Method of making an antireflective structure

• US 6,228,740 B1
• Filed: 11/19/1999
• Issued: 05/08/2001
• Est. Priority Date: 04/18/1997
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Niroomand, Ardavan, Gonzalez, Fernando
• Primary Examiner(s): Tsai, H Jey
• Application Number:
  US09/443,666
• Time in Patent Office: 536 Days
• Field of Search: 438/253-256, 438/396-399, 438/964, 438/636
• US Class Current: 438/398
• CPC Class Codes: G03F 7/091 characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264
• CPC Class Codes: Y10S 438/952 Utilizing antireflective layer
• CPC Class Codes: Y10S 438/964 Roughened surface

Abstract

Inventive antireflective structures comprise a semiconductor substrate having thereon a combination of a plurality of layers that either that absorb reflected light or that dissipate reflected light into patterns and intensities that do not substantially alter photoresist material on the semiconductor substrate. The semiconductor substrate has formed thereon a feature having a width of less than about 0.25 microns. Antireflective structures contemplated include a first layer of polysilicon and first layer of silicon nitride material that is formed upon the first layer of polysilicon. The antireflective structure has the ability to scatter unabsorbed light into patterns and intensities that are substantially ineffective to alter photoresist material exposed to said patterns and intensities. A first antireflective structure comprises a first layer of polysilicon disposed upon on a semiconductor substrate, a second layer of silicon nitride material disposed upon the first layer of polysilicon, and a masking layer disposed upon the second layer of silicon nitride material. A second antireflective structure comprises a first layer of polysilicon disposed upon on a semiconductor substrate, a first layer of nitride material disposed upon the first layer of polysilicon, a second layer of polysilicon disposed upon the first layer of silicon nitride material, and a masking layer disposed upon the second layer of polysilicon. A third antireflective structure comprises a first layer of polysilicon disposed upon on a semiconductor substrate, a first layer of silicon nitride material disposed upon the first layer of polysilicon, a second layer of polysilicon disposed upon the first layer of silicon nitride material, a second layer of silicon nitride material disposed upon the second layer of polysilicon, and a masking layer disposed upon the second layer of silicon nitride material.

Claims

1. A method of forming a structure comprising:

forming a first layer on a semiconductor substrate, said first layer including at least one hemispherical grain (HSG) polysilicon layer, said at least one HSG polysilicon layer having a thickness of less than about 500 Å

; and

forming a second layer disposed conformably upon said first layer, said second layer, composed of a nitride material having a thickness in a range from about 200 Å

to about 1,000 Å

.

2. The method as defined in claim 1, further comprising:

forming and patterning a layer of photoresist upon said second layer to expose first and second points on said second layer.

3. The method as defined in claim 2, wherein said first and second points on said second layer are separated a width of less than about 0.25 microns and are adjacent to a mask structure that is at least one of:

a portion of said photoresist layer upon said second layer that;

projects from said second layer; and

extends continuously between the first and second points on said second layer; and

primary and secondary portions of said photoresist layer that project from said second layer, wherein the primary portion of the photoresist layer is adjacent to the first point on the second layer and the secondary portion of the photoresist layer is adjacent to the second point on the second layer, and wherein the second layer is continuously uncovered by said photoresist layer between the first and second points so as to be exposed.

4. The method as defined in claim 2, wherein said second layer includes a layer of polysilicon having a grain size less than about 500 Å

.

5. The method as defined in claim 2, wherein said second layer comprises silicon nitride.

6. The method as defined in claim 2, wherein said second layer comprises Si_xN where x is in a range from greater than 0.75 to 10.

7. The method as defined in claim 2, wherein a feature surface on said second layer extends between the first and second points, the method further comprising defining under said feature surface a patterned space having a width not greater than that of the feature surface, said patterned space being selected from the group consisting of a contact hole, a via, a wiring trench, an active area and an isolation trench.

8. The method as defined in claim 2, wherein said second layer includes a layer of polysilicon upon which said at least one mask structure is situated.

9. The method as defined in claim 2, wherein said second layer includes a layer of polysilicon, wherein a layer of nitride material is formed above said polysilicon, and wherein said layer of photoresist is situated upon said layer of nitride material.

10. The method as defined in claim 2, wherein a feature surface on said second layer extends between the first and second points, the method further comprising:

forming a recess under said feature surface in said first layer, said second layer, and said semiconductor substrate having a width less than or equal to that of said feature surface;

filling said recess with a dielectric material;

removing all material above an upper level of said recess to form a planar surface including co-planar surfaces on said first layer and said dielectric material; and

forming a primary layer upon said planar surface composed of material selected from the group consisting of HSG polysilicon and a nitride material.

11. The method as defined in claim 10, further comprising:

forming a secondary layer upon said primary layer said secondary layer being selected from the group consisting of HSG polysilicon and a nitride material.

12. The method as defined in claim 2, wherein forming the second layer is by a method selected from the group consisting of CVD and thermal transformation of polysilicon.

13. The method as defined in claim 2, wherein forming and patterning the layer of photoresist upon said second layer to expose first and second points on said second layer comprises exposing said photoresist layer to an incident patterning light, and wherein the first and second layer have a combined reflectivity to said incident patterning light of less than about 10% of incident patterning light.

14. The method as defined in to claim 2, wherein said at least one HSG polysilicon layer is formed so as to have said grain size by a process selected from the group consisting of heat treatment of said at least one HSG polysilicon layer, etching a surface upon said semiconductor substrate prior to formation of said at least one HSG poiysilicon layer, and flashing of entrapped undisassociated CVD feed material in a deposition of said at least one HSG polysilicon layer.

15. A method of forming a submicron surface on a structure comprising:

forming a first layer on a semiconductor substrate, said first layer including at least one HSG polysilicon layer, said at least one HSG poiysilicon layer having a thickness of less than about 500 Å

;

forming a second layer disposed conformably upon said first layer, said second layer being composed of a nitride material having a thickness in a range from about 200 Å

to about 1,000 Å

; and

forming and patterning a layer of photoresist upon said second layer to expose first and second points on said second layer, wherein said first and second points on said second layer are separated by a width of less than about 0.25 microns and are adjacent to a mask structure that is at least one of;

a portion of said photoresist layer upon said second layer that;

projects from said second layer; and

extends continuously between the first and second points on said second layer; and

primary and secondary portions of said photoresist layer that project from said second layer, wherein the primary portion of the photoresist layer is adjacent to the first point on the second layer and the secondary portion of the photoresist layer is adjacent to the second point on the second layer, and wherein the second layer is continuously uncovered by said photoresist layer between the first and second points so as to be exposed.

16. The method as defined in claim 15, wherein said second layer includes a layer of polysilicon having grain size less than about 500 Å

.

17. The method as defined in claim 15, wherein said second layer comprises silicon nitride.

18. The method as defined in claim 15, wherein said second layer comprises Si_xN where x is in a range from greater than 0.75 to 10.

19. The method as defined in claim 15, wherein said second layer includes a layer of polysilicon upon which said layer of photoresist is situated.

20. The method as defined in claim 15, wherein said second layer includes a layer of polysilicon, wherein a layer of nitride material is formed above said polysilicon, and wherein said layer of photoresist is situated upon said layer of nitride material.

21. The method as defined in claim 15, wherein a feature surface on said second layer extends between the first and second points, the method further comprising:

forming a recess under said feature surface in said first layer, said second layer, and said semiconductor substrate having a width less than or equal to that of said feature surface;

filling said recess with a dielectric material;

removing all material above an upper level of said recess to form a planar surface including co-planar surfaces on said first layer and said dielectric material; and

forming a primary layer upon said planar surface composed of material selected from the group consisting of HSG polysilicon and a nitride material.

22. The method as defined in claim 21, further comprising:

forming a secondary layer upon said primary layer, said secondary layer being selected from the group consisting of HSG polysilicon and a nitride material.

23. A method of forming a submicron surface on a structure comprising:

forming a first layer on a semiconductor substrate, said first layer including at least one HSG polysilicon layer, said at least one HSG polysilicon layer having a thickness of less than about 500 Å and

being formed so as to have said grain size by a process selected from the group consisting of heat treatment of said at least one HSG polysilicon layer, etching a surface upon said semiconductor substrate prior to formation of said at least one HSG polysilicon layer, and flashing of entrapped undisassociated CVD feed material in a deposition of said at least one HSG polysilicon layer;

forming a second layer disposed conformably upon said first layer, said second layer being composed of a nitride material having a thickness in a range from about 200 Å

to about 1,000 Å

; and

forming and patterning a layer of photoresist upon said second layer to expose first and second points on said second layer so as to expose said photoresist layer to an incident patterning light, and wherein the first and second layer have a combined reflectivity to said incident patterning light of less than about 10% of incident patterning light.

24. The method as defined in claim 23, wherein a feature surface on said second layer extends between the first and second points, the method further comprising:

forming a recess under said feature surface in said first layer, said second layer, and said semiconductor substrate having a width less than or equal to that of said feature surface;

filling said recess with a dielectric material;

removing all material above an upper level of said recess to form a planar surface including co-planar surfaces on said first layer and said dielectric material; and

forming a primary layer upon said planar surface composed of material selected from the group consisting of HSG polysilicon and a nitride material.

25. The method as defined in claim 24, further comprising:

forming a secondary layer upon said primary layer, said secondary layer being selected from the group consisting of HSG polysilicon and a nitride material.

26. The method as defined in claim 23, wherein forming the second layer is by a method selected from the group consisting of CVD and thermal transformation of polysilicon.

27. The method as defined in claim 23, wherein a feature surface on said second layer extends between the first and second points, the method further comprising defining under said feature surface a patterned space having a width not greater than that of the feature surface, said patterned space being selected from the group consisting of a contact hole, a via, a wiring trench, an active area and an isolation trench.

28. The method as defined in claim 23, wherein said second layer further includes a layer of polysilicon upon which said at least one mask structure is situated.

29. The method as defined in claim 23, wherein said second layer further includes a layer of polysilicon, wherein a layer of nitride material is formed above said polysilicon, and wherein said layer of photoresist is situated upon said layer of nitride material.

30. A method of forming a sub-micron surface on a structure comprising:

forming a first layer on a semiconductor substrate, said first layer including at least one HSG polysilicon layer, said at least one HSG polysilicon layer having a thickness of less than about 500 Å

, wherein said at least one HSG polysilicon layer is former so as to have said grain size by a process selected from the group consisting of heat treatment of said at least one HSG polysilicon layer, etching a surface upon said semiconductor substrate prior to formation of said at least one HSG polysilicon layer, and flashing of entrapped undisassociated CVD feed material in a deposition of said at least one HSG polysilicon layer;

forming a second layer disposed conformably upon said first layer, said second layer having a thickness in a range from about 200 Å

to about 1,000 Å

; and

forming and patterning a layer of photoresist upon said second layer to expose first and second points on said second layer, wherein a feature surface on said second layer extends to terminate at the first and second points, wherein said first and second points on said second layer are separated by a width of less than about 0.25 microns and are adjacent to a mask structure that is at least one of;

a portion of said photoresist layer upon said second layer that;

projects from said second layer; and

extends continuously between the first and second points on said second layer; and

primary and secondary portions of said photoresist layer that project from said second layer, wherein the primary portion of the photoresist layer is adjacent to the first point on the second layer and the secondary portion of the photoresist layer is adjacent to the second point on the second layer, and wherein the second layer is continuously uncovered by said photoresist layer between the first and second points so as to be exposed

forming a recess under said feature surface in said first layer, within said second layer, and within said semiconductor substrate having a width less than or equal to that of said feature surface;

filling said recess with a dielectric material;

removing all material above an upper level of said recess to form a planar surface including co-planar surfaces on said first layer and said dielectric material;

forming a primary layer upon said planar surface composed of material selected from the group consisting of HSG polysilicon and a nitride material; and

forming a nitride material upon said primary layer by a method selected from the group consisting of CVD and thermal transformation of polysilicon material.

31. A method of an antireflective structure comprising:

forming a first layer on a semiconductor substrate, said first layer including at least one HSG polysilicon layer, said at least one HSG polysilicon layer having a thickness of less than about 500 Å and

being formed so as to have said grain size by a process selected from the group consisting of heat treatment of said at least one HSG polysilicon layer, etching a surface upon said semiconductor substrate prior to formation of said at least one HSG polysilicon layer, and flashing of entrapped undisassociated CVD feed material in a deposition of said at least one HSG polysilicon layer;

forming a second layer disposed conformably upon said first layer, said second layer;

having a thickness in a range from about 200 Å

to about 1,000 Å

,

having a feature surface on said second layer extends between the first and second points, there being defined under said feature surface a patterned space having a width not greater than that of the feature surface, said patterned space being selected from the group consisting of a contact hole, a via, a wiring trench, an active area and an isolation trench; and

being formed of a nitride material by a process selected from the group consisting of CVD and thermal transformation of polysilicon;

forming and patterning a layer of photoresist upon said second layer to expose first and second points on said second layer so as to expose said photoresist layer to an incident patterning light, and wherein the first and second layer have a combined reflectivity to said incident patterning light of less than about 10% of incident patterning light;

forming a recess under said feature surface in said first layer, said second layer, and said semiconductor substrate having a width less than or equal to that of said feature surface;

filling said recess with a dielectric material;

removing all material above an upper level of said recess to form a planar surface including co-planar surfaces on said first layer and said dielectric material; and

forming a primary layer upon said planar surface composed of material selected from the group consisting of HSG polysilicon and a nitride material;

forming a secondary layer upon said primary layer, said secondary layer being selected from the group consisting of polysilicon and a nitride material.

32. A method of forming a structure comprising:

forming a plurality of alternating layers of a first composition and a second composition;

wherein;

each said alternating layer contacting another said alternating layer;

for each said alternating layer, the second composition is formed upon the first composition;

the first composition includes at least one HSG polysilicon layer that has a thickness of less than about 500 Å

; and

the second composition includes a nitride material having a thickness in a range from about 200 Å

to about 1,000 Å

.

33. The method as defined in claim 32, wherein the second composition includes a layer of polysilicon having a grain size less than about 500 Å

.

34. The method as defined in claim 32, further comprising:

forming and patterning a layer of photoresist upon said plurality of alternating layers to expose thereon first and second points, wherein said first and second points on said plurality of alternating layers are separated a width of less than about 0.25 microns and are adjacent to a mask structure that is at least one of;

a portion of said photoresist layer upon said plurality of alternating layers that;

projects from said plurality of alternating layers; and

extends continuously between the first and second points on said plurality of alternating layers; and

primary and secondary portions of said photoresist layer that project from said plurality of alternating layers, wherein the primary portion of the photoresist layer is adjacent to the first point on said plurality of alternating layers and the secondary portion of the photoresist layer is adjacent to the second point on said plurality of alternating layers, and wherein said plurality of alternating layers are continuously uncovered by said photoresist layer between the first and second points so as to be exposed.