Method for depositing and reflow of a high quality etch resistant gapfill dielectric film

Methods for depositing a gapfill dielectric film that may be utilized for multi-colored patterning processes are provided. In one implementation, a method for processing a substrate is provided. The method comprises filling the one or more features of a substrate with a dielectric material. The dielectric material is a doped silicate glass selected from borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). The method further comprises treating the substrate with a high-pressure anneal in the presence of an oxidizer to heal seams within the dielectric material. The high-pressure anneal comprises supplying an oxygen-containing gas mixture on a substrate in a processing chamber, maintaining the oxygen-containing gas mixture in the processing chamber at a process pressure at greater than 2 bar and thermally annealing the dielectric material in the presence of the oxygen-containing gas mixture.

BACKGROUND

Field

Implementations described herein generally relate to a method for depositing a gapfill dielectric film that may be utilized for patterning processes such as multi-colored patterning processes.

Description of the Related Art

Semiconductor device processing is used to create integrated circuits that are present in electrical devices.

Conventionally, in the fabrication of integrated circuits, photolithography scanners using 193 nanometer (nm) wavelength lasers and numerical apertures of 1.35 have reached fundamental printing limits of 40 nm to 45 nm. However, there are demands and device trends for smaller feature sizes not obtainable by photolithography. Multi-color patterning processes are used to form lines, vias, trenches, contacts, devices, gates and other features on substrates Multi-color patterning processes form smaller features not obtainable by conventional photolithography processes.

In order to form features having smaller dimensions, such as sub-nano dimensions, gapfill layers are used to fill gaps formed between spacer layers disposed on mandrels formed on substrates. The spacer layers and/or mandrels are removed to form positive tones (lines) or negative tones (trenches) with small dimensions. Therefore, the gapfill layers should survive etching processes that remove the spacer layers and/or mandrels and should be thermally stable to withstand processing.

Accordingly, what is needed in the art are improved methods for forming gapfill layers.

SUMMARY

Implementations described herein generally relate to a method for depositing a gapfill dielectric film that may be utilized for multi-colored patterning processes. In one implementation, a method for processing a substrate is provided. The method comprises filling the one or more features of a substrate with a dielectric material. The dielectric material is a doped silicate glass selected from borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). The method further comprises treating the substrate with a high-pressure anneal in the presence of an oxidizer to heal seams within the dielectric material. The high-pressure anneal comprises supplying an oxygen-containing gas mixture on a substrate in a processing chamber, maintaining the oxygen-containing gas mixture in the processing chamber at a process pressure at greater than 2 bar and thermally annealing the dielectric material in the presence of the oxygen-containing gas mixture.

In another implementation, a method for processing a substrate is provided. The method comprises thermally treating a dielectric layer disposed on a substrate at a pressure greater than 2 bar The dielectric layer is a doped silicate glass selected from borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). The method further comprises maintaining a substrate temperature less than 500 degrees Celsius during thermally treating the dielectric layer.

In yet another implementation, a method of processing a substrate is provided. The method comprises forming a dielectric layer on a substrate by a chemical vapor deposition process. The dielectric layer is a doped silicate glass selected from borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). The method further comprises thermally treating the dielectric layer on the substrate at a pressure greater than 2 bar while maintaining the substrate temperature less than 500 degrees Celsius. The method further comprises exposing the substrate to a dry anneal process.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.

DETAILED DESCRIPTION

The following disclosure describes high-pressure annealing processes that may be used to cure defects in gapfill dielectric films. Certain details are set forth in the following description and inFIGS. 1-3to provide a thorough understanding of various implementations of the disclosure. Other details describing well-known structures and systems often associated with deposition of gapfill dielectric films and high-pressure annealing processes are not set forth in the following disclosure to avoid unnecessarily obscuring the description of the various implementations.

Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular implementations. Accordingly, other implementations can have other details, components, dimensions, angles and features without departing from the spirit or scope of the present disclosure. In addition, further implementations of the disclosure can be practiced without several of the details described below.

Implementations described herein will be described below in reference to a high-pressure annealing process that can be carried out using a high-pressure annealing process. Other tools capable of performing high-pressure annealing processes may also be adapted to benefit from the implementations described herein. In addition, any system enabling high-pressure annealing processes described herein can be used to advantage. The apparatus description described herein is illustrative and should not be construed or interpreted as limiting the scope of the implementations described herein.

There is a need for semi-compatible films with good gapfill to enable multi-color patterning by having high etch selectivity (e.g., >20:1) between the various materials. Doped silicate glass films (e.g., borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG)) have good etch selectivity but poor gapfill at low temperatures since reflow occurs at temperatures greater than 700 degrees Celsius. State of the art processes use anneals at temperatures greater than 600 degrees Celsius in various ambient including steam to reflow borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). Despite superior etch selectivity, as thermal budgets decrease to temperatures below 500 degrees Celsius doped silicate glass films such as BPSG, BSG and PSG have fallen out of favor. Although dopant concentration can be increased to further reduce the thermal budget of these doped silicate glass films, increasing dopant concentration alone cannot achieve current thermal budgets of less than 500 degrees Celsius. Implementations of the present disclosure use a steam anneal performed at high pressures (e.g., greater than one atmosphere) to enable reflow of doped silicate glass films at a temperature less than 500 degrees Celsius. In some implementations, doped silicate glass is exposed to a multi-step anneal process. In one implementation, the multi-step anneal process includes—(1) exposing the doped silicate glass to a steam anneal at high pressure to enable reflow; and the (2) exposing the doped silicate glass to a dry environment anneal to eliminate any remaining moisture. The ability to use doped silicate glass films for gapfill at low thermal budgets provides a new material scheme for multi-color patterning to enable self-alignment.

FIG. 1is a flow diagram of a method100for processing a substrate, according to one or more implementations of the present disclosure.FIGS. 2A-2Care schematic sectional views of a substrate at stages of the method100. To facilitate explanation of aspects of the present disclosure,FIGS. 2A-2Cwill be explained in conjunction withFIG. 1. It should be understood that the device structure depicted inFIGS. 2A-2Cis only an example and that the method100may be used to process any structure where it is desirable to achieve seam-free gapfill at low thermal budgets.

At operation110, a substrate201having one or more features formed therein is provided. The substrate201may be part of a semiconductor device, such as a semiconductor device200. In one implementation, the substrate201includes a high-k material selected from a group comprising, consisting of, or consisting essentially of hafnium dioxide (HfO2), zirconium dioxide (ZrO2), hafnium silicon oxide (HfSiO2), hafnium aluminum oxide (HfAlO), zirconium silicon oxide (ZrSiO2), tantalum dioxide (TaO2), aluminum oxide, aluminum doped hafnium dioxide, bismuth strontium titanium (BST), platinum zirconium titanium (PZT), and combinations thereof. In one implementation, the substrate201includes a channel material. In one implementation, the channel material is selected from a group comprising, consisting of, or consisting essentially of germanium, silicon-germanium, and other III-V semiconductor materials. In one implementation, the substrate201includes a high-k metal gate material. In one implementation, the high-k metal gate material is selected from a group comprising, consisting of, or consisting essentially of titanium nitride (TiN), tantalum (Ta), titanium aluminum nitride (TiAIN), titanium silicon nitride (TiSiN), and combinations thereof. In one implementation, the substrate201includes a dielectric material. In one implementation, the dielectric material is selected from a group comprising, consisting of, or consisting essentially of silicon nitride (SiN), silicon carbide (SiC), silicon oxides (e.g., SiO, SiO2, etc), and combinations thereof. During operation110, the semiconductor device200is positioned in a process chamber. The process chamber is, for example, a deposition chamber. The semiconductor device200includes one or more patterned features. The patterned features are sometimes referred to as placeholders, mandrels or cores and have specific linewidths and/or spacings based upon the photoresist material used to etch the patterned features.

In one implementation, the semiconductor device200includes mandrels2061,2062. . .206n(collectively206) formed on a first layer202. The first layer202may be the substrate201or a layer disposed on the substrate201. The first layer202has a surface204. The first layer202may contain a silicon (Si) containing material, a silicon dioxide (SiO2) containing material, or a silicon nitride (SiN) containing material. In one implementation, the mandrels2061,2062. . .206nare amorphous carbon (a-C) mandrels. In another implementation, the mandrels2061,2062. . .206nare amorphous silicon (a-Si) mandrels. As shown inFIG. 2A, the plurality of a-C mandrels206have a height of about 1 nanometer (nm) to about 100 nm from top surfaces2101,2102. . .210n(collectively210) of the plurality of a-C mandrels206to the surface204of the first layer202.

The semiconductor device200further includes a spacer layer212deposited over the plurality of a-C mandrels206and the first layer202. In one implementation, the spacer layer212is amorphous silicon (a-Si). In another implementation, the spacer layer212is silicon nitride (SiN). The spacer layer212may contain a nitrogen (N) containing material or an oxygen (O) containing material. The spacer layer212may be conformally deposited on the top surfaces210and sidewalls208of the plurality of a-C mandrels206to form gaps216between respective facing portions214of the spacer layer212on the sidewalls208of the plurality of a-C mandrels206. As shown inFIG. 2A, the gaps216have a width of about 1 nm to about 10 nm between the respective facing portions214. In one implementation, the gaps216have an aspect ratio that is greater than 5:1. Portions of the spacer layer212have been removed to expose top surfaces210of the plurality of a-C mandrels206and to expose the first layer202.

Referring toFIGS. 1 and 2B, the method100proceeds to operation120by performing a gapfill process to fill in the gaps216in the semiconductor device200. The gaps216are filled with a dielectric material220. In one implementation, the dielectric material220comprises a doped silicate glass. In one implementation, the doped silicate glass is selected from borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), and borosilicate glass (BSG). The dielectric material220is deposited by any suitable technique that complies with thermal budget targets, such as, for example, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), epitaxial deposition, spin-on coating, flowable CVD (FCVD), and conformal film deposition (CFD). The as-deposited dielectric material220typically contains defects (e.g., voids or seams)230in the dielectric material220.

In some implementations, the method100further includes applying a chemical mechanical polishing (CMP) process to remove excessive dielectric material and planarize the top surface of the dielectric material220. In some implementations, the dielectric material220is exposed to a curing process.

Referring toFIG. 1, the method100proceeds to operation130, where the semiconductor device200is exposed to a high-pressure annealing process. The annealing process of operation130is performed at a high process pressure, such as greater than 2 bar. The annealing process of operation130may assist densifying and repairing the vacancies in the dielectric material220, forming a dielectric layer240with the targeted film properties, as shown inFIG. 2C. The high-pressure annealing process of operation130may be performed in a batch mode or a single wafer mode. The high-pressure annealing process of operation130may be performed in a processing chamber, such as processing chamber300depicted inFIG. 3, or other suitable processing chambers, including those that process substrates one at a time. The high-pressure annealing process of operation130may be performed in the processing region or high-pressure region of the processing chamber.

The high-pressure annealing process performed at operation130maintains processing pressure at the high-pressure region in a vapor phase, for example in a dry vapor phase that has substantially no liquid droplets present. In one implementation, the high-pressure annealing process of operation130is a high-pressure steam annealing process. The processing pressure and temperature is controlled to densify the film structures, so as to repair the film defects, driving out impurities and increasing film density. In one implementation, the high-pressure region is pressurized to a pressure greater than atmosphere, for example greater than about 2 bar. In one implementation, the high-pressure region is pressurized to a pressure greater than atmosphere, for example up to 250 bar. In another implementation, the high-pressure region is pressurized to a pressure from about 5 bar to about 100 bar. In yet another implementation, the high-pressure region is pressurized to a pressure from about 5 bar to about 75 bar, such as a pressure from about 50 bar to about 75 bar. As the high-pressure may efficiently assist densifying the film structure at a relatively low processing temperature, such as less than 500 degrees Celsius, to reduce the likelihood of thermal cycle damage to the semiconductor device200.

During processing, the high-pressure region is maintained at a relatively low temperature, for example, a temperature less than 500 degrees Celsius, such as between about 150 degrees Celsius and about 400 degrees Celsius, by the heaters disposed within the processing chamber. Thus, a low thermal budget to the substrate may be obtained by utilizing the high-pressure annealing process along with low temperature regime.

It is believed that the high-pressure process may provide a driving force to drive out the dangling bonds in the dielectric material220, thus, repairing, reacting and saturating the dangling bonds in the dielectric material220during the annealing process. In one implementation, an oxygen-containing gas, such as O3gas, O2gas, H2O, H2O2, N2O, NO2, CO2, CO, dry steam, or other suitable gases may be supplied during the annealing process. In one implementation, the oxygen-containing gas comprises steam, for example, dry steam. In one implementation, the steam is formed from heated liquid water. In another implementation, the steam is formed from the reaction between hydrogen and oxygen. The oxygen elements from the oxygen-containing gas during the annealing process may be driven into the dielectric material220, altering the bonding structures and removing the atomic vacancies therein, thus, densifying and enhancing lattice structures of the dielectric material220to form a dielectric layer240which is substantially free from seams and voids. In some implementations, inert gas, such as Ar, N2, He, Kr and the like, may be supplied with the oxygen-containing gas. In one implementation, the oxygen-containing gas supplied in the oxygen-containing gas mixture is dry steam supplied at a pressure greater than 2 bar.

In one implementation, a process pressure is regulated at a pressure greater than 2 bar, such as between 5 bar and 100 bar, such as between 20 bar and about 80 bar, such as between about 25 bar and 75 bar, for example between about 50 bar and about 75 bar. The process temperature may be controlled at greater than 150 degrees Celsius but less than 500 degrees Celsius, such as between about 150 degrees Celsius and about 400 degrees Celsius, such as between about 180 degrees Celsius and about 350 degrees Celsius. In one implementation, after positioning the semiconductor device200in the high-pressure annealing chamber, both temperature and pressure are simultaneously ramped to the targeted annealing pressure and the targeted annealing temperature. In another implementation, after positioning the semiconductor device200in the high-pressure annealing chamber, the temperature is ramped to the targeted annealing temperature followed by ramping the pressure to the targeted annealing pressure. In yet another implementation, after positioning the semiconductor device200in the high-pressure annealing chamber, the pressure is ramped to the targeted annealing pressure followed by ramping the temperature to the targeted annealing temperature.

In another implementation, the semiconductor device200including the dielectric layer240is exposed to a dry annealing process (i.e., no steam). Not to be bound by theory, but it is believed that the boron in BPSG tends to form crystallites and that the dry anneal eliminates the crystallites. In one implementation, the dry annealing process is performed at a temperature less than 800 degrees Celsius. In one implementation, the dry annealing process is performed at a temperature less than 500 degrees Celsius. In one implementation, the dry annealing process is performed with a temperature in the range from about 150 degrees Celsius to about 400 degrees Celsius and with duration in the range from about one second to about 10 minutes. In one implementation, the dry anneal is performed in the same pressure ranges as the high-pressure anneal of operation130. In one implementation, the dry anneal is performed in an inert gas atmosphere. In one implementation, the inert gas atmosphere is a nitrogen gas atmosphere. In one implementation, the high-pressure steam anneal and the dry anneal are performed in the same chamber. In another implementation, the high-pressure steam anneal and the dry anneal are performed in separate chambers.

In one implementation, the dry annealing process is a spike annealing process. The spike annealing process has a short time duration and is applied to the dielectric layer240in the semiconductor device200to enhance the effect of the high-pressure annealing process. The spike annealing process may be a rapid thermal anneal (RTA), a laser anneal, and/or a flash lamp anneal. In one implementation, the spike annealing process is performed with a temperature in the range from about 150 degrees Celsius to about 400 degrees Celsius and with duration in the range from about one second to about 10 minutes.

After the annealing process, the dielectric layer240has a densified film structure, which provides a relatively robust film structure that provides an improved wet etching rate (compared to a porous film structure often having a high wet etching rate).

At the conclusion of method100, further processing may be performed thereafter to the pattern of the semiconductor device200.

FIG. 3is a schematic sectional view of the exemplary processing chamber300, which may be used to practice the method100described herein. Although the processing chamber300depicted inFIG. 3includes a batch of substrates that may be simultaneously processed in the processing chamber, it is noted that the processing chamber300may be configured to process a single substrate in each process as needed.

The processing chamber300may be configured to form the dielectric layer, such as the dielectric layer240depicted inFIG. 2, which will be described further in detail below, under a high-pressure control, such as greater than 2 bar.

The processing chamber300has a cassette330disposed in an internal volume350for processing a plurality of substrates335. The processing chamber300has a chamber body310enclosing the internal volume350, and a lid311disposed on the chamber body310. One or more heaters312are disposed within the chamber body310. The heaters312, such as resistive heaters, are configured to heat the chamber body310. Power to the heaters312is supplied by a power source305and controlled by the controller380. A shell320is disposed within the internal volume350. An insulating liner316is disposed in the internal volume350surrounding the shell320. The insulating liner316prevents heat transfer between chamber body310and the shell320.

The cassette330couples to a shaft374which extends through an opening354in the chamber body310. The cassette330is moveably disposed within the internal volume350by an actuator370coupled to the shaft374. The cassette330facilitates transfer of substrates335between a loading position and a processing position. Substrates335are transferred into and out of the internal volume350thorough a loading port345formed in the chamber body310. The shell320couples to the lid340of the cassette330when the cassette330is in the processing position and defines a processing region wherein the substrates335are annealed at an elevated pressure and an elevated temperature.

During processing, a processing fluid, such as an oxygen-containing gas (e.g., steam), is flowed into the processing region through an inlet port352. The inlet port352is in fluid communication with the substrates335through a plurality of apertures in the cassette330. Heaters327, disposed within the processing region, are configured heat the processing region and the substrates335therein. The pressure and temperature within the processing region are raised in order to anneal the substrates335therein. The processing fluid is evacuated from the processing region through an outlet port356.

In one implementation, the controller380is coupled to a plurality of sensors314, such as temperature sensors or pressure sensors. The sensors314provide signals to the controller to indicate the conditions within the internal volume350. The controller380controls the flow of the processing fluid as well as the power supplied to the heaters312,327to process the substrates335in a targeted manner.

In operation, a processing fluid is introduced through the inlet port352. The processing fluid is removed through the outlet port356using a pump (not shown). During processing of the substrates335an environment of the pressure region is maintained at a temperature and pressure that maintains the processing fluid within the processing region in a vapor phase. Such pressure and temperature is selected based on the composition of the processing fluid. In the case of steam, the temperature and pressure is held at a condition that maintains the steam in a dry steam state. In one example, the processing region is pressurized to a pressure greater than atmosphere, for example greater than about 2 bar. In another example, the processing region is pressurized to a pressure greater than atmosphere, for example up to about 250 bar. In another implementation, the processing region is pressurized to a pressure from about 5 bar to about 100 bar. In yet another implementation, the processing region is pressurized to a pressure from about 5 bar to about 75 bar, such as a pressure from about 50 bar to about 75 bar. During processing, the processing region is also maintained at a high temperature, for example, a temperature exceeding 225 degrees Celsius (limited by the thermal budget of the substrates335disposed on the cassette330), such as between about 300 degrees Celsius and about 450 degrees Celsius, by the heaters312,327. Exposure to the processing fluid at a high-pressure while the substrates335are maintained at a high temperature causes reflow of the dielectric gapfill material to reduce the formation of seams in the dielectric gapfill material.

In some implementations, the method described herein results in a high quality doped silicon glass film that functions as a gapfill material that is substantially free of seams or voids. Conventional anneal methods, such as furnace annealing, result in poor distribution of the oxygen through the oxide layer. The oxygen only penetrates a shallow area near the surface of the layer in such conventional methods. The inventors of the disclosure have found that the use of a high-pressure anneal in the presence of an oxidizer promotes conformal oxidation of the layer. That is, the layer is oxidized in a substantially uniform manner across the entirety of the layer thereby increasing uniformity of the distribution of oxygen throughout the layer. Further, the uniformity of the densification of the oxide layer is increased by the methods described herein. The uniform densification also typically results in improved etch selectivity. Some implementations of the present disclosure use a steam anneal performed at high pressures (e.g., greater than one atmosphere) to enable reflow of doped silicate glass films at a temperature less than 500 degrees Celsius. In some implementations, doped silicate glass is exposed to a multi-step anneal process. In some implementations, the multi-step anneal process includes—(1) exposing the doped silicate glass to a steam anneal at high pressure to enable reflow; and the (2) exposing the doped silicate glass to a dry environment anneal to eliminate any remaining moisture. The ability to use doped silicate glass films for gapfill at low thermal budgets provides a new material scheme for multi-color patterning to enable self-alignment.

When introducing elements of the present disclosure or exemplary aspects or implementation(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.

The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.