METHOD FOR JOINING A SEMICONDUCTOR SUBSTRATE

Abstract

A method for bonding semiconductor substrates, comprising: Forming an alignment key on a first semiconductor substrate; Forming a first protrusion and a second protrusion and an alignment recess positioned between the first protrusion and the second protrusion on a second semiconductor substrate; Forming a first metal layer and a second metal layer on the first projection and the second projection, respectively; and Connecting the first semiconductor substrate and the second semiconductor substrate, wherein the alignment key is positioned at the alignment recess when the first semiconductor substrate and the second semiconductor substrate are bonded.

Description

BACKGROUND(a) Field of the InventionThe present invention relates to a method for bonding semiconductor substrates.(b) Description of Related ArtGenerally, a metal layer and an insulating layer are deposited or a micropattern is formed on a semiconductor substrate to form a semiconductor device. The semiconductor device may also be formed by bonding two or more semiconductor substrates on which a thin film layer such as the metal layer and the insulating layer and the micropattern are formed.Semiconductor substrate means a substrate obtained by growing a starting material of a semiconductor and single-crystallising (single-crystallising) the starting material of the semiconductor like a rod, thin punching the single-crystallised (singularlycrystallized) starting material of the semiconductor according to the crystal orientation and grinding and polishing the punched semiconductor starting material, and is also referred to as a wafer.When two or more semiconductor substrates are bonded, an error generated during the alignment of the semiconductor substrates must be taken into account. In general, in alignment of semiconductor substrates, alignment keys (alignment keys) formed in the semiconductor substrates are adjusted using an optical measurement method to connect the semiconductor substrates. However, in this case, a fine defect may be generated. Further, an alignment error may be generated by thermal expansion during a plurality of joining processes or a metal layer may flow back due to heat or pressure during joining, so that a defect may be generated.US 2003 / 0042602 A1 describes a conventional approach for connecting semiconductor substrates by forming an alignment key on a first semiconductor substrate, an alignment recess situated between two projections on a second semiconductor substrate and a metal layer on the two projections in each case. In later bonding the semiconductor substrates, the alignment key is positioned in the alignment recess.Another conventional approach for connecting semiconductor substrates is disclosed in US 2008 / 0305410 A1.The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore may contain information that does not form the prior art already known to those of ordinary skill in the art.SUMMARYThe present invention is directed to preventing a metal layer from flowing back in connecting semiconductor substrates in which the metal layer is formed.The present invention provides a method of bonding semiconductor substrates having the features of claim 1.A thickness of the alignment key may be greater than a thickness of the first metal layer and second metal layer.The forming of the first protrusion, the second protrusion, and the alignment groove may include: forming a first photosensitive film pattern on the second semiconductor substrate; and etching the second semiconductor substrate using the first photosensitive film pattern as a mask.The forming of the first metal layer and the second metal layer may include: forming a second photosensitive film pattern on the second semiconductor substrate except for the first protrusion and the second protrusion; forming a metal layer on the second photosensitive film pattern, the first protrusion, and the second protrusion; and removing the second photosensitive film pattern and the metal layer positioned on the second photosensitive film pattern by performing a lift-off process.The method may further include forming an insulating layer on the first semiconductor substrate before forming the alignment key.As described above, according to the exemplary embodiment of the present invention, the alignment key is positioned at the alignment recess when the first semiconductor substrate and the second semiconductor substrate are bonded, and thereby bonds the first semiconductor substrate and the second semiconductor substrate without an alignment error.Further, a thickness of the alignment key may be greater than a thickness of the metal layers, which prevents the metal layers from flowing back and down to be bonded together when the first semiconductor substrate and the second semiconductor substrate are bonded.BRIEF DESCRIPTION OF THE DRAWINGSFIGS. 1 to 6 are cross-sectional views illustrating a process for connecting semiconductor substrates according to an exemplary embodiment of the present invention.DETAILED DESCRIPTION OF THE EMBODIMENTSExemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The exemplary embodiments disclosed herein are provided so that the disclosed contents will be thorough and complete, and the spirit of the present invention can be sufficiently understood by those skilled in the art.In the drawings, the thickness of layers and regions is exaggerated for clarity. In addition, in the case where it is mentioned that a layer is present "on" the other layer or a substrate, the layer may be formed directly on the other layer or the substrate or a third layer may be interposed therebetween. Throughout the specification, like reference numerals designate like components.It will be understood that the term "vehicle" or "vehicular" or other similar term as used herein includes motor vehicles in general such as passenger automobiles including off-road vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle having two or more sources of power, such as both gasoline-powered and electric-powered vehicles.The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a / an" and "the / s" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one / more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.A process for connecting semiconductor substrates according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 6.Hereinafter, a process for connecting two semiconductor substrates in the present exemplary embodiment will be described. However, the present invention is not limited thereto, and three or more semiconductor substrates may be bonded by the bonding method.FIGS. 1 to 6 are cross-sectional views illustrating a process for connecting semiconductor substrates according to an exemplary embodiment of the present invention.Referring to FIG. 1, a first semiconductor substrate 100 is prepared, and then an insulating layer 110 is formed on the first semiconductor substrate 100, and an alignment key 120 is formed.The insulating layer 110 may be formed of an insulating material such as silicon oxide (SiO 2). The alignment key 120 may be formed of a photosensitive polymeric material. For example, the alignment key 120 may be formed by forming a photosensitive polymer material layer on the insulating layer 110 using a photosensitive polymer material and then etching the photosensitive polymer material layer. As described above, the alignment key 120 is formed using a light-sensitive polymer material, and thereby the alignment key 120 is easily formed.Referring to FIGS. 2 and 3, a second semiconductor substrate 200 is prepared, and then a first photosensitive film pattern 50 is formed on the second semiconductor substrate 200, and the second semiconductor substrate 200 is etched using the first photosensitive film pattern 50 as a mask. The etching may be performed by dry etching or wet etching.By the etching, an alignment groove 210, a first protrusion 211, and a second protrusion 212 are formed on the second semiconductor substrate 200. The alignment recess 210 is positioned between the first protrusion 211 and the second protrusion 212.Referring to FIG. 4, after a second photosensitive film pattern 60 is formed on the second semiconductor substrate 200, a metal layer 220 is formed on the second semiconductor substrate 200 and the second photosensitive film pattern 60.Specifically, the second photosensitive film pattern 60 is not formed in the first protrusion 211 and the second protrusion 212 of the second semiconductor substrate 200. Consequently, only the metal layer 220 is formed on the first protrusion 211 and the second protrusion 212 of the second semiconductor substrate 200.Referring to FIG. 5, the second photosensitive film pattern 60 is removed from the second semiconductor substrate 200 by a lift-off process. In this case, the metal layer 220 positioned on the second photosensitive film pattern 60 is also removed. Consequently, a first metal layer 221 and a second metal layer 222 are formed on the first protrusion 211 and the second protrusion 212 of the second semiconductor substrate 200, respectively.According to the present exemplary embodiment, the first metal layer 221 and the second metal layer 222 are formed by the lift-off process without using a mask, but the present invention is not limited thereto, and the first metal layer 221 and the second metal layer 222 may also be formed using a mask. For example, after the metal layer 220 is formed on the second semiconductor substrate 200 without forming the second photosensitive film pattern 60, the first metal layer 221 and the second metal layer 222 may be formed by etching the metal layer 220 using a mask.Referring to FIG. 6, the first semiconductor substrate 100 and the second semiconductor substrate 200 are connected. In this case, the alignment key 120 positioned in the first semiconductor substrate 100 is positioned at the alignment recess 210 of the second semiconductor substrate 200. As described above, when the first semiconductor substrate 100 and the second semiconductor substrate 200 are bonded, the alignment key 120 is positioned at the alignment recess 210, thereby bonding the first semiconductor substrate 100 and the second semiconductor substrate 200 without an alignment error.Meanwhile, a thickness of the alignment key 120 according to the present exemplary embodiment is greater than a thickness of the first metal layer 221 and the second metal layer 222.When the first semiconductor substrate 100 and the second semiconductor substrate 200 are bonded, heat and pressure are generated. The first metal layer 221 and the second metal layer 222 may flow back and down by the heat and the pressure. In this case, the first metal layer 221 and the second metal layer 222 of the reflux may flow down to be joined to each other.However, in the present exemplary embodiment, since the alignment key 120 is positioned in the alignment recess 210 disposed between the first protrusion 211 and the second protrusion 212 and the thickness of the alignment key 120 is greater than the thickness of the first metal layer 221 and the second metal layer 222, the first metal layer 221 and the second metal layer 22 can be prevented from being joined to each other even when the first metal layer 221 and the second metal layer 222 flow back and down. Consequently, when the semiconductor device is formed by connecting the first semiconductor substrate 100 and the second semiconductor substrate 200, it is possible to prevent a defect of the semiconductor device.Meanwhile, a plurality of semiconductor devices may be generally formed in the semiconductor substrate. Consequently, a plurality of alignment keys 110 may be formed in the first semiconductor substrate 100. Further, a plurality of alignment recesses 210 corresponding to the alignment keys 120 may also be formed in the second semiconductor substrate 200.As mentioned above, the process for bonding the two semiconductor substrates is described in the present exemplary embodiment, but the present invention is not limited thereto, and three or more semiconductor substrates may be bonded by the aforementioned bonding method. For example, another alignment groove is formed on an opposite surface of a portion where the alignment groove 210 of the second semiconductor substrate 200 is formed, and then another substrate (for example, a third semiconductor substrate) where an alignment key and a metal layer are formed may be bonded to the second semiconductor substrate 200. In this case, the alignment key of the third semiconductor substrate is positioned at another alignment recess of the second semiconductor substrate 200.

Claims

A method of connecting semiconductor substrates, comprising: forming an alignment key on a first semiconductor substrate; forming a first protrusion and a second protrusion and an alignment recess positioned between the first protrusion and the second protrusion on a second semiconductor substrate; forming a first metal layer and a second metal layer on the first protrusion and the second protrusion, respectively; and connecting the first semiconductor substrate and the second semiconductor substrate, wherein the alignment key is positioned at the alignment recess when the first semiconductor substrate and the second semiconductor substrate are connected.The method of claim 1, wherein: a thickness of the alignment key is greater than a thickness of the first metal layer and the second metal layer.The method of claim 2, wherein: the alignment key is formed from a photosensitive polymeric material.The method of claim 1, wherein: forming the first protrusion, the second protrusion, and the alignment recess includes: forming a first photosensitive film pattern on the second semiconductor substrate; and etching the second semiconductor substrate using the first photosensitive film pattern as a mask.The method of claim 4, wherein: forming the first metal layer and the second metal layer includes: forming a second photosensitive film pattern on the second semiconductor substrate except for the first protrusion and the second protrusion; forming a metal layer on the second photosensitive film pattern, the first protrusion, and the second protrusion; and removing the second photosensitive film pattern and the metal layer positioned on the second photosensitive film pattern by performing a lift-off process.The method of claim 1, further comprising: forming an insulating layer on the first semiconductor substrate prior to forming the alignment key.

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