 비교함으로써 얻을 수 있다.The same conclusion can be obtained by comparing the etching selectivity in the fourth and sixth conditions.
제3 비교예Third Comparative Example
KHz 파워의 변화에 따른 식각 선택비의 변화를 알아보기 위해서 제2 조건과 제8 조건하에서의 식각 선택비를 비교하고, 제1 조건과 제6 조건에서의 식각 선택비를 비교해 본다.In order to determine the change in the etching selectivity according to the change in the KHz power, the etching selectivity under the second condition and the eighth condition is compared, and the etching selectivity under the first condition and the sixth condition is compared.
먼저, 제2 및 제8 조건에서의 식각 선택비를 비교한다.First, the etching selectivity in the second and eighth conditions is compared.
식각 가스중의 CF4:HBr의 조성비와 식각 챔버내의 압력을 각각 1:3 및 5 mTorr로 고정한다. 이때, KHz 파워가 100W인 제2 조건하에서 식각 선택비는 0.67로 나타났으며 KHz 파워가 300W로서 보다 높아진 제8 조건에서는 식각 선택비 또한 0.97로 높게 나타났다.The composition ratio of CF 4 : HBr in the etching gas and the pressure in the etching chamber are fixed at 1: 3 and 5 mTorr, respectively. At this time, the etching selectivity was 0.67 under the second condition with a KHz power of 100W, and the etching selectivity was also high as 0.97 under the eighth condition when the KHz power was higher as 300W.
이어서, 제4 조건과 제7 조건하에서의 식각 선택비를 비교한다.Subsequently, the etching selectivity under the fourth condition and the seventh condition is compared.
식각 가스중의 CF4:HBr의 조성비와 챔버내의 압력을 각각 3:1 및 30mTorr로 고정한다. 이때, KHz 파워가 100W인 제4 조건하에서 식각 선택비는 0.54로 나타났으며, KHz 파워가 300W로 보다 높아진 제7 조건하에서는 식각 선택비가 0.55로 높아졌다.The composition ratio of CF 4 : HBr in the etching gas and the pressure in the chamber are fixed at 3: 1 and 30 mTorr, respectively. At this time, the etch selectivity was 0.54 under the fourth condition where the KHz power was 100W, and the etch selectivity was increased to 0.55 under the seventh condition when the KHz power was higher than 300W.
상기 결과로부터, KHz 파워가 높을수록 백금막에 대한 PZT막의 식각 선택비가 커짐을 알 수 있으며, 제3 조건과 제5 조건하에서의 식각 선택비를 비교하는 경우에도 동일한 결론을 얻을 수 있다.From the above results, it can be seen that the higher the KHz power, the larger the etching selectivity of the PZT film relative to the platinum film, and the same conclusion can be obtained even when comparing the etching selectivity under the third condition and the fifth condition.
이상의 결과들을 정리하면, 비록 각 조건의 변화에 따라 얻어진 최대 식각 선택비는 1.13으로서 만족한 결과를 얻을 수는 없었으나 챔버내의 압력이 낮을수록, KHz 파워가 높을수록 식각 선택비가 향상된다는 경향성을 파악할 수 있었다.Summarizing the above results, although the maximum etching selectivity obtained according to the change of each condition could not be satisfactorily obtained, it was found that the lower the pressure in the chamber and the higher the KHz power, the better the etching selectivity. Could.
제2 실험예Experimental Example 2
전체 주입 가스량의 변화가 식각 선택비에 미치는 영향을 알아보기 위해 아르곤 가스를 10sccm로, 챔버내의 압력을 5mTorr로, KHz 파워를 250W로, MHz 파워를 500W로 고정시킨 후에 전체 주입 가스량을 변화시켰다.To determine the effect of the change in the total injection gas amount on the etching selectivity, the total injection gas amount was changed after fixing argon gas at 10 sccm, pressure in the chamber at 5 mTorr, KHz power at 250 W, and MHz power at 500 W.
도2 는 전체 주입 가스량을 20sccm으로 설정한 경우와 40sccm으로 설정한 경우에 식각 선택비의 변화를 나타내는 그래프이다. 도 2를 참조하면, 전체 가스 주입량이 20sccm에서 40sccm으로 2배 만큼 늘어났음에도 불구하고 식각 선택비는 거의 변화가 없음을 알 수 있다.Fig. 2 is a graph showing the change in the etching selectivity when the total injection gas amount is set to 20 sccm and when it is set to 40 sccm. Referring to FIG. 2, even though the total gas injection amount is increased by 2 times from 20 sccm to 40 sccm, the etching selectivity is almost unchanged.
제3 실험예Experimental Example 3
제1 및 제2 실험예에서는 CF4와 HBr의 혼합 가스 및 일정량의 아르곤(Ar) 가스가 포함된 식각 가스를 사용한 반면, 제3 실시예에서는 상기의 식각 가스에 CHF3가스를 더 첨가하여 상기 제1 및 제2 시료에 대한 식각 공정을 실시하고 그에 따른 식각 선택비의 변화를 관찰하였다.In the first and second experimental examples, an etching gas containing a mixed gas of CF 4 and HBr and a certain amount of argon (Ar) gas was used, whereas in the third embodiment, CHF 3 gas was further added to the etching gas. An etching process was performed on the first and second samples and the change in the etching selectivity was observed.
도 3은 KHz 파워와 MHz 파워를 각각 100W와 500W로 고정하고 HBr가스와 Ar가스의 주입량을 각각 10sccm로 하고 CF4가스의 주입량을 10sccm로 하는 식각 챔버내에 CHF3가스를 각각 0, 10, 30, 또는 50sccm 만큼 첨가한 경우에 Pt에 대한 PZT의 식각 선택비를 나타낸다.FIG. 3 shows that CHF 3 gas is 0, 10, 30 in an etching chamber in which KHz power and MHz power are fixed at 100W and 500W, respectively, and the injection amounts of HBr gas and Ar gas are 10sccm and the injection amount of CF 4 gas is 10sccm, respectively. Or, when added by 50 sccm, the etching selectivity ratio of PZT to Pt.
도 3으로부터, CHF3가스의 첨가량이 증가할수록 Pt에 대한 PZT의 식각 선택비도 증가함을 알 수 있다. 또한 CHF3가스의 첨가량이 50sccm인 경우에는 식각 선택비가 2.25로서 상당히 만족스러운 결과를 얻을 수 있었다. 이때, 상기 강유전막의 식각 가스중에 포함된 CHF3가스는 전체 가스의 30∼60%임이 바람직하다. 또, 상기 반응성 이온 식각은 KHz파워가 50∼500W이고, MHz파워가 50∼1200W이며, 반응 챔버내의 전체 압력이 1∼10mTorr인 것이 바람직하다.3, it can be seen that as the amount of CHF 3 gas added increases, the etching selectivity ratio of PZT to Pt also increases. In addition, when the addition amount of CHF 3 gas is 50sccm, the etching selectivity was 2.25, which was quite satisfactory. At this time, the CHF 3 gas contained in the etching gas of the ferroelectric film is preferably 30 to 60% of the total gas. The reactive ion etching preferably has a KHz power of 50 to 500 W, an MHz power of 50 to 1200 W, and an overall pressure in the reaction chamber of 1 to 10 mTorr.
상기의 실시예들로부터 CF4와 HBr가스에 첨가된 CHF3가스는 Pt에 대한 PZT의 식각 선택비를 높이는데 큰 영향을 미침을 알 수 있었다. 또한, 식각 선택비는 식각 챔버내의 압력이 낮을수록, KHz 파워가 높을수록 보다 높아짐을 알 수 있다.From the above examples, it can be seen that the CHF 3 gas added to CF 4 and HBr gas has a great effect on increasing the etching selectivity of PZT to Pt. In addition, it can be seen that the etching selectivity is higher the lower the pressure in the etching chamber, the higher the KHz power.
따라서, CHF3을 포함하는 식각 가스를 사용하여 강유전막을 식각하면, 강유전막의 하부에 존재하는 백금족 금속 박막과 산화막의 손상을 막을 수 있으므로 신뢰성 높은 반도체 소자를 제조할 수 있다.Therefore, when the ferroelectric film is etched by using an etching gas containing CHF 3 , damage to the platinum group metal thin film and the oxide film under the ferroelectric film can be prevented, thereby making it possible to manufacture highly reliable semiconductor devices.
한편, 본 발명은 상기 실시예에 한정되지 않으며, 본 발명의 기술적 사상의 범위 내에서 당업자에 의해 다양하게 변형될 수 있다.On the other hand, the present invention is not limited to the above embodiment, it can be variously modified by those skilled in the art within the scope of the technical idea of the present invention.
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