KR102421290B1 - Apparatus and method for forming alignment marks - Google Patents

Abstract

An apparatus and method for forming alignment marks are disclosed. The method of forming the alignment marks is a photolithography-free process and includes the following operations. A laser beam is provided. The laser beam is split into a plurality of laser beams separated from each other. The plurality of laser beams are formed of a plurality of patterned beams, and the plurality of patterned beams are formed in a pattern corresponding to the alignment marks. A plurality of patterned beams are projected onto the semiconductor wafer.

Description

Apparatus and method for forming alignment marks

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 62/906,747, filed September 27, 2019. The entirety of the above-mentioned patent applications are incorporated herein by reference and constitute a part of this specification.

Semiconductor manufacturing involves thousands of processes. The photolithography process involves accurately transferring a mask pattern on a mask plate onto a semiconductor wafer. Aligning the mask plate with the semiconductor wafer, including calculating the position of the mask plate relative to the semiconductor wafer, is used to achieve overlay accuracy. Alignment in photolithographic processes is generally achieved using mark alignment. In mark alignment, a first patterned layer has alignment marks disposed therein, and a subsequently formed layer is aligned with the first layer by aligning with the alignment marks.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the present disclosure are best understood from the following detailed description taken together with the accompanying drawings. It should be understood that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.
1 is a schematic top view of a semiconductor wafer having alignment marks in accordance with some embodiments.
2 is a schematic perspective view of an alignment mark forming apparatus according to some embodiments.
3A and 3B illustrate luminous intensity distribution of a laser beam in accordance with some embodiments.
4 is a partially enlarged view of an alignment mark in accordance with some embodiments.
5A and 5B are schematic cross-sectional views of alignment marks in accordance with some embodiments taken along lines AA′ and BB′ illustrated in FIG. 4 , respectively.
6 is a flowchart of a method of forming an alignment mark in accordance with some embodiments.

The following disclosure provides a number of different embodiments or examples for implementation of various different features of the presented subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely several examples and are not intended to be limiting. For example, in the description that follows, the formation of a first feature on a second feature may include embodiments in which the first and second features are formed in direct contact and the first and second features may not be in direct contact. It may also include embodiments in which additional features may be formed between the first and second features. Additionally, this disclosure may repeat reference numbers and/or letters in the various examples. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or configurations being discussed.

In addition, spatial relational terms such as "below" (eg, beneath, below, lower), "above" (eg, on, over, overlying, above, upper), as exemplified herein, other element(s) or It may be used for ease of description that describes the relationship of an element or feature to feature(s). Spatial terminology is intended to include other orientations of the element in use or in operation in addition to the orientations represented in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatial relation descriptors used herein may be interpreted similarly accordingly.

Embodiments will be described in the context of a specific context, ie an apparatus and method for forming alignment marks in a photolithography-free process. The embodiments discussed herein provide examples that make or use the subject matter of the present disclosure, and those skilled in the art will readily appreciate modifications that may be made while remaining within the contemplated scope of different embodiments. In the drawings that follow, like reference numbers and letters refer to like elements. While method embodiments may be discussed as being performed in a particular order, other method embodiments may be performed in any logical order.

1 is a schematic top view of a semiconductor wafer having alignment marks in accordance with some embodiments. Referring to FIG. 1 , a semiconductor wafer (or substrate) 10 is shown, and the semiconductor wafer 10 has a first alignment mark AM1 and a second alignment mark AM2 therein. In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 may be disposed on a peripheral region of the semiconductor wafer 10 . In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 are diagonally symmetric with respect to the center of the semiconductor wafer 10 ; Accordingly, the first alignment mark AM1 and the second alignment mark AM2 are disposed on both sides with respect to the center of the semiconductor wafer 10 . In another embodiment, the first alignment mark AM1 and the second alignment mark AM2 are disposed at different positions (rather than on both sides with respect to the center of the semiconductor wafer 10 ). However, the present disclosure is not limited thereto. In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 are disposed in different regions of the semiconductor wafer 10 such as scribe lines. Although two alignment marks AM1 and AM2 are illustrated in FIG. 1 . In some embodiments, the semiconductor wafer 10 has three or more alignment marks, and the number of alignment marks is not limited.

According to some embodiments, the semiconductor wafer 10 includes a crystalline silicon substrate. According to another embodiment, the semiconductor wafer 10 includes an elemental semiconductor substrate such as germanium; a compound semiconductor substrate comprising silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide and/or indium antimonide; alloy semiconductor substrates comprising SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP and/or GaInAsP; or combinations thereof. Other semiconductor substrates, such as multilayer or gradient substrates, may also be used as semiconductor wafer 10 .

The first alignment mark AM1 is illustrated in an enlarged state as indicated by a dotted line in FIG. 1 . In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 have substantially the same pattern. In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 have different patterns. In some embodiments, the first alignment mark AM1 and the second alignment mark AM2 each consist of four groups of alignment lines of a square. The first alignment mark AM1 and the second alignment mark AM2 are respectively two sets of the first alignment lines 110 arranged in a first direction (eg, Y-direction) and a second direction (eg, X-direction). ), wherein the first direction (eg, Y-direction) is different (eg, perpendicular) to the second direction (eg, X-direction). In some embodiments, the two sets of first alignment lines 110 arranged in the first direction are diagonally symmetrically arranged with respect to the central pattern 130, and the two sets of second alignment lines arranged in the second direction ( 120) is diagonally and symmetrically disposed with respect to the central pattern. In some embodiments, the two sets of first alignment lines 110 arranged in the first direction and the two sets of second alignment lines 120 arranged in the second direction achieve alignment in the first direction and the second direction, respectively. used to achieve

In some embodiments, the first alignment lines 110 do not intersect each other, and the second alignment lines 120 do not intersect each other. In some embodiments, the first alignment lines 110 are substantially parallel to each other and the second alignment lines 120 are substantially parallel to each other. In some embodiments, the first alignment lines 110 have substantially the same width and are arranged at substantially equal intervals, and the second alignment lines 120 have substantially the same width and are arranged at substantially equal intervals. . In some embodiments, the width and spacing of the first alignment line 110 or the second alignment line 120 are varied as needed.

In some embodiments, the center pattern 130 is a cross pattern located at the center of the alignment marks. In some embodiments, the center pattern 130 is a visual center point, or has a different shape, such as a dot pattern or a square pattern other than a cross.

2 is a schematic perspective view of an alignment mark forming apparatus according to some embodiments. Referring to FIG. 2 , an apparatus 200 for forming alignment marks AM1 and AM2 on a semiconductor wafer 10 is provided. In some embodiments, the apparatus 200 includes a light source 210 , a beam splitting element 220 , a pattern forming element 230 , and a projection lens 240 . In some embodiments, the light source 210 is configured to emit a laser beam LB.

In some embodiments, the beam splitting element 220 is disposed on the transmission path of the laser beam LB and is disposed on the light propagation path between the light source 210 and the pattern forming element 230 . In some embodiments, the beam splitting element 220 is configured to split the laser beam LB into a plurality of laser beams separated from each other. In some embodiments, the beam splitting element 220 is configured to split the laser beam LB into at least a first laser beam LB1 and a second laser beam LB2 .

In some embodiments, the pattern forming element 230 is disposed on a transmission path of a plurality of laser beams, such as the first laser beam LB1 and the second laser beam LB2 , the beam splitting element 220 and the projection lens It is disposed on the light propagation path between 240 . In some embodiments, the pattern forming element 230 is configured to form the first laser beam LB1 and the second laser beam LB2 into the first patterned beam PB1 and the second patterned beam PB2 . .

In some embodiments, projection lens 240 is disposed on a transmission path of a plurality of patterned beams, such as first patterned beam PB1 and second patterned beam PB2 , and includes pattern forming element 230 and It is disposed on the light propagation path between the semiconductor wafers (10). In some embodiments, the projection lens 240 projects a plurality of patterned beams onto the semiconductor wafer 10 to project a plurality of alignment marks AM1 and second alignment marks AM2 illustrated in FIG. 1 , such as AM2 . configured to directly form an alignment mark.

When the first patterned beam PB1 and the second patterned beam PB2 are irradiated to the semiconductor wafer 10 , a groove G (illustrated in FIGS. 5A and 5B ) is formed. The first patterned beam PB1 and the second patterned beam PB2 may simultaneously ablate or melt the semiconductor wafer 10 to directly form the groove G. In some embodiments, a plurality of grooves G extend from the top surface 10a (illustrated in FIGS. 5A and 5B ) of the semiconductor wafer 10 toward the interior of the semiconductor wafer 10 . In some embodiments, the groove (G) is the first alignment mark (AM1) and the second alignment mark (AM2) in the semiconductor wafer 10, respectively, the alignment line 110, the second alignment line 120, and the center pattern ( 130) is formed.

The first alignment mark AM1 and the second alignment mark AM2 are directly formed by a single laser process. Thereby, various procedures for forming the alignment marks, for example, photoresist coating, baking, exposure and development processes, as well as various procedures such as etching and cleaning processes, are not required. The method of forming alignment marks according to some embodiments of the present disclosure does not include an expensive and time-consuming photolithography process. The methods of forming alignment marks of the present disclosure are referred to in some examples as “photolithography-free” or “chemical-free” processes. A chemical-free process is a process that does not use an etching solution or etching gas. Consequently, the manufacturing process of the alignment mark is simplified and the manufacturing cost is reduced.

In some embodiments, the light source 210 comprises, for example, an excimer laser with a wavelength of 308 nm. In some embodiments, the laser beam LB has a laser energy density of about 18 J/cm ² or greater. As long as the first patterned beam PB1 and the second patterned beam PB2 formed from the laser beam LB can melt the semiconductor wafer 10 to form the alignment marks AM1 and AM2, the present disclosure The content does not limit the wavelength and/or laser energy density of the light source.

In some embodiments, the beam splitting element 220 allows a portion of the laser beam LB to pass through and reflects the remaining portion of the laser beam LB, so that the first laser beam LB1 projecting in different directions is separated from each other. ) and the second laser beam LB2. In some embodiments, the beam splitting element 220 allows half of the laser beam LB to pass through and reflects half of the laser beam LB, so that the luminosity of the first laser beam LB1 is reduced to the second laser beam ( It is substantially equal to the luminosity of LB2). In some embodiments, beam splitting element 220 includes a beam splitter formed of two prisms. In some embodiments, the beam splitting element 220 comprises a beam splitter made of an optically coated glass sheet. In some embodiments, beam splitting element 220 includes two or more beam splitters, each beam splitter splits an incident beam into two components, so beam splitting element 220 splits laser beam LB into three Split into more than one laser beam to form three or more alignment marks. Embodiments in which beam splitting element 220 includes one or more other optical elements capable of splitting an incident beam into a plurality of components are also contemplated herein.

In some embodiments, the pattern forming element 230 forms the first laser beam LB1 and the second laser beam LB2 into the first patterned beam PB1 and the second patterned beam PB2, respectively, The first patterned beam PB1 and the second patterned beam PB2 are formed in patterns corresponding to the first and second alignment marks AM1 and AM2 . In some embodiments, the pattern forming element 230 includes a diffractive optical element (DOE), the diffractive optical element having a specially designed microstructure such that the first patterned beam PB1 and the second patterned beam PB2 to achieve a specific pattern of In some embodiments, a diffractive optical element comprising, for example, a multilevel diffraction grating of 16 or more levels is used to function as the pattern forming element 230 . In some embodiments, the pattern forming element 230 includes a reticle, the reticle including a pattern thereon corresponding to the first alignment mark AM1 and the second alignment mark AM2 . It should be noted that the pattern of the first patterned beam PB1 or the second patterned beam PB2 refers to the pattern of light spots of the first patterned beam PB1 or the second patterned beam PB2 . In some embodiments, the pattern of the first patterned beam PB1 is the same as the pattern of the second patterned beam PB2 . In some alternative embodiments, the pattern of the first patterned beam PB1 is different from the pattern of the second patterned beam PB2 .

In some embodiments, projection lens 240 includes one or more optical lenses having diopters. The present disclosure provides that a first patterned beam PB1 and a second patterned beam PB2 are projected at a desired location on the semiconductor wafer 10 through a projection lens 240 to form alignment marks AM1 and AM2. As far as possible, the type of projection lens 240 is not interpreted.

3A and 3B illustrate the luminous intensity distribution of a laser beam according to some embodiments, wherein the highest luminous intensity corresponds to a central region of a light spot of the laser beam, and the lowest luminous intensity corresponds to a peripheral region of the laser beam. 2 , 3A and 3B , in some embodiments, the apparatus 200 further includes a homogenizer 250 . In some embodiments, homogenizer 250 is disposed on the light propagation path between light source 210 and beam splitting element 220 .

In some embodiments, the laser beam LB emitted from the light source 210 has a luminous intensity distribution similar to a Gaussian distribution as illustrated in FIG. 3A . The luminosity of a Gaussian distribution is higher in the center and lower on both sides. In some embodiments, the laser beam LB emitted from the light source 210 has a non-uniform luminous intensity distribution with two long and elongated tails T on two sides for each light point of the laser beam. The long, elongated tail T of the Gaussian distribution has a luminous intensity slightly lower than the ablation critical intensity TH for melting the semiconductor wafer 10 . The long, elongated tail T of the original laser beam LB causes the profile of the formed groove of the alignment mark to deviate significantly from its intended shape, dimension or roughness. The alignment marks formed may be damaged and fail to provide an alignment function.

In some embodiments, homogenizer 250 is configured to homogenize (or homogenize) laser beam LB. When the laser beam LB passes through the homogenizer 250, the laser beam LB is homogenized, so that the luminous intensity distribution of the laser beam LB is a top-hat as illustrated in FIG. 3B . can be converted into a distribution. The top-hat distribution has a substantially uniform luminous intensity for each light point of the laser beam. After the laser beam LB is homogenized by the homogenizer 250, the light spot of the homogenized laser beam has a luminous intensity distribution similar to the top-hat distribution as illustrated in FIG. 3B . The top-hat distribution may have a substantially uniform luminous intensity distribution with two rapidly decaying tails T on two sides of each light spot of the laser beam. The substantially uniform luminous intensity of the top-hat distribution is higher than the ablation critical strength TH for melting the semiconductor wafer 10 . The short tail (T) of the top-hat distribution has a luminosity much lower than the ablation threshold intensity (TH) for melting of the semiconductor wafer 10 . This short, weak tail T of the luminous intensity distribution may cause the profile of the grooves of the alignment marks AM1 , AM2 to be slightly rounded at the ends and/or slightly roughened at the sidewalls, which is related to Figs. 4 and 5a-5b. discussed in the description. The formed alignment marks may provide an alignment function.

The luminous intensity distribution of the laser beam LB becomes uniform after passing through the homogenizer 250 . Thereby, the undesirable profile and bottom damage of the groove G of the first alignment mark AM1 and the second alignment mark AM2 are reduced, and thus the process window for forming the alignment marks AM1 and AM2 is reduced. is increased In some embodiments, homogenizer 250 includes a rod integrator. In some embodiments, the homogenizer 250 is arranged along the optical axis of the laser beam LB. In some embodiments, homogenizer 250 has a rectangular light incident surface and a rectangular light exit surface. After the incident laser beam LB is incident on the light incident surface of the homogenizer 250 , multiple reflections of the laser beam LB occur in the homogenizer 250 to obtain homogenization of the laser beam LB. . In some embodiments, the reflection is total reflection. In some embodiments, homogenizer 250 includes a diffractive optical element (DOE).

In some embodiments, device 200 further includes one or more optical elements to achieve a particular optical function. In some embodiments, the apparatus 200 further includes an optical isolator 260 , a beam expander 270 , reflective elements RE1 , RE2 , RE3 , RE4 , and/or lenses L1 , L2 , L3 , L4 . . In some embodiments, the optical isolator 260 is disposed between the light source 210 and the beam expander 270 . In some embodiments, the optical isolator 260 is configured to allow the laser beam LB to be transmitted in only one direction to prevent a portion of the laser beam LB from returning back to the light source 210 . In some embodiments, beam expander 270 is disposed on the light propagation path between optical isolator 260 and homogenizer 250 . In some embodiments, the beam expander 270 expands the laser beam LB such that the laser beam LB is converted from point light to surface light. After the laser beam LB passes through the beam expander 270 , the width of the laser beam LB increases, and the area of the light spot of the laser beam LB becomes larger. In some embodiments, beam expander 270 is coated with an anti-reflective coating to reduce optical loss.

In some embodiments, the reflective elements RE1 , RE2 , RE3 , RE4 are configured to steer the optical path of the laser beam LB, ie the first laser beam LB1 or the second laser beam LB2 . For example, the reflective elements RE1 and RE2 project (reflect) the laser beam LB emitted from the beam expander 270 to the homogenizer 250, and the reflective elements RE3 are the homogenizer 250. It projects (reflects) the laser beam LB from the beam splitting element 220 . The reflective element RE4 redirects the second laser beam LB2 emitted from the beam splitting element 220 to project (reflect) the second laser beam LB2 to the pattern forming element 230 , so that the second The laser beam LB2 may be projected in the same direction as the first laser beam LB1 . In some embodiments, lens L1 , L2 between reflective elements RE1 , RE2 , lens L3 between beam splitting element 220 and pattern forming element 230 , and reflective element RE4 with pattern forming element The lens L4 between 230 is configured to converge or collimate the laser beam LB, that is, the first laser beam LB1 and the second laser beam LB2, respectively. In some embodiments, beam expander 270 , pattern forming element 230 and/or semiconductor wafer 10 are disposed on a focal plane of apparatus 200 .

4 is a partially enlarged view of an alignment mark in accordance with some embodiments. 5A and 5B are schematic cross-sectional views of alignment marks in accordance with some embodiments taken along lines A-A′ and B-B′ illustrated in FIG. 4 , respectively; As illustrated in FIG. 4 , in some embodiments, since the first and second alignment marks AM1 and AM2 are formed by the above-described laser process, the first and second alignment marks AM1 and AM2 The first and second alignment lines 110 and 120 may have a tapered end TE, and the first and second alignment lines 110 and 120 of the first and second alignment marks AM1 and AM2 may have tapered ends TE. It may have a residue RS protruding from the sidewall SW. In some embodiments, the width of the central portion of one first alignment line 110 or second alignment line 120 is equal to the tapered end TE of the first alignment line 110 or second alignment line 120 . ) is wider than the width of In some embodiments, a pump (not shown) is provided to remove byproducts of laser ablation from the semiconductor wafer 10 . In some embodiments, the residue RS remains on the top surface of the semiconductor wafer 10 . The residue RS remains on the top surface and/or sidewall of at least one of the first alignment line 110 or the second alignment line 120 . It should be noted that although some residues RS are present, these residues RS are usually too small to affect the alignment function of the first and second alignment marks AM1, AM2. In some embodiments, the sidewall SW of the first and second alignment lines 110 and 120 of the first and second alignment marks AM1 and AM2 has a surface roughness Rz in a range of about 2 nm to about 50 nm is provided In some embodiments, the surface roughness (Rz) is calculated by measuring the vertical distance from the highest peak to the lowest valley within a predetermined sampling length or region.

As illustrated in FIGS. 5A and 5B , in some embodiments, the first and second alignment lines 110 and 120 of the first and second alignment marks AM1 and AM2 are in the groove G with an inclined sidewall ( SW). In some embodiments, each of the first and second alignment lines 110 and 120 has an upper width W1 greater than a lower width W2 . The included angle θ is an acute angle between the inclined sidewall SW and the upper surface 10a of the semiconductor substrate 10 . In some embodiments, the included angle θ between each of the first and second alignment lines 110 , 120 and the substrate 10 ranges from about 30 degrees to about 75 degrees. In some embodiments, the included angle θ between each of the first and second alignment lines 110 , 120 and the substrate 10 is about 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees. , 60 degrees, 65 degrees, 70 degrees, 75 degrees, any range between any two of the preceding values, or any range less than any value of any one of the preceding values. In the present disclosure, in the "photolithography-free" or "chemical-free" process described above, each alignment line of the alignment marks formed in this angular range (30-75 degrees) can satisfy the process requirements, The manufacturing process is simplified and the manufacturing cost is reduced.

In the cross-sectional view, the inclined sidewall SW at a position close to the upper and/or lower portion of at least one of the first and second alignment lines 110 and 120 may be curved or rounded. In some embodiments, at least one groove G between adjacent first alignment lines 110 or second alignment lines 120 is formed between the inclined sidewall SW of the semiconductor wafer 10 and the upper surface 10a. It has rounded bottom corners.

6 is a flow diagram of a method 300 for forming an alignment mark in accordance with some embodiments. Although the method 300 is illustrated and/or described as a series of acts or events, it will be understood that the method is not limited to the illustrated order or acts. Accordingly, in some embodiments, the operations may be performed in an order other than that illustrated and/or may be performed concurrently. Further, in some embodiments, an illustrated action or event may be subdivided into multiple actions or events, which may be performed at separate times or concurrently with respect to other actions or sub-actions. In some embodiments, some illustrated actions or events may be omitted, and other actions or events not illustrated may be included.

In operation 302 , a laser beam is provided. 2 illustrates a light source 210 configured to provide a laser beam LB. In some embodiments, the laser beam LB is an excimer laser beam. In some embodiments, the laser beam LB has a luminous intensity distribution similar to a Gaussian distribution as illustrated in FIG. 3A .

In operation 304, the laser beam is homogenized. 2 illustrates a homogenizer 250 configured to homogenize (or equalize) the laser beam LB. In some embodiments, after the laser beam LB is homogenized, the laser beam LB has a luminous intensity distribution similar to the top-hat distribution as illustrated in FIG. 3B . In some embodiments, the laser beam LB is homogenized by a rod integrator. In some embodiments, the laser beam LB is homogenized by a diffractive optical element DOE.

In operation 306, the laser beam is split into a plurality of laser beams. 2 illustrates a beam splitting element 220 configured to split the laser beam LB into a first laser beam LB1 and a second laser beam LB2 separated from each other. In some embodiments, the beam splitting element 220 passes half of the laser beam LB and reflects half of the laser beam LB so that the luminous intensity of the first laser beam LB1 and the second laser beam LB2 is Practically the same.

In some embodiments, operation 306 is performed after operation 304. In some embodiments, operation 306 is performed prior to operation 304 . For example, the laser beam LB emitted from the light source 210 is first split into a first laser beam LB1 and a second laser beam LB2 , and then a first laser beam LB1 and a second laser beam (LB2) is homogenized by the first homogenizer and the second homogenizer, respectively.

In operation 308 , the plurality of laser beams are formed into a plurality of patterned beams. 2 illustrates a pattern forming element 230 configured to form a first laser beam LB1 and a second laser beam LB2 into a first patterned beam PB1 and a second patterned beam PB2, respectively. . In some embodiments, the first patterned beam PB1 and the second patterned beam PB2 are formed in a pattern corresponding to the first alignment mark AM1 and the second alignment mark AM2 . In some embodiments, the first laser beam LB1 and the second laser beam LB2 are formed by a diffractive optical element DOE. In some embodiments, the first laser beam LB1 and the second laser beam LB2 are formed by a reticle.

In operation 310 , a plurality of patterned beams are projected onto the semiconductor wafer. 2 shows a first patterned beam PB1 and a second patterned beam PB2 to be projected onto a semiconductor wafer 10 to directly form a first alignment mark AM1 and a second alignment mark AM2. A configured projection lens 240 is illustrated. In some embodiments, the first patterned beam PB1 and the second patterned beam PB2 direct the first alignment of the first alignment mark AM1 and the second alignment mark AM2 to the semiconductor wafer 10 , respectively. The semiconductor wafer 10 is ablated to form the line 110 , the second alignment line 120 , and the central pattern 130 .

In consideration of the above, with the method of the embodiment of the present disclosure, the first alignment mark AM1 and the second alignment mark AM2 are directly formed by a single laser process. Thus, various procedures for forming the alignment marks, for example, photoresist coating, baking, exposure and development processes, as well as various procedures such as etching and cleaning processes, are not required. A method of forming alignment marks in accordance with some embodiments of the present disclosure is a photolithography-free process. Consequently, the manufacturing process of the alignment mark is simplified and the manufacturing cost is reduced.

The above embodiments of providing an apparatus and method for forming an alignment mark are provided for purposes of illustration and should not be construed as limiting the present disclosure. In some embodiments, apparatus and methods are provided for forming other marks, such as wafer identification (ID). In some embodiments, the wafer's alignment marks and wafer identification are simultaneously produced by a single laser exposure and melting process.

According to some embodiments of the present disclosure, a method of forming an alignment mark includes several operations. A laser beam is provided. The laser beam is split into a plurality of laser beams separated from each other. The plurality of laser beams are formed of a plurality of patterned beams, and the plurality of patterned beams are formed in a pattern corresponding to the alignment marks. A plurality of patterned beams are projected onto the semiconductor wafer.

According to an alternative embodiment of the present disclosure, a method of forming an alignment mark includes several operations. A light source is provided to emit a laser beam. A laser splitter is provided to split the laser beam into a first laser beam and a second laser beam traveling in different directions. A reflective element is provided to redirect one of the first laser beam and the second laser beam, the first laser beam and the second laser beam traveling in the same direction. A pattern forming element is provided to form the first laser beam and the second laser beam into the first patterned beam and the second patterned beam, the patterns of the first patterned beam and the second patterned beam correspond to the alignment marks . A projection lens is provided to project the first patterned beam and the second patterned beam onto the semiconductor wafer to directly form the alignment marks.

According to another embodiment of the present disclosure, an apparatus includes a light source, a beam splitting element, a pattern forming element and a projection lens. The light source is configured to emit a laser beam. The beam splitting element is configured to split the laser beam into a plurality of laser beams separated from each other. The pattern forming element is configured to form the plurality of laser beams into the plurality of patterned beams. The projection lens is configured to project a plurality of patterned beams onto the semiconductor wafer to form a plurality of alignment marks.

According to another embodiment of the present disclosure, the alignment mark includes two first sets of alignment lines and two second sets of alignment lines. The two first sets of alignment lines are arranged in a first direction and arranged diagonally and symmetrically with respect to the central pattern. The two second sets of alignment lines are arranged in a second direction different from the first direction and arranged diagonally and symmetrically with respect to the central pattern. The first and second alignment lines have tapered ends.

The above description has outlined features of various embodiments in order that those skilled in the art may better understand the various 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 processes or structures for carrying out the same purposes and/or achieving the same advantages as the embodiments introduced herein. In addition, those skilled in the art should appreciate that equivalent constructions may make various changes, substitutions and alterations without departing from the spirit and scope of the present disclosure and without departing from the spirit and scope of the present disclosure.

<Note>

1. A method of forming an alignment mark, comprising:

providing a laser beam;

dividing the laser beam into a plurality of laser beams separated from each other;

shaping the plurality of laser beams into a plurality of patterned beams having patterns shaped to correspond to the alignment marks; and

projecting the plurality of patterned beams onto a semiconductor wafer;

A method of forming an alignment mark comprising a.

2. The method of claim 1, wherein the method is a photolithography-free process.

3. The method of clause 1, wherein the plurality of laser beams are shaped by a reticle.

4. The method of clause 1, wherein the plurality of laser beams are shaped by a diffractive optical element (DOE).

5. The method of clause 1, further comprising homogenizing the laser beam prior to splitting the laser beam into the plurality of laser beams.

6. The method according to claim 5, wherein after the laser beam is homogenized, the laser beam has a top-hat intensity distribution.

7. The method of clause 1, wherein each of the plurality of laser beams has the same light intensity.

8. The method of clause 1, further comprising removing a by-product from the semiconductor wafer.

9. A method of forming an alignment mark comprising:

providing a light source to emit a laser beam;

providing a beam splitter to split the laser beam into a first laser beam and a second laser beam traveling in different directions;

providing a reflective element to redirect at least one of the first laser beam and the second laser beam such that the first laser beam and the second laser beam travel in the same direction;

providing a pattern forming element to shape the first laser beam and the second laser beam into a first patterned beam and a second patterned beam, the pattern of the first patterned beam and the second patterned beam comprising: corresponding to the alignment mark; and

providing a projection lens to project the first patterned beam and the second patterned beam onto a semiconductor wafer to directly form the alignment mark;

A method of forming an alignment mark comprising a.

10. The method of claim 9, wherein providing a beam splitter comprises providing a reticle.

11. The method of claim 9, wherein providing a beam splitter comprises providing a diffractive optical element (DOE).

12. Item 9,

and providing a homogenizer to homogenize the laser beam prior to providing the beam splitter to split the laser beam into the first laser beam and the second laser beam.

13. The method of clause 9, wherein the intensity of the first laser beam is substantially equal to the intensity of the second laser beam.

14. The method of claim 9, wherein the method is a chemical free process.

15. Item 9,

and providing a pump to remove byproducts accompanying the formation of the alignment marks from the semiconductor wafer.

16. As an alignment mark,

two sets of first alignment lines arranged in a first direction and arranged diagonally and symmetrically with respect to the central pattern; and

two sets of second alignment lines arranged in a second direction different from the first direction and arranged diagonally and symmetrically with respect to the central pattern

including,

and the first alignment line and the second alignment line have a tapered end.

17. The alignment mark of clause 16, wherein the alignment mark is formed by a process without photolithography.

18. The alignment mark of clause 16, wherein the first and second alignment lines have a residue projecting from their sidewalls.

19. The alignment mark of item 18, wherein the surface roughness of the sidewalls of the first and second alignment lines is in the range of about 2 nm to about 50 nm.

20. The alignment mark of clause 18, wherein the included angle between each of the first and second alignment lines and the substrate is in the range of about 30 degrees to about 75 degrees.

Claims (10)

A method of forming an alignment mark comprising:
providing a laser beam;
dividing the laser beam into a plurality of laser beams separated from each other, the plurality of laser beams including a first laser beam and a second laser beam;
shaping the plurality of laser beams into a plurality of patterned beams, the plurality of patterned beams comprising a first patterned beam and a second patterned beam; and
projecting the plurality of patterned beams onto a semiconductor wafer;
includes,
The alignment marks include two sets of first alignment lines arranged in a first direction and arranged diagonally symmetrically with respect to the central pattern and diagonally symmetrical with respect to the central pattern and arranged in a second direction different from the first direction. two sets of second alignment lines arranged as
the pattern of the first patterned beam corresponds to the first alignment line, and the pattern of the second patterned beam corresponds to the second alignment line;
wherein the first alignment line and the second alignment line have a tapered end when viewed from a top view of the semiconductor wafer. The method of claim 1 , wherein the method is a photolithography-free process. The method of claim 1 , wherein the plurality of laser beams are shaped by a reticle. The method of claim 1 , wherein the plurality of laser beams are shaped by a diffractive optical element (DOE). The method of claim 1 , further comprising homogenizing the laser beam prior to splitting the laser beam into the plurality of laser beams. 6. The method of claim 5, wherein after the laser beam is homogenized, the laser beam has a top-hat intensity distribution. The method of claim 1 , wherein each of the plurality of laser beams has the same light intensity. The method of claim 1 , further comprising removing a by-product from the semiconductor wafer. A method of forming an alignment mark comprising:
providing a light source to emit a laser beam;
providing a beam splitter to split the laser beam into a first laser beam and a second laser beam traveling in different directions;
providing a reflective element to redirect at least one of the first laser beam and the second laser beam such that the first laser beam and the second laser beam travel in the same direction;
providing a pattern forming element to shape the first laser beam and the second laser beam into a first patterned beam and a second patterned beam; and
providing a projection lens to project the first patterned beam and the second patterned beam onto a semiconductor wafer to directly form the alignment mark;
includes,
The alignment marks include two sets of first alignment lines arranged in a first direction and arranged diagonally symmetrically with respect to the central pattern and diagonally symmetrical with respect to the central pattern and arranged in a second direction different from the first direction. two sets of second alignment lines arranged as
the pattern of the first patterned beam corresponds to the first alignment line, and the pattern of the second patterned beam corresponds to the second alignment line;
wherein the first alignment line and the second alignment line have a tapered end when viewed from a top view of the semiconductor wafer. An alignment mark formed on the inside of a semiconductor wafer, comprising:
two sets of first alignment lines arranged in a first direction and arranged diagonally and symmetrically with respect to the central pattern; and
two sets of second alignment lines arranged in a second direction different from the first direction and arranged diagonally and symmetrically with respect to the central pattern
including,
and the first alignment line and the second alignment line have a tapered end when viewed from a top view of the semiconductor wafer.

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