CN111270302B

CN111270302B - High-quality semiconductor silicon material consumable growth method

Info

Publication number: CN111270302B
Application number: CN201911362831.2A
Authority: CN
Inventors: 李辉; 秦英谡; 张熠; 穆童; 郑锴
Original assignee: Nanjing Crystal Growth & Energy Equipment Co ltd
Current assignee: Nanjing Jingsheng Equipment Co.,Ltd.
Priority date: 2019-12-26
Filing date: 2019-12-26
Publication date: 2021-01-15
Anticipated expiration: 2039-12-26
Also published as: CN111270302A

Abstract

The invention discloses a method for growing high-quality semiconductor silicon material consumables, which comprises the steps of material melting, crystal growth, isometric growth and cooling. The supercooling degree is manufactured under the crucible, so that the possibility that sediments on a thermal field piece above the crucible are scattered into the crucible is avoided, pollution is avoided, and the crystal quality is improved; in the whole crystal growth process, a reasonable solid-liquid growth interface is jointly created by descending the crucible and controlling the cooling proportion of the multi-section heater, impurities are favorably discharged during crystallization, the crystal quality is improved, the shape of the solid-liquid growth interface and the position of the solid-liquid growth interface relative to the heater are kept unchanged by adjusting the descending speed of the crucible, the cooling proportion of the multi-section heater and the cooling speed, the stability of the thermal field environment at the solid-liquid growth interface is ensured, the crystal growth is favorably realized, and the process control is convenient; the whole crystal growth cooling process adopts a power control mode, and is more direct and more accurate than the traditional temperature control mode.

Description

High-quality semiconductor silicon material consumable growth method

Technical Field

The invention belongs to the technical field of silicon crystal material growth.

Background

The silicon material has excellent performances such as unidirectional conductivity, heat-sensitive property, photoelectric property and doping property, and can grow into large-size high-purity crystals, so the silicon material becomes an important integrated circuit base material with wide global application.

The semiconductor silicon material is divided according to application scenes and can be divided into a single crystal silicon material for a chip and a silicon material for etching. The monocrystalline silicon material for the chip is a basic raw material for manufacturing a semiconductor device, forms a tiny circuit structure through a series of wafer manufacturing processes, and becomes the chip through links such as cutting, packaging, testing and the like, and is widely applied to the downstream market of integrated circuits. The etching silicon material is processed into a semiconductor grade silicon component and is used for etching a silicon electrode on equipment, the silicon electrode is gradually corroded and thinned in the processing process of silicon wafer oxide film etching and the like, and when the thickness of the silicon electrode is reduced to a certain degree, a new silicon electrode needs to be replaced, so that the silicon electrode is a core consumable material required in the wafer manufacturing and etching link. Impurities in silicon material consumables not only can reduce the service life of the material, but also can pollute a processed wafer, so the silicon material consumables require extremely low metal impurities and carbon-oxygen impurity content, the purity requirement of the silicon material consumables is far higher than that of the solar silicon crystals produced in batch at present, and brand new challenges are provided for the preparation process.

The prior technical scheme is that raw materials in a crucible are melted by adopting uniform heating, then a heating body or a heat shield is lifted, and the temperature is reduced by assisting in a temperature control mode, so that liquid silicon in the crucible is crystallized from bottom to top, and after the liquid silicon is completely crystallized, the crucible is cooled and opened. However, this solution also has drawbacks, including: 1. lifting the heating body or the heat shield can make the thermal field piece above the crucible move, and the sediment attached to the heating body or the heat shield can scatter into the crucible to cause pollution, so that the impurity content of the finished product is high; 2. the method is only a simple melting-recrystallization process, and the impurity content of the product is high; 3. the temperature is measured by adopting a fixed point, the temperature is reduced by a temperature control mode, the inaccuracy is realized, the solid-liquid interface is unreasonably controlled, and the crystal quality is poor.

Therefore, a new technical solution is needed to solve the above problems.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a method for growing high-quality semiconductor silicon material consumables, and aims to enable the operation to be simple, the automation degree to be high, the purity of the prepared silicon material to be higher and the gradient to be more reasonable.

The invention also provides a silicon material preparation method using the semiconductor silicon material consumable material growth furnace.

The technical scheme is as follows: in order to achieve the purpose, the invention can adopt the following technical scheme:

a method for growing high-quality semiconductor silicon material consumables comprises the following steps:

(1) and melting materials: placing 300-350kg of high-purity polysilicon raw material in a crucible, and controlling the power ratio of an upper section heater, a middle section heater and a lower section heater to be (1.6-2.2) under the vacuum condition: (1.7-2.4): (1-1.1) melting; after the raw materials are completely melted and the power is maintained for 1-2 hours, the power ratio of the upper, middle and lower section heaters is adjusted to be the growth ratio (2.9-3.2): (1.9-2.4): (0.8-1), the rotating speed of the crucible is 0.3-0.5 rpm; .

(2) Crystal growth: descending the crucible at the speed of 0.1-0.12 mm/h, forming a cold source below the crucible to cause supercooling, and starting crystallization of the melt in the central area at the bottom of the crucible; meanwhile, the upper, middle and lower section heaters are used according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) starting to reduce power; the rotating speed of the crucible is reduced to 0.1-0.2 rpm;

(3) and (3) isometric growth: when the crystal grows to the side wall of the crucible, entering an equal-diameter growth stage, and rotating the crucible at the speed of 0.1-0.2 rpm; the upper, middle and lower section heaters are arranged according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) continuously reducing power; the crucible is continuously descended, the descending speed of the crucible is 0.12-0.14 mm/h, and the position of the solid-liquid interface relative to the heater is kept unchanged;

(4) and (3) cooling: and (3) completely crystallizing the liquid silicon, cooling after the crystal growth is finished, and heating the upper, middle and lower section of heaters according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) starting to reduce the power, wherein the total speed is 8000-9000 w/h, when the total power is slowly reduced to a preset value, directly cutting off the power supply, and filling high-purity argon after 24-36 h, so that the whole crystal growth period is finished.

Further, in the step (1), the vacuum condition is 580 mbar.

Further, in the step (2), the total power reduction amplitude of the upper, middle and lower section heaters is 0.08-0.1 per mill of the total power.

Further, in the step (3), the total power reduction amplitude of the upper, middle and lower section heaters is 0.1-0.12 per mill of the total power.

Further, in step (4), the total power is slowly decreased to a predetermined value of 20 kw.

Furthermore, in the upper, middle and lower heaters, the upper heater is located above the crucible, the middle heater and the lower heater are arranged around the crucible, and the middle heater is located above the lower heater.

Has the advantages that: compared with the prior art, the technical scheme of the invention has the advantages that:

the supercooling degree is manufactured under the crucible, so that the possibility that sediments on a thermal field piece above the crucible are scattered into the crucible is avoided, pollution is avoided, and the crystal quality is improved; in the whole crystal growth process, a reasonable solid-liquid growth interface is jointly created by descending the crucible and controlling the cooling proportion of the multi-section heater, impurities are favorably discharged during crystallization, meanwhile, the thermal stress generated in the crystal growth process is reduced, the crystal quality is improved, the production period is shortened, the shape and the position of the solid-liquid growth interface relative to the heater are kept unchanged by adjusting the descending speed of the crucible, the cooling proportion of the multi-section heater and the cooling speed, the stability of the thermal field environment at the solid-liquid growth interface is ensured, the crystal growth is favorably realized, and the process control is convenient; the whole crystal growth cooling process adopts a power control mode, and is more direct and more accurate than the traditional temperature control mode.

Drawings

FIG. 1 is a schematic view of a growth furnace used in the present invention.

Detailed Description

The embodiment discloses a method for growing high-quality semiconductor silicon material consumables, which needs to provide an upper heater, a middle heater and a lower heater. The upper section heater is positioned above the crucible, the middle section heater and the lower section heater are arranged around the crucible, and the middle section heater is positioned above the lower section heater. Specifically, the growth furnace shown in fig. 1 may be used, and includes a side heat-insulating screen 1, an upper heat-insulating screen 2, a bottom heat-insulating screen 3, an upper heater 4, a middle heater 5, a lower heater 6, a crucible shaft 7, a graphite crucible 8, a quartz crucible 9, an upper electrode 10, a lower electrode 11, a middle electrode 12, a side furnace body 13, an upper furnace body 14, a lower furnace body 15, an overflow tray 16, a bottom heat-insulating plate 17, and a crucible cover 18. The upper heater 4 is positioned above the

crucibles

8, 9; the middle heater 5 and the lower heater 6 are disposed around the

crucibles

8, 9.

The growth method comprises the following steps:

(1) material melting: 300-350kg of high-purity polysilicon raw material is placed in a crucible, and the power ratio of an upper, a middle and a lower three-section heaters is controlled to be (1.6-2.2) under the vacuum condition (580 mbar): (1.7-2.4): (1-1.1) melting materials, wherein the power of an upper heater and a middle heater is higher than that of a lower heater, the physical characteristic that the density of solid silicon is smaller than that of liquid silicon is met, solid silicon always floats above the liquid silicon during melting, the upper middle part is hotter, the melting speed can be increased, the melting time is shortened, the possibility that carbon enters a melt in a graphite thermal field is reduced, and the quality of finished products is improved; after the raw materials are completely melted and the power is maintained for 1-2 hours, the power ratio of the upper, middle and lower section heaters is adjusted to be the growth ratio (2.9-3.2): (1.9-2.4): (0.8-1), and creating a thermal field environment suitable for crystal growth; the crucible rotation speed is 0.3-0.5 rpm.

(2) Crystal growth: simultaneously descending the bottom heat insulation plate and the crucible at the speed of 0.1-0.12 mm/h to open the distance between the bottom heat insulation plate and the bottom heat insulation screen to form a cold source, causing supercooling, starting crystallization of melt in the central area of the bottom of the crucible, descending the bottom heat insulation plate and the crucible, avoiding the possibility that sediment on a thermal field piece above the crucible is scattered into the crucible, and avoiding pollution; meanwhile, the upper, middle and lower three-section heaters are used according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) starting to reduce the power, wherein the total power reduction amplitude is 0.08-0.1 per mill of the total power, and the solid-liquid interface can be controlled more directly and more accurately than temperature control by adopting power control for cooling; the crucible rotation speed was reduced to 0.1-0.2rpm, reducing the disturbance in the melt.

(3) And (3) isometric growth: when the crystal grows to the side wall of the crucible, entering an equal-diameter growth stage, and rotating the crucible at the speed of 0.1-0.2 rpm; the diameter of the crystal is increased, latent heat of crystallization released during crystallization is increased, heat dissipation of the crystal needs to be improved, and the upper, middle and lower three-section heaters are arranged according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) continuing to reduce the power, wherein the total power reduction amplitude is 0.1-0.12 per mill of the total power; the descending speed of the bottom heat insulation plate and the crucible is 0.12-0.14 mm/h, the position of a solid-liquid interface relative to the heater is kept unchanged, the power cooling control is facilitated, and meanwhile the thermal field environment at the growth interface is kept unchanged; under the combined action of supercooling formed by a thermal field and cooling of a heating body, a solid-liquid interface forms a state that a lower solid protrudes to an upper liquid, the protruding angle is 135 degrees (the reasonable range is 120-150 degrees, the angle is smaller than 120 degrees, the crystal stress is overlarge, the processing is cracked, the angle is larger than 150 degrees, impurity removal is not favorable, impurities are easily concentrated in the center of the solid-liquid interface), and impurity removal during crystallization is facilitated.

(4) And (3) cooling: the liquid silicon is completely crystallized, the crystal is cooled after the growth is finished, and as the shape and the position of a solid-liquid interface are accurately controlled during the equal-diameter growth, the crystal almost has no residual stress, does not need a special annealing process and can be directly cooled; the upper, middle and lower three-section heaters are arranged according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) starting to reduce the power, wherein the total speed is 8000-9000 w/h, when the total power is slowly reduced to 20kw, directly cutting off the power supply, and filling high-purity argon after 24-36 h, and ending the whole crystal growth period.

The invention embodies a number of methods and approaches to this solution and the foregoing is only a preferred embodiment of the invention. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. A method for growing high-quality semiconductor silicon material consumables is characterized by comprising the following steps:

(1) and melting materials: placing 300-350kg of high-purity polysilicon raw material in a crucible, and controlling the power ratio of an upper section heater, a middle section heater and a lower section heater to be (1.6-2.2) under the vacuum condition: (1.7-2.4): (1-1.1) melting; the density of the solid silicon is less than that of the liquid silicon, the solid silicon always floats above the liquid silicon during melting, the upper middle part is hotter, the melting speed can be accelerated, the melting time is reduced, carbon in a graphite thermal field is reduced from entering a melt, and the quality of a finished product is improved; after the raw materials are completely melted and the power is maintained for 1-2 hours, the power ratio of the upper, middle and lower section heaters is adjusted to be the growth ratio (2.9-3.2): (1.9-2.4): (0.8-1), the rotating speed of the crucible is 0.3-0.5 rpm;

(2) crystal growth: simultaneously descending the bottom heat insulation plate and the crucible at the speed of 0.1-0.12 mm/h to open the distance between the bottom heat insulation plate and the bottom heat insulation screen to form a cold source, causing supercooling, and starting to crystallize melt in the central area of the bottom of the crucible to descend the bottom heat insulation plate and the crucible, so that the sediment on a thermal field piece above the crucible is prevented from scattering into the crucible, and pollution is avoided; meanwhile, the upper, middle and lower section heaters are used according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) starting to reduce power; the rotating speed of the crucible is reduced to 0.1-0.2 rpm;

(3) and (3) isometric growth: when the crystal grows to the side wall of the crucible, entering an equal-diameter growth stage, and rotating the crucible at the speed of 0.1-0.2 rpm; the upper, middle and lower section heaters are arranged according to the growth power ratio (2.9-3.2): (1.9-2.4): (0.8-1) continuously reducing power; the crucible is continuously descended, the descending speed of the crucible is 0.12-0.14 mm/h, and the position of the solid-liquid interface relative to the heater is kept unchanged; meanwhile, the thermal field environment at the growth interface is maintained to be unchanged; under the combined action of supercooling formed by a thermal field and cooling of a heating body, a solid-liquid interface forms a state that a solid below is protruded to liquid above, the protrusion angle is 135 degrees, and impurities are conveniently discharged during crystallization;

2. The method of claim 1, wherein: in step (1), the vacuum condition is 580 mbar.

3. The method of claim 2, wherein: in the step (2), the total power reduction amplitude of the upper, middle and lower section heaters is 0.08-0.1 per mill of the total power.

4. The method according to claim 3, wherein: in the step (3), the total power reduction amplitude of the upper, middle and lower section heaters is 0.1-0.12 per mill of the total power.

5. The method of claim 1, wherein: in step (4), the total power is slowly reduced to a predetermined value of 20 kw.

6. The method of claim 1, wherein: in the upper, middle and lower section heaters, the upper section heater is positioned above the crucible, the middle section heater and the lower section heater are arranged around the crucible, and the middle section heater is positioned above the lower section heater.