JPH0574667A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device manufacturing method which can manufacture an SOI device provided with buried diffusion layers without making epitaxial growth. CONSTITUTION:An SOI substrate provided with buried diffusion layers 5 and 6 and a positioning mark 3 is manufactured by sticking a semiconductor substrate 1, on which the impurity diffusion layers 5 and 6 and positioning mark 3 and an insulating film 7 coating the surface of the substrate 1 including the layers 5 and 6 and mark 3 are formed in advance, to a supporting substrate 8 with the film 7 in between and grinding the substrate 1 to a desired thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More specifically, the present invention relates to a method of manufacturing an SOI device having a buried diffusion layer.

[0002]

2. Description of the Related Art Conventionally, in manufacturing an SOI device having a buried diffusion layer, as shown in FIG.
2 on which the element substrate 24 is positioned with the insulating film 23 interposed therebetween.
After producing the I substrate 21 (FIG. 2A), impurity diffusion is performed to form diffusion layers 25, 26 and 27 (FIG. 2B).
The epitaxial layer 28 was grown on the element substrate 24 (FIG. 2C) to form the buried diffusion layers 30, 31, 32.

[0003]

The conventional method is a method requiring a long manufacturing time and a high manufacturing cost because it is necessary to utilize the epitaxial growth for forming the buried diffusion layer as described above. It was

An object of the present invention is to provide a method capable of manufacturing an SOI device having a buried diffusion layer without performing epitaxial growth.

[0005]

According to a method of manufacturing a semiconductor device of the present invention, an impurity diffusion layer and a recess are formed in a semiconductor which is to constitute an element substrate of an SOI substrate, and the surface thereof is oxidized to leave the remaining space. Is formed in advance, and an insulating film having an appropriate film thickness is formed on the surface on which these are formed, and then the semiconductor is bonded to a supporting substrate through the insulating film, This semiconductor device is characterized by including a step of grinding this semiconductor to a desired thickness to form an element substrate and producing an SOI substrate having a buried impurity diffusion layer and an alignment mark.

In the method of the present invention, an SOI substrate is manufactured by utilizing the bonded SOI technology. That is, an impurity diffusion layer and an alignment mark are formed on the element substrate side in advance, and this element substrate is attached to a supporting substrate via an insulating film to manufacture an SOI substrate.

Impurities such as arsenic (As), antimony (Sb), and boron (B) in a diffusion layer formed in advance in a semiconductor such as silicon which constitutes an element substrate are ion-implanted or solid-phase diffused. Alternatively, it can be diffused by any known method such as a vapor phase diffusion method. Impurities in the diffusion layer are further diffused at the time of heating for bonding the element substrate and the supporting substrate, which will be described later. Therefore, the diffusion layer formed in advance should be formed in consideration of this fact.

The alignment mark is formed by forming a recess in the semiconductor that should form the device substrate, oxidizing the surface of the recess, and filling the remaining space. The concave portion is a V-shaped groove (effective for a silicon semiconductor) that can be formed by etching with an aqueous potassium hydroxide solution, or a U-shaped groove that can be formed by anisotropic etching. Good. The depth of the concave portion to be formed is the surface of the element substrate ground to a desired thickness in the completed SOI substrate,
The depth is such that the identifiable tip portion of the recess of the alignment mark (which corresponds to the bottom portion of the recess) is exposed. The depth of the concave portion depends on, for example, the width of the resist opening when forming a V-shaped groove by etching with an aqueous solution of potassium hydroxide, or by U by anisotropic etching.
When forming the V-shaped groove, it can be easily adjusted depending on the etching time.

The recess thus formed oxidizes the surface to form an oxide film thereon. If this oxide film is made thick, a large stress may be generated, which may cause damage, and if it is made thin,
There is a possibility that the semiconductor of the element substrate and the material filling the space of the recess are locally connected to change the capacitance. Therefore, for example, in the case of a silicon semiconductor, it is generally 200
It is suitable to be about 0 to 4000Å, preferably around 3000Å.

The space of the concave portion of the alignment mark which is oxidized to form an oxide film on the surface can be conveniently filled with, for example, polysilicon.

The impurity diffusion layer and the alignment mark formed on the semiconductor that constitutes the element substrate may be formed in any order. When the alignment mark is formed first, the position of the diffusion layer to be formed later can be determined with this mark as a reference.

As mentioned above, in the method of the present invention, the surface of the semiconductor on which the diffusion layer and the alignment mark are previously formed is bonded to the supporting substrate through the insulating film by using the bonding SOI technique. .. Therefore, an insulating film having a thickness effective as an insulating film of the SOI substrate must be provided on the semiconductor surface on which the diffusion layer and the alignment mark are formed. For an insulating film such as a silicon oxide film, after the diffusion layer and the alignment mark are formed, the insulating film with an excessive thickness on the semiconductor is ground,
Alternatively, if the thickness is insufficient, it can be compensated for to obtain the required thickness. It goes without saying that the surface of the insulating film, which is prepared to be bonded to the supporting substrate, should be flat with no steps or the like in order to sufficiently adhere it to the supporting substrate. The support substrate and the semiconductor for the element substrate are
Contact both of them and, for example, at a temperature of about 1100 ° C., about 2
By heating for a time, it can be conveniently laminated.

The semiconductor bonded to the support substrate can be ground to a thickness required for the element substrate to form the element substrate. Grinding or polishing of a semiconductor can be performed by an etching method, an abrasive method, or the like.

On the ground surface of the element substrate, the oxide of the tip portion of the concave portion of the alignment mark (that is, the portion toward the bottom of the concave portion) is exposed. The exposed oxide can be easily distinguished from the surrounding semiconductor by inspection with a microscope or the like, and serves as a reference mark for alignment in subsequent steps (diffusion, etching, etc.) for manufacturing an SOI device. Can be used.

[0015]

After the insulating film having an appropriate thickness is formed on the surface of the semiconductor on which the impurity diffusion layer and the alignment mark are formed in advance, the semiconductor is attached to the supporting substrate through the insulating film. Enables embedded SOI substrates to be fabricated without epitaxial growth.

The oxide film formed on the surface of the recess formed in the semiconductor that constitutes the element substrate of the SOI substrate is exposed on the surface of the element substrate by laminating the semiconductor with the support substrate and then grinding. , Becomes distinguishable from the surrounding semiconductors, thereby serving as a mark for alignment of subsequent steps of manufacturing an SOI device. When a buried diffusion layer is formed by utilizing epitaxial growth as in the conventional method, an insulating film on which an epitaxial film does not grow is left on it, and this insulating film is grown as an epitaxial film to form a buried diffusion layer. It can be used as an alignment mark in a later process. However, in the case of the present invention in which the buried diffusion layer is formed by using the bonding SOI technique, the surface of the element substrate is a surface formed by grinding the semiconductor to an appropriate thickness after bonding, Nothing remains that can be used as an alignment mark. Therefore, the oxide, which is exposed on the surface after grinding and is identifiable from the surrounding semiconductor, effectively acts as an alignment mark in the subsequent manufacturing steps of the SOI device.

[0017]

Next, the present invention will be further described with reference to one example. As shown in FIG. 1A (note that this figure shows a device substrate that is ready to be attached to a supporting substrate later), an area of exposed silicon is formed at a position where an alignment mark is to be formed. Resist is applied leaving KOH
Etching was performed with an aqueous solution to form a V-shaped groove 2 having a depth of about 2 μm in the silicon 1 for element substrate. On the surface of this groove, silicon oxide film 3 of about 3000 Å is formed by thermal oxidation.
Formed. The resist was removed, and polysilicon was deposited on the entire surface to fill the space of the groove 2 and then etched back to remove excess polysilicon, leaving the polysilicon 4 in the space of the groove 2.

Next, p-type and n-type impurity diffusion layers were formed on the element substrate silicon 1 in a pattern matching the alignment marks of the silicon oxide film 3. p-type diffusion layer 5
Is 1 × 10 ¹⁴ / with an acceleration energy of 60 keV
The n-type diffusion layer 6 was formed by implanting cm ³ ions, and arsenic was implanted by 5 × 10 ¹⁵ / cm ³ ions with an acceleration energy of 70 keV.

On the surface of the silicon on which the alignment mark of the silicon oxide film 3 and the impurity diffusion layers 5 and 6 are formed, the SOI is formed.
A flat silicon oxide film 7 having a thickness of 1 μm, which is effective as an insulating film on the substrate, was formed.

As shown in FIG. 1B, the element substrate 1 is brought into close contact with the support substrate 8 through the oxide film 7 and heated at a temperature of 1100 ° C. for 2 hours to separate the element substrate 1 and the support substrate 8 from each other. Perfectly stuck together.

Next, as shown in FIG. 1C, the element substrate 1 was ground to a desired thickness (about 2 μm) to expose the alignment mark 3. Then, the periphery of the element substrate was ground to finish the SOI substrate.

Using the SOI substrate having the buried diffusion layer and the alignment mark thus manufactured, the subsequent steps such as diffusion and etching were performed, and the desired SOI device could be manufactured.

[0023]

As described above, according to the method of the present invention, the buried diffusion layer and the reference for alignment in the subsequent steps such as diffusion and etching can be performed without performing the time-consuming and expensive epitaxial growth. An SOI substrate having a buried diffusion layer can be manufactured by manufacturing an SOI substrate having an alignment mark that can be used as a substrate.
That is, according to the method of the present invention, an SOI device having a buried diffusion layer can be manufactured easily and in a shorter time than that in which epitaxial growth is performed. Manufacturing costs can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of a method for manufacturing a semiconductor device of the present invention, in which FIG. 1 (a) shows alignment marks, an impurity diffusion layer, and a silicon oxide film forming an insulating film of an SOI substrate. It is a cross-sectional view showing an element substrate, (b) is a cross-sectional view showing a state where the element substrate is bonded to a supporting substrate through a silicon oxide film, and (c) is finished by grinding silicon of the supporting substrate. FIG. 6 is a cross-sectional view showing an SOI substrate with an alignment mark exposed.

FIG. 2 is a diagram illustrating a conventional method of manufacturing an SOI substrate having a buried diffusion layer by utilizing epitaxial growth, in which (a) is an SOI substrate in which an element substrate is located on a supporting substrate via an insulating film. And (b) is a sectional view showing an SOI substrate on which an impurity diffusion layer is formed,
(C) is a sectional view showing an SOI substrate in which an epitaxial layer is grown on silicon of an element substrate to form a buried diffusion layer.

[Explanation of symbols]

 1 ... Silicon for element substrate 3 ... Alignment marks 5, 6 ... Impurity diffusion layer 7 ... Silicon oxide film 8 ... Support substrate

Claims (4)

[Claims] 1. An impurity diffusion layer (5, 6) is formed in a semiconductor (1) which is to constitute an element substrate of an SOI substrate, and a recess is formed and the surface is oxidized to fill the remaining space. The alignment mark (3) is formed in advance, an insulating film (7) having an appropriate film thickness is formed on the surface on which the alignment mark (3) is formed, and then the semiconductor (1) is attached via the insulating film (7). The semiconductor substrate (1) is bonded to the supporting substrate (8), and the semiconductor substrate (1) is ground to a desired thickness to form an element substrate.
6) A method of manufacturing a semiconductor device, which includes a step of manufacturing an SOI substrate having an alignment mark (3). 2. The method according to claim 1, wherein the concave portion of the alignment mark is a V-shaped groove or a U-shaped groove. 3. The method according to claim 2, wherein the V-shaped groove is formed by etching with an aqueous potassium hydroxide solution. 4. The method according to claim 2, wherein the U-shaped groove is formed by anisotropic etching.