Patent ID: 12216400

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As previously noted, a directed self-assembly process uses block copolymers. Block copolymer mixtures are blended by vendors and shipped pre-packaged to the manufacturing facility in discrete bottles. A disadvantage of such a typical directed self-assembly process is that vendors of pre-packaged block copolymers are generally not aware of the specific process requirements for a given process flow and therefore would not be able to meet the specific composition process window required at the manufacturing facility, e.g., to meet the critical dimension targets for the features. A high volume manufacture of IC's may require multiple packages of the same block copolymer mixture. However, due to quality control issues, multiple bottles of the same block copolymer mixture, especially from different batches, may have inconsistent molecular weights. Hence, different packages of the same block copolymer mixture from the vendor may have differing compositions of the block copolymers and therefore produce features having different critical dimensions and pitches. As an example, in some technologies, a 10% batch-to-batch variability of the molecular weight of a block copolymer mixture can change the critical dimension of a device element by more than 6%. Such large deviations can potentially cause a process hold, where the production line is stopped until the feature sizes are brought back within the process window. Also, reordering pre-packaged block copolymer mixtures is costly because of the downtime of the fabrication facility for the time taken to receive the new bottle.

Another disadvantage of directed self-assembly is that every feature having a different critical dimension uses a separate block copolymer mixture. This is costly and time consuming if multiple levels or features are to be fabricated with a directed self-assembly process in a traditional semiconductor fabrication process. This is because for each feature that has to be patterned at a different feature size, a different composition of the block copolymer is to be used, which has to be delivered to the manufacturing facility. This can cause a significant bottleneck and increase costs associated with managing multiple bottles of pre-packaged block copolymer mixtures. For example, using multiple prepackaged bottles can get expensive due to the complexities associated with purchasing, scheduling, storing, and tool requirements associated with using different bottles.

Another disadvantage of directed self-assembly is that a pre-packaged block copolymer mixture has a single film thickness which can result in an uneven fill pattern across the substrate when the mixture is applied. In other words, each pre-packaged block copolymer mixture has a predetermined film thickness that it is able to achieve. Therefore, if a pre-packaged block copolymer mixture has a film thickness less than a target thickness, a pattern of device elements will not be properly filled. Thus, even for features having the same critical dimension, the same bottles may not be used because of the differences in thickness of the base layer being patterned.

Embodiments of the present invention advantageously avoid the above issues by forming the block copolymer mixtures within the fabrication facility which allows for consistency between batches, improved control over the feature metrics such as critical dimension, pitch, microphase separation, surface roughness, local critical dimension uniformity, and control of the pattern fill density to ensure a uniform coating across a substrate. This disclosure describes embodiments of methods of blending block copolymer mixtures in an inline mixer within a processing tool such as a coating tool within a fabrication facility that enables cost effective manufacturing of ICs with a directed self-assembly process.

A coating tool within a fabrication facility is illustrated inFIG.1andFIG.2, in accordance with an embodiment of the invention. Several example embodiments of methods of forming a semiconductor device with the coating tools are described in greater detail inFIGS.3-7.

FIG.1illustrates a block copolymer coating tool in accordance with an embodiment of the present application.

As illustrated inFIG.1, the block copolymer coating tool includes a first mixer apparatus100and a processing tool124in which a semiconductor substrate120is processed. The processing tool124comprises a processing chamber122and a substrate holder121configured to support the semiconductor substrate120during processing. A blended block copolymer mixture is coated onto a major surface of the semiconductor substrate120by injecting the blended block copolymer mixture from the first mixer apparatus100through a nozzle118of the processing tool124. For example, the nozzle118may be a flat flan nozzle, solid stream nozzle, or any other nozzle known to a person having ordinary skill in the art.

The substrate holder121may be configured to be rotated during the coating process. The processing chamber122includes outlets for any excess fluid and may also be connected to a pressure system to maintain a target pressure within the processing chamber122in certain embodiments. The processing chamber122may also include gas inlets such as for pumping inert gases into the processing chamber122for certain applications.

Referring toFIG.1, the first mixer apparatus100includes a first supply tank102and a second supply tank104coupled to a mixer114comprising a mixing chamber112. Although only two sources are illustrated as being mixed, in various embodiments, more than two sources of fluids may be mixed in the mixer114. The first supply tank102and the second supply tank104each hold a first liquid and a second liquid, respectively. In various embodiments, the first supply tank102and the second supply tank104are made of ceramics, glass, stainless steel or any other material depending upon the corrosive properties of the first and second liquids being used.

In various embodiments, the first liquid comprises a first block copolymer comprising a first homopolymer (-A-A- . . . A-A-) and a second homopolymer (-B-B- . . . B-B-). Accordingly, the first homopolymer is a polymer of a first monomer (A) while the second homopolymer is a polymer of a second monomer (B). A block copolymer ((-A-B-)-(-A-B-)- . . . (-A-B-)-(-A-B-)-) is formed when the first homopolymer is mixed with the second homopolymer (B). Examples of homopolymers include methyl-methacrylate, styrene, dimethylsiloxane, ethylene oxide, butadiene, vinylpyridine, isoprene, lactic acid, and others.

In various embodiments, the first homopolymer has a first mole fraction in the first liquid. The second liquid comprises a second block copolymer comprising the first homopolymer and the second homopolymer. The first homopolymer has a second mole fraction in the second liquid. Thus, while both the first liquid and the second liquid have the same polymers, the first mole fraction is different than the second mole fraction.

In one or more embodiments, the first homopolymer is a polystyrene block comprising repeating styrene units and the second homopolymer is a poly methyl-methacrylate block comprising repeating methyl-methacrylate units. The first homopolymer together with the second homopolymer form poly(styrene-b-methyl-methacrylate), i.e., repeating styrene-b-methyl-methacrylate units, which is a block copolymer. Therefore the first liquid and the second liquid both comprise of poly(styrene-b-methylmethacrylate) with different molecular weights. The first liquid and the second liquid are described herein for example only. A person having ordinary skill in the art may use other types of liquids as well.

In various embodiments, the first mole fraction may range from 10% to 90% in the first liquid and the second mole fraction may range from 10% to 90% in the second liquid so long as the first mole fraction and the second mole fraction are different.

In various embodiments, the first mixer apparatus100may be gravity driven with few intermediate components or may comprise a system of pumps and valves for control of fluid flow. Accordingly, in certain embodiments, the first mixer apparatus100optionally includes a first pump106a, a second pump106b, and a third pump106c, a first shutoff valve108a, a second shutoff valve108b, and a third shutoff valve108c, a first flowmeter110a, a second flowmeter110b, and a third flowmeter110c.

The first supply tank102and the second supply tank104are both connected to a first pump106aand a second pump106b. The first pump106aand the second pump106bare respectively connected to a first shutoff valve108aand a second shutoff valve108bthat are further coupled to the mixer114. The mixer114is connected to the processing tool124via an optional third pump106cconnected to a third shutoff valve108cand a third flowmeter110c.

As illustrated inFIG.1, the mixer114may be disposed within the mixing chamber112. As one example, the mixer114may be designed as described in Application Ser. No. 62/839,917, filed on Apr. 29, 2019, which is incorporated herein by reference. In certain embodiments, the mixer114may be a planetary mixer, a static mixer, or any other mixer known to a person having ordinary skill in the art that can blend liquid mixtures.

The first mixer apparatus100may further include an electronic flow control system115, e.g., to control the various aspects of the fluid flow. The electronic flow control system115comprises a controller116and various memory, input/output devices, analog to digital converters, and other hardware and software as known to a person with ordinary skill in the art. For example, the controller may comprise a processor, microprocessor, or any other type of controller known in the art. In addition, the electronic flow control system115includes sensors such as flow sensors, temperature sensors, and others.

The electronic flow control system115is connected to the first pump106a, the second pump106b, the third pump106c, the first shutoff valve108a, the second shutoff valve108b, the third shutoff valve108c, the first flowmeter110a, the second flowmeter110b, the third flowmeter110c, the mixer112as well as other components such as the processing tool. More specifically, measurement data from the first flowmeter110a, the second flowmeter110b, the third flowmeter110cmay be received at the electronic flow control system115while control signals generated at the controller116may be sent to the first pump106a, the second pump106b, the third pump106c, the first shutoff valve108a, the second shutoff valve108b, the third shutoff valve108c.

The electronic flow control system115may receive measurement or metrology data from sensors103and process information including process recipe/metrics105such as a target process window. Sensors103may include various types of sensors including, but not limited to optical sensors (such as cameras, lasers, light, reflectometer, spectrometers, etc.), capacitive sensors, ultrasonic sensors, gas sensors, temperature sensors to monitor liquid temperature, or other sensors that may monitor the blending process as well as the first liquid, the second liquid, and the blended first mixture. The electronic flow control system115may receive additional data inputted by the user including, but not limited to, the target volumes of a first liquid in the first supply tank102, a second liquid in the second supply tank104, a first mixture, and a required mixing time. In one example embodiment, a mass spectrometer may be used to determine the composition of the first liquid and the second liquid periodically. In one example embodiment, one or more optical sensors may be used to determine opacity of the first and second liquids periodically that can help determine the validity of the composition.

Based on the data from the various sensors103and process recipe/metrics105, the controller116will generate control signals to activate the first pump106aand the second pump106band deactivate the first shutoff valve108aand the second shutoff valve108bto dispense the first liquid and the second liquid into the mixer114. The first pump106a, the second pump106b, and the third pump106cmay comprise of any centrifugal pump or any positive displacement pumps that are able to pump liquid block copolymers as known to a person having ordinary skill in the art. The first shutoff valve108a, the second shutoff valve108b, and the third shutoff valve108cmay comprise of an electromotive diaphragm valve, an electromotive angle seat valve, or any other valve known to a person having ordinary skill in the art.

As the first and second liquids flow from the first supply tank102and the second supply tank104, the controller116constantly or periodically monitors the first flowmeter110aand the second flowmeter110bto track the volume of each liquid dispensed into the mixer114. For example, the first flowmeter110a, the second flowmeter110b, and the third flowmeter110cmay comprise of a positive displacement flowmeter that can directly provide the volume of a liquid dispensed with no additional calculation required or any other flowmeter known to a person having ordinary skill in the art.

Once the controller116determines, based on data provided by the first flowmeter110aand the various sensors103and process recipe/metrics105, that the target volume of the first liquid has been dispensed, the controller116generates control signals to activate the first shutoff valve108aand turn off the first pump106a. Similarly, when the controller116determines, based on data provided by the second flowmeter110band the various sensors103and process recipe/metrics105, that the target volume of the second liquid has been dispensed the controller116(CTLR) generates control signals to activate the second shutoff valve108band turn off the second pump106b.

After the first and second liquids are dispensed into mixer114, controller116will generate control signals to turn on mixer114for a duration based on the data received, and the mixer114blends the first liquid and the second liquid to form a first mixture.

In various embodiments, the mixer114may include a holding tank in which the blended liquids i.e., first mixture, are stored. However, in certain embodiments, the first mixture may be directly injected into the nozzle118of the processing tool without any separate holding tanks. In certain embodiments, the nozzle118and the holding tank may be integrated together, for example, in a plenum to the processing chamber122.

After the mixing, the controller116generates control signals to activate the optional third pump106cand deactivate the third shutoff valve108cso as to inject the first mixture into the nozzle118and coat the semiconductor substrate120with the first mixture within the process chamber122.

In an alternative embodiment in order to generate a more uniform fill density across the semiconductor substrate, using the method above, the second liquid may comprise of a solvent. In certain embodiments, the solvent may be added to improve metrics such as surface roughness and other features. In various embodiments, the solvent may be propylene glycol monomethyl ether acetate, toluene, or any other solvent known to mix with block copolymer mixtures in the art. In other embodiments, the solvent may be added from a third supply tank in addition to the second liquid comprising the second block copolymer from the second supply tank104.

In another alternative embodiment, the second liquid may comprise of essentially the first homopolymer or essentially the second homopolymer. In such embodiments, the first homopolymer or the second homopolymer may help to fine tune a parameter such as critical dimension or pitch of the feature to be patterned.

FIG.2illustrates a block copolymer coating tool in accordance with an embodiment of the present application.

As illustrated inFIG.2, the coating tool includes a second mixer apparatus200and a processing tool124in which a semiconductor substrate120is processed. The second mixer apparatus200may include any number of supply containers ranging from 1, 2, 3, . . . N poured into a mixer114to form a first mixture of block copolymers that is coated onto the semiconductor substrate120through a nozzle118. The first supply container 1 is configured to hold a first liquid, the second supply container 2 is configured to hold a second liquid, and correspondingly the nth supply container N is configured to hold the nth liquid. For example, the supply containers may be made out of ceramics, glass, stainless steel or any other material known by one with ordinary skill in the art based of the corrosive properties of the liquids.

In various embodiments, the first mixture includes a first liquid held in the first supply container 1 and a second liquid held in the second supply container 2. The first liquid held in the first supply container 1 as described above may be a first homopolymer and a second homopolymer with the first homopolymer having a first mole fraction in the first liquid. The second liquid held in the second supply container 2 as described above may be a first homopolymer and a second homopolymer with the first homopolymer having a second mole fraction in the second liquid.

The liquid valves from the multiple supply containers 1-N may be opened electronically or by the user so that the multiple liquids are blended in the mixer114as described above with respect toFIG.1to form the first mixture. In the same manner illustrated inFIG.1, the mixer114is connected to the processing tool124via the third pump106cthat is connected to the third shutoff valve108c, and the third flowmeter110c. The blended first mixture may be held in a holding tank either within the second mixer apparatus200or the processing tool124.

At the conclusion of mixing, the user deactivates the third shutoff valve108cand turns on the third pump106cso as to inject the first mixture into the nozzle118and coat the semiconductor substrate120with first mixture within the processing chamber122. As the first mixture exits mixer114, it flows through the third flowmeter110cand the user constantly or periodically monitors the volume readout of the third flowmeter110c. Then, once the third flowmeter110cdisplays that the desired volume of the first mixture has been dispensed, the user shuts off the third pump106cand activates the third shutoff valve108c.

In various embodiments, the semiconductor substrate120may undergo a curing process either in the processing tool124or in a different tool.

In other embodiments the first mixture may include a third liquid comprising essentially the first homopolymer, essentially the second homopolymer, or a solvent added from a third supply tank 3 in addition to the first liquid and the second liquid. The first homopolymer, the second homopolymer, and solvent are not described again and may be similar to the solvent described above, e.g., with respect toFIG.1.

In other embodiments the first mixture may include a third liquid comprising essentially the first homopolymer from a third supply tank 3 and a fourth liquid comprising essentially the second homopolymer from a fourth supply tank 4 in addition to the first liquid and the second liquid.

As mentioned above, the first mixture is blended in order to form device features of a semiconductor device using a directed self-assembly (DSA) process.

Although not explicitly described, this embodiment may also include an electronic control system that is coupled to various sensors and data sources to continuously monitor and control the blending process as described with respect toFIG.1above and using the flow chart ofFIG.5below.

FIGS.3A-3Eillustrates cross-sectional views of a semiconductor device during various stages of fabrication in accordance with an embodiment of the present application, whereFIG.3Aillustrates the device after forming a patterned photoresist layer,FIG.3Billustrates the device after coating a mixture comprising a blended block copolymer,FIG.3Cillustrates the device after annealing,FIG.3Dillustrates the device after selectively removing a plurality of regions, andFIG.3Eillustrates the device after forming a first pattern of device elements.

Referring toFIG.3A, a first patterned photoresist layer308is formed over the semiconductor substrate120. This stage of processing may be performed at any stage of the device fabrication such as fin formation, gate formation, metal lines, contact plugs, vias, and so on.

The semiconductor substrate120includes a semiconductor body320supporting a first layer to be patterned306on which the first patterned photoresist layer308is formed. The semiconductor body320may be bulk substrate such as a bulk silicon substrate, a silicon-on-insulator substrate, a silicon carbide substrate, a gallium arsenide substrate, or hybrid substrates such as gallium nitride on silicon and other heteroepitaxial substrates, or any other configuration and material known by one with ordinary skill in the art.

The first layer to be patterned306may be the layer that forms the device feature or it may be an intervening layer that is used to subsequently form the device feature. An example of such an intervening layer may be a hard mask layer that is used to subsequently pattern a feature in an underlying layer. In various embodiments, the first layer to be patterned306may be an insulating layer, a conductive layer, a semiconductor layer depending on the feature being fabricated at this stage of fabrication.

As known to a person having ordinary skill in the art, embodiments of the present invention contemplate the presence of other intervening layers. For example, an antireflective coating layer307may be formed before forming the first patterned photoresist layer308. The antireflection coating (ARC) film may comprise a silicon antireflection coating in one embodiment. In certain embodiments, the antireflective coating layer307may comprise an organic ARC layer, a metal ARC layer, a metal oxide ARC layer, or a titanium nitride ARC layer. The antireflective coating layer307has to also avoid interaction between material of the directed self-assembly being formed (i.e., the first or second homopolymer chains present in the first mixture being deposited as will be described below) and the underlying first layer to be patterned306.

In various embodiments, the first patterned photoresist layer308serves as a first DSA template in that the underlying features are aligned to the first patterned photoresist layer308. The first patterned photoresist layer308may comprise a positive, a negative, or a hybrid photoresist. In one embodiment, the first patterned photoresist layer308is formed by spin coating a resist material over the first layer to be patterned306, baking the resist material to form a photoresist, exposing the photoresist using lithography, and developing the exposed photoresist.

The first patterned photoresist layer308has an opening thus formed with a specific width302and critical dimension304defined during the lithographic process. Advantageously, the dimensions of the specific width302and critical dimension304are much larger than the feature being formed, and therefore a lower resolution (therefore lower cost) lithography process can be used to form these features.

Referring toFIG.3B, the first mixture310, blended in the mixer114within the same fabrication facility, is coated within the first patterned photoresist layer308via the first mixer apparatus100or the second mixer apparatus200as discussed in more detail above with respect toFIG.1andFIG.2. For sake of clarity, the filling of the adjacent openings of the first patterned photoresist layer308is not shown inFIGS.3B-3E. The first mixture310is coated over the first patterned photoresist layer308and fills the openings between the patterns of the first patterned photoresist layer308.

In one embodiment, the first mixture310has a first ratio of the first liquid comprising a first block copolymer liquid to the second liquid comprising a second block copolymer liquid. In another embodiment, the first mixture310is a mixture of a first block copolymer liquid blended with a solvent as described inFIG.1or2. In yet another embodiment, the first mixture310is a mixture of a first block copolymer liquid blended with a homopolymer as described inFIG.1or2. Accordingly, in various embodiments, the first mixture310has first block copolymer liquid blended with one or more of a second block copolymer liquid, a solvent, or a homopolymer as described inFIG.1or2.

Referring toFIG.3C, the semiconductor substrate120is annealed which causes the first homopolymer and the second homopolymer, present in the first mixture310, to separate and form a first plurality of regions312and a second plurality of regions314that alternate between each homopolymer and are aligned with the first patterned photoresist layer308. The first plurality of regions312correspond to the first homopolymer and the second plurality of regions314correspond to the second homopolymer. In various embodiments, the pitch between neighboring first plurality of regions312or between neighboring second plurality of regions314may vary between 10 nm to 100 nm, thus enabling forming structures that are lower than the resolution limit of the lithography process used to pattern the first patterned photoresist layer308.

Annealing may include furnace annealing, lamp based annealing, rapid thermal annealing, or any other annealing method known by one with ordinary skill in the art. In various embodiments, the annealing may be performed between 100° C. to 700° C., and in one embodiment between 200° C. and 400° C.

As is known to a person having ordinary skill in the art, the chemical composition of the block copolymer may be tailored by varying the composition and mole fraction of the homopolymers to control the type of phase separation after annealing. During annealing, the homopolymers undergo microphase separation forming repeating patterns or periodic structures. The type of pattern may be spheres of the first homopolymer embedded in a matrix of the second homopolymer (or vice versa), hexagonal close packed cylinders of the first homopolymer embedded in a matrix of the second homopolymer (or vice versa), gyroid, or lamellae of alternating first homopolymer and second homopolymer. Of these possible structures, from a lithography perspective, lines can be formed from alternating lamellae while the hexagonal closed packed cylinders can be used for forming an array of contact holes. In the illustration described herein, the first plurality of regions312and the second plurality of regions314are selected to form in a lamellar shape. However, in other embodiments, the first plurality of regions312and the second plurality of regions314may be selected to form cylinders of the first plurality of regions312in the second plurality of regions314(or vice versa).

Further, one of the homopolymers has more affinity towards the first patterned photoresist layer308and is formed contacting the sidewalls of the first patterned photoresist layer308. In this example illustration, the first plurality of regions312preferentially forms on the sidewalls of the first patterned photoresist layer308.

Referring toFIG.3D, one of either the first plurality of regions312or the second plurality of regions314is selectively removed forming a first etch mask in the first patterned photoresist layer308. In various embodiments, the first plurality of regions312corresponding to the first homopolymer are removed and the second plurality of regions314corresponding to the second homopolymer form a first etch mask in the first patterned photoresist layer308. In alternative embodiments, the second plurality of regions314corresponding to the second homopolymer may be selectively removed and the first plurality of regions312corresponding to the first homopolymer may form the first etch mask.

The removal of the first plurality of regions312or the second plurality of regions314may be performed using either wet or dry chemistry. For example, a dry oxygen plasma may be used to remove a poly methyl-methacrylate. If the selectivity of this etch process is poor, some of the second plurality of regions314will be removed while removing the first plurality of regions312. In some embodiments, this may be used to advantageously reduce the critical dimension of the remaining second plurality of regions314. However, lateral etching of the second plurality of regions314may not be preferred in certain embodiments, as it may be difficult to control the vertical nature of the sidewall profile needed for patterning the layer to be patterned306in the next step.

Referring toFIG.3E, using the first etch mask, the first pattern of device elements316with a first critical dimension318and a first pitch321are formed in the layer to be patterned306. In this case, the first patterned photoresist layer308is removed prior to the etching. Of course if a plurality of trenches is being formed in the layer to be patterned306, the first patterned photoresist layer308may be removed after the patterning of the layer to be patterned306. As known to a person having ordinary skill in the art, an anisotropic reactive ion etching process may be used to pattern the layer to be patterned306. Any remaining second plurality of regions314is removed as well after patterning the layer to be patterned306.

As previously described, the first critical dimension318and the first pitch321formed are based on the first ratio of the liquids being blended in the first mixture, e.g., ratio of first block copolymer and second block copolymer or ratio of first block copolymer and a homopolymer. The first patterned photoresist layer308and the etch mask formed by the second plurality of elements are removed.

FIG.4is a flow chart of a first directed self-assembly method to form a first pattern of device elements in accordance with an embodiment of the present disclosure.

In block402, a first patterned photoresist layer308is formed over a first layer to be patterned306that is formed over a semiconductor substrate120. This first patterned photoresist layer308may be formed as described and illustrated usingFIG.3A.

As next illustrated in block404and described with respect toFIG.3B, the first patterned photoresist layer308is coated with the first mixture310. The forming of the first mixture310is described with respect toFIGS.1and2. In various embodiments, as discussed above, the first mixture310is a combination of two or more of a first block copolymer, a second block copolymer, a solvent, and a homopolymer that are blended using the first mixer apparatus100or the second mixer apparatus200. Advantageously, the blending of the first mixture310and the coating of the first mixture310over the semiconductor substrate120happens in the same fabrication facility. Further, this blending may happen closely spaced in time with the coating process to avoid chemical deterioration due to extended storage.

Referring next to block406and described with respect toFIG.3C, the substrate is annealed to form a first plurality of regions312and a second plurality of regions314.

As next illustrated in block408and described with respect toFIG.3D, the first plurality of regions312is selectively removed to form a first etch mask.

As next illustrated in block410and described with respect toFIG.3E, after removing any remaining first patterned photoresist layer, a first pattern of device elements316is formed using the first etch mask.

As mentioned above, an advantage of blending block copolymers within a fabrication facility is that if a metric of the first formed pattern does not meet a target metric, the blended block copolymer mixture can be tuned within the fabrication facility in lieu of ordering a new mixture from a vendor.

FIG.5a flow chart of a method for tuning a first block copolymer mixture within a fabrication facility in order to meet a target metric.

As illustrated in block502, a block copolymer (BCP) mixture such as the first mixture310is blended within the fabrication facility using the first mixer apparatus100or the second mixer apparatus200, as described above usingFIG.1andFIG.2, respectively. In various embodiments, as discussed above, the first mixture310is a combination of two or more of a first block copolymer, a second block copolymer, a solvent, and a homopolymer that are blended using the first mixer apparatus100or the second mixer apparatus200.

It is conceivable that during production or during process development, the features of the pattern or the blended mixture may not be within a desired target window. This may eventually cause a loss in product yield and therefore embodiments of the present disclosure envision a process control in which the metrics measured at blocks503and506are actively or periodically monitored and provided to an electronic flow control system115such as described inFIG.1.

As next illustrated in block503, the blended block copolymer mixture, the first liquid, or the second liquid may be analyzed with various metrology tools including sensors such as sensors103described with respect toFIG.1. Alternatively, or in addition, to the above metrology of block503, as next illustrated in block504, a semiconductor substrate120is coated with the first mixture310and a pattern of device elements316is formed on the semiconductor substrate120as described usingFIGS.3A-3E,4above. In this case, a metric of the pattern of device elements316is measured. In further embodiments, a pattern of the second plurality of regions314is measured prior to forming the device elements316. Accordingly, in various embodiments, the measured metric may be the critical dimension of the device elements316/second plurality of regions314, the width (dimension orthogonal to the critical dimension) of the device elements316/second plurality of regions314, the height or the depth of the device elements316/second plurality of regions314, the distance between neighboring elements, i.e., the pitch of the device elements316/second plurality of regions314, the surface roughness of the device elements316/second plurality of regions314, the local critical dimension uniformity of the device elements316/second plurality of regions314, the line width variation of the device elements316/second plurality of regions314, the sidewall angle of the device elements316/second plurality of regions314, the microphase structure, or any other metric. These metrology measurements may be made using inline tools such as optical metrology tools such as scatterometry that use non-destructive testing or other metrology tools that may use destructive testing such as using optical or electron microscopy.

The measured metric is compared to a target metric or target process window, for example, obtained from process recipe/metrics105described inFIG.5. This may be done in the electronic control system described inFIG.1, for example. If the measured metric is the same as the target metric or within the process window, no change to the blended liquid or to the process is made at this time. If the measured metric is different than the target metric or outside the process window, the process continues to step510and a new or modified recipe for the block copolymer mixture is generated in accordance withFIG.1orFIG.2. The new mixture may change any of the process parameters such as flow rate and/or pressure of the first liquid or the second liquid, temperature as well as other parameters.

In various embodiments, if the target metric is the critical dimension or pitch, and the measured critical dimension or pitch does not meet the target metric, the first mixture can be further blended with a third liquid comprising essentially of the first homopolymer or essentially the second homopolymer to form a tuned second mixture with a new critical dimension or pitch.

In alternative embodiments, if the target metric is the critical dimension or pitch, and the measured critical dimension or pitch does not meet the target metric, the first mixture can be further blended with a third liquid comprising essentially of the first homopolymer and a fourth liquid comprising essentially of the second homopolymer to form a tuned second mixture with a new critical dimension or pitch.

In alternative embodiments, if the target metric is the surface roughness and the measured surface roughness does not meet the target surface roughness, the first mixture can be further blended with a third liquid comprising a solvent to form a new mixture with an improved film thickness. For example, the solvent may comprise of propylene glycol monomethyl ether acetate, toluene, or any other solvent known to change the film thickness of block copolymers known in the art.

In alternative embodiments, the microphase of the first mixture may be improper. For example, the microphase may be hexagonal instead of lamellar. In such cases, the first mixture may be further blended with a third liquid comprising essentially of the first homopolymer or essentially of the second homopolymer in order to change the phase of the blended mixture from hexagonal to lamellae and vice-versa. In various embodiments, as previously described, the phase may be changed between close-packed cylinders, hexagonal, and lamellae by changing the composition of the homopolymers in the block copolymers.

The process of blocks502through508are repeated with the new mixture blended or modified with the new process recipe.

As mentioned above, another advantage of the disclosed invention is that it allows for multiple layers of IC device elements with different critical dimensions, pitches, and/or shapes to be fabricated on the same semiconductor substrate by blending multiple block copolymer mixtures corresponding to each successive layer of device elements within the fabrication facility.

FIGS.6A-6Billustrate cross-sectional views of a semiconductor device during various stages of fabrication in accordance with an embodiment of the present application, whereinFIG.6Aillustrates the device after coating a second patterned photoresist layer with a second block copolymer mixture, andFIG.6Billustrates the device after forming a second patterned layer of device elements.FIG.7is a flow chart of a second DSA method used to form a second layer of device elements for the fabrication process illustrated inFIGS.6A-6B.

In this embodiment, a blended mixture with a different composition is formed using the same supply tanks that were previously used to pattern device elements for a different process step. Advantageously, different critical dimensions can be achieved with the same mixing apparatus without having to change supply bottles.

Accordingly, this embodiment continues fromFIG.3E. Referring now toFIG.6Aand block702, an interlayer dielectric layer606is formed over device elements316formed inFIG.3E, for example. The interlayer dielectric layer606may comprise a plurality of layer and may comprise SiO2, SION, Si3N4, glasses such as borosilicate glass, organo silicate glass, low-k dielectric materials, or any other interlayer dielectric known by one with ordinary skill in the art.

Next, a second layer to be patterned608is formed over the interlayer dielectric layer606(block704) and may also comprise a dielectric layer, a conductive layer, or semiconductor layer depending on the feature being formed.

Next, a second patterned photoresist layer is formed over the second layer to be patterned608(block706). As illustrated inFIG.6A, a second patterned photoresist layer610is formed over the second layer to be patterned608. The second patterned photoresist layer610may comprise the same material and may be formed in the same manner as the first patterned photoresist layer308, as illustrated inFIG.3A. The second patterned photoresist layer610is patterned with a second specific pitch602and a second specific critical dimension604. The second patterned photoresist layer610serves as a second DSA template.

The second patterned photoresist layer610is coated with the second mixture (block708). The second mixture has a composition that is different from the first mixture used inFIG.3B. In one embodiment, the second mixture has a second ratio of the first liquid comprising a first block copolymer liquid to the second liquid comprising a second block copolymer liquid. The second ratio is selected to achieve a target second critical dimension for the features being patterned while the first ratio was selected to achieve a different target first critical dimension for the features being patterned. Similar to the first mixture, in various embodiments, the second mixture has first block copolymer liquid blended with one or more of a second block copolymer liquid, a solvent, or a homopolymer as described inFIG.1or2. Similar to the first mixture, the second mixture is then coated onto the second patterned photoresist layer610via the first mixer apparatus100or the second mixer apparatus.

Referring to block710, a second etch mask612is formed by annealing the substrate to cause microphase separation (e.g., similar toFIG.3D) and then removing one of the phase regions.

Referring toFIG.6B, using the second etch mask612, a second pattern of device elements616with a second critical dimension618and a second pitch620are formed (block712). The second critical dimension618and the second pitch620formed are based on the second ratio of the first liquid to the second liquid in the second mixture. The second patterned photoresist layer610and the second etch mask612are removed (block714).

In various embodiments, the first DSA process is used to form a first pattern of gate lines and the second DSA process is used to form a second pattern of metal lines over the gate lines. In alternative embodiments the first DSA process is used to form a first pattern of gate lines and the second DSA process is used to form a second pattern of contact holes within the gate lines.

Advantageously, as discussed in the embodiments described usingFIGS.3A-3Eand thenFIGS.6A-6B, two different patterns with different critical dimensions and pitch may be formed using a common source of supply tanks. This advantage scales quickly if more levels use a directed self-assembly process as additional patterns at other critical dimensions may be fabricated with the same number of supply tanks/liquids.

Examples of embodiments are described below.

Example 1. A method for forming a device includes blending, in a mixer within a fabrication facility, a first liquid including a first block copolymer with a second liquid including a second block copolymer to form a first mixture, the first block copolymer including a first homopolymer and a second homopolymer, the first homopolymer having a first mole fraction in the first liquid, the second block copolymer including the first homopolymer and the second homopolymer, the first homopolymer having a second mole fraction in the second liquid, the first mole fraction being different from the second mole fraction; placing a substrate over a substrate holder of a processing chamber within the fabrication facility; and coating the substrate with the first mixture within the processing chamber.

Example 2. The method of example 1, further including: forming a patterned photoresist layer over a layer to be patterned that is disposed over the substrate, where coating the substrate with the first mixture includes coating the patterned photoresist layer with the first mixture; annealing to form a first plurality of regions including the first homopolymer and a second plurality of regions including the including the second homopolymer; selectively removing the first plurality of regions to form an etch mask aligned with the patterned photoresist layer, the etch mask including the second plurality of regions; and forming a pattern in the layer to be patterned using the etch mask.

Example 3. The method of one of examples 1 or 2, further including removing the patterned photoresist layer, and removing the second plurality of regions after forming the pattern.

Example 4. The method of one of examples 1 to 3, further including: forming a first pattern from the coating of the first mixture; measuring a first critical dimension of a feature of the first pattern; in response to determining that the first critical dimension is different from a target critical dimension, blending, at the mixer, the first liquid with the second liquid to form a second mixture, the first mixture including a first ratio of the first block copolymer with the second block copolymer, the second mixture including a second ratio of the first block copolymer with the second block copolymer, the second ratio being different than the first ratio; and coating a further substrate with the second mixture; and forming a second pattern from the coating of the second mixture, where a second critical dimension of a feature of the second pattern meets a target critical dimension.

Example 5. The method of one of examples 1 to 4, further including: blending, at the mixer, the first liquid with the second liquid to form a second mixture, the first mixture including a first ratio of the first block copolymer with the second block copolymer, the second mixture including a second ratio of the first block copolymer with the second block copolymer, the second ratio being different than the first ratio; and coating the substrate with the second mixture.

Example 6. The method of one of examples 1 to 5, further including: forming a first pattern by using a first directed self-assembly process based on the first mixture; and forming a second pattern by using a second directed self-assembly process based on the second mixture, where a first critical dimension of a feature of the first pattern is different from a second critical dimension of a feature of the second pattern.

Example 7. The method of one of examples 1 to 6, where the first directed self-assembly process includes: forming a first patterned photoresist layer over a first layer to be patterned disposed over the substrate, where coating the substrate with the first mixture includes coating the first patterned photoresist layer with the first mixture, annealing to form a first plurality of regions including the first homopolymer and a second plurality of regions including the second homopolymer, selectively removing the first plurality of regions to form a first etch mask aligned with the first patterned photoresist layer, the first etch mask including the second plurality of regions, and forming the first pattern in the first layer to be patterned using the first etch mask; and where the second directed self-assembly process includes forming, a second patterned photoresist layer over a second layer to be patterned disposed over the substrate, where coating the substrate with the second mixture includes coating the second patterned photoresist layer with the second mixture, annealing to form a third plurality of regions including the first homopolymer and a fourth plurality of regions including the second homopolymer, selectively removing the third plurality of regions to form a second etch mask aligned with the second patterned photoresist layer, the second etch mask including the fourth plurality of regions, and forming a second pattern in the second layer to be patterned using the second etch mask.

Example 8. The method of one of examples 1 to 7, where the first pattern is a pattern for gate lines, and where the second pattern is a pattern for metal lines over the gate lines.

Example 9. The method of one of examples 1 to 8, where the first pattern is a pattern for gate lines, and where the second pattern is a pattern to form contact holes in the gate lines.

Example 10. The method of one of examples 1 to 9, where coating the substrate includes: spinning the substrate holder with the substrate; and injecting the first mixture through a nozzle connected to the mixer, the nozzle being directed towards the substrate in order to coat the substrate with the first mixture.

Example 11. The method of one of examples 1 to 10, where, during the blending, the method further includes adding a third liquid including essentially the first homopolymer to form the first mixture.

Example 12. The method of one of examples 1 to 11, where, during the blending, the method further includes adding a fourth liquid including essentially the second homopolymer to form the first mixture.

Example 13. A method for forming a device includes blending, in a mixer within a fabrication facility, a first block copolymer and a solvent to form a first mixture, the first block copolymer including a first homopolymer and a second homopolymer; placing a substrate over a substrate holder of a processing chamber within the fabrication facility; and coating the substrate with the first mixture within the processing chamber.

Example 14. The method of example 13, further including: forming a first pattern from the coating of the first mixture; measuring a first metric of a feature of the first pattern; in response to determining that the first metric is different from a target metric, blending, at the mixer, the first block copolymer with the solvent to form a second mixture, the first mixture including a first ratio of the first block copolymer with the solvent, the second mixture including a second ratio of the first block copolymer with the solvent, the second ratio being different than the first ratio; and coating a further substrate with the second mixture; and forming a second pattern from the coating of the second mixture, where a second metric of a feature of the second pattern meets a target metric.

Example 15. The method of one of examples 13 or 14, where the first metric, second metric, and the target metric are measures of a surface roughness.

Example 16. The method of one of examples 13 to 15, further including: forming a patterned photoresist layer over a layer to be patterned that is disposed over the substrate, where coating the substrate with the first mixture includes coating the patterned photoresist layer with the first mixture while delivering a solvent to the first mixture; annealing to form a first plurality of regions including the first homopolymer and a second plurality of regions including the including the second homopolymer; selectively removing the first plurality of regions to form an etch mask aligned with the patterned photoresist layer, the etch mask including the second plurality of regions; and forming a pattern in the layer to be patterned using the etch mask.

Example 17. A method for forming a device includes blending, in a mixer within a fabrication facility, a first liquid including a first block copolymer and a second liquid including essentially a first homopolymer to form a first mixture, the first block copolymer including the first homopolymer and a second homopolymer; placing a substrate over a substrate holder of a processing chamber within the fabrication facility; and coating the substrate with the first mixture within the processing chamber.

Example 18. The method of example 17, where, during the blending, the method further includes adding a third liquid including essentially the first homopolymer to form the first mixture.

Example 19. The method of one of examples 17 or 18, where, during the blending, the method further includes adding a third liquid including essentially a solvent to form the first mixture.

Example 20. The method of one of examples 17 to 19, further including: forming a first pattern from the coating of the first mixture; measuring a first critical dimension of a feature of the first pattern; in response to determining that the first critical dimension is different from a target critical dimension, blending, at the mixer, the first liquid with the second liquid to form a second mixture, the first mixture including a first ratio of the first liquid with the second liquid, the second mixture including a second ratio of the first liquid with the second liquid, the second ratio being different than the first ratio; and coating a further substrate with the second mixture; and forming a second pattern from the coating of the second mixture, where a second critical dimension of a feature of the second pattern meets a target critical dimension.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.