JP2006237401A - Method for manufacturing semiconductor sensor chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor sensor chip allowing improvements in productivity in manufacturing the chip itself and its mounting further effectively. <P>SOLUTION: When a through-hole 27 and a through-hole 34 are formed by etching at the same time, etching is carried out from the reverse surface side of a silicon wafer 32 for the through-hole 27 and from the top surface side of the silicon wafer 32 for the through-hole 34. Consequently, the top surface side of the silicon wafer 32 is plated after the through-hole 27 and through-hole 34 are bored in the different surfaces of the silicon wafer 32. While the through-hole 27 is kept hollow as it is, only the through-hole 34 is filled with a conductor to form a through electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor sensor chip including a diaphragm formed on an upper surface of a semiconductor substrate.

  In recent years, with the progress of technology related to MEMS (Micro Electro Mechanical System), many fine semiconductor sensor chips having a movable diaphragm formed on a semiconductor substrate have been developed. MEMS is a semiconductor substrate in which mechanical parts (movable parts) and electric parts are formed by applying a semiconductor microfabrication technique. As the diaphragm type semiconductor sensor as described above, for example, an acoustic sensor, a pressure sensor, an acceleration sensor, and the like have been put into practical use.

  Conventionally, as a diaphragm type acoustic sensor, for example, a capacitance sensing type semiconductor microphone as shown in Patent Document 1 has been proposed. A capacitance-sensing semiconductor microphone includes a movable diaphragm electrode that vibrates in accordance with the propagation of sound pressure, and a fixed electrode that is fixed to a semiconductor substrate. The diaphragm electrode and the fixed electrode are disposed to face each other, and a capacitor is formed by both electrodes. When the diaphragm electrodes vibrate due to the propagation of sound pressure, the distance between the electrodes changes, and the capacitance of the capacitor formed by both electrodes changes. The capacitance-sensing semiconductor microphone is configured to output a detection signal based on a voltage change accompanying such a capacitance change.

  Incidentally, in the semiconductor substrate (semiconductor sensor chip) on which the diaphragm type semiconductor sensor as described above is formed, the diaphragm is separated from the semiconductor substrate in order to allow vibration / deformation of the diaphragm through propagation of vibration / pressure fluctuation. It is necessary to arrange in a state. Therefore, in many semiconductor sensor chips, in order to reduce air resistance, a through-hole penetrating from the surface on which the diaphragm is formed to the surface on the opposite side is formed at the position where the diaphragm is formed on the semiconductor substrate. ing.

  Usually, the semiconductor sensor chip as described above is used in a state of being accommodated in a package for protection. Conventionally, packaging of such a semiconductor sensor chip is performed in a manner as seen in, for example, Patent Document 2. That is, the semiconductor sensor chip is bonded to a printed wiring board together with an IC (Integrated Circuit) chip on which the integrated circuit for control is formed, and the upper surface of the bonded printed wiring board is covered with a cover. Thus, the packaging of the semiconductor sensor has been made. At this time, in the semiconductor sensor chip, for the purpose of exposing the upper surface of the diaphragm, the MEMS structure such as the diaphragm is usually formed on the surface of the semiconductor substrate opposite to the side bonded to the printed wiring board. For this reason, conventionally, the electrical connection between the IC chip or the printed wiring board in the package and the semiconductor sensor chip is basically performed by wire bonding.

In addition, as a conventional technique related to the present invention, the technique described in Patent Document 3 is publicly known.
JP-T 60-500841 JP-T-2004-537182 JP 2000-124217 A

  When wire bonding is performed, it is necessary to form bonding electrode pads on the upper surfaces of both the printed wiring board and the sensor chip. For this reason, the mounting area of the printed wiring board and the sensor chip is increased by the area of the electrode pads, which leads to an increase in the size of the semiconductor sensor package module.

  Further, in wire bonding, there is a possibility that a manufacturing defect may occur due to ultrasonic vibration generated when the wire is connected to the electrode pad for bonding. Since a general semiconductor device having no MEMS structure has a solid bulk structure with almost no gaps, thin wire portions, and thin wall portions, the resistance to such ultrasonic vibration is relatively high. . On the other hand, a semiconductor sensor including a movable part such as a diaphragm is often formed with a gap, a thin line portion, and a thin portion, and has a structure in which a manufacturing defect due to ultrasonic vibration is likely to occur. Especially in microphones that detect sound, the rigidity of the diaphragm cannot be increased so much in order to increase its sensitivity, so the influence of ultrasonic vibration is more pronounced than other diaphragm type semiconductor sensors such as pressure sensors and acceleration sensors. It has become a thing.

  Wire bonding also has a problem in terms of production cost. Generally, either gold or aluminum is used as the bonding electrode pad. In a normal semiconductor device having no MEMS structure, aluminum having a lower material cost is often used as its material. However, in a semiconductor sensor having a MEMS structure, it is necessary to remove the sacrificial layer with hydrofluoric acid to form the movable part, and the use of highly soluble aluminum with hydrofluoric acid is limited. Inevitably, production costs may increase.

  Therefore, there is a demand for electrical connection to the outside of the semiconductor sensor chip using a technique other than wire bonding. However, if electrical connection to the outside is possible by a method other than wire bonding, the structure of the semiconductor sensor chip itself may be complicated, and eventually there is a possibility that sufficient productivity cannot be improved.

  The present invention has been made in view of such a situation, and the problem to be solved is a semiconductor sensor chip that can further effectively improve the productivity of manufacturing the chip itself and mounting it. It is to provide a manufacturing method.

  According to the first aspect of the present invention, a diaphragm is formed on the upper surface of the semiconductor substrate, and a through-hole penetrating from the upper surface of the semiconductor substrate to the lower surface thereof is formed at the position where the diaphragm of the semiconductor substrate is formed. A method of manufacturing a semiconductor sensor chip, comprising: a step of forming a through hole penetrating an upper surface and a lower surface of the semiconductor substrate by etching simultaneously with the through hole; and a conductor in the formed through hole. And a step of forming a through electrode that is embedded and penetrates the semiconductor substrate.

  In the above manufacturing method, the through electrode penetrating the upper surface and the lower surface of the semiconductor substrate is formed on the semiconductor sensor chip. In such a semiconductor sensor chip, the diaphragm formed on the upper surface of the semiconductor substrate can be directly electrically connected to the lower surface of the semiconductor substrate via the through electrode. Therefore, problems associated with wire bonding, such as an increase in mounting area, generation of manufacturing defects due to ultrasonic vibration, and increase in production cost, can be solved.

When manufacturing a semiconductor sensor chip having the through electrode as described above, two types of holes penetrating the semiconductor substrate are formed: a through hole provided at a position where the diaphragm is formed and a through hole for the through electrode. There is a need. Such holes can be formed by etching the semiconductor substrate. However, if the through holes and the through holes are formed by separate etching, the number of manufacturing steps increases. In that respect, in the manufacturing method described above, since the through hole and the through hole are simultaneously formed by etching, an increase in man-hours can be suppressed. Therefore, according to the manufacturing method, it is possible to effectively improve the productivity related to the manufacture and mounting of the semiconductor sensor chip itself.

  By the way, in the semiconductor sensor chip having the through electrode as described above, it is necessary to embed a conductor in the through hole forming the through electrode. However, in a normal method, only the through hole is left with the through hole being hollow. It is difficult to selectively embed the conductor, and the conductor may be buried in the through hole simultaneously with the through hole. Such selective embedding of the conductor can be easily and accurately performed by using the manufacturing method according to claims 2 and 3.

  That is, in the invention described in claim 2, a diaphragm is formed on the upper surface of the semiconductor substrate, and a through-hole penetrating from the upper surface of the semiconductor substrate to its lower surface is formed at the position of the diaphragm of the semiconductor substrate. A method of manufacturing a semiconductor sensor chip, wherein a through hole penetrating an upper surface and a lower surface of the semiconductor substrate is formed by etching simultaneously with the through hole, and the through hole and the through hole are formed. Forming a conductive plating base film on the bottom surface of the semiconductor substrate, and including a through hole portion and a through hole portion on the bottom surface of the semiconductor substrate on which the plating base film is formed. A step of forming a plating resist layer so as to remove, and immersing the lower surface of the semiconductor substrate on which the plating resist layer is formed in a plating bath In addition, the step of forming a through electrode penetrating the semiconductor substrate by burying a conductor in the through hole by applying a plating process by energizing the plating base film, and the semiconductor subjected to the plating process And a step of removing the plating resist layer from the lower surface of the substrate and removing the plating base film exposed on the lower surface of the semiconductor substrate after the peeling.

  In the above manufacturing method, the plating metal layer is deposited only on the exposed portion of the plating base film without being covered with the plating resist layer during the plating process on the back surface of the semiconductor substrate. At this time, in the manufacturing method described above, the plating resist layer is formed including the portion of the through hole, and therefore the plating layer of the conductor is not deposited on the portion of the through hole. On the other hand, since the plating resist layer is formed so as to exclude the through-hole portion, a conductive plating layer is deposited in the through-hole. Therefore, in the above manufacturing method, selective etching of the conductive material (copper) into the through hole is performed easily and accurately while the through hole and the through hole are simultaneously etched and formed while the through hole is hollow. Can do.

  In the semiconductor sensor chip manufactured in this way, the diaphragm formed on the upper surface of the semiconductor substrate can be directly electrically connected to the lower surface of the semiconductor substrate via the through electrode. Therefore, problems associated with wire bonding, such as an increase in mounting area, generation of manufacturing defects due to ultrasonic vibration, and increase in production cost, can be solved. Therefore, according to the manufacturing method described above, it is possible to more effectively improve the productivity of manufacturing the semiconductor sensor chip itself and mounting it.

According to a third aspect of the present invention, a diaphragm is formed on the upper surface of the semiconductor substrate, and a through-hole penetrating from the upper surface of the semiconductor substrate to the lower surface thereof is formed at the position where the diaphragm is formed on the semiconductor substrate. A method of manufacturing a semiconductor sensor chip, wherein the lower surface side is opened from the lower surface of the semiconductor substrate and the upper surface side is opened from the upper surface of the semiconductor substrate, and the upper surface side is opened from the upper surface of the semiconductor substrate. A step of forming through holes through the upper surface and the lower surface of the semiconductor substrate at the same time by etching so that the lower surface side is closed, and embedding a conductor into the through hole from the opening of the upper surface of the semiconductor substrate, The gist of the present invention is the step of forming a through electrode penetrating the semiconductor substrate.

  In the above manufacturing method, when the through hole and the through hole are simultaneously etched, the through hole is etched from the upper surface side of the semiconductor substrate, and the through hole is etched from the lower surface side of the semiconductor substrate. Open to different surfaces. Therefore, while the through hole and the through hole are simultaneously formed by etching, the inside of the through hole is made hollow by embedding a conductor from the upper surface side of the semiconductor substrate where the through hole is opened and the through hole is closed. As it is, the conductor can be embedded in only the through hole easily and accurately.

  In the semiconductor sensor chip manufactured in this way, the diaphragm formed on the upper surface of the semiconductor substrate can be directly electrically connected to the lower surface of the semiconductor substrate via the through electrode. Therefore, problems associated with wire bonding, such as an increase in mounting area, generation of manufacturing defects due to ultrasonic vibration, and increase in production cost, can be solved. Therefore, according to the manufacturing method described above, it is possible to more effectively improve the productivity of manufacturing the semiconductor sensor chip itself and mounting it.

  According to the method for manufacturing a semiconductor sensor chip of the present invention, productivity can be effectively improved.

(First embodiment)
Hereinafter, a first embodiment embodying a method of manufacturing a semiconductor sensor chip according to the present invention will be described in detail with reference to FIGS. Here, an application example of the present invention to manufacture of a semiconductor sensor chip for a capacitance sensing type semiconductor microphone in which a counter electrode serving as an acoustic detection unit is formed on a semiconductor substrate will be described. In the following description, in the semiconductor sensor chip and its semiconductor substrate (silicon wafer), the surface on the side where the MEMS structure including the diaphragm is formed is described as “upper surface”, and the opposite surface is described as “lower surface”. To do.

  The semiconductor sensor is used as a package module in which a semiconductor sensor chip 10 is accommodated in a package 11 and its cross-sectional structure is shown in FIG. The package 11 includes a printed wiring board 12 and a cover 13 attached so as to cover the upper surface thereof. The semiconductor sensor chip 10 is bonded to the upper surface of the printed wiring board 12 by an adhesive 15 together with an IC chip 14 having a control IC formed on the semiconductor substrate. The semiconductor sensor chip 10 and the IC chip 14 are electrically connected to each other via wiring formed on the upper surface of the printed wiring board 12. The cover 13 is formed with a sound hole 16 that communicates the inside and the outside. The acoustic vibration is propagated from the outside to the acoustic detection portion of the semiconductor sensor chip 10 in the package 11 through the sound hole 16.

  Next, details of the semiconductor sensor chip 10 will be described with reference to FIGS.

As shown in FIG. 2A, the upper surface structure of the semiconductor sensor chip 10 includes a movable diaphragm electrode 21 and a fixed electrode 22 that form counter electrodes that serve as capacitors. The movable diaphragm electrode 21 and the fixed electrode 22 are respectively connected by wiring to an aluminum electrode pad 23 formed on the upper surface of the semiconductor substrate 20. 2B, a plurality of solder balls 24 are mounted on the peripheral edge of the lower surface side of the semiconductor substrate 20 at intervals. These solder balls 24 are brought into contact with the upper surface of the printed circuit board 12 (see FIG. 1) when bonded.

  As shown in the cross-sectional structure of FIG. 3, a through hole 27 that penetrates from the upper surface of the semiconductor substrate 20 to its lower surface is formed at the position where the counter electrode (movable diaphragm electrode 21, fixed electrode 22) of the semiconductor substrate 20 is formed. Is formed. Insulating protective films 25, 26, 38, and 39 made of silicon oxide (SiO2) are formed on the upper and lower surfaces of the semiconductor substrate 20, respectively. The entire upper surface side of the fixed electrode 22 is fixed by an insulating protective film 25. A gap (air gap) is formed between the fixed electrode 22 and the movable diaphragm electrode 21. As a result, the movable diaphragm electrode 21 is fixed only at its peripheral edge, and both the upper surface side and the lower surface side of the center portion are completely separated from the surrounding structure. The fixed electrode 22 has a plurality of air vent holes 22a for venting air from the air gap.

  On the other hand, through holes 34 penetrating from the upper surface to the lower surface of the semiconductor substrate 20 are formed from the electrode pads 23 on the upper surface of the semiconductor substrate 20 to which the movable diaphragm electrode 21 and the fixed electrode 22 are connected. A conductor (for example, copper) is embedded in the through hole 34. As a result, a through electrode 28 that connects the upper surface and the lower surface of the semiconductor substrate 20 is formed. A wiring 29 is formed on the lower surface of the semiconductor substrate 20 to electrically connect the through electrode 28 and a part of the solder ball 24.

  As shown in the enlarged sectional structure in FIG. 4, a metal barrier layer 30 and an insulating protective film 31 are formed around the through electrode 28. The metal barrier layer 30 is made of, for example, titanium (Ti), titanium nitride (TiN), tantalum (Ta), or tantalum nitride (TaN). The insulating protective film 31 is made of silicon oxide. The through electrode 28 and the semiconductor substrate 20 are isolated by the metal barrier layer 30 and the insulating protective film 31.

  In such a semiconductor sensor chip 10, the counter electrode (movable diaphragm electrode 21, fixed electrode 22) formed on the upper surface side of the semiconductor substrate 20 is mounted on the lower surface side of the semiconductor substrate 20 via the through electrode 28. Electrical connection is made to the solder balls 24. As a result, the counter electrode can be directly electrically connected to the wiring of the printed wiring board 12 (see FIG. 1), and wire bonding is not required, resulting in an increase in mounting area, production defects due to ultrasonic vibration, and production. It is possible to eliminate problems such as an increase in cost and further improve productivity.

  When manufacturing the semiconductor sensor chip 10 as described above, it is necessary to form two types of holes penetrating the semiconductor substrate 20, the through hole 27 behind the movable diaphragm electrode 21 and the through hole 34 for the through electrode 28. There is. Such holes can be formed by etching the semiconductor substrate 20. However, the simultaneous etching formation of the through hole 27 and the through hole 34 has the following problems. That is, in order to form the through electrode 28, it is necessary to embed a conductor in the through hole 34. However, in a normal method, the through hole 27 is left hollow, and only the through hole 34 is selectively filled with the conductor. It is difficult to embed, and there is a possibility that the conductor is embedded in the through hole 27 simultaneously with the through hole 34. However, if the through hole 27 and the through electrode 28 are formed in the semiconductor substrate 20 in the order of etching formation of the through hole 34, embedding of the conductor in the through hole 34, and etching formation of the through hole 27, the conductor is embedded. It is possible to make a selection of holes. However, in this case, the through holes 27 and the through holes 34 must be individually formed by etching, resulting in an increase in man-hours.

Therefore, in this embodiment, by applying a processing technique called a semi-additive method, which is used in a subsequent process of a printed circuit board or a semiconductor device, as shown in Patent Document 3, to the semiconductor substrate 20, a through hole is formed in the semiconductor substrate 20. 27 and the through electrode 28 can be easily formed. The semi-additive method is a technique for selectively forming a plating layer on a necessary portion of the upper surface of the substrate through the following procedures (A) to (E), and is generally used in a subsequent process of a printed circuit board or a semiconductor device. Yes. In the present embodiment, in the following procedure (B), by forming the plating resist layer so as to include the portion of the through hole 27 on the lower surface of the semiconductor substrate 20 and exclude the portion of the through hole 34, only in the through hole 34, A conductor is selectively embedded.

  (A) Formation of a conductive film (plating base film) to be a plating electrode on the entire substrate surface on which the plating layer is to be formed.

  (B) Formation of a selective plating resist layer on a plating unnecessary portion by patterning using a photolithography technique or the like.

  (C) Plating treatment of the substrate surface through immersion in a plating bath and feeding to the plating base film. In this case, the plating metal is selectively deposited only on the exposed portion of the plating base film on the surface of the substrate without the plating resist layer.

  (D) Peeling of the plating resist layer.

  (E) Removal of the plating base film remaining on the plating unnecessary portion by etching using the deposited plating metal layer (plating layer) as a mask (etch back).

  Hereinafter, details of the manufacturing procedure of the semiconductor sensor chip 10 in the present embodiment including the formation of the through electrode 28 applying such a semi-additive method will be described in detail with reference to FIGS. The semiconductor sensor chip 10 is manufactured by simultaneously forming a large number of chips on a silicon wafer and then separating them into individual chips. The manufacture of the semiconductor sensor chip 10 is performed in the order of the following steps 1 to 12.

(Step 1) Formation of MEMS Structure When the semiconductor sensor chip 10 is manufactured, the MEMS structure is first formed on the upper surface of the silicon wafer 32 (semiconductor substrate 20). Prior to this, insulating protection films 25 and 26 of silicon oxide (SiO2) are formed on the upper and lower surfaces of the silicon wafer 32 by oxidation treatment.

  The formation of the MEMS structure is performed through a general semiconductor process. That is, by sequentially stacking the necessary structures on the upper surface of the semiconductor substrate 20 while patterning using photolithography or the like, as shown in FIG. 5A, the movable diaphragm electrode 21, the fixed electrode 22, the electrode pad 23, and A MEMS structure such as wiring for electrically connecting them is formed. At this time, a sacrificial layer 33 is formed in the air gap between the movable diaphragm electrode 21 and the fixed electrode 22 or in the air vent hole 22a. Further, an insulating protective film 38 is formed on the upper surface side of the silicon wafer 32 so as to cover the formed MEMS structure.

(Step 2) Etching of Through Hole and Through Hole In this step, as shown in FIG. 5 (b), etching is performed from the lower surface side of the silicon wafer 32 (semiconductor substrate 20) on which the MEMS structure is formed. A through hole 27 and a through hole 34 penetrating from the lower surface to the upper surface of 32 are simultaneously formed. The through hole 27 is formed at a position where the movable diaphragm electrode 21 of the silicon wafer 32 is formed. The through hole 34 is formed at the position where the electrode pad 23 is formed on the silicon wafer 32.

(Step 3) Formation of Insulating Protective Film In this step, an insulating protective film 31 of silicon oxide (SiO2) is formed on the lower surface of the silicon wafer 32 in which the through holes 27 and the through holes 34 are formed, as shown in FIG. Is deposited.

(Step 4) Bottom Etching of Insulating Protective Film In this step, as shown in FIG. 5D, bottom etching is performed on the lower surface side of the silicon wafer 32 to remove the unnecessary insulating protective film 31. Thereby, the insulating protective film 31 formed in the previous step 3 is left only on the side peripheral surfaces of the through hole 27 and the through hole 34.

  After the above steps 1 to 4, the through electrode 28 is formed through the following steps 5 to 8 by applying the semi-additive method described above.

(Step 5) Plating Ground Treatment In this step, ground treatment for performing copper plating on the lower surface of the silicon wafer 32 is performed. Specifically, a plating base film 36 in which a metal barrier layer 30 (see FIG. 4) made of titanium nitride (TiN), a plating catalyst (Pb) layer, and a base copper plating layer are sequentially laminated on the entire lower surface of the silicon wafer 32, It is formed as shown in FIG.

(Step 6) Formation of Plating Resist Layer In this step, a non-conductive plating resist layer 37 is formed on the lower surface of the silicon wafer 32 as shown in FIG. The plating resist layer 37 is patterned by a photolithography technique and is selectively formed only at a portion where plating is not required. Specifically, the plating resist layer 37 is a silicon wafer 32 excluding a portion of the through hole 34 and a portion where the wiring 29 (see FIG. 3) for electrically connecting the through electrode 28 and the solder ball 24 is formed. It is formed on the entire lower surface. Thus, the plating resist layer 37 is formed on the lower surface side of the silicon wafer 32 (semiconductor substrate 20) so as to include the through hole 27 and exclude the through hole 34.

(Step 7) Plating treatment In this step, copper plating is performed on the lower surface side of the silicon wafer 32. Copper plating is performed by immersing the silicon wafer 32 in a plating bath and energizing the plating base film 36 as a plating electrode. At this time, copper, which is a plating metal, is not covered with the plating resist layer 37 and is selectively deposited only on the exposed portion of the plating base film 36. As a result, as shown in FIG. 6C, the copper plating layer 40 is selectively formed only in the inside of the through hole 34 on the lower surface of the silicon wafer 32 and in the formation position of the wiring 29 (see FIG. 3). It becomes like this.

(Step 8) Plating resist layer peeling and etch back In this step, the plating resist layer 37 remaining on the lower surface of the silicon wafer 32 after copper plating is removed, and the plating underlying film 36 remaining (etch back) is also removed. Do. The plating resist layer 37 is peeled by immersing the silicon wafer 32 in a stripping solution. Further, the plating base film 36 is removed by wet etching using, for example, an iron chloride solution, using the formed copper plating layer 40 as a mask.

  As described above, the through electrode 28 and the wiring 29 made of copper are formed in the silicon wafer 32 as shown in FIG. Thereafter, in the present embodiment, the following steps 9 to 12 are performed.

(Step 9) Formation of Insulating Protective Film In this step, as shown in FIG. 7A, the lower surface of the silicon wafer 32 on which the through electrode 28 and the wiring 29 are formed is covered with an insulating protection made of silicon oxide so as to cover them. A film 39 is formed. At this time, the insulating protective film 39 is formed in a state where the mounting position of the solder ball 24 is masked.

(Step 10) Removal of Sacrificial Layer In this step, as shown in FIG. 7B, the sacrificial layer 33 formed inside the air gap between the movable diaphragm electrode 21 and the fixed electrode 22 and the air vent hole 22a, The silicon wafer 32 is removed by etching from the upper surface side. Thereby, a space is formed inside the MEMS structure.

(Step 11) Mounting of Solder Balls In this step, as shown in FIG. 7C, the solder balls 24 are mounted on necessary portions of the lower surface of the silicon wafer 32. As described above, all the structures constituting each semiconductor sensor chip 10 are formed on the silicon wafer 32.

(Step 12) Dicing In this step, the silicon wafer 32 for each semiconductor sensor chip 10 is separated.

  Thereafter, the semiconductor sensor chip 10 thus manufactured is mounted on the printed wiring board 12 (see FIG. 1) and accommodated in the package 11 (also see FIG. 1), thereby completing the semiconductor microphone module.

  According to the manufacturing method of the semiconductor sensor chip of the present embodiment described above, the following effects can be obtained.

  (1) In the semiconductor sensor chip 10 manufactured through the manufacturing method of the present embodiment, the counter electrode (movable diaphragm electrode 21, fixed electrode 22) formed on the upper surface side of the semiconductor substrate 20 is connected via the through electrode 28. The solder balls 24 mounted on the lower surface side of the semiconductor substrate 20 are electrically connected. Therefore, it becomes possible to electrically connect the counter electrode directly to the wiring of the printed wiring board 12, and wire bonding is not required. Therefore, there are problems such as an increase in mounting area, production defects due to ultrasonic vibration, and an increase in production cost. Can be eliminated.

  (2) In the manufacturing method of the present embodiment, the through hole 27 formed through the semiconductor substrate 20 and the through electrode 28 that also penetrates the semiconductor substrate 20 are formed behind the movable diaphragm electrode 21. The through hole 34 is simultaneously formed by etching. Thereby, the man-hour concerning the etching for forming each of the through hole 27 and the through hole 34 can be reduced.

  (3) In the manufacturing method of this embodiment, the conductor (copper) is embedded in the through hole 34 by applying the semi-additive method. Therefore, the conductive material (copper) can be selectively buried in the through hole 34 easily and accurately while the inside of the through hole 27 is hollow.

(Second Embodiment)
Next, a second embodiment that embodies the semiconductor sensor chip manufacturing method according to the present invention will be described with reference to FIGS. 8 to 10, focusing on differences from the first embodiment. In addition, in this embodiment, about the member which comprises the function and structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

In the present embodiment, when the through hole 27 and the through hole 34 are simultaneously formed by etching, the through hole 27 is etched from the lower surface side of the semiconductor substrate 20, and the through hole 34 is etched from the upper surface side of the semiconductor substrate 20. The hole 27 and the through hole 34 are opened on different surfaces of the semiconductor substrate 20. Therefore, while the through hole 27 and the through hole 34 are simultaneously formed by etching, the conductor is embedded from the upper surface side of the semiconductor substrate 20 where the through hole 34 is opened and the through hole 27 is closed. The conductor is easily and accurately embedded only in the through hole 34 while the inside of the space 27 is hollow.

  Hereinafter, the details of the manufacturing procedure of the semiconductor sensor chip 10 ′ in this embodiment will be described in detail based on FIGS. 8 to 10. In the semiconductor sensor chip 10 ′, the layout of some components has been changed for the convenience of etching the through holes 27 and the through holes 34 as described above. The semiconductor sensor chip 10 has the same configuration. Manufacture of semiconductor sensor chip 10 'in this embodiment is performed in order of the following processes 1-12.

(Step 1) Formation of MEMS Structure In this step, the MEMS structure is formed on the upper surface of the silicon wafer 32 (semiconductor substrate 20) as shown in FIG. 8A, as in the first embodiment.

(Step 2) Etching of Through Hole and Through Hole In this step, the through hole 27 and the through hole 34 are simultaneously formed by etching. Etching at this time is performed on a portion other than the position where the through hole 34 (through electrode 28) is formed on the upper surface side of the silicon wafer 32 and on a portion other than the position where the through hole 27 is formed on the lower surface side of the silicon wafer 32. Each is performed with masking applied. For this etching, dry etching or wet etching can be applied. In the case of dry etching, by using batch processing for simultaneously processing a plurality of wafers, as shown in FIG. 8B, the through hole 27 is from the lower surface side of the silicon wafer 32 and the through hole 34 is silicon wafer 32. The anisotropic etching is performed from the upper surface side of each. On the other hand, in the case of wet etching, by immersing the silicon wafer 32 in an alkaline etching solution, the through hole 27 is from the lower surface side of the silicon wafer 32, and the through hole 34 is from the upper surface side of the silicon wafer 32, respectively. Anisotropic etching is performed. Thereby, the through hole 27 is formed so that the lower surface side of the silicon wafer 32 is opened and the upper surface side thereof is closed by a MEMS structure or the like. The through hole 34 is formed such that the upper surface side of the silicon wafer 32 is opened and the lower surface side thereof is closed by an insulating protective film 26 made of silicon oxide.

  In the present embodiment, the through hole 34 (through electrode 28) is formed at a position different from the electrode pad 23 for the convenience of etching the through hole 34 from the upper surface side of the silicon wafer 32.

(Step 3) Formation of Insulating Protective Film In this step, an insulating protective film 31 of silicon oxide (SiO2) is formed on the side peripheral wall of the through hole 34, as shown in FIG. Specifically, after forming an insulating protective film 31 of silicon oxide on the entire upper surface side of the silicon wafer 32, bottom insulating is performed so that the insulating protective film 31 remains only on the side peripheral wall of the through hole 34. I have to.

(Step 4) Opening on Upper Surface of Electrode Pad In this step, as shown in FIG. 8D, the insulating protective film 38 on the upper surface of the electrode pad 23 is removed by etching to expose the electrode pad 23. This processing is performed to form a wiring that electrically connects the electrode pad 23 and the through electrode 28 (through hole 34) formed at different positions as described above.

(Step 5) Plating ground treatment In this embodiment, ground treatment for performing copper plating is performed on the upper surface side of the silicon wafer 32 in this step. Specifically, titanium nitride (Ti
N) etc., after forming a metal barrier layer, a copper plating seed layer is embedded in the surface by sputtering, so that the entire upper surface side of the silicon wafer 32 is plated as shown in FIG. A base film 36 is formed.

(Step 6) Plating treatment In this step, copper plating is performed on the upper surface side of the silicon wafer 32. Copper plating is performed by immersing the upper surface side of the silicon wafer 32 in a plating bath and energizing the plating base film 36 as a plating electrode. Thereby, as shown in FIG. 9B, the copper plating layer 41 is formed on the entire upper surface side of the silicon wafer 32 including the inside of the through hole 34.

(Step 7) Etching of Plating Layer In this step, unnecessary portions of the copper plating layer 41 formed on the upper surface side of the silicon wafer 32 are removed by etching. Thereby, as shown in FIG. 9C, the copper plating layer 41 is formed in a portion inside the through hole 34 that forms the through electrode 28 and the through electrode 28 and electrode pad 23 formed on the upper surface of the silicon wafer 32. It remains only in the portion of the wiring 42 between them.

(Step 8) Formation of Insulating Protective Film In this step, as shown in FIG. 9 (d), silicon oxide is insulated so as to cover the upper surface side of the silicon wafer 32 on which the through electrode 28 and the wiring 42 are formed. A protective film 43 is formed.

(Step 9) Removal of Sacrificial Layer In this step, as shown in FIG. 10A, the sacrificial layer 33 formed inside the air gap between the movable diaphragm electrode 21 and the fixed electrode 22 and the air vent hole 22a, The silicon wafer 32 is removed by etching from the upper surface side. Thereby, a space is formed inside the MEMS structure.

(Step 10) Etching of Insulating Protective Film In this step, as shown in FIG. 10B, the insulating protective film 26 on the lower surface side of the silicon wafer 32 at the position where the through electrode 28 is formed is removed by etching.

(Step 11) Formation of Bumps In this step, as shown in FIG. 10C, bumps 44 are formed on the lower surface of the silicon wafer 32 at the positions where the insulating protective film 26 has been removed. The bumps 44 serve as terminals for electrically connecting the wirings on the printed wiring board 12 and the through electrodes 28 when the semiconductor sensor chip 10 ′ is mounted on the printed wiring board 12 (see FIG. 1).

(Step 12) Dicing In this step, the silicon wafer 32 is separated for each semiconductor sensor chip 10 ′. Thus, the semiconductor sensor chip 10 ′ as shown in FIG. 10D is manufactured.

  According to the manufacturing method of the semiconductor sensor chip of the present embodiment described above, in addition to the effects described in (1) and (2) above, the following effects can be further achieved.

(4) In the present embodiment, when the through hole 27 and the through hole 34 are simultaneously etched, the through hole 27 is etched from the lower surface side of the silicon wafer 32, and the through hole 34 is etched from the upper surface side of the silicon wafer 32. I have to. Thereby, the through hole 27 and the through hole 34 are opened on different surfaces of the silicon wafer 32. Therefore, the conductive hole (copper) is embedded (plated) from the upper surface side of the silicon wafer 32 in which the through hole 34 is opened and the through hole 27 is closed while the through hole 27 and the through hole 34 are simultaneously etched. By doing so, it is possible to easily and accurately embed a conductor only in the through hole 34 while keeping the inside of the through hole 27 hollow.

  Each embodiment described above can be implemented with the following modifications.

  -The detail of the processing aspect in each process in the said embodiment may be changed suitably as needed. Further, the order of each process may be changed, or a part thereof may be omitted.

  The manufacturing method of the present invention can also be applied to semiconductor sensor chips having configurations other than the semiconductor sensor chips 10 and 10 ′ exemplified in the above embodiments. For example, the present invention can be applied to the manufacture of a semiconductor sensor chip having a configuration in which a MEMS structure constituting a detection portion of a sensor and an integrated circuit for sensor control are integrated. The present invention can also be applied to other capacitance sensing type semiconductor sensors such as a pressure sensor and an acceleration sensor. Furthermore, even if a semiconductor sensor other than a capacitance sensing type is provided with a diaphragm formed on a semiconductor substrate, the manufacturing method of the present invention can be applied in a manner similar to or equivalent to the above embodiment. it can.

Sectional drawing which shows the side part cross-section of the package in which the semiconductor sensor chip manufactured with the manufacturing method of 1st Embodiment of this invention is accommodated. The top view which shows (a) upper surface structure and (b) lower surface structure of the semiconductor sensor chip manufactured with the manufacturing method of the embodiment, respectively. Sectional drawing which shows the side part cross-section of the semiconductor sensor chip. Sectional drawing which shows the expanded sectional structure of the through-electrode vicinity of the semiconductor sensor chip. (A)-(d) Sectional drawing which each shows the cross-section of a semiconductor sensor chip in each process in the manufacturing method of the embodiment. (A)-(d) Similarly sectional drawing which shows the cross-sectional structure of the semiconductor sensor chip in each process. (A)-(c) Sectional drawing which each shows the cross-section of a semiconductor sensor chip in each process. (A)-(d) Sectional drawing which each shows the cross-sectional structure of the semiconductor sensor chip in each process about the manufacturing method of 2nd Embodiment of this invention. (A)-(d) Similarly sectional drawing which shows the cross-sectional structure of the semiconductor sensor chip in each process. (A)-(d) Similarly sectional drawing which shows the cross-sectional structure of the semiconductor sensor chip in each process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,10 '... Semiconductor sensor chip, 11 ... Package, 12 ... Printed wiring board, 13 ... Cover, 14 ... IC chip, 15 ... Adhesive, 16 ... Sound hole, 20 ... Semiconductor substrate, 21 ... Variable diagram electrode, 22 ... Fixed electrode, 22a ... Air vent hole, 23 ... Electrode pad, 24 ... Solder ball, 25, 26, 31, 38, 39 ... Insulating protective film, 27 ... Through hole, 28 ... Through electrode, 29, 42 ... Wiring, DESCRIPTION OF SYMBOLS 30 ... Metal barrier layer, 32 ... Silicon wafer, 33 ... Sacrificial layer, 34 ... Through-hole, 36 ... Plating base film, 37 ... Plating resist layer, 40 ... Copper plating layer, 44 ... Bump.

Claims (3)

A method of manufacturing a semiconductor sensor chip in which a diaphragm is formed on an upper surface of a semiconductor substrate and a through-hole penetrating from the upper surface of the semiconductor substrate to the lower surface is formed at a position where the diaphragm is formed on the semiconductor substrate. And
Forming a through hole penetrating the upper surface and the lower surface of the semiconductor substrate by etching simultaneously with the through hole;
Forming a through electrode penetrating the semiconductor substrate by burying a conductor in the formed through hole;
A method for manufacturing a semiconductor sensor chip, comprising: A method of manufacturing a semiconductor sensor chip in which a diaphragm is formed on an upper surface of a semiconductor substrate and a through-hole penetrating from the upper surface of the semiconductor substrate to the lower surface is formed at a position where the diaphragm is formed on the semiconductor substrate. And
Forming a through hole penetrating the upper surface and the lower surface of the semiconductor substrate by etching simultaneously with the through hole;
Forming a conductive plating base film on a lower surface of the semiconductor substrate in which the through hole and the through hole are formed;
Forming a plating resist layer on the lower surface of the semiconductor substrate on which the plating base film is formed, including the through-hole portion and excluding the through-hole portion;
By immersing the lower surface of the semiconductor substrate on which the plating resist layer is formed in a plating bath and energizing the plating base film to perform a plating process, a conductor is embedded in the through hole to penetrate the semiconductor substrate. Forming a through electrode to be
Peeling the plating resist layer from the lower surface of the semiconductor substrate subjected to the plating treatment, and removing the plating base film exposed on the lower surface of the semiconductor substrate after the peeling;
A method for manufacturing a semiconductor sensor chip, comprising: A method of manufacturing a semiconductor sensor chip in which a diaphragm is formed on an upper surface of a semiconductor substrate and a through-hole penetrating from the upper surface of the semiconductor substrate to the lower surface is formed at a position where the diaphragm is formed on the semiconductor substrate. And
The through-hole is opened so that the lower surface side is opened from the lower surface of the semiconductor substrate and the upper surface side is closed, and the upper surface of the semiconductor substrate is opened so that the upper surface side is opened from the upper surface of the semiconductor substrate and the lower surface side is closed. Forming through-holes penetrating through the lower surface and the lower surface simultaneously by etching,
Burying a conductor in the through hole from the opening on the upper surface of the semiconductor substrate to form a through electrode penetrating the semiconductor substrate;
A method for manufacturing a semiconductor sensor chip, comprising:

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