The disclosure relates to a method of manufacturing semiconductor chips for a liquid discharge head.
In many cases, semiconductor chips are manufactured in the manner described below. Elements and the like to be mounted on a plurality of semiconductor chips are collectively formed on a single substrate named a wafer, and then the substrate is cut and split into the plurality of semiconductor chips.
Japanese Patent Application Laid-Open No. 2005-268752 discusses a method known as laser stealth dicing as a method for cutting the substrate as described above. By the method, a laser beam is condensed and focused at a point in the substrate to metamorphose a property inside, and then the substrate is split using cracks formed from the modified portion as a starting point by applying external force to the substrate. Japanese Patent Application Laid-Open No. 2005-268752 features a plurality of the modified portions formed in a thickness direction of the substrate to cut the substrate in a direction inclined with respect to a crystal orientation plane of the substrate without compromising cutting precision.
However, the number of times the laser beam is irradiated needs to be increased to form the plurality of modified portions in the thickness direction of the substrate. This requires a longer time for cutting the substrate, and thus results in a low productivity.
To address this problem, Japanese Patent Application Laid-Open No. 2014-220403 discusses the following method. A trench is formed through etching in a surface provided with an electrode of a substrate. Then, the substrate is irradiated with a laser beam from a rear surface to metamorphose the property inside and cut at a portion where the thickness is small due to the trench. By this method, the thickness of the substrate is reduced at the portion to be cut. Thus, the number of modified portions formed in the thickness direction can be reduced, so that the number of times the laser beam is irradiated can be reduced.
The method discussed in Japanese Patent Application Laid-Open No. 2014-220403 involves forming the trench on the surface on which the electrode is formed. Therefore, an area for forming the trench needs to be secured, which reduces a freedom in designing the semiconductor chip.
The laser beam is irradiated onto the rear surface opposite to the surface on which the electrode is formed with a dicing tape attached on the surface on which the electrode is formed. This dicing tape needs to be peeled off after the cutting. When the method discussed in Japanese Patent Application Laid-Open No. 2014-220403 is employed for a method of manufacturing semiconductor chips for a liquid discharge head, the dicing tape is attached on a channel forming member provided on an energy generating element on the substrate. In many cases, the channel forming member is subjected to a surface treatment to have high water repellency. The dicing tape attached to this surface may degrade the water repellency and adhesive may remain on the surface of the channel forming member.
According to an aspect of the disclosure, a method of manufacturing a plurality of semiconductor chips for a liquid discharge head is a method of manufacturing a plurality of semiconductor chips for a liquid discharge head from a substrate by cutting the substrate along intended cutting portions of a linear form, the substrate including a plurality of energy generating elements configured to generate energy used for discharging liquid, a plurality of liquid flow paths through which the liquid is supplied to the energy generating elements, a plurality of discharge ports through which the liquid is discharged, a first surface on which the energy generating elements are disposed, and a second surface which is a rear surface of the first surface. The method includes forming trenches of a linear form through etching from the second surface along the intended cutting portions, forming modified portions in the substrate by irradiating a laser beam from the first surface side along the intended cutting portions, and splitting the substrate into the plurality of semiconductor chips for a liquid discharge head, by cutting the substrate with stress applied to the modified portions. The intended cutting portions include inclined portions extending in a direction inclined with respect to a crystal orientation plane of the substrate and uninclined portions extending in a direction along the crystal orientation plane of the substrate. The trenches are formed at least along the inclined portions.
Further features and aspects of the disclosure will become apparent from the following description of numerous example embodiments with reference to the attached drawings.
Various example embodiments of the disclosure are described below with reference to the attached drawings. In this specification and the figures, redundant description may be omitted by denoting components having the same function with the same reference numeral.
The disclosure can achieve a method of manufacturing semiconductor chips for a liquid discharge head in which high cutting precision can be maintained while the design freedom is guaranteed, the number of times the laser beam is irradiated can be reduced, and the water repellency of the channel forming member can be maintained.
A first example embodiment is described below.
An intended cutting portion is regarded as being inclined with respect to the crystal orientation plane when an angle of 3° or more is formed between an extending direction of the intended cutting portion and the crystal orientation plane. In the silicon substrate used in the present example embodiment, an angle between the extending direction of the intended cutting portion and a (110) plane A axis is defined as α and an angle between the extending direction of the intended cutting portion and a (110) plane B axis is defined as β. An angle of 3° or more is formed between the intended cutting portion and the crystal orientation plane when each of α and β is 3° or more. In an example illustrated in
The method of manufacturing semiconductor chips according to the first example embodiment of the disclosure includes preparing the substrate 1 provided with a plurality of energy generating elements 31 and metal wires 32 (
The method according to the present example embodiment further includes forming a trench 33 of a linear form, through etching from the second surface 12 of the substrate 1 (
The method of manufacturing semiconductor chips further includes forming a plurality of second liquid supply paths 56 from the first surface 11 (
The method of manufacturing semiconductor chips further includes forming liquid flow paths 52 and discharge ports 53 on the substrate 1 by using channel forming members 51 (
The method of manufacturing semiconductor chips further includes forming modified portions 66 in the substrate 1 by irradiating a laser beam 65 along the intended cutting portions 611 and 612 (
The method of manufacturing semiconductor chips further includes splitting the substrate 1 with cracks formed from the modified portions 66 as a starting point by applying stress on the modified portion 66 (
In the method of manufacturing semiconductor chips for a liquid discharge head according to the present example embodiment, a cutting precision of ±3 μm was achieved for the intended cutting portion 611 as the uninclined portion and a cutting precision of ±6 μm was achieved for the intended cutting portion 612 as the inclined portion.
In a comparative example, the silicon substrate 1, having a thickness of 725 μm with no trench 33 formed was cut with the laser beam irradiated six times at different depths in the thickness direction using laser stealth dicing. In this comparative example, the cutting precision for the intended cutting portion 611 was ±5 μm, and the cutting precision for the intended cutting portion 612 was ±15 μm.
Thus, it has been confirmed that the cutting precision can be largely improved by the method of manufacturing semiconductor chips for a liquid discharge head according to the present example embodiment. Furthermore, the cutting precision was improved although the number of times the laser beam is irradiated was reduced, which is five times in the present example embodiment. It may be because developing directions of the cracks between the modified portions 66 can be more easily controlled since the thickness a at the portion of the substrate 1 to be cut is thin, that is a=325 μm, so that a distance between the modified portions 66 is about 120 μm to about 65 μm.
According to the present example embodiment, the cutting precision can be improved without increasing the number of times the laser beam is irradiated, by decreasing the times of the laser beam emission while a higher productivity is achieved depending on conditions. Furthermore, an area for forming the trench is not required on the first surface 11 because the trench 33 is formed on the second surface 12. This configuration requires no dicing tape to be attached on the channel forming member 51, and thus the surface of the channel forming member 51 is free of degradation of the water repellency and the adhesive does not remain thereon.
A second example embodiment is described below. In a method of manufacturing semiconductor chips for a liquid discharge head according to the second example embodiment of the disclosure, the substrate 1 is cut at the intended cutting portions 611 and 612 laid out as illustrated in
The trenches 33 may be formed along both the intended cutting portions 611 as the uninclined portion with respect to the crystal orientation plane and the intended cutting portions 612 as the inclined portions. However, in this configuration, the strength of the substrate 1 may be degraded beyond a tolerable level, depending on the depth and the number of the trenches 33.
As described above, the substrate 1 includes the intended cutting portions 611 as the uninclined portions and the intended cutting portions 612 as the inclined portions. The intended cutting portions 612 as the inclined portions are easy to cut along the crystal orientation plane and thus show a higher cutting precision than the uninclined portions. Thus, according to the present example embodiment, the depth of the trench 33 formed along the intended cutting portion 611 as the uninclined portion is set smaller than that formed along the intended cutting portion 612 as the inclined portion. More specifically, the depth of the trench 33 formed along the intended cutting portion 611 is 150 μm, whereas the depth of the trench 33 formed along the intended cutting portion 612 is 400 μm. In this configuration, the laser beam was irradiated six times onto the intended cutting portion 611 on which the trench 33 was formed, and was irradiated five times onto the intended cutting portion 612 on which the trench 33 was formed.
In the present example embodiment, the cutting precision was ±6 μm at the intended cutting portion 612 as the inclined portion, and the cutting precision was ±4 μm at the intended cutting portion 611 as the uninclined portion. Thus, while the cutting precision at the intended cutting portion 611 was lower than the first example embodiment at the intended cutting portion 611 because the shallower trench 33 was formed, but the cutting precision was still higher than ±5 μm of the case where no trench 33 is formed.
Since the shallower trench 33 was formed along the intended cutting portion 611 as the uninclined portion, decrease of the strength of the substrate 1 can be smaller compared with the first example embodiment.
Further, when the cutting precision at the intended cutting portion 611 as the uninclined portion is sufficiently high and thus requires no improvement, the trench 33 may be formed only along the intended cutting portion 612 as the inclined portion, and does not need to be formed along the intended cutting portion 611 as the uninclined portion. This configuration can further suppress decrease of the strength of the substrate 1. In this configuration, the intended cutting portion 611 as the uninclined portion is in close contact with the dicing tape, and thus the intended cutting portion 611 may be cut by a method other than the laser stealth dicing such as blade dicing.
A third example embodiment is described below. A method of manufacturing semiconductor chips for a liquid discharge head according to the third example embodiment of the disclosure is different from the first and the second example embodiments in a layout of the intended cutting portions.
As another solution for preventing the excessive decrease in the strength of the substrate 1 as a result of forming the trench 33, the intended cutting portion may be discontinuously formed. In the layout illustrated in
A fourth example embodiment is described below. A method of manufacturing semiconductor chips for a liquid discharge head according to the fourth example embodiment of the disclosure further improves the cutting precision of the substrate 1 in the method according to the third example embodiment. A difference from the third example embodiment is mainly described below.
In view of the above, the trench 33 is formed to be longer than the intended cutting portion 612. Thus, the error in the irradiated position of the laser beam is considered in advance, so that the trench 33 and the line 62 irradiated with the laser beam can be in contact with each other even when the irradiated position of the laser beam is deviated. In this case, the trench 33 enters an adjacent chip 22 (
The disclosure is described above with reference to the example embodiments. However, the disclosure is not limited to the example embodiments. The configurations and the details of the disclosure can be modified in various ways within the technical scope of the disclosure and the general knowledge of a person skilled in the art.
For example, in the example embodiment described above, the substrate 1 is a silicon substrate and the crystal orientation plane is a (110) plane. However, the disclosure is not limited to the example. For example, the substrate 1 may be a semiconductor substrate other than the silicon substrate. In such a case, the crystal orientation plane may be set to be a plane along which cutting can be easily performed in accordance with a property of a semiconductor of this substrate.
While the disclosure has been described with reference to example embodiments, it is to be understood that the invention is not limited to the disclosed example embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2016-122469, filed Jun. 21, 2016, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2016-122469 | Jun 2016 | JP | national |