DOUBLE EXPOSURE PATTERNING WITH CARBONACEOUS HARDMASK

• US 20090311635A1
• Filed: 12/19/2008
• Published: 12/17/2009
• Est. Priority Date: 06/16/2008
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: CHEN, YONGMEI, BENCHER, CHRISTOPHER D., NGAI, CHRISTOPHER SIU WING, CHEN, HUI W., YANG, SUSIE X., YU, JIAHUA, SHU, JEN, XU, XUMOU, DAI, HUIXIONG, HUNG, RAYMOND HOIMAN, DUANE, MICHAEL P., MACWILLIAMS, KENNETH, CHANG, CHORNG-PING
• Granted Patent: US 8,293,460 B2
• Time in Patent Office: Days
• US Class Current: 430/323
• 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: G03F 7/11 having cover layers or intermediate layers, e.g. subbing layers G03F7/091 - G03F7/093, B41N3/03 take precedence
• CPC Class Codes: G03F 7/2022 Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure

Abstract

Methods to pattern features in a substrate layer by exposing a photoresist layer more than once. In one embodiment, a single reticle may be exposed more than once with an overlay offset implemented between successive exposures to reduce the half pitch of the reticle. In particular embodiments, these methods may be employed to reduce the half pitch of the features printed with 65 nm generation lithography equipment to achieve 45 nm lithography generation CD and pitch performance.

Claims

1. A double exposure patterning method comprising:

providing a substrate layer under a photoresist layer;

exposing the photoresist layer to form a first pair of photoresist lines with a first space there between, the first pair of photoresist lines having a first alignment relative to the substrate layer;

offsetting the first alignment to have a second alignment;

re-exposing the photoresist layer to bifurcate at least one of the first pair of photoresist lines with a second space to form a pitch-reduced, critical dimension (CD) reduced double pattern comprising at least two photoresist lines and two spaces; and

etching the substrate layer to have the pitch-reduced, CD reduced, double pattern.

2. The method of claim 1, wherein the first space has a CD of X, each of the first pair of photoresist lines has a CD of approximately 3X, wherein the second alignment is offset from the first alignment by approximately 2X and wherein re-exposing the photoresist forms a double pattern of photoresist lines with a CD of X and spaces with a CD of X.

3. The method of claim 2, wherein X is approximately 32 nm and wherein the exposing and re-exposing of the photoresist layer is performed with a 65 nm lithographic scanner employing a single reticle for both exposures.

4. The method of claim 1, wherein offsetting the first alignment to the second alignment is performed in an x-dimension, but not in an orthogonal y-dimension.

5. The method of claim 4, wherein the first exposure of the photoresist layer further prints a line with a first portion with a major length extending in an x-direction and a second portion with a major length extending in an orthogonal, y-direction, wherein the width of the first portion is substantially less than that of the second portion;

and

wherein the second exposure of the photoresist layer trims the width of the second portion to be approximately equal to that of the first portion.

6. The method of claim 1, wherein offsetting the first alignment to the second alignment is performed in an x-dimension and in an orthogonal y-dimension.

7. The method of claim 1, wherein a CVD carbon layer is between the substrate layer and the photoresist layer and wherein the CVD carbon layer is etched to have the pitch-reduced, CD-reduced double pattern.

8. The method of claim 7, wherein the pitch-reduced, CD-reduced double pattern in the photoresist layer has a first line edge roughness (LER) and wherein the pitch-reduced, CD-reduced double pattern in the CVD carbon layer has a second LER, less than the first LER.

9. The method of claim 3, further comprising:

blading off a portion of a reticle after the exposure of the photo-resist layer and before the re-exposure of the photoresist layer.

10. The method of claim 3, further comprising:

scanning a first portion of the reticle to expose the photoresist layer; and

scanning a second portion, less than the first portion, to re-expose the photoresist layer and form a CD-reduced, pitch-reduce pattern corresponding to only a portion of the reticle.

11. A double exposure patterning method comprising:

providing a substrate layer under a CVD carbon layer, the CVD carbon layer covered with a bottom anti-reflective coating (BARC) layer and a photoresist layer over the BARC layer;

exposing the photoresist layer with a reticle having a first alignment relative to the substrate layer to form a first pair of photoresist lines with a first space there between, each line with a first CD that is less than three times a second CD of the space;

offsetting the first alignment between the reticle and the substrate layer to a second alignment;

re-exposing the photoresist layer with the reticle to bifurcate one of the first pair of photoresist lines with a second space to form a double pattern comprising at least two photoresist lines and two spaces, wherein each of the two photoresist lines has a third CD that is smaller than the second CD of the spaces;

etching the BARC layer with a polymerizing plasma etch process to form at least two BARC lines and two spaces, wherein the BARC lines and spaces are approximately equal to a fourth CD, smaller than the second CD but larger than the third CD;

etching the CVD carbon layer to form a double pattern comprising at least two CVD carbon lines and two spaces; and

etching the substrate layer to form a double pattern comprising at least two lines and two spaces, wherein the CD of the lines and spaces are approximately equal to the fourth CD.

12. The method of claim 11, wherein the exposing and re-exposing of the photoresist layer is performed with a 65 nm lithographic scanner, the third CD is between 45 nm and 60 nm and the fourth CD is between 30 nm and 45 nm.

13. The method of claim 11, wherein the BARC layer is at least half a thick as the photoresist layer, the CVD carbon layer is at least half as thick as the BARC layer and etching the CVD carbon layer removes substantially all of the photoresist.

14. The method of claim 11, wherein there is a dielectric anti-reflective coating (DARC) layer between the CVD carbon layer and the BARC layer, wherein the DARC layer thickness is between 10 nm and 30 nm, the BARC layer thickness is between 50 nm and 100 nm the photoresist layer thickness is between 110 nm and 150 nm and the CVD carbon layer thickness is between 30 nm and 75 nm.

15. The method of claim 11, wherein the substrate layer is polysilicon.

16. The method of claim 11, wherein the least two photoresist lines have a first line edge roughness (LER) and wherein the at least two CVD carbon lines have a second LER, less than the first LER.

17. A computer readable media with instructions stored thereon, which when executed by a processing system cause the system to perform a method comprising:

providing a substrate layer under a photoresist layer;

exposing the photoresist layer to form a first pair of lines with a first space there between, the first pair of lines having a first alignment relative to the substrate layer; and

offsetting the first alignment to have a second alignment;

re-exposing the photoresist layer with to bifurcate at least one of the first pair of photoresist lines with a second space to form a pitch-reduced, CD reduced double pattern comprising at least two photoresist lines and two spaces.

18. The computer readable medium of claim 17, wherein the first space has a CD of X, each of the first pair of lines has a CD of 3X, and wherein re-exposing the photoresist layer forms a double pattern of lines with a CD of X and spaces with a CD of X.

19. The computer readable medium of claim 17, wherein X is 32 nm and wherein the exposing and re-exposing of the photoresist layer is performed with a 65 nm lithographic scanner.

20. The computer readable medium of claim 17, wherein a CVD carbon layer is between the substrate layer and the photoresist layer and wherein the CVD carbon layer is etched to have the pitch-reduced, CD-reduced double pattern.