CN1133760C - A graphite boat with a mother liquid removal device for the growth of mercury cadmium telluride liquid phase epitaxial thin film materials - Google Patents

Abstract

The invention discloses a graphite boat with a mother liquid removal device for the growth of mercury cadmium telluride liquid phase epitaxial thin film materials, comprising: a bottom plate, a slider and a base for fixing the bottom plate and the slider, a hole is opened on the bottom plate, and the hole is built in There is a quartz spacer to adjust the height of the substrate and the opening of the hole, and the substrate is placed on the quartz spacer. There is a channel for placing the mother liquid on the slider. Its characteristic is that there are two small rectangular grooves on the surface of the slider that is in contact with the bottom plate behind the channel. The length direction of the small grooves is perpendicular to the moving direction of the slider. , the small groove collects the mother liquor remaining on the epitaxial film after the growth of the epitaxial film is completed through the movement of the slider. The device can grow a HgCdTe liquid phase epitaxial layer with a surface as bright as a mirror and without liquid, and the device is also suitable for removing residual mother liquid on the liquid phase epitaxial layer of II-VI or III-V compound semiconductors.

Description

A graphite boat with a mother liquid removal device for the growth of mercury cadmium telluride liquid phase epitaxial thin film materials

Technical field

The invention relates to the epitaxial growth technology of thin film single crystal, in particular to a graphite boat with a mother liquor cleaning device used for the growth of mercury cadmium telluride liquid phase epitaxial thin film material.

Background technique

At present, the graphite boat used in the push-boat type mercury cadmium telluride liquid phase epitaxy film material growth process is composed of a base, a bottom plate and a slider. A hole with the same size as the substrate is opened on the bottom plate for placing the substrate, and a hole is also opened on the slider for placing the mother liquid. By moving the slider or the bottom plate, the mother liquid is in contact with the substrate, and epitaxial growth is performed on the substrate. A layer of film material. Since the surface tension of tellurium is small, it is about 177dyn/cm at 500°C, so when growing horizontally, the mother liquor flows everywhere. After the growth is over, remove the slider, and it is difficult to push off the mother liquor by relying on the plane of the slider. As a result, the mother liquor is attached to the epitaxial layer, as shown in Figure 3. When the bonded mother liquid is cooled, due to the different thermal stress from the epitaxial film, a large number of dislocations will be generated around the mother liquid, which can expand 2-3mm from the edge of the mother liquid. If the size of the substrate is 20×20mm ² , the maximum amount of mother liquor to be adhered can reach 7×20mm ² , accounting for nearly one-third of the area. If the surrounding stress area is removed, the actual usable area is 10×20mm ^2. It is only half of the original substrate area, so the adhesion of the mother liquid greatly reduces the effective use area of the liquid phase epitaxial film. See MGAstles, N Shaw and G Blackmore Semicond Sci Technol Vol 8 (1993) S211; Yasumura K, Murakmi T, et al., J. Cryst. Growth, Vol 117, 1992, 20.

The object of the present invention is to provide a graphite boat with a mother liquor removal device, through which the mother liquor remaining on the surface of the epitaxial layer is removed, and the effective use area of the epitaxial film is increased.

The graphite boat with the mother liquid removal device of the present invention comprises: a bottom plate, a slide block and a base for fixing the bottom plate and the slide block, the bottom plate is placed on the base, and the slide block is placed on the top of the bottom plate. A hole with the same size as the epitaxial substrate is opened on the bottom plate, and a quartz spacer for adjusting the height of the substrate and the opening of the hole is built in the hole, and the substrate is placed on the quartz spacer. There is a channel for placing the mother liquid on the slider. The size of the channel is slightly smaller than the substrate. It is advisable to be 0.5mm away from the periphery of the substrate. There are two small rectangular grooves on the surface of the slider that is in contact with the bottom plate behind the channel. , the length direction of the small groove is perpendicular to the moving direction of the slider. The cross-sectional shape of the small groove is low at the front and high at the rear, which looks like a shovel. In order to make the small groove collect the residual mother liquor more thoroughly, the length of the small groove should be longer than the side length of the substrate 1-2mm. During the epitaxial growth of the film, the mother liquid is covered on the substrate by moving the slider or the base, and the film is grown. After the growth is completed, the small groove is collected by the movement of the slider to collect the epitaxial film remaining on the epitaxial film. mother liquor.

The greatest advantage of the present invention is that a small groove shaped like a shovel is added to the slider, and the mother liquor remaining on the epitaxial film can be effectively removed by the movement of the slider and the surface tension of the mother liquor after the growth of the epitaxial film is completed.

The device is mainly used for removing residual mother liquor in mercury cadmium telluride liquid phase epitaxy, and of course it can also be used for removing residual mother liquor in liquid phase epitaxy of other II-VI or III-V compound semiconductors.

Description of drawings

Fig. 1 is the schematic diagram of placing quartz gasket and substrate on the base plate of liquid phase epitaxial graphite boat;

Fig. 2 is the schematic diagram when the mother liquid on the slider in the liquid phase epitaxial graphite boat is moved on the substrate for epitaxial growth;

Fig. 3 is a schematic diagram of removing the mother liquid from the substrate after the end of the growth with residual mother liquid;

Fig. 4 is the schematic diagram that the present invention has two small grooves on the slider to scrape off the residual mother liquor on the substrate;

Fig. 5 is a plan view with two small grooves on the side where the slider contacts the bottom plate;

Fig. 6 is a schematic diagram of three gaps on the graphite base plate.

Detailed ways

As shown in Figure 4, the graphite boat that has mother liquor cleaning device of the present invention comprises: base plate 1, slide block 2 and the base 9 of fixing base plate and slide block, base plate is placed on the base, and slide block places above the base plate.

(1) slider

There is a hole 11 on the slider, which is used to place the mother liquid. The size of the hole is slightly smaller than the substrate, and it is better to be 0.5mm away from the periphery of the substrate. If the size of the substrate is 20×20mm ² , the size of the hole is 19× 19mm ² , so that the mother liquor will not flow down from the gap between the substrate and the bottom plate. Immediately behind the channel, there are two rectangular small grooves 8 on the side that is in contact with the bottom plate. The length direction of the small grooves and the movement of the slider The direction is perpendicular, and the length of the small groove is slightly longer than the substrate, that is, if the size of the substrate is 20×20mm ² , the length of the small groove is 22mm, the cross-sectional shape of the small groove is low at the front and high at the back, like a shovel, and the front edge The height is 1.5mm, the rear height is 2mm, and the width of the small groove is 4mm-6mm, as shown in Figure 4. The front is low and the rear is high like a small groove of a shovel. When the slider moves on the bottom plate, it removes the residual mother liquor like a bulldozer .

(2) Graphite bottom plate

The graphite base plate has a channel 10 for placing the quartz gasket and the substrate, as shown in Figure 6, the quartz gasket 4 is placed below, the substrate 5 is placed on the quartz gasket, and the quartz gasket is used as the adjustment substrate to leave the hole. For the crossing height, the following gaps should also be considered in the specific operation process, namely, the gap d between the bottom plate 1 and the base 9, the gap f between the quartz gasket 4 and the bottom plate 1, and the gap f between the quartz gasket 4 and the substrate 5. The gap e between them is less than 5um by measuring, and the unevenness between the quartz gasket and the substrate is also less than 5um, so considering the above factors, after the substrate is placed, the gap between the substrate and the slider should be 35um , 15um is the thickness of the epitaxial film layer 6, and the remaining 20um is the superposition of the above-mentioned gaps and unevenness. If there is no gap after the growth of the epitaxial layer 6, the surface will scratch the slider 2, and if the gap is too large after the growth, a lot of mother liquid will be left on the surface.

Since the thickness of the substrate 5 is difficult to precisely control during polishing, and generally fluctuates up and down by 10 um, it is necessary to select quartz gaskets 4 of different thicknesses to match it. The thickness difference of the quartz gasket is 20um, and through the control of the etching time before the substrate is loaded into the boat, generally, the gap between the substrate and the slider 2 can be basically controlled to be 35um.

If the bottom plate 1 is measured at the four corners with a thickness meter after the quartz gasket 4 is placed, the height of a+b as shown in Figure 1, and the height of Δ(a+b) is controlled to be less than 5um, put the substrate 5 Finally, the final 35um gap also has a maximum variation of 15um, so carefully adjust the various gaps to minimize the variation in the 35um gap, and the use of two small grooves 8 in the slider 2 can make the surface of the epitaxial layer 6 No scratches, no stains.

The implementation of the whole set of operations is to measure the thickness of the substrate 5 first, then select the matching quartz spacer 4, put it into the bottom plate 1, measure the height of a+b at the four corners, and control the height of Δ(a+b) within 5um , the thickness of the substrate 5 is controlled by an etchant to be b, and the height of the remaining a is the epitaxial layer 6 plus 20um. Scratching, the surface of the epitaxial film layer has neither residual mother liquid nor scratched the surface of the film layer.

The designer of the present invention has a Cd _0.96 Zn _0.04 Te substrate, a thickness of 890um, and a size of 20×20mm ² . After using this device, a Hg _0.77 Cd _0.23 Te liquid phase epitaxial layer with a surface as bright as a mirror and no dipping liquid is grown, with a thickness of It is 15um, and the infrared response wavelength is about 8um. On a Cd _0.96 Zn _0.04 Te substrate with a size of 20×30mm ² and a thickness of 900um, a Hg _0.774 Cd _0.226 Te liquid-phase epitaxial layer with a thickness of 15um and an infrared response was grown without liquid after using this device. The wavelength is about 10um. All of the above liquid phase epitaxy materials have successfully produced 256-element line arrays and 64×64-element area array infrared focal planes.

Claims (2)

1. graphite boat that has mother liquid remover that is used for phase epitaxial growth of Te-Cd-Hg film comprises: the base (9) of base plate (1), slide block (2) and fixed base plate and slide block, and base plate is placed on the base, and slide block is put on base plate;

A. have on the base plate and epitaxial substrate (5) duct of a size (10), the duct is built-in with the quartzy pad (4) of regulating substrate and opening of the channel height, places substrate (5) on the quartzy pad;

B. have the duct (11) of placing mother liquor (3) on the slide block, the size in duct is slightly less than substrate (5), is advisable with the peripheral 0.5mm that leaves substrate; It is characterized in that:

C. have two rectangular sulculuses (8) on the back of duct (11) and the contacted slide block of base plate (1) (2) face, the length direction of sulculus and the travel direction of slide block are perpendicular.

2. the graphite boat that has mother liquid remover that is used for phase epitaxial growth of Te-Cd-Hg film according to one kind of claim 1., it is characterized in that: the cross-sectional shape of said sulculus (8) is that low early and high after likeness in form one is scoop, the length of sulculus is slightly larger than substrate, is advisable to exceed substrate edge two 1mm.

Images