JPH0828492B2 - 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 semiconductor 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 charge transfer device, which is a kind of multiplexer formed on a Si substrate, are connected by an indium metal pillar to be integrated. A method of manufacturing a device, comprising forming a metal film for connecting between the island-shaped well regions.
After forming on the surface of CdTe substrate and Hg _1-X Cd _X Te substrate, resin was filled between the metal pillars, and only the CdTe substrate was selectively removed by etching while leaving the island-shaped well region. By manufacturing a semiconductor device, the occurrence of crosstalk is eliminated, and when this semiconductor device is operated at a temperature cycle between room temperature and the low temperature state when operating at 77 ° K, the heat generated between the CdTe substrate and the Si substrate is reduced. A semiconductor device in which plastic deformation does not occur in the In metal column due to the difference in expansion coefficient and which is integrated at high density is obtained.

[Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a Si substrate provided with a CdTe substrate on which an infrared detection element having photodiodes formed in an array and a signal processing circuit for a detection signal of the detection element is provided. The present invention relates to a method of manufacturing a semiconductor device connected by a pillar.

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. A semiconductor device in which the infrared detecting element and the charge transfer element are connected to each other by an In metal column is well known.

In such a semiconductor device, 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 operation at the low temperature of 77 ° K and the non-operation at the room temperature, both 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 detection element array, a photoresist film 2 having a predetermined pattern is formed on a CdTe substrate 1 as shown in FIG. 5, 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. 6, 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. 7, the substrate surface is polished to form island-shaped well regions 5 on the substrate 1.

Next, as shown in FIG. 8, 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 in the well region 5 by an ion implantation method 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.

Then, as shown in FIG. 9, 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.

The charge-coupled device on the Si substrate has a complicated drawing, so only the input section 10 and the bus line 11 are shown.

[Problems to be solved by the invention]

However, in the semiconductor device 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 detection signal.

The thermal expansion coefficient (coefficient of linear expansion) of the CdTe substrate on which the infrared detecting element consisting of the photodiode 8 is formed is + 0.9 × 10 _-6 / K at 77 ° K of 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 5 at 297 ° K when not operating.
^{At -6} / K, 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 this semiconductor device is operated in a temperature cycle between a low temperature of 77 ° K during operation and 297 ° K at room temperature,
Since the thermal expansion coefficients of the two substrates are different, there is a problem that plastic deformation occurs in the In metal column connecting the substrates.

Therefore, by forming a groove between the well regions 5 in which the photodiodes 8 are formed by using an ion milling method to separate the elements from each other, the phenomenon of crosstalk is prevented and the groove is formed. By doing so, the volume of the CdTe substrate itself was reduced, and the effect of the difference in thermal expansion coefficient between the two substrates on the In metal column was attempted to be reduced. Each infrared detection element requires two metal pillars of In for connecting between the input part of the charge transfer device and the ground part of the photodiode and the ground connection formed on the Si substrate. Results in the problem that they are not formed in high density.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and to provide a method for manufacturing a semiconductor device in which crosstalk does not occur and an obstacle due to a difference in thermal expansion coefficient between both substrates connected by an In metal pillar is prevented. .

[Means for solving problems]

A method for manufacturing a semiconductor device of the present invention to achieve the above object is to provide a predetermined pattern of mercury.
After providing a well region formed of a cadmium tellurium crystal layer and having a P-N junction and connecting the well regions with a conductive film, an output portion of the infrared detection element formed in the well region and the other semiconductor substrate The input part of the multiplexer formed in 1 is connected by a metal column, and then a resin is filled between the cadmium tellurium substrate and the semiconductor substrate, and then only the cadmium tellurium crystal forming the substrate 1 is selectively removed.

[Action]

After connecting the well regions in which the photodiodes are formed with a conductive metal film, the two substrates are connected with an In metal pillar, and then a resin is filled between the In metal pillars. Further, only the CdTe crystal is selectively etched, the Hg _1-X Cd _X Te crystal is not etched etching solution having an etching selection ratio, that is, the etching solution filed by the applicant in Japanese Patent Application No. 57-191058. The CdTe substrate having the well region of Hg _1-X Cd _X Te in which the P-N junction is formed is etched at. Then
Since only the CdTe crystal is selectively etched, only the well region is separated from the substrate, and a semiconductor device with no crosstalk can be obtained.
Since the volume of the crystal of is reduced, there is no risk of plastic deformation of the In metal column 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-mentioned eighth process.
The same is true up to the figure. That is, a P-type Hg _1-X Cd _X Te crystal is formed in the well region 5 on the CdTe substrate 1 after the steps up to FIG.
Then, the CdTe substrate 1 in which N-type impurity atoms are introduced thereinto to form the N-type layer 7 is prepared.

Then, as shown in FIG. 1, a conductive coating film 21 made of gold for connecting between the well regions 5 on the CdTe substrate 1 is formed by a vapor deposition method and then formed into a predetermined pattern by a photolithography method. .

Next, as shown in FIG. 2, the N-type layer 7 serving as the output portion of the photodiode 8 and the input diode 10 formed on the Si substrate 9 are connected using the In metal pillar 12.

Further, as shown in FIG. 3, epoxy resin is used between the In metal columns 12.
Fill 22. By doing so, when only the CdTe substrate is selectively etched in a state where only the well region remains in the subsequent step, the well region is thin, and therefore, it serves to reinforce this.

Then, as shown in FIG. 4, it was connected with In metal columns 12.
The substrate 1 of CdTe is hydrofluoric acid (HF), nitric acid (HNO ₃ ), acetic acid (CH ₃ COOH), and water (H ₂ O) in a weight ratio (2-5):
(3 to 5): Etching is performed by immersing in an etching solution mixed so as to have a mixing ratio of 6: 6, that is, the etching solution filed by the applicant of the present application in Japanese Patent Application No. 57-191058. Then, this etching solution forms Hg _1-X Cd _X which forms the well region 5.
Only the CdTe crystal is selectively etched without etching the Te crystal, and the CdTe substrate other than the well region 5 is selectively etched with the Hg _1-X Cd _X Te well region 5 remaining. .

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. When this semiconductor device was used in the temperature cycle of 77 ° K operation and 297 ° K non-operation, the CdTe substrate crystal was removed, and the difference in the coefficient of thermal expansion between the Si substrate and the CdTe substrate caused In.
There is an effect that an accident that causes plastic deformation of the metal column is eliminated and a highly reliable semiconductor device can be obtained.

Further, since it is sufficient to form only one output In metal column 12 for each infrared detection element, the density of the semiconductor layer formed can be increased.

〔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 semiconductor device integrated with high density in which plastic deformation of metal bumps does not occur and crosstalk does not occur can be obtained.

[Brief description of drawings]

1 to 4 are sectional views showing the steps of the method for manufacturing a semiconductor device of the present invention, and FIGS. 5 to 9 are sectional views showing the steps of the conventional method for manufacturing a semiconductor device. In the figure, 1 is a CdTe substrate, 5 is a well region, 7 is an N-type layer, 8 is a photodiode, 9 is a Si substrate, 10 is an input diode, and 12 is In.
A metal column, 21 is a conductive coating, and 22 is a resin.

 ─────────────────────────────────────────────────── ─── 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) comprising a mercury-cadmium-tellurium crystal layer of a predetermined pattern, comprising a P-N
A well region (5) having a junction is formed, and an output portion of the infrared detecting element formed in the well region (5) and an input portion of the multiplexer formed on the other semiconductor substrate (9) are connected to a metal column (12). And then the resin (22) is filled between the cadmium tellurium substrate (1) and the semiconductor substrate (9), and then only the cadmium tellurium crystal forming the substrate (1) is selectively removed. And a method for manufacturing a semiconductor device.