KR20080073841A - Probe head and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a probe head that is a component of a probe card, and more particularly to a probe head consisting of a probe tip, a curved micro spring, a bumper, and a space transformer.

The manufacturing method disclosed in the present invention comprises the steps of forming a through hole in the active silicon of the silicon on insulator substrate composed of carrier silicon, barrier oxide film, and active silicon; Forming an inclined surface in the carrier silicon; Forming a probe tip in the through hole of the active silicon; Forming a bent microspring connected at one end to the probe tip in the carrier silicon having the inclined surface formed thereon; Forming a bumper at the other end of the microspring; Bonding pads formed on the bumper and the space transformer; Removing the silicon on insulation substrate.

Description

PROBE HEAD AND MANUFACTURING METHOD THEREFOR}

1 is an exemplary view showing a probe card of the prior patent 1;

Figure 2 is an exemplary view showing an elastic contact element of the prior patent 2,

3a and 3b is an exemplary view showing a probe head of the present invention,

Figures 4a to 4p is an exemplary view showing a probe head manufacturing process of the present invention.

** Description of symbols for the main parts of the drawing **

1: probe tip 2: bent microspring

3: bumper 4: pad

5: space transformer 6: junction

7 recessed pad 8 silicon on insulation

9: active silicon 10: barrier oxide film

11: carrier silicon 12: seed layer

13: transparent glass substrate

The present invention relates to a probe head which is a component of a probe card, and more particularly, to a probe head composed of a probe tip, a curved micro spring, a bumper and a space transformer, and a manufacturing method therefor.

As is well known, the 'probe head' is a component of a probe card that determines whether a semiconductor element is abnormal by measuring an electrical signal of the semiconductor element. One example of a probe card assembly is disclosed in US Form Factor US Pat. No. 6,246,247 (hereinafter, referred to as Patent 1).

Referring to FIG. 1, which is a representative drawing of the prior patent 1, an electrical signal flow of a probe card is schematically described as follows. The electrical signal transmitted from the outer terminal of the printed circuit board to the pad of the printed circuit board is transmitted to the pad of the semiconductor device through the space transformer, the micro spring, and the probe tip through the contact point of the interposer. Transformers, microsprings and probe tips are joined to secure electrical connections. In addition, to smoothly transmit the electrical signal, the probe tip must be pressed to the pad of the semiconductor device. The repulsive force generated is transmitted to the space transformer through the probe tip and the micro spring.

Form contact of Republic of Korea Patent No. 10-0324064 ("contact structure for microelectronic interconnection element and its manufacturing method") (hereinafter referred to as prior patent 2) elastic contact element suitable for performing a pressure connection between electronic components It is starting. Referring to Figure 2, the contact tip structure has positional (small, rigid, protruding, non-planar) contact features, such as truncated pyramid shapes, to optimize the electrical pressurization connections subsequently formed at the terminals of the electronic component. do. It also constitutes a long contact tip structure designed to function as an elastic contact element without the need to be coupled to the elastic element in use.

In the manufacturing method of the prior patent 2, it is determined that the contact tip of the truncated pyramid shape and the bent micro spring can be manufactured relatively easily, but the contact tip is continuously worn during the electrical contact of the semiconductor device, and the contact area of the tip is sharply increased. There is a disadvantage that can be increased. In addition, no method for removing the thickness deviation during plating of the bent microspring is presented, and the other end of the bent microspring is adhered to the space transformer by soldering, and thus the soldering strength is weak due to plane bonding. There is a high possibility that the micro spring is easily released. In addition, the soldering process has to use a flip chip bonding equipment, there is a disadvantage that the position accuracy is not good.

The present invention was devised to solve the above-mentioned problems, and discloses a cylindrical probe tip in which the cross-sectional area of the probe tip is similar to the cross-sectional area before wear even by the wear in the measurement. Also disclosed is an electroless plating method for improving the thickness uniformity of a curved microspring. Also disclosed is a joining method capable of precisely aligning and joining a bumper and a space transformer attached to the other side of the microspring. This provides a way to ensure reliable production of the probe head and thus to improve product yield.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. In the meantime, when it is determined that the detailed description of the known functions and configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, it should be noted that the detailed description is omitted.

The probe head disclosed in the present invention includes a cylinder-shaped probe tip, a bent microspring connected at one end to the probe tip, a bumper formed at the other end of the microspring, and a bumper bonded to a pad formed at the space transformer. Configure

In addition, the probe head fabrication method of the present invention comprises the steps of forming a through hole in the active silicon of the silicon on insulator substrate composed of carrier silicon, a barrier oxide film, and active silicon, forming a sloped surface in the carrier silicon, and Forming a probe tip in the through hole; Forming a bent microspring connected to the probe tip and one end on the inclined carrier silicon, forming a bumper at the other end of the micro spring, bonding the pad formed on the bumper and the space transformer, Removing the silicon on insulation substrate.

FIG. 3A shows a probe head coupled to a micro spring bent to a space transformer with a flat pad, and FIG. 3B shows a probe head bonded to a space transformer micro spring with a recessed pad. In the drawings, reference numeral 1 designates a probe tip, 2 is a bent micro spring, 3 is a bumper, 4 is a pad, 5 is a space transformer, 6 is a junction, and 7 is a recessed pad.

The probe tip and curved microspring of the present invention are fabricated via a silicon on insulated substrate. In the carrier silicon region, the electroplating mold for forming the bent micro spring is formed, and in the region of the active silicon on the opposite side, the electroforming mold for plating the probe tip is manufactured.

Figures 4a to 4p is a manufacturing process diagram of the probe head according to the present invention.

Reference numerals [A] to [I] in the drawings indicate a series of processes for manufacturing the probe tip. Specifically, [A] is a step of forming a pattern of the probe tip on the active silicon surface of the silicon on insulator substrate, and [B] is a dry etching of the probe tip pattern to form a hole in the active silicon to form a hole in the active layer. Forming.

[C] is a step of forming an inclined surface pattern on the carrier silicon, and [D] is a step of wet etching the carrier silicon to the barrier oxide layer surface on the carrier silicon to form an inclined surface on which the bent micro spring is to be formed.

[E] is a step of forming a silicon oxide film or a silicon nitride film on the inclined surface of the carrier silicon and the hole of the active silicon, and [F] is etching the barrier oxide film near the top of the hole where the probe tip of the active silicon is to be formed. A through hole is formed in an insulation substrate.

[G] is a step of using the hole of the active silicon as a mold for electroplating by adhering the seed substrate for electrolytic plating of the probe tip to the lower surface of the active silicon.

[H] is the step of electroplating the probe tip from the seed substrate and [I] is the step of removing the seed substrate.

The process of adhering the probe tip prepared in this process to the seed substrate is as follows. Reference numeral [J] is a step of forming a metal seed pattern on the transparent glass substrate that matches the arrangement of the probe tips.

[K] is a step of applying an ultraviolet adhesive to the glass substrate on which the metal pattern is formed, [L] is a step of bonding the glass substrate and active silicon by curing the ultraviolet adhesive by irradiating ultraviolet rays from the glass substrate.

[M] is a step of forming a seed layer for electrolytic plating of the probe tip by removing ultraviolet rays on the metal seed pattern not irradiated with an organic solvent such as alcohol or acetone.

The hole for forming the probe tip by the above-described process has a narrow and long cylindrical shape, and since the seed metal layer is present only in the lower portion of the hole, it is suitable for growing rhodium metal or palladium alloy having good abrasion resistance by electroplating.

Next, we will look at the process of manufacturing the aforementioned bent microspring. Reference numeral [N] denotes a step of applying a metal layer to the entire surface of the carrier silicon, and [O] denotes a step of applying a photoresist to the entire surface of the carrier silicon.

[P] is a step of forming a mold for bending micro spring plating by forming a photoresist pattern by a photolithography process, and [Q] is an electroless plating of nickel or a nickel alloy.

Next, the process of forming the bumper is as follows. Reference numeral [R] denotes a step of applying photoresist to the entire surface of the carrier silicon on which the micro springs are formed, and [S] denotes a step of forming a bumper mold by forming a photoresist pattern by a photolithography process.

[T] is a step of manufacturing a bumper by electroplating nickel or a nickel alloy.

Next, the process of fabricating the probe head by bonding the manufactured bumper and the space transformer will be described. Reference numeral [U] denotes a step of aligning and contacting pads and bumpers formed on the space transformer, and [V] is a step of bonding the contacted portions by electroless plating.

Herein, in order to improve the bonding strength of the bonding process, preparing a recessed space transformer pad, inserting a bumper into contact with the pad of the recessed state transformer, and bonding the contacted portion by electroless plating It can be modified and applied to the step. In addition, the bonding strength may be further improved through diffusion bonding by heat treatment at a high temperature after the electroless plating bonding.

By the above process sequence, the probe tip, the bent micro spring and the bump formed silicon-on-insulated substrate are attached to the space transformer. Looking at the notation [W], the insulated substrate attached to the transformer is removed by wet etching to complete the probe head with the bumper, micro spring and probe tip sequentially attached to the transformer.

According to the present invention described above, it is possible to improve the thickness uniformity of the cylindrical probe tip, the bent micro spring, the cross section of the probe tip is similar to the cross section before wear.

By providing a joining method that allows precise alignment and joining of bumpers and space transformers attached to the other side of the microsprings, a more mechanically robust probe head can be produced.

As described above and described with reference to a preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as described above, it is a deviation from the scope of the technical idea It will be understood by those skilled in the art that many modifications and variations can be made to the invention without departing from the scope of the invention. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (7)

In the probe head, Cylinder shaped probe tips; A curved micro spring connected at one end to the probe tip; And A bumper formed at the other end of the microspring and bonded to a pad formed at the space transformer; Probe head comprising a. In the method for manufacturing a probe head consisting of a probe tip, a curved micro spring, a bumper, a space transformer, Forming through holes in the active silicon of the silicon on insulator substrate including the carrier silicon, the barrier oxide film, and the active silicon; Forming an inclined surface on the carrier silicon; Forming a probe tip in the through hole of the active silicon; Forming a bent micro spring connected at one end to the probe tip on the inclined carrier silicon; Forming a bumper at the other end of the microspring; Bonding pads formed on the bumper and the space transformer; And Removing the silicon on insulation substrate; Probe head manufacturing method comprising a. The method according to claim 2, Forming the probe tip, Forming a pattern of probe tips on the active silicon surface of the silicon on insulator substrate; Dry etching the probe tip pattern to form holes in the active silicon to form the probe tips up to the barrier oxide surface; Forming an inclined plane pattern on the carrier silicon; Wet etching the carrier silicon to the barrier oxide layer surface to form an inclined surface on which the bent micro spring is to be formed; Forming a silicon oxide film or a silicon nitride film on the inclined surface of the carrier silicon and the hole of the active silicon; Etching through the barrier oxide film near the top of the hole where the probe tip of the active silicon is to be formed to form a through hole in the silicon on insulation substrate; Bonding a seed substrate for electrolytic plating with a probe tip to a lower surface of the active silicon to utilize holes of the active silicon as a mold for electroplating; Electroplating a probe tip from the seed substrate; And Removing the seed substrate; Probe head manufacturing method characterized in that consisting of. The method according to claim 2, Bonding the seed substrate, Forming a metal seed pattern in the transparent glass substrate that matches the arrangement of the probe tips; Applying an ultraviolet adhesive to the glass substrate on which the metal pattern is formed; Positioning the glass substrate coated with the ultraviolet adhesive on the lower surface of the active silicon such that the metal seed pattern is positioned in the hole for forming the probe tip; Irradiating ultraviolet rays from the glass substrate to cure the ultraviolet adhesive to bond the glass substrate to active silicon; And Removing the ultraviolet rays on the metal seed pattern not irradiated with an organic solvent such as alcohol or acetone to form a seed layer for probe tip electroplating; Probe head manufacturing method characterized in that consisting of. The method according to claim 2, Forming the curved micro spring, Applying a metal layer to the front surface of the carrier silicon; Applying a photoresist to the entire surface of the carrier silicon; Forming a bent micro spring plating mold by forming a photoresist pattern by a photolithography process; And Electroless plating of nickel or nickel alloy; probe head manufacturing method comprising a. The method according to claim 2, Forming the bumper, Applying a photoresist to the entire surface of the carrier silicon on which the micro springs are formed; Forming a bumper mold by forming a photoresist pattern by a photolithography process; And Electroplating nickel or nickel alloy; Probe head manufacturing method comprising a. The method according to claim 2, Bonding the pad formed on the space transformer, Aligning and contacting pads and bumpers formed on the space transformer; And Bonding the contacted portions by electroless plating; Probe head manufacturing method characterized in that consisting of.

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