The present disclosure relates to an integrated biosensor structure and manufacturing method thereof, particularly, the disclosed biosensor structure is an integrated biosensor structure which formed on a complementary metal-oxide-semiconductor (CMOS) chip.
The use of biosensing instruments using disposable sample pieces has been increasing each year, and it is expected to enable simple and quick assay and analysis of a particular component in a biological body fluid such as blood, plasma, urine, saliva, or the whole set of proteins created in a cell at a certain point in time, i.e., a proteome. Moreover, individually tailored medical treatments, in which individuals are treated and administered medicines according to their SNP (acronym for Single Nucleotide Polymorphism) information, are expected to be put into practice in the future by genetic diagnosis using disposable DNA chips.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various structures are not drawn to scale. In fact, the dimensions of the various structures may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper”, “on” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
As used herein, the terms such as “first”, “second” and “third” describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another. The terms such as “first”, “second”, and “third” when used herein do not imply a sequence or order unless clearly indicated by the context.
In some comparative embodiments, biosensors are formed over an ion-sensitive field-effect transistor (ISFET) or formed through SOI technology. As a FET-based biosensor 91 shown in
In the FET-based biosensor 91 shown in
In another comparative embodiment, biosensors can be formed through SOI technology (hereinafter “SOI-based biosensor”). In such embodiments, as an SOI-based biosensor 80 shown in
Therefore, a biosensor having good sensitivity and an acceptable manufacturing cost is provided by some embodiments of the present disclosure. That is, the present disclosure discloses an integrated biosensor structure and that the sensing structure is directly formed on a CMOS structure, which can make the biosensor perform the features of good sensitivity, and the manufacturing cost thereof is acceptable as well.
In some embodiments, the substrate 16 includes different regions configured to perform different functions. As shown in
In some embodiments, the FEOL structure 18 can be formed in/on the substrate 16. In some embodiments, the FEOL structure 18 has a plurality of doped regions at the first surface 16A of the substrate 16. In some embodiments, a portion of the doped regions (e.g., the first doped regions 28) are located within the sensing region 22, while another portion of the doped regions (e.g., the second doped regions 29) are located within the logic region 24. In some embodiments, the doped regions located within the sensing region 22 are configured to perform as terminals in receiving or sensing the change of potential (ΔV) induced by a sensing layer thereon. For example, in the case of the integrated biosensor structure 10 in the present disclosure is used for DNA sequencing, particularly, for non-optical DNA sequencing, a DNA template can be accommodated in the sample-holding structure within the sensing region 22. Then, protons (H+) are released when nucleotides (dNTP) are incorporated into the growing DNA strands, changing the pH of the medium in the sample-holding structure (ΔpH). This progress can induce a change in the surface potential of the sensing layer and a change in the potential (ΔV) of the source terminal in the substrate 16.
Other than the portion of the doped regions located within the sensing region 22, the doped regions within the logic region 24 are configured to perform the functions of the terminals of field-effect transistors (FET), which means these doped regions can be a portion of the transistors within the logic region 24, and generally, these transistors are connected to the BEOL structure 20 thereover. In some embodiments, the signals acquired from the sensing region 22 can be transmitted to other semiconductor devices (e.g., an amplifier circuit) by the structures in the logic region 24.
As shown in
In other embodiments, as shown in
The gate electrode that formed over the gate oxide may be made of polysilicon (POLY) or any other suitable conductive material. The suitable conductive material includes but is not limited to metal (e.g., tantalum, titanium, molybdenum, tungsten, platinum, aluminum, hafnium, ruthenium), metal silicide (e.g., titanium silicide, cobalt silicide, nickel silicide, tantalum silicide), or metal nitride (e.g., titanium nitride, tantalum nitride). In some embodiments, the gate electrode is formed by chemical vapor deposition (CVD), low-pressure chemical vapor deposition, physical vapor deposition (PVD), atomic layer deposition, or spin-on. In some embodiments, the gate structure is formed by forming the gate electrode on the gate oxide, and then patterning the gate electrode by etching to form the gate structure. In some embodiments of the present disclosure, the first gate oxide 30 is thinned down after a removing operation to a polysilicon gate electrode formed thereon, and such thin first gate oxide 30A can be used as an etch stop layer in removing the poly gate electrode to protect the intactness of the doped regions there below within the sensing region 22. In some embodiments, the first gate oxide 30 can be removed in the operation of forming the first trench 26 prior to forming a sensing oxide layer 32 thereon, more details may refer to the operations later shown in
In some embodiments, a portion of the first gate oxide 30 can be removed in the operation of forming the first trench 26 prior to forming the sensing oxide layer 32 thereon, while another portion of the first gate oxide 30, or called a first gate oxide residue, is adjacent to an edge of the first trench 26, particularly, as shown in the enlarged portion in
In other embodiments, as shown in
As shown in
In some embodiments, the sensing oxide layer 32 is formed over the BEOL structure 20 and in contact with the first surface 16A within the sensing region 22 of the substrate 16. That is, the sensing oxide layer 32 can be formed over the BEOL structure 20 within the logic region 24, while the first trench 26 is formed within the sensing region 22, the structure of the sensing oxide layer 32 is conformal with the profile of first trench 26 to form a sensing trench within the sensing region 22. In some embodiments, the sensing oxide layer 32 comprises hafnium oxide (HfOx). In some embodiments, the thickness of the sensing oxide layer 32 is about 3 µm. In some embodiments, since the inner sidewall of the first trench 26 does not include a continuous planar profile due to an altar of the etching operation in forming the first trench 26, the profile of the sensing oxide layer 32 in the first trench 26 includes at least a change of slope along the inner sidewall of the first trench 26. The details of the method of manufacturing an integrated biosensor structure will be disclosed later.
In some embodiments, the integrated biosensor structure 10 further includes an electrode 60 disposed over the sensing trench, the electrode 60 is configured to be in contact with a medium located in the sensing trench. The sample for sensing in the present disclosure is carried by the medium or be placed directly within the sensing trench and in contact with the sensing oxide layer 32. In some embodiments, the sample is a fluidic biomedical sample, such as DNA containing fluids, blood, interstitial fluid in subcutaneous tissue, muscle or brain tissue, urine, or other body fluids.
In some embodiments, the silicide layer 38 is not formed within the sensing region 22, thus each of the doped regions free from in contact with the sensing oxide layer 32 is covered by a silicide layer 38. That is, silicide is a compound of silicon with metal, and therefore the silicide layer 38 can ensure low contact and series resistance to the source and drain region of the transistor within the logic region 24, whereas the doped regions within the sensing region 22 (i.e., the first doped regions 28) do not need to have conductive contacts and metallization structures thereon, hence there is no silicide layer 38 formed within the sensing region 22.
In some embodiments, within the logic region 24, a metallization structure 40 is formed over the plurality of poly gate structures 34 and the plurality of second doped regions 29. In some embodiments, since the silicide layer 38 is formed to cover the plurality of poly gate structures 34 and the second doped regions 29 within the logic region 24, the conductive contacts of the metallization structure 40 can be landed on the top surface of the silicide layer 38. In some embodiments, the metallization structure 40 includes four metal layers connected by a plurality of conductive vias therebetween, however, the number of the metal layers is not a limitation of the present embodiments.
In some embodiments, the logic region 24 includes a passivation layer 42 formed over the metallization structure 40. The passivation layer 42 may be made of undoped silicate glass (USG), silicon oxynitride, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), fluorinated silicate glass (FSG), organosilicate glasses (OSG), SiOxCy, Spin-On-Glass, or the like. In some embodiments, the passivation layer 42 is formed by high density plasma (HDP), chemical vapor deposition (CVD), plasma-enhanced CVD, sputter, spin-on, physical vapor deposition (PVD), or other applicable methods.
In some embodiments, the sensing oxide layer 32 as previously mentioned can be formed over the passivation layer 42. In some embodiments, the sensing oxide layer 32 is in contact with the passivation layer 42. In some embodiments, the sensing oxide layer 32 in the sensing region 22 extends to the logic region 24 along a side of the metallization structure 40 and a side of the passivation layer 42. In some embodiments, the slope of the side of the first trench 26 (or the slope of the sensing oxide layer 32) is changed due to a change in the etching operations. For example, in forming the first trench 26 that penetrates the passivation layer 42 and the metallization structure 40, an isotropic etching operation can be applied at the very beginning in etching the passivation layer 42 and a portion of the metallization structure 40, and then an anisotropic etching operation can be applied to etch the remained metallization structure 40 to expose the first surface 16A of the substrate 16 within the sensing region 22.
In some embodiments, the integrated biosensor structure 10 includes a second trench 44 over a drain region within the logic region 24. The second trench 44 is leveled with the passivation layer 42 over the logic region 24 of the substrate 16. In some embodiments, the second trench 44 is formed to expose a top of the metallization structure 40 for bumping.
In manufacturing the semiconductor structure as shown in
Next, as shown in
By exposing the first gate structures within the sensing region 22 of the substrate 16, as shown in
As shown in
Then, as shown in
Referring to
Referring to
In some embodiments, the material of the passivation layer 42 is silicon nitride, whereas the material of the ILD 46 is silicon oxide, and thus the profile of the first trench 26 can have a first change point 26A at the interface between the passivation layer 42 and the ILD 46 due to the different etch ratio thereof. In some embodiments, the profile of the first trench 26 can have a second change point 26B at the level of the ILD 46 since the etching technique is changed from a wet etching (or an isotropic) to a dry etching (or an anisotropic). In some embodiments, an amount of the ILD 46 etched by isotropic etching operation is greater than an amount of the ILD 46 etched by anisotropic etching. In some embodiments, most of the first gate oxide 30 can be removed during the dry etching operation. In other words, in some embodiments, the first gate oxide 30 can be preserved at a corner portion of the first trench 26. These first gate oxides 30 are not etched because the boundary of the first trench 26 should be landed over the first gate oxides 30 instead of the field oxides 33; otherwise, the field oxides 33 might be damaged during the etching operation and result in unwanted current leakage. Accordingly, the footing of the first trench 26 should be designed to be landed within the area between the field oxides 33, and a portion of the first gate oxide 30 can thus remain for the buffering purpose. In some embodiments, a side of the first trench 26 is composed of first gate oxide 30, particularly, around the lowermost side of the first trench 26. In some embodiments, the plurality of first doped regions 28 can be exposed by forming the first trench 26.
Referring to
Referring to
In some embodiments, a second surface 16B opposite to the first surface 16A of the substrate 16 is free from having a conductive via in proximity to the second surface 16B. That is, the substrate 16 in the present disclosure is not a portion of an SOI structure that have to be bonded with a handle wafer, thus there are no conductive vias (e.g., TSV) need to be fabricated in proximity to the second surface 16B of the substrate 16. Accordingly, the cost and the yield issues induced by the SOI-based biosensor can be avoided thereby. Meanwhile, since the sensing oxide layer 32 is very close to the source/drain regions within the sensing region 22 of the substrate 16, hence the sensitivity would be better than the FET-based biosensor. Overall, the integrated biosensor structure 10 disclosed in the present disclosure includes the advantages of high sensitivity, low cost, high yield in manufacturing, and entirely capable with the mature CMOS process.
In one exemplary aspect, an integrated biosensor structure is provided. The integrated biosensor structure includes a CMOS structure and a sensing oxide layer. The CMOS structure includes a substrate having a first surface, the substrate includes a sensing region and a logic region surrounding the sensing region; a FEOL structure having a plurality of doped regions at the first surface of the substrate; and a BEOL structure over the FEOL structure. The BEOL structure includes a first trench penetrating the BEOL structure. The sensing oxide layer is disposed over the BEOL structure and in contact with the sensing region of the substrate through the first trench. The sensing oxide layer is conformal with the first trench of the BEOL structure to form a sensing trench.
In another exemplary aspect, an integrated biosensor structure is provided. The integrated biosensor structure includes a substrate having a first surface. The substrate includes a sensing region and a logic region surrounding the sensing region. The sensing region includes a plurality of first doped regions at the first surface of the substrate; and a sensing oxide layer over the plurality of first doped regions. The sensing oxide layer and the first surface of the substrate are free from having a metallization structure there between. The logic region includes a plurality of second doped regions at the first surface of the substrate; a plurality of gate structures over the plurality of second doped regions; and a metallization structure over the plurality of gate structures.
In yet another exemplary aspect, a method of manufacturing an integrated biosensor structure is provided. The method includes the following operations: a substrate having a first gate oxide and a second gate oxide over a first surface of the substrate is received; a plurality of first doped regions and a plurality of second doped regions are formed at the first surface of the substrate; the first gate oxide is thinned down; a silicide layer is formed over the second gate oxide and the plurality of second doped regions; a metallization structure is formed over the plurality of second doped regions, the plurality of first doped regions are covered by a dielectric material of the metallization structure; the dielectric material of the metallization structure is etched to form a first trench to expose the plurality of first doped regions; and a sensing oxide layer is formed over the plurality of first doped regions.
The foregoing outlines structures of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other operations and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
This application claims the benefit of prior-filed U.S. Provisional Application No. 63/313,532, filed Feb. 24, 2022, and incorporates its entirety herein.
Number | Date | Country | |
---|---|---|---|
63313532 | Feb 2022 | US |