EP3303141A1

EP3303141A1 - Packaging of polysilicon

Info

Publication number: EP3303141A1
Application number: EP16725815.1A
Authority: EP
Inventors: Werner Lazarus; Franz Bergmann; Matthias Vietz
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2015-05-26
Filing date: 2016-05-20
Publication date: 2018-04-11
Also published as: DE102015209629A1; JP2018521908A; TWI619646B; KR20170130595A; JP6567689B2; US20180148198A1; US10689135B2; KR102055207B1; TW201641370A; MY191009A; CN107454884A; WO2016188893A1; CN107454884B

Abstract

The invention relates to a method for packaging polysilicon, comprising: providing polysilicon in the form of chunks of broken polysilicon rods, which were produced by depositing polysilicon in the form of rods in a reactor; cleaning the polysilicon; packaging the polysilicon; wherein the polysilicon is in a process shell during the cleaning and wherein the polysilicon is packaged into a plastic bag from the process shell in that the process shell and the plastic bag are fastened to a filling unit, which is set into rotation such that the polysilicon slides from the process shell into the plastic bag.

Description

PACKAGING POLYSILICIUM

The invention relates to the packaging of polysilicon. Polycrystalline silicon or polysilicon in short can be deposited by means of the Siemens method of chlorosilanes in rod form. Subsequently, the

rod-shaped polysilicon usually broken as free of contamination to fragments or broken polysilicon. Such a method as well as a

corresponding crushers are described in EP 1 645 333 A1.

Polysilicon breakage is a sharp-edged, non-free-flowing bulk material.

When crushing the high-purity silicon but contaminated with foreign atoms. These are in particular metal carbide or diamond residues as well as metallic impurities.

Therefore, silicon breakage is exploited for higher value applications, e.g. for the

Single crystal pulling before further processing and / or packaging usually cleaned. This usually happens in one or more chemical

Wet cleaning steps.

In this case, mixtures of different chemicals and / or acids are used, in particular to remove adhering foreign atoms from the surface again.

EP 0 905 796 B1 claims a process for producing silicon which has a low metal concentration, characterized in that the silicon is washed in a preliminary purification in at least one stage with an oxidizing cleaning solution which comprises the compounds hydrofluoric acid (HF),

Hydrochloric acid (HCl) and hydrogen peroxide (H2O2) and is washed in a main cleaning in a further stage with a cleaning solution containing nitric acid (HNO3) and hydrofluoric acid (HF), and Hydrophilization is washed in a further step with an oxidizing cleaning solution.

After the cleaning step, the purified polysilicon fraction is usually packed in plastic bags.

From US 7013620 B2 a device for fully automatic transporting, weighing, portioning, filling and packaging of a high-purity polysilicon fracture is known. The device comprises a polysilicon breakthrough chute, a polysilicon chute weighing device connected to a hopper, silicon baffles, a filling device which forms a plastic bag from a high purity plastic film (e.g., PE), and a

Welding device for the polysilicon-filled plastic bag. By the reinforcement of built-in parts of the device with silicon or with a

highly wear-resistant plastic to a low-contamination packaging of Polysiliciumbruchs be enabled.

US 2010/0154357 A1 discloses a device for packaging of

Polysilicon fracture, consisting of a Rundläufer-, filling and closing machine or a non-circular device arranged with a filling station and a closure station in which a PE bag is suspended on a gripper system is moved from station to station in a clock sequence, characterized in that the filling station comprises a freely suspended energy absorber made of a nonmetallic low-contamination material which is introduced into the PE bag before filling the PE bag with polycrystalline silicon and, after filling the PE bag with polycrystalline silicon, is removed from the PE bag and the filled PE bag is conveyed by means of the gripper system in the closure station and is closed there. According to US 2010/0154357 A1, the polysilicon is first weighed, in a

Portioned and cleaned process shell before he in these portioned units via a filling device with freely hanging flexible hose from a

nonmetallic low-contamination material in a freely suspended introduced high purity plastic bag and then the plastic bag is sealed. At the filling station of the device, the bag is opened. About a conveyor, which is covered with silicon or a low-contamination material and with a movable flexible hose from a

non-metallic material, eg. As plastic, is connected by this

Tube filled the sharp-edged polysilicon break in the opened PE bag. The conveyor is, for example, a conveyor trough or a chute, preferably a chute. US 2012/0198793 A1 discloses a method for dosing and packaging polysilicon fragments, wherein a product stream of polysilicon fragments transported via a conveyor, separated by means of at least one sieve into coarse and fine fragments, weighed by means of a metering balance and metered to a target weight, via a discharge chute is discharged and transported to a packaging unit, where the polysilicon fragments are filled into a first plastic bag and this is sealed, this plastic bag containing polysilicon fragments is packed in another molded by a former plastic bag, which is then welded, said at least one screen and the metering scale on their surfaces at least partially comprise a hard metal and the former for forming the plastic bag has a wear-resistant coating.

US 2013/0042582 A1 discloses a method for packaging polycrystalline silicon, in which polycrystalline silicon is filled by means of a filling device into a plastic bag, characterized in that a storage container has an opening through which silicon is filled, wherein the plastic bag after filling the Reservoir is pulled with silicon over the reservoir and the reservoir is then rotated so that the silicon from the reservoir into the plastic bag slips.

It has been found that during the packaging of fragments of a certain size class, for. B, for fraction sizes from 20 to 60 mm, too undesirable smaller silicon particles or fragments are formed. The proportion of such unwanted particles is 17000-23000 ppmw for such fraction sizes.

Hereinafter, all fragments or particles of silicon having such a size as to be cut off by a mesh screen with 8 mm x 8 mm square mesh will be referred to as fines. The fines are undesirable for the customer as they have a negative impact on customer processes. If the fines from the customer e.g. has to be separated by sieving, this means an increased effort.

In addition to the automatic packaging of polycrystalline silicon as in US 7013620 B2 is also a manual packaging of polycrystalline silicon in plastic bag in question. US 2012/098793 A1 reports that labor intensive manual packaging of purified polysilicon debris in a class 100 clean room is required to achieve the required high level of spot accuracy of less than +/- 1% for polysilicon breakage for the semiconductor industry. In this case, purified polysilicon fragments, which no longer have any metallic impurities on their surface, with high-purity gloves, z. As high-purity textile, PU or PE gloves, from a process bowl in which the cleaning is done, taken and placed in a PE double bag.

US 2014/0130455 A1 discloses a method for packaging polycrystalline silicon which is in the form of fragments comprising the following steps

- Providing polycrystalline silicon in a dosing system;

- filling polycrystalline silicon from the dosing system, through which

Fines are separated by sieves, in one below the dosing system

arranged plastic bags;

during filling, determining the weight of the plastic bag with the filled polycrystalline silicon and terminating the filling operation after reaching a target weight;

wherein during the entire filling process, a drop height of the polycrystalline Siliciums of dosing in plastic bag by means of at least one clamping device is kept less than 450 mm.

The drop height of the polycrystalline silicon from a conveyor trough of the metering system into the plastic bag should be less than 450 mm, preferably a maximum of 300 mm. This reduces the fines content.

By manual packaging, the fine fraction can be reduced even more clearly, for the crack size 20-60 mm from 17000 ppmw to 1400 ppmw.

However, manual packaging means a high expenditure and increased personnel costs.

In addition, it would be desirable to reduce the fines even further than feasible by manual packaging.

Therefore, the object of the invention was to automatically pack polycrystalline silicon and reduce the resulting fines to an extremely low level. The task was also to provide a device suitable for this purpose.

From the problem described, the problem of the invention resulted.

The object of the invention is achieved by a method for packaging polysilicon comprising providing polysilicon in the form of fragments of comminuted polysilicon rods produced by depositing polysilicon in rod form in a reactor, purifying the polysilicon, packaging the polysilicon, wherein the polysilicon during cleaning in one

Process bowl is located and wherein the polysilicon from the process bowl is packaged in a plastic bag, that process bowl and plastic bag are attached to a filling unit, which is set in rotation, so that the

Polysilicon from the process bowl slides into the plastic bag. The plastic bag is preferably a prefabricated

Double bag. Unlike in the prior art, the polysilicon is thus not packed in a first plastic bag, which then in a second

Plastic bag is inserted. The polysilicon is preferably filled directly into a double bag.

The double bag is attached to the packaging system, preferably clamped. In one embodiment, the plastic bag is in a former

prefabricated and then positively with the help of the former in the

Packing system introduced. In the simplest case, the former is a socket in which the molded plastic bag is located. Of the

Former is mechanically clamped to the packaging system. Of the

Shaper ensures that the plastic bag retains its shape during the rotational movement of the system.

It is ensured that no polysilicon fragment can fall out of the packaging installation during the filling process.

The polysilicon to be cleaned and packaged is initially in a process bowl. The polysilicon is purified in the process dish as described in US 2010/0154357 A1. The purification of the polysilicon in the

Process bowl can be carried out, for example, as described in EP 0 905 796 B1.

Notwithstanding the prior art, the filling of the plastic bag with polysilicon does not take place via a conveyor such as a conveyor trough or a chute, but directly from the process bowl. This has the advantage that the polysilicon in the process shell does not have to overcome a direct drop height. In addition, the process bowl is emptied into the bag or double bag via a rotary movement of process bowl and bag / double bag.

Due to the rotational movement of the process bowl and double bag, the polysilicon is placed in a roll / slip state and thus slides into the

opened double bag.

This results in the lowest possible fines.

In one embodiment, each empty process bowl is checked for its absolute emptying with weighing and / or camera system and released.

The packaging system comprises at least one filling unit. In the simplest case, this is a kind of funnel. Via the filling unit, the polysilicon slides from the process bowl into the

Plastic bag.

In one embodiment, the filling unit is made of silicon.

However, other low-silicon materials can be used.

A process bowl containing polysilicon is attached to the one opening of the filling unit. On the opposite side of the filling unit, a former with a PE double bag located therein is clamped or jammed.

In one embodiment, the process bowl consists of a chemical

resistant material.

It is advantageous if the former consists of a dimensionally stable material The bag and process tray can be loaded manually or automatically depending on throughput requirements.

In one embodiment, the packaging system comprises a base frame and a rotatable frame.

On the rotatable frame, the filling unit is attached. It drives a drive shaft, which sets the rotatable frame in rotation. Meanwhile, the emptying of the process bowl and thus the filling of the bag takes place. Depending on the size of the break, the rotational movement can be adjusted depending on the tilt angle.

The tilt angle in the context of the invention is the angle from which the polysilicon starts to slide out of the process bowl via the filling unit into the bag.

In one embodiment, as soon as the tilt angle is reached, the

Reduced rotational speed so that the entire filling of the bag takes place in the form of a sliding movement of the polysilicon. This ensures a particularly gentle packaging.

The system can be executed with one or more filling units. in one embodiment, there are up to ten rotatable fillers and the same number of process cups and plastic bags.

In one embodiment, the plant 2 comprises filling units.

Compared to the task of the process bowls is preferably the removal of the filled bags and at the same time plugging and clamping the new empty bag.

The processes of Beutelaufsteckens and bag removal can be automated. In one embodiment, a former receptacle is provided which serves to secure a former with a plastic bag.

In one embodiment, the plastic bag is slipped with its opening over one end of the filling unit. At the other end of the filling unit, the process bowl is fixed with the polysilicon to be packaged.

The base frame of the system in one embodiment includes feet and side mounting brackets.

Feet and Shaper recording can each be provided with a cover.

These covers and the lateral mounting brackets can be made of polysilicon low-contamination material. Preferably, they include liners of plastics (e.g., PU) or silicon.

In one embodiment, the rotating movement of the system is accomplished by a lift motor which drives a drive shaft and with a

Toothed belt drive is connected to toothed belt pulleys.

With respect to the above-mentioned embodiments of the

features of the invention can be realized either separately or in combination as embodiments of the invention.

Furthermore, they can describe advantageous embodiments that are independently protectable.

BRIEF DESCRIPTION OF THE FIGURE FIG. 1 shows schematically different time states of the packaging installation according to the invention.

List of reference numbers used 1 process bowl

2 filling unit

3 plastic bags

4 shapers

In Figure 1, the time course of the packaging process is shown.

Shown are process bowl 1, in which in the initial state t1 the

Polysilicon is, the filling unit 2, where the process bowl 1 and the

Plastic bag 3 are attached.

About the filling unit 2, the polysilicon of process bowl 1 in the

Plastic bag 3 introduced.

The plastic bag 3 is located in the former 4.

The former 4 serves as a shaped body for the plastic bag 3.

On the other hand, the former 4 is clamped to the filling unit 2 or to a receptacle intended for this purpose for the former, thus also ensures the fixation of the plastic bag.

In the figure, the axis of rotation is located.

At time t2, the polysilicon begins to slip or slide from the former 4 via the filling unit 2 into the plastic bag 3.

At this time, the rotational speed of the equipment should be reduced to ensure a sliding movement of the polysilicon during the entire filling process (e.g., time t3).

At time t4, the entire polysilicon is in the plastic bag 3. The rotation of the system can then be terminated. The filled plastic bag 3 is removed and, for example, welded, packed in a box and shipped.

Comparative example

For cleaning, the polysilicon is inserted into the process bowl.

The loaded weight in the process bowls is e.g. 5 kg plus a small surcharge for the etching removal, which depends on the size of the fragments.

After passing through the cleaning process, the target weight is in the

Process bowl 5 kg + - 50 g.

The process trays are then transported to the packaging.

There they are picked up by a robot by means of a gripping system and emptied onto a packaging chute.

At the end of the packaging chute is a double bag in a former

attached.

The double bag is filled by placing the chute with the polysilicon and allowing the polysilicon to slip into the bags. By emptying the process bowls onto the chute and sliding towards the bag, the polysilicon is reground. Thus, fines are generated.

Example The process trays are at the filling unit of an inventive

Clamping packaging system. At the other end of the filling unit, a double bag is attached in a former.

The double bag is filled by rotating the process tray and the double bag in a rotary motion, causing the polysilicon to slide into the bag.

The resulting fines decreased by more than 50% compared to the

Slide packing (comparative example). The above description of exemplary embodiments is to be understood by way of example. The disclosure thus made makes it possible for the skilled person, on the one hand, to understand the present invention and the associated advantages, and on the other hand, in the understanding of the person skilled in the art, also includes obvious ones

Modifications and Modifications of the Structures and Methods Described. It is therefore intended that all such alterations and modifications as well as equivalents be covered by the scope of the claims.

Claims

claims

1 . A process for packaging polysilicon comprising providing

Polysilicon in the form of fragments of shredded polysilicon rods produced by depositing polysilicon in rod form in a reactor, polysilicon purification, polysilicon packaging, wherein the

Polysilicon is located in a process bowl during cleaning, and wherein the polysilicon from the process bowl is packaged in a plastic bag by attaching process bowl and plastic bag to a filling unit that is rotated so that the polysilicon slides from the process bowl into the plastic bag.

2. The method of claim 1, wherein the plastic bag is located in a former, wherein the former is attached to the filling unit.

3. The method of claim 1 or claim 2, wherein the filling unit is made of silicon.

4. The method according to any one of claims 1 to 3, wherein each empty process bowl is controlled by means of a weighing and / or camera system for absolute emptying.

5. The method according to any one of claims 1 to 4, wherein from the time from which the polysilicon begins to slide out of the process bowl via the filling unit in the bag, the rotational speed is reduced.

6. The method according to any one of claims 1 to 5, wherein it is the plastic bag is a prefabricated double bag.