JPH098065A - Thermal treatment method of sealed tube - Google Patents

Abstract

PURPOSE: To prevent foreign matter from sticking to a wafer or damaging it at the time of crushing of a quartz tube, in a thermal treatment method which is performed by inserting the wafer into the quartz tube. CONSTITUTION: An element wafer 2 is inserted into a quartz tube 3, and adjustment is so performed that the area of an aperture part of the quartz tube 3 is made as small as possible. The inside quartz tube 3 in which the element wafer is put is inserted into an outside quartz tube 1. After the outside quartz tube 1 is vacuumized and tightly closed by fusing, the outside quartz tube 1 is set in an electric furnace and treated by heating. After the thermal treatment is finished, the quartz tube 1 is crushed. At the time of crushing, a cutting position 4 on the opposite side of the aperture part of the inside quartz tube 3 is flawed, and the tube is crushed. At this time, atmosphere is inhaled into the quartz tube 1. Since the inside quartz tube 3 relieves the inflow of atmosphere, deposit on the surface of the element wafer 2 is remarkably reduced. Damage due to the deposit is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube heat treatment method, and more particularly to a tube for controlling electric characteristics and improving electric characteristics applied to a material for an infrared detecting element such as HgCdTe or a bolometer thin film material. The present invention relates to a heat treatment method.

[0002]

2. Description of the Related Art In a process of manufacturing an infrared detector or the like using a compound semiconductor, a heat treatment of a wafer is required for controlling electric characteristics or stabilizing the characteristics.
A conventional heat treatment method will be described with reference to FIG.
First, as shown in FIG. 2, an element wafer 2 for an infrared detector or the like is inserted into an outer heat treatment quartz tube 1. At that time, in the case of HgCdTe, an appropriate amount of mercury is inserted into the quartz tube simultaneously with the element wafer, and in the case of the bolometer thin film material, only the element wafer is inserted.

After evacuating the quartz tube 1 to a high vacuum, the tube is fusion-sealed. Thereafter, the quartz tube is mounted in an electric furnace and subjected to a predetermined heat treatment. After cooling, the quartz tube for heat treatment 1 is crushed at the cutting point 4 and the device wafer 2 is taken out. Thereafter, a predetermined process is performed on the element wafer 2 to produce an infrared detector.

[0004]

In the process of taking out the element wafer from the quartz tube, when the tube is crushed, the inside of
^-3 Torr or less vacuum, the air is sucked into the tube at a stretch, and Hg
In the case of CdTe, mercury particles, water droplets and glass fragments adhere, and in the case of a bolometer thin film material, water droplets and glass fragments adhere. Some of these deposits are removed by subsequent washing, but some remain on the element, and even when removed, adhesion marks remain, leading to deterioration of electrical characteristics and reliability. Was. Accordingly, it is an object of the present invention to prevent foreign matter from flying onto and adhering to or damage the wafer when the quartz tube for heat treatment is crushed.

[0005]

According to the present invention, there is provided a method for heat treatment of a sealed tube according to the present invention, comprising: (1) a step of arranging an object in an inner quartz tube having an opening; A step of disposing an inner quartz tube having a body inside the outer quartz tube, (3) a step of evacuating to a high vacuum, and then sealing the outer quartz tube by welding, and (4) a step of applying a predetermined heat treatment. (5) a step of crushing the outer quartz tube at a cutting position and taking out the object to be processed, wherein the cutting of the outer quartz tube in the step (5) is performed by cutting the opening of the inner quartz tube. It is characterized in that it is performed at the end opposite to the opening direction.

[0006]

When the outer quartz tube is crushed, the air is sucked into the tube from the cut point, so that the part facing the cut point is directly hit by the flying object. Thus, in the heat treatment method of the present invention, an inner quartz tube having an opening is newly provided, and a wafer to be processed is disposed therein. And the inner quartz tube is
Since the opening is arranged so as to face the side opposite to the cutting point of the outer quartz tube, the wafer placed therein has a reduced chance of being directly hit by a flying object. Also, when the outer quartz tube is crushed, the inner quartz tube serves as a buffer,
Even if a flying object collides, its impact force is weakened. Therefore, even if an attached matter is generated, the attached force is weak and can be easily removed, and the attached mark due to the attached matter becomes shallow.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a quartz tube for explaining one embodiment of the present invention. First, the element wafer 2 to be subjected to the heat treatment is inserted into the inner quartz tube 3 and shaped by a burner so as to make the opening area of the quartz tube 3 as small as possible. Next, the inner quartz tube 3 containing the element wafer is inserted into the outer quartz tube 1. At this time, a material necessary for the heat treatment is also loaded at the same time. For example, HgCd for infrared detector
In the case of a Te wafer, mercury is simultaneously inserted into the outer quartz tube 1. After the outer quartz tube 1 is evacuated and sealed by fusion welding, it is mounted on an electric furnace and heat-treated according to a predetermined program.

After the heat treatment, the quartz tube 1 for external heat treatment is crushed after waiting for natural cooling. At the time of this crushing, a cut is made on the cutting point 4 on the opposite side of the inner quartz tube 3 from the opening, and the tube is crushed. At this time, the atmosphere is sucked into the quartz tube 1,
Since the inner quartz tube 3 buffers the inflow of air, the amount of deposits on the surface of the element wafer 2 is drastically reduced. In addition, damage due to deposits is reduced. In fact, according to the present invention, the deposits and scars could be reduced to about 1/10 of the conventional case.

[0009]

As described above, according to the heat treatment method of the present invention, a heat treatment is performed by inserting a wafer to be processed into an inner quartz tube having an opening. At the cutting point opposite to the side,
Since it is crushed, it is possible to suppress attachment and damage of foreign matter on the wafer to be processed during crushing. Therefore, according to the present invention, it is possible to improve the electrical characteristics and reliability of devices manufactured using this wafer. For example, when performing a heat treatment on a wafer for an infrared detection element, a high quality camera can be provided by reducing pixel defects.

[Brief description of drawings]

FIG. 1 is a perspective view of a quartz tube for heat treatment for explaining an embodiment of the present invention.

FIG. 2 is a perspective view of a conventional heat treatment quartz tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz tube for outer heat treatment 2 Element wafer 3 Inner quartz tube 4 Cutting place

Claims (2)

[Claims] (1) a step of arranging an object to be processed in an inner quartz tube having an opening; (2) a step of arranging an inner quartz tube having an object to be processed in an outer quartz tube; (3) A step of fusing and sealing the outer quartz tube after evacuation to a high vacuum; (4) a step of applying a predetermined heat treatment; and (5) a step of crushing the outer quartz tube at a cutting location and taking out the object to be processed. Wherein the cutting of the outer quartz tube in the step (5) is performed at an end of the inner quartz tube opposite to the opening direction of the opening. Method. 2. The method according to claim 1, wherein after the step (1) is completed, prior to the step (2), a step of narrowing the opening of the inner quartz tube is inserted. Sealed tube heat treatment method.