JPH0626238B2 - Bonding method for semiconductor device substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for adhering a substrate for a semiconductor device, and sometimes to a method for adhering a substrate for a semiconductor device, which is suitable for manufacturing a substrate for a multilayer structure device.

[Problems to be Solved by Prior Art and Invention]

As a conventional method for adhering substrates of this kind, fusion with a low melting point glass or adhesion with an organic material such as a polyimide resin has been a main method, but the low melting point glass has a softening point (usually 800).
Since the organic material becomes physically unstable at temperatures above the melting point (usually below 600 ° C.) at temperatures above (° C.) and above, there is a problem in that the adhesive strength is significantly reduced in both cases. Therefore, it cannot be used in a manufacturing process of a multi-layer structure device that requires a temperature of 1000 ° C. or higher such as epitaxial growth, diffusion, and heat treatment after the bonding process. That is, in the conventional substrate bonding method, i) a semiconductor substrate and a semiconductor substrate (which may be a metal substrate or an insulating substrate) are bonded together and then polished, which is a so-called reverse epitaxial method. SOI placed
(Semiconductor on Insulator) substrate or ii) It is manufactured by bonding two kinds of semiconductor substrates with different characteristics,
After that, the OEIC (Opto placed under high temperature at the time of element formation
A three-dimensional optical circuit (planar optical information can be processed) that is manufactured by bonding a substrate for electrical IC) and iii) a substrate incorporating an optical switch etc. in multiple layers and then placed under high temperature when forming the circuit. It has been impossible to manufacture a substrate for a multi-layered structure device such as a substrate for a circuit).

In view of the above problems, it is an object of the present invention to provide a method for adhering a substrate for a semiconductor device, which enables production of a substrate for a multi-layered structure device.

[Means and Actions for Solving Problems]

The method for adhering a semiconductor device substrate according to the present invention is
A metal oxide sol obtained by hydrolyzing a metal alkoxide containing any one of Al, Ti, and Pb, or a liquid substance obtained by gelling the same is used, and the liquid substances are interposed between a plurality of substrates to attach them to each other. Then, a group of these bonded substrates is subjected to a high temperature treatment at 500 ° C. or higher to form a high heat resistant adhesive layer between the substrates.

The steps are shown below.

(1) Metal alkoxide M (OR) n (where M is S
i, Al, Ti, Pb, R is CH ₂ , C ₂ H ₅ ,
C ₃ H ₇ , and n is 1, 2, 3, ... ) Is hydrolyzed in a solvent such as alcohol to prepare a sol-state solution. Alternatively, a commercially available metal oxide sol such as silica sol or alumina sol may be prepared.

(2) Apply the solution to the surface of the substrate to be bonded. The solution may be simply dropped, or a brush, a roller or the like may be used, but in order to apply the solution uniformly, a spray method, a spin coating method or a combination of both methods is preferable.

(3) The solution is left at a temperature of less than 150 ° C. to proceed with dehydration condensation reaction and desolvation to semi-gelate. In this step, the solution is semi-dried and semi-desorbed in advance, and the pore size in the produced gel is made small to facilitate the heat treatment step after adhesion. However, this is not a prerequisite for bonding. Also, low temperature,
The longer the time, the better, but practically it is sufficient to carry out the semi-gelation at 60 ° C. for 30 minutes. When gelled at a temperature of 150 ° C. or higher, the pore size becomes large, and sufficient sintering cannot be performed under the sintering treatment conditions described later.

(4) The substrates are adhered to each other and heated to 150 ° C. or more while applying a pressure of 1 kg / cm ² or more to dehydrate and condense the gel of the adhesive layer and simultaneously form a bridge between both substrates. When the temperature is raised to 150 ° C or higher, the decomposition peak of residual organic matter is 150 ° C.
Since it exists above, by experiencing this process
This is for the purpose of decomposing and removing the residual organic substances that could not be removed in (3) and for promoting the evaporation of the water generated by the dehydration condensation reaction. Removal of these residues and products is effective in reducing cracks in the adhesive layer later. The dehydration condensation reaction itself gradually progresses from room temperature to almost 500 ° C.

(5) The temporarily bonded substrates are heat-treated at a high temperature to sinter to make them non-porous. The processing temperature is 500 ° C. or higher and the time is 2 hours. If the temperature is 500 ° C. or lower, the non-pore formation is incomplete and the strength is insufficient. The effect of this step is to make the adhesive layer strong and stable.

A substrate for a multilayer structure device having a highly heat resistant adhesive layer is formed by the above 5 steps.

Incidentally, a method of simply synthesizing a metal oxide using a metal alkoxide as a starting material has been widely performed as a so-called sol-gel method until now, but the metal oxide is used as an adhesive layer under the condition of being sealed in an adhesive surface. There is no example of forming it.

When a metal oxide sol is used, the same treatment as in (2) above may be performed. Further, when three or more substrates are adhered, a metal oxide sol may be applied to each adhering surface, and thereafter the same treatment may be performed.

[Example 1] An example will be described in which a solution of tetraethoxysilane hydrolyzed with hydrochloric acid as a catalyst is used as an adhesive to bond silicon single crystal substrates having a diameter of 50 mm. The drawing is a program diagram of the pressure heating process. The conditions of each step are as follows.

Step (1) Ethanol 75, water 75, and 1N hydrochloric acid 0.5 were mixed in a volume ratio to 100-tetraethoxysilane and stirred. If the water content is 75 or less relative to 100 parts of ethoxysilane, cracks are likely to occur in the subsequent process. 7 for 75 water
With ethanol of 5 or less, the mixed solution undergoes two-phase separation. The reaction is possible even if water and ethanol above the above are added to tetraethoxysilane, but more time is required for the subsequent drying step. Hydrochloric acid is not essential.

Step (2)-The solution is applied to the substrate surface by a spinner.
For example, when the spinner is rotated at 5000 rpm for 15 seconds, a coating layer of 2000 Å or less can be uniformly formed.

Step (3)-The substrate is heat-treated at 100 ° C. for 15 minutes.

Step (4)-30 at 280 ° C. while applying pressure of −3 kg / cm ^2.
Heat treat for minutes.

Step (5): Heat treatment is performed at −800 ° C. for 30 minutes.

In the case of this example, the mounting layer is made of quartz glass, and the bonded state of the substrate is maintained up to just below the melting point of silicon.

[Example 2] Step (1) -Ethanol 75, water 60, 1N hydrochloric acid 0.1% by volume ratio to 100 parts of aluminum i-butoxide.
Mix 5 and stir.

Step (2)-same as (2) of Example 1.

Step (3) -same as (3) of Example 1.

Step (4)-same as (4) of Example 1.

Step (5)-same as (5) of Example 1.

In this case, the adhesive layer is alumina, and the adhesive state is maintained just below the melting point of silicon.

Adhesion of a silicon single crystal substrate and a quartz substrate or a silicon single crystal substrate and a potassium arsenide substrate by the same method as above,
Lithium niobate substrates can also be bonded.

〔The invention's effect〕

As described above, the method for adhering a substrate for a semiconductor device according to the present invention makes it possible to manufacture a substrate for a multilayer structure device having a high heat resistant adhesive layer, and as a result, it is used for a conventional single structure substrate. The element manufacturing technology that requires a high temperature of 1000 ° C. or higher can be used as it is for the multilayer structure substrate, and there is an advantage that various multifunctional elements such as SOI, OEIC, and three-dimensional optical circuit can be manufactured.

[Brief description of drawings]

The drawing is a program diagram of the pressure heating process of one embodiment of the method of the present invention.

Claims (1)

[Claims] 1. A metal oxide sol obtained by hydrolyzing a metal alkoxide containing any one of Si, Al, Ti, and Pb, or a liquid material obtained by gelling the metal oxide sol, and using the liquid material between a plurality of substrates. For a semiconductor device in which objects are bonded to each other and then a group of these bonded substrates is subjected to a high temperature treatment of 500 ° C. or higher to form a high heat resistant adhesive layer between the substrates. Substrate bonding method.