Semiconductor constructions, and methods of forming dielectric materials

Some embodiments include methods of forming dielectric materials associated with semiconductor constructions. A semiconductor substrate surface having two different compositions may be exposed to a first silanol, then to organoaluminum to form a monolayer, and finally to a second silanol to form a dielectric material containing aluminum from the organoaluminum together with silicon and oxygen from the second silanol. Alternatively, or additionally, an organoaluminum monolayer may be formed across a semiconductor substrate, and then exposed to silanol within a deposition chamber, with the silanol being provided in two doses. Initially, a first dose of the silanol is injected the chamber, and then the first dose is flushed from the chamber to remove substantially all unreacted silanol from within the chamber. Subsequently, the second dose of silanol is injected into the chamber. Some embodiments include semiconductor constructions.

TECHNICAL FIELD

The technical field pertains to semiconductor constructions, and to methods of forming dielectric materials associated with semiconductor constructions.

BACKGROUND

Electrically insulative materials (in other words, dielectric materials) are widely used in semiconductor fabrication to electrically isolate various electrical components from one another. Devices that extend into a semiconductor substrate may be electrically isolated by trenched isolation regions formed within the substrate between the components. In such technique, trenches are etched into a semiconductor substrate (such as a silicon substrate); and the trenches are subsequently filled with dielectric material (such as silicon dioxide).

Various methods have been developed for depositing dielectric materials across semiconductor substrates. Such methods include chemical vapor deposition (CVD) processes and atomic layer deposition (ALD) processes. ALD processes are generally processes in which precursor materials react at a surface, rather than in a vapor phase above the surface. In contrast, CVD processes are generally processes in which precursor materials react in a vapor phase above the surface to form the deposit that ultimately accumulates on the surface. ALD processes will generally be characterized by successive, controlled formation of monolayers across a substrate surface, with the monolayers building up to form the desired deposit to a desired thickness. CVD process will not comprise controlled formation of monolayers, and instead will form a thick bulk deposit across a substrate surface in a single deposition step.

An advantage of CVD is that it is relatively rapid, and accordingly may be utilized to achieve high throughput of wafers through a fabrication process. A disadvantage of CVD is that it tends to lead to relatively poor uniformity of deposition across a substrate. In contrast, an advantage of ALD is that it may accomplish relatively good uniformity of deposition across a substrate, and a disadvantage of some ALD processes is that they tend to be slow and accordingly associated with low throughput of wafers through a fabrication process. It is desired to develop processes having the good uniformity associated with ALD, while also allowing relatively high throughput of wafers through a fabrication process.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Embodiments may include improvements on so-called pulse deposition layer (PDL) methods of forming dielectric material. A PDL method may comprise formation of a monolayer of organoaluminum material across a substrate, followed by exposure of the monolayer to silanol to form a dielectric material. A problem with conventional PDL methodology is that dielectric materials deposited by such methodology may lack desired uniformity across a semiconductor wafer.

Two embodiments are shown and described with reference to the accompanying drawings. The embodiments may be utilized separately or in combination. The embodiments may lead to improved uniformity of a deposited dielectric material relative to conventional PDL methodology. One embodiment is described with reference toFIGS. 1-7, and includes pretreatment of a surface of a semiconductor substrate with silanol prior to formation of the monolayer of organoaluminum material. The other embodiment is described with reference toFIGS. 8-14, and includes utilization of two separate doses of silanol after formation of the monolayer.

Referring toFIG. 1, such illustrates a semiconductor construction10. Specifically, a pair of fragments6and8of the construction are shown. The semiconductor construction comprises a base12. The base may comprise, consist essentially of, or consist of, for example, monocrystalline silicon lightly-doped with background p-type dopant. To aid in interpretation of the claims that follow, the terms “semiconductive substrate” and “semiconductor substrate” are defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above.

The fragment6comprises a material16over base12, and comprises an upper surface17corresponding to the upper surface of material16. Material16may comprise any of numerous compositions or combinations of compositions; and may, for example, comprise, consist essentially of, or consist of silicon nitride, silicon dioxide, or silicon oxynitride. Accordingly, upper surface17may comprise, consist essentially of, or consist of silicon nitride, silicon dioxide, or silicon oxynitride.

The fragment8comprises an upper surface15corresponding to the composition of base12. Accordingly, upper surface15may comprise, consist essentially of, or consist of monocrystalline silicon, either alone, or with dopant therein.

An opening18is shown extending into base12of fragment8. The opening may be formed to any desired depth, and may correspond to a trench within which dielectric material is to be deposited to form a trenched isolation region.

Construction10may be considered to comprise an upper topography that extends across surfaces15and17. Such topography comprises two different exposed compositions, with one of the compositions corresponding to the composition of surface15and the other corresponding to the composition of surface17. It is to be understood that the diagrammatic illustration ofFIG. 1illustrates one of numerous constructions containing an upper topography with two different exposed surface compositions. For instance, native oxide (not shown) may extend across exposed surfaces of base material12, and construction10will still have a different surface composition across fragment8than across fragment6if upper surface17of fragment6comprises a composition other than silicon dioxide. Further, although only two different exposed surface compositions are illustrated, it is to be understood that the construction may have more than two different exposed surface compositions. For instance, three or more compositions selected from the group consisting of photoresist, silicon nitride, silicon oxynitride, silicon dioxide, doped silicon and undoped silicon may be exposed across construction10. The doped and/or undoped silicon may be amorphous, polycrystalline and/or monocrystalline.

Referring toFIG. 2, surfaces15and17of construction10are exposed to silanol20. The silanol may be a single silanol composition or a combination of silanol compositions; and may, for example, include one or more of alkoxysilanols, alkoxyalkylsilanols, alkoxysilanediols, and the like. Example silanols include tris(alkoxy)silanol compounds, such as, for example, tris(tert-butoxy)silanol (TBOS) and tris(tert-pentoxy)silanol (TPOS); and include diols, such as, for example, bis(tert-alkoxy)silanediol.

Construction10may be placed within a deposition chamber and exposed to a dose of silanol20for a time of less than or equal to about 60 seconds, (such as, for a time of less than or equal to about one second). The exposure to the dose of silanol may be conducted by initially providing a desired dose within the deposition chamber, and then holding the chamber static for a desired time (a so-called soak time). If the exposure is less than one second, the dose may be flowed through the chamber so that there is effectively no soak time.

An example chamber is diagrammatically illustrated inFIG. 15as part of a deposition apparatus200. Specifically, the apparatus200is shown to comprise a sidewall202which surrounds a deposition chamber204. A pair of openings206and208are shown extending through the sidewall. The openings correspond to an inlet and an outlet, respectively, and flow of material through the inlet and outlet is diagrammatically illustrated by arrows207and209.

A valve210is diagrammatically illustrated across opening206, and another valve212is diagrammatically illustrated across opening208.

The deposition apparatus200comprises a substrate holder214. A substrate construction10is diagrammatically illustrated as being supported by holder214.

In operation, a desired material is flowed into chamber200to expose an upper surface of construction10to such material. Valves210and212are utilized to control flow of material into and out of the chamber so that construction10is exposed to a desired composition and concentration of material for a desired time. As discussed above, the silanol pretreatment may or may not comprise a soak. If the pretreatment is conducted with a soak, an initial dose of silanol is flowed into chamber204; then the inlet valve210is closed and the chamber held static for the soak time; and finally, after the desired soak time valves210and212are adjusted to purge any unreacted silanol from the chamber. The purging may be conducted utilizing a pump to withdraw unreacted silanol from the chamber and/or utilizing a purge gas to flush unreacted silanol from the chamber.

The chamber may, for example, have an internal volume of 1 liter, and the dose of silanol may be from about 5 micromoles to about 300 micromoles; and may, for example, be about 20 micromoles (for instance, about 22 micromoles). The dose may comprise one or more silanols. In some applications, the silanol of the dose may comprise, consist essentially of, or consist of one or both of TPOS and TBOS.

The silanol dose may be pulsed into the deposition chamber in an inert carrier gas (e.g., N2, He, Ar, etc.) at a silanol flow rate of about 100-500 standard cubic centimeters per minute (sccm), (such as, for example, about 300 sccm), a reaction chamber temperature of from about 90° C. to about 350° C., (such as, for example, from about 200° C. to about 320° C., and may be about 230° C.); and a chamber pressure of from about 0.5 Torr to about 10 Torr, (such as, for example, about 1 Torr). The silanol may be delivered into the reaction chamber by known methods, including, for example, by vaporizing the silanol in an ampoule or bubbler at a temperature of from about 70° C. to about 100° C., (such as, for example, about 80° C.); and introducing the vaporized silanol in combination with a carrier gas into the chamber.

After the silanol pretreatment of exposed surfaces of construction10, the silanol is evacuated from the deposition chamber. Subsequently, as shown inFIG. 3, construction10is exposed to at least one organoaluminum composition (or material)24. The organoaluminum composition may be any suitable organic compound that will allow the aluminum to deposit under ALD conditions and chemisorb to the surface of the substrate with organic groups (e.g., methyl groups) available for oxidation. Example organoaluminum compositions include aluminum alkyls such as trimethylaluminum (TMA), triethylaluminum, triisobutylaluminum, and the like; alkylaluminum alkoxides such as triethyl(tri-sec-butoxy)dialuminum (TETBAL), and the like; and aluminum amides such as Al2(NEt2)6, Al2(NEtMe)6, Al2(NMe2)6, and the like. The ALD deposition may be referred to as a deposition process comprising conditions suitable for formation of an atomic layer.

The exposure to the organoaluminum composition forms an organoaluminum-comprising layer26across surfaces15and17, as shown inFIG. 4. Such organoaluminum-comprising layer may be a monolayer; may comprise, consist essentially of, or consist of carbon, aluminum and hydrogen; and may further include one or both of nitrogen and oxygen.

A conventional ALD process may be used during theFIG. 3exposure to form the monolayer26ofFIG. 4. Such ALD process may be conducted in the chamber200ofFIG. 15, and may utilize delivery of an organoaluminum composition from a vaporization chamber (not shown) to the deposition chamber. The organoaluminum composition may be vaporized by known methods. For example, a liquid form of the organoaluminum composition may be placed in a bubbler and heated (if necessary) to its vaporization temperature, and the vaporized organoaluminum composition may then be either directly introduced into the deposition chamber, or transported by a carrier gas (e.g., Ar, He, etc.).

Example conditions for forming the organoaluminum-comprising layer26may include a deposition chamber temperature of from about 90° C. to about 350° C., (such as, for example, from about 200° C. to about 320° C., such as about 230° C.); and a chamber pressure of from about 0.5 Torr to about 10 Torr, (such as, for example, about 1 Torr). The cycle duration (pulsing) of the organoaluminum precursor (e.g., trimethylaluminum) may be from about 1 second to about 5 seconds (such as, for example, about 1 second), to deposit a monolayer of organoaluminum substance onto the surfaces of the construction10.

After formation of layer26, unreacted organoaluminum composition is purged from the deposition chamber. The purging may be conducted with an inert gas such as nitrogen (N2), argon (Ar), helium (He), neon (Ne), Krypton (Kr), xenon (Xe), and the like, at a flow rate of from about 500 sccm to about 1,000 sccm, for a time of from about 1 second to about 30 seconds, (such as, for example, a time of about 10 seconds).

Referring next toFIGS. 5 and 6, the organoaluminum-comprising layer26is exposed to at least one silanol30to form a dielectric material32. The shown dielectric material comprises an upper portion34and a lower portion36. The lower portion36may comprise aluminum from the organoaluminum-comprising layer together with silicon and oxygen from the silanol; and the upper portion may consist essentially of, or consist of silicon and oxygen from the silanol. The two portions34and36may result if there is enough exposure to silanol to cause dielectric material32to be formed much thicker than the original organoaluminum-comprising layer36, and if aluminum from layer26(FIG. 5) does not uniformly distribute throughout dielectric32. Alternatively, dielectric32may be formed to substantially homogeneously comprise a mixture of aluminum from layer26together with silicon and oxygen from the silanol.

The exposure to the silanol ofFIG. 5for dielectric material growth may comprise processing similar to that discussed above relative to the pretreatment ofFIG. 2, or may comprise a higher dose than the pretreatment for a longer soak time. The silanol exposure ofFIG. 5may utilize silanols identical to those discussed above for the pretreatment ofFIG. 2. The silanol utilized for the pretreatment may be referred to as a first silanol, and that utilized for the dielectric material growth may be referred to as a second silanol, to distinguish the silanol utilized at one processing stage from that utilized in another processing stage. The first and second silanols may be identical to one another, or different.

The silanol pretreatment ofFIG. 2may improve uniformity of dielectric material growth (in other words, growth of the material32ofFIG. 6) relative to the uniformity which would occur in the absence of such pretreatment. For instance, it is found that if identical constructions are compared after growth of dielectric material32, with one of the constructions being subjected to the silanol pretreatment and the other not, the construction that received the silanol pretreatment has a uniformity parameter (as measured as range/mean across a semiconductor wafer times 100) of less than or equal to about 4 percent (for instance, 3.7 percent), whereas the construction that did not receive the silanol pretreatment has a uniformity parameter of 37.2 percent (with the tested wafers being 200 millimeter wafers). In other words, the silanol pretreatment has provided in order of magnitude improvement in uniformity of the deposited dielectric material.

A possible mechanism by which the silanol pretreatment may improve the uniformity of the deposited dielectric material is that the silanol pretreatment provides a layer of OH groups across the various surface compositions of the construction. Such OH groups may react with organoaluminum materials to form a uniform monolayer across the various surfaces; whereas, without the pretreatment, there would be less uniformity of the number of OH groups across the various surface compositions, which would lead to less uniformity of the organoaluminum monolayer. This mechanism is provided to assist the reader in understanding the subject matter described herein, but is not to limit the claims that follow except to the extent, if any, that the mechanism is expressly recited in the claims.

Dielectric material32may be formed to a thickness of, for example, from about 500 angstroms to about 1000 angstroms, and then the growth of the dielectric material will substantially cease. If it is desired to form dielectric material32to be thicker, the processing described above may be repeated multiple times to form stacks of dielectric material32as shown inFIG. 7. However, once that a substrate is uniformly coated with dielectric material32, the silanol pretreatment may be omitted during formation of subsequent sections of the stacks of dielectric material32. Thus, some applications may include processing throughFIG. 2, followed by one or more iterations of the processing ofFIGS. 3-6to form a dielectric material stack to a desired thickness.

Referring next toFIG. 8, such illustrates a fragment of a semiconductor construction50at a preliminary processing stage of another embodiment. The illustrated fragment of construction50is identical to the fragment8of construction10discussed above, and accordingly comprises base12having opening18extending therein.

Construction50is exposed to at least one organoaluminum composition24, under processing similar to that discussed above regardingFIG. 3. The difference between construction50ofFIG. 8and the construction10at the processing stage ofFIG. 3, is that construction50may not have been exposed to silanol precursor in some applications (of course, in other applications construction50will have been exposed to silanol precursor prior to the processing stage ofFIG. 8).

FIG. 9shows construction50after the exposure to the organoaluminum composition to form the organoaluminum-comprising layer26. The processing ofFIGS. 8 and 9may occur in the reaction chamber200described with reference toFIG. 15, and after such processing, unreacted organoaluminum composition may be flushed from the chamber.

FIGS. 10-13illustrate exposure to silanol30and formation of dielectric32utilizing alternative processing to that discussed above with reference toFIGS. 5 and 6. Specifically, the processing described with reference toFIGS. 5 and 6utilized a single large dose of silanol to form the dielectric. In contrast, the processing ofFIGS. 10-13utilizes two separate doses of silanol to form the dielectric.

Referring toFIG. 10, a first dose of silanol30is provided to initiate formation of dielectric32. The first dose is shown converting an upper portion of organoaluminum-comprising layer26to the dielectric36comprising aluminum, silicon and oxygen. A boundary between dielectric36and unconverted portions of layer26is diagrammatically illustrated with a dashed line53. The diagram ofFIG. 10is provided to assist the reader in understanding subject matter presented herein. It is to be understood that the first dose may only convert a portion of layer26to the dielectric36(as shown), or may convert an entirety of layer26to dielectric36(including applications in which the first dose is sufficient to form a portion of the dielectric34discussed above as consisting essentially of, or consisting of silicon and oxygen).

The first dose of silanol30may be provided utilizing processing conditions similar to those discussed above regardingFIG. 5. The first dose may be a low amount of silanol provided for a short duration within the deposition chamber. For instance, the first dose may comprise five micromoles of silanol, provided in the deposition chamber volume discussed previously for less than one second (in other words, provided with little to no soak time). However, the quantity of silanol utilized for the first dose, and the duration of exposure utilized for the first dose, may vary to accommodate differing applications. In some applications, the first dose may be conducted with a silanol amount of from about 5 micromoles to about 300 micromoles in the chamber volume discussed previously, with an exposure duration of less than or equal to about 60 seconds.

The chamber is flushed (purged) to remove substantially all unreacted silanol of the first dose, leaving the construction ofFIG. 11remaining within the chamber. The term “substantially all” is utilized to indicate that the vast majority of the unreacted silanol is removed from the chamber, which may leave no detectable unreacted silanol within the chamber; which includes, but is not limited to, applications in which the entirety of the unreacted silanol is removed from the chamber. Subsequently, a second dose of silanol30is provided within the chamber as shown inFIG. 12to grow the remainder of dielectric material32. The second dose is then purged from the chamber to leave the construction ofFIG. 13.

Although the second dose is shown using the same silanol30as was used for the first dose, it is to be understood that the silanol of the second dose may have one or more silanol compounds that differ from the silanol composition of the first dose, and in some cases may have no silanol compounds in common with the silanol composition of the first dose.

The second dose may utilize a larger amount of silanol for a longer exposure duration than the first dose. For instance, the second dose may utilize 20 micromoles of silanol in the deposition chamber volume discussed above, with a 10 second soak time. The quantity of silanol utilized for the second dose, and the duration of exposure utilized for the second dose, may vary to accommodate differing applications. In some applications the second dose may be conducted with a silanol amount of from about 5 micromoles to about 300 micromoles (such as, for example, from about 5 micromoles to about 100 micromoles) in the chamber volume discussed previously, with an exposure duration of less than or equal to about 120 seconds, (such as, for example, less than or equal to about 60 seconds, and in some applications less than or equal to about 10 seconds).

The splitting of the silanol exposure amongst two separate doses may improve uniformity of dielectric material growth. For instance, it is found that if identical constructions are compared after growth of dielectric material32, with one of the constructions receiving the silanol split amongst two separate dose and the other receiving the silanol as one large dose, the construction that received the silanol as two separate doses has a uniformity parameter (as measured as range/mean across a semiconductor wafer times 100) of 3.1 percent, whereas the construction that received the silanol as a single large dose has a uniformity parameter of 7.9 percent (with the tested wafers being 200 millimeter wafers). In other words, the silanol pretreatment has provided about a 60% improvement in uniformity of the deposited dielectric material.

A possible mechanism for the improvement achieved by splitting the silanol exposure into two separate doses is that the purging of the deposition chamber after the first dose removes reaction byproducts that otherwise interfere with the overall growth of dielectric material32. This mechanism is provided to assist the reader in understanding subject matter presented herein, and is not to limit the claims that follow except to the extent, if any, that the mechanism is expressly recited in the claims.

Multiple iterations of the processing ofFIGS. 9-13may be conducted to form a stack of dielectric material32over base12as shown inFIG. 14.

The processing ofFIGS. 8-13may be combined with that ofFIGS. 1-7. Specifically, a silanol pretreatment may be conducted before formation of an organoaluminum-comprising layer, and subsequently aluminum of the organoaluminum may be incorporated into a dielectric formed with silanol provided in two separate steps (with the term “two separate steps” indicating that the silanol is provided in two separate doses which are within a reaction chamber at separate and non-overlapping times relative to one another).

Dielectric materials described above may be utilized for electrically isolating circuitry of semiconductor constructions. The semiconductor constructions having such dielectric material incorporated therein may be utilized in electronic systems, including, for example, computers, cameras, cars, phones, medical instrumentation, etc.