JP4271741B2 - Semiconductor parts - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates generally to semiconductor devices, and more particularly to sensors.
[0002]
[Background Art and Problems to be Solved by the Invention]
Sensor implementation is a laborious, time consuming and expensive process. For chemical sensors, the mounting process includes cutting the semiconductor substrate into individual chemical sensor chips. The individual chemical sensor chips are then separately glued and assembled into a large metal package, referred to in the art as a T39 package or T05 package. An example of a T05 package is described in US Pat. No. 4,768,070 issued August 30, 1988 to Takizawa et al. This process of mounting the piece components is time consuming and cumbersome and requires careful handling of individual chemical sensor chips that can become contaminated or physically damaged during the mounting process.
[0003]
Accordingly, there is a need for a sensor that is mounted using a batch processing technique that improves throughput and reduces sensor creation and mounting cycle time. Wafer level batch mounting technology produces smaller mounted sensors, protecting each sensor chip from contamination and physical damage during subsequent processing.
[0004]
【Example】
For a more detailed description, referring to the drawings, FIG. 1 is a cross-sectional view of an embodiment of a sensor 10. The sensor 10 is a semiconductor component including a substrate 11. The substrate 11 has a surface 19 that faces the surface 20, and is usually composed of a semiconductor material such as silicon, a III-V group compound semiconductor, or a II-VI group compound semiconductor. It will be appreciated that a plurality of sensors can be created on the substrate 11. For example, FIG. 1 shows a portion of sensors 34, 35 adjacent to sensor 10 on substrate 11. FIG. 1 also shows straight lines 36 and 37 that function as drawn lines separating the sensor 10 from the sensors 34 and 35, respectively.
[0005]
An insulating layer 32 is provided on the surface 19 of the substrate 11. Insulating layer 32 is preferably a dielectric material, such as silicon oxide or silicon nitride, and can be deposited on substrate 11 using methods well known in the art.
[0006]
The substrate 11 has an optional recess 12 formed in a portion of the surface 20 to facilitate thermal diffusion of the sensor 10 described below. The recess 12 extends from the surface 20 toward the surface 19 and can expose a portion of the insulating layer 32. In order to ensure a manufacturable process of the sensor 10, the recess 12 is preferably etched into the surface 20 using an anisotropic etchant that etches along a particular crystal plane of the substrate 11. The anisotropic etchant should not etch the insulating layer 32 more than the substrate 11. Examples of anisotropic etchants suitable for use with single crystal silicon substrates include, but are not limited to, potassium hydroxide, ammonium hydroxide, cesium hydroxide, hydrazine, ethylenediamine / pyrocatechin, and tetramethylammonium hydroxide. Not.
[0007]
The sensor 10 includes a sensing element 14 that is supported by the insulating layer 32 and the substrate 11 and is on the recess 12. When the sensor 10 is a chemical sensor, the sensing element 14 is typically a resistance that changes its resistance when exposed to a particular liquid or gas (not shown). At elevated operating temperatures, the resistivity of sensing element 14 is typically about 1 kilohm to 50 megaohms. As is well known in the chemical sensor art, the presence of a particular liquid or gas is converted by the sensor from a chemical reaction to an electrical signal. For example, a control circuit (not shown) can detect a change in the specific resistance of the sensing element 14 by measuring a change in current or voltage drop across the sensing element 14. The control circuitry can be on a different substrate or can be created in the substrate 11 to create an integrated chemical sensor system.
[0008]
The sensing element 14 is placed or formed on the insulating layer 32 and the surface 19 of the substrate 11 using methods well known in the art. When the sensor 10 is a chemical sensor, the sensing element 14 is configured by a thin film having a chemical sensitivity with conductivity such as a metal oxide, a transition metal, or a noble metal. For example, the sensing element 14 can be made of tin oxide, zinc oxide, titanium oxide, an alloy of platinum and gold, or the like. Different sensing elements 14 can be used to detect or monitor different liquids or gases. It should be understood that the material used for sensing element 14 can be doped to further increase the chemical sensitivity and selectivity of sensing element 14 and sensor 10.
[0009]
The sensing element 14 can also be heated by an optional heating element 13 to help cause a chemical reaction between the sensing element 14 and the desired liquid or gas. The heating element 13 is formed using a method well known to those skilled in the art. For example, the heating element 13 can also be made of polycrystalline silicon or a metal such as platinum or gold.
[0010]
As shown in FIG. 1, the heating element 13 is above the recess 12 and below the sensing element 14 in the insulating layer 32. It should be understood that the heating element 13 can be placed on a substrate other than the substrate 11. However, both the heating element 13 and the sensing element 14 are preferably placed on the substrate 11 for efficient heating and space saving. The recess 12 in the substrate 11 aids in thermal diffusion or cooling of the heating element 13 and the sensor 10.
[0011]
Coupling lines 15 and 16 electrically couple features 17 and 18 to sensing element 14, respectively. The coupling lines 15 and 16 are made of a conductive material such as silicide or metal. The coupling lines 15 and 16 are formed on the insulating layer 32 and the surface 19 of the substrate 11 using methods well known in the art.
[0012]
The features 17 and 18 are in electrical contact with the sensing element 14. For example, assembly wire bond wiring can be coupled to features 17 and 18 to form bonding pads. The features 17 and 18 are typically made of a metal such as gold or copper (but not limited to), and are formed on the insulating layer 32 and the surface 19 of the substrate 11 by a sputtering method, an electroplating method, Deposited using chemical vapor deposition or vapor deposition.
[0013]
The adhesive 21 is on the bonding lines 15, 16, on the insulating layer 32, and on the surface 19 of the substrate 11, preferably spatially away from the sensing element 14 to avoid contamination of the sensing element 14. Placed apart. The adhesive 21 can be any organic or inorganic adhesive material such as solder preform, silk screen epoxy or frit glass. When a conductive adhesive is used as the adhesive 21, a separation layer (not shown) electrically separates the bonding wires 15 and 16 from the adhesive 21.
[0014]
The adhesive 21 covers or mounts the sensor 10 by bonding or electrically bonding the insulating layer 32 and the mesh, screen or filter 22. As a result, the adhesive 21, the insulating layer 32, the substrate 11 and the filter 22 form the cavity 31. The capacity of the cavity 31 can be controlled by the thickness or height of the adhesive 21. As shown in FIG. 1, the sensing element 14 is located in the cavity 31, and the features 17 and 18 are located outside the cavity 31.
[0015]
The filter 22 is above the insulating layer 32 and the cavity 31 and filters, shields or prevents unwanted particles or chemicals from entering the cavity 31. The filter 22 has a surface 23, a facing surface 24, contact openings 25 and 30, and filtering holes 26, 27, 28, and 29 that function as a filtering mechanism for the filter 22. This will be described in detail later.
[0016]
The filter 22 is preferably placed spatially away from the sensing element 14 to avoid contamination or damage of the sensing element 14. The filter 22 must have an appropriate thickness that is substantially rigid. This is to prevent elastic deformation that may cause contact with the detection element 14 or damage to the detection element 14.
[0017]
A wide range of materials as described below can be used for the filter 22. However, many of the materials used for the filter 22 will degas chemicals when the operating temperature of the sensor 10 is increased. The filter 22 preferably ensures an accurate chemical response to the environment of the sensor 10 without degassing the chemicals even when the operating temperature rises. However, even if the filter 22 evacuates the chemical substance, the filter 22 should not allow the chemical substance that can be detected by the sensing element 14 to be evacuated, so that the sensor 10 can perform accurate environmental monitoring. . Similarly, the adhesive 21, insulating layer 32, substrate 11, bond lines 15, 16 and features 17, 18 should not degas chemicals that can be detected by the sensing element 14 at the operating temperature of the sensor 10. .
[0018]
The filter 22 can be composed of a non-porous material or a porous or breathable material. Possible suitable non-porous materials include, but are not limited to, conventional single crystal silicon substrates, III-V compound semiconductor substrates, and II-VI compound semiconductor substrates. Possible suitable porous or breathable materials include porous silicon substrates, polymer films, porous ceramics, glass, charcoal filters, thermosetting resins, alumina, polyimide, silica and quartz, It is not limited to these.
[0019]
If the filter 22 is composed of a porous or breathable material, another filtering mechanism is provided that is not present when the filter 22 is composed of a non-porous material. A particular liquid or gas can penetrate a particular porous or breathable material and can enter the cavity 31 without passing through the filter holes 26, 27, 28, 29 of the filter 22. As such, a porous or breathable material can extend or enhance the filtering function of the filter 22 to improve the chemical sensitivity and selectivity of the sensor 10 over that of a non-porous material.
[0020]
Each porous or breathable material has a different pore size, which can be used to filter particles, chemicals or molecules of different sizes. Porous or breathable materials can be chemically active. As an example of a chemically active breathable material, a layer of metallophthalocyanine polymer can be used in the filter 22 to prevent nitrous oxide from passing through the cavity 31. As an example of a porous material, a compression charcoal filter can be used for filter 22 to filter hydrocarbons and prevent entry into cavity 31. Furthermore, the polyimide layer can be used for the filter 22 to prevent moisture or water vapor from entering the cavity 31.
[0021]
Returning to the description of the contact openings 25 and 30 in the filter 22, the contact openings 25 and 30 are located above the features 17 and 18, respectively, to serve as access paths for these features. When features 17 and 18 function as bonding pads, contact openings 25 and 30 each have a size of about 50 to 1,000 microns, and the assembled wire bond wiring passes through contact openings 25 and 30. The contact features 17 and 18 respectively. Contact openings 25 and 30 can also expose die isolation regions shown as straight lines 36 and 37 in FIG.
[0022]
The filter holes 26, 27, 28 and 29 of the filter 22 are located above the cavity 31 and function as a filter mechanism of the filter 22. Even if the filter 22 can have a single hole above the cavity 31, the filter 22 will still have sufficient gas or liquid flow in and out of the cavity 31 while maintaining sufficient filtering function as described below. It is preferable to have a plurality of holes so that it is possible. The filtering holes 26, 27, 28, 29 preferably have a diameter that is smaller than the diameter of the contact openings 25, 30, respectively, so that unwanted particles do not enter the cavity 31. Thereby, the filter 22 protects the sensing element 14 from physical damage and contamination during substrate dicing, other assembly processes, and operation of the sensor 10.
[0023]
If desired, the filtering holes 26, 27, 28, 29 each have a diameter on the order of a few angstroms to a few microns, so that larger sized molecules or chemicals enter the cavity 31 and the sensing element 14 and It can prevent chemical reaction. Thus, the filter 22 is also used as a chemical filter for improving the chemical selectivity and sensitivity of the sensor 10. For example, suppose sensor 10 monitors only small hydrocarbon molecules, and sensing element 14 causes a chemical reaction with small hydrocarbon molecules, larger protein molecules, and even larger deoxyribonucleic acid molecules (DNA). In this case, assuming that the filter holes 26, 27, 28, 29 each have a diameter of about several angstroms, small hydrocarbon molecules pass through the filter holes 26, 27, 28, 29 and react with the sensing element 14. However, larger protein molecules and DNA molecules cannot pass through the filter holes 26, 27, 28, and 29, and cannot react with the sensing element 14. Therefore, in this example, the chemical selectivity of the sensor 10 is improved.
[0024]
The filtering holes 26, 27, 28, 29 and the contact openings 25, 30 are ultra-precision processed in the filter 22 before the filter 22 and the substrate 11 are coupled. Filter holes 26, 27, 28, 29 and contact openings 25, 30 can be formed using a wide variety of different chemical and physical methods. For example, the filter holes 26, 27, 28, 29 and the contact openings 25, 30 can be formed in the filter 22 using reactive ion etching or mechanical drilling techniques. As another example, if the filter 22 is composed of a non-porous single crystal silicon substrate having a thickness of about 100 to 500 microns, an anisotropic etchant similar to that used for the recess 12 in the substrate 11 is used. It can also be used to etch the filter holes 26, 27, 28, 29 and the contact openings 25, 30.
[0025]
The filtering holes 26, 27, 28, 29 and the contact openings 25, 30 can be etched from the surface 23, from the surface 24, or from both surfaces 23, 24. As shown in FIG. 1, the contact openings 25, 30 and the filtering holes 26 are etched from the surface 23, the holes 27 are etched from the surface 24, and the holes 28, 29 are etched from the surfaces 23, 24. When holes are etched from both surfaces 23, 24, more or more dense holes can be provided compared to when the holes are etched only from one surface of the filter 22.
[0026]
With continued reference to FIG. 2, a partial cross-sectional view of an alternative embodiment of sensor 10 of FIG. The sensor 40 of FIG. 2 is similar to the sensor 10 of FIG. 1, and the same reference numerals are used in FIGS. 1 and 2 to indicate the same elements. In FIG. 2, the cavity 44 is formed by bonding the insulating layer 32 and the filter 45 using the adhesive 21. Cavity 44 and filter 45 are similar in purpose to cavity 31 and filter 22 of FIG. 1, respectively.
[0027]
The filter 45 is constituted by a layer 43 on the support layer 41. The support layer 41 is similar in composition to the filter 22 of FIG. The support layer 41 has a plurality of holes 42 that are covered with a layer 43. These holes are similar in purpose to the filtering holes 26, 27, 28, 29 of the filter 22 of FIG.
[0028]
Layer 43 is comprised of a porous or breathable material that functions as a selective filter that allows certain chemicals to pass and restricts the passage of other chemicals. Examples of suitable porous and breathable materials for layer 43 are described above.
[0029]
Layer 43 can be sputtered, jetted, laminated, discharged, or applied to indicator layer 41 to a thickness of about 0.1 to 30 microns after support layer 41 is bonded to insulating layer 32. Alternatively, the layer 43 can be provided on the support layer 41 before the filter 45 is attached to the insulating layer 32. In this alternative method, the filter 45 may be coupled to the insulating layer 32 so that the insulating layer 32 and the substrate 11 are closer to the layer 43 than the support layer 41. This configuration is not shown in FIG. However, the filter 45 is preferably coupled to the insulating layer 32 so that when the insulating layer 32 and the substrate 11 are disposed closer to the support layer 41 than the layer 43 as shown in FIG. The holes 42 do not clog during operation of the sensor 40.
[0030]
Referring to FIG. 3, a partial cross-sectional view of yet another embodiment of the sensor of FIG. The sensor 60 of FIG. 3 is also similar to the sensor 10 of FIG. 1, and the same reference numerals are used in FIGS. 1 and 3 to indicate the same elements. In FIG. 3, the adhesive 21 bonds the insulating layer 32 and the filter 61 and forms a cavity 62 therebetween. Cavity 62 and filter 61 are similar in purpose to cavity 31 and filter 22, respectively, in FIG.
[0031]
As described above, the filter 61 is made of a porous or air-permeable material having an appropriate thickness sufficient to obtain substantial rigidity in order to prevent damage to the sensing element 14. Unlike the filter 22 of FIG. 1, the filter 61 of FIG. 3 does not have a filtering hole. Filter 61 is similar in composition to layer 43 of FIG. 2, and can have a thickness of about 50 to 500 microns.
[0032]
The sensors 10, 40, 60 of FIGS. 1, 2 and 3 each have several advantages over prior art sensors mounted in a conventional metal T05 or T39 package. For example, the cavities 31, 44, 62 of FIGS. 1, 2, and 3 each have a smaller cavity volume than the cavities or encapsulated areas of conventional metal T05 or T39 packages. Due to the small cavity volume, the sensors 10, 40, 60 are less bulky in size than conventional metal T05 or T39 packages, thus saving space in any application. Sensors 10, 40, 60 are at least 100 times smaller than conventional metal T05 or T39 packages.
[0033]
Further, since the cavity volume is small, the cavities 31, 44, and 62 can be more rapidly filled with a chemical substance having a critical concentration to be detected by the detection element 14. Because the cavity volume is small, the critical chemical concentration can also be removed faster. For this reason, the response time and refresh time of the sensors 10, 40, 60 are improved as compared with the prior art. As described above, the cavity capacity of the cavities 31, 44 and 62 can be controlled by the thickness or height of the adhesive 21. The minimum volume required for the cavities 31, 44, 62 depends on the composition and operating temperature of the sensing element 14, the chemicals to be sensed, and the diffusion rate of ambient gas or liquid into and out of the cavities 31, 44, 62.
[0034]
Further, the manufacturing process of the sensors 10, 40, 60 is less time consuming, less expensive and less labor-intensive than the prior art. If the substrate 11 and the filter 22, 45, or 61 are different semiconductor wafer portions, the sensor 10 can be created using an automated semiconductor wafer processing apparatus that reduces human intervention and improves manufacturing yield. . Thus, the creation of the sensor 10 is suitable for a mass production environment.
[0035]
Thus, the sensors 10, 40, 60 can be mounted or assembled using wafer-level batch processing, with hundreds or thousands of sensors being simultaneously mounted on a single semiconductor substrate before individual sensors. Disconnect. Through the wafer level batch mounting process, the throughput is improved, and the cost efficiency becomes higher compared to the conventional laborious process of mounting one sensor at a time separately.
[0036]
Furthermore, the wafer level mounting prevents the sensing element 14 from being damaged during die separation. This is because the sensing element 14 is enclosed in the cavity 31, 44 or 62 before the separation process. Furthermore, the adhesive 21 and the filters 22, 45, 61 make the sensors 10, 40, 60 firm and firm, respectively, and reduce the possibility of breakage. Therefore, the manufacturing yield of the sensors 10, 40, 60 is further improved as compared with the prior art.
[0037]
Thus, it is clear that the present invention provides an improved sensor that overcomes the disadvantages of the prior art. Inefficient section assembly in conventional metal T05 or T39 packages is eliminated, and cost-effective and cycle time reduced methods increase mechanical strength and improve manufacturing yield of sensor fabrication. The size of the mounted sensor is about 1/100 of that of the conventional mounted sensor. In addition, sensor performance is enhanced by improving chemical sensitivity, chemical selectivity, refresh time and response time.
[0038]
Although the invention has been particularly shown and described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. I understand. For example, humidity and temperature sensors can be provided in the cavities 31, 44, 62 to improve the monitoring functions of the sensors 10, 40, 60, respectively. Further, the processes described herein can be applied to mounting other types of sensors such as chemical field effect transistors (CHEMFETs), surface acoustic wave (SAW) devices, capacitive sensors, and the like. Accordingly, the disclosure of the present invention is not intended to be limiting. The disclosure of the present invention is intended to illustrate the scope of the invention, the scope of which is set forth in the following claims.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of a sensor according to the present invention.
2 is a partial cross-sectional view of an alternative embodiment of the sensor of FIG. 1 in accordance with the present invention.
3 is a partial cross-sectional view of another alternative embodiment of the sensor of FIG. 1 in accordance with the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Sensor 11 Substrate 12 Recess 13 Heating element 14 Sensing element 15, 16 Bonding line 17, 18 Feature 19, 20 Substrate surface 21 Adhesive 22 Filter 23, 24 Filter surface 25, 30 Contact opening 26, 27, 28, 29 Filtering Hole 31 Cavity 34, 35 Adjacent sensor 36, 37 Drawing

Claims (1)

For semiconductor parts:
A semiconductor substrate (11) having a first surface (20), a second surface (19) facing the first surface, and a recess (12) in the first surface;
An insulating layer (32) overlying the second surface (19) of the semiconductor substrate (11);
A chemically sensitive thin film (14) overlying the insulating layer (32) and the recess (12), wherein the chemically sensitive thin film (14) is not disposed within the recess;
A filter (22, 45 or 61) on and spaced apart from the chemically sensitive thin film (14), wherein the filter is insulated from all conductive layers of the semiconductor component. thing;
An adhesive (21) for bonding the filter (22, 45 or 61) to the insulating layer (32); and heating the chemically sensitive thin film under the chemically sensitive thin film (14) Heating element (13) for;
A semiconductor component comprising:

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