Method for forming openings in low dielectric constant material layer
The invention is directed towards a method for forming openings in low-k dielectric layers and a structure for forming an opening thereof. A mask layer comprising at least one metal hard mask layer and one or more hard mask layers is applied on the dielectric layer for forming the opening.
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This application is a continuation-in-part of prior applications Ser. No. 10/044,322, filed Jan. 10, 2002.
BACKGROUND OF THE INVENTION1. Field of Invention
The present invention relates to a method for manufacturing semiconductor devices. More particularly, the present invention relates to a method for forming openings in dielectric material layers.
2. Description of Related Art
In the semiconductor fabrication process, as the dimension of devices on a chip becomes smaller, the density of interconnect pitch becomes higher. Because widely used silicon oxide dielectric layers have high dielectric constants, it can easily result in high RC delay. Therefore, low dielectric constant (low-k) dielectric material is used instead as an inter-metal dielectric (IMD) in high speed ICs. To apply low k dielectric has the advantage such as reducing the interconnection parasitic capacitance, consequently reducing the RC delay, or mitigating the cross talk between metal lines, hence, the operation speed is improved. Hence, the low k dielectric material is a very popular IMD material used in high speed ICs.
The low k dielectric materials include inorganic materials, such as HSQ, FSG and CORAL, and organic materials, such as flare, SILK and parylene.
In the conventional via-first process for forming damascene opening, as shown in
After removing the first photoresist layer, a gap filling process is performed to fill the via with a polymer material layer to protect the cap nitride layer. After a patterned second photoresist layer is formed on the polymer material layer, a second anisotropic etching process is performed to define a trench, by using the stop layer as an etching stop layer.
However, the polymer material layer covering the via opening provokes a fence profile 110 around top of the opening 120, as shown in
Furthermore, while the second photoresist layer is subsequently stripped by a photoresist removal process, such as a nitrogen/oxygen plasma ashing process or a nitrogen/hydrogen plasma process, the performed photoresist removal process usually damages the side walls 107 of the second dielectric layer 108, leading to dielectric constant shift of the low-k dielectric layer. Moreover, the low-k dielectric material of the damaged sidewalls 107 tends to absorb moisture, resulting in degradation in the follow-up metallization process.
SUMMARY OF THE INVENTIONIt is therefore an object of the invention to provide a method for forming openings in the dielectric material layer. The disadvantage of photoresist striping by plasma is improved, and no fence profile is provoked. Therefore, it is more advantageous for the fabrication for forming openings in low-k material layers, especially the low-k material layers containing metal wires or interconnects.
To achieve these objects and advantages, and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention is directed towards a method for forming openings in a dielectric layer and a structure with an opening in the dielectric layer. A dielectric layer is formed over the provided substrate, and the dielectric layer can be a single layer or comprises stack dielectric layers of different dielectric materials. Preferably, the dielectric layer is a low-k dielectric layer. A mask layer comprising at least a metal hard mask layer and a hard mask layer and a first anti-reflection layer are formed on the dielectric layer. A stop layer can be further included in the mask layer. The usage of the metal hard mask layer and the hard mask layer is one of the advantageous features of the present invention. After patterning the mask layer, a second anti-reflection layer is formed. Using a patterned second photoresist layer formed on the second anti-reflection layer as a mask, a via opening is defined. After removing the second photoresist layer along with the second anti-reflection layer, a damascene opening is formed by using the mask layer as a mask.
The resultant structure with a damascene opening at least comprising: the substrate, the dielectric layer with the damascene opening and the patterned mask layer that includes at least one metal hard mask layer and one or more hard mask layers on the dielectric layer. Before the mask layer is patterned, the structure for forming the opening further includes an anti-reflection layer on the mask layer.
By using the patterned mask layer comprising at least a metal hard mask layer as a mask along with the gap-filling anti-reflection layer, the dielectric layer is protected from plasma damage.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGSThe accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,
Referring to
Afterwards, a chemical mechanical polishing (CMP) stop layer 210, a metal hard mask layer 212, a hard mask layer 214 and a bottom anti-reflection coating (BARC) layer 216 are formed in sequence on the second dielectric layer 208. The CMP stop layer 210 is, for example, a silicon nitride layer or a silicon carbide layer with a thickness of about 400-700 Å, preferably 500 Å. Materials for forming the metal hard mask layer 212 includes tantalum, tantalum nitride, tungsten, tungsten nitride, titanium nitride and titanium, formed by, for example, CVD or sputtering. The metal hard mask layer 212 has a thickness of about 100-300 Å, preferably 200 Å. The hard mask layer 214 is, for example, a silicon nitride layer or a silicon carbide layer with a thickness of about 1000-2000 Å, preferably 1500 Å. The formation of the metal hard mask layer and the hard mask layer is one of the advantageous features of the present invention.
Afterwards, a patterned first photoresist layer 220 is formed on the BARC layer 216.
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Although sidewalls of the via opening 232 is exposed to plasma damage for stripping the photoresist, the damaged sidewalls of the via opening 232 is removed during the second anisotropic etching process.
Referring to
Afterwards, a conductive layer (not shown) is formed to fill the damascene opening 234. The material for forming the conductive layer includes aluminum, copper or other metals formed by sputtering or CVD. The conductive layer is then planarized by CMP using the CMP stop layer 210 as a polishing stop layer, so that a damascene interconnect 236 is formed within the opening 234, as shown in
The following processes are well known to persons skilled in the art, and will not be further described therein.
By using the patterned hard mask layer and the patterned metal hard mask layer as a mask along with the gap-filling BARC material layer, the low-k dielectric layers are protected from plasma damage for stripping the photoresist. Moreover, no gap filling process is required for the via opening, thus avoiding the fence profile.
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Afterwards, a patterned first photoresist layer 320 is formed on the ARC layer 314.
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The resultant structure with the damascene opening at least comprising: the substrate, the dielectric layer with the damascene opening and the patterned mask layer that includes at least one metal hard mask layer and one or more hard mask layers on the dielectric layer. Before the mask layer is patterned, the structure for forming the opening further includes an anti-reflection layer on the mask layer.
Referring to
However, the opening described herein is not limited to a damascene opening. Other types of openings, including via openings, trench openings and contact openings are within the scope of the present invention.
By using the patterned mask layer as a mask along with the gap-filling ARC material layer, the dielectric layer is protected from plasma damage.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Claims
1-27. (canceled)
28. A structure for forming an opening on a substrate, comprising:
- a first dielectric layer on the substrate;
- a second dielectric layer on the dielectric layer;
- a plurality of mask layers at least comprising a metal mask layer on the second dielectric layer; and
- an anti-reflection layer on the plurality of mask layers.
29. The structure as claimed in claim 28, wherein materials for forming the first and second dielectric layers include inorganic polymer containing silicon.
30. The structure as claimed in claim 28, wherein the anti-reflection layer is a bottom anti-reflection coating layer made of fluid organic polymer.
31. The structure as claimed in claim 28, wherein the metal mask layer is made of one of the following materials selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
32. The structure as claimed in claim 28, wherein the mask layer is a silicon nitride layer or a silicon carbide layer.
33. A structure for forming an opening on a substrate, comprising:
- a first dielectric layer on the substrate;
- a first stop layer on the first dielectric layer;
- a second dielectric layer on the first stop layer;
- a third dielectric layer on the second dielectric layer;
- a plurality of mask layers at least comprising a metal mask layer on the third dielectric layer; and
- an anti-reflection layer on the plurality of mask layers.
34. The structure as claimed in claim 33, wherein materials for forming the first and second dielectric layers include inorganic polymer containing silicon.
35. The structure as claimed in claim 33, wherein the anti-reflection layer is a bottom anti-reflection coating layer made of fluid organic polymer.
36. The structure as claimed in claim 33, wherein the metal mask layer is made of one of the following materials selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
37. The structure as claimed in claim 33, wherein the mask layer is a silicon nitride layer or a silicon carbide layer.
38. The structure as claimed in claim 33, wherein the first stop layer is a silicon nitride layer or a silicon carbide layer.
39. The structure as claimed in claim 33, wherein the third dielectric layer is a second stop layer.
40. A structure for forming an opening on a substrate, comprising:
- a dielectric layer on the substrate;
- a plurality of mask layers at least comprising a metal mask layer on the dielectric layer; and
- an anti-reflection layer on the plurality of mask layers.
41. The structure as claimed in claim 40, wherein materials for forming the dielectric layer include inorganic polymer containing silicon.
42. The structure as claimed in claim 40, wherein the anti-reflection layer is a bottom anti-reflection coating layer made of fluid organic polymer.
43. The structure as claimed in claim 40, wherein the metal mask layer is made of one of the following materials selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
44. The structure as claimed in claim 40, wherein the mask layer is a silicon nitride layer or a silicon carbide layer.
45. A structure for forming an opening on a substrate, comprising:
- a first dielectric layer on the substrate;
- a stop layer on the first dielectric layer;
- a second dielectric layer on the stop layer;
- a plurality of mask layers at least comprising a metal mask layer on the second dielectric layer; and
- an anti-reflection layer on the plurality of mask layers.
46. The structure as claimed in claim 45, wherein materials for forming the first and second dielectric layers include inorganic polymer containing silicon.
47. The structure as claimed in claim 45, wherein the anti-reflection layer is a bottom anti-reflection coating layer made of fluid organic polymer.
48. The structure as claimed in claim 45, wherein the metal mask layer is made of one of the following materials selected from the group consisting of tantalum, tantalum nitride, titanium, titanium nitride, tungsten and tungsten nitride.
49. The structure as claimed in claim 45, wherein the mask layer is a silicon nitride layer or a silicon carbide layer.
50. The structure as claimed in claim 45, wherein the stop layer is a silicon nitride layer or a silicon carbide layer.
Type: Application
Filed: Dec 23, 2004
Publication Date: May 26, 2005
Applicant:
Inventors: Chih-Jung Wang (Hsinchu), Tong-Yu Chen (Hsinchu)
Application Number: 11/021,411