Patent ID: 12237213

DETAILED DESCRIPTION OF EMBODIMENTS

In order to make the above objectives, features and advantages of the present disclosure obvious and understandable, hereinafter embodiments of the present disclosure are described in detail in combination with the drawings.

Many details are set forth in following description to facilitate a full understanding of the present disclosure. The present disclosure may further be implemented in other ways different from those described herein. Those skilled in the art may deduct by analogy without violating a core concept of the present disclosure. Therefore, the present disclosure is not limited to embodiments disclosed below.

The present disclosure is described in detail in conjunction with the schematic diagrams. When embodiments of the present disclosure are described in detail, a part of a device may not be enlarged according to a general scale in a sectional view showing a structure of the device, in order to facilitate illustration. The schematic diagrams are only exemplary, which should not be construed as limitation on the protection scope of the present disclosure. In addition, dimensions in a three-dimensional space, for example, including a length, a width, and a depth should be set in actual manufacture.

At present, self-alignment techniques are important means to implement alignment between different layers. The self-alignment is commonly utilized to implement alignment between a metal layer and an interconnection layer.

After a source, a drain, or a gate of a semiconductor device is formed, there is no effective self-alignment technique capable to align a contact hole, which is configured to connect the source, the drain, or the gate with outside (lead the source, the drain, or the gate out), accurately with the source, the drain, or the gate when forming the contact hole.

In order to address the above issue, a method for manufacturing a semiconductor device is provided according to an embodiment of the present disclosure. The semiconductor device includes a substrate and a to-be-connected structure disposed on a side of the substrate. A photolithographic coating is formed on the to-be-connected structure. The photolithographic coating includes a first film, a photolithographic film, and a second film, which are stacked in the above-listed sequence. Refractive indexes of the first film and the second film are smaller than 1, so that the photolithographic coating forms an optical structure with a high reflection coefficient. Then, the photolithographic coating is exposed to a light having a first wavelength. The to-be-connected structure is reflected in the photolithographic coating, and hence serves as a mask and is imaged to a first region of the photolithographic film. Afterwards, the photolithographic coating is exposed to a light having a second wavelength through a mask. The mask is imaged to a second region of the photolithographic film. A region in which the first region and the second region overlap serves as a connection region corresponding to the to-be-connected structure. That is, positions at the to-be-connected structure are imaged into the first region of the photolithographic film after the exposure with the light having the first wavelength, and the pattern of the mask is imaged to the second region of the photolithographic film after the exposure with the light having the second wavelength. The region in which the first region overlaps the second region corresponds to the to-be-connected structure, and thereby self-alignment between a layer of the to-be-connected structure and a layer where the contact hole is arranged is implemented. Only the region in which the imaging regions of the two exposures overlap corresponds to the to-be-connected structure, which improves accuracy of the alignment between different layers and reduces the error of the alignment.

In order to facilitate understanding technical solutions and technical effects of the present disclosure, hereinafter embodiments are described in detail in conjunction with the drawings.

Reference is made toFIG.1, which is a flowchart of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure. In this embodiment, a semiconductor device100includes a substrate110and a to-be-connected structure120disposed on a side of the substrate110. Reference is made toFIG.2andFIG.3.FIG.2is atop view of a structure of a semiconductor device100according to an embodiment of the present disclosure, andFIG.3is a cross-sectional view along a direction indicated by AA, of the semiconductor device as shown inFIG.2. In this embodiment, the to-be-connected structure120may be at least one of a gate structure, a source structure, or a drain structure. The to-be-connected structure120may be made of a metal material having good conductivity. In another embodiment, the to-be-connected structure may be a structure in a layer serving as a target of alignment.

In one embodiment, the substrate110is a semiconductor substrate, such as a Si substrate, a Ge substrate, a SiGe substrate, an SOI (silicon on insulator) substrate, or a GOI (germanium on insulator) substrate. In another embodiment, the semiconductor substrate may be a substrate including another elementary semiconductor or another compound semiconductor, such as quartz, GaAs, InP, or SiC. The semiconductor substrate may alternatively be a stacked structure such as Si/SiGe, or another epitaxial structure such as SGOI (silicon-germanium on insulator). In this embodiment, the substrate110is a silicon substrate.

In practical applications, another film may be formed between the substrate110and the to-be-connected structure120, so as to form various semiconductor devices.

As an example, stacked layers and a channel structure running through the stacked layers are formed between the substrate110and the to-be-connected structure120. In such case, the semiconductor device may be a three-dimensional memory device.

As another example, a doped layer or another dielectric film is formed between the substrate110and the to-be-connected structure120. In such case, the semiconductor device may be a logic device, such as a transistor.

The method includes the following steps S101to S103.

In step S101, a photolithographic coating130is formed on the to-be-connected structure120. Reference is made toFIG.4.

In embodiments of the present disclosure, the photolithographic coating130is formed on the to-be-connected structure120. The photolithographic coating130is patterned, such that a metal contact is formed through the patterned photolithographic coating130, and the to-be-connected structure130is electrically connected to outside (led out) via the metal contact.

In practical applications, before the photolithographic coating130is formed on the to-be-connected structure120, a dielectric layer140is first formed on the to-be-connected structure120. That is, the dielectric layer140is disposed between the to-be-connected structure120and the photolithographic coating130, as shown inFIG.4. The dielectric layer140may be made of a material with good insulation, such as silicon oxide. The dielectric layer140may be formed by depositing a dielectric material through deposition techniques. When the dielectric material is deposited on the to-be-connected structure120, the formed dielectric layer140is conformal with the to-be-connected structure120, so that morphology of the dielectric layer140is similar to that of the to-be-connected structure120. In such case, the dielectric layer140may be ground by a device for chemical mechanical grinding. Hence, the obtained dielectric layer140has high flatness, and the photolithographic coating130can be formed on the flat dielectric layer140in a subsequent step.

In embodiments of the present disclosure, the photolithographic coating130includes a first film131, a photolithographic film132, and a second film133that are stacked in the above-listed sequence. Refractive indexes of the first film131and the second film132are smaller than 1. An optical structure of the photolithographic coating130including the first film131, the photolithographic film132, and the second film133is similar to a sandwich. Two outer layers of the photolithographic coating are films each having a refractive index smaller than 1. An incident light is reflected and oscillates in the photolithographic coating130, and hence intensity of the incident light is enhanced by the reflection and the oscillation.

The photolithographic film132is made of a photoresist. Each of the first film131and the second film133may be made of a metal material or a metamaterial. The metal material may be, for example, gold, silver, or copper, which has a refractive index smaller than 1 for a deep-ultraviolet, visible, or infrared light. The metamaterial may be a combination of some compound materials and certain materials. The metamaterial may be synthetic to achieve the refractive index smaller than 1 for light having a certain wavelength.

In practical application, the first film131, the photolithographic film132, and the second film133, which are sequentially stacked, may be formed through spin coating techniques, deposition techniques, or ion sputtering techniques. The first film131, the photolithographic film132, and the second film133may be ground by a device for chemical mechanical grinding, to control flatness and thicknesses of the first film131, the photolithographic film132, and the second film133, respectively.

In step S102, the photolithographic coating130is exposed to a light having a first wavelength. Reference is made toFIG.5.

In embodiments of the present disclosure, the photolithographic coating130may be exposed through photolithography techniques, after the photolithographic coating130is formed on the to-be-connected structure120.

The photolithographic coating130is first exposed to the light having the first wavelength. In the exposure, the photolithographic coating130is directly irradiated by a collimated light, and there is no mask. The photolithographic coating130provides high reflectivity for the light having the first wavelength, and the to-be-connected structure120under the photolithographic coating130can be imaged to a first region132-1of the photolithographic film132, as shown inFIG.5. That is, when the photolithographic coating130is exposed to the light having the first wavelength, the to-be-connected structure120is equivalent to a mask, and the light having the first wavelength induces a photo-chemical reaction in the first region132-1to image the to-be-connected structure120to the photolithographic film132.

In embodiments of the present disclosure, thicknesses of the first film131, the photolithographic film132, and the second film133in the photolithographic coating130may be obtained through simulation in software. Generally, a thickness of the photolithographic film132is greater than thicknesses of the first film131and the second film133. The thickness of the photolithographic film132affects an intensity of the light in the photolithographic film132, during the exposure with the light having the first wavelength.

Reference is made toFIG.6, which is a schematic diagram showing correspondence between the thickness of the photolithographic film and the intensity of the light according to an embodiment of the present disclosure. As can be seen fromFIG.6, the intensity of the light having the first wavelength changes in the photolithographic film132along with the thickness of the photolithographic film132. In this embodiment, a thickness of the photolithographic film132may be selected in correspondence to a case in which the light having the first wavelength in the photolithographic film132has maximum intensity, so that the to-be-connected structure120is imaged to the photolithographic film132with maximum efficiency.

In step S103, the photolithographic coating130is exposed to a light having a second wavelength through a mask150. Reference is made toFIG.7.

In embodiments of the present disclosure, the photolithographic coating130may be further exposed to the light having the second wavelength through the mask150, after being subject to the exposure with the light having the first wavelength. The to-be-connected structure120would not be reflected in the photolithographic film132, after the light having the second wavelength strikes on the photolithographic coating130. That is, the light having the second wavelength does not image the to-be-connected structure120to the photolithographic film132.

In other words, the light having the second wavelength images only a pattern of the mask150to the second region132-2of the photolithographic film132, and does not image the to-be-connected structure120to the photolithographic film132. The light having the second wavelength induces a photo-chemical reaction in the second region132-2, and thereby images the pattern of the mask150to the photolithographic film132.

In embodiments of the present disclosure, the photolithographic film132has an optical response to both the light having the first wavelength and the light having the second wavelength. When the photolithographic film is first exposed to the light having the first wavelength, a photochemical reaction occurs in the first region132-1of the photolithographic film132, and hence a position of the to-be-connected structure120is determined. When the photolithographic film is then exposed to the light having the second wavelength, a photochemical reaction occurs in the second region132-2of the photolithographic film132, and hence a position of a contact hole is determined. Photochemical reactions occur in both exposures in a region in which the first region132-1and the second region132-2overlap, and such region serves as a connection region corresponding to the to-be-connected structure120.

In other words, only the region in which imaging regions of the two exposures overlap in the photolithographic film is considered to correspond to the to-be-connected structure. Only the photolithographic film in the connection region would be developed through development techniques in a subsequent step. The other part of photolithographic film, in which only one photochemical reaction occurs or no photochemical reaction occurs, would not be developed. Thereby, achieved is self-alignment between a layer of the to-be-connected structure and a layer in which the contact hole is located, improving accuracy of alignment between different layers and reducing an error of the alignment.

In embodiments of the present disclosure, the light having the first wavelength is capable to image the to-be-connected structure120to the photolithographic film132, and the light having the second wavelength is capable to image the pattern of the mask150to the photolithographic film132. For example, the light having the first wavelength may be a visible light or an ultraviolet light, and the light having the second wavelength may be an ultraviolet light or a visible light. In a case that the second wavelength is smaller than the first wavelength, the pattern of the mask is imaged with higher resolution, and the position of the contact hole is determined more accurately, which facilitates the self-alignment between the layer of the to-be-connected structure and the layer in which the contact hole is arranged. In a case that the first wavelength is smaller than the second wavelength, a fine structure of the to-be-connected structure is reflected in the photolithographic film with high precision, which facilitates increasing a margin for alignment and overlay of the mask and reducing a mask error factor.

As an example, the first wavelength is 633 nm or 532 nm, and the second wavelength is 365 nm, 248 nm, or 193 nm.

As another example, the first wavelength is 365 nm, 248 nm, or 193 nm, and the second wavelength is 532 nm or 633 nm.

In an embodiment, reference is made toFIG.8, which is a schematic top view of a semiconductor device and a mask according to an embodiment of the present disclosure.FIG.7is a cross-sectional view of the semiconductor device and the mask as shown inFIG.8along a direction indicated by BB. A position at which the pattern of the mask150is exposed is located in the first region132-1of the photolithographic film132, and a feature size of the pattern of the mask150is larger than that of the to-be-connected structure120, as shown inFIG.8. An exposure size of the pattern of the mask150is S, a feature size of the to-be-connected structure120is M. and S is greater than M. Even if a center of the pattern of the mask150deviates from a center of the to-be-connected structure120, an overlapping region between the pattern of the mask150and the to-be-connected structure120can still be ensured to have a maximum area, hence achieving self-alignment.

As shown inFIG.8, the pattern of the mask may be consistent with a shape of a hole, so as to form a contact hole in a subsequent step. The mask may be a binary mask or an attenuated phase shift mask. A substrate of the mask may be made of quartz or other non-opaque material. An opaque part of the mask may be formed by a metal material such as chromium.

In embodiments of the present disclosure, when the mask150is imaged by the light having the second wavelength in the photolithographic film130, the photochemical reactions or the developing techniques are controlled, such that only a region irradiated by both the light having the second wavelength and the light having the first wavelength is subject to a secondary photo-chemical reaction and then developed in a subsequent step. The region irradiated by both the light having the second wavelength and the light having the first wavelength serves as the connection region1001.

In embodiments of the present disclosure, the photolithographic film132in a certain region may be modified through laser heating and laser curing, such that the certain region is hard to form an image with the light having the second wavelength. The certain region may be a region other than the first region132-1.

In embodiments of the present disclosure, the second film133may be removed after the second exposure of the photolithographic coating130, to facilitate developing the photolithographic film132to form a patterned photolithographic film160. Reference is made toFIG.9. After the development, the photolithographic film132corresponding to the connection region1001is removed.

Afterwards, the dielectric layer140corresponding to the connection region1001is etched through the patterned photolithographic film160, to obtain a contact hole170running through the dielectric layer140. Thereby, the to-be-connected structure120is exposed by the contact hole170, as shown inFIG.10. The first film131is also etched when the dielectric layer is etched through the patterned photolithographic film160. After the contact hole170running through the dielectric layer140is obtained, the remaining photolithographic film160and the remaining first film131are removed, and only the dielectric layer140having the contact hole170is retained.

After the contact hole170is formed at a position corresponding to the to-be-connected structure120, a metal material is filled in the contact hole170to form a metal contact180. The metal contact180is connected with the to-be-connected structure120, that is, the to-be-connected structure120is electrically connected to outside, as shown inFIG.11.

In embodiments of the present disclosure, the photolithography techniques for forming the metal contact may be extreme ultraviolet photolithography techniques, deep ultraviolet photolithography techniques, nanometer imprinting techniques, super diffraction photolithography techniques, or other techniques utilizing optical imaging.

The method for manufacturing the semiconductor device is provided according to embodiments of the present disclosure. The semiconductor device includes the substrate and the to-be-connected structure disposed on the side of the substrate. The photolithographic coating is formed on the to-be-connected structure. The photolithographic coating includes the first film, the photolithographic film, and the second film, which are stacked in the above-listed sequence. The refractive indexes of the first film and the second film are smaller than 1, so that the photolithographic coating forms an optical structure with a high reflection coefficient. Then, the photolithographic coating is exposed to the light having the first wavelength. The to-be-connected structure is reflected in the photolithographic coating, and hence serves as a mask and is imaged to the first region of the photolithographic film.

Afterwards, the photolithographic coating is exposed to the light having the second wavelength through the mask. The mask is imaged to the second region of the photolithographic film. The region in which the first region and the second region overlap serves as the connection region corresponding to the to-be-connected structure. That is, positions at the to-be-connected structure are imaged into the first region of the photolithographic film after the exposure with the light having the first wavelength, and the pattern of the mask is imaged to the second region of the photolithographic film after the exposure with the light having the second wavelength. The region in which the first region overlaps the second region corresponds to the to-be-connected structure, and thereby self-alignment between a layer of the to-be-connected structure and a layer where the contact hole is arranged is implemented. Only the region in which the imaging regions of the two exposures overlap corresponds to the to-be-connected structure, which improves accuracy of the alignment between different layers and reduces the error of the alignment.

The embodiments of the present disclosure are described in a progressive manner, and each embodiment places emphasis on the difference from other embodiments. Therefore, one embodiment can refer to other embodiments for the same or similar parts. Since apparatuses disclosed in the embodiments correspond to methods disclosed in the embodiments, the description of the apparatuses is simple, and reference may be made to the relevant part of the methods.

The foregoing embodiments are only preferred embodiments of the present disclosure. The preferred embodiments according to the disclosure are disclosed above, and are not intended to limit the present disclosure. With the method and technical content disclosed above, those skilled in the art can make some variations and improvements to the technical solutions of the present disclosure, or make some equivalent variations on the embodiments without departing from the scope of technical solutions of the present disclosure. All simple modifications, equivalent variations and improvements made based on the technical essence of the present disclosure without departing the content of the technical solutions of the present disclosure fall within the protection scope of the technical solutions of the present disclosure.