JPH0797654B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] An island-shaped well region made of mercury-cadmium-tellurium (Hg _1-X Cd _X Te) having a predetermined pattern is formed on a cadmium-tellurium (CdTe) substrate, and the well region is formed. A P-N junction is formed inside to form a photodiode, and the island region is formed on the substrate.
A method of manufacturing an infrared detection element array having a structure in which insulation is performed using a CdTe crystal, wherein after the island-shaped well region is formed, CdTe is formed.
The CdTe crystal on the substrate is selectively etched using a selective etching solution of Te to lift the well region of the island-shaped Hg _1-X Cd _X Te crystal from the substrate and form a step at the boundary position between the CdTe crystal and the well region of the substrate. Then, a mask for introducing impurities of opposite conductivity type into the well region is formed on the substrate with reference to the position of the step, and the impurity atoms are introduced by using the mask. (EN) A mask aligning step can be reliably performed when introducing an impurity atom of opposite conductivity type into a well region.

[Industrial application field]

The present invention relates to a method for manufacturing an infrared detecting element, and more particularly to a method for manufacturing a semiconductor device in which photodiodes are formed in an array on a CdTe substrate.

An infrared detector array having photodiodes arranged in an array on a compound semiconductor substrate made of mercury, cadmium, and tellurium is required to have higher density and more elements. As the number of devices increases, carriers generated by photons entering between adjacent devices flow into both devices, and the carriers that flow into both devices affect the detection signals detected by both devices. A crosstalk phenomenon that causes In order to reduce this crosstalk phenomenon, it is desired to have a function corresponding to a channel stop that electrically insulates and separates elements.

Therefore, mercury, cadmium, tellurium (Hg
_1-X Cd _X Te) is formed into an island shape to form a well region, and an impurity atom having a conductivity type opposite to that of the well region is introduced into the well region to form a P-N junction to form a photodiode. To form. Then, a structure is adopted in which the photodiode is isolated by a substrate forming material having a large energy band gap, that is, a CdTe crystal.

[Conventional technology]

Conventionally, when forming such an infrared detecting element array, as shown in FIG. 7, a P-type Hg _1-X Cd _X is formed in the groove 2 formed in the CdTe substrate 1 by using a liquid phase epitaxial growth method or the like.
Crystals of Te are formed in an island shape as the well region 3.

Next, as shown in FIG. 8, a photoresist film 4 having a predetermined pattern is formed on the substrate, and the photoresist film 4 is used as a mask to ion-implant the well region 3 with N.
By implanting boron (B) atoms, which become impurities of the
A mold layer 5 is formed and a P-N junction is formed to form a photodiode 6.

[Problems to be solved by the invention]

By the way, when the photoresist film 4 is formed in a predetermined pattern, since the well region 3 is formed in the same plane as the surface of the substrate 1, it is necessary to expose the photoresist film 4 in a predetermined pattern on the substrate. Since there is no reference for aligning the photomask, it is necessary to separately form an alignment mark for aligning the photomask at a predetermined position on the substrate, which causes a problem of complicated work.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and provide a method of manufacturing a semiconductor device in which an alignment position of a reference position of an exposure mask can be formed on a substrate when aligning an exposure mask with a photoresist film. And

[Means for solving problems]

A method for manufacturing a semiconductor device of the present invention to achieve the above object is to form a well region using a predetermined pattern of Hg _1-X Cd _X Te layer on a CdTe substrate, and then use the substrate with a selective etching solution of CdTe. And selectively projecting the well region in advance to form a step at the boundary between the substrate and the well region, and for introducing an impurity atom of opposite conductivity type into the well region with reference to the position of the step. The method includes the steps of forming a mask on the substrate and introducing the impurity atoms using the mask.

[Action]

An etching solution having an etching selection ratio that selectively etches only CdTe crystals and does not etch Hg _1-X Cd _X Te crystals, that is, the etching solution filed by the applicant in Japanese Patent Application No. 57-191058. Hg _1-X C forming a P-N junction
When a CdTe substrate having a well region of d _X Te is etched, only the CdTe crystal is selectively etched, so that the well region projects from the substrate. Therefore, a step is formed at the boundary of the well region with respect to the surface of the substrate, the position of the well region becomes clear, and the step portion is used as an alignment mark for forming a mask for introducing impurity atoms of the opposite conductivity type. The formed mask facilitates and surely introduces impurity atoms into the well region.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

First, as shown in FIG. 1, a photoresist 12 having a predetermined pattern is formed on a CdTe substrate 11, and bromine (Br ₂ ) and methyl alcohol (CH ₃ ) are used by using the photoresist film 12 as a mask.
A groove 13 having a predetermined pattern is formed by using an etching solution composed of a mixed solution of (OH).

Then, as shown in FIG. 2, P-type Hg _1-X Cd _{X is formed} on the substrate 11.
A crystal layer 14 made of Te is formed using a liquid crystal epitaxial growth method.

Further, as shown in FIG. 3, the Hg _1-X Cd _X Te crystal layer 14 is polished to make the surface of the substrate 11 flat, and the island-shaped Hg is formed on the CdTe substrate 11.
The well region 15 of _1-X Cd _X Te is formed in a predetermined pattern.

Then, as shown in FIG. 4, the substrate 11 is treated with hydrofluoric acid (H
F), nitric acid (HNO ₃ ), acetic acid (CH ₃ COOH) and water (H ₂ O) are mixed in a weight ratio of (2-5) :( 3-5): 6: 6. Etching solution, that is, the applicant of the present invention,
Etching is carried out using the etching solution applied for in No. -191058. Then, this etching solution selectively etches CdTe and etches the Hg _1-X Cd _X Te crystal, so that the well regions 15 of Hg _1-X Cd _X Te project in island shapes as shown in FIG. A step is formed at the boundary between the well region 15 and the substrate 11.

Further, as shown in FIG. 5, a photoresist film 16 is formed on the substrate.
Then, the photoresist film 16 is formed into a predetermined pattern. When the pattern of the photoresist film 16 is formed, if the reference position of the exposure mask is aligned with the position of this step, the mask alignment can be performed accurately and easily.

Next, as shown in FIG. 6, B atoms are ion-implanted using the photoresist film 16 as a mask to form an N-type layer 17.

By doing so, the alignment mark of the mask is formed on the substrate, the alignment work becomes easy, and the semiconductor element forming pattern can be obtained with high accuracy.

〔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 mask alignment position can be easily formed.

[Brief description of drawings]

1 to 6 are sectional views showing the steps of the method for manufacturing a semiconductor device according to the present invention, and FIGS. 7 to 8 are sectional views showing the steps of the conventional method for manufacturing a semiconductor device. In the figure, 11 is a CdTe substrate, 12 is a photoresist film, 13 is a groove, and 14 is Hg.
Crystals of _1-X Cd _X Te, 15 are well regions, 16 is a photoresist film, and 17 is an N-type layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/306 B

Claims (1)

[Claims] 1. A photoelectric conversion element is formed by forming a well region made of mercury, cadmium, tellurium in a predetermined pattern on a cadmium-tellurium substrate and introducing impurity atoms of a reverse conductivity type into the well region. In the method of forming, after forming the well region, the substrate is selectively etched by a selective etching agent to project the well region from the surface of the substrate, and a cadmium tellurium crystal and a well forming the substrate are formed. Forming a step at the boundary position of the mercury-cadmium-tellurium crystal forming the region, and forming a mask for introducing impurity atoms of the opposite conductivity type into the well region on the substrate based on the position of the step Then, a method of manufacturing a semiconductor device is characterized in that a step of introducing the impurity atoms is provided using the mask.