JPH025545A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device whose silicon is uniform in thickness by a method wherein a silicon dioxide and polysilicon are deposited on the surface of a first silicon substrate after a groove has been provided to the face of the silicon substrate, the above face is pasted onto a second substrate, the first substrate is abraded until the silicon dioxide is exposed, and a semiconductor element is formed on the abraded face. CONSTITUTION:An oxide film of silicon dioxide is formed on a primary face of a first silicon substrate 1 after a groove has been provided, then the groove is filled with a polysilicon 3, and the polysilicon 3 is abraded to be flat. Then, the first substrate 1 is pasted onto a second silicon substrate 4, which are chemically compounded, and the silicon substrate 1 is selectively abraded from the rear until the oxide film 2 inside the groove is exposed. As amine is used as an abrasive solution, the abrasion stops automatically when the oxide film 2 is exposed. Therefore, the thickness of a silicon layer becomes nearly equal to the depth of the groove, so that the silicon layer with uniform thickness can be precisely formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a semiconductor device.

The present invention relates to a method of manufacturing a semiconductor device having a dielectric isolation structure.

[Conventional technology]

Conventionally, as a method for manufacturing a semiconductor device having a dielectric isolation structure, there has been a method of forming a semiconductor element using island-shaped silicon provided on a sapphire substrate.
n5apphire, abbreviated as SOS), a method in which oxygen ions are implanted into a silicon substrate, and then a silicon layer is evixtally grown, and this silicon layer is formed into an island shape to form a semiconductor element there (Saparal, ion by Im).
(abbreviated as SIMOX)
etc. were known. However, in SO3, the crystallinity of the silicon layer is poorer than that of normal bulk silicon;
It has the disadvantage of low mobility of electrons and holes, and S T
, MOX requires a large amount of oxygen to be ion-implanted, and the disadvantages are that the shape of the substrate is difficult.
It has been reported that a semiconductor device with a dielectric isolation structure can be formed by using two silicon substrates, forming an oxide film on the surface of at least one of the substrates, and bonding the two plates together with an oxide film in between. This technology is being used
Since crystalline silicon can be used to form semiconductor devices, there is no decrease in mobility as seen in SO5, and the bonding process requires only heat treatment and voltage application.
It has the advantage of not requiring a large amount of ion implantation in MOX.

[Problem to be solved by the invention]

However, in this bonding technology, it is important to form a thin silicon layer to form a semiconductor element, but it has been difficult to easily form a thin silicon layer with good control using previously reported methods. . For example, a method of reducing the thickness by polishing is inexpensive, but it is difficult to obtain a uniform silicon layer with high precision. It is also known to create a semiconductor element forming layer by thinning silicon by selective etching using an epitaxial wafer, but this method has the drawback that the cost of the epitaxial wafer is high.7Objects of the present invention It is an object of the present invention to provide a method for manufacturing a semiconductor device, which eliminates the drawbacks of deviance 1:' and can form a silicon layer of uniform thickness with high precision without significantly increasing the number of steps.

[Social means to solve problems]

In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention includes a step of forming a silicon dioxide on the surface of the silicon after forming a groove on one main surface of the first silicon substrate, and a step of forming silicon dioxide on the surface of the silicon. a step of forming 4X' polysilicon on one main surface of the substrate, filling the above-mentioned grooves, and then polishing the polysilicon to flatten the surface; a step of laminating the drawing board by adhering the two silicon substrates closely and applying heat treatment; a step of selectively polishing the first silicon substrate from the other main surface until the silicon dioxide formed at the bottom of the groove is exposed; The method includes a step of forming a semiconductor element on the polished surface of the first silicon substrate.

[Effect]

If an amine-based polishing liquid is used for polishing the wafer in the method for manufacturing a semiconductor device of the present invention in step 19, the polishing speed of the silicon oxide film is as low as 1/100 or less compared to the polishing speed of silicon, and the oxide film Polishing stops at the point where is exposed. Therefore, when silicon is selectively polished by forming a silicon oxide region in advance in silicon, the polishing stops when this silicon oxide is exposed, and the silicon surrounded by silicon oxide has a constant thickness. It is formed.

Therefore, silicon can be polished to a constant thickness with high precision just by polishing.

〔Example〕

An embodiment of the method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIGS. 1-4. Figures 4 and 4 show cross sections of a portion of the wafer in each manufacturing process.

First, as shown in FIG. A trench whose surface is covered with an oxide film 2 made of silicon dioxide fc is formed on the main surface of a silicon substrate 1. Specifically, after a groove is formed on the main surface of the first silicon substrate 1 by anisotropic dry etching, an oxidized pattern 2 is formed inside the groove by thermal oxidation, and then polysilicon 3 is etched. The grooves are filled and the polysilicon is polished to make the surface flat. Next L: As shown in FIG. 2, the first silicon substrate 1 and the second silicon substrate 4 are bonded together and chemically bonded by heat treatment.

In this step, for example, after the two silicon substrates described above are subjected to hydrophilic treatment, the adhesion is maintained at a high temperature (for example, 1150°C
) by heat treatment. This method
- It is called a le junction and is reported, for example, in Oyoi Physics, Vol. 56, No. 3, pp. 373-376 (1987).

It is also possible to bond with an oxide film in between,
This method can be used, for example, at International Ellen 1-Ron Device Meeting CIEE.
E, Hinternational El, eetro
n I)evic.

Technical Digest h (T
eehriieatDi (Hest) pp. 684-687 (1985). A similar technique is also reported in Japanese Patent Publication No. 3947869. Third
In the figure, next, by selectively polishing the first silicon substrate 1- from the back surface, the enamel 11λ provided at the bottom of the
Polish until 2 is exposed.

By using amine as the polishing liquid, polishing automatically stops when the oxide film 2 is exposed, so the thickness of the first silicon substrate 1- after polishing is approximately equal to the depth of the groove described above. , <, and a silicon layer of uniform thickness can be formed with high precision. Thereafter, as shown in FIG. 3, the silicon layer 11, which is part of the silicon substrate 1-, is dielectrically separated
As shown in Figure 4, 1 silicon 7, n'''' silicon 8 silicon 9.9 silicon 1
Form O, goo 1-oxide film 5. By attaching a gate electrode 6 and configuring a semiconductor element, a dielectrically isolated semiconductor device can be obtained. () Let it go. Figure 71 shows a complementary HlFET (Insulated Gate).
Field, d Effect Transj, 5
This is an n-channel IGFET with a 1-electrode 6 made of polysilicon.
, 1. P-channel IGFETs are formed dielectrically isolated from each other.

〔Effect of the invention〕

As explained below, according to the present invention, surface flattening is easy due to the use of polysilicon, and it can be easily manufactured using the technique of bonding a silicon wafer to a single conductor substrate separated by a dielectric. This method has the advantage of being able to form dielectrically isolated silicon of uniform thickness and precisely contoured.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of a portion of a first semiconductor wafer showing an embodiment of the present invention in the order of steps. ]--First silicon substrate 2...Oxide film: U-
...Polysilicon 4...Second silicon substrate 5
...Gate/oxide film 6...Ge-1-electrode 7...p0 silicon 8...n+silicon 9...n silicon 10...■) Silicon】l...Silicon layer

Claims (1)

[Claims] (1) After forming a groove on one main surface of the first silicon substrate, forming silicon dioxide on the surface of this silicon, and forming polysilicon on one main surface of this silicon substrate to fill the above groove. Thereafter, a step of polishing the polysilicon to flatten the surface, a step of adhering one main surface of the first silicon substrate and a second silicon substrate to each other by applying heat treatment, and a first step. a step of selectively polishing the silicon substrate from the other main surface until silicon dioxide formed at the bottom of the groove is exposed; and a step of forming a semiconductor element on the polished surface of the first silicon substrate. A method of manufacturing a semiconductor device, comprising: