Spin coating in semiconductor manufacturing

Abstract

Techniques for spin coating in semiconductor fabrication are disclosed. An apparatus is provided that includes a base coupled with each of an inner wall, a partition wall, and an outer wall. The inner wall surrounds the axis of rotation of the chuck. The chuck is adapted to rotate the wafer during a coating operation. The partition wall surrounds the inner wall. A partition wall at least partially divides the interior of the device into a liquid chamber and a gas chamber. The outer wall surrounds the partition wall. The device includes a partition cover coupled with the inner wall but not with the partition wall. The partition cap is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber. The partition cover and the partition wall are adapted to maintain the gas chamber substantially free of excess coating material during the coating operation.

Description

Background Art

[0001] Embodiments presented in this disclosure relate to the field of semiconductor devices. More specifically, embodiments disclosed herein relate to techniques for spin coating during the fabrication of semiconductor devices.

[0002] Semiconductor devices are widely used in the control of electrical power, ranging from dimmer electric motor speed control to high voltage DC power transmission. For example, thyristors are used in alternating current (AC) power control applications. Thyristors can be operated as electrical power switches because thyristors are characterized by the ability to quickly switch from a non-conductive state to a conductive state. In operation, the thyristor is turned on, switching from a high impedance state to a low impedance state. This is achieved by applying a voltage between the gate and the cathode and allowing current to travel from the gate to the cathode. Summary of the invention

[0003] One embodiment presented in the present disclosure provides a device for spin coating. The device includes a base coupled to each of an inner wall, a partition wall, and an outer wall. The device also includes an inner wall that substantially surrounds the axis of rotation of a chuck. The chuck is suitable for holding and rotating a wafer during a coating operation, wherein a coating material is dispensed onto the wafer. The device also includes a partition wall that substantially surrounds the inner wall. The partition wall at least partially divides the interior of the device into a liquid chamber and a gas chamber. The device also includes an outer wall that substantially surrounds the partition wall.

[0004] The device also includes a partition cover coupled to the inner wall but not to the partition wall. The partition cover substantially surrounds the rotation axis of the chuck. The partition cover has a top surface and a bottom surface. The top surface is at least partially convex, and the bottom surface is at least partially concave. The partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber. The partition cover and the partition wall are adapted to keep the gas chamber substantially free of excess coating material during the coating operation.

[0005] Another embodiment provides a spin coater. The spin coater includes a chuck suitable for holding and rotating a wafer during a coating operation, wherein a coating material is dispensed onto the wafer. The spin coater also includes a motor suitable for rotating the chuck at a specified rotational speed during the coating operation. The spin coater also includes a dispenser suitable for dispensing the coating material onto the wafer during the coating operation. The dispenser is disposed above the chuck. The spin coater also includes a catch basin having an outer cover and including a separator cover. The separator cover is suitable for isolating liquid and gas from each other in the catch basin. The separator cover is at least partially concave-convex.

[0006] Yet another embodiment provides a method of spin coating. The method includes: providing a wafer in which a plurality of semiconductor devices are manufactured. The wafer includes an isolation structure that laterally isolates the semiconductor devices from each other in the wafer. The method also includes: performing one or more photolithography operations on the wafer. The one or more photolithography operations include applying a coating material to the wafer using a spin coater. The spin coater includes a water collection tank, and the water collection tank has an outer cover and includes a separator cover. The separator cover is suitable for separating liquid and gas from each other in the water collection tank. The separator cover is at least partially concave-convex. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An apparatus for spin coating in semiconductor manufacturing is depicted according to one embodiment presented in the present disclosure.

[0008] Figure 2A-2B Depicted are cross-sectional views of a semiconductor device on a wafer during different stages of a manufacturing process according to one embodiment presented in the present disclosure.

[0009] Figure 3A-3B Depicted is a cross-sectional view of a semiconductor device during a photolithography operation in a manufacturing process according to one embodiment presented in the present disclosure.

[0010] Figure 4 is a flow chart depicting a method of fabricating a semiconductor device according to one embodiment presented in the present disclosure.

[0011] Figure 5 is a flow chart depicting a method for photolithography according to one embodiment presented in the present disclosure.

[0012] Figure 6 is a flow chart depicting a method of applying a coating material to a wafer according to one embodiment presented in the present disclosure. DETAILED DESCRIPTION

[0013] Embodiments presented in the present disclosure provide techniques for spin coating using an apparatus. Depending on the embodiment, the apparatus itself can be a component of a spin coater, or constitute a spin coater. The apparatus includes a base coupled to each of an inner wall, a partition wall, and an outer wall. The apparatus includes an inner wall that substantially surrounds an axis of rotation of a chuck. The chuck is adapted to hold and rotate a wafer during a coating operation in which a coating material is dispensed onto the wafer. The coating operation can be part of a process to form a semiconductor device, such as a thyristor or a diode, on a wafer.

[0014] In one embodiment, the device includes a partition wall that substantially surrounds the inner wall. The partition wall at least partially divides the interior of the device into a liquid chamber and a gas chamber. The device also includes an outer wall that substantially surrounds the partition wall. The device also includes a partition cover coupled to the inner wall but not to the partition wall. The partition cover substantially surrounds the rotation axis of the chuck.

[0015] The partition cover has a top surface and a bottom surface. The top surface is at least partially convex, and the bottom surface is at least partially concave. The partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber. The partition cover and the partition wall are adapted to keep the gas chamber substantially free of excess coating material during a coating operation.

[0016] In some embodiments, the thickness measure of the spacer cover is reduced by increasing the concavity measure of the bottom surface of the spacer cover. Doing so increases the concavity measure of the spacer cover while reducing the plano-convexity measure of the spacer cover. Depending on the embodiment, the convexity measure of the top surface of the spacer cover is reduced or remains unchanged.

[0017] With reference to the types of measures described herein, such as concavo-convexity, plano-convexity, concavity, etc., each such type of measure can represent the degree to which a spacer cover or a portion thereof is close to a reference volume or shape or a portion thereof corresponding to that type of measure. Depending on the embodiment, the degree of closeness can be determined based on the volume, cross-sectional area, or surface area of ​​the spacer cover and / or the reference volume or shape.

[0018] For a given type of measure, the reference volume or shape may have any arbitrary measure that is greater than the corresponding measure of the spacer cover both before and after the thickness of the spacer cover is reduced. Alternatively, for a given type of measure, the reference volume or shape may have any arbitrary measure that is less than the corresponding measure of the spacer cover both before and after the thickness of the spacer cover is reduced.

[0019] The reduced thickness of the partition cover expands the airway between the liquid chamber and the gas chamber. This reduces the speed at which the gas is allowed to flow from the liquid chamber to the gas chamber when the gas is pumped through the device via a pump during the coating operation. The reduced speed at which the gas is allowed to flow also reduces the speed at which the excess coating material is allowed to flow in the liquid chamber. This in turn increases the rate of chemical interaction between the excess coating material and the solvent. The increased rate of chemical interaction reduces the rate of deposition of the excess coating material in the device. Advantageously, the frequency of needing to clean and / or replace the device is reduced. As a result, the operational durability measurement of the device for spin coating is increased.

[0020] Although embodiments are described herein with reference to specific examples of semiconductor devices for purposes of illustration and explanation, this is not intended to limit the scope of the disclosed embodiments. The specific example constitutes a thyristor, a known device based on four different semiconductor layers that are arranged in electrical series and are generally formed within a single crystal substrate such as silicon. The thyristor includes four layers of alternating polarity types (positive (positive, P) or negative (negative, N)) of alternating types of material, wherein the layers are arranged between an anode and a cathode. Those skilled in the art will recognize that, more generally, other types of power switching devices and semiconductor devices can be manufactured using the techniques disclosed herein. For example, diodes such as transient-voltage-suppression (TVS) diodes can be manufactured.

[0021] Figure 1 An exterior view 102 is included that depicts an apparatus 101 for spin coating in semiconductor manufacturing according to one embodiment. In some embodiments, and as depicted in interior view 104, the apparatus 101 includes a sump 108 and a platform disposed at or substantially near the center of the sump 108.

[0022] Depending on the embodiment, some or all of the sump and / or the device may be made of plastic and may constitute replaceable components of the spin coater. In addition, the spin coater may support one or more different types of film delivery methods such as arm drive and belt drive. Additionally or alternatively, the spin coater may support different types of control methods such as single chip microcomputer control and industrial computer control.

[0023] The platform is also referred to as a chuck 112 and is shown in view 1101. Wafer 116 may be placed on chuck 112 such that the bottom surface of wafer 116 is substantially in contact with the surface of chuck 112. A vacuum may be applied to the bottom surface of wafer 116 to secure wafer 116 to chuck 112 even as chuck 112 rotates during the spin coating process.

[0024] In some embodiments, the diameter of the chuck 112 may be smaller than the diameter of the wafer 116. The chuck 112 may be rotated via a shaft 114 operably connected to the chuck 112, and the shaft 114 may in turn be rotated by operation of an electric motor (not shown).

[0025] View 110 2-4A series of steps during spin coating are shown. At the first step represented by view 1102, coating material 118 is applied to the upper side of wafer 116. More specifically, a specified amount of coating material 118 can be applied via a dispenser (not shown) at or substantially near the center of the upper side of wafer 116. The specified amount of coating material 118 can be adjusted by controlling the flow rate through the dispenser, and the flow rate can be controlled via the pressure in the reservoir for the coating material.

[0026] At least in some embodiments, the coating material 118 is a photoresist material, and the photoresist material is a liquid. The photoresist material may include one or more components, including a resin that provides physical properties, a sensitizer with a photoactive compound, and / or a solvent that helps maintain the liquid form of the photoresist material. The first step is also called deposition.

[0027] In one embodiment, coating material 118 may be applied to wafer 1116 as a first step in a photolithography process. Coating material 118 is applied so that an image can be developed on the substrate of wafer 116. Coating material 118 may be applied while wafer 116 is stationary or rotated by chuck 112 at a relatively low speed.

[0028] At the second step, represented by view 1103, the rotation speed of the chuck 112 is increased, causing the coating material 118 to spread from the center of the upper side of the wafer 116 toward the circumference of the wafer 116 via centrifugal force. This causes the upper side of the wafer 116 to be substantially coated with a relatively thin layer of the coating material 118. The relatively high rotation speed at the second step can promote thickness uniformity of the layer across the upper side of the wafer 116. The second step is also referred to as spin-up.

[0029] At the third step represented by view 1104, the rotation speed of chuck 112 is substantially maintained for a specified duration. The third step is also referred to as spin-off. During the second and / or third steps, excess coating material is spun off from the wafer. In some embodiments, the wafer is thereby spun dry.

[0030] During the first, second and / or third steps, some or all of the solvent components of the coating material 118 evaporate, causing the coating material to solidify on the upper surface of the wafer 116. In order to obtain the desired level of layer thickness, certain parameters of the spin coating can be adjusted. Examples of these parameters include, but are not limited to, the amount of coating material 118, the rotation speed of the chuck 112, and / or a specified duration.

[0031] Other steps are also widely contemplated. For example, in some embodiments, baking may be suitable for promoting evaporation. Additionally or alternatively, rinsing of the wafer may also be performed via a spraying operation using a solvent. Rinsing may wash away coating material deposited at or near a specified area of ​​the wafer, such as the circumference of the wafer. In some embodiments, this solvent is a separate solvent that is not confused with the solvent component of the coating material 118.

[0032] In some embodiments, excess coating material spun off from the wafer 116 during spin coating is discharged from the sump 108 via the liquid outlet 120 of the sump 108. However, at least some of the excess coating material may be deposited on the inner surface of the sump, forming a solidified residue. The accumulation of such deposits over time may begin to adversely affect the subsequent use of the device for spin coating. In some instances, the liquid outlet may be partially or completely blocked by such deposits. In addition, attempts to clean such deposits from the sump 108 and / or to clear the liquid outlet may prove difficult. In some instances, the sump 108 or the device 101 or parts thereof may even need to be replaced.

[0033] Thus, in one embodiment, and as shown in the interior view 104, the device has a base 124 of the sump 108, wherein the base 124 is coupled to each of the inner wall 126, the divider wall 128, and the outer wall 130. The inner wall 126 substantially surrounds the axis of rotation of the chuck 112. The divider wall 128 substantially surrounds the inner wall 126. In addition, the divider wall 128 at least partially divides the interior of the device into a liquid chamber 132 and a gas chamber 134. The outer wall 130 substantially surrounds the divider wall 128.

[0034] The apparatus further includes a separation cover 138. The separation cover 138 is coupled to the inner wall 126 but not to the separation wall 128. The separation cover 138 substantially surrounds the axis of rotation of the chuck 112. The separation cover 138 has a top surface and a bottom surface. According to some embodiments, the top surface is at least partially convex and the bottom surface is at least partially concave. The separation cover 138 is adapted to divert excess coating material to flow through the separation wall 128 and into the liquid chamber 132. The separation cover 138 and the separation wall 128 are adapted to keep the gas chamber 134 substantially free of excess coating material during a coating operation.

[0035] Factors that affect the measure of drainage efficiency in sump 108 include, but are not limited to, the shape of sump 108, the flow rate of the solvent, the injection time of the solvent, the volume of air drawn through device 101, and the measure of effectiveness of sump 108 in separating gas and liquid. Of these factors, all but the first and last factors are readily adjustable, at least in some embodiments.

[0036] In some embodiments, after approximately three thousand coating operations have been performed using the apparatus, even partially or mostly optimal settings of the adjustable factors still result in gas outlet 122 being at least partially blocked by the accumulation of residue within sump 108. This blockage drastically reduces the rate of air flow through apparatus 101 and gas outlet 122. In practice, sump 108 and / or apparatus 101 need to be replaced after only approximately two thousand five hundred coating operations have been performed.

[0037] Blockage is typically accompanied by residue accumulation on both the base of the liquid chamber 132 and the base of the gas chamber 134, with a greater amount of residue typically being accumulated on the former. During the coating operation, when excess coating material is sucked near and / or through the airway between the bottom of the partition cover 138 and the top of the partition wall 128, the excess coating material may be deposited on the bottom of the partition cover 138 and / or the top of the partition wall 128. Due to the accumulation of residue, the height of the partition wall 128 increases, and the size of the airway is also reduced. Eventually, the gas outlet 122 and / or the liquid outlet 120 are partially or mostly blocked by residue.

[0038] As shown in the close-up view 106 relative to the interior view 104, the thickness measurement of the separator cover 138 is reduced, which is represented by the form of the reduction 144. The scraping operation can be used to reduce the thickness measurement. Doing so increases the rate of air flow through the device 101 by expanding the ventilation path through the device 101. In some embodiments, a portion of the bottom surface of the separator cover 138 is scraped, as described further below.

[0039] In at least some embodiments, the outer cover 136 has a diameter of about 288.5 mm and / or a circumference of about 906.5 mm, while the separator cover 138 has a diameter of about 238 mm and / or a circumference of about 747.5 mm. In addition, the device 101 has a height of about 111 mm, while the separator cover 138 has a height of about 54.5 mm. At least in such embodiments, before scraping, a portion of the bottom surface of the separator cover 138 (depending on the embodiment) is flat or substantially aligned with at least a portion of the outer surface of a sphere having a radius of about 120 mm in one or more dimensions. This portion is represented in the close-up view 106 as the bottom surface 140 before reducing the thickness of the separator cover 138.

[0040] On the other hand, after shaving a portion of the bottom surface to reduce its width to about 3.56 millimeters, the portion is substantially aligned in one or more dimensions with at least a portion of the outer surface of a sphere having a radius now reduced to about 60 millimeters. In close-up view 106, the portion is represented as bottom surface 142 after reducing the thickness of separator cover 138. Other measurements and dimensions are broadly contemplated without departing from the scope of the present disclosure.

[0041] In some embodiments, the thickness measure is reduced by increasing the concavity measure of at least a portion of the bottom surface of the spacer cover. Doing so can increase the concavity measure of the spacer cover 138 while reducing the plano-convexity measure of the spacer cover 138. Depending on the embodiment, the plano-convexity measure of at least a portion of the top surface of the spacer cover 138 can be reduced or can remain unchanged.

[0042] As shown in the interior view 104, the reduction in thickness 144 of at least a portion of the separator cover enlarges the gas passage 146 between the liquid chamber 132 and the gas chamber 134. Doing so reduces the rate at which gas flows from the liquid chamber 132 to the gas chamber 134 as the gas is pumped through the device 101 via the pump during a coating operation.

[0043] In some embodiments, the reduced velocity of the gas flow also reduces the velocity at which the excess coating material flows in the liquid chamber 132. This in turn increases the rate of chemical interaction between the excess coating material and the solvent. Depending on the embodiment, the solvent may be a solvent component of the excess coating material and / or a separate solvent. The separate solvent may be a developer solvent and / or a cleaning solvent.

[0044] Advantageously, the increased rate of chemical interaction has the effect of reducing the rate of deposition of excess coating material within the device 101. The operational durability measure of the device is thereby increased. This increase may be due to a reduced frequency of needing to clean and / or replace the device. In a particular embodiment, the excess coating material is unexposed photoresist and the solvent is xylene.

[0045] By using the techniques described herein, at least in some embodiments, at least four thousand coating operations may be performed without replacing the sump 108 and / or the apparatus 101, as opposed to requiring replacement after only approximately two thousand five hundred coating operations have been performed. This corresponds to a sixty percent increase in the operational durability of the apparatus 101. For example, it has been observed in practice that even after three thousand coating operations have been performed with the apparatus described herein, the residue buildup is still at an acceptable level.

[0046] In some embodiments, and as shown in the internal view 104, the device 101 includes an outer cover 136, which is a cover of at least the liquid chamber 132. The outer cover 136 substantially surrounds the rotation axis of the chuck 112. The outer cover 136 is disposed above the liquid chamber 132 and the partition wall 128. The partition cover 138 is at least partially disposed above the liquid chamber 132. On the other hand, the outer cover 136 is at least partially disposed above the gas chamber 134. In addition, the outer cover 136 is at least partially disposed above the partition cover 138.

[0047] According to one embodiment, the base 124 defines a liquid outlet 120 for the liquid chamber 132 and also defines a gas outlet 122 for the gas chamber 134. The outer cover 136 can define one or more inlets, and each inlet can be a liquid inlet and / or a gas inlet. In one embodiment, the gas outlet 122 is operably connected to a pump (not shown). The pump is adapted to allow air to be drawn into the device 101 via the inlet and drawn out of the device 101 via the gas outlet 122. In a particular embodiment, the air is clean room air and is drawn into an exhaust system (not shown). Excess coating material and / or solvent is at least substantially discharged from the device 101 via the liquid outlet 120.

[0048] In some embodiments, the device 101 further comprises a motor adapted to rotate the chuck at a specified rotational speed during the coating operation. Additionally or alternatively, the device 101 comprises a dispenser disposed above the chuck 112. The dispenser is adapted to dispense the coating material onto the wafer 116 during the coating operation.

[0049] Figure 2A-2B Depicted are cross-sectional views of semiconductor devices on a wafer during different stages of a manufacturing process according to one embodiment. The cross-sectional views correspond to a vertical cross-section of the wafer, ie, a cross-section perpendicular to the wafer face.

[0050] like Figure 2A As shown, in a first stage 210 of the manufacturing process, a wafer 202 includes a substrate layer 212, wherein the substrate layer 212 includes silicon. Both the top surface and the bottom surface of the substrate layer 212 are doped using a dopant 216 and a doping mask 214. As used herein, the top surface is also referred to as an upper surface or front surface, and the bottom surface is also referred to as a lower surface or back surface. According to one embodiment, the doping mask 214 includes an oxide.

[0051] The substrate layer 212 is N -In the case of a substrate layer, the dopant 216 used is a P dopant. An example of a P dopant is boron, and an example of an N dopant is phosphorus. As used herein with reference to dopants, a symbol in a superscript or the absence of a symbol indicates a relative doping concentration, wherein a plus sign indicates a higher relative doping concentration, a minus sign indicates a lower relative doping concentration, and the absence of a symbol indicates an intermediate relative doping concentration. Even if the symbol is not in a superscript, the symbols herein may be used interchangeably with the same symbol in a superscript. Multiple plus or minus signs in a row may be used to indicate successively higher or lower relative doping concentrations.

[0052] According to one embodiment, the substrate layer 212 of the wafer 202 is doped with a dopant 216, producing the wafer 202 in the second stage 220 of the manufacturing process. As shown, the wafer 202 of the second stage 220 includes an isolation structure 222, which isolates the semiconductor devices from each other laterally in the wafer. In the case of using a P dopant, the isolation structure is a P isolation structure. Generally, once the dopant 216 diffused from the top and bottom surfaces of the wafer 202 meets, the isolation structure 222 is formed. In other words, to form the isolation structure 222, each of the top and bottom surfaces of the substrate layer 212 is doped with a dopant 216 until the dopant diffused from the top surface meets the dopant diffused from the bottom surface. The point where the diffused dopant meets can generally be adjacent to the vertical center of the wafer 202 in terms of the thickness of the wafer 202.

[0053] In one embodiment, both the top and bottom surfaces of the substrate layer 212 of the wafer 202 may be further doped with a dopant 216 to produce the wafer 202 at the third stage 230 of the manufacturing process. As shown, the wafer 202 at the third stage 230 includes a lower base layer 232 and an upper base layer 234. In the case of using a P dopant, the lower base layer 232 is a P lower base layer, and the upper base layer 234 is a P upper base layer. The upper base layer 234 may then be doped with a different dopant. Doping the upper base layer 234 produces a top layer 236. In the N - In the case of the substrate layer, this dopant is N + dopant, and the top layer 236 is N + Top floor.

[0054] In at least some embodiments, the top layer 236 is smaller in area than the upper base layer 234 from a plan view of the face of the wafer 202, thereby exposing at least a portion of the upper base layer 234. Additionally or alternatively, the substrate layer 212 is thicker than each of the lower base layer 232, the upper base layer 234, and the top layer 236, as well as the isolation structure 222.

[0055] After the top layer 236 is produced, a deep trench 238 is formed for each semiconductor device in the wafer 202. The deep trench 238 is characterized by being formed around the upper base layer 234 of each semiconductor device based on a plan view of the wafer 202. Like this, the deep trench 238 surrounds the upper base layer 234 based on a plan view of the wafer 202. The deep trench 238 can be formed via an etching process such as a silicon etching process.

[0056] In addition, the deep trench 238 partially exposes each of the substrate layer 212, the upper base layer 234, the top layer 236, and the isolation structure 222. Moreover, the substrate layer 212 is exposed only via the deep trench 238. On the other hand, at least in some embodiments, the deep trench 238 does not expose any of the lower base layer 232. Because the deep trench 238 has a cylindrical shape in the wafer 202, according to one embodiment, the deep trench 238 has a semicircular shape based on a cross-sectional view of the wafer 202. However, depending on the type of semiconductor device to be manufactured in the wafer 202, the upper base layer 234 does not necessarily need to be exposed by the deep trench 238. In some alternative embodiments, the upper base layer 234 is not exposed via the deep trench 238 at all. The formation of the deep trench 238 will be described below in conjunction with Figure 3A-3B Further description.

[0057] After forming the deep trench 238, a glass deposit (shown as glass 239) is formed atop one or more electroplating regions on the top surface of the wafer 202. The one or more electroplating regions may include corresponding one or more electroplating regions for each semiconductor device in the wafer 202. In a particular embodiment, the corresponding one or more electroplating regions include the deep trench 238 itself, as well as one or more additional regions in the area surrounded by the deep trench 238 based on a plan view of the wafer 202. According to one embodiment, the glass deposit atop each electroplating region constitutes a corresponding electroplating, and the corresponding electroplating includes electroglass.

[0058] like Figure 2B 2, a cross-sectional view of the wafer 202 during the fifth stage 250 of the manufacturing process shows that the semiconductor device in the wafer 202 is a thyristor 252. In an alternative embodiment, the semiconductor device is a TVS diode. According to one embodiment, the thyristor 252 has terminals including an anode 254, a cathode 256, and a gate 258. The anode 254 is formed on the lower base layer 232, the cathode 256 is formed on the top layer 236, and the gate 258 is formed on the upper base layer 234.

[0059] In one embodiment, each of the lower base layer 232 and the top layer 236 constitutes a respective emitter layer of the thyristor 252. The lower base layer 232 constituting an emitter layer may be the case for certain types of thyristors, such as silicon controlled rectifiers (SCRs). For certain other types of thyristors, such as triacs, the lower base layer does not constitute any emitter layer.

[0060] In addition, the thyristor 252 has PN junctions including a first junction J1 260, a second junction J2 262, and a third junction J3 264. The first junction J1 260 is disposed between the lower base layer 232 and the substrate layer 212. The second junction J2 262 is disposed between the substrate layer 212 and the upper base layer 234. The third junction J3 264 is disposed between the upper base layer 234 and the top layer 236.

[0061] Although for the purpose of illustration and description, reference is made herein to N - The substrate layer describes an embodiment, but this is not intended to limit the scope of the disclosed embodiments. For example, by reversing the corresponding polarity of each dopant disclosed herein, the technology disclosed herein is applicable to P - Alternative Uses of Substrate Layers.

[0062] Figure 3A-3B Depicted are cross-sectional views of a semiconductor device on a wafer during different stages of a manufacturing process according to one embodiment. Each stage may correspond to a corresponding, identical, or different lithography operation. In a particular embodiment, Figure 3A-3B The phase corresponds to the formation of Figure 2A A single lithography operation is performed to form a deep trench 238. The lithography operation is of the type that operates on silicon. In other embodiments, lithography operations that operate on metal are supported.

[0063] like Figure 3A As shown, a substrate layer 312 is provided in a first stage 310 of the manufacturing process. The substrate layer 312 may correspond to Figure 2A Any one or more components of the wafer 202 of the third stage 230. In one embodiment, the substrate layer 312 corresponds to Figure 2A The entirety of the wafer 202 includes the upper base layer 234, the substrate layer 212 and the isolation structure 222. In this embodiment, the substrate layer 312 can be understood in terms of processing as corresponding to the first stage 210 but in Figure 2A The substrate layer 212 of the third stage 230 .

[0064] In a first stage 310, silicon deposition is optionally performed on a substrate layer 312, which itself may include silicon. This silicon deposition results in a silicon layer 322 atop the substrate layer 312 in a second stage 320 of the manufacturing process.

[0065] In the second stage 320, a photoresist coating is applied to the silicon layer 322. Alternatively, if silicon deposition is not performed, the photoresist coating is applied to the substrate layer 312. Applying the photoresist coating results in a photoresist layer 332 over the silicon layer 322 and / or the substrate layer 312 in the third stage 330 of the manufacturing process.

[0066] In the third stage 330, ultraviolet (UV) light 336 is applied to the photoresist layer 332 via pattern exposure using a photomask 334. In some embodiments, one or more alignment keys on the wafer are used to align the photomask with the wafer. More specifically, the photomask can be aligned with the wafer by aligning the reticle of the objective lens of the aligner with the one or more alignment keys. Depending on the embodiment, the aligner can be a contact aligner, a proximity aligner and / or a projection aligner. Applying UV light to the photoresist layer 332 produces a photoresist layer 332 with an exposed area 342 in the fourth stage 340 of the manufacturing process.

[0067] At the fourth stage 340, a developer solvent 344 is applied to the photoresist layer 332 having the exposed areas 342. To this end, the developer solvent 344 is of a positive photoresist type in order to remove the exposed areas 342. In an alternative embodiment, the developer solvent 344 may be of a negative photoresist type to remove the unexposed areas of the photoresist layer 332, provided that a different photomask constituting the inverse of the photomask 334 is used at the third stage 330. Applying the developer solvent 344 to the photoresist layer 332 produces the photoresist layer 332 having the exposed areas removed at the fifth stage 350 of the manufacturing process.

[0068] At the fifth stage 350, chemical etching is performed on the silicon layer 322 based on the photoresist layer 332 having the exposed areas removed. Performing the chemical etching results in the silicon layer 322 being etched at the sixth stage 360 ​​of the manufacturing process.

[0069] At the sixth stage 360, photoresist removal is performed on the wafer. Performing the photoresist removal results in an etched silicon layer 322 having the photoresist layer removed at the seventh stage 370 of the fabrication process.

[0070] In the seventh stage 370, an insulator is added to the wafer. In some embodiments, the insulator can be silicon dioxide. Adding the insulator to the wafer produces an etched silicon layer 322 having an insulator region 382 in the eighth stage 380 of the manufacturing process.

[0071] If any additional photoresist layers remain to be processed, the eighth stage 380 reverts to the first stage 310 to repeat the process for the next photoresist layer to be processed. If no additional photoresist layers remain to be processed, no processing is performed in the eighth stage 380, and the processing can be considered complete after the seventh stage 370. By performing the Figure 3A-3B At each stage of the manufacturing process, the deep trench 238 is formed in Figure 2A on the chip 202.

[0072] Figure 4 4 is a flow chart depicting a method 400 for manufacturing a semiconductor device according to one embodiment. As shown, the method 400 begins at step 410, where a substrate layer of a wafer is provided. At step 420, an isolation structure of the wafer is formed by doping a first portion of the substrate layer. At step 430, a lower base layer of the wafer is formed by doping a second portion of the substrate layer. At step 440, an upper base layer of the wafer is formed by doping a third portion of the substrate layer. At step 450, a top layer is formed by doping only a portion of the upper base layer.

[0073] At step 460, one or more photolithography operations are used to form corresponding deep trenches around the upper base layer of each semiconductor device to be fabricated on the wafer. Step 460 is described below in conjunction with Figure 5 Further described. At step 470, a corresponding electroplated glass deposit is formed atop each electroplated region of each semiconductor device. After step 470, method 400 terminates.

[0074] Figure 5 is a flow chart depicting a method 500 for photolithography according to one embodiment. As shown, the method 500 begins at step 510, where a wafer for manufacturing semiconductor devices is provided. The wafer includes an isolation structure that laterally isolates the semiconductor devices from each other in the wafer. At step 520, a photolithography operation is performed on the wafer. The photolithography operation includes applying a coating material to the wafer using a spin coater.

[0075] In one embodiment, the spin coater includes a sump. The sump has an outer cover and carries a separator cover adapted to isolate liquid and gas in separate chambers in the sump. The separator cover is at least partially concave-convex to reduce the deposition rate of excess coating material in the sump. The rate is at least reduced relative to the following separator cover, which is less concave-convex and more plano-convex relative to the aforementioned separator cover. Step 520 is described below in conjunction with Figure 6 After step 520, method 500 terminates.

[0076] Figure 6 is a flow chart depicting a method 600 for applying a coating material to a wafer according to one embodiment. The method 600 corresponds to Figure 5 Some or all of step 520. Figure 6 As shown, method 600 begins at step 610, where a deposition operation is performed by dispensing a coating material onto a wafer. The wafer is held by a chuck of a spin coater, and the spin coater includes a sump.

[0077] In one embodiment, the sump has an outer cover and includes a separator cover adapted to isolate liquid and gas in separate chambers in the sump. The separator cover is at least partially concave-convex to reduce the deposition rate of excess coating material in the sump. The deposition rate is reduced at least relative to a second separator cover that is less concave-convex and more plano-convex relative to the (first) separator cover. At step 620, a rotational acceleration operation is performed using a motor to increase the rotational speed of the chuck.

[0078] At step 630, the spin-off operation is performed by maintaining the rotational speed of the chuck for a specified duration to spin the excess coating material out of the wafer and evaporate the solvent component of the coating material. The excess coating material is directed by the partition cover to flow into the liquid chamber of the sump. The excess coating material is substantially discharged from the liquid chamber via the liquid outlet for the liquid chamber. After step 630, method 600 terminates.

[0079] Further embodiments are described as follows. One embodiment provides a device for spin coating. The device includes a base coupled to each of an inner wall, a partition wall, and an outer wall. The device also includes an inner wall that substantially surrounds the axis of rotation of the chuck. The chuck is adapted to hold and rotate the wafer during a coating operation in which a coating material is dispensed onto the wafer. The device also includes a partition wall that substantially surrounds the inner wall. The partition wall at least partially divides the interior of the device into a liquid chamber and a gas chamber. The device also includes an outer wall that substantially surrounds the partition wall.

[0080] The device also includes a partition cover coupled to the inner wall but not to the partition wall. The partition cover substantially surrounds the rotation axis of the chuck. The partition cover has a top surface and a bottom surface. The top surface is at least partially convex, and the bottom surface is at least partially concave. The partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber. The partition cover and the partition wall are adapted to keep the gas chamber substantially free of excess coating material during the coating operation.

[0081] In some embodiments, the thickness measure of the spacer cover is reduced by increasing the concavity measure of the bottom surface of the spacer cover. This increases the concavity measure of the spacer cover while reducing the plano-convexity measure of the spacer cover. The convexity measure of the top surface of the spacer cover is reduced or remains unchanged.

[0082] In certain embodiments, the reduced thickness of the partition cover expands the air passage between the liquid chamber and the gas chamber. This reduces the speed at which gas flows from the liquid chamber to the gas chamber when the gas is pumped through the device via a pump during the coating operation. The reduced speed of gas flow also reduces the speed at which excess coating material flows in the liquid chamber. This in turn increases the rate of chemical interaction between the excess coating material and the solvent.

[0083] Advantageously, the deposition rate is thus reduced in terms of excess coating material within the device. Since the frequency of needing to clean or replace the device is reduced, a measure of the operational durability of the device is increased. In some embodiments, the excess coating material is a polymer, wherein the polymer may be unexposed photoresist, and the solvent may be xylene.

[0084] In some embodiments, the device further comprises an outer cover, which is a cover of the liquid chamber. The outer cover substantially surrounds the rotation axis of the chuck. In addition, the outer cover is disposed above the liquid chamber and the partition wall. The partition cover is at least partially disposed above the liquid chamber. On the other hand, the outer cover is at least partially disposed above the gas chamber. In addition, the outer cover is at least partially disposed above the partition cover.

[0085] In some embodiments, the base defines a liquid outlet for the liquid chamber and also defines a gas outlet for the gas chamber. The outer cover defines an inlet including a liquid inlet or a gas inlet. The gas outlet is operably connected to a pump that is adapted to allow air to be drawn into the device via the inlet and drawn out of the device via the gas outlet. The air can be clean room air, and the air can be drawn into an exhaust system. Each of the excess coating material and the solvent for the excess coating material can be at least substantially discharged from the device via the liquid outlet.

[0086] In some embodiments, the spin coating device is a sump, and the sump constitutes a component of the spin coater. The device also includes one or more of a motor and a distributor. The motor is suitable for rotating the chuck at a specified rotational speed during the coating operation. The distributor is suitable for distributing the coating material onto the wafer during the coating operation. The distributor can be arranged above the chuck. The coating operation is part of a process for forming a semiconductor device on the wafer. The semiconductor device can include a thyristor or a diode. The diode can be a TVS diode.

[0087] Another embodiment provides a spin coater. The spin coater includes a chuck adapted to hold and rotate a wafer during a coating operation, wherein a coating material is dispensed onto the wafer. The spin coater also includes a motor adapted to rotate the chuck at a specified rotational speed during the coating operation. The spin coater also includes a dispenser adapted to dispense the coating material onto the wafer during the coating operation. The spin coater also includes a sump having an outer cover and including a separator cover. The separator cover is adapted to isolate liquid and gas from each other in the sump. The separator cover is at least partially concave-convex.

[0088] In some embodiments, the separator cover is a first separator cover that is at least partially concave-convex to reduce the deposition rate of excess coating material in the sump. The rate is at least reduced relative to a second separator cover that is at least partially plano-convex. The second separator cover is less concave-convex and more plano-convex than the first separator cover.

[0089] In some embodiments, the sump includes a base coupled to each of the inner wall, the partition wall, and the outer wall. The sump also includes an inner wall that substantially surrounds the axis of rotation of the chuck. The sump also includes a partition wall that substantially surrounds the inner wall. The partition wall at least partially divides the interior of the sump into a liquid chamber and a gas chamber. The sump also includes an outer wall that substantially surrounds the partition wall.

[0090] In some embodiments, the partition cover is coupled to the inner wall but not to the partition wall. The partition cover substantially surrounds the rotation axis of the chuck. The partition cover may have a top surface and a bottom surface. The top surface is at least partially convex, and the bottom surface is at least partially concave.

[0091] In certain embodiments, the divider cover is adapted to divert excess coating material to flow through the divider wall and into the liquid chamber. The divider cover and divider wall are adapted to maintain the gas chamber substantially free of excess coating material during a coating operation.

[0092] Yet another embodiment provides a spin coating method. The method includes providing a wafer in which a plurality of semiconductor devices are manufactured. The wafer includes an isolation structure that laterally isolates the semiconductor devices from each other in the wafer. The method also includes performing one or more photolithography operations on the wafer. The one or more photolithography operations include applying a coating material to the wafer using a spin coater. The spin coater includes a sump, and the sump has an outer cover and includes a separator cover. The sump is suitable for isolating a liquid and a gas from each other in the sump, and the separator cover is at least partially concave-convex.

[0093] In some embodiments, the separator cover is a first separator cover that is at least partially concave-convex to reduce the deposition rate of excess coating material in the sump. The rate is at least reduced relative to a second separator cover that is at least partially plano-convex. The second separator cover is less concave-convex and more plano-convex than the first separator cover.

[0094] In certain embodiments, the sump includes a base coupled to each of the inner wall, the partition wall, and the outer wall. The sump also includes an inner wall that substantially surrounds the axis of rotation of the chuck. The sump also includes a partition wall that substantially surrounds the inner wall. The partition wall at least partially divides the interior of the sump into a liquid chamber and a gas chamber. The sump also includes an outer wall that substantially surrounds the partition wall.

[0095] In some embodiments, the partition cover is coupled to the inner wall but not to the partition wall. The partition cover substantially surrounds the rotation axis of the chuck. The partition cover may have a top surface and a bottom surface. The top surface is at least partially convex, and the bottom surface is at least partially concave. The partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber. The partition cover and the partition wall are adapted to keep the gas chamber substantially free of excess coating material during the coating operation.

[0096] Although the present embodiment has been disclosed with reference to certain embodiments, many modifications, variations and changes to the described embodiments are possible without departing from the field and scope of the present disclosure as defined in the appended claims. Accordingly, it is intended that the present embodiment is not limited to the described embodiments, and that it has the full scope defined by the language of the following claims and their equivalents.

Claims

1. A device for spin coating, the device comprising: a base coupled to each of the inner wall, the partition wall, and the outer wall; an inner wall substantially surrounding an axis of rotation of a chuck, the chuck being adapted to hold and rotate a wafer during a coating operation as coating material is dispensed onto the wafer; a partition wall substantially surrounding the inner wall, the partition wall at least partially dividing the interior of the device into a liquid chamber and a gas chamber; an outer wall substantially surrounding the dividing wall; as well as a partition cover coupled to the inner wall but not to the partition wall, the partition cover substantially surrounding the rotational axis of the chuck, the partition cover having a top surface and a bottom surface, the top surface being at least partially convex and the bottom surface being at least partially concave, the partition cover being adapted to divert excess coating material to flow through the partition wall and into the liquid chamber, wherein the partition cover and the partition wall are adapted to maintain the gas chamber substantially free of the excess coating material during the coating operation.

2. The device according to claim 1, wherein: The thickness measure of the spacer cover is reduced by increasing the concavity measure of the bottom surface of the spacer cover, thereby increasing the convexity measure of the spacer cover while reducing the plano-convexity measure of the spacer cover, wherein the convexity measure of the top surface of the spacer cover is reduced or remains unchanged.

3. The device according to claim 2, wherein: The reduced thickness measure of the separation cover enlarges the gas passage between the liquid chamber and the gas chamber, thereby reducing the velocity at which the gas is allowed to flow from the liquid chamber to the gas chamber when the gas is pumped through the device during the coating operation.

4. The device according to claim 3, wherein: The reduced rate at which the gas is allowed to flow also reduces the rate at which the excess coating material is allowed to flow in the liquid chamber, which in turn increases the rate of chemical interaction between the excess coating material and the solvent, which in turn reduces the deposition rate of the excess coating material within the device, thereby increasing an operational durability measure of the device, and wherein the operational durability measure is increased due to a reduced frequency of needing to clean or replace the device.

5. The device according to claim 4, wherein: The excess coating material comprises a polymer, the polymer comprises unexposed photoresist, and wherein the solvent comprises xylene.

6. The apparatus according to claim 1, further comprising: An outer cover includes a cover of the liquid chamber, the outer cover substantially surrounds the rotation axis of the chuck, and the outer cover is disposed above the liquid chamber and the partition wall.

7. The device according to claim 6, wherein: The partition cover is at least partially disposed over the liquid chamber, wherein the outer cover is at least partially disposed over the gas chamber, and wherein the outer cover is at least partially disposed over the partition cover.

8. The device according to claim 6, wherein: The base defines a liquid outlet for the liquid chamber and further defines a gas outlet for the gas chamber, wherein the outer cover defines an inlet including a liquid inlet or a gas inlet; wherein the gas outlet is operably connected to a pump adapted to cause air to be drawn into the device via the inlet and out of the device via the gas outlet, the air comprising clean room air, wherein the air is drawn into an exhaust system; wherein each of the plurality of coating materials and the solvent therefor are at least substantially discharged from the device via the liquid outlet.

9. The device according to claim 1, wherein: The spin coating device includes a water collection tank, which constitutes a component of the spin coater.

10. The apparatus according to claim 1, further comprising: a motor adapted to rotate the chuck at a specified rotational speed during said coating operation; as well as A dispenser adapted to dispense the coating material onto the wafer during the coating operation is disposed above the chuck.

11. The device according to claim 1, wherein: The coating operation is part of a process to form a plurality of semiconductor devices on the wafer, the plurality of semiconductor devices including thyristors or diodes including transient-voltage-suppression (TVS) diodes.

12. A spin coater comprising: a chuck adapted to hold and rotate the wafer during a coating operation as coating material is dispensed onto the wafer; a motor adapted to rotate the chuck at a specified rotational speed during the coating operation; as well as a dispenser adapted to dispense the coating material onto the wafer during the coating operation, the dispenser being disposed above the chuck; A sump has an outer cover and includes a separator cover adapted to separate liquid and gas in the sump, the separator cover being at least partially concave-convex.

13. The spin coater according to claim 12, wherein: The separator cover includes a first separator cover, wherein the first separator cover, which is at least partially concave and convex, is intended to reduce the deposition rate of excess coating material in the collection pool at least relative to a second separator cover, which is at least partially flat and convex, wherein the second separator cover is less concave and more flat than the first separator cover.

14. The spin coater according to claim 12, wherein: The water collection tank comprises: a base coupled to each of the inner wall, the partition wall, and the outer wall; an inner wall substantially surrounding the axis of rotation of the chuck; a partition wall substantially surrounding the inner wall, the partition wall at least partially dividing the interior of the sump into a liquid chamber and a gas chamber; and An outer wall substantially surrounds the partition wall.

15. The spin coater according to claim 14, wherein: The partition cover is coupled to the inner wall but not to the partition wall, the partition cover substantially surrounds the rotation axis of the chuck, and the partition cover has a top surface and a bottom surface, the top surface is at least partially convex and the bottom surface is at least partially concave.

16. The spin coater according to claim 15, wherein: The partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber, and wherein the partition cover and the partition wall are adapted to maintain the gas chamber substantially free of the excess coating material during the coating operation.

17. A spin coating method, the method comprising: providing a wafer in which a plurality of semiconductor devices are fabricated, the wafer comprising an isolation structure that laterally isolates the semiconductor devices from each other in the wafer; as well as One or more photolithography operations are performed on the wafer, the one or more photolithography operations including applying a coating material to the wafer using a spin coater, the spin coater including a water collection pool having an outer cover and including a separator cover, the separator cover being suitable for separating liquid and gas in the water collection pool, the separator cover being at least partially concave-convex.

18. The method according to claim 17, wherein: The separator cover includes a first separator cover, wherein the first separator cover, which is at least partially concave and convex, is intended to reduce the deposition rate of excess coating material in the collection pool at least relative to a second separator cover, which is at least partially flat and convex, wherein the second separator cover is less concave and more flat than the first separator cover.

19. The method according to claim 17, wherein: The water collection tank comprises: a base coupled to each of the inner wall, the partition wall, and the outer wall; an inner wall substantially surrounding the axis of rotation of the chuck; a partition wall substantially surrounding the inner wall, the partition wall at least partially dividing the interior of the sump into a liquid chamber and a gas chamber; and An outer wall substantially surrounds the partition wall.

20. The method according to claim 19, wherein: The partition cover is coupled to the inner wall but not to the partition wall, the partition cover substantially surrounds the rotation axis of the chuck, the partition cover has a top surface and a bottom surface, the top surface is at least partially convex, and the bottom surface is at least partially concave; wherein the partition cover is adapted to divert excess coating material to flow through the partition wall and into the liquid chamber, and wherein the partition cover and the partition wall are adapted to maintain the gas chamber substantially free of the excess coating material during a coating operation.

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