BACKGROUND
1. Technical Field
Aspects of this document relate generally to semiconductor substrates. More specific implementations involve silicon-on-insulator (SOI) substrates.
2. Background
Silicon-on-insulator (SOI) substrates include a silicon junction above an electrical insulator. SOI substrates have been used to reduce capacitance.
SUMMARY
Implementations of a method of making a silicon-on-insulator (SOI) die may include forming a plurality of grooves in a second side of a silicon substrate, depositing an insulative layer directly to the second side of the silicon substrate, the insulative layer filling the plurality of grooves, the silicon substrate comprising a first side opposite the second side, and singulating the silicon substrate through the plurality of grooves into a plurality of SOI die. The insulative layer may be coupled to silicon only through the second side of the silicon substrate.
Implementations of a method of making an SOI die may include one, all, or any of the following:
The method may include forming one or more semiconductor devices on the first side of the silicon substrate.
The insulative layer may include a thermally conductive material.
The silicon substrate may not include any bubbles therein.
The silicon substrate may not include implanted gas therein.
The method may include forming a ring through backgrinding the second side of the silicon substrate.
The method may include removing the ring prior to singulating the silicon substrate.
Implementations of a method of making a silicon-on-insulator (SOI) die may include forming a plurality of grooves into a second side of a silicon substrate and depositing an insulative layer directly to the second side of a silicon substrate and into the plurality of grooves. The silicon substrate may include a first side opposite the second side. The method may include backgrinding the silicon substrate to a thickness less than 35 micrometers thick and singulating the silicon substrate through the plurality of grooves into a plurality of SOI die. The insulative layer may be coupled to silicon only through the second side of the silicon substrate.
Implementations of a method of making an SOI die may include one, all, or any of the following:
- The method may include forming one or more semiconductor devices on the first side of the silicon substrate.
- The insulative layer may include a thermally conductive material.
- The silicon substrate may not include any bubbles therein.
- The method may not include implanting hydrogen.
- The method may include forming a ring through backgrinding the second side of the silicon substrate.
Implementations of a method of making a silicon-on-insulator (SOI) die may include forming a plurality of grooves into a second side of a silicon substrate, depositing a conductive layer onto the second side of the silicon substrate, the silicon substrate comprising a first side opposite the second side, depositing an insulative layer over the conductive layer and into the plurality of grooves, and singulating the silicon substrate into a plurality of SOI die.
Implementations of a method of making an SOI die may include one, all, or any of the following:
- The method may include backgrinding the silicon substrate to a thickness less than 35 micrometers thick.
- The method may include patterning the conductive layer.
- The silicon substrate may not include any bubbles therein.
- The insulative layer may not be coupled to any other silicon substrate.
- The conductive layer may include titanium.
- The method may include forming one or more semiconductor devices on the first side of the silicon substrate.
The foregoing and other aspects, features, and advantages will be apparent to those artisans of ordinary skill in the art from the DESCRIPTION and DRAWINGS, and from the CLAIMS.
BRIEF DESCRIPTION OF THE DRAWINGS
Implementations will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and:
FIG. 1 is a cross sectional side view of a silicon-on-insulator (SOI) die;
FIG. 2 is a cross sectional side view of an SOI substrate with a ring formed around the perimeter thereof;
FIGS. 3A-3J are cross sectional side views of an implementation of a method of forming an SOI die;
FIGS. 4A-4E are cross sectional side views of a second implementation of a method of forming an SOI die;
FIG. 5 is a cross sectional side view of an SOI die;
FIG. 6 is a cross sectional side view of an SOI substrate with a ring formed around the perimeter thereof;
FIG. 7 is a cross sectional side view of an SOI substrate without a ring formed around the perimeter thereof;
FIGS. 8A-8J are cross sectional side views of a third implementation of a method of forming an SOI die; and
FIGS. 9A-9C are cross sectional side views of a portion of a fourth implementation of a method of forming an SOI die.
DESCRIPTION
This disclosure, its aspects and implementations, are not limited to the specific components, assembly procedures or method elements disclosed herein. Many additional components, assembly procedures and/or method elements known in the art consistent with the intended silicon-on-insulator (SOI) substrates and die will become apparent for use with particular implementations from this disclosure. Accordingly, for example, although particular implementations are disclosed, such implementations and implementing components may comprise any shape, size, style, type, model, version, measurement, concentration, material, quantity, method element, step, and/or the like as is known in the art for such SOI substrates and die, and implementing components and methods, consistent with the intended operation and methods.
Referring to FIG. 1, a cross sectional side view of an SOI die is illustrated. The SOI die 2 includes a silicon layer 4. The silicon layer 4 includes a first side 6 and a second side 8 opposite the first side. In various implementations, the silicon layer 4 may be, by non-limiting example, an epitaxial silicon layer, a polysilicon layer, a single crystal silicon layer, any combination thereof, or any other silicon-containing layer material. In other implementations, it is understood that a layer other than a silicon-containing layer may be used, such as, by non-limiting example, gallium arsenide, silicon carbide, or a metal-containing layer. While this disclosure primarily refers to silicon and SOI die, it is understood that the principles disclosed herein may be applied to other non-silicon containing die. In various implementations, one or more semiconductor devices may be coupled to the first side 6 of the silicon layer. In such implementations, the one or more semiconductor devices may include high voltage junction devices or power management devices, while in other implementations the one or more semiconductor devices may include other types of semiconductor devices.
In various implementations, the silicon layer 4 may be less than 35 micrometers (microns, um) thick. In other implementations, it may be 35 or more um thick. In particular implementations, the silicon layer 4 may be as thin as about 8 um thick. In implementations where the silicon layer 4 is to be used in medium voltage applications [100 volts (V) or 2 amps (A)], the silicon layer may be about 20-30 um thick. In other implementations where the silicon layer 4 is to be used in high voltage applications (1 kV, 10 A), the silicon layer may be greater than 100 um thick.
The SOI die also includes an insulative layer 10 coupled to the second side 8 of the layer 4. In various implementations, the insulative layer 10 may be coupled directly to the second side 8 of the layer 4. The insulative layer may include any electrical insulator, and in particular implementations, may include an electrical insulator which is thermally conductive. In particular implementations, the insulative layer may include, by non-limiting example, BN, AlN, AlOx, TiOx, TiNx, SiO2, sapphire (alpha-Al2O3), Mica, Ta2O5, diamond, SixNy, SiC, GaN, graphene oxide, nanocomposite silicates, silicon rubber, a graphite polymer matrix, tungsten carbide, any other electrically insulative material, or any combination thereof. In implementations where the SOI die 2 is to be used in medium voltage applications [100 volts (V) or 2 amps], the insulative layer may be about 2,000-5,000 Angstroms (A) thick. In other implementations where the SOI die 2 is to be used in high voltage applications (1 kV, 10 amps), the insulative layer may be about 1 um thick. In other implementations, the insulative layer may be less than 2 kA thick or more than 1 um thick. In particular implementations, the thickness of the insulative layer may be 3 um or more thick.
In various implementations, and as illustrated by FIG. 1, the sidewalls of the insulative layer 10 may be a continuous layer coextensive with the sidewalls 12 of the silicon layer 4. In other implementations, the insulative layer 10 may be patterned. Though not illustrated by FIG. 1, in various implementations the SOI die 2 may include a conductive layer directly coupled to the second side 8 of the layer 4. In particular implementations, the conductive layer may be between the layer 4 and the insulative layer 10. In implementations where the insulative layer 10 is patterned, the conductive layer may fill the recesses in the insulative layer. The conductive layer may also be patterned. In implementations including a conductive layer, the conductive layer may include titanium, aluminum, copper, gold, silver nickel, any other metal, any alloy thereof, or any combination thereof.
In various implementations, the insulative layer 10 is not coupled to any other layer or silicon layer aside from the silicon layer 4. While various implementations of SOI die include a layer of silicon over an insulative layer over a second layer of silicon (or at least a portion of a second layer of silicon), the implementations of the SOI die disclosed herein may only include a single silicon layer. In such implementations, this may allow for the second side 14 of the insulative layer 10 to be fully exposed. In particular implementations, the SOI die may only include a silicon layer 4 having a first side 6 and a second side 8 and an insulative layer 10 directly coupled to the second side 8 of the silicon layer 4. The insulative layer 10 may be patterned in various implementations. In other implementations, the SOI die may only include a silicon layer having a first side and a second side, a semiconductor device coupled to or formed on/in the first side of the silicon layer, and an insulative layer coupled directly to the second side of the silicon layer. In still other implementations, the SOI die may only include a silicon layer having a first side and a second side, an insulative layer coupled to the second side of the silicon layer, and a conductive layer directly coupled to the second side of the silicon layer as well as the insulative layer.
Referring to FIG. 2, a cross sectional side view of an SOI substrate with a ring formed around the perimeter thereof is illustrated. In various implementations, the substrate 16 illustrated by FIG. 2 may be formed prior to forming the SOI die 2 illustrated by FIG. 1. The SOI substrate 16 includes a substrate 18 having a first side 24 and a second side 26. The substrate 18 may be, by non-limiting example, an epitaxial silicon substrate, a polysilicon substrate, single crystal silicon substrate, any combination thereof, or any other silicon-containing substrate material. In other implementations, it is understood that a substrate other than a silicon-containing substrate may be used, such as, by non-limiting example, gallium arsenide, silicon carbide, or a metal-containing substrate. While this disclosure primarily refers to silicon and SOI substrates, it is understood that the principles disclosed herein may be applied to other non-silicon containing substrates. As illustrated by FIG. 2, the substrate 18 includes a thinned portion 20 and a ring 22 extending around the perimeter of the substrate. The ring may result from backgrinding in a process marketed under the trade name TAIKO by DISCO of Tokyo, Japan. The thinned portion 20 of the substrate 18 may be less than 35 micrometers (um) thick. In other implementations, it may be 35 or more um thick. In particular implementations, the thinned portion 20 of the substrate 18 may be as thin as about 8 um thick. In other particular implementations, the thinned portion 20 of the substrate may be about 20-30 um thick.
The SOI substrate 16 includes an insulative layer 28 coupled to the second side 26 of the substrate 18. In various implementations, the insulative layer 28 may be coupled directly to the second side 26 of the substrate 18. The insulative layer may include any electrical insulator, and in particular implementations, may include an electrical insulator which is thermally conductive. In particular implementations, the insulative layer may include, by non-limiting example, BN, AlN, AlOx, TiOx, TiNx, SiO2, sapphire (alpha-Al2O3), Mica, Ta205, diamond, SixNy, SiC, GaN, graphene oxide, nanocomposite silicates, silicon rubber, a graphite polymer matrix, tungsten carbide, any other electrically insulative material, or any combination thereof. In various implementations, the insulative layer 28 may be about 2,000-5,000 Angstroms (A) thick. In other implementations, the insulative layer 28 may be about 1 um thick. In still other implementations, the insulative layer 28 may be less than 2 kA thick, more than 1 um thick, or between 2 kA and 1 um thick. In particular implementations, the insulative layer may be 3 um or more than 3 um thick. In various implementations, and as illustrated by FIG. 2, the insulative layer 28 may be a solid and continuous layer covering the second side 26 of the substrate 18. In other implementations, the insulative layer 28 may be patterned. In various implementations, the insulative layer 28 is not coupled to any other substrate aside from the substrate 18.
In various implementations, the SOI substrate 16 may also include a conductive layer coupled to the insulative layer 28 and to the second side 26 of the substrate 18 (not illustrated in FIG. 2). In various implementations, the conductive layer may be directly coupled to the second side 26 of the substrate 18. In particular implementations, the conductive layer may be between the substrate 18 and the insulative layer 28. In implementations including a conductive layer, the conductive layer may any type of material previously disclosed herein and may or may not be patterned.
Referring to FIGS. 3A-3J, cross sectional side views of a substrate at various points of a method for forming an SOI die is illustrated. Referring specifically to FIG. 3A, the method for forming an SOI die may include forming a plurality of semiconductor devices 30 on, or coupling a plurality of semiconductor devices 30 to, a first side 34 of a substrate 32. While FIGS. 3A-3J indicate that the plurality of semiconductor devices 30 are formed on the substrate 32 before thinning the substrate and/or before applying an insulative layer, in other implementations, the plurality of semiconductor devices may be formed on the substrate after thinning the substrate and/or after applying an insulative layer to the substrate. The plurality of semiconductor devices may be any type of semiconductor device disclosed herein.
Referring to FIG. 3B, the method for forming an SOI die may include applying backgrind tape 38 to the first side 34 of the substrate 32. Referring to FIG. 3C, the method may also include initially thinning the substrate 42. In various implementations, the substrate may be initially thinned to about 355 um, though in other implementations the substrate may be thinned to more or less than this thickness. The substrate 32 may be thinned through backgrinding, etching, or any other thinning technique.
Referring to FIG. 3D, the method for forming an SOI die includes forming a ring 40 around the perimeter of a second side 36 of a substrate 32 through backgrinding the second side of the substrate 32 to a desired substrate thickness. In particular implementations, the backgrinding may use a process marketed under the trade name TAIKO by DISCO Corporation of Tokyo, Japan. The backgrinding leaves a ring of non-removed material (TAIKO ring) along the perimeter of the second side 36 of the substrate 32 which helps to prevent the substrate from curling, warping or otherwise bending during further processing while at the same time removing most of the thickness and material of the second side 36 of the substrate 32. The ring 40 may also offer sufficient stress management for the insulative layer applied to the substrate as described later herein. In other implementations of methods of forming semiconductor devices the TAIKO process may not be used, but another backgrinding or other material-removal technique may be used, such as removing the material through a wet etch. In various implementations, the thinned portion 42 of the substrate 32 may be 50 um thick. In other implementations, it may be more or less than 50 um thick, including any die or substrate thickness previously disclosed herein.
Referring to FIG. 3E, the method for forming an SOI die may include etching the second side 36 of the substrate 32, or the thinned portion 42. In particular implementations, the etching may be stress relief etching. This stress relief etching may be used to obtain the final desired thickness of the wafer. The stress relief etching may include wet chemical etching. In other implementations, it may include dry etching or polishing instead of wet chemical etching, however, wet chemical etching may result in a cleaner substrate with less residual particles. Acid may be used to etch the substrate, and in various implementations may include, by non-limiting example, hydrofluoric acid, acetic acid, nitric acid, and any other acid or combination thereof. The wet chemical etch may be tightly monitored and controlled so that the targeted thickness of the wafer is achieved. In various implementations, the second side 36 of the substrate 32 may be etched until the thinned portion 42 of the substrate is 25 um thick. In other implementations, the substrate 32 may be etched until thinned portion 42 is more or less than 25 um thick. In implementations where the substrate is wet etched, the wet etch may prepare the substrate to better adhere to later deposited materials and/or devices. In various implementations, the backgrind tape 38 may be removed.
Referring to FIG. 3F, the method for forming an SOI die includes depositing an insulative layer 44 onto the second side 36 of the substrate 32 after backgrinding. In various implementations, the insulative layer 44 may be deposited at a low temperature. The low temperature deposition may allow for the insulative layer to be deposited without overheating the substrate, especially in instances where the substrate has been thinned. The substrate 32 may have a low thermal resistance. In various implementations, the insulative layer may be deposited through spin-on techniques, chemical vapor deposition (CVD), sputtering, evaporation, co-sputtering, or co-evaporation, and in particular implementations, may be deposited at a temperature that does not require heat dissipation. In implementations where the insulative layer is deposited using either co-sputtering or co-evaporation, the overall performance of the SOI die and the adhesion of the insulative layer 44 to the substrate 32 may be improved. In various implementations, however, the method may include dissipating heat through a heat dissipation device during deposition of the insulative layer 44. The heat dissipation device may include, among other devices, cooling chucks or common evaporators. The insulative layer 44 may be any insulative material previously disclosed herein, and may be applied in any thickness previously disclosed herein. In the implementation illustrated by FIG. 3F, the method includes depositing the insulative layer 44 directly to the second side 36 of the substrate 32. In other implementations, the method may include directly depositing a conductive layer to the second side of the substrate prior to deposition of the insulative layer. The conductive layer may enhance the adhesion between the insulative layer and the substrate as well as provide potential electrical contacts on the substrate. In such implementations, the conductive layer may include any electrically conductive material disclosed herein. In various implementations, the conductive layer may be deposited through, by non-limiting example, sputtering, evaporation, electroplating, any other deposition technique, or any combination thereof.
Referring to FIG. 3G, the method for forming an SOI die includes mounting the substrate 32 to a film frame. The first side 34 and/or the plurality of semiconductor devices 30 may be directly coupled to the film frame 46. Referring to FIG. 3H, the method may include removing the ring 40. The ring may be removed through grinding the ring portion of the substrate. In other implementations, the ring may be removed through plasma etching or cutting the ring from the remaining substrate using, by non-limiting example, a laser or a saw. In various implementations, the ring is removed to the extent that the backside 48 of the SOI substrate 50 opposite the side of the SOI substrate coupled to the film frame is substantially level.
Referring to FIG. 3I, the method for forming an SOI die includes applying a final dicing tape 52 to the backside 48 of the SOI substrate 50, or to the insulative layer 44. In such implementations, the method may also include removing the exposed tape used to couple the substrate 32 to the film frame explained in FIG. 3G. In other implementations, rather than applying the final dicing tape, the SOI substrate may be flipped so the insulative layer 44 is directly coupled to the existing tape.
Referring to FIG. 3J, the method for forming an SOI die may include singulating the substrate 32 (and the SOI substrate 50) into a plurality of SOI die 54. The SOI substrate may be singulated through, by non-limiting example, a saw 56, a laser, plasma etching, or any other singulation device or method. In various implementations, the SOI die may be coupled to an interposer after singulation.
Referring to FIGS. 4A-4E, cross sectional side views of a second implementation of a method for forming an SOI die are illustrated. Referring specifically to FIG. 4A, the method may include patterning an insulative layer 58 coupled to a second side 60 of a substrate 62. As illustrated, the substrate 62 has been thinned to form a ring using any of the thinning methods disclosed in this document. In such implementations, the method includes masking the insulative layer and removing portions of the insulative layer where the mask pattern is absent. The SOI substrate 64 may be the same as or similar to the SOI substrate illustrated in FIG. 3F with the exception that the insulative layer 58 is patterned. The process used to produce the SOI substrate illustrated by and described in relation to FIG. 3F may also be used in making the SOI substrate with the patterned insulative layer illustrated in FIG. 4A.
In the implementation illustrated by FIG. 4A, the method includes depositing the insulative layer 58 directly onto the second side 60 of the substrate 62. In other implementations, the method may include directly depositing a conductive layer onto the second side of the substrate prior to deposition of the insulative layer. The conductive layer may enhance the adhesion between the insulative layer and the substrate as well as provide potential electrical contacts on the substrate. The conductive layer may be patterned. In still other implementations, the conductive layer may be deposited within recesses 64 formed in the patterned insulative layer 58. The conductive layer may also cover all of or a portion of a second side 66 of the insulative layer 58 opposite the first side 68 of the insulative layer. The conductive layer may include any conductive material disclosed herein. In various implementations, the conductive layer may be deposited through, by non-limiting example, sputtering, evaporation, electroplating, any other deposition technique, or any combination thereof.
Referring to FIG. 4B, implementations of a method for forming an SOI die includes mounting the substrate 62 to a film frame 70. The first side 72 and/or the plurality of semiconductor devices 74 may be directly coupled to the film frame 70. Referring to FIG. 4C, the method may include removing the ring 76. The ring 76 may be removed through grinding the ring portion of the substrate or any other method disclosed in this document. In various implementations, the ring is removed to the extent that the second side 78 of the substrate 62 on the ends 80 of the substrate are substantially level with the second side 66 of the insulative layer 58.
Referring to FIG. 4D, the method for forming an SOI die may include applying a final dicing tape 82 to the second side 66 of the insulative layer 58. In such implementations, the method may also include removing the exposed tape used to couple the substrate 62 to the film frame 70 as explained in relation to FIG. 4B. In other implementations, rather than applying the final dicing tape, the SOI substrate 84 may be flipped so the insulative layer 58 is directly coupled to the existing tape.
Referring to FIG. 4E, the method for forming an SOI die includes singulating the substrate 62 (and the SOI substrate 84) into a plurality of SOI die 86. The SOI substrate 84 may be singulated through, by non-limiting example, a saw 88, a laser, plasma etching, or any other singulation device or method. In various implementations, the SOI die may be coupled to an interposer after singulation.
Referring to FIG. 5, a cross section side view of an SOI die is illustrated. Like the SOI die 2 of FIG. 1, the SOI die 90 may include a silicon layer 92. The silicon layer 92 includes a first side 94 and a second side 98 opposite the first side. In various implementations, the silicon layer 92 may include any type of silicon containing material disclosed herein. In other implementations, the silicon layer may be replaced by a non-silicon layer, including any non-silicon layer disclosed herein.
The silicon layer 92 may include any thickness of a silicon layer disclosed herein. In various implementations, the silicon layer 92 may include a step 96 formed in the outer perimeter of the silicon layer. The step 96 may be formed in all the outer sidewalls of the silicon layer 92 or only some of the outer sidewalls (such as one, two, or three outer sidewalls). In such implementations, the silicon layer 92 includes a first portion 100 having a width less than a width of a second portion 102 that extends between the outermost sidewalls of the SOI die 90. In various implementations, the thickness of the first portion 100, or the depth of the step 96, may be substantially 30%, 50%, 70%, or any other percent of the thickness of the silicon layer.
The SOI die also includes an insulative layer 104 coupled to the second side 98 of the silicon layer 92. In various implementations, the insulative layer 104 may be coupled directly to the second side 98 of the silicon layer 92. The insulative layer 104 may include any oxide or other insulative material disclosed herein. The insulative layer 104 may also include any thickness of insulative layer disclosed herein.
In implementations where the silicon layer 92 includes a step 96, the insulative layer 104 may fill the step. In such implementations, the insulative layer 104 covers a portion of one or more of the sidewalls of the silicon layer 92. In such implementations, the insulative layer 104 covering a portion of the one or more sidewalls may prevent shorts or leakage within the die or any devices formed thereon resulting from solder climbing the sidewall of the die and making an electrical connection with the die or any device formed thereon. The reduction or prevention of shorts and leakage may result from the insulative layer further insulating the die or devices formed thereon from solder used to couple the die to an external surface.
In various implementations, and as illustrated by FIG. 5, the sidewalls of the insulative layer 104 may be a continuous layer coextensive with the sidewalls of the second portion 102 of the silicon layer 92. In various implementations, though not illustrated, the insulative layer 104 may be patterned. Though not illustrated by FIG. 5, in various implementations the SOI die 90 may include a conductive layer directly coupled to the silicon layer. The conductive layer may be the same as the conductive layer directly coupled to the silicon layer of FIG. 1.
In various implementations, the insulative layer 104 is not coupled to any other layer or silicon layer aside from the silicon layer 92. In particular implementations, the SOI die may only include a silicon layer 92 having a first side 94 and a second side 98 and an insulative layer 104 directly coupled to the second side 98 of the silicon layer 92. The insulative layer 104 may be patterned in various implementations. In other implementations, the SOI die 90 may only include a silicon layer having a first side and a second side, a semiconductor device coupled to or formed on/in the first side of the silicon layer, and an insulative layer coupled directly to the second side of the silicon layer. In still other implementations, the SOI die 90 may only include a silicon layer having a first side and a second side, an insulative layer coupled to the second side of the silicon layer, and a conductive layer directly coupled to the second side of the silicon layer as well as the insulative layer.
Referring to FIG. 6, a cross sectional side view of an SOI substrate with a ring formed around the perimeter thereof is illustrated. In various implementations, the substrate 106 illustrated by FIG. 6 may be formed prior to forming the SOI die 90 illustrated by FIG. 1. The SOI substrate 16 includes a substrate 108, or wafer, having a first side 110 and a second side 112. The substrate 108 may include any type of substrate material disclosed herein. As illustrated by FIG. 6, the substrate 108 includes a thinned portion 114 and a ring 116 extending around the perimeter of the substrate. The ring may be the same as and formed through the same methods as disclosed in relation to the ring of FIG. 2 disclosed herein. The thinned portion 114 of the substrate may include any thickness disclosed herein.
In various implementations, the substrate 108 includes a plurality of grooves 118 formed in the second side 112 of the substrate. The plurality of grooves may extend substantially 30%, 50%, 70%, or any other percent of the thickness of the substrate 108 into the thickness of the substrate 108. In various implementations, the grooves 118 may intersect one another. In particular implementations, the plurality of grooves may be formed along the singulation lines of the wafer. In such implementations, the resulting singulated die may include a stepped portion of the substrate resulting from the grooves 118 formed in the substrate 108.
In implementations of the substrate 108 including the ring 116, the plurality of grooves may be formed in the thinned portion 114 of the substrate 108 and do not extend into the ring 116.
The SOI substrate 106 includes an insulative layer 120 coupled to the second side 112 of the substrate 108 and filling the plurality of grooves 118. In various implementations, the insulative layer 120 may be coupled directly to the second side 112 of the substrate 108. The insulative layer may include any material disclosed herein and may include any thickness disclosed herein. In various implementations, and as illustrated by FIG. 6, the insulative layer 120 may be a solid and continuous layer covering the second side 112 of the substrate 108. In other implementations, the insulative layer 120 may be patterned. In various implementations, the insulative layer 120 is not coupled to any other silicon substrate aside from the substrate 108.
In various implementations, though not illustrated by FIG. 6, the SOI substrate 106 may also include a conductive layer coupled to the insulative layer 120 and to the second side 112 of the substrate 108. In various implementations, the conductive layer may be directly coupled to the second side 112 of the substrate 108. In particular implementations, the conductive layer may be between the substrate 108 and the insulative layer 120. In implementations including a conductive layer, the conductive layer may include any type of material previously disclosed herein and may or may not be patterned.
Referring to FIG. 7, a cross sectional side view of an SOI substrate without a ring formed around the perimeter thereof is illustrated. In various implementations, the substrate 122 includes a substrate 124 that does not include a ring formed around the perimeter thereof. The substrate 122 may be the same as the substrate except for the difference of the substrate 124 not including the ring. In turn, the insulative layer 126 may extend to an outer edge of the substrate 122 and the plurality of grooves 128 may also extend to an outer edge of the substrate 122. The substrate 124 may be thinned or may not be thinned.
Referring to FIGS. 8A-8J, cross sectional side views of a substrate at various points of a method for forming an SOI die is illustrated. Referring specifically to FIGS. 8A-8D, the method of forming the SOI die may be the same as the method illustrated by FIGS. 3A-3D.
In various implementations, the method for forming an SOI die may include etching the second side 130 of the substrate 132, or the thinned portion 134. In particular implementations, the etching may be stress relief etching. This stress relief etching may be used to obtain the final desired thickness of the wafer. The stress relief etching may include any type of etching disclosed herein. In other implementations, it may include polishing instead of etching, however, wet chemical etching may result in a cleaner substrate with less residual particles. Acid may be used to etch the substrate, and in various implementations may include any acid disclosed herein. The wet chemical etch may be tightly monitored and controlled so that the targeted thickness of the wafer is achieved. In various implementations, the second side 130 of the substrate 132 may be etched to any thickness disclosed herein. In implementations where the substrate is wet etched, the wet etch may prepare the substrate to better adhere to later deposited materials and/or devices. In various implementations, the backgrind tape 136 may be removed.
Referring to FIG. 8E, the method for forming an SOI die may include forming a plurality of grooves 138 into the second side 130 of the substrate 132. In various implementations, the plurality of grooves may be formed in the substrate 132 to any depth disclosed herein. In implementations including the edge support ring 140, the plurality of grooves 138 may be formed in the thinned portion 134 of the substrate 132 and may not extend into the ring 140 (and in turn, may not extend to an outer edge of the substrate). The plurality of grooves 138 may be formed into the substrate 132 along the lines where the substrate will be singulated.
In various implementations, the plurality of grooves 138 may be formed with, by non-limiting example, a saw, a laser, a water jet, an etchant, or any other device capable of cutting or forming grooves into a substrate. In implementations including the edge support ring 140 in the substrate, where a saw is used to cut the grooves into the substrate, the method may include lowering the saw blade from over the thinned portion 134 of the substrate 132 into the thinned portion of the substrate, cutting the groove across the thinned portion of the substrate, and then raising the saw blade from the thinned portion of the substrate to prevent the saw blade from cutting into the edge support ring.
Referring to FIG. 8F, the method for forming an SOI die includes depositing an insulative layer 142 onto the second side 130 of the substrate 132 and into the plurality of grooves 138 after backgrinding. The insulative layer 142 may be the same as any insulative layer disclosed herein and may be deposited using any method disclosed herein.
In the implementation illustrated by FIG. 8F, the method includes depositing the insulative layer 142 directly to the second side 130 of the substrate 132. In other implementations, the method may include directly depositing a conductive layer to the second side of the substrate prior to deposition of the insulative layer. The conductive layer may enhance the adhesion between the insulative layer and the substrate as well as provide potential electrical contacts on the substrate. In such implementations, the conductive layer may include any electrically conductive material disclosed herein. In various implementations, the conductive layer may be deposited through, by non-limiting example, sputtering, evaporation, electroplating, any other deposition technique, or any combination thereof.
Referring to FIG. 8G, the method for forming an SOI die includes mounting the substrate 132 to a film frame 144. Referring to FIG. 8H, the method may include removing the ring 140. Referring to FIG. 8I, the method may include applying a final dicing tape 146 to the insulative layer 142. The methods illustrated by FIGS. 8G-8I may include the same elements of the methods disclosed herein relating to FIGS. 3G-3I.
Referring to FIG. 8J, the method for forming an SOI die may include singulating the substrate 132 into a plurality of SOI die 148. In various implementations, singulation occurs through the plurality of grooves. In such implementations, the resulting SOI die may include an insulative material extending along a portion of the sidewall of the die as illustrated by the die of FIG. 5. A portion of the insulative layer 142 that fills the plurality of grooves may remain on the sidewalls of the plurality of SOI die inasmuch as the width of the saw blade (or width of saw street) may be thinner than a width of the each groove of the plurality of grooves. The SOI substrate may be singulated through, by non-limiting example, a saw 150, a laser, plasma etching, or any other singulation device or method. In various implementations, the SOI die may be coupled to an interposer after singulation.
Referring to FIGS. 9A-9C, cross sectional side views of a portion of a fourth implementation of a method of forming an SOI die are illustrated. The method may include providing a substrate 152 which may be the same as substrate 132 illustrated by FIG. 8B. The substrate 152 may be obtained using the same method described in relation to FIGS. 8A-8C. In various implementations, the method may include thinning the substrate 152. In other implementations, thinning may not be part of the method of forming the SOI die.
The method illustrated by FIGS. 9A-9C does not include forming an edge support ring through backgrinding the substrate.
In various implementations, and as illustrated by FIG. 9B, the method of forming the SOI die may include forming a plurality of grooves 154 into the second side 156 of the substrate 152. The plurality of grooves 154 may be formed in the substrate 152 to any depth disclosed herein. The plurality of grooves 154 may be formed into the substrate 152 along the lines where the substrate will be singulated.
In various implementations, the plurality of grooves 154 may be formed using any device capable of cutting or forming grooves into a substrate, including any device disclosed herein. The plurality of grooves 154 may extend to the outer edges of the substrate inasmuch as the groove does not need to terminate prior to reaching an edge support ring. In implementations where a saw is used to form the plurality of grooves 154, the saw may cut all the way across the substrate 152 without the saw or the substrate having to change its respective level to prevent a ring from being cut.
Referring to FIG. 9C, the method for forming an SOI die includes depositing an insulative layer 158 onto the second side 156 of the substrate 152 and into the plurality of grooves 154 after backgrinding. The insulative layer 158 may be the same as any insulative layer disclosed herein and may be deposited using any method disclosed herein.
In other implementations, the method may include directly depositing a conductive layer to the second side 156 of the substrate 152 prior to deposition of the insulative layer 158. The conductive layer may enhance the adhesion between the insulative layer and the substrate as well as provide potential electrical contacts on the substrate. In such implementations, the conductive layer may include any electrically conductive material disclosed herein. In various implementations, the conductive layer may be deposited through, by non-limiting example, sputtering, evaporation, electroplating, any other deposition technique, or any combination thereof.
The method of forming a plurality of SOI die from the substrate 152 may be the same as the method of singulating the substrate 132 into a plurality of SOI die as illustrated by and described herein in relation to FIGS. 8I-8J.
While the methods illustrated by FIGS. 8A-8J and 9A-9C illustrate a non-patterned insulative layer, in other implementations the method may include patterning the insulative layers using any method of patterning an insulative layer disclosed herein.
The implementations of SOI substrates and SOI die disclosed herein may be formed without using a process that implants hydrogen within a substrate, without forming bubbles within the substrate, without breaking the substrate, and/or without having to polish the substrate. Further, the method may be performed without using a sacrificial carrier substrate and without having to cut, grind, or otherwise remove the sacrificial carrier substrate. The methods of forming such implementations of SOI die may have sufficient stress management of the backside insulating material to be able to form an SOI die without a sacrificial carrier substrate while still having a thin silicon layer coupled to the insulative layer. In this way, no remaining carrier material may be present in the resulting SOI die.
In places where the description above refers to particular implementations of SOI substrates/die implementing components, sub-components, methods and sub-methods, it should be readily apparent that a number of modifications may be made without departing from the spirit thereof and that these implementations, implementing components, sub-components, methods and sub-methods may be applied to other SOI substrates/die.
Patent Application
20250167102
