JP2624832B2 - Anodic bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a bonding apparatus, and particularly to an anodic bonding apparatus for bonding metal and glass with good airtightness.

(Prior art) The anodic bonding apparatus known in the prior art has a temperature of 600 ° C.
Place an insulating plate in an electric furnace that can raise the temperature to the vicinity, place a plate plated with a noble metal (gold etc.) or a negative electrode plate made of a platinum plate on top of it, and place the glass to be joined on it,
Further, after the metal plate to be joined to the glass is placed, a positive potential is applied to the metal plate to be joined using an electrode plate (often platinum) or a probe that can be ohmic-connected to the metal plate to be joined.

However, in the configuration of this conventional technique, not only is the electrode material used expensive, but also, for example, when the metal plate to be connected is a semiconductor, ohmic connection with the upper positive electrode can be expected, and furthermore, at the interface between the semiconductor substrate and glass. In order to obtain a merit that a uniform potential can be applied and uniform bonding can be expected, it is necessary to provide a diffusion layer for bonding.

(Problems to be Solved by the Invention) In the configuration of the above-described conventional technology, a uniform electric field is not applied to the interface between the glass and the semiconductor substrate to be bonded, and a uniform bonding is not always obtained. . That is, the bonding area was limited to about 20 mmφ or less. In addition, if a low resistance diffusion layer is used for a semiconductor substrate in order to perform uniform bonding, the chip area is increased, which not only increases the cost but also lowers the probability of uniform bonding. Furthermore, since the electrodes to be used are exposed to a high temperature in an oxidizing atmosphere, it is often necessary to remove the oxide film in order to ensure ohmic connection with the semiconductor substrate to be joined. In addition, when a high potential is applied to a conventional metal electrode, contaminants adhering to the metal electrode may concentrate on the bonding interface and make bonding impossible. Therefore, an object of the present invention is to realize an anodic bonding apparatus that can solve the above-described disadvantages, and the object of the present invention is also there.

[Constitution of the Invention] (Means for Solving the Problems) The anodic bonding apparatus of the present invention superimposes a conductor such as a metal or a semiconductor and an insulator such as a glass, and bonds the conductor at a temperature lower than the melting point thereof. In an apparatus for joining a conductor and an insulator by applying a DC voltage with the anode and the insulator as a cathode, a positive electrode that contacts the conductor and applies a positive potential and a negative electrode that contacts the insulator. A semiconductor wafer is used as the negative electrode to apply a voltage, and a uniform uniform electric field is formed between these two semiconductor substrates at a high temperature at the time of bonding, and the substrate material is stable due to its high purity and flatness. It becomes possible to arrange the configuration in a manner as described above.

(Operation) In the anodic bonding apparatus of the present invention, even when the semiconductor substrate wafer (often a silicon wafer) has a high resistance at room temperature, electrons are thermally excited to become a conductor at a bonding temperature, and the semiconductor substrate wafer is extremely clean. It becomes an electrode with a good conductivity. Therefore, the potential provided by the high voltage power supply becomes uniform over the entire semiconductor substrate wafer. Furthermore, even if an oxide film is formed on the wafer surface at a high temperature, for example, at a high voltage and a high temperature, an unstable potential distribution does not occur due to insulation by the formed oxide film. Even if the formed oxide film becomes thick and needs to be removed, the silicon oxide film is removed in a clean state with ammonium fluoride or the like.

(Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIG. 1 shows an anodic bonding apparatus according to one embodiment of the present invention. First
As shown in the figure, in the anodic bonding apparatus of this embodiment, a heater (2) is provided below a bottom surface of a vacuum chamber (1), and a negative electrode terminal (3a) is provided on an upper surface of the vacuum chamber (1) via a hermetic. , A positive electrode terminal (3b). Also,
The vacuum chamber (1) is provided with a nozzle (4) for drawing a vacuum.

An insulating glass plate (5) is placed on the bottom surface in the vacuum chamber (1), and a positive electrode (6) made of a 5-inch silicon wafer for applying a positive potential (earth potential is safe) is placed thereon. It has been placed. The metal to be bonded (7) is placed on the positive electrode (6) with the surface to be bonded facing up,
The glass to be bonded (8), for example, Pyrex glass, is processed on the mirror surface, and the bonding location is determined by an alignment device (magnifying glass) and installed. A negative electrode (9) made of a 4-inch silicon wafer is placed on the glass to be joined (8), and the weight of the negative electrode (3a) connected to the negative electrode terminal (3a) is placed on the negative electrode (9). 10a). Similarly, a positive electrode weight (10b) connected to the positive electrode terminal (3b) is placed on the positive electrode (6). The anodic bonding apparatus having the above-described configuration can easily achieve the insulating property and the cleanness for applying a high potential, though it is simple.

In the anodic bonding apparatus according to one embodiment of the present invention configured as described above, the positive electrode (6) made of a silicon wafer is used.
In the region sandwiched between the negative electrode (9) and the silicon wafer, a uniform electric field is formed over a wide area, and the insulating glass plate (5) used for insulation is smaller than the bonding area. ) Is transmitted from the center, so that the joining also proceeds from the center and spreads throughout. Since the positive electrode (6) and the negative electrode (9) are made of a silicon wafer, the silicon wafer has a uniform surface at the interface to be joined due to its high purity, flatness, mechanical strength, and good conductivity at high temperatures. Since a stable electric field can be applied for a long time, a highly reliable junction can be achieved in a wide area. Further, since the material used satisfies the cleanliness as a semiconductor material, impurities which are easily mixed during joining can be reduced as much as possible, and a highly airtight joining can be obtained. After further evacuation, the inside of the chamber (1) is replaced with oxygen, whereby a more reliable bonding can be obtained. If the chamber (1) is filled with an appropriate atmosphere gas and anodic bonding is performed, an application device in which the cavity provided in the bonding interface is filled with the intended gas at the intended partial pressure can also be manufactured.

[Effects of the Invention] As described above in detail, according to the present invention, a conductor such as a metal or a semiconductor and an insulator such as glass are overlapped, and the conductor is used as an anode at a temperature lower than the melting point of the conductor. In a device for joining a conductor and an insulator by applying a DC voltage with a negative electrode, a positive electrode that contacts the conductor and applies a positive potential and a negative electrode that contacts the insulator and applies a negative potential Realization of an anodic bonding device using a semiconductor substrate for a long time, stable uniform electric field at the interface to be bonded for a long time due to high purity, flatness, mechanical strength and good conductivity at high temperature of the semiconductor substrate. , A highly reliable junction can be achieved over a large area. In addition, since the material to be used satisfies the cleanliness as a semiconductor material, impurities easily mixed in at the time of bonding can be reduced as much as possible, and a high-quality air-tight bonding can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an anodic bonding apparatus according to one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber, 2 ... Heater, 5 ... Insulating glass plate, 6 ... Positive electrode, 7 ... Metal to be joined, 8 ... Glass to be joined, 9 ... Negative electrode

Claims (1)

(57) [Claims] 1. A conductor such as a metal or a semiconductor and an insulator such as glass are superimposed on each other, and a DC voltage is applied by using the conductor as an anode and the insulator as a cathode at a temperature lower than their melting points. An anode, wherein a semiconductor substrate is used as a positive electrode which contacts the conductor to apply a positive potential and a negative electrode which contacts the insulator and applies a negative potential. Joining equipment.