JP4816022B2 - End point detection method in wet anisotropic etching and manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a wafer process in which a silicon wafer bonded to a transparent support substrate is immersed in an alkaline solution and wet anisotropic etching is performed to form a through trench (groove) or a trench (groove) leaving a thin residual silicon bottom film. In particular, the present invention relates to a process for detecting an end point of through trench etching, in which a wafer process is completed while the wafer state is maintained by the support substrate.

As shown in FIG. 3, a conventional method for detecting an end point in a wet etching process of a semiconductor wafer is a method and an apparatus for detecting an optimum etching end point by measuring the reflection intensity of an etching surface using a reflective optical sensor. (Light source 51, irradiation light 52, silicon wafer 53, reflected light 54, light receiving unit 55, spray nozzle 56, etching solution 57), and etching from a change in interference intensity of reflected light by changing the wavelength of laser light A method and apparatus for detecting the remaining film thickness and determining the optimum etching end point are known (Patent Documents 1 and 2).
In addition, when anisotropic etching using a strong alkaline solution is performed on a semiconductor wafer, a time management system that determines the end point using the fact that the etching depth is proportional to the time, or in the semiconductor wafer and the etching solution There are known a method of detecting an etching end point from a change in a current value flowing between the electrodes, and a method of detecting using a thickness sensor (Patent Document 3). However, the end point detection methods described in Patent Documents 1 to 3 are all single-wafer types that process semiconductor wafers one by one, and a plurality of semiconductor wafers cannot be processed at the same time. From this, it is difficult to say that it is preferable. Moreover, it is intended to etch a very shallow surface layer with respect to the semiconductor wafer, and does not correspond to deep etching that penetrates the semiconductor wafer.

In addition, in the manufacturing process of a chrome mask in which a predetermined metal thin film pattern is formed on a glass substrate, the end point of etching is detected by a change in the amount of light using light emitting and light receiving elements. The detection itself is a known technique (Patent Documents 4, 5, 6-conventional technique).
JP-A-1-232731 JP-A-8-325753 JP 2001-144068 A JP 61-121339 A JP-A 63-195337 JP-A-8-325753

On the other hand, if the trench etching with a depth penetrating in a lattice shape is formed by wet etching while leaving the semiconductor wafer as it is, the semiconductor chip becomes disjoint and the passivation process in the subsequent steps becomes complicated and difficult, and the conventional mesa semiconductor This is the same as the chip manufacturing process. Therefore, in order to perform etching that is deep enough to penetrate the semiconductor wafer (hereinafter, abbreviated as penetration etching), the semiconductor wafer is attached to a transparent support substrate that is resistant to etching. It is necessary to be able to maintain the wafer state.
When through etching is performed by a wet anisotropic etching process with the semiconductor wafer attached to the transparent support substrate in this way, the etching end point is set to an optimum etching depth to avoid insufficient etching or excessive etching. It is desirable to be able to make an appropriate and easy decision. Furthermore, there is little etching variation within the wafer surface and between wafers, and it is also desirable to reduce the cost by simultaneously etching a plurality of wafers to increase the processing efficiency and to make the process highly productive.

  In order to etch a semiconductor wafer into a silicon chip having a required bevel angle, it can be immersed in an alkaline solution and wet anisotropically etched to form a through trench (groove) or even if it is not penetrated. In the case of forming a trench having a thin silicon bottom film, in the conventional method of detecting the etching end point using reflected light, the silicon wafer penetrates, which should be the etching end point. When the thin silicon bottom film is left, the intensity of the reflected light becomes very weak and unstable, which indicates that there is a problem that the end point of etching cannot be detected with high accuracy. In addition, the conventional detection method can only deal with single-wafer etching in which the etching is performed one by one due to the configuration of the apparatus, so that a decrease in productivity during mass production can be avoided especially when the time required for etching is very long. There is also a problem of not. Therefore, for example, even when a batch etching method with high productivity that can process about 50 semiconductor wafers at a time is adopted, uniform etching with little variation can be performed and an etching end point can be detected easily and appropriately. Is strongly demanded.

  The present invention has been made in view of the problems as described above, and even when a trench (groove) penetrating the semiconductor wafer is formed by wet etching, the semiconductor chip is not separated from the semiconductor wafer, Moreover, an object of the present invention is to provide a method capable of simply detecting an appropriate etching end point, an etching apparatus using the end point detection method, and a method of manufacturing a semiconductor device having a process of trench etching a wafer using the etching end point detection method. To do.

According to the first aspect of the present invention, the light source component is provided on one surface side of at least one of the substrates to be etched of the substrate to be etched which is a semiconductor wafer bonded to a transparent support substrate. The light-receiving part is placed on the surface side and immersed in an etching tank, and while the trench is etched, the amount of light transmitted from the light source passing through the formed trench is measured by the light-receiving part and penetrates the trench. The object of the present invention is achieved by detecting a change in transmitted light amount that changes back and forth, and providing an end point detection method in wet anisotropic etching.
According to the second aspect of the present invention, the end point detection method in wet anisotropic etching according to the first aspect of the present invention is preferably the semiconductor wafer is a silicon wafer.
According to the present invention as set forth in claim 3, the end point detection method in wet anisotropic etching according to claim 1 or 2, wherein the trench etching is an etching using an alkaline solution. More preferably.

According to the present invention as set forth in claim 4, the end point detection method in wet anisotropic etching according to claim 3, wherein the alkaline solution is tetramethylammonium hydroxide. desirable.
According to the present invention as set forth in claim 5, a V-shaped opening is wider than the bottom by using a silicon wafer having a (100) surface and etching liquid using tetramethylammonium hydroxide solution. It is more desirable to use the end point detection method in wet anisotropic etching according to claim 4 in which the trench is formed.
According to the present invention as set forth in claim 6, the wet anisotropic process according to any one of claims 1 to 5, wherein the transparent support substrate is made of quartz glass or a transparent resin. It is preferable to use a method for detecting an end point in reactive etching.

According to the present invention as set forth in claim 7, the light source and the light receiving section are respectively arranged between an optical fiber for irradiation or a light receiving portion between measurement points arranged in the vicinity of either surface of the semiconductor wafer. It is more preferable to use the end point detection method in wet anisotropic etching according to any one of claims 1 to 6 connected by an optical fiber for use.
According to the present invention described in claim 8, it is possible to provide the end point detection method in wet anisotropic etching according to claim 7, wherein the optical fiber is a quartz optical fiber.
According to the present invention as set forth in claim 9, as an end point detection method in wet anisotropic etching according to claim 8, wherein the quartz optical fiber is coated with an alkali-resistant resin. Also good.

According to the present invention of claim 10, the wavelength of the light source is 400 nm to 2.0 μm, and the end point detection method in wet anisotropic etching according to claim 2, It is preferable to do.
According to the present invention of claim 11, when forming a V-shaped trench using a silicon wafer having a (100) surface, the light receiving portion is disposed on the opening side of the trench. The end point detection method in wet anisotropic etching according to claim 5, wherein a light source is arranged on the bottom side of the trench.
According to the present invention of claim 12, when a V-shaped trench is formed using a silicon wafer having a (100) surface, a light source is disposed on the trench opening side, The end point detection method in wet anisotropic etching according to claim 5, wherein the light receiving portion is arranged on the outer peripheral side of the transparent support substrate.

According to the thirteenth aspect of the present invention, when a V-shaped trench is formed using a silicon wafer having a (100) surface, a light receiving portion is disposed on the trench opening side. The end point detection method in wet anisotropic etching according to claim 5, wherein a light source is disposed on the outer peripheral edge side of the transparent support substrate.
According to the present invention as set forth in claim 14, the trench etching is performed while the optical fibers for irradiation and light reception and the silicon wafer are moved in parallel, up and down, left and right, and pendulum. It is more desirable to use the end point detection method in wet anisotropic etching according to claim 7 of the claims .

According to the present invention of claim 1 5, wherein the appended claims, the semiconductor functional region is formed on one surface of the semiconductor wafer, after forming an etching mask on the other side, bonding the transparent support substrate on the one side In the state, the end face detection method in wet anisotropic etching according to claim 1 of the above claims is used to etch the other side into a V-shape, and after removing the etching mask on the other side, the required semiconductor function The object of the present invention is achieved by a method for manufacturing a semiconductor device that performs region formation processing.

According to the present invention of claim 16, the semiconductor functional region formed on the one surface side is a MOS gate region, and the semiconductor functional region formed on the other surface side is an anode region. , it is preferable that the method of manufacturing a semiconductor device according to claim 1 5, wherein the appended claims the semiconductor device is a reverse blocking IGBT.

According to the present invention, even when a trench (groove) penetrating a semiconductor wafer is formed by wet etching, a semiconductor chip is not separated from the semiconductor wafer, and an appropriate etching end point can be easily detected, and its end point detection is performed. An etching apparatus using the method and a method for manufacturing a semiconductor device including a process of trench etching a wafer using the etching end point detection method can be provided.
According to the present invention, since an optical fiber or the like is used for transmission for light source or light reception, the configuration of the apparatus can be simplified, and it can cope with not only single wafer type but also batch type wet etching, and high production. Sex can be obtained.
Since the trench etching is performed in a state where the semiconductor wafer is bonded to the transparent support substrate, even a very thin wafer can be stably subjected to the trench etching process without causing a wafer crack or the like.

  FIG. 1 is a cross-sectional view showing through etching of a silicon wafer attached to a transparent support substrate according to the present invention, and FIG. 2 is a relationship diagram showing changes in transmitted light amount for detecting an end point of through etching according to the present invention. FIG. 4 is a schematic cross-sectional view of an end point detection apparatus in wet anisotropic etching according to the present invention, and FIG. 5 shows each tip of irradiation and light receiving optical fibers disposed opposite to the trench portion of the silicon wafer according to the present invention. FIG. 6 is a cross-sectional view showing the tip portions of the optical fibers for irradiation and light receiving disposed in the trench portion of the silicon wafer and the outer peripheral edge portion of the transparent support substrate according to the present invention, and FIG. FIG. 8 is a cross-sectional view showing light receiving, irradiating, and optical fiber tip portions disposed in the trench portion of the silicon wafer and the outer peripheral edge portion of the transparent support substrate, and FIG. 8 shows the semiconductor device according to the present invention. FIG. 9 is a plan view showing that a lattice-like trench of a semiconductor wafer according to the present invention is formed, and FIG. 10 is a view for receiving light sandwiching the semiconductor wafer according to the present invention. FIG. 11 is a perspective view showing that the optical fiber for irradiation and the optical fiber are moved up and down, left and right, FIG. 11 is a diagram showing the difference between the case where the optical fiber for measurement is fixed and the case where the optical fiber for measurement is moved, and FIG. The perspective view which shows arrangement | positioning of the optical fiber for a measurement at the time of detecting correctly the etching end point of the several semiconductor wafer concerning this invention, FIG. 13 is an etching end point correctly in one semiconductor wafer concerning this invention. It is a perspective view which shows arrangement | positioning of the optical fiber for a measurement at the time of detecting.

FIG. 8 shows a 1200 V reverse blocking IGBT (Insulated Gate Bipolar Transistor, hereinafter abbreviated as IGBT) as a semiconductor device according to the present invention, and a manufacturing method according to the present invention is applied to a silicon wafer or a quartz glass substrate for each step. It is sectional drawing shown with the to-be-etched substrate stuck. After forming the MOS gate structure 3 on one surface (front surface) 2 of the silicon wafer 1 (FIG. 8A), the other surface (back surface) 4 of the silicon wafer 1 is ground and etched to a wafer thickness of 180 μm ( FIG. 8B). A protective film such as a photoresist 6 or a silicon oxide film 7 is formed on the front surface 2 of the wafer 1 and the polished back surface 5 (FIG. 8D), and the wafer back surface 5 leaves a protective film 71 on the active portion 8. The wafer surface 2 is patterned so as to leave the protective film 61 in the scribe portion (FIG. 8E). The protective film 61 on the scribe portion of the wafer surface 2 serves as an etching stopper. The wafer surface 2 side is attached to a support substrate 9 made of quartz glass (FIG. 8 (f)), and the peripheral portion of the wafer is sealed 10 using a fluorine-based resin solution as necessary, so that the etching solution to the wafer surface 2 can be removed. Intrusion may be prevented (FIG. 8G). The wafer 1 is bonded to the support substrate 9 so that a thin wafer having a thickness of 180 μm in the 1200 V reverse blocking IGBT can be stably handled while maintaining the wafer state even during or after the alkali etching process of the next process. In order to prevent the wafer piece 12 or the chip piece 12 subjected to the separation pattern from falling off even if the lattice-shaped through V-shaped trench 11 is formed in the wafer surface. When silicon wafer 1 having a (100) crystal plane when etched for 10 hours at 80 ° C. using a 10% tetramethylammonium hydroxide solution as an etchant, the taper is 54.7 ° at the intersection of (100) plane and (111) plane. A V-shaped trench 11 having a corner can be formed (FIG. 8H). A plan view of the silicon wafer 1 in which the V-shaped trenches 11 are formed in a lattice shape is shown in FIG. In the wet anisotropic etching for forming the V-shaped trench 11, in order to detect the etching end point, the light receiving portion 16 is arranged on the opening side of the V-shaped trench 11 and the bottom of the V-shaped trench is formed. A light source 15 is arranged facing the quartz glass substrate side. By passing through the V-shaped trench 11, the light from the light source that increases rapidly can pass through the V-shaped trench and detect the transmitted light at the light receiving unit 16, thereby accurately detecting the etching end point of the penetrating V-shaped trench 11. it can. The protective film 71 on the wafer back surface 5 is removed (FIG. 8I), and boron is ion-implanted 13 at a dose of 1 × 10 ¹⁵ atoms / cm ² and an acceleration voltage of 100 keV (FIG. 8J). Boron ion-implanted by YAG laser irradiation on the ion-implanted surface is electrically activated to form the collector layer 14 (FIG. 8 (k)). At this time, boron ions are implanted not only in the collector layer but also in the V-shaped trench. Since the boron layer is also weakly doped on the side wall surface of the V-shaped trench, the electric field concentration on the surface of the trench 11 is relaxed, and the forward breakdown voltage and the reverse breakdown voltage of the IGBT are improved. Next, a protective film filling the V-shaped trench is formed using an oxide film or the like. A metal electrode (not shown) is formed on the surface of the collector layer 14 on the wafer back surface 5 side, and a chip is picked up to complete a 1200 V reverse blocking IGBT. In this way, in the reverse blocking IGBT manufacturing method, when forming the isolation layer (V-shaped trench in this embodiment) after forming the MOS gate structure on the surface 2 side of the silicon wafer, the isolation layer (V-shaped trench) In order to electrically activate the implanted dopant (boron), high-temperature annealing using a high-temperature furnace heats the entire silicon wafer, so the semiconductor characteristics of the IGBT fluctuate and cannot be used. A local thermal annealing technique that can heat only the very vicinity including the ion-implanted region to a desired temperature is preferable. When the taper angle of the isolation layer (V-shaped trench) described above is steep (for example, 80 °), laser irradiation becomes insufficient, and sufficient dopant activation for obtaining reverse blocking ability cannot be obtained. In order to sufficiently activate the dopant (boron) by irradiating the separation layer (V-shaped trench) with a laser in order to obtain the reverse blocking ability, wet anisotropic etching is performed with an alkaline solution as in this embodiment, It is desirable to form a V-shaped trench having a taper angle of 54.7 ° at the intersection angle between the (100) plane and the (111) plane by utilizing the difference in etching rate depending on the plane orientation. Since the etching time is long to form a V-shaped trench that penetrates the wafer by wet anisotropic etching, a batch-type etching method is desirable. According to the present invention, a light source that rapidly increases due to the penetration of the trench By detecting the transmitted light passing through the support substrate at the light receiving portion, the end point of the etching can be detected with high accuracy, so that high productivity can be obtained in the manufacturing process of the reverse blocking IGBT.

  FIGS. 1-2 shows Example 2 concerning the end point detection method in the wet anisotropic etching of this invention. First, as shown in FIG. 4 according to the end point detection apparatus in wet anisotropic etching of the present invention, an etching vessel 21 containing an alkaline etching solution 20 such as tetramethylammonium hydroxide solution is shown in FIG. A wafer carrier 24 on which a silicon wafer 23 bonded to a support substrate 22 made of quartz glass is set is immersed. A quartz optical fiber 26 connected to the light source 25 is inserted on one side of the silicon wafer 23, and a quartz optical fiber 28 connected to a light receiving portion (photodiode) 27 is inserted on the other side. As shown in FIG. 1, as the trench etching progresses with time, the trench 29 becomes deeper (FIGS. 1B and 1C), and the trench 29 penetrates (FIG. 1D). When the trench 29 penetrates, the amount of transmitted light from the light source 25 through the trench 29 increases abruptly as shown in (c) to (d) of FIG. FIG. 2 is a relationship diagram in which the horizontal axis represents the etching time and the vertical axis represents the transmitted light amount, and is shown in the display device that is calculated so that the transmitted light amount detected by the light receiving unit 27 can be visually observed by the end point detection device of FIG. FIG. In this way, by arranging the light source 25 in the trench opening on one side of the silicon wafer 23 in which the through trench 29 is formed and the light receiving unit 27 on the other side, the penetration through the trench 29 is completed and the abrupt passage through the trench 29 is abrupt. By detecting the increasing transmitted light amount at the light receiving portion, the end point of the through trench etching can be detected with high accuracy.

  As described in the first embodiment, the silicon wafer 23 is bonded to the support substrate 22 when the through trenches formed in a lattice shape are formed in the silicon wafer surface, and the chip pieces separated from the wafer by the through trenches. This is to prevent falling off. The reason why the silicon wafer is bonded to the support substrate is to prevent the wafer from cracking and to handle it stably in the wafer state when etching a thin wafer having a thickness of, for example, 100 μm.

  FIG. 5 shows Example 3 according to the end point detection method in wet anisotropic etching of the present invention. When the silicon wafer 23 having the (100) plane 30 as a surface is etched with an alkaline solution 20 (for example, tetramethylammonium hydroxide), there is a large difference in etching rate depending on the plane orientation of the silicon wafer 23. A V-shaped trench 29 having a taper angle of 54.7 ° at the intersection angle of the (111) plane can be formed. In the case of forming such a V-shaped trench 29, as shown in FIG. 5, the light-receiving-unit-side measuring component 31 is disposed on the opening side of the V-shaped trench 29, and the light source-side light irradiation component 32 is disposed on the bottom of the V-shaped trench. It is good to arrange. In this way, the loss of the amount of received light can be reduced, and the detection accuracy of the etching end point is improved.

  FIG. 6 shows Example 4 according to the end point detection method in wet anisotropic etching of the present invention. When the trench 29 penetrating the silicon wafer 23 bonded to the quartz glass support substrate 22 is formed, the light source side light irradiation component 32 is disposed on the opening side of the trench 29 and received on the outer peripheral edge side of the support substrate 22. The part-side measuring component 31 is arranged, and the light-receiving part-side measuring component 31 detects a change in the amount of transmitted light that suddenly increases due to the penetration of the trench 29, and the light scattered through the trench 29 toward the outer peripheral edge side of the support substrate 22. In this case, the position of the light receiving unit side measuring component 31 can be fixed to the outside between the wafers, and the influence of the light receiving optical fiber on the trench etching can be eliminated.

  FIG. 7 shows Example 5 according to the end point detection method in wet anisotropic etching of the present invention. When the trench 29 penetrating the silicon wafer 23 bonded to the support substrate 22 made of quartz glass is formed, the light receiving unit side measuring component 31 is disposed on the opening side of the trench 29 and the light source is disposed on the outer peripheral edge side of the support substrate 12. A light-receiving-unit-side measuring component in which the side-light-irradiating component 32 is arranged, irradiates light from the outer peripheral edge side of the support substrate 12, and transmits transmitted light that enters from the bottom of the trench 29 through the trench 29. Detect at 31. In this case, since the light irradiated from the outer peripheral edge side of the support substrate is delivered to all within the surface of the silicon wafer, the etching end point is located anywhere on the trench as long as the position of the light receiving side measurement component 31 is on the trench. There is an advantage that can be detected.

FIG. 10 shows Example 6 according to the end point detection method in wet anisotropic etching of the present invention. Two optical fibers for irradiation and reception coated with fluororesin are fixed to a support rod made of quartz glass, and optical fibers for irradiation and reception are sandwiched between the batch-type silicon wafers being etched. Between the opposite optical axes. During etching, the optical fiber bundle (probe) is moved up and down, left and right, and the pendulum is moved so that precise alignment between the optical fiber bundle and the trench opening is not required, and etching (trench penetration through the wafer) can be detected. It is. In addition, if the optical fiber bundle is fixed at a fixed position between the silicon wafers, etching unevenness may occur in the vicinity of the optical fiber and away from the optical fiber due to the three-dimensional obstacle of the optical fiber itself. However, there is an advantage that etching unevenness is eliminated by moving the pendulum up and down, left and right.

  FIG. 11 shows the relationship between the presence / absence of pendulum movement of the measurement optical fiber bundle (probe) and the amount of light transmitted through the through trench according to the present invention. When there is no pendulum movement, as shown in FIGS. 11 (a) and 11 (c), when the probe position and the position of the opening are exactly aligned (reference numeral 35 in FIG. 11 (c)), it is sufficient. The end point of etching can be detected by a clear change in the amount of light that is obtained, but if the probe and the opening are misaligned (reference numeral 36 in FIG. 11C), a sufficient change in the amount of light cannot be obtained and the end point is detected. Is difficult. Therefore, when there is no pendulum motion, it is important to accurately align the positional relationship between the probe and the trench before etching. On the other hand, when a pendulum motion is applied to the probe, as shown in FIGS. 11B and 11D, the amount of transmitted light can be easily changed without aligning the probe and the silicon wafer. There is an advantage that the etching end point can be clearly detected. The above-described pendulum movement can be executed by relatively moving either the probe or the silicon wafer or both of them, but a method in which the silicon wafer is fixed and the probe is moved by the pendulum is preferable.

  FIG. 12 shows Example 7 according to the end point detection method in wet anisotropic etching of the present invention. It is an example of endpoint detection in batch processing (collective processing of a plurality of wafers) using the present invention. In this case, the measurement optical fiber bundles (probes) 37, 38, and 39 are arranged at, for example, three locations of both ends and the center of a plurality of wafers to detect the end points. In this way, after confirming that through holes have been formed in all wafers from the left end to the right end of the plurality of wafers, the etching can be terminated.

FIG. 13 shows Example 8 according to the end point detection method in wet anisotropic etching of the present invention. Example 8 is an example of endpoint detection at several points in the surface of a single wafer. After confirming that the through hole has been formed in the same wafer surface, the etching can be terminated. In Examples 7 and 8, the application embodiments of the present invention may be appropriately used as appropriate.
FIG. 9 is a plan view showing a state in which through trenches (grooves) are formed by etching from one surface side in a lattice shape on a silicon wafer. Since this silicon wafer is bonded in advance to a quartz glass support substrate (not shown), it is prevented that the silicon wafer is separated into individual silicon chips after the through etching is finished. When two optical fiber bundles (probes) for irradiation and light reception are inserted into such a silicon wafer, the wafer is sandwiched between two opposing optical fibers, and etched to form a through trench. When detecting the change in the amount of transmitted light, if the optical axis between the two optical fiber tips of irradiation and reception cannot be aligned so as to exactly match the trench opening, Therefore, it may be difficult to accurately detect the etching end point. Even in such a case, according to the present invention, the amount of light transmitted from the through trench can be monitored while the optical fiber bundle for irradiation and reception is moved up and down, left and right, and pendulum in parallel with the silicon wafer. As a result, the optical axis between the optical fibers and the opening may coincide with each other instantaneously, but if the amount of light at the coincidence is monitored during etching, the optical fiber bundle and the trench opening are accurately aligned. Is not necessarily required, and the etching end point (wafer penetration through the trench) can be easily detected and determined.

Sectional drawing which shows the through etching of the silicon wafer affixed on the transparent support substrate, Relationship diagram showing the amount of transmitted light change for detecting the end point of through etching, Sectional drawing which shows the detection method of the etching end point using the conventional reflected light, Schematic sectional view of an end point detection apparatus in wet anisotropic etching according to the present invention, Sectional drawing which shows each front-end | tip part of the optical fiber for irradiation arrange | positioned at the trench part of the silicon wafer concerning this invention, and the outer periphery part of a transparent support substrate, Sectional drawing which shows each front-end | tip part of the optical fiber for irradiation arrange | positioned at the trench part of the silicon wafer concerning this invention, and the outer periphery part of a transparent support substrate, Sectional drawing which shows each front-end | tip part of the light-receiving, irradiation, and optical fiber arrange | positioned at the trench part of the silicon wafer concerning this invention, and the outer peripheral part of a transparent support substrate, Sectional drawing which shows the process step of the manufacturing method of the semiconductor device concerning this invention, The top view which shows that the lattice-like trench of the semiconductor wafer concerning this invention is formed, The perspective view which shows moving the optical fiber for light reception, irradiation, and an optical fiber which pinches | interposes the semiconductor wafer concerning this invention up and down, right and left, The figure which shows the difference of the change figure of the transmitted light quantity when the optical fiber for measurement is fixed and when moving, The perspective view which shows arrangement | positioning of the optical fiber for a measurement at the time of detecting correctly the etching end point of the several semiconductor wafer concerning this invention, It is a perspective view which shows arrangement | positioning of the optical fiber for a measurement at the time of detecting correctly an etching end point within one semiconductor wafer concerning this invention.

Explanation of symbols

1, 23 Silicon wafer 2, surface side 3, MOS gate region 4, back surface side 5, polished back surface side 6, photoresist 7, oxide film 8, active regions 9 and 22, support substrate 10, seals 11 and 29, V-shaped trench 12, ion implantation 13, collector layer 15, irradiation side component 16, light receiving side component 20, etching solution 21, etching tank 24, wafer carrier 25, light source 26, light source side optical fiber 27, light receiving unit 28, light receiving unit Side optical fiber 30, (100) surface 31, light receiving unit side measurement component 32, light source side irradiation component.

Claims (16)

A substrate to be etched consisting of a semiconductor wafer bonded to a transparent support substrate is immersed in an etching tank with a light source component on one side of the substrate to be etched and a light receiving part on the other side. Then, while the trench is being etched, the amount of light transmitted from the light source passing through the formed trench is measured by the light receiving unit, and the end point of the trench etching is detected by detecting the change in the amount of transmitted light that changes before and after the penetration of the trench. A method for detecting an end point in wet anisotropic etching. 2. The end point detection method in wet anisotropic etching according to claim 1, wherein the semiconductor wafer is a silicon wafer. 3. The end point detection method in wet anisotropic etching according to claim 1, wherein the trench etching is etching using an alkaline solution. The end point detection method in wet anisotropic etching according to claim 3, wherein the alkaline solution is tetramethylammonium hydroxide. 5. A wet-type trench according to claim 4, wherein a silicon wafer having a (100) surface is used and a V-shaped trench having an opening wider than the bottom is formed by an etching solution using a tetramethylammonium hydroxide solution. End point detection method in isotropic etching The end point detection method in wet anisotropic etching according to any one of claims 1 to 5, wherein the transparent support substrate is made of quartz glass or transparent resin. 2. The light source and the light receiving unit are connected to a measurement point arranged in the vicinity of one of the surfaces of the semiconductor wafer by an irradiation optical fiber or a light receiving optical fiber, respectively. The end point detection method in wet anisotropic etching as described in any one of Claim 6. The end point detection method in wet anisotropic etching according to claim 7, wherein the optical fiber is a quartz optical fiber. 9. The end point detection method in wet anisotropic etching according to claim 8, wherein the quartz optical fiber is coated with an alkali-resistant resin. The end point detection method in wet anisotropic etching according to claim 2, wherein the light source has a wavelength of 400 nm to 2.0 µm. When a V-shaped trench is formed using a silicon wafer having a (100) surface, a light receiving portion is disposed on the opening side of the trench and a light source is disposed on the bottom side of the trench. The end point detection method in wet anisotropic etching according to claim 5. When forming a V-shaped trench using a silicon wafer having a (100) surface, a light source is disposed on the trench opening side, and a light receiving unit is disposed on the outer peripheral side of the transparent support substrate. The end point detection method in wet anisotropic etching according to claim 5. When forming a V-shaped trench using a silicon wafer having a (100) surface, a light receiving portion is disposed on the trench opening side, and a light source is disposed on the outer peripheral side of the transparent support substrate. The end point detection method in wet anisotropic etching according to claim 5. 8. The wet anisotropic etching according to claim 7, wherein the trench etching is performed while causing the irradiation and light receiving optical fibers and the silicon wafer to move relatively parallel, up and down, left and right, and pendulum. End point detection method. 2. The end point detection in wet anisotropic etching according to claim 1, wherein a semiconductor functional region is formed on one side of the semiconductor wafer, an etching mask is formed on the other side, and a transparent support substrate is bonded to the one side. A method of manufacturing a semiconductor device, comprising: etching a second surface side in a V-shape by a method, and performing a required semiconductor functional region forming process after removing the etching mask on the second surface side. 2. The semiconductor functional region formed on the one surface side is a MOS gate region, the semiconductor functional region formed on the other surface side is an anode region, and the semiconductor device is a reverse blocking IGBT. 6. A method for producing a semiconductor device according to 5 .

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