JPH05283757A - Photoelectric conversion element - Google Patents

Abstract

PURPOSE:To provide a photoelectric conversion element which can be stably assembled by use of a vacuum suction type die bonding device and sucked by a vacuum suction collet as pasted on an adhesive tape as it is kept as a wafer. CONSTITUTION:A cover 10 is joined to a photoelectric conversion element covering a conversion section 4 so as to enable the photoelectric conversion element to be sucked by a vacuum suction collet without causing damage to the conversion section. Furthermore, a cover 10 is joined to the rear side of a substrate 1 so as to enable the photoelectric conversion element to be pushed up without damaging a support 3. In this case, a space produced between the cover 10 and the conversion section 4 is lessened enough in pressure, whereby a photoelectric conversion element can be lessened in thermal energy loss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a thin film support on a substrate having a hollow portion in the center thereof, and a conversion unit for converting thermal energy of a thin film into electric energy on the surface of the support. The present invention relates to a photoelectric conversion element in which an absorber is provided on the conversion unit via an insulating film.

[0002]

2. Description of the Related Art A photoelectric conversion element for converting infrared energy into electric energy will be described below as an example. FIG. 4 shows an example of a conventional photoelectric conversion element of this type. In the figure, 1
Is a substrate, 2 is a cavity provided in the central portion of the substrate 1, 3 is a thin film-like support provided on the substrate 1, and 4 is a thermocouple or a thin film having a pyroelectric effect provided on the surface of the support 3. Is a conversion part for converting heat energy into electric energy, 5 is an insulating film provided on the conversion part 4, 6 is an absorber for converting incident light into heat energy provided on the insulating film 5, and 7 is an absorber 6 Is a protective film that covers.

In this type of photoelectric conversion element, in order to improve conversion efficiency, the conversion portion 4 is provided on the surface of the thin film-shaped support 3 on the cavity 2 provided in the central portion of the substrate 1, and the conversion portion 4 is provided. Adopts a structure that reduces the heat capacity of. Infrared rays pass through the protective film 7 and enter the absorber 6, are converted into heat energy,
This thermal energy is converted into electric energy by the conversion unit 4, and a voltage is output from the output electrode.
For manufacturing, a method of arranging and forming on a wafer by a normal semiconductor microfabrication technique and dicing into individual elements is adopted.

In the photoelectric conversion device having the above-mentioned structure, when a vacuum suction type die bonding device is used for die bonding in order to improve the assembly work efficiency, the mechanical strength of the conversion portion is very weak. There is a problem that the conversion part of the thin film structure is damaged when the collet for vacuum adsorption comes into contact with it. In order to solve the above problem, as shown in FIG.
There is provided a structure in which the substrate 1 has a rectangular shape, the conversion portion 4 having weak mechanical strength is provided at a position deviated from the center of the substrate 1, and a portion having mechanical strength required for vacuum suction is widened.
However, in the above method, the size of the photoelectric conversion element is increased, so that the number of wafers that can be taken from one wafer is reduced, and the cost is increased. In addition, since the adsorption part at the time of assembly is offset from the center of the element, the pressure is unevenly applied to the element during die-bonding to the package. May be inclined and adhered, and in this case, there is a problem that the thin film of the conversion portion is distorted, which causes output fluctuation. Figure 5
4, the same reference numerals as those in FIG. 4 indicate the same or corresponding portions, and 8 is an output electrode.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure in which a vacuum suction type die bonding apparatus can be used for die bonding without changing the planar structure and dimensions of the element. In addition, in order to improve work efficiency, it is attached on an adhesive tape in a wafer state, and individual elements are separated from the tape by pushing up from the bottom of the tape with pins, and with a structure that can be adsorbed with a vacuum adsorption collet,
The purpose is to reduce heat energy loss and increase conversion efficiency.

[0006]

According to the present invention, in order to protect a conversion unit from mechanical shock so that a vacuum suction type die bonding apparatus can be used for die bonding, a light transmission layer covering the conversion unit on a surface of a support is transmitted. A cover with a recess is joined to the central part made of a conductive material so that it does not come into contact with the conversion part.Furthermore, at the time of die bonding, it is affixed to the adhesive tape in the wafer state and pushed up with a pin from the bottom of the tape to separate individual Separated from the tape and sucked with a vacuum suction collet,
In order to protect the thin film support from the pins pushed up from the bottom and to reduce the loss of heat energy from the conversion part, the conversion part is in contact with the center part made of a light-transmissive material that covers the conversion part on the surface of the support. In order to prevent this, a cover provided with a concave portion is bonded to an airtight structure by sufficiently lowering the pressure in the concave portion, and a cover for covering the hollow portion in the central portion of the substrate on the back surface of the substrate is made sufficiently low in the hollow portion. Joined to the airtight structure.

[0007]

1 and 2 show an embodiment of the present invention. In the drawings, the same reference numerals as those in FIGS. 4 and 5 denote the same or corresponding portions, 10 is a cover formed of a light-transmitting material such as silicon, and 11 is provided in the central portion of the cover 10 so as not to come into contact with the conversion portion 4. The concave portion 12 is a convex portion in the peripheral portion of the cover 10, 13 is a bonding agent such as low melting point glass, and 14 is an open portion provided to expose the output electrode 8 in a part of the peripheral portion of the cover 10.

Cover 1 for the surface of the support 3 of the photoelectric conversion element
In the bonding of 0, the wafer having the cover 10 formed in the same arrangement as the photoelectric conversion elements is overlaid and bonded onto the wafer formed by arranging the photoelectric conversion elements having the conventional structure. The cover 10 has
An infrared transparent silicon wafer is used. A bonding agent 13 such as low melting point glass or low melting point metal is formed on the entire surface of the silicon wafer by sputtering or the like, and the bonding agent 13 in the recess 11 region of the cover 10 is removed by etching using the photoresist as a mask. In the case of low melting glass, it can be easily etched with hydrofluoric acid. Next, the bonding agent 1
3, or silicon is selectively etched using the bonding agent 13 and the resist as a mask, and the etching depth is 1
The cover 10 is formed of a concave portion 11 of 0 μm to 100 μm and a convex portion 12 having the bonding agent 13 attached to the surface thereof. This wafer is placed on a wafer formed by arranging photoelectric conversion elements having a conventional structure with the concave portion 11 of the cover 10 and the converting portion 4 aligned with each other, and a weight for applying pressure is placed on the wafer, and the wafer is placed on a hot plate. Heat to 400-500 ° C and bond 1
Melt 3 and join. After that, it is cooled and separated into individual elements by dicing.

FIG. 3 shows an embodiment of the invention of claim 2.
In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and 15 is a cover for covering the cavity 2 of the substrate 1 bonded to the back surface of the substrate 1. A silicon wafer is also used for the cover 15, the bonding agent 13 is formed on the entire surface of the silicon wafer, and a wafer formed by arranging photoelectric conversion elements having a conventional structure on this wafer is aligned with the bonding position, and then the wafer is formed. 1, the wafer formed by arranging the covers 10 shown in the explanation of FIG. 1 is placed with the bonding positions aligned, placed on a hot plate, a weight is placed on the wafer, and the whole hot plate is placed in a vacuum apparatus. When the material is evacuated and heated with a hot plate while the pressure is sufficiently reduced, the bonding agent 13
Melts, and the inside of the recess 11 and the inside of the cavity 2 can be bonded to an airtight structure while maintaining a sufficiently low pressure. After that, the wafer is cooled and the bonded wafer is taken out from the vacuum apparatus and separated into individual elements by dicing.

At the time of bonding, instead of using a weight for pressurization, the wafer is fixed using an appropriate jig, and when the bonding agent 13 is heated and melted, a rapid exhaust valve or the like is used in the vacuum apparatus. May be returned to the atmospheric pressure in a short time. According to this method, the pressure difference between the pressure inside the cavity 2 and the recess 11 and the atmospheric pressure on the outside causes the pressure to be applied to the entire wafers of the upper and lower covers 10 and 15. It is evenly applied and can be bonded to a better airtight structure.

In the structure shown in FIGS. 1 and 2, since the cover 10 can be sucked by the suction collet without damaging the thin film conversion portion 4, die bonding can be performed by using a vacuum suction type die bonding apparatus. And work efficiency increases. In the structure shown in FIG. 3, the thin film-like support body 3 is protected by the cover 15 and is not destroyed even when it is attached to an adhesive tape in a wafer state and pushed up by a pin from below, and separated elements are separated. Since it is not necessary to align them on the tray, work efficiency is further improved. Further, since the pressures inside the cavity 2 and the recess 11 are sufficiently low, the energy lost from conduction and convection through the gas from the conversion unit 4 as in the conventional case is almost eliminated, the conversion efficiency is increased, and the output is increased.

[0012]

As described above, according to the present invention,
A vacuum suction type die bonding device can now be used for die bonding, and furthermore, it is attached to an adhesive tape in a wafer state and pushed up with a pin from below to separate individual elements,
The vacuum suction collet can be used for suction, which improves the assembly work efficiency and enables stable mass production. Moreover, the loss of heat energy is reduced, the conversion efficiency is increased, and the output is increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the invention of claim 1.

FIG. 2 is a plan view showing an embodiment of the invention of claim 1;

FIG. 3 is a sectional view showing an embodiment of the invention of claim 2;

FIG. 4 is a sectional view showing an example of a conventional photoelectric conversion element of this type.

FIG. 5 is a plan view showing an example of a photoelectric conversion element conventionally provided for using a vacuum suction type die bonding apparatus for die bonding.

[Explanation of symbols]

 1 Substrate 2 Cavity 3 Support 4 Conversion 5 Insulator 6 Absorber 7 Protective film 8 Output electrode 10 Cover 11 Recess 12 Convex 13 Bonding agent 14 Opening 15 Cover

Claims (2)

[Claims] 1. A thin film-shaped support is provided on a substrate having a hollow portion in the center, and a conversion unit for converting thermal energy of the thin film into electric energy is provided on the surface of the support, and the conversion unit is provided on the conversion unit. In a photoelectric conversion element having an absorber provided via an insulating film, a cover provided with a recessed portion on the surface of the support body so as not to come into contact with the conversion unit is formed in the central portion made of a light-transmissive material that covers the conversion unit. A photoelectric conversion element characterized by being joined. 2. A thin film-shaped support is provided on a substrate having a hollow portion in the center, and a conversion unit for converting thermal energy of the thin film into electric energy is provided on the surface of the support, and on the conversion unit. In a photoelectric conversion element having an absorber provided via an insulating film, a cover provided with a recessed portion on the surface of the support body so as not to come into contact with the conversion unit is formed in the central portion made of a light-transmissive material that covers the conversion unit. The pressure in the recess is made sufficiently low to bond to the airtight structure, and the cover for covering the cavity in the central portion of the substrate is bonded to the airtight structure on the back surface of the substrate by sufficiently lowering the pressure in the cavity. Characteristic photoelectric conversion element.