METHODS OF FORMING A PATTERN ON A SUBSTRATE
A method of forming a pattern on a substrate includes forming longitudinally elongated first lines and first sidewall spacers longitudinally along opposite sides of the first lines elevationally over an underlying substrate. Longitudinally elongated second lines and second sidewall spacers are formed longitudinally along opposite sides of the second lines. The second lines and the second sidewall spacers cross elevationally over the first lines and the first sidewall spacers. The second sidewall spacers are removed from crossing over the first lines. The first and second lines are removed in forming a pattern comprising portions of the first and second sidewall spacers over the underlying substrate. Other methods are disclosed.
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Embodiments disclosed herein pertain to methods of forming a pattern on a substrate, for example in the fabrication of integrated circuitry.
BACKGROUNDIntegrated circuits are often formed on a semiconductor substrate such as a silicon wafer or other semiconductive material. In general, layers of various materials which are semiconductive, conductive, or electrically insulative are used to form the integrated circuits. By way of examples, the various materials may be doped, ion implanted, deposited, etched, grown, etc. using various processes. A continuing goal in semiconductor processing is to strive to reduce the size of individual electronic components, thereby enabling smaller and denser integrated circuitry.
One technique for patterning and processing semiconductor substrates is photolithography. Such may include deposition of a patternable masking layer commonly known as photoresist. Such materials can be processed to modify their solubility in certain solvents, and are thereby readily usable to form patterns on a substrate. For example, portions of a photoresist layer can be exposed to actinic energy through openings in a radiation-patterning tool, such as a mask or reticle, to change the solvent solubility of the exposed regions versus the unexposed regions compared to the solubility in the as-deposited state. Thereafter, the exposed or unexposed regions can be removed, depending on the type of photoresist, to leave a masking pattern of the photoresist on the substrate. Adjacent areas of the underlying substrate next to the masked portions can be processed, for example by etching or ion implanting, to effect the desired processing of the substrate adjacent the masking material. In certain instances, multiple different layers of photoresist and/or a combination of photoresists with non-radiation sensitive masking materials are used. Further, patterns may be formed on substrates without using photoresist.
The continual reduction in feature sizes places ever greater demands on the techniques used to form those features. For example, photolithography is commonly used to form patterned features such as conductive lines and arrays of contact openings to underlying circuitry. A concept commonly referred to as “pitch” can be used to describe the sizes of the repeating features in conjunction with spaces immediately adjacent thereto. Pitch may be defined as the distance between an identical point in two neighboring features of a repeating pattern in a straight-line cross section, thereby including the maximum width of the feature and the space to the next immediately adjacent feature. However, due to factors such as optics and light or radiation wavelength, photolithography techniques tend to have a minimum pitch below which a particular photolithographic technique cannot reliably form features. Thus, minimum pitch of a photolithographic technique is an obstacle to continued feature size reduction using photolithography.
Pitch doubling or pitch multiplication is one proposed method for extending the capabilities of photolithographic techniques beyond their minimum pitch. Such typically forms features narrower than minimum photolithography resolution by depositing one or more spacer-forming layers to have a total lateral thickness which is less than that of the minimum capable photolithographic feature size. The spacer-forming layers are commonly anisotropically etched to form sub-lithographic features, and then the features which were formed at the minimum photolithographic feature size are etched from the substrate.
Using such techniques where pitch is actually halved, the reduction in pitch is conventionally referred to as pitch “doubling”. More generally, “pitch multiplication” encompasses increase in pitch of two or more times, and also of fractional values other than integers. Thus conventionally, “multiplication” of pitch by a certain factor actually involves reducing the pitch by that factor.
In addition to minimum feature size and placement of such features, it is often highly desirable that the features as-formed be uniform in dimension. Accordingly, uniformity when forming a plurality of features may also be of concern, and is increasingly a challenge as the minimum feature dimensions reduce.
Example methods of forming a pattern on a substrate are initially described with reference to
Only two lines 12 are shown for clarity in the figures, although likely thousands or millions of such lines may be fabricated over a substrate area of interest. Further, example lines 12 are shown as being of constant and equal width and height relative one another, as well as being equally spaced from one another by a distance equal to their width. Alternate shapes, sizes and/or configurations can be used.
Example substrate 14 is shown as comprising a base substrate 16 (e.g., semiconductor material) having material 18 and material 20 formed thereover. Material 20 may be used in forming a pattern over underlying substrate 16/18.
Material 20 may comprise suitable masking material, for example hard-masking material, and one or more antireflective coating materials. An example material 20 is a Si—O—N-comprising material formed to an example thickness from about 50 Angstroms to about 500 Angstroms. An example material 18 is undoped polysilicon formed to an example thickness from about 50 Angstroms to 2,000 Angstroms. Regardless, any of materials 16, 18, and 20 may be conductive, dielectric, and/or semiconductive.
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In one embodiment, second lines 36 are elevationally thicker between first lines 22 then atop of first lines 22, for example as is apparent in viewing
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Pattern 49 may be transferred in whole or in part to underlying substrate 16/18, if desired, in a number of different manners. Further, second sidewall spacers 46 that were over the ends of second lines 36 (not shown in
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In one embodiment, the pattern which is formed has a minimum feature width that is half of the half-pitch. For example, lines 34 in
In some embodiments, a method of forming a pattern on a substrate comprises forming longitudinally elongated first lines and first sidewall spacers longitudinally along opposite sides of the first lines elevationally over an underlying substrate. Longitudinally elongated second lines and second sidewall spacers are formed longitudinally along opposite sides of the second lines. The second lines and the second sidewall spacers cross elevationally over the first lines and the first sidewall spacers. The second sidewall spacers are removed from crossing over the first lines. The first and second lines are removed in forming a pattern comprising portions of the first and second sidewall spacers over the underlying substrate.
In some embodiments, a method of forming a pattern on a substrate comprises forming longitudinally elongated first lines elevationally over an underlying substrate. Longitudinally elongated second lines and masking material are formed longitudinally along opposite sides of the second lines. The second lines and the masking material cross elevationally over the first lines. The second lines and the masking material are elevationally thicker between the first lines than elevationally over the first lines. The masking material is removed from crossing over the first lines while leaving at least some of the masking material along sidewalls of the second lines between immediately adjacent first lines. The first and second lines are removed in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
In some embodiments, a method of forming a pattern on a substrate sequentially comprises forming longitudinally elongated first lines elevationally over an underlying substrate. Longitudinally elongated second lines are formed elevationally over and cross the first lines. A masking material is formed over tops and sides of the crossing first and second lines to less than fill void space between immediately adjacent second lines. The masking material is removed to expose the tops of the first and second lines. The first and second lines are removed in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
In some embodiments, a method of forming a pattern on a substrate sequentially comprises forming longitudinally elongated first lines elevationally over an underlying substrate. Longitudinally elongated second lines are formed elevationally over and cross the first lines. The second lines are elevationally thicker between the first lines than over tops of the first lines. Masking material is formed over tops, sides and ends of the crossing first and second lines to less than fill void space between immediately adjacent second lines. The masking material is removed from over all of the tops and all of the ends of the first and second lines while leaving at least some of the masking material along sidewalls of the second lines between immediately adjacent first lines. The first and second lines are removed in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
In compliance with the statute, the subject matter disclosed herein has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the claims are not limited to the specific features shown and described, since the means herein disclosed comprise example embodiments. The claims are thus to be afforded full scope as literally worded, and to be appropriately interpreted in accordance with the doctrine of equivalents.
Claims
1. A method of forming a pattern on a substrate, comprising:
- forming longitudinally elongated first lines and first sidewall spacers longitudinally along opposite sides of the first lines elevationally over an underlying substrate;
- forming longitudinally elongated second lines and second sidewall spacers longitudinally along opposite sides of the second lines, the second lines and the second sidewall spacers crossing elevationally over the first lines and the first sidewall spacers;
- removing the second sidewall spacers from crossing over the first lines; and
- removing the first and second lines in forming a pattern comprising portions of the first and second sidewall spacers over the underlying substrate.
2. The method of claim 1 comprising forming the first sidewall spacers as a ring around the respective first lines.
3. The method of claim 1 comprising forming the second sidewall spacers as a ring around the respective second lines.
4. The method of claim 1 wherein the first and second sidewall spacers are formed at the same time.
5. The method of claim 1 wherein forming the second sidewall spacers comprises depositing and subsequently anisotropically etching a masking material.
6. The method of claim 5 wherein the removing of the second sidewall spacers from crossing over the first lines comprises continuing the anisotropically etching of the masking material without stopping the etching between the forming of the second sidewall spacers and the removing of the second sidewall spacers from crossing over the first lines.
7. The method of claim 1 wherein the second sidewall spacers extend completely between immediately adjacent first lines after the removing of the second sidewall spacers from crossing over the first lines.
8. The method of claim 1 wherein the second lines are elevationally thicker between the first lines than atop the first lines.
9. The method of claim 1 wherein the underlying substrate has a planar elevationally outermost surface over which the first and second lines are received, each of the first and second lines extending to the elevationally outermost surface.
10. The method of claim 9 wherein the second lines are elevationally thicker between the first lines than atop the first lines.
11. The method of claim 10 comprising forming the first and second lines to have respective planar elevationally outermost surfaces, the elevationally outermost surfaces of the first lines being coplanar relative one another and the elevationally outermost surfaces of the second lines being coplanar relative one another.
12. The method of claim 1 comprising:
- after removing the first and second lines, forming fill material laterally of the portions of the first and second sidewall spacers;
- removing remaining of the portions of the first and second sidewall spacers in forming a contact opening mask comprising the fill material; and
- using the contact opening mask while etching contact openings into the underlying substrate.
13. The method of claim 1 comprising after removing the first and second lines, etching into the underlying substrate using remaining of the first and second sidewall spacers as an etch mask.
14. The method of claim 1 comprising forming predecessor second lines which are laterally trimmed in forming the second lines, the predecessor second lines having a pitch and a half thereof, the pattern having a minimum feature width that is half of the half-pitch.
15. The method of claim 1 wherein the portions of the first and second spacers in the pattern are generally rectangular in horizontal cross-section having adjacent sides of unequal length.
16. The method of claim 15 wherein the rectangular portions have longer sides that are about three times length of the shorter sides.
17. The method of claim 15 wherein the rectangular portions have longer sides that are more than three times length of the shorter sides.
18. A method of forming a pattern on a substrate, comprising:
- forming longitudinally elongated first lines elevationally over an underlying substrate;
- forming longitudinally elongated second lines and masking material longitudinally along opposite sides of the second lines, the second lines and the masking material crossing elevationally over the first lines, the second lines and the masking material being elevationally thicker between the first lines than elevationally over the first lines;
- removing the masking material from crossing over the first lines while leaving at least some of the masking material along sidewalls of the second lines between immediately adjacent first lines; and
- removing the first and second lines in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
19. The method of claim 18 comprising forming the masking material longitudinally along opposite sides of the first lines.
20. The method of claim 18 comprising forming the first and second lines to have respective planar elevationally outermost surfaces.
21. The method of claim 20 wherein the elevationally outermost surfaces of the first lines are coplanar relative one another and the elevationally outermost surfaces of the second lines are coplanar relative one another.
22. The method of claim 18 comprising forming the first and second lines to be of different compositions.
23. The method of claim 18 wherein forming the second lines comprises depositing and patterning a spin-on material.
24. A method of forming a pattern on a substrate sequentially comprising:
- forming longitudinally elongated first lines elevationally over an underlying substrate;
- forming longitudinally elongated second lines elevationally over and crossing the first lines;
- forming a masking material over tops and sides of the crossing first and second lines to less than fill void space between immediately adjacent second lines;
- removing the masking material to expose the tops of the first and second lines; and
- removing the first and second lines in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
25. The method of claim 24 wherein the removing of the masking material is from over all of the tops of the first and second lines.
26. A method of forming a pattern on a substrate sequentially comprising:
- forming longitudinally elongated first lines elevationally over an underlying substrate;
- forming longitudinally elongated second lines elevationally over and crossing the first lines, the second lines being elevationally thicker between the first lines than over tops of the first lines;
- forming a masking material over tops, sides and ends of the crossing first and second lines to less than fill void space between immediately adjacent second lines;
- removing the masking material from over all of the tops and all of the ends of the first and second lines while leaving at least some of the masking material along sidewalls of the second lines between immediately adjacent first lines; and
- removing the first and second lines in forming a pattern comprising spaced regions of the masking material over the underlying substrate.
27. The method of claim 26 wherein the removing of the masking material is by anisotropic etching.
28. The method of claim 26 wherein the removing of the masking material is by mask-less anisotropic etching.
Type: Application
Filed: Jul 6, 2012
Publication Date: Jan 9, 2014
Applicant: MICRON TECHNOLOGY, INC. (Boise, ID)
Inventors: Vishal Sipani (Boise, ID), Anton J. deVilliers (Boise, ID)
Application Number: 13/542,913
International Classification: H01L 21/311 (20060101);