News Column

Patent Issued for Method of Making Semiconductor Device

August 6, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Sugiura, Kazuhiko (Nagoya, JP); Fujii, Tetsuo (Toyohashi, JP); Yokura, Hisanori (Obu, JP), filed on January 24, 2013, was published online on July 22, 2014.

The patent's assignee for patent number 8785231 is DENSO CORPORATION (Kariya, JP).

News editors obtained the following quote from the background information supplied by the inventors: "JP-2004-333133A discloses an inertial sensor having a device layer where a movable portion is formed. The device layer is sandwiched between upper and lower substrates so that the movable portion of the device layer can be sealed by the upper and lower substrates. The upper substrate serves as a cap for covering the movable portion and prevents entry of a foreign matter such as water into the movable portion.

"The upper substrate has a through hole where the device layer is exposed. A pad formed in the device layer is exposed through the through hole, and a bonding wire is directly connected to the exposed pad so that the device layer can be electrically connected to external circuitry.

"Such an inertial sensor is manufactured as follows. Firstly, the device layer and the lower substrate are joined together, and the movable portion is formed in the device layer. Then, the upper substrate having the through hole is joined to the device layer in such a manner that the through hole of the upper substrate can be aligned with the pad of the device layer. Then, the bonding wire is connected to the pad that is exposed through the through hole.

"The through hole of the upper substrate is sized to be large enough to prevent the bonding wire from touching the upper substrate. Therefore, there is a problem that a chip size becomes large due to the large through hole. Further, there is another problem that a surface area of the upper substrate becomes small due to the large through hole. Accordingly, strength of the upper substrate is reduced, and there arises a difficulty in handling such as holding and carrying the upper substrate."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "In view of the above, it is an object of the present invention to provide a semiconductor device having a structure for improving a handling of a cap and for reducing a size of the semiconductor device. It is another object of the present invention to provide a method of making the semiconductor device.

"According to a first aspect of the present invention, a method of making a semiconductor device includes preparing a sensor wafer having one side and including a plurality of sensor portions. Each sensor portion has one surface on the side of the sensor wafer and includes a sensor structure at a surface portion of the surface. The method further includes preparing a cap wafer having a front side and a back side opposite to the front side and including a plurality of cap portions. Each cap portion has a first surface on the front side of the cap wafer and a second surface on the back side of the cap wafer. The method further includes forming a trench on the first surface of the cap portion, forming an insulation layer on a wall of the trench, and forming a buried electrode on the insulation layer. The method further includes joining the side of the sensor wafer to the front side of the cap wafer such that the buried electrode of the cap portion is electrically connected to a contact region of the sensor structure of the sensor portion and such that the sensor structure is sealed between the sensor portion and the cap portion. The method further includes forming a through hole and a through electrode extending from the first surface to the second surface of the cap portion by removing the back side of the cap wafer until the trench and the buried electrode are exposed to a new surface of the back side of the cap wafer. The method further includes dividing a joined body of the sensor wafer and the cap wafer into a plurality of semiconductor devices in the form of chips after the forming of the through electrode.

"According to a second aspect of the present invention, a method of making a semiconductor device includes preparing a sensor wafer having one side and including a plurality of sensor portions. Each sensor portion has one surface on the side of the sensor wafer and includes a sensor structure at a surface portion of the surface and a connection portion electrically connected to the sensor structure. The connection portion is located within a connection region on an outer region of the surface. The connection region of a first one of the plurality sensor portions faces the connection region of a second one of the plurality of sensor portions to form a cavity region between the sensor structure of the first one of the plurality sensor portions and the sensor structure of the second one of the plurality sensor portions. The method further includes preparing a cap wafer having a front side and a back side opposite to the front side and including a plurality of cap portions. Each cap portion has a first surface on the front side of the cap wafer and a second surface on the back side of the cap wafer. The method further includes forming a recessed portion on the front side of the cap wafer. The method further includes joining the side of the sensor wafer to the front side of the cap wafer such that the cavity region of the sensor wafer is covered with a bottom of the recessed portion of the cap wafer and such that the sensor structure is sealed between the sensor portion and the cap portion. The method further includes forming an ion-implanted layer in the cap wafer by implanting a plurality of ions into the back side of the cap wafer. The ion-implanted layer is located at a depth equal to or greater than the bottom of the recessed portion measured from the back side of the cap wafer. The method further includes thermally treating a joined body of the sensor wafer and the cap wafer after the forming of the ion-implanted layer. The method further includes separating the back side of the cap wafer with respect to the ion-implanted layer as a cleavage surface to remove the bottom of the recessed portion after the thermally treating of the joined body, so that the cavity region is exposed to a new surface of the back side of the cap wafer through the recessed portion. The method further includes dividing the joined body of the sensor wafer and the cap wafer into a plurality of semiconductor devices in the form of chips after the separating of the back side, so that the connection region of the sensor portion is exposed through the cap portion.

"According to a third aspect of the present invention, a method of making a semiconductor device includes preparing a sensor wafer having one side and including a plurality of sensor portions. Each sensor portion has one surface on the side of the sensor wafer and including a sensor structure at a surface portion of the surface and a connection portion electrically connected to the sensor structure. The connection portion is located within a connection region on an outer region of the surface. The connection region of a first one of the plurality of sensor portions faces the connection region of a second one of the plurality of sensor portions to form a cavity region between the sensor structure of the first one of the plurality sensor portions and the sensor structure of the second one of the plurality sensor portions. The method further includes preparing a cap wafer having a front side and a back side opposite to the front side and including a plurality of cap portions. Each cap portion has a first surface on the front side of the cap wafer and a second surface on the back side of the cap wafer. The method further includes forming a recessed portion on the front side of the cap wafer. The method further includes joining the side of the sensor wafer to the front side of the cap wafer such that the cavity region of the sensor wafer is covered with a bottom of the recessed portion of the cap wafer and such that the sensor structure is sealed between the sensor portion and the cap portion. The method further includes etching the back side of the cap wafer to remove the bottom of the recessed portion of the cap wafer, so that the cavity region is exposed to a new surface of the back side of the cap wafer through the recessed portion. The method further includes dividing a joined body of the sensor wafer and the cap wafer into a plurality of semiconductor devices in the form of chips after the separating of the back side, so that the connection region of the sensor portion is exposed through the cap portion.

"According to a fourth aspect of the present invention a semiconductor device includes a sensor portion, a cap portion, and an ion-implanted layer. The sensor portion has one surface and including a sensor structure at a surface portion of the surface and a connection portion electrically connected to the sensor structure. The cap portion has a first surface and a second surface opposite to the first surface. The cap portion includes a through hole extending from the first surface to the second surface, an insulation layer formed on a wall of the through hole, and a through electrode formed on the insulation layer. The through electrode extends from the first surface to the second surface through the through hole and electrically connected to the connection portion of the sensor portion. The ion-implanted layer is disposed on the second surface of the cap portion. The surface of the sensor portion is joined to the first surface of the cap portion such that the sensor structure is sealed between the sensor portion and the cap portion. The through electrode is exposed through the ion-implanted layer.

"According to a fifth aspect of the present invention, a semiconductor device includes a sensor portion, a cap portion, and an ion-implanted layer. The sensor portion has one surface and includes a sensor structure at a surface portion of the surface and a connection portion electrically connected to the sensor structure. The connection portion is located within a connection region on an outer region of the surface. The cap portion has a first surface and a second surface opposite to the first surface. The ion-implanted layer is disposed on the second surface of the cap portion. The surface of the sensor portion is joined to the first surface of the cap portion such that the sensor structure is sealed between the sensor portion and the cap portion and such that the connection region is exposed through the cap portion."

For additional information on this patent, see: Sugiura, Kazuhiko; Fujii, Tetsuo; Yokura, Hisanori. Method of Making Semiconductor Device. U.S. Patent Number 8785231, filed January 24, 2013, and published online on July 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8785231.PN.&OS=PN/8785231RS=PN/8785231

Keywords for this news article include: Electronics, Semiconductor, DENSO CORPORATION.

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Source: Electronics Newsweekly


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