Apparatus and method for depositing a layer of semiconductor material on a substrate wafer

Abstract

The invention relates to an apparatus for depositing a layer of semiconductor material on a substrate wafer, said apparatus comprising: a base ring between an upper and a lower dome; a susceptor acting as a support for the substrate wafer during deposition of the layer; a gas inlet and a gas outlet; an exhaust gas line and gas supply lines for conducting process gas over an upper lateral surface of the substrate wafer; a slit valve tunnel and a slit valve door; and a lifting and rotating means for lifting and rotating the susceptor and the substrate wafer, characterised in that one or more components of the apparatus which consist of stainless steel are covered by an amorphous layer containing silicon and hydrogen.

Description

[0001] Apparatus and method for depositing a layer of semiconductor material on a substrate wafer

[0002] The invention relates to a device for depositing a layer of semiconductor material on a substrate wafer by means of vapor deposition. The invention also relates to a method in which the device is used.

[0003] State of the art / problems

[0004] Sophisticated applications in the field of manufacturing base material for the electronics industry include the deposition of a layer of semiconductor material on a substrate wafer, in particular the deposition of an epitaxial layer on the substrate wafer.

[0005] During the deposition of the layer, the substrate wafer rests on a susceptor at deposition temperature. Process gas is passed over the upper side surface of the substrate wafer, causing fission products of a chemical compound (precursor) contained therein to crystallize as a material layer on the side surface.

[0006] Devices such as the single-wafer reactor described in US 2009 314205 A1 are particularly suitable for this purpose. It has a base ring arranged between an upper and a lower dome. Together, they form a reaction chamber containing a susceptor that supports the substrate wafer during the deposition of the layer of semiconductor material. The substrate wafer is transported into the reaction chamber through a slit-valve door and a slit-valve tunnel. The process gas is conducted through gas supply lines from a gas inlet to a gas outlet. The substrate wafer is heated to deposition temperature by thermal radiation.

[0007] Base material for the electronics industry must be as free as possible from foreign substances that could impair the function of electronic components. This includes, in particular, metallic impurities. To meet this requirement even under the prevailing deposition conditions, such as the deposition temperature, components of the device such as the base ring, the gas inlet, the gas outlet, the gas supply lines, the exhaust lines (including the bellows and cone), the slit valve door, and the slit valve tunnel are generally made of stainless steel.

[0008] Although stainless steel is considered to be particularly corrosion-resistant, it is desirable to prevent metallic contaminants such as iron from migrating from the stainless steel into the layer of semiconductor material that is deposited on the substrate wafer.

[0009] The object of the invention is achieved by an apparatus for depositing a layer of semiconductor material on a substrate wafer, comprising a base ring between an upper and a lower dome; a susceptor for supporting the substrate wafer during the deposition of the layer; a gas inlet and a gas outlet as well as gas feed lines for conducting process gas over an upper side surface of the substrate wafer; a slit valve tunnel and a slit valve door; and a lifting and rotating device for lifting and rotating the susceptor and the substrate wafer, characterized in that one or more components of the apparatus which consist of stainless steel are covered by an amorphous layer which contains silicon and hydrogen.

[0010] It has been discovered that certain amorphous coatings for stainless steel are particularly suitable for the intended protection of the substrate wafer with the deposited layer of semiconductor material from contamination. These are coatings for stainless steel that are themselves produced by thermally induced chemical vapor deposition and contain silicon and hydrogen. Preferably, at least one component of the device made of stainless steel is coated with the coating for stainless steel, at least on a surface exposed to the process gas during the deposition of the layer of semiconductor material on the substrate wafer. Preferably, at least one component such as the base ring, the gas inlet, the gas outlet, the gas supply lines, the slit valve door, the slit valve tunnel, and the lifting and rotating unit for lifting and rotating a susceptor and the substrate wafer is coated with this coating.It is particularly preferred if all or almost all components of the device which are made of stainless steel and which come into contact with process gas under the deposition conditions are covered with the coating for stainless steel.

[0011] The coating is preferably hydrogenated amorphous silicon (a-Si:H) or (a-Si x Ci- x :H), particularly preferably a functionalized silica-like coating (a-SiO x :CH yA stainless steel coating made of hydrogenated amorphous silicon is offered, for example, under the Silicolloy® brand by SilcoTek Corp, and under the SilCor®SiC brand by PT&B SILCOR GmbH, and a functionalized silica-like coating is offered under the Dursan® brand, also by SilcoTek Corp. The stainless steel is preferably coated using CVD (chemical vapor deposition) or PCVD (plasma activated CVD). One such method for applying such a coating to stainless steel is described, for example, in EP 2 988 327 A1.

[0012] The invention also relates to a method for depositing an epitaxial layer of semiconductor material on a substrate wafer, wherein the substrate wafer is coated in a device with the epitaxial layer having the properties described above.

[0013] The substrate wafer is preferably a semiconductor wafer made of monocrystalline silicon, on which a layer of monocrystalline silicon is epitaxially deposited under atmospheric pressure. The deposition temperature is preferably 1000°C to 1300°C. The substrate wafer and / or the epitaxial layer can be doped with an electrically active dopant. The dopant type (p-type, n-type) can be the same or different. The substrate wafer preferably has a diameter of at least 200 mm, particularly preferably at least 300 mm.

[0014] The following description refers to drawings.

[0015] Fig. 1 shows some features of the device with which the invention is concerned in a sectional view.

[0016] Fig. 2 shows the results of lifetime measurements of minority charge carriers using pPCD measurement (microwave photoconductivity decay).

[0017] Symbol list:

[0018] 1 upper dome

[0019] 2 lower dome

[0020] 3 Device

[0021] 4 Substrate disc

[0022] 5 Susceptor

[0023] 6 lamps

[0024] 7 Base ring

[0025] 8 Gas inlet for process gas

[0026] 9 Gas inlet for purge gas

[0027] 10 Gas outlet for process gas

[0028] 11 Gas outlet for purge gas pPCD lifetime values ​​measured by pPCD measurement

[0029] N Number of measured substrate wafers with deposited epitaxial layer

[0030] Fig. 1 shows some features of the device with which the invention is concerned in a sectional view. The device 3 comprises a base ring 7, an upper and a lower dome 1, 2. Lamps 6 are arranged above the upper dome 1 and below the lower dome 2 in order to heat the substrate wafer to deposition temperature. During the deposition of a layer, the substrate wafer 4 lies on a susceptor 5, which itself is supported by susceptor support arms. The susceptor support arms are part of a lifting and rotating device for lifting and rotating the susceptor and the substrate wafer. Process gas is introduced into the device 3 via gas supply lines and through a gas inlet 8 and is discharged from the device through a gas outlet 10.The embodiment shown further comprises a further gas inlet 9 and a further gas outlet 11 for directing purge gas through the area under the susceptor during the process of depositing the layer on the substrate wafer.

[0031] Example:

[0032] The exemplary embodiment shows that a beneficial effect can be observed even when the application of coated stainless steel components is limited to coated gas supply lines and a coated exhaust line. An epitaxial layer of single-crystal silicon was deposited on substrate wafers made of single-crystal silicon with a diameter of 300 mm in a Centura® device from Applied Materials, Inc. During one series of tests, the surfaces of the gas supply lines and the first meter of the exhaust line (including bellows and cone) that came into contact with the process gas were coated with a layer of Dursan®, during a second series of tests they were coated with silicon dioxide, and during a third series they were uncoated in their original condition with a stainless steel surface. At the beginning of each series of tests, the device was in a freshly serviced condition.

[0033] After deposition of the epitaxial layer, the lifetime of minority charge carriers was determined by pPCD of the product wafers.

[0034] In Fig. 2, the measured pPCD values ​​are plotted against the number N of measured substrate wafers with a deposited epitaxial layer. Longer lifetimes were measured for the substrate wafers with an epitaxial layer produced according to the invention, and a set threshold (dashed line) was reached more quickly, suggesting that fewer impurities such as iron were released and absorbed into the epitaxial layer.

Claims

6 Patent claims 1. Device for depositing a layer of semiconductor material onto a substrate disk, comprising a base ring between an upper and a lower dome; a susceptor as a support for the substrate disk during the deposition of the layer; a gas inlet and a gas outlet, an exhaust line and gas supply lines for directing process gas over an upper side surface of the substrate disk; a slotted valve tunnel and a slotted valve door; and a lifting and rotating device for lifting and rotating the susceptor and the substrate disk, characterized in that one or more components of the device, which are made of stainless steel, are covered by an amorphous layer containing silicon and hydrogen.

2. Device according to claim 1, characterized in that the components made of stainless steel are the base ring, the gas inlet, the gas outlet, the gas supply lines, the exhaust line including a bellows and a cone, the slotted valve tunnel, the slotted valve door and the lifting and rotating device.

3. Device according to claim 1 or claim 2, characterized in that it is designed as a single-disk reactor.

4. Device according to one of claims 1 to 3, characterized in that it is designed for depositing an epitaxial layer on the substrate disk under normal pressure.

5. Method for depositing an epitaxial layer of semiconductor material onto a substrate disk, characterized in that the substrate disk is coated with the epitaxial layer in a device according to one of claims 1 to 4.

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