Thermally driven micro-pump buried in a silicon substrate and method for fabricating the same

• US 6,531,417 B2
• Filed: 04/12/2001
• Issued: 03/11/2003
• Est. Priority Date: 12/22/2000
• Status: Expired due to Term

• Current Assignee: Intellectual Discovery Co., Ltd.
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Kim, Yun-Tae, Jun, Chi-Hoon, Choi, Chang-Auck, Jang, Won-Ick
• Primary Examiner(s): Cuneo; Kamand
• Assistant Examiner(s): PERT, EVAN T
• Application Number:
  US09/834,586
• Publication Number:
  US 20020081866A1
• Time in Patent Office: 698 Days
• Field of Search: 216/2 417/52,207 438/800,22
• US Class Current: 438/800
• CPC Class Codes: F04B 19/24 Pumping by heat expansion of pumped fluid
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: F04B 53/1077 Flow resistance valves, e.g. without moving parts

Abstract

The present invention relates to a micro electro mechanical system (MEMS); and, more particularly, to a micro pump used in micro fluid transportation and control and a method for fabricating the same. The micro pump according to the present invention comprises: trenches formed in a silicon substrate in order to form a pumping region including a main pumping region and an auxiliary pumping region; channels formed on both sides of the pumping region; a flow prevention region having backward-flow preventing layers to resist a fluid flow; inlet/outlet regions formed at each of the channels which are disposed on both ends of the pumping region; an outer layer covering the trenches of the silicon substrate and opening portions of the inlet/outlet regions; and a thermal conducting layer formed on the outer layer and over the main pumping region so that a pressure of the fluid in the main pumping region is increased by the thermal conducting layer.

Claims

1. A micro pump comprising:

cavities formed by oxidizing and etching trench walls formed in a silicon substrate in order to form a pumping region including a main pumping region and an auxiliary pumping region;

first channels formed on both sides of the pumping region;

a flow prevention region having backward-flow preventing plates to resist a fluid flow such that the flow of the fluid is directed to a predetermined direction, wherein the backward-flow preventing plates are disposed in the main pumping region and the first channel adjacent to the main pumping region and wherein the backward-flow preventing plates are formed by the silicon substrate in which the cavities formed by oxidizing and etching trench walls are formed;

inlet/outlet regions formed at each of the first channels which are disposed on both ends of the pumping region;

an outer layer covering the trenches of the silicon substrate and opening portions of the inlet/outlet regions; and

a thermal conducting layer formed on the outer layer and over the main pumping region so that a pressure of the fluid in the main pumping region can be increased by the thermal conducting layer.

2. The micro pump as recited in claim 1, further comprising a second channel formed between the main pumping region and the auxiliary pumping region.

3. The micro pump as recited in claim 1, wherein the outer layer is a polysilicon layer.

4. The micro pump as recited in claim 1, wherein the thermal conducting layer is a metal layer or a doped polysilicon layer.

5. The micro pump as recited in claim 1, wherein the backward-flow preventing plates in the flow prevention region are silicon layers between the trenches.

6. The micro pump as recited in claim 1, wherein the main pumping region has a round, rectangular or polygonal shape.

7. A method for forming a micro pump comprising the steps of:

a) forming trenches in a silicon substrate by etching the silicon substrate and forming first and second groups of silicon lines, wherein the silicon lines in the first group have a different aspect ratio from those in the second group and wherein the etched silicon substrate is divided into first and second regions;

b) thermally oxidizing the first and second regions so that the first region is fully filled with a thermal oxide layer and line spaces between the silicon lines in the second region are decreased by said thermal oxide layer;

c) covering the silicon substrate, in which the trenches are formed, with a polysilicon layer;

d) forming inlet/outlet regions by patterning the polysilicon layer and opening the first and second regions;

e) removing the thermal oxide layers in the first and second regions, thereby forming a pumping region of the micro-pump, wherein the pumping region has main and auxiliary pumping regions and wherein the main pumping region includes the first and second silicon lines; and

f) forming a thermal conducting layer on the polysilicon layer.

8. The method as recited in claim 7, wherein step a) comprises the steps of:

forming a silicon nitride layer and a silicon oxide layer on the silicon substrate in this order;

forming an etching mask on the silicon oxide layer in order to define the pumping region; and

etching the silicon nitride layer, the silicon oxide layer and the silicon substrate using the etching mask.

9. The method as recited in claim 7, wherein the line spaces in the first region have a higher width than their silicon line width.

10. The method as recited in claim 7, wherein the silicon lines in the second region have a higher width than those in the first region.

11. The method as recited in claim 7, wherein the thermal oxide layer is removed by a wet-etching process using an HF solution silicon.

12. The method as recited in claim 7, wherein the first silicon lines are disposed in the same direction of a flow of a fluid and wherein the second silicon lines are slanted to prevent a backward flow of the fluid.

13. The method as recited in claim 7, wherein the main pumping region has a round, rectangular or polygonal shape.