RU1827696C - Method for separating semiconductor plates into crystals - Google Patents

Abstract

The invention relates to the production of electronic equipment and can be used in the technology of manufacturing integrated circuits. SUMMARY OF THE INVENTION: a plate is scribed and thermal and mechanical effects are applied to it simultaneously, moreover, the thermal effect is carried out by creating a temperature gradient. For silicon wafers, the temperature field gradient is selected in the range from 180 deg / mm to 240 deg / mm, and the mechanical load in the range from 6 to 8 g / cm2. 1 s.p. f-ly, 3 ill.

Description

ate

WITH

The invention relates to the production of electronic computing equipment and can be used in the technology of manufacturing integrated circuits for memory devices.

The aim of the invention is to increase the yield of suitable crystals.

The goal is achieved. that the plate is simultaneously subjected to thermal effects, and the plate is taken by a cooled plate, the thermal effect being carried out by creating a temperature field gradient, wherein the stress vector of the uniform mechanical field and the temperature field gradient are parallel. For silicon wafers, the temperature field gradient is selected in the range from 180 deg / mm to 240 deg / mm, and the uniform mechanical field in the range from 6 to 8 g / cm2.

At present, the most widely used dividing of plates into crystals is scribing, which includes two stages.

Drawing on the surface of the plate parallel marks - notches with a certain step. In this case, a zone of plastically deformed silicon is created in the region of the grooves, containing microcracks, microcracks and distinguishing with increased local mechanical stresses. The width of the deformed zone reaches 270 microns and, after separation, decreases to 90 microns. Therefore, the elements of the LSI GC are located no closer than 100 microns from the edge of the crystal.

Fracture of the plate on the detached crystals is carried out by external mechanical stresses. All types of fault are varieties of basics00

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xl Os Yu Oh

3 18276964

1 xx method consisting in cantilever of FIG. Figure 3 shows a schematic diagram of the bending, bending of a cylindrical or spherical arrangement of external mechanical vectors (plane x. For the separation of the binary voltage a and thermomechanical crystals from the plate of the required voltage a, also shown

we bending tensile forces from I, 5 direction of the temperature gradient

 apol where. As can be seen from FIG. At a point 8 where is the length of the side of the crystal, and is the width of the temperature field, it is directed parallel to the external mechanical

In FIG. 1-3, a device is pre-installed, voltage m ut. and dividing the plate that implements the proposed method of stripping thermomechanical stresses 10 and directing the plates to crystals; in FIG. 1 are parallel to the surface of the scribing device for scribing the plate; the bathroom part of the surface S of the plate 2. FIG. 2 - a device for separating pla - since the surface S is under the action on crystals; in FIG. 3 - we present one-sided heating of the plate 2; the layout of the vectors of the external mea- sure expands, then the internal stresses of the chemical stress 7e and the internal ones act in the direction of deformation, i.e., thermomechanical stresses, in the direction of expansion of the plate.

The device (FIG. 1) contains a table - os - From this it can be seen that the external is uniform

1 d / ni of the placement of the plate 2, the mechanical field ae acts perpendicularly with the help of vacuum suction cups 3 the plate has a circular surface (since the machine moves to the table 1 and with the help of the Zlaz forces creates a plate 7 with its weight P),

cutter A moved by the device 5, and thermomechanical stresses pose risks - straight lines parallel to D of the horizontal plane S, which

crystallographic planes. Says thermal expansion Aly

the purpose of endowing the conditions of large disruption and therefore the plate joints under the action of a scriber

table - base 1 is cooled by flow-through axexDT, Oy auUuAT, water.

The device (Fig. 2) contains a table - os-where Cx and a thermal coefficients

Innovation 6, heated with hot water, on the expansion plate of the plate material, in the direction of which there is a notched surface X and Y

plate 2. fixed with in-Ex and Eu - Young's modules in the directions

by the power of vacuum suction cups 3. Top X and Y

the plate is loaded with plate 7, cooled to the temperature difference between cold water and. creating a field with bellows-35 and cool surfaces of plat.

voltages. gtin1

The proposed method for dividing the thermomechanical thermo-meshes and crystals into crystals consists in applying stresses in the X and Y directions.

coordinate table (Fig. 1) is cooled until identical conditions are reproduced

temperature, 5-20 C, then it is distributed on it 11 | inside the crystal e. invariance

lay plate 2 and using vacuum ur j the difference

suction cup 3 fix its position at a hundred-temperature Tg - Ti - AT provides

le 1. The plate is scribed in the given on.

board, after which the plates reproducing the same result are identical placed on another table (Fig. 2) 645 physical properties of materials with a scratched surface of onized plates and stability

n n technological scribing modes.

Table 6 is heated by passing. Constant load P prevents

hot water. The occurrence of bending deformation is placed on top of the plate by a cooling plate 7, As a result of creating -50 Here a field of uniform temperature difference of 50-65 ° С is created under the compression constraint, which determines

entom 200 deg / m. At the same time, the direction of propagation is the effect of a temperature gradient in microcracks. The value of the load P

l i.e., internal thermomechanical ones are selected experimentally for data and perpendicular to them55 diamond scriber. since it depends on the depth of the directional uniform mechanically-НЫ 3WQ3a plates and the width

th plate loading (external, eg, scribing of the track).

n) is sufficient to separate the plate; the lower temperature is heated to Ti

individual crystals. The plate is in direct thermal contact with the scribed surface of the crystal. In this case, the layers of the scribed surface of the plate are in the region of a higher temperature Ti and the layers of the lower - scribed part of the plate are uniformly expanded relative to the layers of its upper, cooled part. In this case, the risks of the scribed region containing the mouth of cracks 8 develop, that is, they expand and the mouth of cracks 8 rush inward to the cooled part of the plate, causing it to break along the scribing patterns under the action of internal forces. Under action, the scribed sections 8 are destroyed &; due to thermal stretching. With a constant gradient, constant tensile thermomechanical stresses are created in the plate, causing the natural propagation of microcracks in the directions of the accumulation of dislocations created by the diamond scraper.

The defects in the crystal structure along the scribing line are local in nature, there is a deformation field around them, where during the directional thermal activation, dislocations and slip lines change and further stress relaxation due to local damage occurs. Thermomechanical stresses arising due to the temperature gradient are quite large. To destroy the plate, it is necessary that where o is the tensile strength .. The value of o depends on the degree of deformation of the plate by the diamond scriber and the concentration of defects in the area of the marks and is removed up to 5 MPa. Polaga L 4.2 to and E 185 GPa, we find

ABOUT

5-10 (

4.2 185 10U

62 ° C.

For silicon, high temperature gradients are greater than 200 ° C / cm. In our experiments, the gradient of the temperature field is about 1800 ° C / cm at a temperature of 50-65 ° C. The destruction of the plates into individual crystals occurs within 10 - 12 s.

A feature of the proposed method of dividing plates into crystals consists in flexible stretching under the influence of internal thermomechanical tensile stresses. A flat along the entire cross-section surface of the chip of the chip along the scribed part is created upon fracture, and the plates are crystallized only under the influence of uniform tension by internal stresses.

The advantages of the proposed method of dividing plates into crystals are as follows: thermomechanical stresses create uniform thermomechanical tensile stresses along the plane of the plate due to the temperature gradient; uneven loading along the fault cross section, i.e., along the height of the plate, the forces acting in the cross section are not the same - lower (heated) more and lower (cold) less and therefore the nature of their action is reduced to separation by stretching adjacent crystals; the contact area of adjacent crystals in the wafer during the separation of the wafer into crystals continuously decreases and the tensile forces of the crystals are concentrated on the unbroken contact surface. By combining the gradients of the temperature field, i.e., directed thermo-mechanical stresses and uniform mechanical load (providing a drain of dislocations), directed destruction deep into the incisions of the plates created by the scribes is achieved. The proposed method of dividing the plates into crystals provides the expansion of the upper layer of the plate relative to

its lower layers and the simultaneous action of a uniform mechanical field, which causes the spread of destruction into the plate along the span plane.

Claims (2)

1. A method of dividing semiconductor wafers into crystals, including making cuts on the wafer surface, followed by heating it, heating and so that, in order to increase the yield, heating is carried out by pressing the wafer by pressing a heated plate. 2. The method according to claim 1, with the exception that for silicon wafers, the wafer is heated to a temperature at which the temperature gradient in the gap between the lower surface of the wafer and the wafer is 180 - 240 deg / mm, and the clamp Implemented with a force of 6-8 g / cm. Z / Ј I l "". S & .. ftz.Z  7to rov // flV - M ftpo / repaired yor cha foda