Abstract: A method for manufacturing a fin transistor includes forming a trench by etching a semiconductor substrate. A flowable insulation layer is filled in the trench to form a field insulation layer defining an active region. The portion of the flowable insulation layer coming into contact with a gate forming region is etched so as to protrude the gate forming region in the active region. A protective layer over the semiconductor substrate is formed to fill the portion of the etched flowable insulation layer. The portion of the protective layer formed over the active region is removed to expose the active region of the semiconductor substrate. The exposed active region of the semiconductor substrate is cleaned. The protective layer remaining on the portion of the etched flowable insulation layer is removed. Gates are formed over the protruded gate forming regions in the active region.

Abstract: A method of forming a MOSFET is provided. The method comprises forming a relatively thin layer of dielectric on a substrate. Depositing a gate material layer on the relatively thin layer of dielectric. Removing portions of the gate material layer to form a first and second gate material regions of predetermined lateral lengths. Introducing a first conductivity type dopant in the substrate to form a top gate using first edges of the first and second gate material regions as masks, Introducing a second conductivity dopant of high dopant density in the substrate to form a drain region adjacent the surface of the substrate using a second edge of the second gate material region as a mask to form a first edge of the drain region, wherein a spaced distance between the top gate and the drain region is determined by the lateral length of the second gate material region.

Abstract: A field effect transistor includes an active region provided in a projecting part on a surface of a semiconductor substrate, the projecting part extending in a fixed direction parallel to the surface, and a gate electrode provided on a sidewall of the projecting part along the fixed direction with a gate insulating films interposed.

Abstract: A process is described to enable the manufacture of a thinned (<50 ?m semiconductor die) which can employ the use of standard equipment for the manufacture of the wafer and the packaging of the die singulated from the wafer. A standard thickness wafer (350 ?m) first has junctions formed in its upper surface, but the surface is not yet metallized and patterned. A rigid front plate is connected to the upper surface by a removable adhesive and the wafer is back ground to its final thickness, for example, less than 50 ?m. A back metal and a thick conductive backing plate are then fixed to the back metal. The rigid front plate is then removed and the front surface of the wafer is metallized and patterned. Die singulated from the wafer carry the thick permanent conductive backing plate and may be conventionally packaged as prior art 350 ?m die. The wafer can initially be partially diced.

Abstract: A fin transistor includes fin active region, an isolation layer covering both sidewalls of a lower portion of the fin active region, a gate insulation layer disposed over a surface of the fin active region, and a gate electrode disposed over the gate insulation layer and the isolation layer, and having a work function ranging from approximately 4.4 eV to approximately 4.8 eV.

Abstract: A method of fabricating a double gate FET on a silicon substrate includes the steps of sequentially epitaxially growing a lower gate layer of crystalline rare earth silicide material on the substrate, a lower gate insulating layer of crystalline rare earth insulating material, an active layer of crystalline semiconductor material, an upper gate insulating layer of crystalline rare earth insulating material, and an upper gate layer of crystalline rare earth conductive material. The upper gate layer and the upper gate electrically insulating layer are etched and a contact is deposited on the upper gate layer to define an upper gate structure. An impurity is implanted into the lower gate layer to define a lower gate area aligned with the upper gate structure. A source and drain are formed in the active layer and contacts are deposited on the source and drain, respectively.

Abstract: A semiconductor device includes a substrate; a nitride based compound semiconductor layer placed on the substrate; an active area which is placed on the nitride based compound semiconductor layer, and is composed of an aluminum gallium nitride layer (AlxGa1-xN) (where 0.1<=x<=1); an isolation region which performs isolation of the active area mutually; a gate electrode, a source electrode, and a drain electrode which have been placed on the active area surrounded by the isolation region; and a trench region formed by etching for a part of the active area under the gate electrode. The semiconductor device is highly reliable, high performance and high power and a fabrication method for the same is also provided.

Abstract: Multiple gate transistors are provided with a dual stress layer for increased channel mobility and enhanced effective and saturated drive currents. Embodiments include transistors comprising a first stress layer under the bottom gate and a second stress layer overlying the top gate. Embodiments further include transistors with the bottom gate within or through the first stress layer. Methodology includes sequentially depositing stressed silicon nitride, nitride, oxide, amorphous silicon, and oxide layers on a substrate having a bottom oxide layer thereon, patterning to define a channel length, depositing a top nitride layer, patterning stopping on the stressed silicon nitride layer, removing the amorphous silicon layer, epitaxially growing silicon through a window in the substrate to form source, drain, and channel regions, doping, removing the deposited nitride and oxide layers, growing gate oxides, depositing polysilicon to form gates, growing isolation oxides, and depositing the top stress layer.

Abstract: An junction field effect transistor (JFET) is fashioned with a patterned layer of silicide block (SBLK) material utilized in forming gate, source and drain regions. Utilizing the silicide block in this manner helps to reduce low-frequency (flicker) noise associated with the JFET by suppressing the impact of surface states, among other things.

Abstract: Unit cells of metal oxide semiconductor (MOS) transistors are provided including an integrated circuit substrate an a MOS transistor on the integrated circuit substrate. The MOS transistor includes a source region, a drain region and a gate. The gate is positioned between the source region and the drain region. A horizontal channel is provided between the source and drain regions. The horizontal channel includes at least two spaced apart horizontal channel regions. Related methods of fabricating MOS transistors are also provided.

Abstract: A transistor is fabricated upon a semiconductor substrate, where the yield strength or elasticity of the substrate is enhanced or otherwise adapted. A strain inducing layer is formed over the transistor to apply a strain thereto to alter transistor operating characteristics, and more particularly to enhance the mobility of carriers within the transistor. Enhancing carrier mobility allows transistor dimensions to be reduced while also allowing the transistor to operate as desired. However, high strain and temperature associated with fabricating the transistor result in deleterious plastic deformation. The yield strength of the silicon substrate is therefore adapted by incorporating nitrogen into the substrate, and more particularly into source/drain extension regions and/or source/drain regions of the transistor. The nitrogen can be readily incorporated during transistor fabrication by adding it as part of source/drain extension region formation and/or source/drain region formation.

Abstract: A lateral double-gate FET structure with sub-lithographic source and drain regions is disclosed. The sub-lithographic source and drain regions are defined by a sacrificial spacer. Self-aligned metal-semiconductor alloy and metal contacts are made to the sub-lithographic source and drain using conventional silicon processing.

Abstract: A semiconductor structure and its method of fabrication include multiple finFETs with different vertical dimensions for the semiconductor fins. An implant species is implanted in a bottom portion of selected semiconductor fins on which reduced vertical dimension is desired. The bottom portion of the selected semiconductor fins with implant species is etched selective to the semiconductor material without the implanted species, i.e., the semiconductor material in the top portion of the semiconductor fin and other semiconductor fins without the implanted species. FinFETs with the full vertical dimension fins and a high on-current and finFETs with reduced vertical dimension fins with a low on-current thus results on the same semiconductor substrate. By adjusting the depth of the implant species, the vertical dimension of the semiconductor fins may be adjusted in selected finFETs.

Abstract: A microelectronic device includes a P-I-N (p+ region, intrinsic semiconductor, and n+ region) semiconductive body with a first gate and a second gate. The first gate is a gate stack disposed on an upper surface plane, and the second gate accesses the semiconductive body from a second plane that is out of the first plane.

Abstract: A semiconductor device suitable for use as a storage cell includes a semiconductor body having a top surface and a bottom surface, a top gate dielectric overlying the semiconductor body top surface, an electrically conductive top gate electrode overlying the top gate dielectric, a bottom gate dielectric underlying the semiconductor body bottom surface, an electrically conductive bottom gate electrode underlying the bottom gate dielectric, and a charge trapping layer. The charge trapping layer includes a plurality of shallow charge traps, adjacent the top or bottom surface of the semiconductor body. The charge trapping layer may be of aluminum oxide, silicon nitride, or silicon nanoclusters. The charge trapping layer may located positioned between the bottom gate dielectric and the bottom surface of the semiconductor body.

Abstract: Embodiments of the invention generally provide a method for depositing films or layers using a UV source during a photoexcitation process. The films are deposited on a substrate and usually contain a material, such as silicon (e.g., epitaxy, crystalline, microcrystalline, polysilicon, or amorphous), silicon oxide, silicon nitride, silicon oxynitride, or other silicon-containing materials. The photoexcitation process may expose the substrate and/or gases to an energy beam or flux prior to, during, or subsequent a deposition process. Therefore, the photoexcitation process may be used to pre-treat or post-treat the substrate or material, to deposit the silicon-containing material, and to enhance chamber cleaning processes.

Abstract: A double-gate field effect transistor (DGFET) structure and method of forming such a structure in which the parasitic capacitance under the source/drain regions is substantially reduced are provided. In the present invention, self-aligned isolation regions are provided to reduce the parasitic capacitance in the DGFET structure. Additionally, the present invention encapsulates the silicon-containing channel layer to enable the back-gate to be oxidized to a greater extent thereby reducing the parasitic capacitance of the structure even further.

Abstract: A method for forming a transistor. A semiconductor substrate is provided. The semiconductor substrate is patterned to provide a first body edge. A first gate structure of a first fermi level is provided adjacent the first body edge. The semiconductor substrate is patterned to provide a second body edge. The first and second body edges of the semiconductor substrate define a transistor body. A second gate structure of a second fermi level is provided adjacent the second body edge. A substantially uniform dopant concentration density is formed throughout the transistor body.

Abstract: Semiconductor memory devices having recessed access devices are disclosed. In some embodiments, a method of forming the recessed access device includes forming a device recess in a substrate material that extends to a first depth in the substrate that includes a gate oxide layer in the recess. The device recess may be extended to a second depth that is greater that the first depth to form an extended portion of the device recess. A field oxide layer may be provided within an interior of the device recess that extends inwardly into the interior of the device recess and into the substrate. Active regions may be formed in the substrate that abut the field oxide layer, and a gate material may be deposited into the device recess.

Abstract: A method of manufacturing a MOS transistor device is provided. First, a semiconductor substrate having a gate structure is prepared. The gate structure has two sidewalls and a liner on the sidewalls. Subsequently, a stressed cap layer is formed on the semiconductor substrate, and covers the gate structure and the liner. Next, an activating process is performed. Furthermore, the stressed cap layer is etched to be a salicide block. Afterward, a salicide process is performed to form a silicide layer on the regions that are not covered by the stressed cap layer.

Abstract: In one embodiment of the invention, a non-planar transistor includes a gate electrode and multiple fins. A trench contact is coupled to the fins. The contact bottom is formed above the substrate and does not directly contact the substrate. The contact bottom is higher than the gate top.

Abstract: Methods of making vertical profile FinFET gate electrodes via plating upon a thin gate dielectric are disclosed. In one embodiment, a method for forming a transistor, comprises: providing a semiconductor topography comprising a semiconductor substrate and a semiconductor fin structure extending above the substrate; forming a gate dielectric across exposed surfaces of the semiconductor topography; patterning a mask upon the semiconductor topography such that only a select portion of the gate dielectric is exposed that defines where a gate electrode is to be formed; and plating a metallic material upon the select portion of the gate dielectric to form a gate electrode across a portion of the fin structure.

Abstract: Semiconductor devices and methods of making the devices are described. The devices can be implemented in SiC and can include epitaxially grown n-type drift and p-type trenched gate regions, and an n-type epitaxially regrown channel region on top of the trenched p-gate regions. A source region can be epitaxially regrown on top of the channel region or selectively implanted into the channel region. Ohmic contacts to the source, gate and drain regions can then be formed. The devices can include edge termination structures such as guard rings, junction termination extensions (JTE), or other suitable p-n blocking structures. The devices can be fabricated with different threshold voltages, and can be implemented for both depletion and enhanced modes of operation for the same channel doping. The devices can be used as discrete power transistors and in digital, analog, and monolithic microwave integrated circuits.

Abstract: A disclosed semiconductor device includes multiple gate electrodes disposed on a semiconductor substrate; and multiple sidewall spacers disposed on sidewalls of the gate electrodes. The thickness of the sidewall spacers is larger on the sidewalls along longer sides of the gate electrodes than on the sidewalls along shorter sides of the gate electrodes.

Abstract: The electrode of a thin-type capacitor is connected to the rear surface of a p-type semiconductor substrate which is brought to a ground potential, by a conductive DAF (Die Attach Film) or by a conductive adhesive, and the electrodes of the front surface of the p-type semiconductor substrate are respectively connected with and stacked on the terminals of a thin-type inductor by bumps, whereby manufacturing costs can be reduced while the occurrence of noise can be suppressed and packaging area can be made small.

Abstract: A method for manufacturing a semiconductor memory apparatus may include forming a channel region and a gate region through a self-alignment etching process on a cell region; and forming a three-dimensional multi-channel region through an etching process using a first multi-channel mask on a core region and a peripheral region and forming a gate region through an etching process using a second multi-channel mask, thereby preventing mis-arrangement of gates.

Abstract: Integrated circuit field effect transistor devices include a substrate having a surface and an active channel pattern on the surface. The active channel pattern includes channels that are stacked upon one another and are spaced apart from one another to define at least one tunnel between adjacent channels. A gate electrode surrounds the channels and extends through the at least one tunnel. A pair of source/drain regions also is provided. Integrated circuit field effect transistors are manufactured, by forming a pre-active pattern on a surface of a substrate. The pre-active pattern includes a series of interchannel layers and channel layers stacked alternately upon each other. Source/drain regions are formed on the substrate at opposite ends of the pre-active pattern. The interchannel layers are selectively removed to form tunnels. A gate electrode is formed in the tunnels and surrounding the channels.

Abstract: A method of manufacturing a semiconductor device of the present invention consists of forming a trench in a trench-type cell transistor region; forming a gate insulating film and a gate material layer on a semiconductor substrate; forming a photoresist layer on the semiconductor substrate so as to expose extension region formation portions of the trench-type cell transistor region and a high breakdown voltage transistor region; forming extension regions in each region by performing ion implantation in the semiconductor substrate surface of the trench-type cell transistor region and the high breakdown voltage transistor region and then patterning gates, and forming extension regions of an ordinary breakdown voltage transistor by covering the trench-type cell transistor region and the high breakdown voltage transistor region with a photoresist layer and implanting ions in the ordinary breakdown voltage transistor region.

Abstract: A method patterns pairs of semiconducting fins on an insulator layer and then patterns a linear gate conductor structure over and perpendicular to the fins. Next, the method patterns a mask on the insulator layer adjacent the fins such that sidewalls of the mask are parallel to the fins and are spaced from the fins a predetermined distance. The method performs an angled impurity implant into regions of the fins not protected by the gate conductor structure and the mask. This process forms impurity concentrations within the fins that are asymmetric and that mirror one another in adjacent pairs of fins.

Abstract: In one embodiment of the present invention an array of power transistors on a semiconductor chip has repeating patterns of two “wave” gates which have alternating longer and shorter horizontal sections which are offset mirror images of each other together with a third straight horizontal section. Alternating source and drain regions lie between adjacent gates. Contacts are located adjacent each side of sections of the “wave” gates which connect the ends of the horizontal sections of the “wave” gates.

Abstract: A multi-gate field effect transistor includes: a plurality of semiconductor layers arranged in parallel on a substrate; source and drain regions formed in each of the semiconductor layers; channel regions each provided between the source region and the drain region in each of the semiconductor layers; protection films each provided on an upper face of each of the channel regions; gate insulating films each provided on both side faces of each of the channel regions; a plurality of gate electrodes provided on both side faces of each of the channel regions so as to interpose the gate insulating film, provided above the upper face of each of the channel region so as to interpose the protection film, and containing a metal element; a connecting portion connecting upper faces of the gate electrodes; and a gate wire connected to the connecting portion.

Abstract: Disclosed are methods, systems and devices, including devices having a plurality of data cells. In some embodiments, each data cell includes a first transistor, a second transistor, and a data element. The first transistor may have a column gate and a channel, and the second transistor may include a row gate that crosses over the column gate, under the column gate, or both. The second transistor may also include another channel, a source disposed near a distal end of a first leg, and a drain disposed near a distal end of a second leg. The column gate may extend between the first leg and the second leg. The channel of the second transistor may be connected to the channel of the first transistor, and the data element may be connected to the source or the drain.

Abstract: Embodiments of an apparatus and methods for improving multi-gate device performance are generally described herein. Other embodiments may be described and claimed.

Abstract: Disclosed are methods, systems and devices, including a method that includes the acts of forming a semiconductor fin, forming a sacrificial material adjacent the semiconductor fin, covering the sacrificial material with a dielectric material, forming a cavity by removing the sacrificial material from under the dielectric material, and forming a gate in the cavity.

Abstract: A monolithic integrated circuit fabricated on a semiconductor die includes a control circuit and a first output transistor having segments substantially equal to a first length. A second output transistor has segments substantially equal to a second length. The first and second output transistors occupy an L-shaped area of the semiconductor die, the L-shaped area having first and second inner sides that are respectively disposed adjacent first and second sides of the control circuit. At least one of the first and second output transistors is coupled to the control circuit. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: A method of manufacturing a semiconductor device, including forming a plurality of gate structures on a substrate, the gate structures each including a hard mask pattern stacked on a gate conductive pattern, forming an insulating layer pattern between the gate structures at least partially exposing a top surface of the hard mask pattern, forming a trench that exposes at least a top surface of the gate conductive pattern by selectively removing the hard mask pattern, and forming a silicide layer on the exposed gate conductive pattern.

Abstract: Fin field-effect-transistor (finFET) structures having two dielectric thicknesses are generally described.

Abstract: Disclosed are embodiments of an improved multi-gated field effect transistor (MUGFET) structure and method of forming the MUGFET structure so that it exhibits a more tailored drive current. Specifically, the MUGFET incorporates multiple semiconductor fins in order to increase effective channel width of the device and, thereby, to increase the drive current of the device. Additionally, the MUGFET incorporates a gate structure having different sections with different physical dimensions relative to the semiconductor fins in order to more finely tune device drive current (i.e., to achieve a specific drive current). Optionally, the MUGFET also incorporates semiconductor fins with differing widths in order to minimize leakage current caused by increases in drive current.

Abstract: A multi-gate device having a T-shaped gate structure is generally described. In one example, an apparatus includes a semiconductor substrate, at least one multi-gate fin coupled with the semiconductor substrate, the multi-gate fin having a gate region, a source region, and a drain region, the gate region being positioned between the source and drain regions, a gate dielectric coupled to the gate region of the multi-gate fin, a gate electrode coupled to the gate dielectric, the gate electrode having a first thickness and a second thickness, the second thickness being greater than the first thickness, a first spacer dielectric coupled to a portion of the gate electrode having the first thickness, and a second spacer dielectric coupled to the first spacer dielectric and coupled to the gate electrode where the second spacer dielectric is coupled to a portion of the gate electrode having the second thickness.

Abstract: Disclosed are methods, systems and devices, including a system, having a memory device. In some embodiments, the memory device includes a plurality of fin field-effect transistors disposed in rows, a plurality of insulating fins each disposed between the rows, and a plurality of memory elements each coupled to a terminal of a fin field-effect transistor among the plurality of fin field-effect transistors.

Abstract: A method of fabricating a semiconductor device forms a micro-sized gate, and mitigates short channel effects. The method includes a pull-back process to form the gate on a substrate. The method also includes forming inner and outer spacers on the gate that are asymmetric to one another with respect to the gate, and using the spacers in forming junction regions in the substrate on opposite sides of the gate. In particular, the inner and outer spacers are formed on opposite sides of the gate so as to have different thicknesses at the bottom of the gate. The inner and outer junction regions are formed by doping the substrate before and after the spacers are formed. Thus, the inner and outer junction regions have extension regions under the inner and outer spacers, respectively, and the extension regions have different lengths.

Abstract: A semiconductor device includes: a channel region extending substantially perpendicular to a main surface of a semiconductor substrate; a first diffusion layer provided on a bottom of the channel region; a second diffusion layer provided on a top of the channel region; a first gate electrode that extends substantially perpendicular to the main surface of the semiconductor substrate and that is provided on a side of the channel region through a gate insulation film; and a second gate electrode that extends substantially parallel to the main surface of the semiconductor substrate and that is connected to the top of the first gate electrode, wherein a planar position of the second gate electrode is offset relative to a planar position of the first gate electrode.

Abstract: Disclosed herein are embodiments of an improved method of forming p-type and n-type MUGFETs with high mobility crystalline planes in high-density, chevron-patterned, CMOS devices. Specifically, semiconductor fins are formed in a chevron layout oriented along the centerline of a wafer. Gates are formed adjacent to the semiconductor fins such that they are approximately perpendicular to the centerline. Then, masked implant sequences are performed, during which halo and/or source/drain dopants are implanted into the sidewalls of the semiconductor fins on one side of the chevron layout and then into the sidewalls of the semiconductor fins on the opposite side of the chevron layout. The implant direction used during these implant sequences is substantially orthogonal to the gates in order to avoid mask shadowing, which can obstruct dopant implantation when separation between the semiconductor fins in the chevron layout is scaled (i.e., when device density is increased).

Abstract: A first dielectric layer is formed over a PFET gate and an NFET gate, and lithographically patterned to expose a PFET area, while covering an NFET area. Exposed PFET active area is etched and refilled with a SiGe alloy, which applies a uniaxial compressive stress to a PFET channel. A second dielectric layer is formed over the PFET gate and the NFET gate, and lithographically patterned to expose the NFET area, while covering the PFET area. Exposed NFET active area is etched and refilled with a silicon-carbon alloy, which applies a uniaxial tensile stress to an NFET channel. Dopants may be introduced into the SiGe and silicon-carbon regions by in-situ doping or by ion implantation.

Abstract: A method for manufacturing an EEPROM cell including a dual-gate MOS transistor. The method includes the steps of providing a semiconductor substrate covered with a stack of first and second layers, forming at least one first opening in the second layer, forming, in the first layer, a second opening continuing the first opening, enlarging the first opening by isotropic etching, forming a first doped region in the substrate by implantation through the first enlarged opening, the first doped region taking part in the forming of the transistor drain or source, forming, in the third opening, a thinned-down insulating portion thinner than the first layer, and forming the gates of the MOS transistor at least partially extending over the thinned-down insulating portion.

Abstract: A semiconductor memory device has a substrate having a semiconductor layer, an n-type semiconductor region formed beneath a main surface of the semiconductor layer, a plurality of cell gates being aligned at a space from each other and including a gate insulating film formed on the main surface of the semiconductor layer, a charge storage layer formed on the gate insulating film, a charge block layer formed on the charge storage layer and a control gate electrode formed on the charge block layer, an insulating film between cells formed on the main surface of the semiconductor layer between the cell gates, and a carbon accumulation region formed in the insulating film between the cells and has a maximum concentration of a carbon element in a region within 2 nm from an interface between the semiconductor layer and the insulating film between the cells.

Abstract: A metal-oxide-semiconductor field effect transistor (MOSFET) has a body layer that follows the contour of exposed surfaces of a semiconductor substrate and contains a bottom surface of a shallow trench and adjoined sidewalls. A bottom electrode layer vertically abuts the body layer and provides an electrical bias to the body layer. A top electrode and source and drain regions are formed on the body layer. The thickness of the body layer is selected to allow full depletion of the body layer by the top electrode and a bottom electrode layer. The portion of the body layer underneath the shallow trench extends the length of a channel to enable a high voltage operation. Further, the MOSFET provides a double gate configuration and a tight control of the channel to enable a complete pinch-off of the channel and a low off-current in a compact volume.

Abstract: The present invention provides an integrated circuit with a floating body transistor comprising two source/drain regions and a floating body region arranged between the two source/drain regions comprising: a back gate electrode separated from the floating body by a first dielectric layer; a control gate electrode, separated from the floating body by a second dielectric layer and overlying the back gate electrode; and a third dielectric layer arranged between the back gate electrode and the control gate electrode. The present invention provides also a method of manufacturing an integrated circuit and a method of operating an integrated circuit.

Abstract: Embodiments relate to an LDMOS semiconductor device mask that may reduce current leakage under a gate-off condition. According to embodiments, an LDMOS semiconductor device mask may include a moat mask to define a moat region, an NDT mask to define an N drift region, a PDT mask to define a P drift region, and a gate mask to form a gate. According to embodiments, a PDT mask may be configured to expose a field region of a semiconductor device.

Abstract: A method for manufacturing a cell of a non-volatile electrically erasable and programmable memory including a dual-gate MOS transistor. The method includes the steps of providing a semiconductor substrate covered with an insulating layer including a thinned down portion and having a first surface common with the substrate and a second surface opposite to the first surface; and incorporating nitrogen at the level of the second surface, whereby the maximum nitrogen concentration is closer to the second surface than to the first surface.