WO2011053110A2

WO2011053110A2 - An integrated packaged environmental sensor and roic and a method of fabricating the same

Info

Publication number: WO2011053110A2
Application number: PCT/MY2010/000182
Authority: WO
Inventors: Mohd Ismahadi Syono; Daniel Chia Sheng Bien; Hing Wah Lee
Original assignee: Mimos Berhad
Priority date: 2009-10-27
Filing date: 2010-09-30
Publication date: 2011-05-05
Also published as: MY147335A; WO2011053108A1; WO2011053110A3

Abstract

An integrated packaged microchip (100) including at least one environmental sensor (104) and at least one Read-Out Integrated Chip (ROIC) (102) is provided, characterized in that, the integrated packaged microchip (100) further includes an etched opening (108) of the environmental sensor (104) exposed to a sensable environment, using at least one layer of glass wafer (101,106) and at least one layer of silicon wafer (107).

Description

AN INTEGRATED PACKAGED ENVIRONMENTAL SENSOR AND ROIC AND A METHOD OF FABRICATING THE SAME

FIELD OF INVENTION

The present invention relates to a method of fabricating an environmental sensor integrated with a Read-Out Integrated Chip (ROIC) on one integrated microchip package. BACKGROUND OF INVENTION

Sensors, especially chemical sensors are used in different environments, sometimes with harsh conditions such as oxidation ponds and chemical tanks. In aquatic and, agricultural areas, chemical sensors are used to detect dissolved oxygen, pH, ammonia, fertilizer compunds and other substances as such. This sort of environment demands an adequate protection for the sensors being deployed.

Another major problem with chemical sensors is that unique sensors are required for; sensing different types of chemicals which differ mainly in the sensing membrane that is being used. Combination of various types of sensors then becomes a time consuming and tedious process.

Future applications for long term monitoring in harsh environments require sensors to be on a single platform together with any other supporting circuitry. Isolated components would result in lower signal integrity and higher power consumption. · _. ^· . ; · 2 .. - . ^■ :^■ _. ·.,

US 2003049865 describes microchip devices which include a substrate having a . plurality of reservoirs containing a secondary device, a reacting component, or a combination thereof. However, the document does not describe a solution for solving the problem of testing process being time consuming. Test time for chemical sensors is long and tedious. Often, sensors need to be packaged before testing. Unfortunately, lead time for packaging itself is long and could contribute to sensor failure;

Chemical sensors are also costly to produce and test. These sensors often require expensive standard solutions for testing and are done under controlled environments. .·„ Sensor packaging is also often done individually causing low reproducibility.

Therefore, there is a need for a method or system to allow for environmental sensors and supporting circuitry to operate from one substrate or platform to simplify the process.

SUMMARY OF INVENTION

Accordingly there is provided an integrated packaged microchip including at least one environmental sensor and at least one Read-Out Integrated Chip (ROIC), characterized in that, the integrated packaged microchip further includes an etched opening of the environmental sensor exposed to a sensable environment, using at least one layer of glass wafer and at least one layer of silicon wafer- There is also provided a method of fabricating at least one environmental sensor, integrated with at least one Read-Out Integrated Chip (ROIC), characterized in that, the method includes the steps of establishing metal contacts on a first glass wafer, attaching the at least one environmental sensor and at least one (ROIC) die to the first glass wafer, capping the first glass wafer with a second glass wafer, dispensing analyte on the at least one environmental sensor and the ROIC and dicing the integrated environmental sensor and ROIC.

There is also provided a method of fabricating at least one environmental sensor integrated with at least one Read-Out Integrated Chip (ROIC), wherein an etched opening of the environmental sensor is exposed to a sensable environment, characterized in that, the method includes the steps of ariodically bonding a first glass wafer to a silicon wafer, etching the first layer of glass wafer to create a tapered profile, patterning with metal lines on the first glass wafer, etching the silicon wafer following the pattern on the first glass wafer, attaching the environmental sensor and the ROIC to a plurality of metal contacts on the first glass wafer, wherein the plurality of metal contacts are connected to the metal lines, attaching the environmental sensor to the first glass wafer by anodic bonding of sensing area on top of the etched opening exposed to the environment, bonding a second glass wafer to the first glass wafer by enclosing the ROIC and partially enclosing the environmental sensor by following the . patterned metal lines and dicing the integrated environmental sensor and ROIG packaged microchip.

The present invention consists of several novel features and a combination of parts hereinafter, fully described and illustrated in the accompanying description and" drawings, it being understood that various changes in the details may be made without departing from the scope of the invention or sacrificing any of the advantages of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute part of this specification and include an exemplary or preferred embodiment of the invention, which may be embodied in various forms. It should be understood, however, the disclosed preferred embodiments are merely exemplary of the invention. Therefore, the figures (not to scale) disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and for teaching one skilled in the art of the invention.

Figure 1 shows an overall step by step view of an embodiment of a method of fabrication of an integrated environmental sensor and ROIC;

Figure 2 shows an overall flowchart of an embodiment of a method of fabrication of an integrated environmental sensor and ROIC;

Figure 3 shows a second embodiment of a method of fabrication of an integrated environmental sensor and ROIC up to a first glass wafer; and Figure 4 shows a second embodiment of a method of fabrication of an integrated environmental sensor and ROIC from the second glass wafer up to dicing the integrated packaged microchip.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method of fabricating an environmental sensor integrated with a Read-Out Integrated Chip (ROIC) on one integrated microchip package. Hereinafter, this specification will describe the present invention according to the preferred embodiments of the present invention. However, it is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the scope of the appended claims.

The following detailed description of the preferred embodiments will now be described in accordance with the attached drawings, either individually or in combination. Figure 1 shows an embodiment of a method of fabricating an integrated packaged microchip (100) including at least one environmental sensor (104) and at least one Read-Out Integrated Chip (ROIC) (102). The integrated packaged microchip (100) further includes an etched opening (108) of the environmental sensor (104) exposed to a sensable environment, using at least one layer of glass wafer (101) and at least one layer of silicon wafer. A first glass wafer (101) is patterned and etched through to provide access for liquid or gas to the environmental sensor (104). Metal lines are then created on a polished side of the first glass wafer (101) in order to provide contact to the environmental sensor (104) and ROIC (102). The environmental sensor (104) and the ROIC (102) are silicon based, wherein the environmental sensor (104) and the ROIC (102) are then attached to a plurality of metal contacts (8) on the first glass wafer. (101). A second glass wafer (106) which includes metal lines is bonded to the first glass layer (101) for capping. Since both the environmental sensor (104) cavity and the metal lines are on a same plane, analyte can be disperised on the environmental . sensor (104) for integrated testing. Ah example of an environmental sensor (104) is a chemical sensor. Figure 2 shows an overall flow chart of the method of fabrication as described above.

A second embodiment of the method of fabrication is by beginning with a first glass wafer (101) patterned with metal lines, as seen in Figure 3. An opening (108) is etched onto the first glass wafer (101 ). Both the environmental sensor (104) and the ROIC (102) are attached onto the first glass wafer (101 ) by anodic bonding with the environmental sensor's (104) sensing area (9), as seen in Figure 3 as well. The sensing area (9) is positioned exactly above the etched opening (108). A plurality of metal contacts (8), as seen in Figure 3, are connected to metal lines as seen in Figure 1. An example of the plurality of metal contacts that can be used is bondpads as used in flip chip packaging. Glass material used in the first glass wafer (101) and the second glass wafer (107) is selected from glass with a relatively high softening temperature, . such as Borofloat 33®or Pyrex® #7740. However, the material used is not restricted to the examples described herein, as any material seen fit may be used.

Further as seen in Figure 3, polishing of a silicon wafer (107) is done or etched back in potassium hydroxide wet etch ant if required. The first glass wafer (101 ) is dry etched by a predetermined distance such as 0.6 micrometer (μιτι) to create a tapered profile The first glass wafer (101 ) is then patterned by metal lines such as gold and chromium, or platinum and titanium. Next, the silicon wafer (107) is patterned and etched by using deep reactive ion etching (DRIE) process. The first glass wafer (101 ) is further etched in a solution of 48% of a ratio of hydrofluoric acid (HF): hydrochloric acid (HCI): nitric acid (HN03) which is 50:5:1 for a smooth surface. The ROIC (102) and the environmental sensor (104) are attached on the first glass wafer (101) by a plurality of metal contacts (8) that are connected to the metal lines. The environmental sensor (104) is attached to the first glass wafer (101) by anodic bonding of sensing area (9) on top of the etched opening (108) exposed to the environment The attaching process is done by flip chip bonding where an aluminum bondpad is connected to a gold bondpad by several methods such as thermosonic or thermocompression bonding or soldering.

Figure 4 shows the second glass wafer (106) being attached to the first glass wafer (101). The second glass wafer (106) is of a predetermined thickness such as, 1.5 millimetres (1.5 mm). Analyte such as, gold and chromium or platinum and titanium are deposited on the second glass wafer (106) and patterned accordingly. The second glass wafer (106) is wet etched in a composition of HF: HCI: HN03 by a predetermined thickness such as 800 m. The patterned side of the second glass wafer (106) is bonded to the patterned side of the first glass wafer (101), by a gold bondpad to gold bondpad connection using thermosonic or thermocompression fusion or anodic bonding.

Finally, the integrated packaged microchip (100) which includes at least one environmental sensor (104) and at least one Read-Out Integrated Chip (ROIC) (102), which further includes an etched opening (108) of the environmental sensor (104) exposed to a sensable environment is diced to produce a final packaged microchip

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The methods described are intended to produce an integrated solution for various, environmental sensors to solve the problem of tediousness and difficulties in using various types of sensors. The methods described above provide a method to integrate all sensors on one substrate together with an ROIC which reduces test time, packaging lead time and manufacturing cost. The embodiment of the present invention makes this possible by using an integrated chip wafer level and packaged testing. This integration improves signal integrity and lowers power consumption of the invention/ The method also allows the environmental sensors and ROIC to be chemically inert, waterproof and hermetic, electrically insulated while being robust, stable and readily integrable to silicon as well as cheap to be produced.

Testing for the integrated packaged microchip (100) can be automated to shorten lead time and this reduces chances of sensor failure rates. Furthermore, as the method of fabrication is similar to integrated chip fabrication methods, the integrated packaged microchip (100) can be batch processed because of high reproducibility of process.

This invention is adapted for use with a variety of environmental sensors. The disclosed invention is suitable, but not restricted to, for use in harsh environment.

Claims

1. An integrated packaged microchip (100) including at least one environmental sensor. (104) and at least one Read-Out Integrated Chip (ROIC) (102), characterized in that, the integrated packaged microchip (100) further includes an etched opening ( 08) of the environmental sensor (104) exposed to a sensable environment, using at least one layer of glass wafer (101 ,106) and at least one layer of silicon wafer (107).

2. A method of fabricating at least one environmental sensor (104) integrated with at least one Read-Out Integrated Chip (ROIC) (102), characterized in that, the method includes the steps of:

i. establishing metal contacts on a first glass wafer (101);

ii. attaching the at least one environmental sensor (104) and at least one (ROIC) (102) die to the first glass wafer (101);

iii. capping the first glass wafer (101) with a second glass wafer (106);

iv. dispensing analyte on the at least one environmental sensor (104) and the ROIC (102); and

v. dicing the integrated environmental sensor (104) and ROIC (102).

3. A method of fabricating at least one environmental sensor (104) integrated with at least one Read-Out Integrated Chip (ROIC) (102), wherein an etched opening ( 08) of the environmental sensor (104) is exposed to a sensable environment, characterized in that, the method includes the steps of:

i. anodically bonding a first glass wafer (101 ) to a silicon wafer (107);

ii. etching the first layer of glass wafer (101 ) to create a tapered profile;

iii. patterning with metal lines on the first glass wafer (101 ); iv. etching the silicon wafer (107) following the pattern on the first glass wafer (101 ); v. attaching the environmental sensor (104) and the ROIC (102) to a plurality of metal contacts (8) on the first glass wafer (101 ), wherein the plurality of metal contacts (8) are connected to the metal lines;

vi. attaching the environmental sensor (104) to the first glass wafer (101 ) by anodic bonding of sensing area (9) on top of the etched opening (108) exposed to the environment;

vii. bonding a second glass wafer (106) to the first glass wafer (101 ) by enclosing the ROIC (102) and partially enclosing the environmental sensor (104) by following the patterned metal lines; and

viii. dicing the integrated environmental sensor (104) and ROIC (102) packaged

microchip (100).

4. The method as claimed in claim 3, wherein the silicon wafer (107) is polished in potassium hydroxide wet etchant.

5. The method as claimed in claim 2 and 3, wherein the first glass wafer (101 ) and second glass wafer (106) are constructed of glass with a high temperature softening point.

6. The method as claimed in 2 and 3, wherein the metal lines are made up of analyte substance.