JPH0515453U - SOI substrate - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an SOI substrate capable of improving stress relaxation and device characteristics caused by bonding. In an SOI substrate formed by directly joining two Si wafers, the first Si wafer having a refractory metal or refractory metal silisite formed on one surface serving as a bonding surface is bonded to the first Si wafer. After forming SiO2 on one of the surfaces, the second Si wafer having the refractory metal formed on the upper layer of SiO2 and the bonding surface at 800.degree.
It is characterized by being integrally joined by the above heat treatment.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an SOI (Silicon On Insulator) substrate formed by directly bonding two Si wafers, and in particular, relaxes stress generated during bonding.

[0002]

[Prior Art]

 As an SOI substrate formed by directly bonding two Si wafers, conventionally, two Si wafers are directly bonded via SiO2. For example, as a bonding condition, 1000 ° C, Joining is performed by annealing for 30 minutes.

However, in such bonding, stress is generated due to the difference in thermal expansion between Si and SiO 2 when heat treatment is performed at a high temperature, which causes warpage of the Si wafer and adversely affects the characteristics of the element. There were issues such as bringing.

[0004]

[Problems to be solved by the device]

 The present invention has been made in view of the above problems of the prior art, and relates to a direct-bonded SOI substrate, by forming an intermediate layer of silisite at the interface between Si and SiO2, the thermal expansion of Si and SiO2 is prevented. The purpose of the present invention is to provide an SOI substrate capable of relaxing the stress generated by the difference and improving the characteristics of the device.

[0005]

[Means for Solving the Problems]

 In the structure of the present invention for solving the above-mentioned problems, in an SOI substrate formed by directly bonding two Si wafers, a refractory metal or refractory metal silicite is formed on one surface to be a bonding surface. The first Si wafer and the second Si wafer having the refractory metal formed on the upper surface of the SiO2 after forming SiO2 on one surface to be the bonding surface, It is characterized by being integrally joined by heat treatment at a temperature of ℃ or more.

[0006]

[Action]

 According to the present invention, the structure of the SOI substrate has an intermediate layer of silicite formed at the interface between Si and SiO2. Therefore, the intermediate layer of silisite can alleviate the stress generated by the difference in thermal expansion between Si and SiO2, and has a bonding force similar to that of bulk Si.

[0007]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. 1A to 1D are views showing a manufacturing process and a sectional structure of an SOI substrate of the present invention. In FIG. 1, as shown in FIG. 1A, the first Si substrate has a high surface such as Ta (tantalum), Mo (molybdenum), or W (tungsten) on one side that is a bonding surface of the Si wafer 1a. The melting point metal 2a is formed to have a thickness of, for example, about 0.1 μm. The first Si substrate is annealed in a N2 atmosphere at a temperature of about 800 DEG C. to 1000 DEG C. to form silicite to form a high melting point metal silicite 3 on the surface of the Si wafer 1a. Further, as shown in (b), the second Si substrate has a thickness of about 1 to several layers of SiO 2 4 for dielectric isolation and insulation of the element on one side surface which is a bonding surface of the Si wafer 1b. After being formed to a thickness of about μm, a refractory metal 2b such as Ta (tantalum), Mo (molybdenum) or W (tungsten) similar to the refractory metal 2a of the first Si substrate is formed on the SiO2 4, for example. The thickness is about 0.1 μm. As shown in (c), the refractory metal silicite 3 side (first Si substrate) and the refractory metal 2 are replaced by the refractory metal 2 and the first and second Si substrates shown in (a) and (b). The b-side (second Si substrate) is brought into contact with each other, and they are superposed and heat-treated at about 800 to 1000 ° C. for several tens of seconds to several tens of minutes to bond them.

Here, as shown in FIG. 2D, the interface between the Si wafers 1 a and 1 b after the heat treatment bonding has a high melting point metal silicite layer 3 and a Si-M (high The intermediate layer 5 made of (melting point metal) -O is formed. Therefore, from the Si wafer 1a to the Si wafer 1b, the bonding interface forms an intermediate layer in which components are continuously distributed.

As described above, the intermediate layers 3 and 5 shown in FIG. 1D have the same adhesive force as that of bulk Si, can alleviate the stress generated by the difference in thermal expansion, and have a high melting point. The structure of the SOI substrate having the metal silicite layer 3 and the resistivity of the refractory metal silicite layer 3 is 10 ⁻⁴ Ωcm or less, and having the buried layer capable of reducing the parasitic capacitance and speeding up the device. Can be formed.

[0010]

[Effect of the device]

 As described above in detail with the embodiments, the present invention has the structure of the SOI substrate in which the intermediate layer of silicite is formed at the interface between Si and SiO 2. Therefore, the intermediate layer of silicite can realize the SOI substrate which can alleviate the stress generated by the difference in thermal expansion between Si and SiO2 and improve the element characteristics such as the parasitic capacitance reduction and the device speedup.

[Brief description of drawings]

FIG. 1 is a view showing a manufacturing process and a sectional structure of an SOI substrate of the present invention.

Claims (1)

[Scope of utility model registration request] 1. An SOI substrate formed by directly bonding two Si wafers together with the first Si wafer having a refractory metal or refractory metal silicite formed on one surface to be a bonding surface. , SiO2 is formed on one surface to be the bonding surface,
2 above the second Si having the refractory metal formed on it.
An SOI substrate, which is formed by integrally bonding a wafer and the bonding surface by heat treatment at 800 ° C. or higher.