JPS60234850A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To make it possible to stably keep an initial good liquid droplet forming characteristic over a long period of time by imparting excellent synthetic durability to the titled recording head in frequent repeated use or long-time continuous use, by forming an upper layer by a bias sputtering method. CONSTITUTION:When RF power of 700W is applied to an SiO2 target with a dimension of phi8 inch and an SiO2 layer is formed by changing support bias in a range of 0-300V, the inclination at a step part becomes gentle as bias voltage becomes larger and the result of etching treatment shows a value almost equal to the etching speed in a flat part in all parts when no bias voltage is applied. A film forming speed is reduced as bias voltage is applied to a support but the inclination of the step part becomes gentle as bias is increased. From the relation of the effect of bias applied to the support and the required time of a film forming process by a film forming speed, bias is -100V--250V more pref.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid jet recording head that performs recording by jetting liquid and forming flying droplets, and more specifically, a liquid jet recording head in which an upper layer is formed by bias sputtering. Regarding.

The liquid jet recording method has recently attracted attention because it generates negligible noise during recording and can record on so-called plain paper.

Among them, for example, the liquid jet recording method described in JP-A No. 54-51837 is different from other liquid jet recording methods in that it applies thermal energy to the liquid to obtain the driving force for ejecting droplets. They have different characteristics. In other words, in this recording method, the liquid subjected to the action of thermal energy causes a sudden change in volume due to a change in state, and this acting force causes the liquid to be ejected from the orifice at the tip of the recording head, forming flying droplets. The droplets adhere to the recording member and recording is performed.

The heat generating element in the present liquid jet recording head is composed of a heat generating resistive layer and at least a pair of opposing electrodes electrically connected to the heat generating resistive layer, and the surface of the heat generating element at least in the portion that contacts the liquid. The upper part chemically and physically protects these heat generating elements from the liquid used, and prevents short circuits between the electrodes through the liquid.
Furthermore, an upper layer consisting of a single layer or a plurality of layers is provided in order to prevent galvanic corrosion caused by electricity flowing from the electrode to the liquid.

In the case of a multi-orifice type liquid jet recording head, in order to simultaneously form a large number of fine electrothermal transducers on the substrate, each layer is formed on the substrate during the manufacturing process, and the formed layers are At the stage where the upper layer is formed by repeatedly removing a portion of Coverability of the upper layer (S
tep coverage) has become important. In other words, if the coverage of this stepped portion is poor, liquid will penetrate into that portion, causing electrolytic corrosion or electrical breakdown. In addition, if the upper layer to be formed has a high probability of having defects due to the manufacturing method, liquid may penetrate through the defects, which can significantly shorten the life of the electrothermal converter. It has become.

For these reasons, the upper layer must have good coverage in the step part, and the probability that defects such as pin poles will occur in the formed layer is low (even if they occur, it is practically negligible). Or even less is required.

Conventionally, the upper layer is generally made of silicon dioxide (SiOz), silicon nitride, silicon carbide, etc. by vacuum evaporation method, CVD method,
It was formed by sputtering method. However, these forming methods could not fully satisfy the above requirements.

For example, in the vacuum evaporation method, the energy of the flying molecules or atoms is only the thermal energy during evaporation, resulting in poor adhesion to the substrate.Also, since the area of the evaporation source is small, shadows tend to form at stepped portions, resulting in poor coverage. . Furthermore, when depositing a thick film of several micrometers, it is difficult to control the deposition rate at a constant rate, and when the deposition rate changes, the degree of decomposition of the sample changes and the composition of the film becomes non-uniform. on the other hand,
Although the CVD method provides good coverage, the formed film is susceptible to thermal stress (and is prone to cracking).

Therefore, as described above, liquid permeates through the cracks, causing electrolytic corrosion or electrical breakdown. In addition, although the conventional sputtering method has good adhesion, heat resistance, and coverage, the film lacks denseness in the stepped areas and cannot provide sufficient shielding from the liquid used, so long-term reliability remains a problem. .

As described above, a liquid jet recording head with excellent overall durability has not yet been proposed.

The present invention has been developed in view of the above points, and has excellent overall durability in frequent repeated use and long-term continuous use, and maintains good initial droplet formation characteristics over a long period of time. The main object of the present invention is to provide a liquid jet recording head that can be stably maintained.

Another object of the present invention is to provide a liquid jet recording head that is highly reliable in manufacturing and processing.

The object of the present invention is achieved by the following liquid jet recording head.

A liquid jet recording head having an orifice for ejecting flying droplets, an energy generator for generating energy used to form the droplets, and an upper layer formed above the energy generator. A liquid jet recording head characterized in that the upper layer is formed by a bias sputtering method.

Hereinafter, the liquid jet recording head of the present invention will be specifically explained with reference to the drawings. FIG. 1(a) is a plan view of a substrate in the vicinity of a heat generating portion of a conventional liquid jet recording head, and is a partial cross-sectional view when the first rotation is taken at a portion indicated by a dashed line XX'. An electrothermal transducer 4 is constructed by forming a heating resistance layer 2 and electrodes 3, 3' on a support 1. An upper layer 5 is formed to isolate the electrothermal converter 4 from the liquid used.

The problems when the upper layer 5 is formed by the conventional sputtering method are as described above. When the etching rate of the upper layer made of 5i02 was measured in flat areas and stepped areas using a hydrofluoric acid-based etching solution, the etching rate of the stepped areas was 13 times that of the flat areas. Ta.

In a liquid jet recording head that has an upper layer formed by a conventional sputtering method, when used repeatedly over a long period of time, the liquid shielding performance deteriorates significantly because the film is porous at the stepped portions as described above. This is because there is.

The present inventors have discovered that the film can be made denser at the stepped portion by a so-called bias sputtering method in which sputtering is performed while applying a bias to the support.

FIG. 2(a) is a cross-sectional view of an electrode portion coated with a conventional Si02 layer, and FIG. 2(b) is a schematic cross-sectional view of an electrode portion coated with a Si02 layer by the bias sputtering method according to the present invention. FIG.

When no bias is applied to the support, the Si02 layer 8 laminated on the electrode 7 and the stepped portion of the heat generating resistor layer 60 produces a so-called "constriction" in the shaded area A in the figure, and this part is smaller than other parts. It was revealed by measuring the etching rate using a hydrofluoric acid etching solution that the film was porous.

Therefore, we applied 700 W of RF power to a 98-inch Si 02 target and varied the support bias from 0 to 360 V to form a Si 02 layer, as shown in Figure 2(b).
As shown in , the slope at the step part becomes more gradual as the bias voltage increases, and as a result of the same etching process as described above, the etching rate at the flat part when no bias is applied to all parts is As shown in Figure 3, the film formation rate decreased as a bias was applied to the support, but the slope of the step shown in Figure 2 was reduced by increasing the bias. It will be smoother if you do that.

In FIG. 3, the vertical axis shows the film formation rate and the horizontal axis shows the support bias.

From the relationship between the effect of applying bias to the support and the time required for the film forming process depending on the film forming rate, the bias is preferably 50 to -
More preferably 100V to 1250V is more appropriate than 300V.

As mentioned above, the upper layer formed by bias sputtering has excellent density at the step part, and even if small dust etc. adheres to the support, the coating is good, so there are no pinholes, and it is not commonly used. A decrease in pinhole density was also confirmed when measuring pinhole density using the copper durayon method using a methanol solution. Furthermore, even in the case where a film having an anti-cavitation effect is laminated on the upper layer to protect the upper layer from cavitation that occurs when the liquid foams and contracts, the upper layer formed by bias sputtering is Since the slope is gentle, it has great effects such as improving the coverage of the anti-cavitation film.

The material forming the upper layer is not limited to silicon dioxide (Si02), but includes, for example, titanium oxide, vanadium oxide, niobium oxide, molybdenum oxide, tantalum oxide,
Transition metal oxides such as tungsten oxide, chromium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, yttrium oxide, and manganese oxide, as well as aluminum oxide,
Calcium oxide, strontium oxide, barium oxide,
Metal oxides such as silicon oxide other than 5i02 and their composites, high resistance nitrides such as silicon nitride, aluminum nitride, boron nitride, tantalum nitride, and these oxides,
Examples of thin film materials include nitride composites and semiconductors such as amorphous silicon and amorphous selenium, which have a low resistance in bulk but can become high in resistance during the manufacturing process, and their layer thickness is generally 0.1 μm to 4 μm. , preferably 0.1 μm to 3 μm, more preferably 0.1”’ 2
It is preferable that it be set as It m.

The layer thickness is determined by the voltage applied to form the flying droplets. For example, when applying a voltage with some margin, a layer thickness of up to 3 μm is selected, and when the voltage is limited to a necessary and sufficient voltage, a layer thickness of up to 2 μm is selected. etc. can be used.

[Brief explanation of drawings]

FIG. 1(a) is a plan view of the substrate in the vicinity of the heat generating part of a conventional liquid jet recording head, and FIG.
FIG. 3 is a partial cross-sectional view taken along the dashed-dotted line XX' in a). FIG. 2(a) is a partial cross-sectional view of the upper layer at the stepped portion formed by the electrode and heat-generating resistor layer formed by the conventional sputtering method, and FIG. 2(b) is a partial cross-sectional view of the electrode and heat-generating resistor layer formed by the bias sputtering method of the present invention. FIG. 3 is a schematic partial cross-sectional view of the upper layer at the stepped portion, and is a graph showing the relationship between the support bias and the film formation rate by bias sputtering in the present invention. 1...Substrate 2...Heating resistance layer 3.3'...Electrode 4...Electrothermal converter 5...Upper layer 6...Heating resistance layer 7...Electrode 8.8' ...Upper layer patent applicant Canon Co., Ltd. agent Tadashi Wakabayashi

Claims (1)

[Claims] In a liquid jet recording head, the liquid jet recording head has an orifice for ejecting flying droplets, an energy generator that generates energy used to form the droplets, and at least an upper layer formed on the energy generator. A liquid jet recording head characterized in that the upper layer is formed by a bias sputtering method.