CN103941577A - Atom gas cavity device with double reflectors and groove-shaped structure and manufacturing method thereof - Google Patents

Abstract

The invention relates to an atom gas cavity device with double reflectors and a groove-shaped structure and a manufacturing method of the atom gas cavity device. The atom gas cavity device is composed of a cavity body structure defined by a silicon wafer and a glass sheet in a bonding mode, wherein the bottom of the silicon wafer is provided with one reflector, the silicon wafer is provided with a groove, and the other reflector is arranged inside the glass sheet. The cross section of the groove is of an inversed trapezoidal shape structure, and is formed by a 100-type monocrystalline silicon wafer in a silicon anisotropic wet etching mode. The side walls of the groove are 111-type crystal faces of the silicon wafer. The interior of the glass sheet and the bottom of the groove of the silicon wafer are respectively provided with one reflector, and the reflectors are used for reflecting laser many times. The atom gas cavity device can be used for atomic clocks, magnetometers and other systems, laser is reflected many times between the double reflectors, the space length of interaction between laser and atom gas is increased, the signal-to-noise ratio of coherent population trapping signals is increased, and system stability can be improved.

Description

There is atomic gas chamber device and the manufacture method thereof of double mirror and groove type structure

Technical field

The invention belongs to microelectromechanical systems (MEMS) element manufacturing and encapsulation technology field, and atomic physics device technology field, be specifically related to a kind of miniature atomic cavity configuration and manufacture method thereof based on MEMS technique.

Background technology

The degree of accuracy of atomic clock Measuring Time can reach part per billion second even higher, atomic clock is the most artificial clock at present, its correlative study has great importance.CPT(Coherent Population Trapping, coherent layout imprison effect) atomic clock is to utilize double-colored coherent light and atom effect that atom is prepared into coherent state, the atomic frequency source that utilizes CPT signal to realize as microwave frequency discrimination signal.Owing to having the features such as the microminiaturization of being easy to, low-power consumption and high frequency stability, CPT atomic clock is just subject to the attention of research institution of various countries once proposition, and has carried out deep research.

CPT atomic clock is a complicated system, and its core component is exactly atomic gas chamber.Utilize now ripe MEMS fabrication techniques miniature atomic gas cavity, passive-type CPT atomic clock size can be narrowed down to chip-scale.Chip-scale CPT atomic clock can significantly reduce atomic clock volume and power consumption, realizes powered battery, and can be in batches, low-cost production, there is great market in military, civilian every field, therefore become the important development direction of atomic clock.

At present, the atomic gas cavity configuration of the chip-scale CPT atomic clock sandwich structure that normally centre is glass for silicon chip both sides.First on monocrystalline silicon piece, make through hole, then form half cavity configuration with Pyrex glass sheet bonding, after alkaline metal and buffer gas are filled with, then with other a slice Pyrex glass sheet bonding formation hermetically-sealed construction.In the chamber of the alkali metal atom air chamber structure of this structure, light and atom effect optical path length are subject to the restriction of silicon wafer thickness and silicon process technology, be generally 1mm～2mm, further increase thickness difficulty and expensive, therefore light and atomic interaction light path have been limited, the signal to noise ratio (S/N ratio) of CPT signal is lower, has affected the frequency stability of CPT atomic clock.

Summary of the invention

On existing Research foundation, in order further to improve the light path of light and atomic interaction, increase CPT Signal-to-Noise, increase frequency stability, the invention provides a kind of atomic gas chamber device and manufacture method thereof with double mirror and groove type structure.

The atomic gas chamber device with double mirror and groove type structure comprises silicon chip and glass sheet, and a side of described silicon chip is provided with groove, and groove inner bottom part is provided with lower catoptron; One side of described glass sheet is provided with upper reflector; Silicon chip and glass sheet form atomic gas chamber device by bonding, and the upper reflector correspondence on glass sheet is positioned at the groove of silicon chip, and corresponding with lower catoptron.

The xsect of described groove is inverted trapezoidal, and groove is that wet etching forms, and the type of silicon chip is (100) type silicon chip, and the sidewall of groove and the angle of glass sheet that corrosion forms are 54.7 degree.

The width W of described groove is the bottom width of the xsect of inverted trapezoidal, and is more than the twice of silicon wafer thickness H.

The concrete preparation manipulation step of atomic gas chamber device with double mirror and groove type structure is as follows:

1). on silicon chip, make groove

The silicon chip of (100) type of selection, utilizes silicon dioxide to carry out anisotropic wet corrosion as mask layer, on a side of silicon chip, forms the groove that more than 100 xsect is inverted trapezoidal;

2). at making catoptron on glass

Adopt evaporation technology or sputtering technology, utilize hard mask or lift-off technology, on a side of glass sheet, make more than 100 metal film catoptrons, i.e. upper reflector; The bottom of the each groove on silicon chip makes more than 100 metal film catoptrons, descends catoptron;

3). silicon on glass bonding

Carry out silicon on glass bonding, pass into vapour of an alkali metal and buffer gas simultaneously, make silicon chip and glass sheet sealing form atomic gas chamber device;

4). scribing

Taking the groove on silicon chip as unit, whole silicon chip is divided, form 100 above single atomic gas chamber devices.

Described vapour of an alkali metal is rubidium steam or caesium steam, the mixed gas of the nitrogen that described buffer gas is 85%, 10% hydrogen and 5% carbon dioxide.

Useful technique effect of the present invention embodies in the following areas:

1. atomic gas of the present invention chamber device makes to act on light path between laser and alkali metal atom and is mainly determined by the bottom width of groove, therefore can be not limited to silicon wafer thickness, be easy to increase the interaction space length between laser and atomic gas by changing atom cavity size design, the signal to noise ratio (S/N ratio) of coherent layout imprison effect signal is strengthened, be conducive to improve the degree of stability of system;

2. the mainly ripe MEMS technique such as anisotropic wet etching process and silicon-glass anodic bonding based on silicon of the manufacturing technology of atomic gas of the present invention chamber device, therefore cost is low, is easy to realize;

3. the feature based on MEMS batch machining, in the flow of same batch, can complete the manufacture in the atomic gas chamber of different size.

Brief description of the drawings

Fig. 1 is the cross-sectional figure of structure of the present invention.

Fig. 2 is the critical size marked graph of atomic gas of the present invention chamber device.

Fig. 3 is the light path schematic diagram of laser in the device of atomic gas of the present invention chamber.

Fig. 4 is the light path schematic diagram of laser in traditional atomic gas chamber.

In upper figure: the thickness that silicon chip 1, glass sheet 2, atomic gas chamber 3, upper reflector 4, lower catoptron 5, H are silicon chip, W is bottom portion of groove width, the angle between sidewall and glass sheet that α is groove.

Embodiment

Below in conjunction with accompanying drawing, by embodiment, the present invention is further described.

embodiment 1

Referring to Fig. 1 and Fig. 2, the atomic gas chamber device with double mirror and groove type structure comprises silicon chip 1 and glass sheet 2.One side of silicon chip 1 is provided with groove, and the xsect of groove is inverted trapezoidal, and groove inner bottom part is provided with lower catoptron 5; One side of glass sheet 2 is provided with upper reflector 4; Silicon chip 1 and glass sheet 2 form atomic gas chamber 3 devices by bonding, and upper reflector 4 correspondences on glass sheet 2 are positioned at the groove of silicon chip 1, and corresponding with lower catoptron 5.

As shown in Figure 3, the light path of laser in 3 devices of atomic gas chamber mainly determined by the width W of bottom portion of groove, can change light path by the size that regulates W.Referring to Fig. 4, in traditional atomic gas chamber device, laser is directly injected from top, and bottom is penetrated, and light path is determined by the thickness H of silicon chip.

The concrete preparation manipulation step of atomic gas chamber device with double mirror and groove type structure is as follows:

1. choose the N(100 that thickness is 0.5～1mm) silicon chip 1 of type, utilize silicon dioxide to make mask, utilize potassium hydroxide solution to carry out anisotropic wet etching process, on silicon chip 1, form the groove that 200 xsects are inverted trapezoidal, the sidewall of groove is that { 111} crystal face, the bottom width of groove is 3mm.The temperature of potassium hydroxide corrosion is 60 DEG C;

2. adopt evaporation technology, utilize lift-off technology, on a side of glass sheet 2, make 200 metal film catoptrons, i.e. upper reflector 4; Bottom at each groove of silicon chip 1 makes 200 metal film catoptrons, descends catoptron 5;

3. carry out silicon on glass bonding, pass into rubidium steam and buffer gas simultaneously, make silicon chip 1 and glass sheet 2 sealings form atomic gas chamber device; Buffer gas is the mixed gas of the carbon dioxide composition of 85% nitrogen, 10% hydrogen and 5%.The process conditions of anode linkage are: 400 DEG C of temperature, voltage 600V;

4. scribing

Taking the groove on silicon chip 1 as unit, whole silicon chip 1 is divided, form 200 single atomic gas chamber 3 devices.

embodiment 2

As shown in Figure 1, specific embodiments is as follows for the structure in the atomic gas chamber of the present embodiment:

1. choose the P(100 that thickness is 0.5～1mm) silicon chip 1 of type, utilize silicon nitride to make mask, carry out anisotropic wet corrosion by TMAH solution, on silicon chip 1, forming xsect is 150 grooves of inverted trapezoidal, the sidewall of groove is that { 111} crystal face, the transverse width of through hole is 5mm.The temperature of TMAH solution corrosion is 80 DEG C;

2. adopt sputtering technology, utilize hard mask technique, on a side of glass sheet 2, make respectively 150 metal film catoptrons, i.e. upper reflector 4; Bottom at each groove of silicon chip 1 makes 150 metal film catoptrons, descends catoptron 5;

3. carry out silicon on glass bonding, pass into caesium steam and buffer gas simultaneously, make silicon chip 1 and glass sheet 2 form the atomic gas chamber device of sealing; Buffer gas is the mixed gas of the carbon dioxide composition of 85% nitrogen, 10% hydrogen and 5%, and the process conditions of anode linkage are: 400 DEG C of temperature, voltage 600V;

4. scribing, taking the groove on silicon chip 1 as unit, divides whole silicon chip 1, forms 150 single atomic gas chamber 3 devices.

Claims (5)

1. the atomic gas chamber device with double mirror and groove type structure, is characterized in that: comprise silicon chip and glass sheet, a side of described silicon chip is provided with groove, and groove inner bottom part is provided with lower catoptron; One side of described glass sheet is provided with upper reflector; Silicon chip and glass sheet form atomic gas chamber device by bonding, and the upper reflector correspondence on glass sheet is positioned at the groove of silicon chip, and corresponding with lower catoptron.

2. the atomic gas chamber device with double mirror and groove type structure as claimed in claim 1, it is characterized in that: the xsect of described groove is inverted trapezoidal, groove is that wet etching forms, the type of silicon chip is (100) type silicon chip, and the sidewall of groove and the angle of glass sheet that corrosion forms are 54.7 degree.

3. the atomic gas chamber device with double mirror and groove type structure as claimed in claim 2, is characterized in that: the bottom width of the xsect that the width W of described groove is inverted trapezoidal, and be more than the twice of silicon wafer thickness H.

4. the manufacture method of the preparation atomic gas chamber device with double mirror and groove type structure as claimed in claim 1, is characterized in that concrete preparation manipulation step is as follows:

1). on silicon chip, make groove

The silicon chip of (100) type of selection, utilizes silicon dioxide to carry out anisotropic wet corrosion as mask layer, on a side of silicon chip, forms the groove that more than 100 xsect is inverted trapezoidal;

2). at making catoptron on glass

Adopt evaporation technology or sputtering technology, utilize hard mask or lift-off technology, on a side of glass sheet, make more than 100 metal film catoptrons, i.e. upper reflector; The bottom of the each groove on silicon chip makes more than 100 metal film catoptrons, descends catoptron;

3). silicon on glass bonding

Carry out silicon on glass bonding, pass into vapour of an alkali metal and buffer gas simultaneously, make silicon chip and glass sheet sealing form atomic gas chamber device;

4). scribing

Taking the groove on silicon chip as unit, whole silicon chip is divided, form 100 above single atomic gas chamber devices.

5. manufacture method as claimed in claim 4, is characterized in that: described in step 3), vapour of an alkali metal is rubidium steam or caesium steam, the mixed gas of the nitrogen that described buffer gas is 85%, 10% hydrogen and 5% carbon dioxide.