JPH0828491B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] An island-shaped well region made of a predetermined pattern of mercury, cadmium, and tellurium (Hg _1-X Cd _X Te) is formed on a CdTe substrate,
A hybrid type in which a P-N junction is formed in the well region to form a photodiode, and the photodiode and an input portion of a multiplexer such as a charge transfer device formed on a Si substrate are connected by an indium metal pillar to be integrated. Crosstalk occurs in the photoelectric conversion element by selectively removing the CdTe crystal by etching while leaving the island-shaped well region of the CdTe substrate of the infrared detector to manufacture a semiconductor device. When this semiconductor device is operated in a temperature cycle between a low temperature state at 77 ° K and a room temperature, the In metal column is plastically deformed due to the difference in thermal expansion coefficient between the CdTe substrate and the Si substrate. So that it does not occur.

[Industrial applications]

The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a hybrid type red connecting a metal substrate to an infrared detection element in which photodiodes are formed in an array on a CdTe substrate and a Si substrate provided with a signal processing circuit for a detection signal of the detection element. The present invention relates to a method for manufacturing an outer detector.

An output part of an infrared detection element in which photodiodes are arranged in an array on a compound semiconductor substrate made of mercury, cadmium and tellurium, and an input of a charge transfer element which is provided on a Si substrate and which processes a detection signal detected by the detection element. IRCC which is a kind of hybrid type infrared detector in which the infrared detection element and the charge transfer element are integrated with each other by an In metal column.
D (infrared detection charge transfer device) is well known.

In such an IRCCD, the occurrence of crosstalk is eliminated, and due to the difference in the thermal expansion coefficient between the compound semiconductor substrate and the Si substrate during the temperature cycle between the low temperature operation at 77 ° K and the non-operation at room temperature There is a demand for a device that does not cause plastic deformation in the In metal columns connecting the substrates.

[Conventional technology]

Conventionally, when forming such an infrared detecting element array, a photoresist film 2 having a predetermined pattern is formed on a CdTe substrate 1 as shown in FIG. 2, and the photoresist film 2 is used as a mask for bromine (Br ₂ ) and methyl alcohol. The groove 3 is formed using an etching solution composed of (CH ₃ OH).

Then, as shown in FIG. 3, P-type Hg _1-X Cd _X Te is formed on the substrate 1 including the groove 3 by a liquid phase epitaxial growth method or the like.
To form a crystal 4.

Next, as shown in FIG. 4, the surface of the substrate is polished to form island-shaped well regions 5 on the substrate 1.

Next, as shown in FIG. 5, a photoresist film 6 having a predetermined pattern is formed on the substrate, and boron (B) which becomes an N-type impurity in the well region 5 is formed by ion implantation using the photoresist film 6 as a mask. Atoms are ion-implanted to form an N-type layer 7, and a P-N junction is formed to form a photodiode 8.

Next, as shown in FIG. 6, after the photoresist film 6 is removed, the N-type layer 7 of the photodiode 8 is removed.
Between the output section and the input diode 10 of the charge transfer device formed on the Si substrate 9, the well region 5 in which the photodiode 8 is formed, and the charge transfer device are formed.
The bus line 11 for earth connection provided on the Si substrate 9 is connected using In metal columns 12 and 13, respectively.

[Problems to be solved by the invention]

However, in the IRCCD formed by such a method, the photons incident between the adjacent photodiodes 8 are photoelectrically converted into carriers, and the carriers flow into the adjacent photodiodes, and are detected by both photodiodes. There is a problem of causing crosstalk in the signal.

The thermal expansion coefficient (coefficient of linear expansion) of the CdTe substrate on which the infrared detection element composed of the photodiode 8 is formed is + 0.9 × 10 _-6 / K at 77 ° K, which is the operating temperature of the device. The Si substrate 8 forming the transfer device is -0.5 × 10 ^-6 / K, and the thermal expansion coefficient of the CdTe substrate is 5.0 × 10 ^-6 / K at 297 ° K when not operating.
Thus, the coefficient of thermal expansion of the Si substrate is 2.5 × 10 ^-6 / K, and the coefficient of thermal expansion is different for both substrates.

Therefore, when the IRCCD is operated at a temperature cycle between 297 ° K at room temperature and 77 ° K at room temperature, the thermal expansion coefficients of both substrates are different, so the substrates are connected.
In There is a problem that plastic deformation occurs in metal columns.

The present invention eliminates the above-mentioned problems, does not cause crosstalk, and prevents plastic deformation of the In metal columns due to the difference in the thermal expansion coefficient of both substrates connected by the In metal columns. The purpose is to provide a manufacturing method.

[Means for solving problems]

A method for manufacturing a semiconductor device of the present invention to achieve the above object is to provide a cadmium tellurium substrate with a predetermined pattern of mercury.
After forming a photoelectric conversion element by forming a well region formed of a cadmium tellurium crystal layer and having a P-N junction formed therein, the output section of the photoelectric conversion element and the input section of the multiplexer formed on the other semiconductor substrate are made of metal. After connecting by pillars, only the cadmium tellurium crystal of the substrate forming the photoelectric conversion element is selectively removed.

[Action]

After connecting the output part of the photodiode formed on the CdTe substrate and the input part of the charge transfer device with an In metal column, the CdTe substrate on which the photodiode is formed is selectively etched by the CdTe crystal and Hg _1-X Cd _{The X} Te crystal is an Hg _1-X Cd _X which forms a PN junction with an etching solution having an etching selection ratio such that it does not etch, that is, the etching solution filed by the applicant in Japanese Patent Application No. 57-191058. Etch CdTe substrate with Te well region. Then, only the CdTe crystal is selectively etched, so that only the well region is separated from the substrate, and a semiconductor device without crosstalk is obtained. Further, since the volume of the CdTe substrate is reduced by the above method, the In metal column is not plastically deformed due to the difference in the coefficient of thermal expansion between the CdTe substrate and the Si substrate.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

The process of the method for manufacturing a semiconductor device according to the present invention is the same as the above-described second step.
From FIG. 6 to FIG. 6, the same applies.

Then, as shown in FIG. 1, the CdTe substrate 1 connected to the Si substrate 9 by the In metal column 12 and the In metal column 13 was treated with hydrofluoric acid (HF), nitric acid (HNO ₃ ) and acetic acid (CH ₃ COOH). ) And water (H ₂ O) are mixed in a weight ratio of (2 to 5) :( 3 to 5): 6: 6, that is, the applicant of the present invention, Etching is performed by immersing in the etching solution applied for in No. 57-191058.

Then, this etching solution forms the well region 5.
With the Hg _1-X Cd _X Te crystal not etched, only the CdTe crystal was selectively etched, leaving the well region 5 of Hg _1-X Cd _X Te, and the CdTe substrate other than the well region 5 was removed. It is selectively etched.

By doing this, the part of the CdTe substrate disappears,
Since the well region 5 in which the photodiode 8 is formed is completely insulated and separated, the phenomenon of crosstalk does not occur. Also, when this semiconductor device is used in a temperature cycle of 77 ° K operation and 297 ° K non-operation, the CdTe substrate crystal is removed, so that the difference in the thermal expansion coefficient between the Si substrate and the CdTe substrate is caused.
In It is possible to obtain a highly reliable semiconductor device by eliminating the accident that plastic deformation of the metal pillar occurs.

〔The invention's effect〕

As described above, according to the method for manufacturing a semiconductor device of the present invention, there is an effect that a plastic deformation of the metal bump does not occur and a semiconductor device in which crosstalk does not occur can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method for manufacturing a semiconductor device according to the present invention, and FIGS. 2 to 6 are sectional views showing a conventional method for manufacturing a semiconductor device. In the figure, 5 is a well region, 7 is an N-type layer, 8 is a photodiode, and 9 is
Is Si substrate, 10 is input diode, 11 is bus line, 12,1
3 indicates a metal column.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-42175 (JP, A) JP-A-61-214462 (JP, A) JP-A-62-232958 (JP, A)

Claims (1)

[Claims] 1. A cadmium tellurium substrate (1) is formed with a well region (5) of mercury-cadmium-tellurium having a P-N junction formed thereon to form a photoelectric conversion element, and then an output portion of the photoelectric conversion element is formed. The input part of the multiplexer formed on the other semiconductor substrate (9) is connected by a metal column (12), and then only the cadmium tellurium crystal of the substrate (1) on which the photoelectric conversion element is formed is selectively removed. A method of manufacturing a semiconductor device, comprising: