JP2008283150A - Semiconductor device and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device capable of reducing manufacturing cost and a size, and a method of manufacturing the same. <P>SOLUTION: The semiconductor device comprises a semiconductor chip in which a pad is formed on the surface of a semiconductor substrate and a beam structure exposed to the pad formation surface side of the semiconductor substrate is formed, and a protective cap which is formed of a resin sheet and protects a mobile structure so that it can move while being exposed to the pad in a state of being adhered and fixed on the pad formation surface of the semiconductor substrate. Then, the protective cap has a tapered part including a tapered side surface that connects the adhesion surface adhered with the pad formation surface of the semiconductor substrate and the backside of the adhesion surface, and the length X of the tapered part along the direction in which the pad and the structure are arranged in parallel with each other on the pad formation surface of the semiconductor substrate is made shorter than the length Y along the direction of the thickness of the semiconductor substrate, and the position of a vertex most distant from the structure in the parallel installation direction is a position between the backside of the adhesion surface and the adhesion surface in the direction of the thickness of the semiconductor substrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device having a structure formed of a semiconductor and a method of manufacturing the semiconductor device in which the structure is covered with a protective cap.

  Conventionally, a pad as an external connection terminal is formed on the surface of a semiconductor substrate, such as a semiconductor dynamic quantity sensor such as an acceleration sensor, an angular velocity sensor, or a pressure sensor, or an electrostatic actuator, and exposed to the pad forming surface side of a part of the semiconductor substrate. A semiconductor device in which at least a movable structure is formed as a structure is known.

In such a semiconductor device, in order to protect the movable structure, the movable structure is covered with a protective cap. For example, in Patent Document 1, by forming a protective cap using a resin sheet having heat resistance, wire bonding can be performed while leaving the protective cap while suppressing intrusion of grinding water during dicing.
JP 2000-31349 A

  In order to manufacture a semiconductor device having a protective cap made of a resin sheet at a low cost, the present inventor studied isotropic etching of the resin sheet in forming the protective cap. At that time, the resin sheet bonded to the support substrate is isotropically etched to form a recess corresponding to the movable structure and an exposed portion which is a through hole for exposing the pad, and the pad and the movable structure. A resin sheet was bonded to the semiconductor wafer on which the body was formed and diced into chips.

  A protective cap formed by isotropic etching has a taper including a tapered side surface that connects an adhesive surface with a pad forming surface of a semiconductor substrate and a back surface of the adhesive surface between at least the pad and the movable structure. It will have a part. The tapered portion is formed by forming an exposed portion, and includes a length Y (thickness of the resin sheet) along the thickness direction of the semiconductor substrate, and a pad and a structure on the pad forming surface of the semiconductor substrate. It is substantially equal to the length X along the side-by-side direction. Further, in the juxtaposing direction of the pad and the structure, the position of the apex portion farthest from the structure is substantially the same position as the back surface of the bonding surface in the thickness direction of the semiconductor substrate.

  As described above, if the protective cap has a tapered portion, the taper portion may become an obstacle when electrically connecting the wire and the pad, or the wire may contact the tapered portion and connection reliability may be reduced. Preferably, the pad is formed at a position separated from the movable portion with respect to the movable portion (a position not interfering with the tapered portion). However, considering the miniaturization of the semiconductor device, it is preferable to arrange the pad as close to the movable structure as possible. However, in the case of the above-described configuration, for example, when the thickness (length Y) of the resin sheet is 100 μm, the length X is almost 100 μm, and it is difficult to reduce the size of the semiconductor device. It is.

  In view of the above problems, an object of the present invention is to provide a semiconductor device and a method for manufacturing the same that can reduce the manufacturing cost and reduce the size.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a pad as an external connection terminal is formed on a surface of a semiconductor substrate, and a movable structure as a structure exposed on the pad forming surface side in a part of the semiconductor substrate. A semiconductor comprising: a semiconductor chip having at least a body; and a protective cap that is made of a resin sheet and that movably protects the movable structure while exposing the pad in a state of being adhesively fixed to the pad forming surface of the semiconductor substrate Device. The protective cap is formed by isotropic etching of the resin sheet between at least the pad and the structure, and has a tapered shape that connects the bonding surface with the pad forming surface of the semiconductor substrate and the back surface of the bonding surface. The length X along the direction in which the pads and the structure are arranged on the pad forming surface of the semiconductor substrate is longer than the length Y along the thickness direction of the semiconductor substrate. The position of the apex portion that is shortened and is most distant from the structure in the juxtaposed direction is a position between the back surface of the bonding surface and the bonding surface in the thickness direction of the semiconductor substrate.

  As described above, according to the present invention, when the protective cap is formed by isotropic etching of the resin sheet, a semiconductor device manufacturing method (multi-stage isotropic etching) described later is applied. The taper portion formed between at least the pad and the structure of the protective cap is small. Specifically, the length X is shorter than the length Y. Further, the position of the apex portion that is farthest from the structure in the juxtaposed direction is a position between the back surface of the bonding surface and the bonding surface in the thickness direction of the semiconductor substrate. With such a configuration, the manufacturing cost can be reduced compared to anisotropic etching such as reactive ion etching, and the pad can be brought close to the movable structure while having a tapered portion. Can be downsized.

  In addition, as a protective cap that movably protects the movable structure, for example, as described in claim 2, the movable structure may be provided on a portion that is opposed to the pad forming surface of the semiconductor chip and surrounded by the adhesive surface. A protective cap in which a recess is formed so as to cover the body can be employed. With such a configuration, even when the movable structure protrudes from the pad forming surface or is flush with the pad forming surface, the movable structure can be movably protected by the protective cap.

  In the invention according to claim 1 or 2, as described in claim 3, the resin sheet is etched to form a protective cap so as to cover the movable structure on the back surface of the adhesive surface of the protective cap. It is also possible to employ a configuration in which a mask member serving as a mask is arranged. In addition, the mask member may be removed after etching, and the mask member may not be disposed on the back surface of the adhesive surface of the protective cap.

  For example, as a material of the mask member, a metal material can be adopted as described in claim 4. In this case, as described in claim 5, the mask member is configured to be fixed at the GND potential, so that the mask member has a function of electromagnetic shielding, and the characteristic fluctuation due to the charging of the protective cap during the operation of the semiconductor device. Can also be suppressed.

  Next, invention of Claims 6-11 is related with the manufacturing method which forms the semiconductor device mentioned above. According to a seventh aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: preparing a semiconductor wafer having a plurality of pads as external connection terminals formed on the surface and at least a plurality of movable structures formed as structures exposed on the pad forming surface side. A wafer preparation step, and a sheet preparation step in which a resin sheet for protecting the movable structure is bonded to one surface of the support substrate on which a plurality of mask members corresponding to the movable structure are fixed via the mask member; The resin sheet supported by the support substrate is isotropically etched from the back side of the surface facing the support substrate to form a recess for movably covering the movable structure and penetrate the resin sheet. A first etching step for forming an exposed portion for exposing the pad, and after the first etching step, a resin sheet fixed to the support substrate is formed on the semiconductor wafer pad. Bonding process for removing the support substrate and bonding, and a dicing process for dicing the semiconductor wafer bonded with the resin sheet into chips, and after the bonding process, using the mask member as a mask, the resin sheet isotropic And a second etching step for performing etching.

  When the first etching step is completed, the through wall surface of the exposed portion becomes the tapered portion shown in claim 1, and the tapered portion is also formed between the pad and the movable structure. In the taper portion, the length Y along the thickness direction of the semiconductor substrate is substantially equal to the length X along the direction in which the pads and the structures are arranged on the pad forming surface of the semiconductor substrate. Further, in the juxtaposing direction of the pad and the structure, the position of the apex portion farthest from the structure is substantially the same position as the back surface of the bonding surface in the thickness direction of the semiconductor substrate. Furthermore, in the present invention, the resin sheet that is isotropically etched in the first etching step is isotropically etched again in the second etching step using the mask member as a mask. Therefore, the taper portion of the protective cap can be made smaller (the length X is shorter than the length Y) compared to the case of only the first etching. Note that, by the second etching step, the position of the apex portion becomes a position between the back surface of the bonding surface and the bonding surface in the thickness direction of the semiconductor substrate. Thus, according to the present invention, since the protective cap is formed only by isotropic etching, the manufacturing cost can be reduced as compared with anisotropic etching such as reactive ion etching. Moreover, since the pad can be brought close to the movable structure while having the tapered portion, the size of the semiconductor device can be reduced.

  In addition, as described in claim 7, in the first etching step, the exposed portion may be formed so as to be separated into a plurality of resin sheets having concave portions. In this case, the exposed portion has an annular shape surrounding the recess, and the tapered portion also has an annular shape. In addition, it is good also as an exposed part by opening so that only the site | part corresponding to a pad may be exposed.

  Next, the invention according to claim 8 is a wafer for preparing a semiconductor wafer in which a plurality of pads as external connection terminals are formed on the surface and at least a plurality of movable structures are formed as structures exposed on the pad forming surface side. The isotropic etching is applied to the preparation step and the resin sheet to form a recess for movably covering the movable structure, and an exposed portion for exposing the pad through the resin sheet. A first etching step, a bonding step of bonding the resin sheet to the pad forming surface of the semiconductor wafer after the first etching step, a dicing step of dicing the semiconductor wafer to which the resin sheet is bonded to form a chip, and bonding After the alignment process, a mask member is bonded to the back surface of the resin sheet facing the pad forming surface so as to cover the movable structure. And click fixing step, after the mask fixing step, a mask member as a mask, and having a second etching step of isotropically etching a resin sheet.

  The difference between the invention described in claim 8 and the invention described in claim 6 is that the mask member and the resin sheet are integrated in the sheet preparation step, or the resin sheet and the mask member are integrated after the bonding step. That is the difference. The other points are the same and the operational effects are also the same, so the description thereof is omitted.

  In addition, as described in claim 9, before the first etching step, the first etching step includes a sheet preparation step of bonding a resin sheet for protecting the movable structure on one surface of the support substrate. The resin sheet fixed to the support substrate is subjected to isotropic etching from the back side facing the support substrate to form a recess for movably covering the movable structure and penetrate the resin sheet. The exposed portion is formed so as to be separated into a plurality of resin sheets having recesses while exposing the pad, and in the bonding step, the resin sheet fixed to the support substrate is bonded to the pad forming surface of the semiconductor wafer. The support substrate may be removed. In this case, the exposed portion has an annular shape surrounding the recess, and the tapered portion also has an annular shape. In addition, it is good also as an exposed part by opening so that only the site | part corresponding to a pad may be exposed.

  In the invention according to any one of claims 6 to 9, as described in claim 10, the mask member may be removed in the removing step after the second etching step. According to this, a semiconductor device without a mask member can be formed.

  In the invention according to any one of claims 6 to 10, as described in claim 11, the resin sheet may be dry-etched in the second etching step. Note that dry etching is plasma etching performed by radicals generated by plasma, and includes ashing by plasma. In addition, wet etching can be employed. However, as described in claim 12, in the wafer preparation process, a movable electrode as a movable structure and a fixed electrode as a fixed structure disposed opposite to the movable electrode are formed as a structure, and the pad The movable electrode pad connected to the movable electrode via the wiring and the fixed electrode pad connected to the fixed electrode via the wiring are formed, and the movable electrode, the movable electrode pad, the fixed electrode, and the fixed electrode are formed. In a configuration in which a semiconductor wafer is isolated from each other by a trench provided in a semiconductor substrate, and a recess is formed in a resin sheet so as to cover the movable electrode and the fixed electrode in the first etching step. It is preferable to employ dry etching. According to this, there is no possibility that the etchant enters the structure side protected by the protective cap through the trench also existing around the pad as in wet etching.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of the semiconductor device according to the first embodiment of the present invention. FIG. 2 is a plan view of FIG. 1 viewed from the mask member side.

  As shown in FIGS. 1 and 2, the semiconductor device 100 includes, as main parts, a semiconductor chip 110 having at least a movable structure as a structure, and a protective cap 120 that movably protects the movable structure. Have.

  The semiconductor chip 110 has a pad 112 as an external connection terminal formed on the surface of a semiconductor substrate 111 and a movable structure at least as a structure 114 exposed on the pad forming surface side on a part of the semiconductor substrate 111. is there. In this embodiment, the semiconductor chip 110 has the same configuration as that described in Japanese Patent Application Laid-Open No. 9-211022 and Japanese Patent Application Laid-Open No. 2006-153482 by the applicant. Although a detailed description is omitted, a trench 113 is formed in a semiconductor substrate 111 made of single crystal silicon, thereby forming a beam structure as a movable structure that is displaced by acceleration as a part of the structure 114. Has been. Further, a fixed electrode having a beam structure is configured to face a movable electrode provided in the beam structure. That is, in this embodiment, the beam structure as a movable structure and the fixed electrode of the beam structure are the structures 114. Further, the pad 112 is electrically connected to the movable electrode and the fixed electrode via the wiring portion 115, and a trench 116 is also formed around the pad 112 and the wiring portion 115. Then, the trench 113 around the structure body 114 protected by the protective cap 120 and the trench 116 around the pad 112 electrically connected to the structure body 114 through the wiring portion 115 are communicated with each other, so that the movable electrode and the movable electrode are movable. The electrode pad 112 and the fixed electrode and the fixed electrode pad 112 are insulated and separated from each other. Thus, the semiconductor chip 110 is configured to detect acceleration based on a change in the facing distance between the movable electrode and the fixed electrode. In FIG. 1, the movable electrode and the fixed electrode are illustrated in the structure body 114.

  The protective cap 120 is formed by processing a resin sheet, and protects the movable structure movably while exposing the pad 112 in a state of being bonded and fixed to the pad forming surface of the semiconductor substrate 111. The protective cap 120 is bonded and fixed on the semiconductor chip 110 with an adhesive 130. As the resin sheet and the adhesive 130 constituting the protective cap 120, in the manufacturing process, a process after the process of fixing the protective cap 120 to the semiconductor chip 110 (for example, a process of connecting a wire to the pad 112 or a resin mold). That has higher heat resistance than the heat treatment temperature (for example, 150 ° C. to 180 ° C.) in the step of performing the step). Specifically, a polyimide resin having a heat resistance of about 400 ° C. can be used as a constituent material of the resin sheet, and a silicon-based adhesive having a heat resistance of about 230 ° C. can be used as the adhesive 130.

  The protective cap 120 is formed with a recess 121 (for example, a depth of about 30 μm) on the surface facing the semiconductor chip 110 (the pad forming surface of the semiconductor substrate 111) so as to cover the structure 114. The movable structure 114 can be displaced by acceleration as a mechanical quantity. Further, of the pad forming surface of the semiconductor substrate 111, an annular peripheral region including the pad 112 is exposed to the outside from the protective cap 120, and the pad 112 is formed by the protective cap 120 as shown in FIGS. It is formed in a position that is not hidden. Of the surface of the protective cap 120 facing the pad forming surface of the semiconductor substrate 111, a portion between the peripheral region and the recess 121 serves as an adhesive surface 123 with the adhesive 130 so as to surround the structure 114. Yes.

  Further, the protective cap 120 has a tapered portion 122 by tapering the side surface connecting the adhesive surface 123 and the back surface of the adhesive surface 123. The tapered portion 122 is defined by an end portion of the bonding surface 123 on the side away from the structure 114, an end portion of the bonding surface on the side away from the structure 114, and a tapered side surface. This is a part that is defined by the apex part 122a farthest from the structure 114 in the juxtaposition direction of the pad 112 and the structure 114. Then, the position of the apex portion 122a is a position between the back surface of the bonding surface 123 and the bonding surface 123 in the thickness direction of the semiconductor substrate 111, whereby the taper portion 122 is bonded to the bonding surface 123. With respect to the back surface of the surface 123, the vertex portion 122 a is convex in a direction away from the structure body 114. The tapered portion 122 has a length X (X2) along the direction in which the pads 112 and the structures 114 are juxtaposed, and a length Y along the thickness direction of the semiconductor substrate 111 (resin sheet thickness: for example, about 100 μm). ) Is shorter. The tapered portion 122 configured as described above is a main feature point in the semiconductor device 100 according to the present embodiment. The effect will be described later. Note that the length X is the juxtaposition of the pad 112 and the structure 114 in the end of the bonding surface 123 on the side away from the structure 114 and the end on the back of the bonding surface from the structure 114. In the direction, it is the length from the side closer to the structure body 114 to the apex portion 122a.

  Further, a mask member 140 serving as a mask when the protective cap 120 is formed by etching the resin sheet is fixed to the back surface of the adhesive surface 123 of the protective cap 120 so as to cover the structure 114. As a constituent material of the mask member 140, any material can be used as long as it functions as a mask when the resin sheet is etched. Specifically, a metal material such as copper or glass can be employed.

  Next, a method for manufacturing the semiconductor device 100 shown in FIGS. 1 and 2 will be described with reference to FIGS. FIG. 3 is a schematic cross-sectional view showing a manufacturing process of a semiconductor device, showing a wafer preparation process. FIG. 4 is a plan view of FIG. 3 viewed from the pad forming surface side. FIG. 5 is a schematic cross-sectional view showing a manufacturing process of the semiconductor device, showing a sheet preparation process. FIG. 6 is a schematic cross-sectional view showing a manufacturing process of the semiconductor device, showing a first etching process. FIG. 7 is a plan view of FIG. 6 viewed from the resin sheet side. FIG. 8 is a schematic cross-sectional view showing a manufacturing process of a semiconductor device, showing a bonding process. FIG. 9 is a schematic cross-sectional view showing a manufacturing process of the semiconductor device, showing a second etching process.

  First, as shown in FIGS. 3 and 4, a wafer preparation step is performed. In this wafer preparation process, a semiconductor wafer to be a plurality of semiconductor chips 110 is prepared by dicing. For example, Al pads 112, trenches 113, structures 114, and the like are formed on the surface of the semiconductor substrate 111 as a silicon wafer in accordance with the position of each semiconductor chip 110 by a known semiconductor technology. In FIG. 4, for convenience, only the structure 114 is shown by a rectangular frame.

  Further, as shown in FIG. 5, a sheet preparation process is performed. In this sheet preparation process, for example, a surface of a support substrate 150 made of glass or the like is publicly known to be peelable between the mask member 140 and the support substrate 150 due to a decrease in adhesiveness due to heating in a bonding process described later. A film (in this embodiment, a metal film) made of the constituent material of the mask member 140 is formed through the thermal peeling layer (not shown). Then, this film is patterned to form a mask member 140 corresponding to the position of each semiconductor chip 110. After the mask member 140 is formed, a resin sheet 124 to be processed later to be the protective cap 120 is bonded to one surface of the support substrate 150 to which the plurality of mask members 140 are fixed. Thereby, the resin sheet 124 supported by the support substrate 150 through the mask member 140 is prepared. As the resin sheet 124, a sheet having heat resistance in a bonding process described later can be used. In the present embodiment, a sheet made of a polyimide resin having a thickness of about 100 μm is used.

  After the sheet preparation process, as shown in FIGS. 6 and 7, a first etching process for isotropically etching the resin sheet 124 is performed. This first etching process is a first stage when the protective cap 120 is formed by isotropic etching. First, isotropic etching is selectively performed on the resin sheet 124 supported by the support substrate 150 from the back side of the surface facing the support substrate 150 to form a recess 121 for movably covering the movable structure. To do. This isotropic etching may be either wet etching or dry etching. In this embodiment, a recess 121 having a depth of about 30 μm is formed on a resin sheet 124 having a thickness of about 100 μm by wet etching using a known alkaline solution. Next, isotropic etching is selectively performed on the resin sheet 124 from the back side of the surface facing the support substrate 150 to form an exposed portion 125 for exposing the pad 112 through the resin sheet 124. To do. This isotropic etching may be either wet etching or dry etching. In this embodiment, wet etching using a known alkaline solution is adopted, and the exposed portion 125 is formed in a ring shape surrounding each recess 121. Form. Therefore, the resin sheet 124 is separated into a plurality of protective caps 120. In other words, the exposed portion 125 is used as the pad 112 and also serves as a reference for dicing.

  When the first etching step is completed, the through wall surface of the exposed portion 125 penetrating the resin sheet 124 has a tapered shape as shown in FIG. That is, an annular taper portion 122 surrounding the recess is formed. In the taper portion 122, the relationship between the length X and the length Y described above is substantially equal. Further, as described above, in the juxtaposed direction of the pad 112 and the structure body 114, the position of the vertex portion 122a farthest from the structure body 114 is substantially the same position as the back surface of the adhesive surface 123 in the thickness direction of the semiconductor substrate. It has become.

  After the first etching process, a bonding process is performed as shown in FIG. In this bonding step, first, a heat-resistant adhesive 130 is applied to either the bonding portion of the semiconductor substrate 111 or the bonding surface of the resin sheet 124 (protective cap 120). Next, in a state where the resin sheet 124 (protective cap 120) fixed to the support substrate 150 and the pad forming surface of the semiconductor substrate 111 face each other so that the structure 114 fits in the recess 121 of the protective cap 120. Then, the support substrate 150 is heated while being pressurized (about 400 ° C. in this embodiment), and the resin sheet 124 (protective cap 120) is bonded to the pad forming surface of the semiconductor substrate 111. At this time, since the adhesiveness of the thermal peeling layer described above is lowered, the supporting substrate 150 can be removed by peeling between the mask member 140 and the supporting substrate 150. Thus, in this embodiment, the transfer method is adopted. FIG. 8 shows a state where the support substrate 150 is removed. Thus, the structures 114 formed on the semiconductor substrate 111 are protected by the protective cap 120, respectively.

  As shown in FIG. 8, the pad 112 is in a state where at least a part is hidden by the taper portion 122 of the protective cap 120 (a state where the pad 112 enters under the eaves of the taper portion 122) before the second etching step. It has become.

After the bonding step, a second etching step is performed as shown in FIG. This second etching process is a second stage when the protective cap 120 is formed by isotropic etching. In the second etching step, the resin sheet 124 (protective cap 120) is isotropically etched using the mask member 140 as a mask. This isotropic etching may be either wet etching or dry etching. However, as described above, the trench 113 around the structure body 114 protected by the protective cap 120 and the trench 116 around the pad 112 electrically connected to the structure body 114 through the wiring portion 115 are communicated with each other. In the configuration in which a part of the trench 116 is exposed to the outside of the protective cap 120, when the trench 116 is immersed in an etchant like wet etching, the etchant enters the protective cap 120 through the trench 116, and the movable structure. There is a risk of hindering displacement. Therefore, dry etching is preferable. Note that dry etching is plasma etching performed by radicals generated by plasma, and includes ashing by plasma. In this embodiment, O ₂ plasma ashing (for example, 1 μm / min) is employed as an example.

  Thereby, the tapered portion 122 of the protective cap 120 exposed from the mask member 140 is isotropically etched. The tapered portion 122 has a length X that is shorter than the length Y. The position of the apex portion 122 a is a position between the back surface of the bonding surface 123 and the bonding surface 123 in the thickness direction of the semiconductor substrate 111. Further, as shown in FIG. 9, the pad 112 is not hidden by the taper portion 122 of the protective cap 120 (a state where the pad 112 protrudes from under the eaves of the taper portion 122).

  Then, although not shown, a dicing process is performed in which the semiconductor substrate 111 to which the resin sheet 124 (protective cap 120) is bonded is diced into chips by using the pads 112 and the exposed portions 125 exposed by the exposed portions 125 as a reference. carry out. Thereby, the semiconductor device 100 shown in FIGS. 1 and 2 can be formed.

  Next, functions and effects of the semiconductor device 100 and the manufacturing method thereof according to the present embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view for explaining the effect. In FIG. 10, the taper portion 122 is indicated by a solid line after the second etching step and by a broken line before the second etching step (after the first etching step). Further, the pad 117 when the second etching step is not performed is indicated by a one-dot chain line.

  As described above, the taper portion 122 formed by isotropic etching in the first etching step has a length X (X1) along the direction in which the pads 112 and the structures 114 are juxtaposed, as indicated by broken lines in FIG. ) Becomes substantially equal to the length Y (thickness of about 100 μm) along the thickness direction of the semiconductor substrate 111. Further, the position of the apex portion 122 a is substantially the same position as the back surface of the bonding surface 123 in the thickness direction of the semiconductor substrate 111. Therefore, considering the ease of connecting the wire to the pad 112 and the connection reliability of the wire, when the protective cap 120 is formed by performing only the first etching step, the position of the pad 117 is changed to the position of the bonding surface 123. The position must be at least 100 μm away from the edge.

  On the other hand, according to the manufacturing method shown in the present embodiment, the length X (X2) of the tapered portion 122 can be made shorter than the length Y. Further, the position of the apex portion 122 a can be a position between the back surface of the bonding surface 123 and the bonding surface 123 in the thickness direction of the semiconductor substrate 111. Therefore, the position of the pad 112 can be closer to the structure body 114 than the position of the pad 117.

  As described above, according to the manufacturing method of the semiconductor device 100 and the semiconductor device 100 formed by the semiconductor device 100 according to this embodiment, the protective cap 120 has the tapered portion 122 (the configuration in which the protective cap 120 is formed by isotropic etching). However, since the pad 112 can be brought close to the structure body 114, the size of the semiconductor device 100 can be reduced.

  Further, since the protective cap 120 is formed only by isotropic etching, the apparatus is simpler than anisotropic etching such as reactive ion etching, and the manufacturing cost can be reduced.

  In the present embodiment, an example in which the dicing process is performed after the second etching process is shown. However, the dicing process may be performed after the bonding process, and the second etching process may be performed after the dicing process.

(Second Embodiment)
Next, 2nd Embodiment of this invention is described based on FIGS. FIG. 11 is a schematic cross-sectional view showing a manufacturing process of the semiconductor device according to the second embodiment, showing a sheet preparation process. FIG. 12 is a schematic cross-sectional view showing a manufacturing process of a semiconductor device, showing a bonding process. FIG. 13 is a schematic cross-sectional view showing a manufacturing process of a semiconductor device, showing a mask fixing process.

  Since the semiconductor device manufacturing method according to the second embodiment is often in common with that according to the first embodiment, a detailed description of the common parts will be omitted, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, the example in which the mask member 140 is fixed to the support substrate 150 together with the resin sheet 124 in the sheet preparation process has been described. On the other hand, in the present embodiment, the mask member 140 is not attached to the back surface of the adhesive surface 123 of the protective cap 120 (resin sheet 124) after the bonding process but before the second etching process, not the sheet preparation process. It is characterized by a fixed point. Other points are the same as in the first embodiment.

  Specifically, in the sheet preparation step shown in FIG. 11, after preparing the resin sheet 124 supported by the support substrate 150 without using the mask member 140 and performing the first etching step, as shown in FIG. The resin sheet 124 (protective cap 120) is bonded to the semiconductor substrate 111. In this case, the above-described thermal release layer (not shown) is interposed between the support substrate 150 and the resin sheet 124, and the support substrate 150 is peeled off and removed from the resin sheet 124 at the time of bonding. After the bonding, as shown in FIG. 13, the mask member 140 is bonded to the back surface of the adhesive surface 123 of each protective cap 120. At this time, if a plurality of mask members 140 are provided on a support substrate (not shown), the mask members 140 can be bonded together. Then, after the mask member 140 is fixed, the second etching process is performed before the dicing process or after the dicing process.

  Thus, the semiconductor device 100 shown in the first embodiment can also be formed by the method for manufacturing the semiconductor device 100 according to the present embodiment. Therefore, the size of the semiconductor device 100 can be reduced, and the manufacturing cost can be reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 14 is a cross-sectional view illustrating a schematic configuration of the semiconductor device according to the third embodiment.

  Since the semiconductor device and the manufacturing method thereof according to the third embodiment are often in common with those according to the first embodiment, the detailed description of the common parts will be omitted below, and different parts will be mainly described. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, an example in which the potential of the mask member 140 is not particularly fixed is shown. As shown in FIG. 14, the present embodiment is characterized in that a mask member 140 made of a metal material such as copper is fixed at a GND potential. The other points are the same as in the first embodiment.

  As described above, according to the semiconductor device 100 according to the present embodiment, the mask member 140 can have an electromagnetic shielding function. Therefore, for example, even if the protective cap 120 is charged during the operation of the semiconductor device 100, it is possible to suppress the characteristic fluctuation caused by the charging.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a cross-sectional view illustrating a schematic configuration of the semiconductor device according to the fourth embodiment.

Since the semiconductor device and the manufacturing method thereof according to the fourth embodiment are often in common with those according to the first embodiment, the detailed description of the common parts will be omitted below, and different parts will be mainly described. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, an example in which the semiconductor device 100 includes the mask member 140 has been described. On the other hand, the present embodiment is characterized in that the mask member 140 is removed and the semiconductor device 100 does not have the mask member 140, as shown in FIG. The semiconductor device 100 having such a configuration can be formed by removing the mask member 140 in the removing step after the second etching step. When removing the mask member 140, it is not preferable to affect the pad 112, the wiring portion 115, and the like on the semiconductor substrate 111 side. Accordingly, as a constituent material of the mask member 140, a material from which the mask member 140 is selectively removed may be appropriately selected and adopted in consideration of an etching rate. For example, glass can be employed.

(Fifth embodiment)
Next, 5th Embodiment of this invention is described based on FIG.16 and FIG.17. FIG. 16 is a cross-sectional view illustrating a schematic configuration of the semiconductor device according to the fifth embodiment. FIG. 17 is a plan view of FIG. 16 viewed from the mask member side.

  Since the semiconductor device and the manufacturing method thereof according to the fifth embodiment are in common with those according to the first embodiment, detailed description of the common parts will be omitted below, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, in the pad forming surface of the semiconductor substrate 111, an example in which not only the pad 112 but also the pad 112 including the pad 112 and surrounding the structure 114 is exposed to the outside from the protective cap 120. Indicated. That is, the example in which the tapered portion 122 is formed on the outer peripheral side surface of the protective cap 120 so as to surround the structure body 114 is shown. On the other hand, in the present embodiment, as shown in FIGS. 16 and 17, the pad 112 or the periphery of the pad 112 on the pad forming surface of the semiconductor substrate 111 (in the present embodiment, that of the pad 112). Only the surrounding area is exposed to the outside from the protective cap 120. The other points are the same as in the first embodiment.

  The semiconductor device 100 having such a configuration can also be formed by the manufacturing method described above. Specifically, when the exposed portion 125 is formed in the first etching step, a through hole (contact hole) corresponding to the pad 112 is formed as the exposed portion 125. The through wall surface of the exposed portion 125, which is a through hole formed by isotropic etching, is tapered. Therefore, as shown in the first embodiment, the length X (X1) and the length Y are substantially equal, and the taper portion 122 where the apex portion 122a is substantially at the same position as the back surface of the bonding surface 123 is formed between the pad 112 and the structure. 114. In the second etching step, the portion of the protective cap (resin sheet 124) exposed from the mask member 140 is isotropically etched, so that the taper portion 122 has a length X (X1) shorter than the length Y. The apex portion 122a can be a structure between the back surface of the adhesive surface 123 and the adhesive surface 123. Therefore, the formation position of the pad 112 can be closer to the structure body 114 than the configuration in which the protective cap 120 is formed only by isotropic etching in the first step.

  As described above, according to the manufacturing method of the semiconductor device 100 and the semiconductor device 100 formed by the semiconductor device 100 according to this embodiment, the protective cap 120 has the tapered portion 122 (the configuration in which the protective cap 120 is formed by isotropic etching). However, since the pad 112 can be brought close to the structure body 114, the size of the semiconductor device 100 can be reduced. However, since the entire through wall surface of the exposed portion 125 as a through hole (contact hole) corresponding to the pad 112 is tapered to form the tapered portion 122, in the parallel arrangement direction of the pad 112 and the structure body 114, The tapered portion 122 is opposed to the pad 112. Therefore, as shown in the first embodiment, not only the pad 112 but also the structure including the pad 112 and the annular peripheral region surrounding the structure 114 is exposed to the outside from the protective cap 120 is more physique. It can be downsized.

  Also in this embodiment, since the protective cap 120 is formed only by isotropic etching, the apparatus is simpler than anisotropic etching such as reactive ion etching, and the manufacturing cost can be reduced.

  In the present embodiment, an example in which the exposed portion 125 is a through hole is shown in the configuration shown in the first embodiment. However, the configuration shown in the present embodiment can be configured by applying the manufacturing method shown in the second embodiment. Moreover, the exposed part 125 which is a through-hole can also be applied with respect to the structure shown in 3rd Embodiment and the structure shown in 4th Embodiment.

  As shown in the present embodiment, when the pad 112 or only the periphery of the pad 112 on the pad forming surface of the semiconductor substrate 111 is exposed to the outside from the protective cap 120, the first etching process ends. Later, the resin sheet 124 is integrated without being separated. Therefore, when the mask member 140 is pasted after the pasting step, the support substrate 150 can be omitted. That is, after the first etching process is performed on the resin sheet 124 that is not fixed to the support substrate 150, the bonding with the semiconductor substrate 111 is performed. Then, after the bonding process, the mask member 140 may be bonded and the second etching process may be performed. In this case, the dicing process may be performed at any timing before the mask member 140 is attached, after the mask member 140 is attached, before the second etching process, and after the second etching process.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example of an acceleration sensor is shown as the semiconductor device 100. However, the semiconductor device 100 is not limited to the above example. Any structure that includes at least a movable structure (a structure that needs to be protected by the protective cap 120) can be employed as the structure formed on the semiconductor substrate 111. For example, an angular velocity sensor or a pressure sensor can be employed.

  In the present embodiment, an example in which the concave portion 121 is formed on the surface of the protective cap 120 facing the semiconductor substrate 111 corresponding to the structure 114 is shown. However, when the adhesive 130 is thick or when the movable structure is positioned on the back side of the pad forming surface with respect to the pad forming surface, the protective cap 120 without the recess 121 can be employed.

In the present embodiment, an example is shown in which dry etching (O ₂ plasma ashing) is performed in the second etching step. However, wet etching may be performed in a configuration in which the etchant does not enter the protective cap 120 via a trench or the like formed on the semiconductor substrate 111 side.

It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 1st Embodiment. It is the top view which looked at FIG. 1 from the mask member side. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows a wafer preparation process. It is the top view which looked at FIG. 3 from the pad formation surface side. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows a sheet | seat preparation process. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows a 1st etching process. It is the top view which looked at FIG. 6 from the resin sheet side. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows the bonding process. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows a 2nd etching process. It is sectional drawing for demonstrating an effect. It is a schematic sectional drawing according to the process which shows the manufacturing process of the semiconductor device which concerns on 2nd Embodiment, and is a figure which shows a sheet | seat preparation process. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows the bonding process. It is a schematic sectional drawing according to the process which shows the manufacturing process of a semiconductor device, and is a figure which shows a mask fixing process. It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 3rd Embodiment. It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 5th Embodiment. It is the top view which looked at FIG. 16 from the mask member side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Semiconductor device 110 ... Semiconductor chip 111 ... Semiconductor substrate 112 ... Pad 114 ... Structure 120 ... Protection cap 121 ... Concave part 122 ... Tapered part 122a ... Vertex portion 123 ... adhesive surface 124 ... resin sheet 140 ... mask member

Claims (12)

A semiconductor chip in which a pad as an external connection terminal is formed on the surface of the semiconductor substrate, and a movable structure is formed at least as a structure exposed on the pad forming surface side in a part of the semiconductor substrate;
A semiconductor device comprising a protective cap made of a resin sheet and movably protecting the movable structure while exposing the pad in a state where the pad is exposed and fixed to the pad forming surface of the semiconductor substrate,
The protective cap is formed by isotropic etching of the resin sheet between at least the pad and the structure, and connects the adhesive surface with the pad forming surface of the semiconductor substrate and the back surface of the adhesive surface. A tapered portion including a tapered side surface,
The taper portion has a length X along the direction in which the pads and the structure are arranged on the pad forming surface of the semiconductor substrate shorter than a length Y along the thickness direction of the semiconductor substrate, and The position of the apex portion farthest from the structure in the juxtaposed direction is a position between the back surface of the adhesive surface and the adhesive surface in the thickness direction of the semiconductor substrate. .   The protective cap is formed with a recess so as to cover the movable structure at a portion facing the pad forming surface of the semiconductor chip and surrounded by the adhesive surface. Item 14. The semiconductor device according to Item 1.   A mask member serving as a mask when the resin sheet is etched to form the protective cap is disposed on the back surface of the adhesive surface of the protective cap so as to cover the movable structure. The semiconductor device according to claim 1 or 2.   The semiconductor device according to claim 3, wherein the mask member is made of a metal material.   The semiconductor device according to claim 4, wherein the mask member is fixed at a GND potential. A wafer preparation step of preparing a semiconductor wafer in which a plurality of pads as external connection terminals are formed on the surface and at least a plurality of movable structures are formed as structures exposed on the pad forming surface side;
A sheet preparation step of bonding a resin sheet for protecting the movable structure via the mask member on one surface of a support substrate to which a plurality of mask members are fixed corresponding to the movable structure;
The resin sheet supported by the support substrate is subjected to isotropic etching from the back side of the surface facing the support substrate to form a recess for movably covering the movable structure, and the resin A first etching step of forming an exposed portion for exposing the pad through the sheet;
A bonding step of bonding the resin sheet fixed to the support substrate to the pad forming surface of the semiconductor wafer and removing the support substrate after the first etching step;
A dicing step of dicing the semiconductor wafer on which the resin sheet is bonded;
A method for manufacturing a semiconductor device, comprising: a second etching step of isotropically etching the resin sheet using the mask member as a mask after the bonding step.   The method of manufacturing a semiconductor device according to claim 6, wherein in the first etching step, the exposed portion is formed so as to be separated into a plurality of resin sheets having the concave portion. A wafer preparation step of preparing a semiconductor wafer in which a plurality of pads as external connection terminals are formed on the surface and at least a plurality of movable structures are formed as structures exposed on the pad forming surface side;
The resin sheet is subjected to isotropic etching to form a recess for movably covering the movable structure, and an exposed portion for exposing the pad through the resin sheet. 1 etching process,
A bonding step of bonding a resin sheet to the pad forming surface of the semiconductor wafer after the first etching step;
A dicing step of dicing the semiconductor wafer on which the resin sheet is bonded;
After the bonding step, a mask fixing step of bonding a mask member to cover the movable structure on the back surface of the resin sheet facing the pad forming surface;
A method of manufacturing a semiconductor device, comprising: a second etching step of isotropically etching the resin sheet using the mask member as a mask after the mask fixing step. Before the first etching step, a sheet preparation step of bonding a resin sheet for protecting the movable structure on one surface of the support substrate,
In the first etching step, a recess for movably covering the movable structure by performing isotropic etching on the resin sheet fixed to the support substrate from the back side of the surface facing the support substrate. And forming the exposed portion so as to be separated into a plurality of resin sheets having the recesses while exposing the pad through the resin sheet,
9. The method of manufacturing a semiconductor device according to claim 8, wherein in the bonding step, the resin sheet fixed to the support substrate is bonded to the pad forming surface of the semiconductor wafer and the support substrate is removed.   The method for manufacturing a semiconductor device according to claim 6, further comprising a removal step of removing the mask member after the second etching step.   The method for manufacturing a semiconductor device according to claim 6, wherein in the second etching step, the resin sheet is dry-etched. In the wafer preparation step, as the structure, a movable electrode as the movable structure and a fixed electrode as a fixed structure opposed to the movable electrode are formed, and the movable electrode and the wiring are used as the pad. And a movable electrode pad connected via a wiring and a fixed electrode pad connected via a wiring to the movable electrode, the movable electrode pad, the movable electrode pad, the fixed electrode, and the fixed electrode pad. And preparing a semiconductor wafer insulated from each other by a trench provided in the semiconductor substrate,
The method of manufacturing a semiconductor device according to claim 11, wherein in the first etching step, a recess is formed in the resin sheet so as to cover the movable electrode and the fixed electrode.

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