WO2004008520A1 - Method for structuring metal by means of a carbon mask - Google Patents

Method for structuring metal by means of a carbon mask Download PDF

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Publication number
WO2004008520A1
WO2004008520A1 PCT/DE2003/002125 DE0302125W WO2004008520A1 WO 2004008520 A1 WO2004008520 A1 WO 2004008520A1 DE 0302125 W DE0302125 W DE 0302125W WO 2004008520 A1 WO2004008520 A1 WO 2004008520A1
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layer
metal
etching
carbon
resist
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PCT/DE2003/002125
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German (de)
French (fr)
Inventor
Jens Bachmann
Lothar Brencher
Hans-Peter Sperlich
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Infineon Technologies Ag
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Priority to EP03763579A priority Critical patent/EP1522094A1/en
Publication of WO2004008520A1 publication Critical patent/WO2004008520A1/en
Priority to US11/030,587 priority patent/US20050181604A1/en

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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
    • H01L21/02—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
    • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
    • H01L21/321—After treatment
    • H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
    • H01L21/32139—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer using masks

Definitions

  • the invention relates to a method for metal structuring, in which at least one corrosion-intensive metal layer is deposited on a Si substrate by means of a deposition method, on which an etching mask is subsequently produced by means of a photolithographic structuring method using a resist and then by the etching mask by means of etching, preferably by plasma etching, the metal layer is structured.
  • Resist masks of this type define the structures for the etching process, for example the spatial limitation of metal structures.
  • a resist layer is first applied to the substrate and the resist mask is then structured using conventional photolithographic structuring methods (for example DUV, i-line, ).
  • a w / resist mask is used which is suitable for aser direct writing systems or for electron beam lithography.
  • the resist masks described can then in turn be used to structure the functional layer located under the resist mask.
  • Functional layers of this type which have been applied to a substrate in preparatory process steps, can be doped or undoped PolySi layers, Sio2 layers, metal layers and other required functional layers.
  • an erosion of the etching mask cannot be prevented due to a lack of sufficient selectivity.
  • a metal etching e.g. Executed in an Al or AlCu layer
  • sufficient passivation of the already etched structures must be ensured at the same time during the etching process.
  • a side wall passivation can be achieved in the already etched metal structures due to the by-products, in particular carbon compounds, which arise during the etching process.
  • This passivation is based on the resist as a carbon source and is supported by additives in the etching gas atmosphere, such as N2, CHF3, CH4.
  • the passivation is necessary in order to protect the already etched Al structures from further undesired corrosion by the etching media during the etching process, which proceeds further into the depth of the metal layer.
  • the maximum height of the metal layer, which has to be completely etched through, is strictly limited by the thickness of the resist mask.
  • this resist mask is also etched or eroded during the etching process, so that the depth of the metal etching is mainly determined by the thickness of the resist mask.
  • the thickness of the resist mask is limited by other facts, such as the process window for the lithography and the stability.
  • Such hard masks exist for for example made of SiO, SiON, W, TiN, or combinations of these materials.
  • the hard masks have a significantly higher selectivity compared to the usual resist masks, as a result of which, compared to resist masks, significantly deeper etching trenches can be achieved in metal layers depending on further etching parameters.
  • the necessary side wall passivation can be better realized with resist masks, since these supply the required carbon during the etching process. It has also been shown that carbon-rich processes, e.g. due to the passivating effect, are particularly advantageous with regard to the defect density.
  • hard masks cannot supply the carbon required for the side wall passivation.
  • this became particularly critical in connection with sputtered Al layers in that an increase in corrosion damage occurred.
  • the carbon required for the sidewall passivation in Al etching cannot be extracted by gases, e.g. CH4, feed, at least oppose the technological barriers.
  • a method for etching structures has become known from US Pat. No. 5,981,398-A, in which a hard mask is first produced by means of a photoresist and the known photolithographic methods, which are then used for structuring a blanket target layer is used.
  • the hard mask In order to be able to carry out the etching process with a plasma containing chlorine, the hard mask consists of materials which consist of the group of SOG materials (silesquioxane spin-on-glass) and amorphous carbon materials.
  • This hard mask layer is first on the layer to be structured, which can be a metal layer, by chemical vapor deposition (CVD), physical vapor deposition (PVD) or also HDP-CVD (high density plasma chemical vapor deposition) deposited and then a resist layer on this.
  • An ARC layer (anti-reflection layer) or a buffer layer will also be arranged between the metal layer and the hard mask layer.
  • the ARC layer can be a dielectric Sio2 layer.
  • the photoresist is subsequently structured into a first mask using one of the known photolithographic methods.
  • the hard mask can then be structured with a fluorine-containing first plasma, so that a second etching mask is formed.
  • the subsequent structuring of the metal layer is then carried out with a chlorine-containing plasma with high selectivity to the hard mask, so that even thicker metal layers (target layer) can be etched with the comparatively complex process.
  • the thickness of the hard mask can be significantly less than the thickness of the target layer.
  • the disadvantage here is that several etching steps with different etching parameters have to be carried out.
  • the amorphous carbon-containing hard mask layer which has been deposited by the HDP-CVD process, serves simultaneously as a carbon source and for the realization of an oxygen-containing etching plasma.
  • the invention is based on the object of creating a simplified method for metal structuring, in particular for structuring AL-containing metal layers, with which sufficient passivation of the etched metal structures is ensured by simple means during the etching process.
  • the object on which the invention is based is achieved in a method of the type mentioned at the outset in that a hard layer in the form of a carbon layer and on which the resist is deposited, that after the structuring of the resist layer, the carbon layer is structured by stripping to form a carbon mask, that the metal etching is then carried out with simultaneous sidewall passivation with the carbon mask defining the structures, and that the masks are then stripped.
  • SiCH silicon carbide
  • SiOC silicon oxycarbide
  • a w / cap layer can also be deposited between the carbon layer and the resist.
  • the hard mask according to the invention now fulfills several functions by first defining the structures to be etched and at the same time providing a rich carbon source for the sidewall passivation of the etched metal structures. A suitable protection by the side wall passivation is compared to the otherwise commonly used hard masks, such as SiO, SiON ... achieved so that the well-known AL corrosion problems are avoided.
  • a significant simplification of the metal structuring is also achieved in that the additional etching stop layer, e.g. a dielectric ARC layer can be omitted if the hard mask is made of SiCH, since this layer is sufficiently oxygen-resistant.
  • the additional etching stop layer e.g. a dielectric ARC layer can be omitted if the hard mask is made of SiCH, since this layer is sufficiently oxygen-resistant.
  • a stack built up on a Si substrate consisting of a carbon hard mask and a w / cap layer located thereon and one on top this resist located;
  • AlCu metal layer 2 has been deposited on the Si substrate 1 by means of a conventional CVD method.
  • This metal layer 2 consists of a stack of a thin layer Ti (around 50 nm), an AlCu layer around 1000 nm, on which there is a thin TiN layer (around 40 nm).
  • the metal layer 2 can also consist of a stack of a very thin layer Ti (around 10 nm), a thicker layer AlCu (around 400 nm), another very thin Ti layer (around 5 nm) and a TiN layer (around 40 nm) exist.
  • a carbon layer 3 with a thickness of around 200 to 500 nm, on which in turn a w / cap layer 4 (SiON) and a resist 5 above.
  • the w / cap layer 4 serves as a stop layer in lithography.
  • FIG. 2 shows the layer structure according to FIG. 1 after the resist 4 has been structured photolithographically, for example by means of DUV, i-line, .. Then the w / cap layer 4 and the underlying carbon layer 3 can be etched in-situ, ie simultaneously. The result is the hard mask shown in FIG. 3, which is used directly for structuring the metal layer 2 by metal etching.
  • the etching trench 6 extends into the substrate 1. On the passivated side walls of the metal layer 2.
  • etching residues 7 present in the etching trenches can e.g. can be removed by wet chemistry (FIGS. 4, 5).

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
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Abstract

The invention relates to a method for structuring metal, in which at least one metal layer (2), e.g. made of aluminum, is deposited on an Si substrate (1) by means of a deposition method, whereupon an etching mask is produced on said metal layer (2) that is subsequently structured by means of etching, preferably plasma etching. The aim of the invention is to create a simplified method for structuring metal, which ensures sufficient passivation of the etched metal structures during the etching process by using simple means. Said aim is achieved by the fact that a hard mask layer is deposited on the previously deposited metal layer (2) that is to be structured, said hard mask layer being in the form of a carbon layer (3) on which a resist (5) is deposited. The carbon layer is structured by stripping once the resist has been structured so as to form a carbon mask. The metal layer is then etched with the carbon mask defining the structures thereof while passivating the side walls, whereupon the masks are stripped.

Description

Verfahren zur Metallstrukturierung Process for metal structuring
Die Erfindung betrifft ein Verfahren zur Metallstrukturierung, bei dem auf einem Si-Substrat mittels Abscheide-Verfahren wenigstens eine korrosionsintensive Metallschicht abgeschieden wird, auf der nachfolgend eine Ätzmaske durch fotolithografi- sche Strukturierungsverfahren unter Verwendung eines Resists erzeugt wird und anschließend durch die Ätzmaske mittels Ätzen, vorzugsweise durch Plasmaätzen, die Metallschicht strukturiert wird.The invention relates to a method for metal structuring, in which at least one corrosion-intensive metal layer is deposited on a Si substrate by means of a deposition method, on which an etching mask is subsequently produced by means of a photolithographic structuring method using a resist and then by the etching mask by means of etching, preferably by plasma etching, the metal layer is structured.
Die klassische Metallätzung in der Halbleiterindustrie erfor- dert die Verwendung einer geeigneten Resist-Maske. Derartige Resist-Masken definieren die Strukturen für den Ätzvorgang, z.B. die räumliche Begrenzung von Metallstrukturen. Zu diesem Zweck wird zunächst eine Resist-Schicht auf dem Substrat aufgebracht und die Resist-Maske danach mit üblichen fotolithografi- sehen Strukturierungsverfahren (z.B. DUV, i-line, ... ) strukturiert. Zu Realisierung besonders geringer Strukturbreiten wird eine w/-Resist Maske verwendet, die für aser-Direkt- Schreibsysteme oder die Elektronenstrahlen-Lithographie geeignet sind. Die beschriebenen Resist-Masken können dann ihrer- seits zur Strukturierung der unter der Resist-Maske befindlichen Funktionsschicht eingesetzt werden. Derartige Funktionsschichten, die in vorbereitenden Prozessschritten auf ein Substrat aufgebracht worden sind, können dotierte oder undotierte PolySi-Schichten, Sio2-Schichten, Metallschichten sowie weitere erforderliche Funktionsschichten sein. Während des Ätzvorganges, der beispielsweise durch Plasmaätzen in einer geeigneten Atmosphäre ausgeführt wird, ist allerdings mangels einer ausreichenden Selektivität eine Erosion der Ätz- maske nicht zu verhindern.The classic metal etching in the semiconductor industry requires the use of a suitable resist mask. Resist masks of this type define the structures for the etching process, for example the spatial limitation of metal structures. For this purpose, a resist layer is first applied to the substrate and the resist mask is then structured using conventional photolithographic structuring methods (for example DUV, i-line, ...). To achieve particularly small structure widths, a w / resist mask is used which is suitable for aser direct writing systems or for electron beam lithography. The resist masks described can then in turn be used to structure the functional layer located under the resist mask. Functional layers of this type, which have been applied to a substrate in preparatory process steps, can be doped or undoped PolySi layers, Sio2 layers, metal layers and other required functional layers. During the etching process, which is carried out, for example, by plasma etching in a suitable atmosphere, an erosion of the etching mask cannot be prevented due to a lack of sufficient selectivity.
Wird eine Metallätzung z.B. in einer AI- oder AlCu-Schicht ausgeführt, muss während des Ätzvorganges gleichzeitig für eine ausreichende Passivierung der bereits geätzten Strukturen ge- sorgt werden. Durch die während des Ätzvorganges entstehenden Nebenprodukte, insbesondere Kohlenstoffverbindungen, kann eine Seitenwandpassivierung in den bereits geätzten Metallstrukturen erreicht werden. Diese Passivierung basiert auf dem Resist als Kohlenstoffquelle und wird durch Zusätze in der Ätzgasatmosphä- re, wie N2, CHF3 , CH4 unterstützt.If a metal etching e.g. Executed in an Al or AlCu layer, sufficient passivation of the already etched structures must be ensured at the same time during the etching process. A side wall passivation can be achieved in the already etched metal structures due to the by-products, in particular carbon compounds, which arise during the etching process. This passivation is based on the resist as a carbon source and is supported by additives in the etching gas atmosphere, such as N2, CHF3, CH4.
Die Passivierung ist notwendig, um die bereits geätzten AI- Strukturen vor einer weiteren unerwünschten Korrosion durch die Ätzmedien während des weiter in die Tiefe der Metallschicht fortschreitenden Ätzvorganges zu schützen.The passivation is necessary in order to protect the already etched Al structures from further undesired corrosion by the etching media during the etching process, which proceeds further into the depth of the metal layer.
Wegen der geringen Selektivität des Ätzvorganges gegenüber dem Metall wird die maximale Höhe der Metallschicht, die vollständig durchgeätzt werden muss, durch die Dicke der Resist-Maske streng begrenzt.Because of the low selectivity of the etching process with respect to the metal, the maximum height of the metal layer, which has to be completely etched through, is strictly limited by the thickness of the resist mask.
Diese Resist-Maske wird, wie bereits ausgeführt, während des Ätzvorganges ebenfalls abgeätzt bzw. erodiert, so dass die Tiefe der Metallätzung hauptsächlich durch die Dicke der Resist- Maske bestimmt wird. Die Dicke der Resist-Maske wiederum wird durch andere Fakten, wie das Prozessfenster für die Lithographie und die Stabilität, begrenzt.As already stated, this resist mask is also etched or eroded during the etching process, so that the depth of the metal etching is mainly determined by the thickness of the resist mask. The thickness of the resist mask, in turn, is limited by other facts, such as the process window for the lithography and the stability.
Diese Probleme haben zur Entwicklung und die praktische Nutzung von Hard-Masken zur Definition der Strukturen beim AL- tzen geführt. Solche gegenwärtig genutzten Hard-Masken bestehen bei- spielsweise aus SiO, SiON, W, TiN, oder Kombinationen dieser Materialien.These problems have led to the development and practical use of hard masks to define the structures in ALtzen. Such hard masks currently used exist for for example made of SiO, SiON, W, TiN, or combinations of these materials.
Die Hard-Masken besitzen einerseits gegenüber den üblichen Re- sist-Masken eine deutlich höhere Selektivität, wodurch gegenüber Resist-Masken deutlich tiefere Ätzgräben in Metallschichten in Abhängigkeit von weiteren Ätzparametern erreicht werden können. Andererseits lässt sich die notwendige Seitenwandpassi- vierung mit Resist-Masken besser realisieren, da diese während des Ätzvorganges den benötigten Kohlenstoff liefern. Es hat sich auch gezeigt, dass kohlenstoffreiche Prozesse, z.B. bedingt durch die passivierende Wirkung, besonders vorteilhaft in Bezug auf die Defektdichte sind.On the one hand, the hard masks have a significantly higher selectivity compared to the usual resist masks, as a result of which, compared to resist masks, significantly deeper etching trenches can be achieved in metal layers depending on further etching parameters. On the other hand, the necessary side wall passivation can be better realized with resist masks, since these supply the required carbon during the etching process. It has also been shown that carbon-rich processes, e.g. due to the passivating effect, are particularly advantageous with regard to the defect density.
Der besondere Nachteil der Hard-Masken ist darin zu sehen, dass diese den für die Seitenwandpassivierung benötigten Kohlenstoff nicht liefern können. Insbesondere wurde das in Verbindung mit gesputterten AI-Schichten besonders kritisch, indem eine Häufung von Korrosionsschäden auftrat. Auch lässt sich der für die Seitenwandpassivierung beim Al-Ätzen benötigte Kohlenstoff nicht durch Gase, z.B. CH4, zuführen, jedenfalls stehen dem technologische Schranken entgegen.The particular disadvantage of hard masks is that they cannot supply the carbon required for the side wall passivation. In particular, this became particularly critical in connection with sputtered Al layers in that an increase in corrosion damage occurred. Also, the carbon required for the sidewall passivation in Al etching cannot be extracted by gases, e.g. CH4, feed, at least oppose the technological barriers.
Aus der US-5 981 398-A ist ein Verfahren zum Ätzen von Struktu- ren bekannt geworden, bei dem zunächst eine Hard-Maske mittels eines Fotoresists und der bekanten fotolithografischen Verfahren erzeugt wird, die dann zur Strukturierung einer Deckschicht (blanket target layer) verwendet wird.A method for etching structures has become known from US Pat. No. 5,981,398-A, in which a hard mask is first produced by means of a photoresist and the known photolithographic methods, which are then used for structuring a blanket target layer is used.
Um den Ätzvorgang mit einem Chlor enthaltenden Plasma durchführen zu können, besteht die Hard-Maske aus Materialien, die aus der Gruppe der SOG-Materialien (silesquioxane spin-on-glas) und amorphen Kohlenstoffmaterialien bestehen. Diese Hard-Masken- Schicht wird zunächst auf der zu strukturierenden Schicht, die eine Metallschicht sein kann, durch chemische Dampfphasen- Abscheidung (CVD) , physikalische Dampfabscheidung (PVD) oder auch HDP-CVD (high density plasma chemical vapor deposition) abgeschieden und auf dieser dann anschließend eine Re- sistschicht. Zwischen der Metallschicht und der Hard-Masken- Schicht wird zusätzlich eine ARC-Schicht (Antireflexions- schicht) oder eine Pufferschicht angeordnet werden. Die ARC- Schicht kann eine dielektrische Sio2-Schicht sein.In order to be able to carry out the etching process with a plasma containing chlorine, the hard mask consists of materials which consist of the group of SOG materials (silesquioxane spin-on-glass) and amorphous carbon materials. This hard mask layer is first on the layer to be structured, which can be a metal layer, by chemical vapor deposition (CVD), physical vapor deposition (PVD) or also HDP-CVD (high density plasma chemical vapor deposition) deposited and then a resist layer on this. An ARC layer (anti-reflection layer) or a buffer layer will also be arranged between the metal layer and the hard mask layer. The ARC layer can be a dielectric Sio2 layer.
Der Fotoresist wird nachfolgend mit einem der bekannten fotolithographischen Verfahren zu einer ersten Maske strukturiert. Mit einem Fluor enthaltenden ersten Plasma kann danach die Hard-Maske strukturiert werden, so dass eine zweite Ätzmaske ausgebildet wird. Die nachfolgenden Strukturierung der Metallschicht wird dann mit einem Chlor enthaltenden Plasma mit hoher Selektivität zur Hard-Maske ausgeführt, so dass mit dem ver- gleichsweise aufwändigen Verfahren auch dickere Metallschichten (target layer) geätzt werden können. Die Dicke der Hard-Maske kann dabei deutlich unter der Dicke der Target-Layer liegen. Nachteilig hierbei ist allerdings, dass mehrere Ätzschritte mit unterschiedlichen Ätzparametern ausgeführt werden müssen.The photoresist is subsequently structured into a first mask using one of the known photolithographic methods. The hard mask can then be structured with a fluorine-containing first plasma, so that a second etching mask is formed. The subsequent structuring of the metal layer is then carried out with a chlorine-containing plasma with high selectivity to the hard mask, so that even thicker metal layers (target layer) can be etched with the comparatively complex process. The thickness of the hard mask can be significantly less than the thickness of the target layer. The disadvantage here, however, is that several etching steps with different etching parameters have to be carried out.
Die amorphen Kohlenstoff enthaltende Hard-Mask-Schicht, welche durch das HDP-CVD-Verfahren abgeschieden worden ist, dient gleichzeitig als Kohlenstoffquelle und zur Realisierung eines sauerstoffhaltigen Ätzplasmas.The amorphous carbon-containing hard mask layer, which has been deposited by the HDP-CVD process, serves simultaneously as a carbon source and for the realization of an oxygen-containing etching plasma.
Der Erfindung liegt nunmehr die Aufgabe zugrunde, ein vereinfachtes Verfahren zur Metallstrukturierung, insbesondere zur Strukturierung von AL-enthaltenden Metallschichten, zu schaffen, mit dem mit einfachen Mitteln während des Ätzprozesses ei- ne ausreichende Passivierung der geätzten Metallstrukturen sichergestellt wird.The invention is based on the object of creating a simplified method for metal structuring, in particular for structuring AL-containing metal layers, with which sufficient passivation of the etched metal structures is ensured by simple means during the etching process.
Die der Erfindung zugrundeliegende Aufgabe wird bei einem verfahren der eingangs genannten Art dadurch gelöst, dass auf der bereits abgeschiedenen und strukturierenden Metallschicht zunächst eine Hard-Schicht in Form einer Kohlenstoffschicht und auf dieser der Resist abgeschieden wird, dass nach der Strukturierung der Resistschicht die Kohlenstoffschicht durch Strippen zu einer Kohlenstoffmaske strukturiert, dass danach mit der die Strukturen definierenden Kohlenstoffmaske die Metallätzung bei gleichzeitigen Seitenwandpassivierung ausgeführt wird und dass anschließend die Masken gestrippt werden.The object on which the invention is based is achieved in a method of the type mentioned at the outset in that a hard layer in the form of a carbon layer and on which the resist is deposited, that after the structuring of the resist layer, the carbon layer is structured by stripping to form a carbon mask, that the metal etching is then carried out with simultaneous sidewall passivation with the carbon mask defining the structures, and that the masks are then stripped.
Für die KohlenstoffSchicht wird reiner Kohlenstoff bevorzugt, wobei auch Siliziumcarbid (SiCH) oder Silizium Oxycarbid (SiOC) verwendet werden, wobei SiCH verwendet werden kann.Pure carbon is preferred for the carbon layer, silicon carbide (SiCH) or silicon oxycarbide (SiOC) also being used, it being possible for SiCH to be used.
Zwischen der Kohlenstoffschicht und dem Resist kann zusätzlich eine w/ cap-Schicht abgeschieden werden.A w / cap layer can also be deposited between the carbon layer and the resist.
Die besonderen Vorteile der Erfindung sind darin zu sehen, dass die Hard-Maske erfindungsgemäß nunmehr mehrere Funktionen erfüllt, indem zunächst die zu ätzenden Strukturen definiert werden und gleichzeitig eine ergiebige Kohlenstoffquelle für die Seitenwandpassivierung der geätzten Metallstrukturen bereitge- stellt wird. Ein geeigneter Schutz durch die Seitenwandpassivierung wird gegenüber den sonst üblicherweise verwendeten Hard-Masken, wie z.B. SiO, SiON ... erreicht, so dass die bekannten AL-Korrosionsprobleme vermieden werden.The particular advantages of the invention can be seen in the fact that the hard mask according to the invention now fulfills several functions by first defining the structures to be etched and at the same time providing a rich carbon source for the sidewall passivation of the etched metal structures. A suitable protection by the side wall passivation is compared to the otherwise commonly used hard masks, such as SiO, SiON ... achieved so that the well-known AL corrosion problems are avoided.
Eine deutliche Vereinfachung der Metallstrukturierung wird weiterhin auch dadurch erreicht, dass die sonst zusätzlich erforderliche Ätzstopp-Schicht, z.B. eine dielektrische ARC-Schicht, entfallen kann, wenn die Hard-Maske aus SiCH besteht, da diese Schicht ausreichend Sauerstoffresistent ist.A significant simplification of the metal structuring is also achieved in that the additional etching stop layer, e.g. a dielectric ARC layer can be omitted if the hard mask is made of SiCH, since this layer is sufficiently oxygen-resistant.
Die Erfindung soll nachfolgend an einem Ausführungsbeispiel näher erläutert werden. In den zugehörigen Zeichnungen zeigen:The invention will be explained in more detail using an exemplary embodiment. In the accompanying drawings:
Fig. 1: einen auf einem Si-Substrat aufgebauten Stapel, be- stehend aus einer Kohlenstoff-Hard-Maske und einer darüber befindlichen w/ cap Schicht und einem auf dieser befindlichen Resist;1: a stack built up on a Si substrate, consisting of a carbon hard mask and a w / cap layer located thereon and one on top this resist located;
Fig. 2: den Stapel nach der Lithographie mit dem strukturierten Resist;2: the stack after the lithography with the structured resist;
Fig. 3: den Stapel nach der Öffnung der Hard-Maske und der w/ cap Schicht;3: the stack after opening the hard mask and the w / cap layer;
Fig. 4: den Stapel nach der Metallätzung mit einem rest der Hard-Maske und eine Polymerschicht in den Ätzgräben;4: the stack after the metal etching with a rest of the hard mask and a polymer layer in the etching trenches;
Fig. 5: den Stapel nach dem Strippen der Hard-Maske; und5: the stack after stripping the hard mask; and
Fig. 6 den Stapel mit strukturierter Metallschicht nach der Entfernung des Polymers.6 shows the stack with a structured metal layer after the removal of the polymer.
In Fig. 1 ist ein zu strukturierender Schichtaufbau auf einem Si-Substrat 1 schematisch dargestellt. Auf dem Si-Substrat 1 ist eine AlCu-Metallschicht 2 mittels eines üblichen CVD- Verfahrens abgeschieden worden. Diese Metallschicht 2 besteht aus einem Stack aus einer dünnen Schicht Ti (um 50 nm) , einer um 1000 nm dicken AlCu Schicht, auf der sich eine dünne TiN- Schicht (um 40 nm) befindet. Alternativ kann die Metallschicht 2 auch aus einem Stack aus einen sehr dünnen Schicht Ti (um 10 nm) , einer dickeren Schicht AlCu (um 400 nm) , eine weiteren sehr dünnen Ti-Schicht (um 5 nm) und einer TiN-Schicht (um 40 nm) bestehen.1 schematically shows a layer structure to be structured on an Si substrate 1. An AlCu metal layer 2 has been deposited on the Si substrate 1 by means of a conventional CVD method. This metal layer 2 consists of a stack of a thin layer Ti (around 50 nm), an AlCu layer around 1000 nm, on which there is a thin TiN layer (around 40 nm). Alternatively, the metal layer 2 can also consist of a stack of a very thin layer Ti (around 10 nm), a thicker layer AlCu (around 400 nm), another very thin Ti layer (around 5 nm) and a TiN layer (around 40 nm) exist.
Auf dieser Metallschicht 2 befindet sich eine Kohlenstoff- schicht 3 mit einer Dicke um 200 ... 500 nm, auf der wiederum eine w/ cap Schicht 4 (SiON) und darüber ein Resist 5. Die w/ cap - Schicht 4 dient als Stoppschicht bei der Lithographie.On this metal layer 2 there is a carbon layer 3 with a thickness of around 200 to 500 nm, on which in turn a w / cap layer 4 (SiON) and a resist 5 above. The w / cap layer 4 serves as a stop layer in lithography.
Fig. 2 zeigt den Schichtaufbau nach Fig. 1 nachdem der Resist 4 fotolithographisch, z.B. mittels DUV, i-line,.., strukturiert worden ist. Anschließend kann die w/ cap - Schicht 4 und die darunter liegende KohlenstoffSchicht 3 in-situ, d.h. gleichzeitig, geätzt werden. Das Ergebnis ist die in Fig. 3 dargestellte Hard-Maske, die unmittelbar zur Strukturierung der Metallschicht 2 durch Metallätzen.FIG. 2 shows the layer structure according to FIG. 1 after the resist 4 has been structured photolithographically, for example by means of DUV, i-line, .. Then the w / cap layer 4 and the underlying carbon layer 3 can be etched in-situ, ie simultaneously. The result is the hard mask shown in FIG. 3, which is used directly for structuring the metal layer 2 by metal etching.
In Fig. 4 ist der Schichtaufbau nach der Metallätzung dargestellt, wobei die Metallschicht 2 vollkommen durchgeätzt worden ist. Der Ätzgraben 6 reicht bis in das Substrat 1. Auf den pas- sivierten Seitenwänden der Metallschicht 2.4 shows the layer structure after the metal etching, the metal layer 2 having been completely etched through. The etching trench 6 extends into the substrate 1. On the passivated side walls of the metal layer 2.
Nachfolgend wird der Rest der Kohlenstoffschicht 3 in-situ gestrippt. Eventuell vorhandene Ätzrückstände 7 in den Ätzgräben können z.B. nasschemisch entfernt werden (Fig. 4, 5).The rest of the carbon layer 3 is subsequently stripped in situ. Any etching residues 7 present in the etching trenches can e.g. can be removed by wet chemistry (FIGS. 4, 5).
Die nach dem erfindungsgemäßen Verfahren fertiggestellte Metallstruktur zeigt schließlich Fig. 6. Finally, the metal structure produced by the method according to the invention is shown in FIG. 6.
Verfahren zur MetallstrukturierungProcess for metal structuring
BezugszeichenlisteLIST OF REFERENCE NUMBERS
Substratsubstratum
AlCu-MetallschichtAlCu metal layer
Kohlenstoff w/ cap layerCarbon w / cap layer
Resistresist
Ätzgrabenetched trench
Ätzrückstände etch residues

Claims

Verfahren zur MetallstrukturierungPatentansprüche Process for metal structuringPatent claims
1. Verfahren zur Metallstrukturierung, bei dem auf einem Si- Substrat mittels Abscheide-Verfahren wenigstens eine korrosionsintensive Metallschicht abgeschieden wird, auf der nachfolgend eine Ätzmaske durch fotolithografische Strukturierungsverfahren unter Verwendung eines Resists erzeugt wird und an- schließend durch die Ätzmaske mittels Ätzen, vorzugsweise durch Plasmaätzen, die Metallschicht strukturiert wird, d a du r c h g e k e n n z e i c h n e t, dass auf der bereits abgeschiedenen und zu strukturierenden Metallschicht (2) zunächst eine Hard-Schicht in Form einer KohlenstoffSchicht (3) und auf die- ser der Resist (5) abgeschieden wird, dass nach der Strukturierung des Resists (5) die KohlenstoffSchicht (3) durch Strippen zu einer Kohlenstoffmaske strukturiert, dass danach mit der die Strukturen definierenden Kohlenstoffmaske die Metallätzung der Metallschicht (2) bei gleichzeitiger Seitenwandpassivierung ausgeführt wird und dass anschließend die Masken gestrippt werden.1. A method for metal structuring, in which at least one corrosion-intensive metal layer is deposited on a Si substrate by means of a deposition method, on which an etching mask is subsequently produced by means of a photolithographic structuring method using a resist and then by means of the etching mask by means of etching, preferably by Plasma etching, the metal layer is structured, since you are characterized in that a hard layer in the form of a carbon layer (3) is first deposited on the metal layer (2) that has already been deposited and is to be structured, and the resist (5) is then deposited on this the structuring of the resist (5) structures the carbon layer (3) by stripping to form a carbon mask, that the metal etching of the metal layer (2) is carried out with the carbon mask defining the structures with simultaneous sidewall passivation and that the masks are then stripped ,
2. Verfahren nach Anspruch 1, d a d u r c h g e k e n n - z e i c h n e t, dass die KohlenstoffSchicht (3) aus reinem Kohlenstoff besteht.2. The method according to claim 1, d a d u r c h g e k e n n - z e i c h n e t that the carbon layer (3) consists of pure carbon.
3. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, dass die KohlenstoffSchicht (3) aus Silizium- carbid (SiCH) hergestellt wird. 3. The method according to claim 1, characterized in that the carbon layer (3) is made of silicon carbide (SiCH).
4. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, dass die Kohlenstoffschicht (3) aus Silizium Oxycarbid (SiOC) hergestellt wird.4. The method according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the carbon layer (3) is made of silicon oxycarbide (SiOC).
5. Verfahren nach einem der Ansprüche 1 bis 4, d a d u r c h g e k e n n z e i c h n e t, dass zwischen der Kohlenstoff- schicht (3) und dem Resist (5) eine w/ cap-Schicht (4) abgeschieden wird. 5. The method according to any one of claims 1 to 4, that a w / cap layer (4) is deposited between the carbon layer (3) and the resist (5).
PCT/DE2003/002125 2002-07-11 2003-06-26 Method for structuring metal by means of a carbon mask WO2004008520A1 (en)

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