WO2018004147A1

WO2018004147A1 - Method for manufacturing phase change memory by using laser

Info

Publication number: WO2018004147A1
Application number: PCT/KR2017/005992
Authority: WO
Inventors: 박홍진; 최기철; 김민호
Original assignee: 주식회사 비에스피
Priority date: 2016-06-28
Filing date: 2017-06-09
Publication date: 2018-01-04
Also published as: KR101727960B1

Abstract

The present invention relates to a method for manufacturing a phase change memory including an electrode unit, which causes a phase change in a phase change material and is disposed at the lower side of the phase change material, and the phase change material, which has a resistance that changes while the phase change material is being phase-changed by the electrode unit, the method comprising a deposition step, a first emission step, and a second emission step. In the deposition step, the electrode unit is disposed at the lower side of a trench formed in a substrate and the phase change material is deposited on the substrate. In the first emission step a first laser beam having a first energy intensity higher than that of a melting point of the phase change material is emitted at the phase change material. In the second emission step, a second laser beam having a second energy intensity lower than the first energy intensity and lower than that of the melting point of the phase change material is emitted at the phase change material. The second laser beam emitted in the second emission step is emitted at a set time later than that of the first laser beam emitted in the first emission step, the phase change material is melted by the first emission step and introduced into the trench, and the temperature enabling the phase change material to flow into the trench is maintained by the second emission step.

Description

Phase change memory manufacturing method using laser

The present invention relates to a method for manufacturing a phase change memory using a laser, and more particularly, to a method for manufacturing a phase change memory using a laser for melting and filling a phase change material in a trench formed in a substrate by irradiating a laser beam on the phase change material.

Phase-change random access memory (PRAM) is a next-generation memory semiconductor that stores data by determining a phase change of a specific material. Phase change memory has both the advantages of flash memory, which does not erase stored information even when power is lost, and the advantages of DRAM, which has a high processing speed.

Phase change memory includes phase change materials exhibiting two or more different states, where the phase change materials have amorphous and crystalline states. In general, the crystalline state has an ordered lattice structure while the amorphous state has a more misaligned structure. Since the amorphous state and the crystalline state have different resistances and state transitions occur in response to temperature changes, they can be used to store data bits.

1 is a view for explaining a problem in manufacturing a phase change memory using a laser.

Referring to FIG. 1, the phase change memory includes a phase change material 10, an electrode part 20, and a switch element 30, and the phase change material 10, the electrode part 20, and a switch from an upper side to a lower side. The elements 30 are arranged in order.

The phase change material 10 is changed in phase by a power applied to the electrode part 20, and the resistance is changed. The electrode part 20 causes a phase change of the phase change material 10, and the phase change material 10 Is disposed on the lower side. The switch element 30 is disposed below the electrode portion 20.

Referring to the process of manufacturing the phase change memory, first, the phase change material 10 is deposited on the trench 2 formed on the substrate 1, and then the laser beam L is irradiated onto the phase change material 10 to obtain an image. The change material 10 is melted so that the phase change material 10 is evenly filled in the trench 2.

However, as shown in (a) of FIG. 1, when the aspect ratio of the trench 2 is recently increased, when the energy intensity of the irradiated laser beam L is insufficient, the deposited phase change material 10 is formed. There is a problem that the empty space 11 is formed inside the trench 2 without filling properly in the trench 2. The empty space 11 formed as described above finally causes a significant increase in the resistance of the phase change memory.

In addition, as shown in FIG. 1B, when the energy intensity of the irradiated laser beam L is excessive, a material having a low melting point is volatilized out of the material constituting the phase change material 10. The composition change of 10 occurs. As such, the material 12 having the composition change is difficult to perform the basic functions of the phase change memory as physical properties are changed.

In addition, when the energy intensity of the irradiated laser beam L is excessive, there is a problem that heat damage occurs in the switch element 30 due to heat, resulting in a failure of the phase change memory.

Therefore, the problem to be solved by the present invention is to solve such a conventional problem, by controlling the energy intensity of the laser beam irradiated to the phase change material to maintain a temperature condition suitable for melting the phase change material, Phase change using a laser that allows materials to be efficiently reflowed into the trench to prevent the formation of empty spaces and changes in the composition of the phase change material and to prevent thermal damage to the switch elements formed under the electrode. A memory manufacturing method is provided.

Phase change memory manufacturing method using a laser of the present invention to achieve the above object, the phase change of the phase change material and the electrode portion disposed under the phase change material, and the phase change by the electrode A method of manufacturing a phase change memory including a phase change material, the resistance of which is changed, wherein the electrode is disposed under a trench formed in a substrate, and the deposition step of depositing the phase change material on the substrate; A first irradiation step of irradiating the phase change material with a first laser beam having a first energy intensity higher than a melting point of the phase change material; And a second irradiation step of irradiating the phase change material with a second laser beam having a second energy intensity lower than the first energy intensity and lower than a melting point of the phase change material. The second laser beam may be followed by a predetermined time after the first laser beam irradiated in the first irradiation step, and the phase change material is melted and introduced into the trench by the first irradiation step, and the second irradiation step is performed. The temperature at which the phase change material is allowed to flow into the trench is maintained.

In the method of manufacturing a phase change memory using a laser according to the present invention, the preceding first laser beam and the following second laser beam may overlap a predetermined period.

In the method of manufacturing a phase change memory using a laser according to the present invention, the electrode part comprises titanium nitride (TiN), and the phase change material is chalcogenide-based germanium (Ge) -antimony (Sb) -teleul. It may include a ride (Te) metal alloy (GST).

In the method of manufacturing a phase change memory using a laser according to the present invention, the first laser beam includes a laser beam in an ultraviolet wavelength band having a relatively low absorption rate of the electrode portion among an ultraviolet wavelength band and a visible light wavelength band, and the second laser beam. May include a laser beam in a visible light wavelength band having a relatively high absorption rate of the phase change material among the ultraviolet light wavelength band and the visible light wavelength band.

In the method of manufacturing a phase change memory using a laser according to the present invention, the first laser beam and the second laser beam are formed in a rectangular shape and irradiated at the same position of the phase change material, and have a top hat shape. It may have an energy intensity distribution of.

According to the method of manufacturing a phase change memory using the laser of the present invention, it is possible to prevent generation of empty spaces in the trench and composition change of the phase change material, and to prevent thermal damage of the switch element formed under the electrode.

In addition, according to the method of manufacturing a phase change memory using the laser of the present invention, it is possible to block the thermal penetration to the switch element and to smoothly reflow the phase change material.

Further, according to the method of manufacturing a phase change memory using the laser of the present invention, the heat applied to the entire irradiated portion can be made uniform.

1 is a view for explaining a problem in manufacturing a phase change memory using a laser,

2 is a view schematically showing an example of laser equipment for implementing a method of manufacturing a phase change memory using a laser of the present invention;

3 is a diagram illustrating a method of manufacturing a phase change memory using a laser according to an embodiment of the present invention.

4 is a diagram illustrating energy intensities of a first laser beam and a second laser beam used in the method of manufacturing a phase change memory using the laser of FIG. 3.

FIG. 5 is a diagram illustrating absorption rates of a phase change material and an electrode part in the method of manufacturing a phase change memory using the laser of FIG. 3.

Hereinafter, embodiments of a method of manufacturing a phase change memory using a laser according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a view schematically showing an example of laser equipment for implementing a method of manufacturing a phase change memory using a laser of the present invention, and FIG. 3 is a method of manufacturing a phase change memory using a laser according to an embodiment of the present invention. 4 is a diagram illustrating energy intensities of a first laser beam and a second laser beam used in the method of manufacturing a phase change memory using the laser of FIG. 3, and FIG. 5 is a view of the image using the laser of FIG. 3. In the manufacturing method of the change memory, the absorption rate of the phase change material and the electrode portion is shown.

2 to 5, in the method of manufacturing a phase change memory using a laser according to the present embodiment, a phase change is formed in the trench 2 formed in the substrate 1 by irradiating the phase change material 10 with a laser beam. Melting and filling the material 10 includes a deposition step S10, a first irradiation step S20, and a second irradiation step S30.

First, referring to FIG. 2, a laser apparatus for implementing a method of manufacturing a phase change memory using a laser of the present invention will be described.

The laser device 100 for manufacturing a phase change memory includes a first laser output unit 110, a first power adjuster 111, a second laser output unit 120, a second power adjuster 121, and a delay generator. And a homogenizer 130.

As shown in FIG. 1, the phase change memory manufactured by the laser device 100 for manufacturing the phase change memory of the present embodiment includes a phase change material 10, an electrode unit 20, and a switch element 30. The phase change material 10, the electrode part 20, and the switch element 30 are disposed in an order from an upper side to a lower side. The phase change material 10 is changed in phase by a power applied to the electrode part 20, and the resistance is changed. The electrode part 20 causes a phase change of the phase change material 10, and the phase change material 10 Is disposed on the lower side. The switch element 30 is disposed below the electrode portion 20.

The first laser output unit 110 outputs the first laser beam L1 irradiated to the phase change material 10. The first laser beam L1 output from the first laser output unit 110 is preferably a laser beam in an ultraviolet wavelength band, and in particular, may be a laser beam having a wavelength of about 266 nm.

The first power adjusting unit 111 adjusts the energy intensity of the first laser beam L1 output from the first laser output unit 110. The first laser beam L1 whose energy intensity is adjusted by the first power adjusting unit 111 has a first energy intensity higher than the melting point of the phase change material 10.

The second laser output unit 120 outputs a second laser beam L2 irradiated to the phase change material 10. The second laser beam L2 output from the second laser output unit 120 is preferably a laser beam in the visible wavelength range, and may be a laser beam having a wavelength of about 532 nm.

The second power adjusting unit 121 adjusts the energy intensity of the second laser beam L2 output from the second laser output unit 120. The second laser beam L2 whose energy intensity is adjusted by the second power adjusting unit 121 is lower than the first energy intensity of the first laser beam L1 and lower than the melting point of the phase change material 10. You have strength.

The delay generator 122 trails the second laser beam L2 irradiated onto the phase change material 10 after the predetermined time from the first laser beam L1.

The first laser beam L1 and the second laser beam L2 are irradiated at the same position of the phase change material 10. The first laser beam L1 having a relatively high energy intensity is irradiated first, and is relatively The second laser beam L2 having a low energy intensity is irradiated by the delay generator 122 to be delayed by a predetermined time.

The first laser beam L1 whose energy intensity is adjusted by the first power adjusting unit 111 and the second laser beam L2 whose energy intensity is adjusted by the second power adjusting unit 121 are respectively reflected by a reflecting mirror. The reflection is input to the homogenizer 130.

The homogenizer 130 is formed such that the first laser beam L1 and the second laser beam L2 have an energy intensity distribution in the form of a top hat. In the homogenizer 130, the first laser beam L1 and the second laser beam L2 may overlap each other to be irradiated at the same position of the phase change material 10, and a cross section may be formed in a square shape.

When irradiating the first laser beam L1 and the second laser beam L2 to the phase change material 10, the homogenizer 130 first laser beam so that uniform heat is applied to the entire irradiated portion. The energy intensity of the L1 and the second laser beam L2 is molded to have an energy intensity distribution in the form of a top hat.

As described above, the first laser beam L1 and the second laser beam L2 finally formed by the homogenizer 130 have a phase change material 10 stacked on the substrate 1 with a difference in energy intensity and a time difference. ) And the phase change material 10 irradiated with the first laser beam L1 and the second laser beam L2 are melted and flow into the trench 2 formed in the substrate 1 to be filled.

3 to 5, a method of manufacturing a phase change memory using the laser of the present embodiment will be described using the laser device 100 for manufacturing the phase change memory described above.

In the deposition step S10, the phase change material 10 is deposited on the trench 2 formed on the substrate 1 and the upper surface of the substrate 1. An electrode portion 20 is disposed below the trench 2 formed in the substrate 1, and a switch element 30 is disposed below the electrode portion 20.

The phase change material 10 to be deposited is preferably a chalcogenide-based germanium (Ge) -antimony (Sb)-telluride (Te) metal alloy (GST), and is located below the phase change material 10. It is preferable that the electrode portion 20 to be arranged is titanium nitride (TiN), and the switch element 30 disposed below the electrode portion 20 is preferably a germanium (Ge) -selenium (Se) metal alloy.

The first irradiation step S20 irradiates the phase change material 10 deposited on the substrate 1 with the first laser beam L1 having a first energy intensity higher than the melting point of the phase change material 10.

The energy intensity of the first laser beam L1 output from the first laser output unit 110 is adjusted by the first power adjusting unit 111, so that the first laser beam L1 is a melting point of the phase change material 10. It will have a higher first energy intensity.

The second irradiation step S30 may include a phase change material in which a second laser beam L2 having a second energy intensity lower than the first energy intensity and lower than the melting point of the phase change material 10 is deposited on the substrate 1. Investigate in 10).

The energy intensity of the second laser beam L2 output from the second laser output unit 120 is adjusted by the second power adjusting unit 121 so that the second laser beam L2 is lower than the first energy intensity and has a phase change. It has a second energy intensity lower than the melting point of the material 10.

As shown in FIG. 4, in the present embodiment, the second laser beam L2 irradiated in the second irradiation step S30 is fixed for a predetermined time than the first laser beam L1 irradiated in the first irradiation step S20. The preceding first laser beam L1 and the following second laser beam L2 may overlap each other for a predetermined period. Using the delay generator 122 shown in FIG. 2, the second laser beam L2 irradiated to the phase change material 10 may be trailed after the predetermined time from the first laser beam L1.

When irradiating a laser beam to melt the phase change material 10 deposited on the substrate 1 and the trench 2 portion, the temperature of the surface of the phase change material 10 to which the laser beam is irradiated is about 630 degrees or more. It is desirable to maintain a very narrow temperature range of 700 degrees.

When the energy intensity of the irradiated laser beam is insufficient, a problem arises in that the phase change material 10 is not properly filled in the trench 2 and an empty space 11 is formed in the trench 2, and the irradiated laser When the energy intensity of the beam is excessive, the composition of the phase change material 10 may change due to volatilization of telluride Te having a low melting point among the materials constituting the phase change material 10 or heat damage to the switch element 30. This happens a problem occurs.

Therefore, in the present embodiment, the above-described problems can be solved by irradiating two laser beams having different energy intensities over time.

First, the phase change material 10 is irradiated with a first laser beam L1 having a first energy intensity higher than the melting point of the phase change material 10. The energy intensity of the first laser beam L1 is an energy intensity such that the temperature of the surface of the phase change material 10 is maintained at about 630 to 700 degrees, and the first laser beam irradiated in the first irradiation step S20. The phase change material 10 may be melted and introduced into the trench 2 by L1.

Subsequently, the second laser beam L2 is lower than the first energy intensity of the first laser beam L1 and has a second energy intensity lower than the melting point of the phase change material 10 and is delayed by the delay generator 122 for a predetermined time. Irradiate to the phase change material (10). The energy intensity of the second laser beam L2 is not an energy intensity enough to melt the phase change material 10, and the phase change material (2) is caused by the second laser beam L2 irradiated in the second irradiation step S30. The temperature at which 10) can flow into the trench 2 can be maintained.

When the first laser beam L1 is irradiated too short due to a change in the composition of the phase change material 10 or a heat damage of the switch element 30, the molten phase change material 10 is formed in the trench 2. There is a risk that the empty space 11 is formed inside the trench 2 because there is not enough time to flow into the trench 2.

Accordingly, by irradiating the phase change material 10 with the second laser beam L2 having a second energy intensity lower than the melting point of the phase change material 10, the composition change of the phase change material 10 or the switch element 30 is performed. In addition to preventing thermal damage, the molten phase change material 10 may be sufficiently secured to allow time to flow into the trench 2.

The first laser beam L1 and the second laser beam L2 having different energy intensities may be irradiated with a time difference while overlapping a predetermined portion of the pulse width, and the pair of pulses may be repeatedly changed by the phase change material 10. Is investigated.

On the other hand, it is preferable that the 1st laser beam L1 is a laser beam of an ultraviolet wavelength range, and it is preferable that the 2nd laser beam L2 is a laser beam of a visible wavelength range.

Referring to FIG. 5, the absorption rate 52 of the electrode unit is relatively low in the ultraviolet wavelength range, and relatively high in the visible wavelength range. Since the first laser beam L1 has a first energy intensity higher than the melting point of the phase change material 10, the energy of the first laser beam L1 is transmitted through the phase change material 10 and the electrode part 20. Penetration to the switch element 30 may cause thermal damage to the switch element 30. Accordingly, the first laser beam L1 is preferably a laser beam having a relatively low absorption rate 52 in the electrode portion, and may be a laser beam having a wavelength of about 266 nm.

The absorption rate 51 of the phase change material is relatively low in the ultraviolet wavelength range, and relatively high in the visible wavelength range. The second laser beam L2 has a second energy intensity lower than the melting point of the phase change material 10, and the second laser beam L2 is applied to the phase change material 10 that is already melted by the first laser beam L1. When the phase change material 10 is smoothly flowed into the trench 2 when irradiated), it is preferable to use a laser beam having a high absorption rate 51 of the phase change material as the second laser beam L2. desirable.

Accordingly, the second laser beam L2 is preferably a laser beam having a relatively high absorption wavelength 51 of the phase change material, and may be a laser beam having a wavelength of about 532 nm.

In addition, when irradiating the first laser beam (L1) and the second laser beam (L2) to the phase change material 10, the homogenizer 130 in the homogenizer 130 so that uniform heat is applied to the entire irradiated portion The energy intensity of the laser beam (L1) and the second laser beam (L2) is molded so as to have an energy intensity distribution in the form of a top hat, the cross section is formed in a square shape to the same position of the phase change material 10 Is investigated.

Phase change memory manufacturing method using a laser of the present invention configured as described above, by controlling the energy intensity of the laser beam irradiated to the phase change material by allowing the phase change material to be effectively reflowed into the trench, It is possible to prevent the occurrence of the empty space and the change of the composition of the phase change material in the trench, and to prevent the thermal damage of the switch element formed under the electrode portion.

In addition, the phase change memory manufacturing method using the laser of the present invention configured as described above, by selecting the wavelength band of the first laser beam and the second laser beam in consideration of the absorption rate of the electrode portion and the absorption rate of the phase change material, It is possible to block the thermal penetration of and to achieve an effect of smoothing the reflow of the phase change material.

In addition, the phase change memory manufacturing method using the laser of the present invention configured as described above, by forming a laser beam to have a top hat energy intensity distribution, thereby uniformly applying heat to the entire irradiated portion. The effect can be obtained.

The scope of the present invention is not limited to the above-described embodiments and modifications, but may be embodied in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the invention claimed in the claims, it is intended that any person skilled in the art to which the present invention pertains falls within the scope of the claims described in the present invention to various extents which can be modified.

The present invention is industrially applicable to the technical field of melting and filling a phase change material in a trench formed in a substrate by irradiating a laser beam to the phase change material.

Claims

A method of manufacturing a phase change memory including an electrode portion which causes a phase change of a phase change material and is disposed below the phase change material, and a phase change material whose resistance changes as the phase changes by the electrode part,

A deposition step of depositing the phase change material on the substrate, wherein the electrode part is disposed under the trench formed in the substrate;

A first irradiation step of irradiating the phase change material with a first laser beam having a first energy intensity higher than a melting point of the phase change material; And

And irradiating the phase change material with a second laser beam having a second energy intensity lower than the first energy intensity and lower than a melting point of the phase change material.

The second laser beam irradiated in the second irradiation step is followed by a predetermined time after the first laser beam irradiated in the first irradiation step,

The phase change material is melted and introduced into the trench by the first irradiation step, and the laser is characterized in that the temperature at which the phase change material flows into the trench is maintained by the second irradiation step. Phase change memory manufacturing method using.
The method of claim 1,

A method of manufacturing a phase change memory using a laser, characterized in that the preceding first laser beam and the following second laser beam overlap a predetermined period.
The method of claim 1,

The electrode portion includes titanium nitride (TiN),

The phase change material includes a chalcogenide-based germanium (Ge) -antimony (Sb) -telluride (Te) metal alloy (GST).
The method of claim 3,

The first laser beam includes a laser beam in the ultraviolet wavelength range of which the absorption rate of the electrode portion is relatively low among the ultraviolet wavelength band and visible light wavelength band,

And the second laser beam comprises a laser beam in a visible light wavelength band having a relatively high absorption rate of the phase change material among an ultraviolet wavelength band and a visible light wavelength band.
The method of claim 1,

The first laser beam and the second laser beam are formed in a rectangular shape and irradiated at the same position of the phase change material and have a top hat shape energy intensity distribution. Memory manufacturing method.