Methods for making EUV patternable hard masks

Abstract

This invention proposes a method for fabricating EUV-patternable thin films on a semiconductor substrate. The method includes: mixing a vapor stream of an organometallic precursor with a vapor stream of a reverse reactant to form a polymerized organometallic material; and depositing the organometallic polymer material onto the surface of the semiconductor substrate. The mixing and deposition operations can be performed by chemical vapor deposition (CVD), atomic layer deposition (ALD), and combinations of ALD and CVD, such as discontinuous ALD-like processes, wherein the metal precursor and the reverse reactant are separated both temporally and spatially.

Description

[Technical Field] This technology relates to systems and methods for manufacturing lithography masks, which are used in semiconductor manufacturing. Specifically, this technology provides methods, apparatus, and assemblies for generating patternable hard masks on a substrate used in the manufacture of semiconductor devices. [Cross-reference to related applications] This application claims priority to U.S. Provisional Patent Application No. 62 / 782,578, filed December 20, 2018, and U.S. Provisional Patent Application No. 62 / 670,644, filed May 11, 2018. The full contents of these applications are incorporated herein by reference. [Previous Technology] The prior art provided herein is for the purpose of providing a general overview of the background of this technology. Within the scope described in this prior art section, the inventor's work and the implementation of the prior art at the time of application are not worthy of being considered prior art and are neither expressly nor impliedly recognized as prior art against this technology. The fabrication of semiconductor devices (such as integrated circuits) involves a multi-step process called lithography. Typically, the process includes depositing material on a wafer and patterning the material using lithography techniques to form structural features of the semiconductor device (e.g., contacts, vias, interconnects, transistors, and circuitry). Typical lithography processes known in the art include the following steps: preparing a substrate; applying photoresist, for example by spin coating; exposing the photoresist to a desired pattern, such that the exposed areas of the photoresist are more or less soluble in a developer solution; developing the photoresist by applying a developer solution to remove the exposed or unexposed areas; and subsequent processing to create features on the photoresist-removed substrate area, such as by etching or material deposition. The advancements in semiconductor design have created and have been driven by the need to fabricate smaller features on semiconductor substrate materials. This technological progress, as described in Moore's Law, sees the transistor density in densely integrated circuits doubling every two years. In fact, advancements in chip design and manufacturing have enabled modern microprocessors to incorporate billions of transistors and other circuit features onto a single chip. These features can be on the 22-nanometer (nm) scale or smaller, and in some cases, less than 10 nm. It is challenging to reliably and reproducibly produce a microshape mask with sufficient resolution when fabricating components with such small feature parts. Current microfilm processes usually use ultraviolet (UV) light of 193nm to expose photoresist. The fact that the wavelength of light is significantly larger than the size of the characteristic part desired to be generated on the semiconductor substrate generates an innate problem. Complex resolution enhancement techniques, such as multiple patterning, are needed to realize feature part dimensions smaller than the wavelength of light. Therefore, the development of light microshaping technique using shorter wavelengths of light such as extreme ultraviolet radiation (EUV) with wavelengths from 10nm to 15nm, such as 13.5nm is of significant significance and research results. However, the EUV photomicrography process can be challenging, including low energy output and light leakage during patterning. Organic chemical magnification photoresistors (CARs) similar to those used for 193nm UV microfilming have potential drawbacks when used for EUV microfilming, particularly when they have low absorption coefficients in the EUV region and the diffusion of light-activated chemical species may result in blurring or rough line edges. Furthermore, in order to provide the etching resistance required when patterning the overlying element layer, small feature parts patterned in the well-known CAR material may result in high aspect ratios and risk of pattern collapse. Therefore, EUV photoresist materials still need to be improved to have properties such as reduced thickness, greater absorption, and greater etching resistance. [Invention Contents] This technology provides a method for fabricating thin films on a substrate, particularly a semiconductor substrate, which can be patterned using EUV. This method includes generating a polymerized organometallic material in a vapor phase and depositing it onto the substrate. Specifically, a method for fabricating an EUV-patternable thin film on the surface of a semiconductor substrate includes: mixing a vapor stream of an organometallic precursor with a vapor stream of a counter-reactant to form a polymerized organometallic material; and depositing an organometallic polymer-like material onto the surface of the semiconductor substrate. In some embodiments, the vapor stream contains one or more organometallic precursors. In some embodiments, the vapor stream contains one or more counter-reactants. In some embodiments, the mixing and deposition operations are performed in a continuous chemical vapor deposition (CVD), atomic layer deposition (ALD) process, or a combination of ALD and CVD, such as a discontinuous ALD-like process, wherein the metal precursor and the counter-reactant are separated both temporally and spatially. This technology also provides a method for forming patterns on the surface of a semiconductor material, including exposing areas of an EUV patternable thin film manufactured according to this technology using a patterned EUV beam (typically under a relatively high vacuum), followed by removing the wafer from the vacuum and performing post-exposure baking in ambient air. The exposure results in one or more exposed areas, such that the film includes one or more unexposed areas not exposed to EUV light. The chemical and physical differences between the exposed and unexposed areas can be utilized to further process the coated substrate. Other applications of this technology will become apparent from the implementation methods, claims, and drawings. The implementation methods and specific examples are for illustrative purposes only and are not intended to limit the scope of this technology.

Implementation Method

Claims

1. A method for fabricating an EUV patternable film on the surface of a substrate, comprising: The substrate is provided to a heated base, the heated base being set at a surface temperature; A vapor stream of an organometallic precursor is mixed with a vapor stream of a reverse reactant to form a polymerized organometallic material; and the organometallic material is deposited on the surface of the substrate at a deposition rate to form the EUV patternable film, wherein the deposition rate is inversely proportional to the surface temperature, and wherein the temperature of the substrate is equal to or lower than the temperature of the vapor stream of the organometallic precursor and the temperature of the vapor stream of the reverse reactant.

2. The method for fabricating an EUV patternable film on the surface of a substrate as claimed in claim 1, wherein the organometallic precursor has the chemical formula MaRbLc, wherein: M is a metal with an atomic absorption profile equal to or greater than 1 × 10⁷ cm² / mol; R is an alkyl group with the chemical formula CnH₂n + 1, where n ≥ 3; L is a ligand or ion that reacts with the reverse reactant; a ≥ 1; b ≥ 1; and c ≥ 1.

3. The method for manufacturing an EUV patternable film on the surface of a substrate as claimed in claim 2, wherein M is selected from the group consisting of tin, bismuth, antimony, and combinations thereof; R is selected from the group consisting of isopropyl, n-propyl, tert-butyl, isobutyl, n-butyl, sec-butyl, isopentyl, n-pentyl, tert-pentyl, sec-pentyl, and mixtures thereof; and L is selected from the group consisting of amines, alkoxy groups, carboxylates, halogens, and mixtures thereof.

4. The method for fabricating an EUV patternable film on the surface of a substrate as claimed in claim 1 or 3, wherein the organometallic precursor is tert-butyltris(dimethylamino)tin, isobutyltris(dimethylamino)tin, n-butyltris(dimethylamino)tin, sec-butyltris(dimethylamino)tin, isopropyltris(dimethylamino)tin, n-propyltris(diethylamino)tin, and similar alkyltris(tert-butoxy)tin compounds.

5. The method for fabricating an EUV patternable film on the surface of a substrate, as claimed in any one of claims 1 to 3, wherein the organometallic precursor is partially fluorinated.

6. The method for manufacturing an EUV patternable film on the surface of a substrate, as claimed in any one of claims 1 to 3, wherein the reverse reactant is selected from the group consisting of water, hydrogen peroxide, dihydroxy or polyhydroxy alcohol, hydrogen sulfide, hydrogen disulfide, trifluoroacetaldehyde monohydrate, fluorinated dihydroxy alcohol or fluorinated polyhydroxy alcohol, and fluorinated ethylene glycol.

7. The method for fabricating an EUV patternable film on the surface of a substrate, as claimed in any one of claims 1 to 3, wherein the mixing and deposition system is performed in a continuous chemical vapor deposition process.

8. A method for manufacturing an EUV patternable film on the surface of a substrate, as claimed in any one of claims 1 to 3, wherein the substrate includes an underlying topographic feature portion.

9. A method for forming a photomask precursor on the surface of a semiconductor substrate, comprising: The semiconductor substrate is provided to a heated base, the heated base being set at a surface temperature; A vapor stream of an organometallic precursor is mixed with a vapor stream of a reverse reactant to form a polymerized organometallic material; the organometallic material is deposited on the surface of a semiconductor substrate at a deposition rate to form an EUV patternable film, wherein the deposition rate is inversely proportional to the surface temperature, and wherein the temperature of the semiconductor substrate is equal to or lower than the temperatures of the vapor streams of the organometallic precursor and the reverse reactant; optionally, the film is heated; a region of the EUV patternable film is exposed to EUV light to form an exposed film region, such that the EUV patternable film also includes an unexposed film region not exposed to EUV light; and optionally, the EUV patternable film is heated to form a mask precursor including the exposed region and the unexposed region.

10. The method of forming a photomask precursor on the surface of a semiconductor substrate as claimed in claim 9, wherein the exposed region of the photomask precursor is insoluble in a selected solvent, and the unexposed region of the photomask precursor is soluble in the solvent.

11. The method of claim 10 for forming a photomask precursor on the surface of a semiconductor substrate further includes removing the unexposed area of ​​the photomask precursor with the solvent.

12. The method of forming a photomask precursor on the surface of a semiconductor substrate as claimed in claim 9 or 10, wherein the exposed area of ​​the photomask precursor includes a reactive surface portion.

13. The method of claim 12 for forming a photomask precursor on the surface of a semiconductor substrate further includes selectively depositing a second material on the surface of the exposed area, wherein the solubility contrast and etch selectivity between the exposed area and the unexposed area will increase.

14. The method of forming a photomask precursor on the surface of a semiconductor substrate as claimed in claim 13, wherein the deposition of the second material is performed using an atomic layer deposition process.

15. The method for forming a photomask precursor on the surface of a semiconductor substrate as claimed in claim 9 further includes dry development of the EUV patternable film after exposure.

16. A method for forming a photomask precursor on the surface of a semiconductor substrate, as claimed in any one of claims 9-11, wherein the organometallic precursor has the chemical formula MaRbLc, wherein: M is a metal with an atomic absorption profile equal to or greater than 1 × 10⁷ cm² / mol; R is an alkyl group with the chemical formula CnH₂n + 1, where n ≥ 3; L is a ligand or ion that reacts with the reverse reactant; a ≥ 1; b ≥ 1; and c ≥ 1.

17. The method of forming a photomask precursor on the surface of a semiconductor substrate as claimed in claim 16, wherein M is selected from the group consisting of tin, bismuth, antimony, and combinations thereof; R is selected from the group consisting of isopropyl, n-propyl, tert-butyl, isobutyl, n-butyl, sec-butyl, isopentyl, n-pentyl, tert-pentyl, sec-pentyl, and mixtures thereof; and L is selected from the group consisting of amines, alkoxy groups, carboxylates, halogens, and mixtures thereof.

18. A method for forming a photomask precursor on the surface of a semiconductor substrate, as claimed in any one of claims 9-11, wherein the organometallic precursor is tert-butyltris(dimethylamino)tin, isobutyltris(dimethylamino)tin, n-butyltris(dimethylamino)tin, sec-butyltris(dimethylamino)tin, isopropyltris(dimethylamino)tin, n-propyltris(diethylamino)tin, and similar alkyltris(tert-butoxy)tin compounds.

19. A method for forming a photomask precursor on the surface of a semiconductor substrate, comprising: (a) Providing the semiconductor substrate to a heated base, the heated base being set at a surface temperature; (b) Mixing a vapor stream of an organometallic precursor with a vapor stream of a reverse reactant to form a polymerized organometallic material, wherein (i) the organometallic precursor has the chemical formula MaRbLc, where: M is a metal having an atomic absorption cross-section equal to or greater than 1 × 10⁷ cm² / mol; R is an alkyl group having the chemical formula CnH₂n + 1, where n ≥ 3; L is a ligand or ion reacting with the reverse reactant; a ≥ 1; b ≥ 1; and c ≥ 1; and (ii) the reverse reactant is selected from the group consisting of water, peroxides, dihydroxyols or polyhydroxyols, fluorinated dihydroxyols or fluorinated polyhydroxyols, fluorinated ethylene glycol, and mixtures thereof; (c) (d) depositing the organometallic material on the surface of the semiconductor substrate at a deposition rate to form an EUV patternable film, wherein the deposition rate is inversely proportional to the surface temperature, wherein the temperature of the semiconductor substrate is equal to or lower than the temperature of the vapor stream of the organometallic precursor and the temperature of the vapor stream of the reverse reactant; (e) optionally heating the film; (f) exposing a region of the EUV patternable film to EUV light to form an exposed film region, such that the EUV patternable film also includes an unexposed film region not exposed to the EUV light; and (c) dry developing the EUV patternable film.

20. A method for forming a photomask precursor on the surface of a semiconductor substrate, as claimed in any one of claims 9-11 and 19, wherein the organometallic precursor is partially fluorinated.

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