CN211089591U - Integrated silicon oscillator structure - Google Patents
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- CN211089591U CN211089591U CN201920601608.8U CN201920601608U CN211089591U CN 211089591 U CN211089591 U CN 211089591U CN 201920601608 U CN201920601608 U CN 201920601608U CN 211089591 U CN211089591 U CN 211089591U
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Abstract
The integrated silicon oscillator structure comprises three resonator structures, an MEMS chip and a CMOS integrated circuit are integrated together through a bonding process, a silicon resonator, an independent MEMS silicon resonator and an integrated circuit chip are directly prepared on the CMOS integrated circuit; the MEMS resonator is integrated with the CMOS integrated circuit through a bonding process; the integrated silicon oscillator structure bonded with the CMOS circuit is divided into three structures; including silicon resonators with wire bond pads that can be bonded to CMOS integrated circuits, silicon resonators with through-silicon via metal connections that can be bonded to CMOS integrated circuits, and silicon resonators with thermal control that can be bonded to CMOS integrated circuits. The utility model has the advantages that: the shockproof effect is 25 times of that of the traditional quartz crystal oscillator product, and the quartz crystal oscillator has the characteristics of no influence of vibration and no easy breakage. The system also has the advantages of high integration level, programmability, small size, low power consumption and the like.
Description
Technical Field
The invention relates to the field of sensors, in particular to an integrated silicon oscillator structure.
Background
At present, a common oscillator in the market is a quartz oscillator, also called a quartz crystal oscillator. The quartz crystal oscillator is a quartz crystal resonator made of quartz materials, is commonly called as a crystal oscillator, and has the disadvantages of complex structure, complex preparation process and difficult production of conventional products.
Disclosure of Invention
The invention aims to realize reasonable structure and simplify the preparation process, and particularly provides an integrated silicon oscillator structure.
The invention provides an integrated silicon oscillator structure, which is characterized in that: the integrated silicon oscillator structure comprises three resonator structures, an MEMS chip and a CMOS integrated circuit are integrated together through a bonding process, a silicon resonator, an independent MEMS silicon resonator and an integrated circuit chip are directly prepared on the CMOS integrated circuit;
the MEMS resonator is integrated with the CMOS integrated circuit through a bonding process; the structure of the integrated silicon oscillator bonded with the CMOS circuit is divided into three structures:
the first structure is as follows: the silicon resonator with the lead bonding pad and capable of being bonded with the CMOS integrated circuit consists of a cavity wafer 1, a getter 5, a micro-resonator 3, a bonding area 2, the CMOS integrated circuit 6, the lead bonding pad 7 and a substrate 8;
the second structure is as follows: the silicon resonator which is connected with the silicon through hole metal and can be bonded with the CMOS integrated circuit consists of a cavity wafer 1, a getter 5, a micro-resonator 3, a bonding area 2, the CMOS integrated circuit 6, a silicon through hole 7 and a metal bump 8;
a third structure: a silicon resonator bondable to a CMOS integrated circuit with thermal control;
the device comprises a cavity wafer 1, a getter 5, a micro resonator 3, a bonding region 2, a CMOS integrated circuit 6, a silicon through hole 7 and a metal bump 8, a thermal control metal line 12 and a thermal isolation groove 13; the structure can always keep the temperature of the silicon resonator as a constant, and can provide stable output frequency when the external temperature environment changes greatly;
cavity wafer 1: the silicon wafer is composed of silicon, an SOI wafer and a silicon wafer with an epitaxial layer;
getter 2: the material is used as an important material for ensuring the vacuum environment in the cavity wafer and is composed of titanium or zirconium, iron or one or more of alloys or oxides thereof;
the micro resonator 3: the silicon wafer is composed of silicon, belongs to a part of a cavity wafer, and is prepared on the cavity wafer through photoetching, etching and other processes;
bonding region 4: the cavity wafer 1 and the CMOS integrated current wafer 5 are combined into a whole through a bonding process, the bonding area 4 is a connecting part of the cavity wafer 1 and the CMOS integrated current wafer 5, and the bonding process can be one of eutectic bonding, silicon-silicon direct bonding, glass slurry bonding and the like;
CMOS integrated circuit wafer 5: the resonator is made of silicon materials and provides an electrical processing function for the resonator;
wire bonding pad 6: the oscillator is made of metal materials such as Al and Cu and provides external electrical connection for the oscillator;
through silicon via 7: the silicon through hole is used for external electrical connection of the oscillator, and copper metal is filled in the silicon through hole to serve as an electrical medium;
metal bump 8: the through metal is connected with the through silicon via and used for electrical connection, and the through silicon via is composed of copper or other metal materials;
the thermal control metal 12: through the metal deposition process, heat is generated when current is passed through the metal deposition process, and the metal deposition process is used for adjusting the temperature of the silicon resonator, so that the temperature of the silicon resonator is always constant, and more stable frequency output is provided.
The position of the resonator and the crystal direction of the wafer need to form an angle of 0-45 degrees, so that the temperature performance is improved.
A method of fabricating an integratable silicon oscillator structure, the first method of fabrication: the MEMS resonator is integrated with the CMOS integrated circuit through a bonding process;
directly preparing a silicon resonator, an independent MEMS silicon resonator and an integrated circuit chip on a CMOS integrated circuit; the bonding process can be one of eutectic bonding, silicon-silicon direct bonding, glass slurry bonding and the like;
silicon oscillator process flow that can be integrated with CMOS circuit bonding:
preparing a silicon resonator structure 3 and a cavity structure on a cavity wafer 1 by using the processes of photoetching, etching, releasing and the like;
in the cavity wafer 1, a getter 5 is deposited around the silicon resonator 3 in the cavity wafer 1 by utilizing a physical vapor deposition technology;
a CMOS integrated circuit is manufactured on the substrate 8 by using a CMOS integrated circuit process;
after the CMOS integrated circuit is prepared, preparing a metal connecting wire which can also be used as metal in the bonding area 2;
the vacuum wafer bonding process can combine a cavity wafer 1 consisting of a silicon wafer or a glass wafer and an SOI wafer for preparing a silicon resonator and a CMOS integrated circuit into a whole by utilizing a eutectic bonding technology;
the second preparation method comprises the following steps: directly preparing a silicon oscillator on a CMOS integrated circuit;
the direct fabrication of silicon oscillators on CMOS integrated circuits is divided into two structures: directly preparing a silicon resonator on a CMOS integrated circuit and directly preparing a silicon piezoelectric resonator on the CMOS integrated circuit;
the silicon oscillator directly prepared on the CMOS integrated circuit consists of a cavity wafer 1, a bonding area 2, a silicon resonator 3, a buried oxide layer 4, a getter 5, the CMOS integrated circuit 6, a lead bonding area 7, a substrate 8, a piezoelectric lamination 9 and a silicon through hole connection 11; wherein 3, 4, 8 form an SOI wafer 10;
cavity wafer 1: is composed of a silicon wafer or a glass wafer;
bonding region 2: the cavity wafer 1 and the SOI wafer 10 are combined together by a bonding process, the bonding area 2 is a link part of the cavity wafer 1 and the SOI wafer 10 after bonding, the bonding process can be eutectic bonding, silicon-silicon bonding and other technologies, and the bonding area 2 can be made of silicon, Al, Ge and other materials;
silicon resonator 3: the silicon-based CMOS integrated circuit is prepared in a reserved area of the CMOS integrated circuit 6, and when the SOI wafer 10 made of heavily doped silicon is used, a lightly doped epitaxial layer is required to be prepared on the top silicon layer of the SOI wafer to prepare the CMOS integrated circuit 6; a plurality of silicon resonators 3 may be made in the entire oscillator structure;
and (4) an oxide layer: a buried oxide layer of silicon oxide, which is part of the SOI wafer 10;
getter 5: the material is used as an important material for ensuring the vacuum environment in the cavity wafer and is composed of titanium or zirconium, iron or one or more of alloys or oxides thereof;
CMOS integrated circuit 6: the CMOS integrated circuit is composed of silicon and metal Al or Cu and the like, and is an electrical processing part of the oscillator;
wire bonding region 7: the CMOS integrated circuit is made of CMOS integrated circuit compatible metal, such as Al, Cu and the like; the CMOS integrated circuit 6 is electrically connected with the outside;
substrate 8: composed of silicon, belonging to the bottom silicon part of the SOI wafer 10, the substrate of the CMOS integrated circuit 6;
the piezoelectric stack 9: since the resonator can be prepared by the pressure material, the resonator can be prepared on the CMOS integrated circuit 6 by the pressure lamination layer 9, and finally the silicon piezoelectric resonator directly prepared on the CMOS integrated circuit is formed; the pressure stack 9 is made of one of AlN aluminum nitride, AlScNA scandium-doped aluminum nitride, and PZT lead zirconate titanate piezoelectric ceramics;
SOI wafer 10: the silicon wafer is composed of silicon 3, a buried oxide layer 4 and substrate silicon 8, and is a material wafer for preparing a CMOS integrated circuit and a silicon resonator;
through-silicon via connection TSV 11: one of the electrical connection modes of the CMOS integrated circuit 6 and the outside is the same as that of the lead bonding region 7, and when the device does not have the bonding region 7, the CMOS integrated circuit can be electrically connected with the outside by using the through silicon via connection 11; the silicon through hole is prepared by the processes of photoetching, deep reactive ion etching, electroplating and the like, and metal compatible with a CMOS integrated circuit, such as Al and Cu, is filled in the silicon through hole;
the process flow of the silicon oscillator directly prepared on the CMOS integrated circuit comprises the following steps:
etching a deep groove on the top silicon of the SOI wafer by utilizing photoetching and deep reactive ion etching processes until reaching a buried oxide layer;
forming a heavily doped side wall on the side wall of the deep groove by using a doping process;
filling a deposition oxide layer in the deep groove by using a chemical vapor deposition method;
preparing a CMOS integrated circuit on the top silicon of the SOI wafer by using a CMOS integrated circuit process;
after the CMOS integrated circuit is prepared, preparing a metal connecting wire which can also be used as metal in the bonding area 2;
if the resonator is prepared by adopting the piezoelectric material, after the preparation of the CMOS integrated circuit is finished, the piezoelectric lamination can be deposited in a reserved area of the CMOS integrated circuit by utilizing a magnetron sputtering process to form the silicon resonator;
a gas hydrofluoric acid releasing process, wherein the filling oxide layer in the deep groove is etched and removed;
the vacuum wafer bonding process can combine a cavity wafer 1 consisting of a silicon wafer or a glass wafer and an SOI wafer for preparing a silicon resonator and a CMOS integrated circuit into a whole by utilizing a eutectic bonding technology; if a glass wafer is used as the cavity wafer 1, a laser adjustment process can be added to adjust the silicon resonator after bonding;
the third preparation method comprises the following steps: a separate MEMS silicon oscillator;
the single MEMS silicon oscillator is divided into a single MEMS silicon resonator and a single MEMS silicon piezoelectric resonator;
the device structure of the single MEMS silicon resonator consists of: the SOI wafer comprises a cavity wafer 1, a bonding region 2, a silicon resonator 3, a buried oxide layer 4, a getter 5, a wire bonding region 7, a substrate 8 and a piezoelectric lamination layer 9, wherein 3, 4 and 8 form an SOI wafer 10;
cavity wafer 1: is composed of a silicon wafer or a glass wafer;
bonding region 2: the cavity wafer 1 and the SOI wafer 10 are combined together by a bonding process, the bonding area 2 is a link part of the cavity wafer 1 and the SOI wafer 10 after bonding, the bonding process can be eutectic bonding, silicon-silicon bonding and other technologies, and the bonding area 2 can be made of silicon, Al, Ge and other materials;
silicon resonator 3: the silicon resonator is composed of silicon, belongs to the top silicon of the SOI wafer 10, and can also be composed of a doped epitaxial layer or polycrystalline silicon, and a plurality of silicon resonators 3 can be made in the whole oscillator structure;
and (4) an oxide layer: a buried oxide layer of silicon oxide, which is part of the SOI wafer 10;
getter 5: the material is used as an important material for ensuring the vacuum environment in the cavity wafer and is composed of titanium or zirconium, iron or one or more of alloys or oxides thereof;
wire bonding region 7: the CMOS integrated circuit is made of CMOS integrated circuit compatible metal, such as Al, Cu and the like; the oscillator is connected with an external electrical connection interface;
substrate 8: is composed of silicon and belongs to the bottom silicon portion of the SOI wafer 10;
the piezoelectric stack 9: since the resonator can also be prepared by the pressure material, the resonator can also be prepared by utilizing the pressure lamination layer 9 on the top silicon layer or the doped polysilicon layer or the epitaxial layer of the SOI wafer, and finally, the single MEMS silicon piezoelectric resonator is formed; the pressure stack 9 is made of one of AlN aluminum nitride, AlScN a scandium-doped aluminum nitride, and PZT lead zirconate titanate piezoelectric ceramics;
SOI wafer 10: the silicon substrate consists of top silicon 3, a buried oxide layer 4 and substrate silicon 8, and is a material wafer for preparing a CMOS integrated circuit and a silicon resonator;
single MEMS silicon oscillator process flow:
doping an SOI wafer or an epitaxial layer, and etching a deep groove on the top silicon of the SOI wafer by utilizing photoetching and deep reactive ion etching processes until an oxide layer is buried;
forming a heavily doped side wall on the side wall of the deep groove by using a doping process;
on the doped SOI wafer or epitaxial layer, a silicon resonator structure is prepared by utilizing photoetching and etching processes;
the silicon resonator can also be prepared by piezoelectric materials, and if the resonator is prepared by the piezoelectric materials, the silicon resonator is formed by depositing the piezoelectric lamination by utilizing a magnetron sputtering process;
preparing a cavity wafer 1 on a silicon wafer or a glass wafer by utilizing photoetching and etching processes;
the vacuum wafer bonding process can combine a cavity wafer 1 consisting of a silicon wafer or a glass wafer and a prepared silicon resonator SOI or epitaxial wafer into a whole by utilizing a eutectic bonding technology; if a glass wafer is used as the cavity wafer 1, a laser trimming process may be added after bonding to trim the silicon resonator.
The invention has the advantages that:
the integrated silicon oscillator structure, MEMS oscillator, is a programmable silicon oscillator manufactured by micro electro mechanical system, is an upgrade and update of the traditional quartz crystal oscillator product, has 25 times of shockproof effect, and has the characteristics of no vibration influence and no breakage. The temperature stability of the MEMS oscillator is better than that of the traditional crystal oscillator, and the MEMS oscillator is not influenced by the change of the ambient temperature. The frequency generating circuit has the advantages of frequency generation, stability and good anti-interference performance, and can be widely applied to various electronic products. In addition, the MEMS oscillator also has the advantages of high integratability, programmability, small size, low power consumption and the like.
Drawings
The invention is described in further detail below with reference to the following figures and embodiments:
FIG. 1 is a silicon resonator with wire bond pads that may be bonded to a CMOS integrated circuit;
FIG. 2 is a silicon resonator bondable to a CMOS integrated circuit with through-silicon metal connections;
FIG. 3 is a silicon resonator bondable to a CMOS integrated circuit with thermal control;
FIG. 4 is a silicon resonator that may be fabricated directly on a CMOS integrated circuit;
FIG. 5 is a silicon piezoelectric resonator that can be fabricated directly on a CMOS integrated circuit;
FIG. 6 is a single MEMS silicon piezoelectric oscillator;
fig. 7 is a single MEMS silicon oscillator.
Detailed Description
Example 1
The invention provides an integrated silicon oscillator structure, which is characterized in that: the integrated silicon oscillator structure comprises three resonator structures, an MEMS chip and a CMOS integrated circuit are integrated together through a bonding process, a silicon resonator, an independent MEMS silicon resonator and an integrated circuit chip are directly prepared on the CMOS integrated circuit;
the MEMS resonator is integrated with the CMOS integrated circuit through a bonding process; the structure of the integrated silicon oscillator bonded with the CMOS circuit is divided into three structures:
the first structure is as follows: the silicon resonator with the lead bonding pad and capable of being bonded with the CMOS integrated circuit consists of a cavity wafer 1, a getter 5, a micro-resonator 3, a bonding area 2, the CMOS integrated circuit 6, the lead bonding pad 7 and a substrate 8;
the second structure is as follows: the silicon resonator which is connected with the silicon through hole metal and can be bonded with the CMOS integrated circuit consists of a cavity wafer 1, a getter 5, a micro-resonator 3, a bonding area 2, the CMOS integrated circuit 6, a silicon through hole 7 and a metal bump 8;
a third structure: a silicon resonator bondable to a CMOS integrated circuit with thermal control;
the device comprises a cavity wafer 1, a getter 5, a micro resonator 3, a bonding region 2, a CMOS integrated circuit 6, a silicon through hole 7 and a metal bump 8, a thermal control metal line 12 and a thermal isolation groove 13; the structure can always keep the temperature of the silicon resonator as a constant, and can provide stable output frequency when the external temperature environment changes greatly;
cavity wafer 1: the silicon wafer is composed of silicon, an SOI wafer and a silicon wafer with an epitaxial layer;
getter 2: the material is used as an important material for ensuring the vacuum environment in the cavity wafer and is composed of titanium or zirconium, iron or one or more of alloys or oxides thereof;
the micro resonator 3: the silicon wafer is composed of silicon, belongs to a part of a cavity wafer, and is prepared on the cavity wafer through photoetching, etching and other processes;
bonding region 4: the cavity wafer 1 and the CMOS integrated current wafer 5 are combined into a whole through a bonding process, the bonding area 4 is a connecting part of the cavity wafer 1 and the CMOS integrated current wafer 5, and the bonding process can be one of eutectic bonding, silicon-silicon direct bonding, glass slurry bonding and the like;
CMOS integrated circuit wafer 5: the resonator is made of silicon materials and provides an electrical processing function for the resonator;
wire bonding pad 6: the oscillator is made of metal materials such as Al and Cu and provides external electrical connection for the oscillator;
through silicon via 7: the silicon through hole is used for external electrical connection of the oscillator, and copper metal is filled in the silicon through hole to serve as an electrical medium;
metal bump 8: the through metal is connected with the through silicon via and used for electrical connection, and the through silicon via is composed of copper or other metal materials;
the thermal control metal 12: through the metal deposition process, heat is generated when current is passed through the metal deposition process, and the metal deposition process is used for adjusting the temperature of the silicon resonator, so that the temperature of the silicon resonator is always constant, and more stable frequency output is provided.
Claims (2)
1. An integratable silicon oscillator structure, characterized in that: the integrated silicon oscillator structure comprises three resonator structures, an MEMS chip and a CMOS integrated circuit are integrated together through a bonding process, a silicon resonator, an independent MEMS silicon resonator and an integrated circuit chip are directly prepared on the CMOS integrated circuit;
the MEMS resonator is integrated with the CMOS integrated circuit through a bonding process; the structure of the integrated silicon oscillator bonded with the CMOS circuit is divided into three structures:
the first structure is as follows: the silicon resonator with the lead bonding pad and capable of being bonded with the CMOS integrated circuit consists of a cavity wafer (1), a getter (5), a micro-resonator (3), a bonding area (2), the CMOS integrated circuit wafer (6), the lead bonding pad (4) and a substrate (8);
the second structure is as follows: the silicon resonator which is connected with the silicon through hole metal and can be bonded with the CMOS integrated circuit consists of a cavity wafer (1), a getter (5), a micro-resonator (3), a bonding area (2), the CMOS integrated circuit wafer (6), the silicon through hole (7) and a metal bump (9);
a third structure: a silicon resonator bondable to a CMOS integrated circuit with thermal control;
the device comprises a cavity wafer (1), a getter (5), a micro-resonator (3), a bonding region (2), a CMOS integrated circuit wafer (6), a silicon through hole (7) and a metal bump (9), a thermal control metal line (12) and a thermal isolation groove (13); the structure can always keep the temperature of the silicon resonator as a constant, and can provide stable output frequency when the external temperature environment changes greatly;
cavity wafer (1): the silicon wafer is composed of silicon, an SOI wafer and a silicon wafer with an epitaxial layer;
microresonator (3): the silicon wafer is composed of silicon, belongs to a part of a cavity wafer, and is prepared on the cavity wafer through photoetching and etching processes;
bonding region (2): the cavity wafer (1) and the CMOS integrated circuit wafer (6) are combined into a whole through a bonding process, and the bonding area (2) is a connecting part of the cavity wafer (1) and the CMOS integrated circuit wafer (6); CMOS integrated circuit wafer (6): the resonator is made of silicon materials and provides an electrical processing function for the resonator; wire bonding region (2): the oscillator is made of Al and Cu metal materials and provides external electrical connection for the oscillator; through-silicon-via (7): the silicon through hole is used for external electrical connection of the oscillator, and copper metal is filled in the silicon through hole to serve as an electrical medium; metal bump (9): the through metal is connected with the through silicon via and used for electrical connection, and the through silicon via is made of a metal material; thermal control metal lines (12): through the metal deposition process, heat is generated when current is passed through the metal deposition process, and the metal deposition process is used for adjusting the temperature of the silicon resonator, so that the temperature of the silicon resonator is always constant, and more stable frequency output is provided.
2. An integrable silicon oscillator structure according to claim 1 characterised in that: the position of the resonator and the crystal direction of the wafer (10) need to form an angle of 0-45 degrees.
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| CN201920601608.8U CN211089591U (en) | 2019-04-29 | 2019-04-29 | Integrated silicon oscillator structure |
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| CN201920601608.8U CN211089591U (en) | 2019-04-29 | 2019-04-29 | Integrated silicon oscillator structure |
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