VAPOR CELL COMPRISING ELECTRO-OPTIC FUNCTION FOR CHIP-SCALE ATOMIC CLOCK, AND METHOD FOR MANUFACTURING SEALED CONTAINER FOR CHIPSCALE INSTRUMENT

• US 20180212612A1
• Filed: 07/29/2016
• Published: 07/26/2018
• Est. Priority Date: 07/30/2015
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: PARK, Jong Cheol, KIM, Hee Yeoun, YANG, Chung Mo, KIM, Tae Hyun
• Granted Patent: US 10,447,286 B2
• Time in Patent Office: Days
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/031 Anodic bondings
• CPC Class Codes: G04F 5/14 using atomic clocks
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H03L 1/04 Constructional details for maintaining temperature constant
• CPC Class Codes: H03L 7/26 using energy levels of molecules, atoms, or subatomic particles as a frequency reference

Abstract

According to the present invention, since a silicon body itself supporting first and second glass substrates also has a role of an electric heating device, the temperature of the inside of a through-part can be maintained to be constant. In addition, since it is unnecessary to comprise a separate electric heating device such as a heater or to form an additional heating pattern in order to control the temperature of the inside of the through-part, a process for manufacturing a vapor cell can be simplified. According to the present invention, only a reactive material in a gas state and a buffer gas can be injected into a sealed container without the intervention of other materials, and the size of the sealed container can be reduced since it is unnecessary to prepare e separate space for mounting a pill of the reaction material in a vapor cell region itself.

Claims

1. A vapor cell having an electro-optical function for a chip-scale atomic clock, the vapor cell comprising:

a silicon body having a through-part which is a space where a reactive substance is contained;

a first glass substrate which is disposed on one surface of the silicon body and closes one side of the through-part; and

a second glass substrate which is disposed on the other surface of the silicon body and closes the other side of the through-part,

wherein a voltage is applied to the silicon body to control a temperature inside the through-part.

2. The vapor cell according to claim 1, wherein the through-part is positioned at a center of the silicon body.

3. The vapor cell according to claim 1, wherein a predetermined amount of a p-type or n-type impurity is implanted into the silicon body.

4. The vapor cell according to claim 1, wherein the shape of the silicon body is a 2n (n is an integer of 3 or more) polygonal or cylindrical column.

5. The vapor cell according to claim 1, further comprising:

a first concave portion which is provided to the first glass substrate and continuously connected to one side of the through-part; and

a collimator which is disposed in the first concave portion and converts the light incident on the first glass substrate into a parallel light.

6. The vapor cell according to claim 1, further comprising:

a first concave portion which is provided to the first glass substrate and continuously connected to one side of the through-part; and

a second concave portion which is provided to the second glass substrate and continuously connected to the other side of the through-part.

7. The vapor cell according to claim 1, further comprising:

a metal terminal for wiring to external conductors at both opposing ends of the silicon body relative to the through-part.

8. A method for manufacturing a sealed container for a chip-scale device, the method comprising the steps of:

(A) forming a silicon body on and between opposite ends of a lower glass substrate so as to be partitioned into a vapor cell region and a dispensing region on the lower glass substrate, and providing a channel through which a reactive substance can be communicated between the vapor cell region and the dispensing region;

(B) injecting a buffer gas into the vapor cell region and accommodating a reactive substance pill in the dispensing region;

(C) sealing the buffer gas from the outside by bonding an upper glass substrate to an upper portion of the silicon body formed at the opposite ends;

(D) activating the reactive substance pill to inject the reactive substance of a gaseous state through the channel into the vapor cell region;

(E) locally heating a portion of the upper glass substrate which corresponds to the channel to close the channel; and

(F) dicing the silicon body formed between the opposite ends, the lower glass substrate and the upper glass substrate adjacent thereto in a height direction of the silicon body formed between the opposite ends.

9. The method according to claim 8, wherein the channel is provided by making the height of the silicon body formed on the opposite ends of the lower glass substrate equal and forming the height of the silicon body formed between the opposite ends is lower than the height of the silicon body formed on the opposite ends.

10. The method according to claim 8, wherein the channel is provided by making the height of the silicon body formed on and between the opposite ends of the lower glass substrate equal and forming a concave portion on an upper surface of the silicon body formed between the opposite ends of the lower glass substrate.

11. The method according to claim 8, wherein the dispensing region is one, and the vapor cell region is plural.

12. The method according to claim 8, further comprising:

polishing a surface of the upper glass substrate after the step (E).

13. A method for manufacturing a sealed container for a chip-scale device, the method comprising the steps of:

(a) forming a silicon body having an equal height on and between opposite ends of a lower glass substrate so as to be partitioned into a vapor cell region and a dispensing region on the lower glass substrate, and forming a sub silicon body which has a height lower than a height of the silicon body adjacent to the silicon body formed on the opposite ends;

(b) depositing a bonding portion on the sub silicon body such that a total height including the height of the sub silicon body and a height of the bonding portion is higher than the height of the silicon body;

(c) injecting a buffer gas into the vapor cell region and accommodating a reactive substance pill in the dispensing region;

(d) sealing the buffer gas from the outside by bonding an upper glass substrate to an upper portion of the bonding portion;

(e) activating the reactive substance pill to inject the reactive substance of a gaseous state into the vapor cell region;

(f) melting the bonding portion to bond the upper glass substrate to an upper portion of the silicon body; and

(g) dicing the silicon body formed between the opposite ends, the lower glass substrate and the upper glass substrate adjacent thereto in a height direction of the silicon body formed between the opposite ends.

14. The method according to claim 13, wherein the bonding portion is a metal mixture having a melting point lower than melting points of the silicon body and the sub silicon body, and

the step (f) is carried out at a higher temperature than the step (d).

15. The method according to claim 13, wherein the bonding portion is a glass frit having a glass transition temperature lower than melting points of the silicon body and the sub silicon body, and

the step (f) is carried out at a higher temperature than the step (d).

16. The method according to claim 13, wherein a guiding portion is further provided, and

when the upper glass substrate is bonded to the upper portion of the silicon body in the step (f), the bonding portion is melted and drawn into the guiding portion.

17. The method according to claim 13, wherein the dispensing region is one, and the vapor cell region is a plural.