Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P70/00—Cleaning of wafers, substrates or parts of devices
  • H10P70/10—Cleaning before device manufacture, i.e. Begin-Of-Line process
  • H10P70/12—Cleaning before device manufacture, i.e. Begin-Of-Line process by dry cleaning only
  • H10P70/125—Cleaning before device manufacture, i.e. Begin-Of-Line process by dry cleaning only with gaseous HF
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
  • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
  • H10P50/282—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials
  • H10P50/283—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of inorganic materials by chemical means

Definitions

• the pressures of HF and carboxylic acid in the gas phase may vary between 1 Pa and 10 4 Pa.
• the specific partial pressures of respectively the HF vapour and the carboxylic acid vapour are 300 Pa and 600 Pa in etching techniques of Si0 2 and last step cleaning operations. Water can be added to enhance the etch rate or influence the selectivity of the etch rate for different types of oxides. When water vapour is present, the partial pressure of water may vary between 1 Pa and 10 4 Pa.
• FIG. 2 is a liquid/vapour phase diagram of HAc/H 2 0 mixtures.
• the process can be performed in the static mode and in the dynamic mode.
• Uniform etching is another important criterion that determines the usefulness of the process.
• the uniformity within the wafer and from wafer to wafer for a process using a batch of 6 wafers is represented in table 1.
• column 5 of said table 1 the standard deviation within the wafer is shown. As can be seen from these values, - the standard deviation within the wafer is not very good (32%) . Also there is quite a standard deviation from the wafer to wafer on the mean etch depth. In the presented case it is 27%. All these values show that the vapour HF/H 2 0 mixture does etch the Si0 2 but has not a good performance regarding reproducibility, within wafer uniformity and wafer to wafer uniformity. Detailed description of the preferred embodiments of the invention
• Anhydrous HF hardly etches silicon oxide at room temperature.
• a catalyst is necessary to start the reaction.
• H z O can fulfil this role, the adsorption of H 2 0 on the silicon oxide surface is dependent on the number of OH centres already present and in this way on the quality of the oxide.
• the adsorption of organic molecules shows a strongly reduced sensitivity for the amount of OH groups on the surface.
• the maximum density of adsorbed molecules strongly depends on the type of molecule. In table 2, the surface area occupied per adsorbed molecule is given for a number of different molecules. Obviously, acetic acid occupies the smallest surface area.
• the reaction involves the formation of SiF 4 and H 2 0 which are both gases at the used pressures :
• the etching of Si0 2 by HF generates water on the wafer surface.
• This water is, together with the acetic acid and the HF, assumed to be present in the form of a thin liquid film on the surface of the wafer and must be transported away from the wafer surface by evaporation.
• the acetic acid/H 2 0 phase diagram for liquid/vapour equilibria is determining.
• This phase diagram is shown in figure 2.
• the vapour and liquid curves are close together. This means that the composition of the vapour leaving the surface is close to the composition of the liquid on the surface.
• the shape of the curve implies that the vapour is even somewhat more water rich than the liquid. Consequently, the water generated on the surface can easily be transported away.
• the liquid and vapour curves are far apart resulting in a large difference between composition of the liquid and the vapour.
• the shape of the curves is such that the vapour is substantially less water rich than the liquid. Hence the water is not easily removed from the surface, giving rise to a strong increase in surface water concentration in the course of the etching process. This results in a fundamental controllability problem of the etching process which is not present with carboxylic acids and especially acetic acid.

Landscapes

• Drying Of Semiconductors (AREA)
• Cleaning Or Drying Semiconductors (AREA)
• Weting (AREA)
• Silicon Compounds (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8215342

Family Applications (1)

Country Status (7)

Cited By (291)

Families Citing this family (5)

Citations (5)

• 1994
  • 1994-05-10 WO PCT/EP1994/001534 patent/WO1994027315A1/en not_active Ceased
  • 1994-05-10 KR KR1019950704855A patent/KR100332402B1/ko not_active Expired - Fee Related
  • 1994-05-10 JP JP52497194A patent/JP3553939B2/ja not_active Expired - Fee Related
  • 1994-05-10 EP EP94916954A patent/EP0698282B1/en not_active Expired - Lifetime
  • 1994-05-10 AT AT94916954T patent/ATE196214T1/de not_active IP Right Cessation
  • 1994-05-10 DE DE69425821T patent/DE69425821T2/de not_active Expired - Lifetime
  • 1994-07-09 TW TW083104347A patent/TW253065B/zh not_active IP Right Cessation

Patent Citations (6)

Non-Patent Citations (1)

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