TW201738959A - Method for pre-aligning wafer before etching wafer by etching a silicon substrate along the crystal orientation to form an alignment slot - Google Patents

Abstract

This invention relates to a method for pre-aligning a wafer before etching the wafer. The method mainly comprises the following steps: etching a silicon substrate along the crystal orientation to form an alignment slot; making a photomask align with the alignment slot in advance in a subsequent process by the alignment slot formed by this invention to ensure that the photomask is precisely aligned with the crystal orientation of the silicon substrate, so that the condition of short circuit, circuit breaking or poor electrical property of a subsequent electronic product is avoided, which is due to incapability of accurately forming a pattern of the photomask on a relative position of the silicon substrate in the subsequent process by errors between a preset crystal lattice size of the silicon substrate and an actual crystal lattice size, because the photomask is not precisely aligned with the silicon substrate in the subsequent process of the silicon substrate.

Description

Pre-alignment method before wafer etching

The present invention is a pre-alignment method before wafer etching, in particular, a method of forming an alignment groove along the crystal orientation of the germanium substrate through an etching step, so that the photomask and the germanium substrate can be more accurately aligned.

When the base material is produced, the manufacturer will manufacture the tantalum substrate with different crystal structure arrangement according to the subsequent application of the tantalum substrate, and the arrangement of the crystal structure has directionality, which is called crystal orientation, for example, <100> The crystal orientation system is used to manufacture a metal-oxide-semiconductor (MOS) device and a <111> crystal orientation for manufacturing a bipolar element, and in order to distinguish the crystal orientation, after the ingot is fabricated, The ingot grinds a notch or a flat edge corresponding to the crystal orientation to achieve the purpose of discriminating the crystal orientation, for example, grinding the gap with a <110> crystal orientation for the <100> crystal orientation. Then, the ingot was sliced into a plurality of tantalum substrates. Then, after the notch of the ruthenium substrate is aligned with the notch of the reticle, the pattern of the reticle is formed on the ruthenium substrate, and then the ruthenium substrate is cut into a plurality of dies, and the ruthenium is formed. A component of an electronic product.

Next, referring to FIG. 1A and FIG. 1B, when the crucible substrate 10 is fabricated, the crystal orientation cannot be precisely controlled due to the existing technique of manufacturing the ingot, and therefore, the predetermined crystal orientation 12 and the actual crystal orientation 13 will have errors, and When the ingot is fabricated, the ingot will be ground in accordance with the predetermined crystal orientation 12, causing the subsequent process to be greatly affected.

In detail, when the ingot has the aforementioned crystal orientation error, after the subsequent slicing is the crucible substrate, the notch 11 of the crucible substrate is aligned with the notch of the photomask to form the pattern of the photomask on the crucible substrate. At this time, the pattern will not be properly formed at the corresponding position of the tantalum substrate, so that the lattice size defined on the tantalum substrate is different from the expected lattice size, so that the yield of the tantalum substrate is lowered.

Furthermore, as the size of electronic products is becoming smaller, the lattice needs to be reduced. If the reticle and the enamel substrate are not precisely aligned, and the pattern is formed on the dies, the pattern on the dies will be caused. Unlike the graphic design of the reticle, when it is applied to electronic products, it will cause short circuit, open circuit or poor electrical condition, so that the electronic product cannot operate normally.

Accordingly, in the prior art, the gap of the mask is manually aligned with the notch of the crucible substrate, and then the photoresist on the germanium substrate is exposed through the mask through the yellow light, and then the crucible is exposed. The photoresist on the substrate is subjected to a developing process, and the pattern of the mask is developed on the photoresist. Further, the pattern is placed on the photoresist to etch the substrate with an etchant to form a pattern of the mask. The corresponding position of the crucible substrate is followed by dividing the crucible substrate into a plurality of crystal grains.

Or, in a more precise manner, the image of the reticle is imaged through a photosensitive coupled device (CCD) by means of optical alignment, and the pattern on the reticle and the gap of the reticle are calculated. Corresponding coordinate position, then moving the substrate on which the substrate is placed so that the notch of the base material corresponds to the notch of the mask, according to the corresponding coordinate position of the pattern of the mask and the notch of the mask, A pattern is formed on the substrate.

In addition, the prior art also divides the germanium substrate into a plurality of detection regions, and the detection region has a plurality of crystal grains, and then, by comparing the patterns of the photomasks with each of the detection regions, the detection is measured. The offset between the area and the pattern of the reticle, and the correction formula is generated according to the offset, respectively. To make the correction formula more accurate, the average value of the detection area offset of a large number of 矽 substrates is measured, resulting in more accurate The correction formula improves the offset between the die and the reticle so that the pattern of the reticle can be precisely defined on the ruthenium substrate.

It can be seen from the above that the artificial alignment and the optical alignment are based on the gap of the tantalum substrate, and the correction formula is corrected by the statistical formula, however, the artificial alignment and the optical alignment In the way, if the gap between the substrate and the crystal orientation is in the process of fabricating the germanium substrate, there is an error with the predetermined crystal orientation, and the artificial alignment or the optical alignment is based on the gap, and further, the germanium substrate is etched. There will be an error between the predetermined lattice size and the actual lattice size, resulting in poor electrical properties of the subsequent electronic products, and the correction formula requires a relatively accurate correction formula to be calculated by the offset between the large number of grooves and the mask. It estimates the possible offsets in a statistical way, and can't really make each piece of the substrate to be accurately aligned with the mask. There is also an error between the predetermined lattice size and the actual lattice size, resulting in subsequent The problem of poor electrical properties of electronic products.

Accordingly, if the mask is aligned with the crucible substrate by the gap of the crucible substrate, the pattern of the mask is formed at the relative position of the crucible substrate, which may cause the crystal of the mask and the crucible substrate. The subsequent process is performed for the inaccurate alignment, so that there is an error between the predetermined lattice size and the actual lattice size, so that the pattern of the reticle cannot be correctly formed on the relative position of the ruthenium substrate, resulting in subsequent electronic products. A short circuit, open circuit, or poor electrical condition.

It can be seen from the above that if the photomask and the crucible substrate are not precisely aligned, there will be an error between the predetermined lattice size and the actual lattice size, so that the pattern of the photomask cannot be correctly formed on the relative position of the crucible substrate, resulting in subsequent The short circuit, open circuit or poor electrical condition of the electronic product; therefore, the main purpose of the creation is a pre-alignment method before wafer etching, so that the crystal orientation of the photomask and the germanium substrate can be accurately aligned, and the problem is solved. Accurate alignment, resulting in short-circuit, open circuit or poor electrical problems in electronic products.

In order to solve the above problems, the present invention is a pre-alignment method for wafer etching, comprising the steps of: providing a germanium substrate; performing an etching step on the germanium substrate to form the germanium substrate along the crystal orientation thereof An alignment slot.

Because the creation system creates an alignment groove formed along the crystal orientation of the crucible substrate by etching, thereby using the alignment groove as a reference reference for the subsequent process, the photomask can be more accurately combined with the crucible. The crystal orientation of the substrate is aligned to reduce the error between the predetermined lattice size and the actual lattice size of the ruthenium substrate, and the ruthenium substrate can accurately align the reticle and the ruthenium substrate, and solve the short circuit, open circuit or electricity of the electronic product. Bad sex.

The technical means adopted by the present invention for achieving the intended purpose of creation are further explained below in conjunction with the drawings and the preferred embodiment of the present invention.

First, referring to FIG. 2, the pre-alignment method before wafer etching of the present invention provides a substrate (S21), and then an etching step is performed on the germanium substrate to cause the germanium substrate along the crystal orientation thereof. An alignment groove is formed (S22).

Specifically, please refer to FIG. 3A and FIG. 3B together to provide a crucible substrate 10 having a notch 11 and an actual crystal orientation 30 through which an etching step is performed on the crucible substrate 10. The tantalum substrate 10 forms an alignment groove 301 along its actual crystal orientation 30. In the preferred embodiment, the tantalum substrate 10 is a tantalum substrate.

Next, referring to FIG. 4, the foregoing etching step includes: providing an alkaline etchant (S41); then, performing a wet etching step on the germanium substrate with the alkaline etchant to actually along the germanium substrate The crystal orientation is etched (S42).

In addition, referring to FIG. 5, before performing the etching step, performing the following steps: performing a chemical vapor deposition step on the germanium substrate to form an insulating layer on the germanium substrate (S51); After the insulating layer is formed, a yellow light step is performed on the germanium substrate to form an alignment pattern on the insulating layer (S52); then, the insulating layer is subjected to a dry etching step to remove the pair of the insulating layer Quasi-graphics (S53).

Furthermore, referring to FIG. 6, the yellow light step includes: applying a first photoresist on the insulating layer, and soft-baking the first photoresist (S61); providing a photomask to the first Above the photoresist (S62); exposing the first photoresist to an ultraviolet light according to the alignment pattern of the mask (S63); after exposing, developing the first photoresist with a developer The alignment pattern of the photomask is formed on the first photoresist (S64).

Further, referring to FIG. 7, the dry etching step includes: reacting a sulfur fluoride gas with the insulating layer of the germanium substrate to etch the insulating layer (S71); after performing etching, proceeding After the etching, the insulating layer is etched by stopping the sulfur fluoride gas with a monofluorocyclobutane gas, and the alignment pattern is formed by the insulating layer (S72).

Further, referring to FIG. 8, after forming the alignment groove, a second photoresist is coated on the germanium substrate, and the second photoresist is soft baked (S81); then, the alignment pattern is performed. Aligning with the alignment groove of the crucible substrate (S82); after alignment, exposing the second photoresist to an ultraviolet light according to a pattern of the mask (S83); after exposure, The second photoresist is developed by a developer to form the pattern of the mask on the second photoresist (S84) for fabricating an insulating mask of a second etching pattern.

The alkaline etchant described above is one of potassium hydroxide (KOH), tetramethylammonium hydroxide (TMOAH), ethylenediamine-catechol (C6H4) or sodium hydroxide (NaOH), and the above The sulfur fluoride gas may be sulfur hexafluoride gas, and the fluorocyclobutane gas may be octafluorocyclobutane gas.

For example, first, referring to FIG. 9A, a crucible substrate 10 having a notch and a <100> crystal orientation is provided, and then the crucible substrate 10 is subjected to oxidation reaction by chemical vapor deposition. An insulating layer 90 is formed on the tantalum substrate 10.

Next, referring to FIG. 9B, a photoresist 91 is coated on the insulating layer 90, and the photoresist 91 is soft baked to form a photoresist 91 on the insulating layer 90. Next, referring to FIG. 9C, a mask 92 is provided. The mask 92 has a pattern 920 and a notch (not shown). After the notch of the mask 92 is initially aligned with the gap of the crucible substrate 10, The photoresist 91 is exposed through a pattern 920 of the mask 92 by an ultraviolet light 93. After exposure, the photoresist 91 is developed by a developer to form a photoresist 902 having a pattern 920 of the mask 92.

Next, referring to FIG. 9D, a sulfur oxide gas is transmitted through the photoresist 902 having the pattern 920 of the mask 92 to react with the insulating layer 901 of the germanium substrate to etch the insulating layer 901. After the etching, the fluorinated sulfur gas is stopped, and the insulating layer 90 corresponding to the pattern is etched to form the insulating layer 901 having the pattern 920 of the mask 92. Subsequently, please refer to the figure. 9E, the <100> crystal orientation of the tantalum substrate 10 is mainly etched with potassium hydroxide to form the alignment groove 301 of the <100> crystal orientation.

After the alignment groove 301 is formed, the groove to be etched is formed by an insulating layer, yellow light, dry etching, an insulating layer mask, an alkali etching solution etching step, and a groove having a correct lattice size is etched, and The circuit pattern to be formed on the base material is formed on the base material 10 by a yellow light step. Specifically, after the alignment groove 301 is formed, the base material is coated with a photoresist, and then, After aligning the pattern and the pattern of the circuit pattern, the alignment pattern is aligned with the alignment groove, and the circuit pattern is exposed and developed on the substrate, and the circuit pattern is formed on the substrate.

Accordingly, through the etching method of the present invention, an alignment groove formed along the crystal orientation is formed on the germanium substrate, and the alignment groove is used as the alignment reference of the subsequent process, so that the photomask can be more accurately combined with the germanium base. The crystal orientation of the material is opposite, reducing the predetermined lattice size of the twin crystal material and the actual lattice size error, so that the photomask and the crucible substrate can be accurately aligned, and the problem of short circuit, open circuit or poor electrical failure of the electronic product is solved.

The above description is only a preferred embodiment of the present invention, and does not impose any form limitation on the present invention. Although the present invention has been disclosed above in the preferred embodiment, it is not intended to limit the present creation, and has any technical field. A person skilled in the art can make some modifications or modifications to equivalent embodiments by using the above-disclosed technical contents without departing from the technical scope of the present invention. The technical essence of the creation Any simple modification, equivalent change and modification of the above embodiments are still within the scope of the technical solution of the present invention.

10‧‧‧矽 substrate
11‧‧‧ gap
12‧‧‧Predetermined crystal orientation
13, 30‧‧‧ actual crystal orientation
301‧‧‧ alignment slot
90, 901‧‧‧ insulation
91, 902‧‧‧ photoresist
92‧‧‧Photomask
920‧‧‧ graphics
93‧‧‧UV light

Figure 1A is a schematic view of a predetermined crystal orientation of a tantalum substrate. Figure 1B is a schematic illustration of the actual crystal orientation of the tantalum substrate. Figure 2 is a flow chart of the creation. FIG. 3A is a schematic top view of the alignment groove of the present invention. Figure 3B is a side elevational view of the alignment slot of the present invention. Figure 4 is a flow chart of the etching process of the present author. Figure 5 is a flow chart before the etching step of the present creation. Figure 6 is a flow chart of the dry etching step of the present invention. Figure 7 is a flow chart of the steps of creating a yellow light. Figure 8 is a flow chart after the creation of the alignment groove. 9A to 9E are schematic structural views of the method of the present creation.

Claims (10)

A method of pre-alignment prior to wafer etching, comprising: providing a germanium substrate; and performing an etching step on the germanium substrate to form an alignment trench along the crystal orientation thereof. The method of pre-alignment of a wafer before etching according to claim 1, wherein the etching step comprises: providing an alkaline etchant; performing a wet etching step on the germanium substrate with the alkaline etchant The crystal orientation of the tantalum substrate is etched. The method of pre-alignment of a wafer before etching according to claim 1 or 2, wherein before performing the etching step, comprising: performing a chemical vapor deposition step on the germanium substrate to the germanium substrate Forming an insulating layer; after the insulating layer is formed, performing a yellowing step on the germanium substrate to form an alignment pattern on the insulating layer; performing a dry etching step on the insulating layer to remove the insulating layer The alignment pattern. The pre-alignment method of the wafer before the etching according to claim 3, wherein the yellowing step comprises: coating a first photoresist and soft-baking the first photoresist; providing a photomask Above the first photoresist; according to the alignment pattern of the mask, exposing the first photoresist with an ultraviolet light; after exposing, developing the first photoresist with a developer to The alignment pattern of the photomask is formed on the first photoresist. The method of pre-alignment of a wafer before etching according to claim 4, wherein the dry etching step comprises: reacting the insulating layer with the germanium substrate with a sulfur fluoride gas to perform the insulating layer Etching; after etching, the insulating layer is etched by stopping the sulfur fluoride gas with a monofluorocyclobutane gas, and the alignment pattern is formed by the insulating layer. The pre-alignment method of the wafer before the etching according to claim 5, wherein after forming the alignment trench, further comprising: coating a second photoresist on the germanium substrate, and applying the second light to the second light Resisting the soft bake; aligning the alignment pattern with the alignment groove of the crucible substrate; after aligning, exposing the second photoresist to an ultraviolet light according to a pattern of the photomask; After the exposure, the second photoresist is developed with a developer to form the pattern of the mask on the second photoresist. The method of pre-alignment of a wafer before etching according to claim 5, wherein the sulfur fluoride gas is a sulfur hexafluoride gas, and the fluorine-cyclobutane gas may be an octafluorocyclobutane gas. The method of pre-alignment of a wafer before etching according to claim 6, wherein the sulfur fluoride gas is a sulfur hexafluoride gas, and the fluorine-cyclobutane gas may be an octafluorocyclobutane gas. The method of pre-alignment of a wafer before etching according to claim 7, wherein the alkaline etchant is potassium hydroxide, tetramethylammonium hydroxide, ethylenediamine-catechol or sodium hydroxide. The method of pre-alignment of a wafer before etching according to claim 8, wherein the alkaline etchant is potassium hydroxide, tetramethylammonium hydroxide, ethylenediamine-catechol or sodium hydroxide.