JPH0983007A - Semiconductor radiation detecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor radiation detecting element in which a passivation film providing excellent protection is provided on the surface of an element and strong solder bumps are provided thereon while facilitating the fabrication. SOLUTION: A semiconductor crystal 7 is provided with a common electrode 6 on one side thereof and a plurality of pixel electrodes 5 on the other side. The one side is coated with an organic insulating film 1 and an opening is made by etching at the joint A of pixel electrode 5 and a solder bump 3. Furthermore, a metal film 2 adhering well to all of the solder, organic insulating film 1 and the metal of pixel electrode 5 is formed on the joint A and the surroundings B thereof before forming a solder bump 3 on the metal film 2. Consequently, the semiconductor crystal is protected well thus obtaining an element where the solder bump has high strength. A large number of elements are arranged one-dimensionally or two-dimensionally thus realizing an excellent radiation image measuring unit in which deterioration and missing of pixel are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor radiation detecting element applicable to a radiation image measuring device or the like for obtaining a radiation transmission image of an object by utilizing radiation in the medical field, non-destructive inspection field, etc. The semiconductor radiation detecting element of the present invention can be used as a line sensor or a surface sensor by arranging it in a one-dimensional or two-dimensional manner.

[0002]

_2. Description of the Related Art A compound semiconductor such as CdTe, GaAs, or HgI ₂ is provided with a common electrode for bias supply on one of the opposite surfaces, and a plurality of pixel electrodes for extracting signals on the other surface. A semiconductor radiation detecting element provided with a solder bump for obtaining a connection with a printed circuit board or the like is disclosed in, for example, Japanese Patent Laid-Open No. 3-188688.
FIG. 4 shows a conventional semiconductor radiation detecting element with solder bumps (cross-sectional view). The common electrode 6 and the individual electrode 5 are formed on two opposing surfaces of the compound semiconductor crystal 7, and the individual electrode 5
Is provided with solder bumps 3. Further, a passivation film 41 is provided between the solder bump 3 and the compound semiconductor crystal 7.
Are formed.

[0003]

In the structure of the semiconductor radiation detecting element shown in FIG. 4, the passivation film 41 formed for the purpose of maintaining the shape of the solder bump 3 and protecting the semiconductor surface is made of SiOx or SiNx. A film formed by vacuum evaporation, ECR plasma CVD, or the like is used. These films are used for the compound semiconductor substrate 7 and the metal pixel electrode 5 from the both sides of the material and the manufacturing method.
It turns out that the adhesion is not very good.

Further, in the manufacturing method thereof, the opening portion of the passivation film which becomes the joint portion A between the solder bump 3 and the pixel electrode 5 is formed by the lift-off method. The lift-off method becomes difficult as the film thickness increases, so
There is a trade-off relationship between the semiconductor surface protection effect and the manufacturing efficiency.

Further, the portion where the solder bump 3 is joined to the detection element is only the joint portion A where it is joined to the pixel electrode 5, and the material of the pixel electrode 5 is the adhesive strength to the solder for the purpose of increasing the joining strength. There was a limitation that you had to choose the higher one.

An object of the present invention is to solve the above-mentioned problems and to provide a semiconductor radiation detecting element in which the semiconductor surface is well protected and the solder bump is joined to the detecting element with high joining strength.

[0007]

In order to solve the above-mentioned problems, the present invention provides a semiconductor radiation detecting element in which at least one of the electrodes formed on two opposite surfaces of a semiconductor crystal has a plurality of electrodes. An organic insulating film is formed on the surface on which the plurality of electrodes are formed, excluding a part of each of the plurality of electrodes, and a solder bump is formed on a part of each electrode on which the organic insulating film is not formed. Was formed.

As yet another means for solving the problem, in a semiconductor radiation detecting element in which at least one of the electrodes formed on the two opposite surfaces of the semiconductor crystal has a plurality of electrodes, the surface on which the plurality of electrodes are formed. An organic insulating film is formed on the organic insulating film except a part of each of the plurality of electrodes, and one layer or a layer is formed on the part of each electrode on which the organic insulating film is not formed and on the surrounding organic insulating film. A multilayer metal film was formed, and solder bumps were formed on the metal film.

In the present invention, as the passivation film, an organic insulating film made of polyimide, polyamide or the like, which can be baked at a low temperature, has good adhesion to various substances, and can be patterned by etching, is used. The formation is from 200 ° C
Since it can be fired at a relatively low temperature of 300 ° C., it is suitable for a semiconductor radiation detecting element using a compound semiconductor such as CdTe or GaAs which is transformed at a high temperature. This organic insulating film has good adhesion to various substances other than solder, has excellent chemical resistance, and can form a thick film because it can be patterned by etching. It has excellent effects in holding and protecting the element surface.

Further, the solder bump is bonded not only to the bonding portion with the pixel electrode but also to the peripheral portion of the bonding portion on the organic insulating film through the metal film having high adhesion, so that the solder bump and the detection element are connected. The joint area with and increases, and the joint strength becomes significantly stronger. This metal film may be a multilayer film in which the uppermost layer is a metal having good adhesion to solder and the lowermost layer is a metal having good adhesion to the organic insulating film and the pixel electrode.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram (cross-sectional view) showing an embodiment of the invention described in claim 1. The common electrode 6 is formed on one of the two facing surfaces of the semiconductor crystal 7, and the plurality of pixel electrodes 5 are formed on the other surface.
The organic insulating film 1 is formed so as to cover the entire surface on which the pixel electrode 5 is formed, and the opening of the organic insulating film is formed in the central portion A of each pixel electrode 5 by etching. This portion becomes a joint with the solder bump. Further, a solder bump 3 is formed on the joint portion A by electroplating with a plating current supply metal film 4 of Au, Al, or the like interposed therebetween. After forming the solder bumps 3, the plating current supply metal film 4 is removed by a method such as lift-off or etching except for the portion of the joint portion A. In the above steps, the pattern formation is performed by a photolithography technique including photoresist coating, prebaking, pattern exposure, and development.

The metal species used for the electrodes 5 and 6 is A
u, Pt, Ni, Al or the like is used, and is not particularly limited. The metal film 4 for supplying the plating current is also made of Au, A
It is not limited to 1 and may be a multilayer film of Au + Ni or the like. Polyimide or polyamide is used for the organic insulating film 1, but any other material may be used as long as the baking temperature is 300 ° C. or lower and the chemical resistance is high.

FIG. 2 is a diagram (cross-sectional view) showing an embodiment of the invention described in claim 2. In FIG. The common electrode 6 is formed on one of the two facing surfaces of the semiconductor crystal 7, and the plurality of pixel electrodes 5 are formed on the other surface. The organic insulating film 1 is formed so as to cover the entire surface on which the pixel electrode 5 is formed, and the opening of the organic insulating film is formed in the central portion A of each pixel electrode 5 by etching. This portion becomes a joint with the solder bump. Further, an adhesive metal film 2 of Al, Ni or the like is formed on the joint portion A and the peripheral portion B thereof. Moreover, Au, A
The solder bumps 3 are formed by electroplating through the metal film 4 for supplying the plating current such as l. After forming the solder bumps 3, the plating current supply metal film 4 is removed by a method such as lift-off or etching except for the adhesive metal film 2. In the above steps, pattern formation is
It is performed by a photolithography method including photoresist coating, pre-baking, pattern exposure, and development.

The metal species used for the electrodes 5 and 6 is A
u, Pt, Ni, Al or the like is used, and is not particularly limited. The size (A + B) of the adhesive metal film 2 is
Any number of electrodes may be used as long as they are not in contact with each other. The material is not limited to Al and Ni, and may be any metal as long as it has good adhesion to all the metals of the solder, the organic insulating film 1 and the pixel electrode 5. The metal 4 for supplying the plating current is also Au,
The multilayer film is not limited to Al and may be a multilayer film of Au + Ni or the like. Polyimide or polyamide is used for the organic insulating film 1, but any other material may be used as long as the baking temperature is 300 ° C. or lower and the chemical resistance is high.

FIG. 3 is a view (cross-sectional view) showing another embodiment of the invention described in claim 2. In FIG. The common electrode 6 is formed on one of the two facing surfaces of the semiconductor crystal 7, and the plurality of pixel electrodes 5 are formed on the other surface. The organic insulating film 1 is formed so as to cover the entire surface on which the pixel electrode 5 is formed, and an opening is formed in the central portion A of each pixel electrode 5 by etching. This portion becomes a joint with the solder bump. Further, on the joint portion A and its peripheral portion B, a multi-layered adhesive metal film 2 of Au + Cu + Ni or the like is formed.
1 + 22 + 23 is formed. Further, the solder bumps 3 are formed on the uppermost layer 21 of the adhesive metal film by electroplating with the plating current supply metal film 4 of Au, Al or the like interposed therebetween. After forming the solder bumps 3, the plating current supply metal film 4 is removed by a method such as lift-off or etching except for the adhesive metal films 21 + 22 + 23. In the above steps, the pattern formation is performed by a photolithography technique including photoresist coating, prebaking, pattern exposure, and development.

The metal species used for the electrodes 5 and 6 is A
u, Pt, Ni, Al or the like is used, and is not particularly limited. The size (A + B) of the adhesive metal films 21 + 22 + 23 may be any size as long as they are not in contact with each other. The material is not limited to Au + Cu + Ni, and may be a multilayer film such as Au + Pt + Ti or Au + Cu + Cr as long as the uppermost layer 21 has good adhesion to solder and the lowermost layer 23 has good adhesion to the metal of the organic insulating film 1 and the pixel electrode 5. I do not care. Since the intermediate layer 22 is a metal sandwiched when the adhesion between the metal of the uppermost layer 21 and the metal of the lowermost layer 23 is not good, it may be a multilayer film.
In some cases, it may not be necessary. Metal 4 for supplying plating current
Is not limited to Au and Al, but may be a multilayer film of Au + Ni or the like. Polyimide or polyamide is used for the organic insulating film 1, but if the organic insulating film 1 is other than this, the baking temperature is 30.
Any material that is resistant to chemicals at 0 ° C or lower may be used.

As the semiconductor crystal 7 used in the above three embodiments, CdTe, GaAs, HgI ₂ , CdZ are used.
The present invention can also be applied to compound semiconductor crystals and organic semiconductor crystals other than these, in which compound semiconductor crystals such as nTe are used, and simple substance semiconductor crystals. 1 to 3 are cross-sectional views of the semiconductor radiation detecting element according to the present invention seen from the side, it can be seen that a plurality of pixel electrodes 5, solder bumps 3 and the like are arranged one-dimensionally. It goes without saying that the present invention includes the case where the pixel electrodes 5 and the like are arranged two-dimensionally.

[0018]

The semiconductor radiation detecting element of the present invention has an organic insulating film excellent in protection of the element surface between the semiconductor crystal and the solder bump and has a solder bump having high strength. The surface is well protected, and deterioration of characteristics and loss of solder bumps are unlikely to occur. By arranging a large number of the semiconductor radiation detecting elements of the present invention in a one-dimensional form or a two-dimensional form, it is possible to realize an excellent radiation image measuring apparatus without deterioration or pixel loss.

[Brief description of drawings]

FIG. 1 is a diagram (cross-sectional view) showing an embodiment of the invention described in claim 1. FIG.

FIG. 2 is a diagram (cross-sectional view) showing an embodiment of the invention described in claim 2;

FIG. 3 is a diagram (cross-sectional view) showing another embodiment of the invention described in claim 2;

FIG. 4 is a diagram (cross-sectional view) showing a structure of a conventional radiation detecting element with solder bumps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Organic insulating film 2 ... Adhesive metal film 3 ... Solder bump 4 ... Plating current supply metal film 5 ... Pixel electrode 6 ... Common electrode 7 ... Semiconductor crystal 21 ... Adhesive metal film upper layer 22 ... Adhesive metal film intermediate layer 23 ... Adhesive metal film lower layer 41 ... Passivation film

Claims (2)

[Claims] 1. A semiconductor radiation detecting element having a plurality of electrodes on at least one surface among electrodes formed on two opposing surfaces of a semiconductor crystal, wherein the plurality of electrodes are formed on the surface on which the plurality of electrodes are formed. A semiconductor radiation detecting element, characterized in that an organic insulating film is formed excluding a part of each of the electrodes, and a solder bump is formed on a part of each electrode on which the organic insulating film is not formed. 2. A semiconductor radiation detecting element, wherein at least one of the electrodes formed on two opposing surfaces of a semiconductor crystal has a plurality of electrodes, and the plurality of electrodes are formed on the surface on which the plurality of electrodes are formed. An organic insulating film is formed excluding a part of each of the individual electrodes, and a single-layer or multi-layer metal film is formed on a part of each electrode where the organic insulating film is not formed and on the surrounding organic insulating film. A semiconductor radiation detecting element, which is formed and solder bumps are formed on the metal film.